WEBVTT 00:00.125 --> 00:03.625 (loud continuous beeping) 01:29.488 --> 01:33.405 (whimsical instrumental music) 01:52.510 --> 01:53.946 - Hello, I'm Lieutenant Gee, 01:53.946 --> 01:55.550 and today we're going to continue our discussion 01:55.550 --> 01:58.507 of ectopic dysrhythmias. 01:58.507 --> 01:59.527 We're going to start today 01:59.527 --> 02:01.548 with the ventricular dysrhythmias. 02:01.548 --> 02:03.927 Previously, we've covered the sinus dysrhythmias, 02:03.927 --> 02:05.106 the atrial dysrhythmias, 02:05.106 --> 02:08.295 and the nodal, or junctional dysrhythmias. 02:08.295 --> 02:09.923 The ones we're going to cover now 02:09.923 --> 02:11.666 include the ventricular dysrhythmias 02:11.666 --> 02:14.103 and the atrial ventricular blocks. 02:15.707 --> 02:17.278 The ventricular dysrhythmias 02:17.278 --> 02:18.983 are among the most life-threatening 02:18.983 --> 02:20.660 of all the dysrhythmias. 02:20.660 --> 02:23.383 The focus of the ectopic pacemaker is the ventricle, 02:23.383 --> 02:25.301 which will inherently pace the heart 02:25.301 --> 02:28.082 at a rate of 30 to 40 beats per minute. 02:28.082 --> 02:30.304 However, with increased automaticity, 02:30.304 --> 02:33.020 rates may greatly exceed the inherent rate, 02:33.020 --> 02:35.440 and thus become life-threatening. 02:35.440 --> 02:36.562 This occurs because the ventricles 02:36.562 --> 02:37.580 cannot effectively empty, 02:37.580 --> 02:40.873 and thus cardiac output falls, or stops. 02:42.983 --> 02:44.450 First, we're going to talk 02:44.450 --> 02:47.080 about premature ventricular complexes, or PVCs. 02:47.080 --> 02:50.383 This slide you now see shows up PVC, 02:50.383 --> 02:52.920 shows an inherent sinus rhythm, 02:52.920 --> 02:54.063 or underlying sinus rhythm, 02:54.063 --> 02:57.327 with a premature ventricular contraction. 02:57.327 --> 03:01.113 In the diagram, you can see the ectopic focuses it fires. 03:07.002 --> 03:09.503 The impulse, as we've noticed, is the origin. 03:09.503 --> 03:11.767 The impulsive of origin is the ventricle, 03:11.767 --> 03:13.890 below the bundle branch blocks, 03:13.890 --> 03:15.290 and below the bundle of His. 03:16.702 --> 03:18.120 The origin of the PVC 03:18.120 --> 03:19.786 is outside the normal conduction system. 03:19.786 --> 03:22.280 Therefore, the conduction of the electrical impulse 03:22.280 --> 03:24.130 through the ventricles is abnormal. 03:24.130 --> 03:27.010 Depolarization arise from either ventricle, 03:27.010 --> 03:30.252 and the normal sequence of depolarization is altered. 03:30.252 --> 03:32.930 Instead of the two ventricles depolarizing, 03:32.930 --> 03:34.951 or contracting simultaneously, 03:34.951 --> 03:36.490 they contract sequentially. 03:36.490 --> 03:39.140 In addition, conduction occurs through the myocardium, 03:39.140 --> 03:43.303 rather than over specialized conduction pathways. 03:43.303 --> 03:44.812 This results in a wide 03:44.812 --> 03:47.887 and often bizarre appearing QRS complex. 03:47.887 --> 03:51.376 The sequence of repolarization is also altered, 03:51.376 --> 03:54.400 usually resulting in the ST Segment and T wave, 03:54.400 --> 03:56.610 being in the opposite direction 03:56.610 --> 03:59.104 to the normal QRS complex. 03:59.104 --> 04:02.781 There may be retrograde conduction to the atria, 04:02.781 --> 04:06.281 or there may not be retrograde conduction. 04:07.760 --> 04:09.770 If there is no retrograde conduction, 04:09.770 --> 04:12.720 a full compensatory pause is seen. 04:12.720 --> 04:14.462 Sinus rhythm is not interrupted. 04:14.462 --> 04:18.250 However, the P wave close to the PVC will not be conducted. 04:18.250 --> 04:21.408 The P waves will normally march through. 04:21.408 --> 04:23.570 With retrograde conduction, 04:23.570 --> 04:26.060 there is a partial compensatory pause 04:26.060 --> 04:28.393 and the SA node will reset itself. 04:30.161 --> 04:31.526 The EKG criteria, 04:31.526 --> 04:33.728 on the slide you see now, 04:33.728 --> 04:35.820 shows that the rhythm, 04:35.820 --> 04:39.521 usually causes the rhythm to look irregular. 04:39.521 --> 04:42.203 We need to look at the underlying rhythm, also. 04:43.500 --> 04:45.790 Rate depends on the underlying rhythm 04:45.790 --> 04:47.529 and the number of PVCs present 04:47.529 --> 04:49.133 and if they are profused or not. 04:50.292 --> 04:53.198 The ratio of Ps to QRS, 04:53.198 --> 04:54.390 usually there will, 04:54.390 --> 04:57.193 note P wave will be seen for the PVC. 04:57.193 --> 04:58.940 Occasionally however, 04:58.940 --> 05:02.110 retrograde conduction to the atria with a P prime, 05:02.110 --> 05:05.027 following the QRS, may be found. 05:05.027 --> 05:06.617 The configuration of the PVC 05:06.617 --> 05:09.396 is wide and bizarre appearing. 05:09.396 --> 05:10.953 The ST and T wave, 05:10.953 --> 05:13.460 often differ in polarity 05:13.460 --> 05:16.193 than the same components of normal complexes. 05:20.457 --> 05:22.874 Often, the T wave is notched, 05:23.855 --> 05:27.680 or often the QRS complexes may be notched, 05:27.680 --> 05:29.833 with a taller left rabbit ear. 05:29.833 --> 05:32.830 It is often followed by compensatory pause, 05:32.830 --> 05:36.120 the atrial rhythm of the underlying rhythm is undisturbed 05:36.120 --> 05:38.733 and P waves march through, out the PVC. 05:39.653 --> 05:42.095 There is no appreciable PR interval, 05:42.095 --> 05:44.360 as there are no P waves usually seen, 05:44.360 --> 05:46.792 and the QRS interval is prolonged. 05:46.792 --> 05:49.150 Greater than 0.12, 05:49.150 --> 05:49.983 but more frequently, 05:49.983 --> 05:51.940 with ventricular ectopy, 05:51.940 --> 05:53.390 is greater than 0.14 seconds. 05:58.332 --> 06:01.165 (papers rustling) 06:03.600 --> 06:06.148 This slide shows a Lead MCL One 06:06.148 --> 06:09.997 and shows inherent sinus rhythm with A PVC 06:10.852 --> 06:13.383 after the second normal complex. 06:14.570 --> 06:17.766 You see the polarity is different with the PVC 06:17.766 --> 06:20.023 than the inherent underlying rhythm. 06:21.252 --> 06:22.852 You notice the full compensatory pause, 06:22.852 --> 06:25.810 and if we were marching out these P waves, 06:25.810 --> 06:27.412 they would march completely through, out the strip. 06:27.412 --> 06:29.613 The sinus rhythm is undisturbed. 06:34.162 --> 06:36.999 In Lead Two, we see a sinus rhythm 06:36.999 --> 06:38.650 with two PVCs. 06:39.722 --> 06:43.710 This case, the polarity is the same as the normal complex. 06:43.710 --> 06:45.960 And if you look, you see retrograde conduction 06:45.960 --> 06:46.987 to the atria, 06:48.110 --> 06:49.670 with a small notched P wave, 06:49.670 --> 06:52.153 following that QRS complex. 06:53.538 --> 06:56.103 That P wave is riding on the T there. 07:02.091 --> 07:04.593 (papers rustling) 07:04.593 --> 07:06.594 Some of the significance or causes 07:06.594 --> 07:09.094 of ventricular ectopy or PVCs. 07:10.735 --> 07:12.274 There are a variety of causes 07:12.274 --> 07:14.993 that result from an irritable ventricle. 07:16.312 --> 07:18.533 Ischemia myocardial infarction, 07:18.533 --> 07:21.778 myocardial stretch related to CHF, 07:21.778 --> 07:24.314 significant anemia, hypoxia, 07:24.314 --> 07:27.148 caffeine, hypokalemia, 07:27.148 --> 07:31.122 or other electrolyte disturbances may initiate PVCs. 07:31.122 --> 07:33.770 They may be benign or considered dangerous 07:33.770 --> 07:35.370 and potentially life-threatening 07:35.370 --> 07:36.970 and require immediate treatment. 07:38.316 --> 07:41.030 When PVCs occur infrequently in a patient 07:41.030 --> 07:43.676 without other suspicion of heart disease, 07:43.676 --> 07:45.996 therapy may not be necessary. 07:45.996 --> 07:47.700 When therapy is indicated, 07:47.700 --> 07:49.500 it should be initiated promptly 07:49.500 --> 07:52.439 and Lidocaine is the drug of choice. 07:52.439 --> 07:54.350 A bolus of one milligram per kilogram 07:54.350 --> 07:55.799 of body weight should be given 07:55.799 --> 07:57.630 and followed by half a milligram 07:57.630 --> 07:59.280 per kilogram five minutes later. 07:59.280 --> 08:02.377 A continuous infusion should be started, 08:02.377 --> 08:06.696 one or two grams per 250 CCs of I.V. fluid, 08:06.696 --> 08:08.930 and it should be run at an infusion rate 08:08.930 --> 08:12.487 of one to four milligrams per minute. 08:12.487 --> 08:15.111 Lidocaine therapy should not exceed a loading dose 08:15.111 --> 08:16.855 of three milligrams per kilogram, 08:16.855 --> 08:19.605 as Lidocaine toxicity may result. 08:20.570 --> 08:23.015 Caution should be used in elderly patients. 08:23.015 --> 08:25.750 The signs and symptoms of Lidocaine toxicity 08:25.750 --> 08:28.096 include disorientation and confusion, 08:28.096 --> 08:29.810 drowsiness, lethargy, 08:29.810 --> 08:32.020 and other CNS symptoms. 08:32.020 --> 08:34.180 Finally, leading up to seizures. 08:34.180 --> 08:36.410 If the patient is refractory to Lidocaine, 08:36.410 --> 08:38.434 or allergic to other Caine drugs, 08:38.434 --> 08:41.874 a second line anti-dysrhythmic should we used. 08:41.874 --> 08:43.516 These may include Procainamide 08:43.516 --> 08:44.599 or Bretylium. 08:45.570 --> 08:49.415 There are a multitude of variations of PVCs. 08:49.415 --> 08:51.077 We're going to talk about a few of them, 08:51.077 --> 08:52.478 but this, by no means, 08:52.478 --> 08:54.143 exhausts the list of different kinds 08:54.143 --> 08:55.603 of PVCs you could see. 08:56.610 --> 09:01.340 This slide before you now, in Lead Two, 09:01.340 --> 09:02.944 shows unifocal PVCs, 09:02.944 --> 09:04.327 in which the ectopic focus 09:04.327 --> 09:07.122 is coming from the same spot in the ventricle. 09:07.122 --> 09:10.200 You notice that all the PVCs look the same. 09:10.200 --> 09:11.983 There are three in this strip. 09:15.004 --> 09:16.554 They have uniform (indistinct), 09:19.396 --> 09:23.950 whereas multi-formed PVCs appear different. 09:23.950 --> 09:26.773 There are more than one ectopic focus in this strip. 09:31.870 --> 09:34.611 This also shows the multi-formed PVCs 09:34.611 --> 09:37.583 coming from multiple foci in the ventricles. 09:42.334 --> 09:45.334 PVCs may occur in pairs or couplets. 09:46.371 --> 09:48.240 You notice the wide, bizarre QRS 09:48.240 --> 09:51.710 with the different ST segment and T wave polarity change 09:51.710 --> 09:52.890 in these. 09:52.890 --> 09:54.379 And you also notice the notching, 09:54.379 --> 09:55.560 or the rabbit ears, 09:55.560 --> 09:56.580 on the PVCs, 09:56.580 --> 09:58.663 with the left rabbit ear being taller. 10:03.560 --> 10:05.100 PVCs may occur in patterns, 10:05.100 --> 10:07.182 such as bigeminy or trigeminy. 10:07.182 --> 10:08.307 In a bigeminy pattern, 10:08.307 --> 10:11.630 PVCs come after every other beat, 10:11.630 --> 10:14.450 or every other beat is a PVC. 10:14.450 --> 10:15.846 They can also appear in couplets, 10:15.846 --> 10:20.690 where every two beats after a sinus beat is a PVC. 10:20.690 --> 10:24.483 And this is also called ventricular couplet bigeminy. 10:30.320 --> 10:33.506 They may fall on the T wave of a preceding QRS. 10:33.506 --> 10:36.110 Remember, in one of the inservices, 10:36.110 --> 10:38.210 we discussed what the vulnerable section 10:38.210 --> 10:41.246 of the T wave, where it was. 10:41.246 --> 10:44.180 And if a PVC, it falls on this vulnerable section 10:44.180 --> 10:45.210 of the T wave, 10:45.210 --> 10:49.363 you may initiate lethal ventricular arrhythmias. 10:51.189 --> 10:53.060 This strip is a little hard to see. 10:53.060 --> 10:54.920 I have a little bit better slide, 10:54.920 --> 10:56.053 a little bit later on. 11:00.383 --> 11:05.006 PVCs may be sandwiched in between the normal sinus beats. 11:05.006 --> 11:07.806 In this strip, we have a slow sinus bradycardia, 11:07.806 --> 11:09.187 and in between every, 11:09.187 --> 11:13.144 this is also a bigeminal pattern of sorts, 11:13.144 --> 11:15.833 but in between two sinus beats, 11:15.833 --> 11:17.613 there are sandwiched a PVC. 11:22.441 --> 11:25.450 And you would note, sinus rhythm is not interrupted 11:25.450 --> 11:26.310 on this strip. 11:26.310 --> 11:27.298 If you marched it out, 11:27.298 --> 11:28.917 the rhythm would remain the same, 11:28.917 --> 11:30.563 and it would not be interrupted. 11:33.351 --> 11:37.100 This slide shows at the top, 11:37.100 --> 11:38.710 paired PVCs, 11:38.710 --> 11:41.460 another variation of paired PVCs, 11:41.460 --> 11:44.680 and it shows another strip of R on T. 11:44.680 --> 11:46.610 You see the PVC falling on the T wave 11:46.610 --> 11:50.373 of that previous sinus beat very clearly. 11:51.406 --> 11:54.420 You also see on the third strip down, 11:54.420 --> 11:56.040 an end-diastolic PVC. 11:56.040 --> 11:58.791 This is actually a fusion type beat. 11:58.791 --> 12:00.050 You have the sinus rhythm, 12:00.050 --> 12:02.010 which is going along 12:02.010 --> 12:03.933 and where the sinus beat should be, 12:03.933 --> 12:05.510 you have a PVC. 12:05.510 --> 12:07.810 It's kind of a fusion between the sinus beat 12:07.810 --> 12:08.643 and the PVC 12:08.643 --> 12:11.170 but actually, the PVC initiated the beat 12:11.170 --> 12:13.330 at the same time and overrode 12:13.330 --> 12:14.893 the sinus node. 12:16.969 --> 12:19.570 Again, the sinus rate is not interrupted. 12:19.570 --> 12:21.237 And at the very end, 12:22.125 --> 12:24.037 is the interpolated PVC. 12:24.037 --> 12:27.651 The PVC is sandwiched in between two sinus beats. 12:27.651 --> 12:29.563 The sinus rhythm is uninterrupted. 12:37.100 --> 12:38.860 Three or more PVCs in a row, 12:38.860 --> 12:39.890 or a triplet, 12:39.890 --> 12:42.340 constitutes what we call ventricular tachycardia, 12:42.340 --> 12:44.371 which we'll discuss next. 12:44.371 --> 12:46.797 There are some variations to PVCs. 12:46.797 --> 12:50.513 We have ventricular fusion complexes. 12:50.513 --> 12:53.250 And this results when two impulses collide 12:53.250 --> 12:55.080 within the ventricles at the same time. 12:55.080 --> 12:58.040 These two impulses are of opposing electrical current, 12:58.040 --> 12:59.757 sinus and ventricular, 12:59.757 --> 13:02.615 fusing within the same chamber at the same time 13:02.615 --> 13:06.258 and the resulting ECG complex is often more narrow 13:06.258 --> 13:09.035 and of a lesser amplitude than the etopic beat alone 13:09.035 --> 13:09.868 would be. 13:15.935 --> 13:17.670 We've already discussed therapy. 13:17.670 --> 13:18.898 And this slide just reiterates, 13:18.898 --> 13:21.030 that within frequent PVCs, 13:21.030 --> 13:24.433 in patients with no other heart disease, 13:24.433 --> 13:27.454 frequently there is no therapy required 13:27.454 --> 13:30.120 but when PVCs become frequent, 13:30.120 --> 13:32.701 or patients become unstable with the PVCs, 13:32.701 --> 13:36.317 they need prompt treatment with IV Lidocaine or other drugs. 13:36.317 --> 13:38.077 Occasionally, if PVCs continue 13:38.077 --> 13:41.458 or initiate ventricular tachycardia, 13:41.458 --> 13:43.813 they require overdrive pacing. 13:49.090 --> 13:52.941 I want to talk just a moment about differentiating PVCs 13:52.941 --> 13:54.783 from ventricular aberrancy. 13:56.381 --> 13:59.130 Sometimes what appears on the surface 13:59.130 --> 14:00.660 to be ventricular in origin, 14:00.660 --> 14:03.560 may actually be aberrantly conducted. 14:03.560 --> 14:06.180 Aberrant means straying from the right way, 14:06.180 --> 14:07.470 or wandering. 14:07.470 --> 14:09.160 In ECG terminology, 14:09.160 --> 14:11.156 the term is used to indicate that although an impulse 14:11.156 --> 14:13.266 may have entered the ventricles in the normal way, 14:13.266 --> 14:15.882 through the AV node and bundle of His, 14:15.882 --> 14:18.913 its pathway within the ventricles is errant. 14:18.913 --> 14:23.140 This was discovered in 1970, when Marriott identified 14:23.140 --> 14:26.103 a method of recognizing aberrant ventricular conduction 14:26.103 --> 14:28.750 by QRS morphology. 14:28.750 --> 14:30.242 By using the MCL One Lead, 14:30.242 --> 14:33.500 a chest lead that simulates the V One Lead, 14:33.500 --> 14:36.927 he was able to deduce from the surface ECG, 14:36.927 --> 14:40.270 that the classic triphasic right (indistinct) branch pattern 14:40.270 --> 14:41.711 in V One and V Six, 14:41.711 --> 14:44.450 was helpful to him in distinguishing aberrancy 14:44.450 --> 14:46.170 from the ventricular ectopy. 14:46.170 --> 14:50.107 Some of the criteria determined that helped was, 14:53.071 --> 14:56.970 listed on this paper, which is a little difficult to read, 14:56.970 --> 15:00.490 but I'm not going to go into it any detail. 15:00.490 --> 15:01.850 Just some of the things that might help you 15:01.850 --> 15:05.071 is that a QRS greater than 0.14 15:05.071 --> 15:07.600 will favor ventricular ectopy, 15:07.600 --> 15:11.983 while a QRS of 0.12 would favor aberrancy. 15:14.020 --> 15:15.669 The presence of a compensatory pause, 15:15.669 --> 15:19.460 after the beat in question, 15:19.460 --> 15:21.105 would favor ventricular ectopy, 15:21.105 --> 15:23.850 while the absence of a compensatory pause, 15:23.850 --> 15:25.850 would favor aberrancy. 15:25.850 --> 15:28.271 And as we've noted in the NCL One Lead, 15:28.271 --> 15:31.669 a rabbit ear pattern with a tall left rabbit ear, 15:31.669 --> 15:34.287 favors ventricular ectopy, 15:34.287 --> 15:38.470 while a rabbit with a taller R rabbit ear, 15:38.470 --> 15:39.320 favors aberrancy. 15:40.870 --> 15:42.629 And also, if you're looking in V Four, 15:42.629 --> 15:46.417 a deep S wave would favor ventricular ectopy. 15:47.259 --> 15:49.958 In patients with a wide complex tachycardia 15:49.958 --> 15:51.816 resembling v-tach, 15:51.816 --> 15:52.693 remember to treat the patient 15:52.693 --> 15:55.610 and not necessarily the rhythm. 15:55.610 --> 15:57.420 A stable patient may or may not be in v-tach, 15:58.820 --> 16:02.083 or a super ventricular aberrant tachycardia. 16:03.050 --> 16:04.650 The key is to treat the patient 16:05.858 --> 16:08.143 until a better diagnosis can be made. 16:12.387 --> 16:13.720 This is an example 16:13.720 --> 16:15.720 of a premature atrial complex 16:15.720 --> 16:17.193 with a aberrant conduction. 16:18.363 --> 16:21.507 Again, this could fool you by think it is a PVC, 16:21.507 --> 16:25.763 because of the difference in polarity of the T wave there. 16:29.206 --> 16:33.373 But the QRS measurement on this one is about 0.12. 16:39.213 --> 16:41.760 This is a slide of atrial fibrillation 16:41.760 --> 16:43.763 with aberrant ventricular conduction. 16:45.968 --> 16:49.207 Again, you have the absence of the compensatory pause, 16:50.427 --> 16:54.211 you have a taller right rabbit ear than the left, 16:54.211 --> 16:56.763 even though that the polarity is different. 17:01.310 --> 17:03.753 We mentioned fusion beats a little bit ago. 17:03.753 --> 17:07.571 This is an example of a PVC followed by fusion beat. 17:07.571 --> 17:11.502 The PVC is the ectopic ventricle, 17:11.502 --> 17:14.190 focused in the ventricle firing. 17:14.190 --> 17:15.600 You have your compensatory pause 17:15.600 --> 17:17.971 and the sinus node was going to fire 17:17.971 --> 17:20.600 or did fire at the same time another PVC 17:20.600 --> 17:22.940 was initiated and they fused together. 17:22.940 --> 17:25.849 And what you see is a result in fusion beat, 17:25.849 --> 17:27.713 which has lower amplitude. 17:28.713 --> 17:30.187 And following that fusion beat, 17:30.187 --> 17:32.390 you see the sinus node kicked back in 17:32.390 --> 17:34.210 and you have a normal sinus beat. 17:39.556 --> 17:42.306 (paper rustling) 17:44.963 --> 17:49.144 We're going to talk briefly about ventricular escape. 17:49.144 --> 17:50.790 This slide shows the sinus node 17:50.790 --> 17:54.901 and the inherent sinus rhythm at the bottom of the screen. 17:54.901 --> 17:57.087 And you'll also see the ectopic focus 17:57.087 --> 17:59.584 below the bundle of His, 17:59.584 --> 18:01.405 firing the PVC. 18:01.405 --> 18:05.520 Again, the AV node did not receive a sinus beat 18:06.559 --> 18:09.790 within an appropriate amount of time. 18:09.790 --> 18:11.481 The AV node did not fire. 18:11.481 --> 18:14.201 So somewhere else down along the conduction pathway, 18:14.201 --> 18:16.660 decided to send off a signal 18:16.660 --> 18:18.370 and go ahead and fire and pace the heart. 18:18.370 --> 18:20.503 And this is what you see. 18:27.705 --> 18:30.262 Idioventricular rhythms, 18:30.262 --> 18:31.203 or IVR. 18:32.450 --> 18:34.770 This is a ventricular rhythm of the heart. 18:34.770 --> 18:35.841 Remember, the hear paces, 18:35.841 --> 18:39.042 the ventricle paces the heart 18:39.042 --> 18:41.625 at a rate of about 40 beats per minute. 18:41.625 --> 18:43.865 And if the sinus node does not initiate a beat, 18:43.865 --> 18:46.167 or the AV node initiate a beat, 18:46.167 --> 18:50.513 the ventricle will initiate a heart rate for the patient. 18:51.422 --> 18:54.985 And that's what you see here. 18:54.985 --> 18:57.620 You can tell that the complexes are ventricular in nature. 18:57.620 --> 19:00.920 Their QRS complexes are prolonged. 19:00.920 --> 19:01.753 They're wide and bizarre. 19:01.753 --> 19:03.433 There are no P waves. 19:04.401 --> 19:06.995 And this is different from a junctional rhythm. 19:06.995 --> 19:08.316 Number one, the rate's much slower 19:08.316 --> 19:12.050 than what the junction usually paces the heart at. 19:12.050 --> 19:14.163 Also, with a junctional rhythm, 19:14.163 --> 19:16.327 it's farther up the conduction system, 19:16.327 --> 19:19.193 and you will not see such a broad QRS complex. 19:25.190 --> 19:28.210 When the heart rate gets above 30 19:28.210 --> 19:30.910 but it definitely looks ventricular in origin. 19:30.910 --> 19:32.010 We may have what we call 19:32.010 --> 19:33.955 an accelerated idioventricular rhythm, 19:33.955 --> 19:35.250 or AIVR. 19:36.419 --> 19:38.520 This is greater than a heart rate of 30, 19:38.520 --> 19:40.830 which is the inherent heart rate of the ventricle, 19:40.830 --> 19:43.598 but less than a hundred beats per minute. 19:43.598 --> 19:46.477 If you have a ventricular rate greater 19:46.477 --> 19:47.640 than a hundred beats per minute, 19:47.640 --> 19:51.413 it would fall into the category of ventricular tachycardia. 19:52.254 --> 19:55.395 This is usually due to an area of altered automaticity 19:55.395 --> 19:56.873 in the ventricle. 20:00.371 --> 20:02.870 This dysrhythmia is often seen in the setting 20:02.870 --> 20:04.340 of myocardial infarction 20:04.340 --> 20:06.580 and is considered benign, 20:06.580 --> 20:09.660 unless it is the result of Dig toxicity. 20:09.660 --> 20:12.553 It frequently begins and ends with a fusion beat. 20:14.534 --> 20:17.695 You can see on this that the rhythm looks regular. 20:17.695 --> 20:20.700 The rate is about 40 to a 100 beats per minute. 20:20.700 --> 20:22.810 There are no P waves seen, 20:22.810 --> 20:24.877 so the ratio is zero to one. 20:26.037 --> 20:29.178 The configuration is a wide QRS complex 20:29.178 --> 20:32.012 from the ventricle focus, 20:32.012 --> 20:34.479 and the PR interval is not applicable, 20:34.479 --> 20:36.533 and the QRS interval is greater than 0.12, 20:37.375 --> 20:39.708 but usually great than 0.14. 20:43.876 --> 20:45.910 This slide just shows some of the things 20:45.910 --> 20:49.775 that can happen when we treat certain dysrhythmias. 20:49.775 --> 20:51.043 And we have to use a lot of caution. 20:51.043 --> 20:53.610 This is a idioventricular rhythm, 20:53.610 --> 20:54.770 the complex is wide, 20:54.770 --> 20:57.040 the underlying rhythm is an atrial fibrillation, 20:57.040 --> 20:58.735 or flutter and fib. 20:58.735 --> 21:01.880 You see a small period of sinus rhythm 21:04.382 --> 21:05.460 in the patient. 21:05.460 --> 21:07.012 And then he goes back into the AIVR, 21:07.012 --> 21:09.238 or the ventricular rate, 21:09.238 --> 21:11.665 and this patient wast treated with Lidocaine. 21:11.665 --> 21:14.832 It was mistaken for ventricular ectopy 21:17.370 --> 21:19.348 and treated with Lidocaine. 21:19.348 --> 21:22.450 And it abolished his ventricular rate completely. 21:22.450 --> 21:23.770 And this was the only rate that he had. 21:23.770 --> 21:27.910 This was the only mechanism providing him cardiac output. 21:27.910 --> 21:30.200 And all you see there at the bottom of the slide 21:30.200 --> 21:31.260 is flutter waves. 21:31.260 --> 21:34.260 And this patient went into cardiac standstill, 21:34.260 --> 21:39.123 or cardiac arrest because he had no ventricular pacing. 21:40.415 --> 21:41.720 So you must be careful 21:41.720 --> 21:43.720 on how you treat some of these patients. 21:47.514 --> 21:50.373 This is a PVC after a T wave, 21:50.373 --> 21:53.180 and it's not on the vulnerable part of the T, 21:53.180 --> 21:55.412 but it initiated a couplet there. 21:55.412 --> 21:57.694 You had a pause, you had one sign of speed, 21:57.694 --> 22:01.370 another PVC, which initiated a triplet, 22:01.370 --> 22:05.113 which forms a short run of ventricular tachycardia. 22:05.113 --> 22:07.983 Again, notice the tall left rabbit ear. 22:11.732 --> 22:14.565 (papers rustling) 22:17.732 --> 22:22.375 Ventricular tachycardia is an ectopic ventricular rhythm 22:22.375 --> 22:26.033 with a rate of a 100 to 200 beats per minute. 22:26.033 --> 22:28.540 As mentioned, it is present when there are three 22:28.540 --> 22:30.116 or more PVCs in a row, 22:30.116 --> 22:32.858 and it is extremely dangerous and life-threatening 22:32.858 --> 22:35.215 because the ventricular tach can be sustained 22:35.215 --> 22:39.519 or it can deteriorate quickly into ventricular fibrillation. 22:39.519 --> 22:44.250 In rare cases, the patient may be hemodynamically stable, 22:44.250 --> 22:45.234 but this is only temporary 22:45.234 --> 22:47.180 for if left untreated, 22:47.180 --> 22:48.673 the patient quickly deteriorates 22:48.673 --> 22:51.535 into a more lethal arrhythmia. 22:51.535 --> 22:54.583 BP falls due to inadequate cardiac output. 22:56.171 --> 22:58.676 Ventricular tachycardia may terminate spontaneously 22:58.676 --> 23:00.763 or with drug therapy. 23:02.015 --> 23:04.618 Although ventricular tachycardia can occasionally occur 23:04.618 --> 23:06.930 in healthy individuals, 23:06.930 --> 23:08.655 it nearly always is associated 23:08.655 --> 23:11.093 with advanced organic heart disease. 23:11.093 --> 23:15.156 The most common of which is coronary artery disease. 23:15.156 --> 23:17.420 The ischemia and myocardial necrosis 23:17.420 --> 23:19.890 which accompanies acute myocardial infarction, 23:19.890 --> 23:22.357 sets the stage for an irritable ventricle, 23:22.357 --> 23:24.913 and thus susceptibility for ventricular tach 23:24.913 --> 23:27.321 is greatly increased. 23:27.321 --> 23:30.660 Drugs may cause increased irritability of the ventricles, 23:30.660 --> 23:34.143 thus increasing its susceptibility and incidents, as well. 23:36.639 --> 23:39.819 It is a regular rhythm with a rate of one to 200 beats 23:39.819 --> 23:41.140 per minute, 23:41.140 --> 23:42.920 usually no P waves are seen 23:42.920 --> 23:46.431 but on rare occasions, can have retrograde conduction, 23:46.431 --> 23:49.877 and you may be able to see a P wave following the QRS. 23:50.852 --> 23:54.175 The QRS is wide and bizarre in configuration, 23:54.175 --> 23:57.350 looking much like that of the PVC. 23:57.350 --> 24:00.436 There is no PR interval measurable, 24:00.436 --> 24:02.600 and the QRS interval is greater than 0.12, 24:02.600 --> 24:05.353 and most often greater than 0.14. 24:10.575 --> 24:13.274 In treating the ventricular tachycardia, 24:13.274 --> 24:15.375 if the patient is hemodynamically stable, 24:15.375 --> 24:18.132 IV Lidocaine is the drug of choice. 24:18.132 --> 24:21.070 However, if the patient is (mumbling) to Lidocaine, 24:21.070 --> 24:22.890 other drugs such as Procainamide and Bretylium 24:22.890 --> 24:24.213 may be used. 24:25.270 --> 24:27.843 If the patient is hemodynamically unstable, 24:28.755 --> 24:32.554 DC countershock is the therapy of choice. 24:32.554 --> 24:35.730 If the patient is conscious, lower energy levels 24:35.730 --> 24:38.040 are used starting with 50 to a 100 joules, 24:38.040 --> 24:41.812 and increasing to two and 300 joules respectively. 24:41.812 --> 24:44.175 If the patient is unconscious and pulseless, 24:44.175 --> 24:46.687 the patient is treated as ventricular fibrillation 24:46.687 --> 24:49.930 and defibrillated with the sync mode off 24:49.930 --> 24:54.363 at two, three, and 360 joules respectively. 24:55.364 --> 25:00.225 Overdrive pacing may also be used if countershock fails. 25:00.225 --> 25:02.844 Remember, overdrive pacing is stimulating the ventricles 25:02.844 --> 25:06.028 to a rate over than what it is currently beating it, 25:06.028 --> 25:08.783 in order to break the reentry cycle. 25:12.437 --> 25:15.153 Regardless of what terminates the ventricular tachycardia, 25:15.153 --> 25:18.310 a continuous Lidocaine infusion should be started 25:18.310 --> 25:20.890 after the patient has been appropriately bolused. 25:22.423 --> 25:25.100 A precordial chest thump is only rarely successful 25:27.120 --> 25:29.810 and it's not recommended as a general rule. 25:29.810 --> 25:31.863 However, it is indicated if you observed the onset 25:31.863 --> 25:33.121 of V tach. 25:33.121 --> 25:35.250 To deliver a precordial thump, 25:35.250 --> 25:37.660 give the patient a thump to the mid-sternum 25:37.660 --> 25:39.430 with your clenched fist. 25:39.430 --> 25:41.520 This delivers about five millivolts 25:41.520 --> 25:42.580 of energy to the heart. 25:42.580 --> 25:45.140 And if administered early enough, 25:45.140 --> 25:47.240 maybe enough break a reentry circuit. 25:47.240 --> 25:49.427 But have a defibrillator on hand 25:49.427 --> 25:51.208 because this may also precipitate 25:51.208 --> 25:53.013 into ventricle fibrillation. 25:54.029 --> 25:56.820 A good way to remember where on the mid-sternum 25:56.820 --> 25:57.670 to deliver the thump 25:57.670 --> 26:00.851 is to place your elbow over the patient's umbilicus, 26:00.851 --> 26:04.060 and bring your clenched fist down on the sternum. 26:04.060 --> 26:06.248 The thump may be repeated times one 26:06.248 --> 26:08.131 and then cardioversion or defibrillation 26:08.131 --> 26:09.533 should be used. 26:13.011 --> 26:15.869 This is a classic example of ventricular tachycardia 26:15.869 --> 26:18.143 with a rate of 150. 26:19.109 --> 26:22.200 You see, there may be some retrograde (mumbling) 26:22.200 --> 26:23.033 on there, it's real hard to see, 26:23.033 --> 26:25.266 but this again, if you see this, 26:25.266 --> 26:27.088 you must look at the patient to determine 26:27.088 --> 26:29.425 how stable the patient is with this. 26:29.425 --> 26:31.830 I have seen patients up to four hours 26:31.830 --> 26:33.880 with sustained ventricular tachycardia, 26:33.880 --> 26:35.110 and they've had a good blood pressure 26:35.110 --> 26:37.560 and have been conscious and awake the whole time. 26:40.752 --> 26:42.015 The thing you must remember 26:42.015 --> 26:44.276 is that ventricular tachycardia, 26:44.276 --> 26:46.190 once it has been diagnosed, 26:46.190 --> 26:47.591 even in a stable patient, 26:47.591 --> 26:50.160 must be terminated at some point 26:50.160 --> 26:51.353 because a healthy heart 26:51.353 --> 26:55.950 will not even tolerate prolonged ventricular tachycardia. 26:55.950 --> 26:58.353 You will eventually begin to wear the patient down. 27:03.055 --> 27:06.149 This is a variation of ventricular tachycardia. 27:06.149 --> 27:09.012 This is generally not seen 27:09.012 --> 27:12.060 in a lot of places, it's rare. 27:12.060 --> 27:13.313 It's called torso de pointes 27:13.313 --> 27:14.831 but I have seen it several times 27:14.831 --> 27:17.300 since I've been in the coronary care unit here. 27:17.300 --> 27:19.070 And I think it's worthwhile to introduce you 27:19.070 --> 27:21.273 to this idea and what you may see. 27:22.353 --> 27:24.850 Torso de pointes is the French name 27:24.850 --> 27:26.428 meaning twisted points. 27:26.428 --> 27:29.160 It is given to the type of polymorphous 27:29.160 --> 27:32.437 but organized ventricular tachycardia. 27:32.437 --> 27:33.280 It may also 27:33.280 --> 27:36.753 be called bi-directional ventricular tachycardia. 27:36.753 --> 27:38.549 It is often paroxysmal 27:38.549 --> 27:41.211 and it often occurs in the setting of a long 27:41.211 --> 27:43.603 or prolonged QT interval. 27:44.871 --> 27:47.712 The long QT interval is often due to drug therapy 27:47.712 --> 27:50.610 with agents that increase the conduction time, 27:50.610 --> 27:54.775 such as Procainamide, Quinidine, or Lidocaine. 27:54.775 --> 27:56.275 And in some cases, (mumbling). 27:58.013 --> 28:00.471 It may also be the result of hyperkalemia, 28:00.471 --> 28:03.532 complete heart block, hypomagnesium, 28:03.532 --> 28:04.893 profound (mumbling), 28:04.893 --> 28:07.410 intercerebral pathology, 28:07.410 --> 28:09.393 psychotropic drugs, 28:09.393 --> 28:12.329 or low protein, liquid diets. 28:12.329 --> 28:14.453 High-protein liquid diets, rather. 28:17.370 --> 28:19.431 As you see, it is an irregular rhythm 28:19.431 --> 28:21.611 that is initiated by a PVC 28:21.611 --> 28:24.000 with a long coupling interval 28:24.000 --> 28:26.153 of 0.5 to 0.8 seconds. 28:26.153 --> 28:28.377 The rate is 150 to 250, 28:28.377 --> 28:31.483 occasionally reaching 300 beats per minute. 28:33.110 --> 28:36.857 Again, there's no P to QRS ratio applicable. 28:36.857 --> 28:40.217 The configuration is a wide bizarre QRS 28:40.217 --> 28:42.773 with the QRS polarity varying. 28:44.095 --> 28:47.420 It has a typical undulating spindle look. 28:47.420 --> 28:48.356 These undulations occur 28:48.356 --> 28:51.030 over runs and five to 20 beats. 28:51.030 --> 28:52.777 And the QT interval 28:52.777 --> 28:56.603 of the previous rhythm, the sinus rhythm, is long. 28:59.245 --> 29:02.676 The QRS interval of the (mumbling) complex 29:02.676 --> 29:06.313 is prolonged usually 0.14 seconds or greater. 29:08.777 --> 29:11.237 The onset of (mumbling) usually develops 29:12.890 --> 29:13.723 when (mumbling). 29:13.723 --> 29:14.620 And if you look closely 29:14.620 --> 29:17.370 at the beginning rhythm, the sinus rhythm, 29:17.370 --> 29:19.907 you see PQRS, a T, 29:19.907 --> 29:22.153 and you see actually looks like a notched T wave, 29:22.153 --> 29:25.170 that's a U wave riding on the end of that T. 29:25.170 --> 29:27.444 U waves develop in patients with normal rhythm, 29:27.444 --> 29:30.719 making the QT interval seem even longer 29:30.719 --> 29:33.705 and intermittent PVCs develop throughout the rhythm, 29:33.705 --> 29:37.721 occasionally developing into ventricular bigeminy. 29:37.721 --> 29:40.541 The PVCs develop longer coupling intervals 29:40.541 --> 29:44.600 and short runs as non-sustained V tach develop. 29:44.600 --> 29:45.807 This continues until a PVC 29:45.807 --> 29:48.487 will initiate the Torsades rhythm. 29:50.667 --> 29:54.230 Dysrhythmia is not responsive 29:54.230 --> 29:55.443 to conventional anti-dysrhythmic drugs used in V tach. 29:58.244 --> 30:00.363 Lidocaine frequently makes it worse. 30:02.890 --> 30:07.350 This does respond well to overdrive pacing 30:07.350 --> 30:08.300 or an Isuprel drip. 30:09.886 --> 30:12.823 Occasionally magnesium sulfate is also given. 30:14.505 --> 30:16.400 If Isuprel is used, 30:16.400 --> 30:17.233 you should mix a drip 30:17.233 --> 30:19.578 of one milligram and 250 CCs 30:19.578 --> 30:21.083 and hang the drop to run 30:22.720 --> 30:25.593 at in an infusion rate of two to 20 mikes per minute. 30:28.129 --> 30:31.351 Preventative care includes the measurement of QT intervals 30:31.351 --> 30:33.351 on admission to the CCU, 30:33.351 --> 30:36.130 and monitoring the measurements of QT intervals 30:36.130 --> 30:39.090 of all patients newly placed on anti-dysrhythmic, 30:39.090 --> 30:40.348 such as Quinidine, 30:40.348 --> 30:43.169 Procainamide, or Amiodarone. 30:43.169 --> 30:45.350 Notify the physician if the QT interval 30:45.350 --> 30:50.350 lengthens more than 33% beyond his normal, 30:50.664 --> 30:53.089 or beyond 0.5 seconds. 30:53.089 --> 30:55.570 Also monitor the QRS interval 30:55.570 --> 30:57.170 and notify the physician 30:57.170 --> 31:01.267 if it widens 25% or more of the patient's baseline. 31:09.013 --> 31:12.311 This slide just shows again some of the conditions 31:12.311 --> 31:16.322 in which Torsades de pointes is associated with. 31:16.322 --> 31:19.020 The drug related Quinidine, Procainamide, 31:19.020 --> 31:21.841 and other anti-dysrhythmics. 31:21.841 --> 31:23.820 The (mumbling) disrhythmias, 31:23.820 --> 31:24.784 SA node disease, 31:24.784 --> 31:27.706 there are some congenital syndromes, 31:27.706 --> 31:29.880 and other things, 31:29.880 --> 31:31.573 electrolyte disturbances. 31:35.701 --> 31:38.030 Again, this shows that ventricular tachycardia, 31:38.030 --> 31:41.585 may be with supraventricular tachycardia 31:41.585 --> 31:43.527 with aberrancy. 31:43.527 --> 31:45.280 And some of the things that favor V tach 31:45.280 --> 31:48.822 would be complete atrioventricular disassociation, 31:48.822 --> 31:50.960 not being able to march out, 31:50.960 --> 31:53.500 if there are Ps, being able to march the Ps out, 31:53.500 --> 31:55.690 independently of the ventricular, 31:55.690 --> 31:57.771 with both rate being regular. 31:57.771 --> 32:00.470 The QRS again, being greater than 0.14 second 32:00.470 --> 32:02.731 versus 0.12 second, 32:02.731 --> 32:05.243 and left axis deviation. 32:06.832 --> 32:10.308 (papers rustling) 32:10.308 --> 32:11.883 Ventricular fibrillation. 32:12.944 --> 32:15.690 This is in disorganized electrical activity 32:15.690 --> 32:17.190 that occurs in the ventricles. 32:18.128 --> 32:19.930 There is no cardiac output 32:19.930 --> 32:22.811 because there is no uniform contraction. 32:22.811 --> 32:24.331 In ventricular fibrillation, 32:24.331 --> 32:25.910 you have many ectopic foci 32:25.910 --> 32:29.425 trying to stimulate the heart to contract. 32:29.425 --> 32:32.420 As a result, no contraction results, 32:32.420 --> 32:35.535 and all you see is an undulating baseline 32:35.535 --> 32:38.293 or a chaotic disorganized baseline. 32:40.041 --> 32:43.881 There is no pulse because there is no cardiac output. 32:43.881 --> 32:46.220 This is the most single common cause 32:46.220 --> 32:48.540 of cardiac arrest resulting from myocardial ischemia 32:48.540 --> 32:50.738 or infarction. 32:50.738 --> 32:52.940 The quivering ventricles produce 32:54.837 --> 32:57.300 a chaotic erratic baseline 32:57.300 --> 32:58.895 on the ECG paper. 32:58.895 --> 33:01.340 The amplitude of this baseline may be coarse 33:01.340 --> 33:03.636 or it may be fine. 33:03.636 --> 33:07.043 The coarseness of the amplitude of V-Fib 33:08.800 --> 33:11.010 indicates a recent onset of the V-Fib, 33:11.010 --> 33:14.457 which can easily be corrected by prompt defibrillation. 33:14.457 --> 33:18.015 However, fine V-Fib usually reflects that it has occurred 33:18.015 --> 33:18.848 for some time 33:18.848 --> 33:21.480 and this form is generally more difficult to defibrillate 33:21.480 --> 33:25.003 without drug therapy to make it coarse. 33:33.750 --> 33:37.130 The rhythm, there is no distinguishable rhythm, 33:37.130 --> 33:39.855 all you see as an irregular chaotic baseline. 33:39.855 --> 33:42.793 There are no Ps to QRS that are seen. 33:44.834 --> 33:47.812 The rate is usually very rapid. 33:47.812 --> 33:49.033 The ventriculars are firing, 33:49.033 --> 33:54.033 ventricular rate is firing about 300 beats per minute, 33:54.195 --> 33:58.070 if it's trying to attempt to contract. 33:58.070 --> 34:00.434 There are no PR intervals and no QRS intervals 34:00.434 --> 34:02.184 that you can measure. 34:04.773 --> 34:07.778 The treatment and the significance of this, 34:07.778 --> 34:11.030 irreversible brain damage occurs after four minutes 34:11.030 --> 34:13.592 without cardiac output or oxygen. 34:13.592 --> 34:16.493 Since there is no cardiac output, there is no pulse. 34:16.493 --> 34:19.196 And if there has not been a respiratory reset 34:19.196 --> 34:21.380 when the cardiac arrest initiated, 34:21.380 --> 34:22.771 there will be one shortly 34:22.771 --> 34:27.771 in the fact that hypoxia will suppress the respirations. 34:28.607 --> 34:32.178 Basic life support needs to be initiated immediately. 34:32.178 --> 34:34.910 And immediate defibrillation is the definitive treatment 34:34.910 --> 34:39.474 with counter shocks of 200, 300 and 360 joules. 34:39.474 --> 34:41.516 If the defibrillation is unsuccessful, 34:41.516 --> 34:45.474 CPR is resumed and IV access obtained. 34:45.474 --> 34:49.774 Epinephrine is given to increase the vigor of the V-Fib 34:49.774 --> 34:53.394 and the dosage of that should be 0.5 to one milligram 34:53.394 --> 34:55.912 of a one to 10,000 solution. 34:55.912 --> 34:57.971 If you're unable to obtain IV access, 34:57.971 --> 34:59.815 the Epinephrine may be given via an ET tube 34:59.815 --> 35:02.014 if it's in place. 35:02.014 --> 35:05.537 Repeat the defibrillation after the Epinephrine 35:05.537 --> 35:08.935 is onboard and circulating via chest compressions. 35:08.935 --> 35:11.340 Lidocaine is also given IV push 35:11.340 --> 35:15.390 to help decrease the irritability of the ventricles. 35:15.390 --> 35:20.390 Again, repeat defibrillation is done with 360 joules. 35:21.079 --> 35:23.338 If defibrillation remains unsuccessful, 35:23.338 --> 35:25.457 a second anti-dysrhythmic maybe use along 35:25.457 --> 35:27.863 with repeated doses of Epinephrine. 35:28.894 --> 35:30.596 The Epinephrine should be repeated 35:30.596 --> 35:32.503 at five minute intervals. 35:33.492 --> 35:36.463 Other anti-dysrhythmics that may be used include Bretylium, 35:36.463 --> 35:41.463 Procainamide, are among the two most common. 35:44.212 --> 35:48.494 Ventricular fibrillation may deteriorate into asystole. 35:48.494 --> 35:50.882 Again, the use of the precordial thump 35:50.882 --> 35:53.087 may not prove to be effective but may be employed 35:53.087 --> 35:56.229 in the cases of witnessed arrest 35:56.229 --> 35:59.383 until the defibrillator is within reach. 36:04.111 --> 36:07.260 This is coarse ventricular fibrillation 36:07.260 --> 36:08.093 in Lead Two. 36:12.688 --> 36:16.145 This is fine ventricular fibrillation in Lead Two. 36:16.145 --> 36:18.770 Drug therapy, hopefully, can coarsen this up 36:18.770 --> 36:22.773 to make it more amenable to electrical energy on the chest. 36:27.293 --> 36:31.246 Ventricular standstill or ventricular asystole, 36:31.246 --> 36:32.931 this represents the total absence 36:32.931 --> 36:35.816 of ventricular electrical activity. 36:35.816 --> 36:38.952 Since depolarization or contraction does not occur, 36:38.952 --> 36:41.727 there is no cardiac output. 36:41.727 --> 36:43.930 This may occur as the primary event 36:43.930 --> 36:45.040 in a cardiac arrest, 36:45.040 --> 36:47.470 or it may follow ventricular tachycardia, 36:47.470 --> 36:49.229 or ventricular fibrillation. 36:49.229 --> 36:53.260 Occasionally, an agonal ventricular escape complex 36:53.260 --> 36:56.887 may be seen in the course of an agonal asystole. 37:01.685 --> 37:05.403 There is really no rhythm that is noted, 37:05.403 --> 37:08.065 no rate, and no ratio. 37:08.065 --> 37:09.565 The configuration is a flat 37:09.565 --> 37:10.770 or straight baseline 37:10.770 --> 37:14.290 with an occasional agonal ventricular escape complex. 37:14.290 --> 37:15.560 There is no PR interval 37:15.560 --> 37:18.242 and if there is an agonal escape complex, 37:18.242 --> 37:21.823 it will be greater than 0.14 seconds. 37:25.223 --> 37:27.986 Therapy includes basic cardiac life support 37:27.986 --> 37:30.546 initiated immediately and promptly, 37:30.546 --> 37:32.322 and continued maintained. 37:32.322 --> 37:37.139 Epinephrine, one to 10,000 is given IV push, 37:37.139 --> 37:39.881 in a dose of 0.5 to one milligram. 37:39.881 --> 37:42.386 Per the Iv or the ET tube. 37:42.386 --> 37:45.553 Atropine 0.5 to one milligram IV push 37:46.890 --> 37:49.303 is given to a dose of two milligrams. 37:50.418 --> 37:53.679 If the patient is acidotic by arterial blood gases, 37:53.679 --> 37:55.360 sodium bicarb is given 37:56.402 --> 37:58.296 and an external or transvenous, 37:58.296 --> 38:01.793 or transthoracic pacemaker may be used. 38:01.793 --> 38:04.561 An Isuprel drip may be hung at one milligram 38:04.561 --> 38:06.693 in 250 CCs, as well. 38:13.540 --> 38:17.623 This is ventricular asystole with an agonal complex. 38:20.542 --> 38:24.160 This rhythm has also been called the dying heart. 38:28.679 --> 38:31.512 (papers rustling) 38:33.442 --> 38:34.873 The final section of dysrhythmias 38:34.873 --> 38:37.370 is the one on atrial ventricular blocks 38:37.370 --> 38:40.035 and many people tell me, this is the most difficult 38:40.035 --> 38:42.510 to understand and diagnose. 38:42.510 --> 38:44.590 One key to understanding AV blocks 38:44.590 --> 38:46.810 is to first understand with each particular, 38:46.810 --> 38:49.328 where each particular block occurs. 38:49.328 --> 38:50.890 It can be in the node itself, 38:50.890 --> 38:52.566 in the bundle of His, 38:52.566 --> 38:56.032 or in one or more of the bundle branches. 38:56.032 --> 38:59.700 Remember, the farther down the electrical system you go, 38:59.700 --> 39:01.660 the slower the inherent heart rate will be, 39:01.660 --> 39:04.714 and the wider the QRS complex becomes. 39:04.714 --> 39:05.913 With these things in mind, 39:05.913 --> 39:09.203 we move onto the definition of AV block. 39:10.557 --> 39:13.008 Atrial ventricular block is defined 39:13.008 --> 39:16.223 as a delay or interruption in the conduction 39:16.223 --> 39:17.983 between the atria or ventricles. 39:18.906 --> 39:21.370 Most commonly, the block is located in the AV node, 39:21.370 --> 39:24.123 bundle of His, or the bundle branches. 39:25.168 --> 39:28.040 It may be due to an organic lesion 39:28.040 --> 39:30.550 along the conduction pathway, 39:30.550 --> 39:33.880 or an increases in the refractory period of some portion 39:33.880 --> 39:34.713 of the pathway. 39:36.850 --> 39:38.770 It is divided, AV block is divided in degrees, 39:38.770 --> 39:40.863 first, second, and third degree. 39:46.456 --> 39:48.000 And here's where you see the block 39:48.000 --> 39:49.523 is here or below. 39:55.170 --> 39:56.456 This is a little bit of a representation 39:56.456 --> 39:59.933 of the left ventricle with the AV node 39:59.933 --> 40:02.754 and bundle of His, and the bundle branches. 40:02.754 --> 40:05.074 It's a good picture in that it shows 40:05.074 --> 40:07.192 the complete right bundle branch 40:07.192 --> 40:10.625 as it goes down the right side of the septum, 40:10.625 --> 40:12.440 and the left bundle branch, 40:12.440 --> 40:15.382 which immediately bifurcates into two branches, 40:15.382 --> 40:17.821 the anterior and posterior vesicle, 40:17.821 --> 40:20.321 right after the bundle of His. 40:28.477 --> 40:32.140 Third degree AV block can occur at any level in the AV node, 40:32.140 --> 40:35.430 the bundle of His, or the bundle branches. 40:35.430 --> 40:38.023 It's the only block that can occur at any level. 40:39.279 --> 40:41.620 The first degree AV block occurs mainly 40:41.620 --> 40:43.380 in the AV node itself. 40:43.380 --> 40:45.580 And second degree AV block, 40:45.580 --> 40:47.540 which is further divided into two types, 40:47.540 --> 40:50.193 Mobitz Type One, or Wenckebach, 40:50.193 --> 40:51.993 and Mobitz Type Two. 40:53.511 --> 40:55.650 The type one, or Wenckebach, 40:55.650 --> 40:57.163 occurs in the AV node, 40:58.070 --> 41:01.103 while the type two block occurs in the bundle branches. 41:06.861 --> 41:09.683 We're gonna talk about the first degree AV block. 41:11.880 --> 41:13.650 This slide, let me back up just a moment. 41:13.650 --> 41:15.420 This slide just shows, again, 41:15.420 --> 41:17.997 where in the node and bundle branches 41:17.997 --> 41:19.352 that the different blocks occur. 41:19.352 --> 41:21.437 The AV node, first degree block, 41:21.437 --> 41:22.910 and second degree type one, 41:22.910 --> 41:23.743 as well as third degree, 41:23.743 --> 41:25.580 may occur in the AV node. 41:25.580 --> 41:26.413 In the bundle of His, 41:26.413 --> 41:28.680 third degree is the only block that can occur there. 41:28.680 --> 41:30.210 And in the bundle branches, 41:30.210 --> 41:32.137 you can have second degree type two, 41:32.137 --> 41:33.797 or the third degree. 41:38.756 --> 41:40.423 First degree AV block, 41:41.612 --> 41:43.650 this term is actually a misnomer 41:43.650 --> 41:45.152 because there really is a prolongation 41:45.152 --> 41:48.433 of conduction rather than a block of conduction. 41:48.433 --> 41:51.438 This delay in conduction is primarily at the AV node, 41:51.438 --> 41:55.054 and is a consistent delay in AV conduction. 41:55.054 --> 41:58.494 Impulses pass from the atria to the ventricles, 41:58.494 --> 42:00.958 but are delayed in a consistent fashion. 42:00.958 --> 42:03.998 All P waves are conducted and are all PR intervals 42:03.998 --> 42:05.107 are the same, 42:05.107 --> 42:07.840 but they are prolonged greater than 0.20 seconds. 42:09.622 --> 42:11.522 The rhythm will usually be regular, 42:11.522 --> 42:13.360 and the rate variable, 42:13.360 --> 42:14.687 with a one-to-one conduction. 42:14.687 --> 42:17.023 Configuration is usually normal. 42:17.023 --> 42:19.160 The PR interval, as noted, 42:19.160 --> 42:22.080 is greater than 0.20 seconds and constant. 42:22.080 --> 42:26.003 And the QRS interval is usually normal. 42:28.084 --> 42:31.790 First degree AV block occurs in approximately 13% 42:31.790 --> 42:33.770 of patients who develop acute MI, 42:33.770 --> 42:35.445 usually inferior wall. 42:35.445 --> 42:37.405 75% of these patients 42:37.405 --> 42:41.743 will go onto develop higher grade blocks. 42:46.562 --> 42:49.450 Other causes of AV block are Dig toxicity, 42:49.450 --> 42:50.928 ischemic heart disease, 42:50.928 --> 42:52.293 rheumatic fever, 42:52.293 --> 42:53.710 and hyperkalemia. 42:55.697 --> 42:58.530 (papers rustling) 43:01.546 --> 43:03.740 First degree AV block has also been seen 43:03.740 --> 43:06.370 in patients with no cardiac history. 43:06.370 --> 43:08.723 Specific treatment is not necessary but attention 43:08.723 --> 43:10.279 must be directed at the possibility 43:10.279 --> 43:14.218 of developing higher degree blocks. 43:14.218 --> 43:18.910 This shows representation of the prolonged PR interval. 43:18.910 --> 43:21.160 Normally, you're gonna have a PR interval of less 43:21.160 --> 43:23.473 than 0.20 seconds, or five small blocks. 43:27.741 --> 43:31.140 Second degree AV block is, as we've noted, 43:31.140 --> 43:32.280 divided into two types, 43:32.280 --> 43:33.556 type one and type two, 43:33.556 --> 43:35.000 or Mobitz One and Mobitz Two, 43:35.000 --> 43:37.850 after the man who first observed these patterns 43:37.850 --> 43:40.697 on the electrocardiogram in 1924. 43:40.697 --> 43:43.080 Both types of second degree block, 43:43.080 --> 43:45.861 some of the atrial impulses to the ventricles, 43:45.861 --> 43:48.190 thus conduction is blocked. 43:48.190 --> 43:51.523 Mobitz One, or Wenckebach, 43:51.523 --> 43:53.822 as it has been come to known. 43:53.822 --> 43:55.603 We're gonna talk about it first. 43:56.782 --> 44:01.782 Normally, the AV node has a slow response action potential 44:02.010 --> 44:03.545 and a slow conduction rate. 44:03.545 --> 44:05.570 Therefore, any depressive influence, 44:05.570 --> 44:08.790 such as digitalis or ischemia easily compounds 44:08.790 --> 44:09.865 the normal situation, 44:09.865 --> 44:12.307 causing the PR interval to lengthen, 44:12.307 --> 44:13.984 and the refractory period of that beat 44:13.984 --> 44:16.507 to extend into the next cycle. 44:16.507 --> 44:21.043 This beat causes closer and closer to the next P wave. 44:21.043 --> 44:23.203 As the PR intervals lengthen, 44:23.203 --> 44:25.940 the R to P intervals shorten 44:25.940 --> 44:28.670 until the P wave gets so close to the preceding R wave, 44:28.670 --> 44:30.910 that conduction is not possible, 44:30.910 --> 44:33.298 and a QRS complex is dropped. 44:33.298 --> 44:37.065 This has been called the Wenckebach phenomena, 44:37.065 --> 44:39.753 or a progressive PR lengthening. 44:41.219 --> 44:43.360 The EKG criteria, the rhythm 44:43.360 --> 44:44.900 will appear irregular ventricularly, 44:44.900 --> 44:47.918 but the atrial rate will appear regular, 44:47.918 --> 44:50.137 or rhythm will appear regular. 44:50.137 --> 44:52.579 By that, I mean the P waves will all march out 44:52.579 --> 44:54.155 in a regular fashion. 44:54.155 --> 44:55.303 The rate will be variable 44:55.303 --> 44:57.160 and the conduction is one-to-one 44:57.160 --> 44:59.223 until you reach the dropped QRS. 45:00.339 --> 45:01.721 Again, the configuration, 45:01.721 --> 45:04.140 you have a lengthening PR interval, 45:04.140 --> 45:05.982 until a QRS complex is dropped 45:05.982 --> 45:08.510 or not conducted to the ventricles. 45:08.510 --> 45:11.259 You will usually notice a grouped beating pattern. 45:11.259 --> 45:14.970 By this, I mean you will see groups of beats, 45:14.970 --> 45:18.568 starting with a normal PR, 45:18.568 --> 45:21.220 progressively longer PR, 45:21.220 --> 45:23.090 longer PR, then a drop beat. 45:23.090 --> 45:24.830 Having four complexes involved 45:24.830 --> 45:26.630 and this pattern will repeat itself. 45:30.446 --> 45:32.935 The QRS interval is usually unaffected, 45:32.935 --> 45:35.163 but if the QRS is prolonged, 45:35.163 --> 45:37.577 it's usually because there is both the AV block 45:37.577 --> 45:40.153 and some sort of bundle branch block, as well. 45:41.561 --> 45:43.487 The significance and treatment, 45:43.487 --> 45:45.210 treatment is usually unnecessary. 45:45.210 --> 45:47.757 With type one AV block, 45:47.757 --> 45:50.253 the block may be normal or abnormal. 45:50.253 --> 45:52.581 When it is abnormal, it is commonly associated 45:52.581 --> 45:54.420 with Dig toxicity, 45:54.420 --> 45:56.437 acute inferior wall MI, 45:56.437 --> 45:57.781 acute myocarditis, 45:57.781 --> 46:00.480 or the period following open heart surgery. 46:00.480 --> 46:01.781 And in these settings, 46:01.781 --> 46:03.207 it is usually transient 46:03.207 --> 46:04.719 and requires only observation. 46:04.719 --> 46:08.677 It is generally considered a benign dysrhythmia. 46:08.677 --> 46:11.630 Approximately, a half of the patients 46:11.630 --> 46:14.710 associated with acute inferior wall MI, 46:14.710 --> 46:17.979 will progress to higher grade or complete AV block. 46:17.979 --> 46:21.856 In patients with chronic type one AV block, 46:21.856 --> 46:23.333 it is considered benign 46:23.333 --> 46:25.717 unless they have organic heart disease. 46:25.717 --> 46:28.340 However, when there is organic heart disease, 46:28.340 --> 46:30.357 the prognosis is usually related to the severity 46:30.357 --> 46:32.190 of the disease itself. 46:33.595 --> 46:35.392 A hallmark, as I've mentioned of this, 46:35.392 --> 46:36.973 is group beating. 46:39.491 --> 46:41.413 This shows the Wenckebach phenomena 46:41.413 --> 46:43.950 with the normal PR interval, 46:43.950 --> 46:45.270 a little longer PR interval, 46:45.270 --> 46:46.213 longer still, 46:46.213 --> 46:47.440 longer still, 46:47.440 --> 46:50.220 until the P wave is conducted but not the QRS. 46:54.422 --> 46:56.837 Here again, you see the Wenckebach phenomena, 46:56.837 --> 47:00.620 type one with a progressive PR intervals. 47:00.620 --> 47:03.355 You can see by the dark lines on the ladder diagram, 47:03.355 --> 47:07.743 how long the PR interval is. 47:10.656 --> 47:13.113 This pattern here will repeat itself. 47:17.317 --> 47:21.510 This slide also shows Wenckebach phenomena. 47:21.510 --> 47:24.210 You see they've measured the PR intervals 47:24.210 --> 47:26.047 at the top slide for you and at the bottom slide, 47:26.047 --> 47:29.883 and you can see progressive PR interval lengthening 47:29.883 --> 47:31.220 until the dropped beat. 47:31.220 --> 47:34.900 And the top slide, you can see group beating very well. 47:34.900 --> 47:37.052 Three complexes and a dropped QRS, 47:37.052 --> 47:39.596 and in the next set, you see QRS complexes 47:39.596 --> 47:41.263 and the dropped QRS. 47:50.993 --> 47:52.291 In rare instances, 47:52.291 --> 47:56.033 there is two to one conduction in Wenckebach phenomena, 47:56.033 --> 47:59.596 in which group beating is usually not as apparent. 47:59.596 --> 48:00.796 In this rare instance, 48:00.796 --> 48:04.120 the PR interval will appear constant, 48:04.120 --> 48:07.203 but the QRS will appear normal in width. 48:08.252 --> 48:10.300 This is important to remember. 48:10.300 --> 48:13.970 We'll talk about PR intervals that remain constant 48:13.970 --> 48:18.970 with dropped beats and wide QRS complexes 48:19.610 --> 48:20.963 in type two block. 48:22.956 --> 48:25.920 Second degree type one block must be monitored 48:25.920 --> 48:27.840 for the progression of higher AV block. 48:27.840 --> 48:30.374 If the heart rate is excessively slow, 48:30.374 --> 48:32.614 Atropine may be given IV push, 48:32.614 --> 48:35.340 at 0.5 to one milligram, 48:35.340 --> 48:37.030 up to a dose of two milligrams 48:38.330 --> 48:39.240 to increase the heart rate, 48:39.240 --> 48:41.190 but only if the patient is symptomatic. 48:42.810 --> 48:45.391 (papers rustling) 48:45.391 --> 48:49.224 This slide shows second degree type one, also. 48:53.429 --> 48:55.290 You see the group beating quite well, 48:55.290 --> 48:56.780 the lengthening PR interval, 48:56.780 --> 48:58.808 and the dropped P riding on the very end 48:58.808 --> 49:00.113 of the T waves there. 49:07.000 --> 49:08.858 This is a representation of Wenckebach, 49:08.858 --> 49:10.973 but with a variable conduction rate. 49:12.175 --> 49:13.274 Instead of group beating, 49:13.274 --> 49:15.043 you see periods of group beating 49:15.043 --> 49:17.000 but in the third set over, 49:17.000 --> 49:21.990 you see only one QRS complex with a dropped QRS after that. 49:26.169 --> 49:29.666 Second degree type two, or Mobitz Type Two block, 49:29.666 --> 49:32.389 is usually within or below the bundle branches, 49:32.389 --> 49:34.760 below the bundle of His, 49:34.760 --> 49:36.230 and is almost always associated 49:36.230 --> 49:37.750 with right bundle branch block. 49:37.750 --> 49:39.690 And because of this complete block 49:39.690 --> 49:41.227 of one of the bundle branches, 49:41.227 --> 49:44.268 the QRS complex is usually broad, 49:44.268 --> 49:47.440 as apposed to, in type one, 49:47.440 --> 49:48.883 where the QRS is normal. 49:50.350 --> 49:53.788 In type two, some of impulses are conducted, 49:53.788 --> 49:55.800 while others are blocked. 49:55.800 --> 49:58.800 And you'll see P waves without QRS complexes. 49:58.800 --> 50:00.650 However, the hallmark of type two block 50:00.650 --> 50:02.873 is the PR interval remains constant. 50:05.176 --> 50:08.350 It is not unusual for more than one non-conducted beat 50:08.350 --> 50:10.078 to occur in a row. 50:10.078 --> 50:12.536 However, this is usually seen only when there 50:12.536 --> 50:15.173 is the complete block in one of the bundle branches. 50:18.977 --> 50:22.019 The EKG criteria, the atrial rhythm again, 50:22.019 --> 50:23.198 will be regular. 50:23.198 --> 50:24.753 The ventricular rhythm may be regular 50:24.753 --> 50:28.191 or may be irregular when varying conduction occurs. 50:28.191 --> 50:30.136 The atrial rate is unaffected, 50:30.136 --> 50:32.136 but the ventricular rate will be less 50:32.136 --> 50:33.886 than the atrial rate. 50:36.536 --> 50:39.953 The ratio may be constant or it may vary. 50:41.913 --> 50:44.755 The PR interval may be normal or prolonged at times 50:44.755 --> 50:46.233 but remains constant. 50:47.539 --> 50:50.099 And the QR interval, QRS interval, 50:50.099 --> 50:52.035 is rarely normal. 50:52.035 --> 50:53.603 It is usually wide. 51:01.415 --> 51:04.470 Type two is not as common as type one. 51:04.470 --> 51:08.238 It is associated with anterior septal wall MI, 51:08.238 --> 51:11.358 as opposed to inferior wall MI. 51:11.358 --> 51:12.739 And this is what causes the pathology 51:12.739 --> 51:15.140 in the bundle branch blocks. 51:15.140 --> 51:17.975 Type two block often progresses to complete heart block 51:17.975 --> 51:20.659 with a ventricular escape rhythm. 51:20.659 --> 51:22.630 Often, the patient is symptomatic 51:22.630 --> 51:25.635 with severe bradycardia and hypotension, 51:25.635 --> 51:27.140 or syncope. 51:27.140 --> 51:30.607 A permanent pacemaker is indicated when it is diagnosed. 51:30.607 --> 51:33.059 Because the block is below the node, 51:33.059 --> 51:35.180 it will not respond to Atropine, 51:35.180 --> 51:38.710 whereas type one, which occurs in the node, will. 51:38.710 --> 51:40.073 This is because Atropine acts to increase 51:40.073 --> 51:42.253 the automaticity of the sinus node, 51:42.253 --> 51:45.716 as well as improve conduction through the AV node. 51:45.716 --> 51:48.770 Isuprel may be used to increase the heart rate 51:48.770 --> 51:49.603 in this instance, 51:49.603 --> 51:50.979 to buy time until a temporary 51:50.979 --> 51:55.173 and eventually a permanent pacemaker can be placed. 51:56.177 --> 51:59.250 Isuprel is mixed as a drip. 51:59.250 --> 52:00.302 One milligram and 250 52:00.302 --> 52:03.660 and infused at a rate of 2 to 20 mikes per minute. 52:03.660 --> 52:05.500 And titrated to keep a heart rate 52:05.500 --> 52:07.433 of about 60 beats per minute. 52:08.995 --> 52:13.607 Again, this is used when the patient becomes symptomatic. 52:17.887 --> 52:22.579 This is a Lead Two strip showing a consistent PR interval 52:22.579 --> 52:25.450 with dropped QRS complexes 52:25.450 --> 52:28.718 and therefore, it's a type two block. 52:28.718 --> 52:32.398 I found one of the keys in looking at blocks, 52:32.398 --> 52:34.438 because it seems to confuse so many people, 52:34.438 --> 52:37.597 is to number one, you know it's a block 52:37.597 --> 52:39.976 if you see dropped QRS complexes, 52:39.976 --> 52:41.940 and then you just need to decide which block it is. 52:41.940 --> 52:44.320 You know it's not a first degree block 52:44.320 --> 52:47.491 because there are no dropped QRS complexes in first degree. 52:47.491 --> 52:50.034 So that leaves first, second, or third. 52:50.034 --> 52:55.034 One way to tell between the two types of second degree 52:56.330 --> 52:58.710 is you look for constant PR intervals. 52:58.710 --> 53:01.118 If your PR intervals are constant all the way through, 53:01.118 --> 53:03.543 this is a type two block. 53:06.700 --> 53:09.257 If your QRS, if your PR intervals vary, 53:09.257 --> 53:11.620 then you need to look for your group beating pattern, 53:11.620 --> 53:12.453 and if you find it, 53:12.453 --> 53:14.263 you probably have a type one block. 53:15.353 --> 53:18.435 This slide shows two representations 53:18.435 --> 53:20.697 of type two block. 53:20.697 --> 53:22.540 In the first and in the top portion, 53:22.540 --> 53:25.485 we see a type two block with a narrow QRS complex, 53:25.485 --> 53:27.820 and in the bottom, we see a type two block, 53:27.820 --> 53:31.940 Mobitz Type Two with a wider QRS complex. 53:31.940 --> 53:33.472 And this is because of where the block 53:33.472 --> 53:36.230 is developing in the node itself. 53:36.230 --> 53:40.910 Remember, I mentioned that type two occurs in, 53:40.910 --> 53:43.130 or type one occurs in the AV node alone, 53:43.130 --> 53:45.870 while type two occurs in the bundle branches. 53:45.870 --> 53:49.830 The top slide shows a little higher up the bundle branches, 53:49.830 --> 53:51.200 more probably towards the bundle of His, 53:51.200 --> 53:55.595 so you get more of a nodal, or narrow complex. 53:55.595 --> 53:58.397 The bottom slide is farther down the bundle branches, 53:58.397 --> 54:01.170 and the QRS complex is a little wider. 54:01.170 --> 54:02.912 Remember, as I told you, 54:02.912 --> 54:05.707 the farther down you go through the conduction system, 54:05.707 --> 54:07.670 the wider your QRS complex will get. 54:07.670 --> 54:10.870 And that's a key to watching for many 54:10.870 --> 54:12.277 of your disrhythmias. 54:18.610 --> 54:21.470 Third degree block is the last block 54:21.470 --> 54:22.950 that we're gonna talk about. 54:22.950 --> 54:24.891 This is complete heart block. 54:24.891 --> 54:28.620 It is diagnosed when no impulses can be conducted 54:28.620 --> 54:30.510 from the atria to the ventricles. 54:30.510 --> 54:33.150 It is characterized by a varying PR interval 54:33.150 --> 54:35.472 and non-conducted P waves. 54:35.472 --> 54:37.189 In other words, there is no relationship 54:37.189 --> 54:40.650 between the P waves to the QRS waves. 54:42.333 --> 54:45.643 The ventricular escape rhythm is usually idiojunctional, 54:45.643 --> 54:48.048 which means it's a narrow complex, 54:48.048 --> 54:50.430 because it's occurring at the level of the node, 54:50.430 --> 54:51.263 or bundle of His. 54:51.263 --> 54:55.110 But it may be also idioventricular, or wide, 54:55.110 --> 54:58.032 in which it's occurring at the level of the bundle branches. 54:58.032 --> 55:00.412 When it's idioventricular, or wider, 55:00.412 --> 55:02.410 it carries a less favorable prognosis. 55:02.410 --> 55:04.920 The ECG diagnosis 55:04.920 --> 55:07.480 of this dysrhythmia is usually straight forward. 55:07.480 --> 55:08.623 You can walk out the P waves 55:08.623 --> 55:11.300 and you can walk out the R waves independently 55:11.300 --> 55:13.859 to show two distinct rhythms. 55:13.859 --> 55:16.417 Third degree AV block, as we've noted, 55:16.417 --> 55:19.960 occurs both in the AV node and the bundle of His, 55:19.960 --> 55:21.443 or in the bundle branches. 55:23.656 --> 55:27.677 This slide shows the ectopic focus 55:27.677 --> 55:29.598 initiating the QRS complex, 55:29.598 --> 55:32.527 however the SA node is also initiating a complex 55:32.527 --> 55:34.755 but because of the block at the AV node, 55:34.755 --> 55:37.170 no atrial impulses reach the ventricle, 55:37.170 --> 55:39.367 so you have two independent pacemakers firing 55:39.367 --> 55:42.470 and you have two independent rhythms. 55:42.470 --> 55:45.290 P waves may be varied in the wide QRS complexes 55:45.290 --> 55:47.337 but if you take you calipers and march them out through, 55:47.337 --> 55:50.390 you will wind up marching those Ps all the way out 55:50.390 --> 55:51.240 across the strip. 55:54.595 --> 55:57.033 The EKG criteria shows the atrial rhythm regular 55:57.033 --> 55:59.560 and the ventricular rhythm is regular. 55:59.560 --> 56:02.697 The ventricular rate will be slower than the atrial rate, 56:02.697 --> 56:05.410 and when third degree AV block is at the level 56:05.410 --> 56:06.979 of the AV node and bundle of His, 56:06.979 --> 56:09.450 the rate is usually 40 to 60 beats per minute 56:09.450 --> 56:11.580 for the ventricle. 56:11.580 --> 56:13.155 And when it is below the node, 56:13.155 --> 56:15.256 the ventricular rate is usually less 56:15.256 --> 56:17.339 than 40 beats per minute. 56:18.659 --> 56:20.579 The P to QRS ratio is going to vary 56:20.579 --> 56:21.939 because there's no independent, 56:21.939 --> 56:25.373 there's no Ps directly related to QRSs. 56:26.419 --> 56:27.900 The configuration of the waves, 56:27.900 --> 56:30.410 of the P waves are normal, 56:30.410 --> 56:33.820 however, the QRS waves may be normal or broadened, 56:33.820 --> 56:36.173 depending on where it's occurring in the node. 56:37.968 --> 56:39.307 The significance or treatment, 56:39.307 --> 56:41.568 the patient will often by symptomatic 56:41.568 --> 56:45.328 with this block. 56:45.328 --> 56:48.140 Severe bradycardia accompanied by hypotension 56:48.140 --> 56:49.580 or syncope, 56:49.580 --> 56:52.144 they may or may not tolerate these symptoms. 56:52.144 --> 56:54.370 A permanent pacemaker is indicated 56:54.370 --> 56:56.304 when the block occurs below the node. 56:56.304 --> 56:57.427 If the patient is symptomatic, 56:57.427 --> 56:59.920 a temporary pacemaker may be placed 56:59.920 --> 57:02.063 until a permanent one can be inserted. 57:02.063 --> 57:06.540 Atropine may be given to improve heart rate 57:06.540 --> 57:08.300 and therefore, BP, 57:08.300 --> 57:11.010 if the block is at the node level. 57:11.010 --> 57:13.088 Remember, Atropine works only when the block 57:13.088 --> 57:15.460 is in the node. 57:15.460 --> 57:16.293 If it's below the node, however, 57:16.293 --> 57:18.637 Isuprel is the drug of choice. 57:20.557 --> 57:21.880 And the dosages of these drugs 57:21.880 --> 57:24.593 should be the same as what we've already discussed. 57:27.968 --> 57:30.694 This slide just represents a summary 57:30.694 --> 57:33.509 of the ECG features for all of the blocks 57:33.509 --> 57:37.050 and you can stop the tape at anytime if you want 57:37.050 --> 57:39.593 to look at the slide in detail. 57:45.060 --> 57:48.949 This is a development of third degree block 57:48.949 --> 57:51.350 with ventricular asystole. 57:51.350 --> 57:53.493 This is actually a faster ventricular rate 57:53.493 --> 57:54.820 than a lot of times you see, 57:54.820 --> 57:56.870 so that indicates that this is probably higher up 57:56.870 --> 57:57.703 in the node. 57:59.210 --> 58:02.340 The Ps and the QRS look like they go together 58:02.340 --> 58:04.469 but if you would really take time and look at this strip, 58:04.469 --> 58:06.650 I bet you would find that they are independent 58:06.650 --> 58:07.630 of each other. 58:07.630 --> 58:08.463 And all of a sudden, 58:08.463 --> 58:09.740 you have ventricular standstill 58:09.740 --> 58:11.890 and you have Ps that continue to march out. 58:15.254 --> 58:19.269 This is third degree AV block at the AV node level. 58:19.269 --> 58:21.947 And you see a narrower QRS complex 58:21.947 --> 58:25.408 and no real relationship between the Ps, 58:25.408 --> 58:27.930 no constant PR interval can be found there. 58:27.930 --> 58:29.467 You can't even find any group beating, 58:29.467 --> 58:32.267 so you know it's not a second degree type one. 58:32.267 --> 58:34.080 No constant PR interval, 58:34.080 --> 58:36.380 so it's not a second degree type two. 58:36.380 --> 58:37.830 So that leaves you with a third degree 58:37.830 --> 58:40.073 and then the last clue is your heart rate. 58:43.551 --> 58:45.517 This is a third degree AV block 58:45.517 --> 58:46.810 at the ventricular level, 58:46.810 --> 58:48.990 or down farther in the bundle branches. 58:48.990 --> 58:51.632 Again, you see the ventricular rate is slower, 58:51.632 --> 58:55.350 indicating it's farther down the conduction pathway 58:55.350 --> 58:58.380 and the QRSs are more broad, and wide, 58:58.380 --> 59:00.130 looking more ventricular in nature. 59:05.576 --> 59:08.482 This concludes our discussion of the major disrhythmias, 59:08.482 --> 59:10.642 and hopefully you feel more confident in your ability 59:10.642 --> 59:12.242 to interpret them. 59:12.242 --> 59:15.362 Remember, successful interpretation takes practice. 59:15.362 --> 59:16.807 The more strips you read, 59:16.807 --> 59:19.817 the easier the identification of these rhythms become. 59:19.817 --> 59:22.100 No doubt, you're going to run across something you 59:22.100 --> 59:23.485 will have trouble identifying. 59:23.485 --> 59:26.181 But don't worry, a myriad of complex 59:26.181 --> 59:28.823 and rare phenomena exist in the realm 59:28.823 --> 59:29.901 of electrocardiography. 59:29.901 --> 59:33.140 Try and reason it out using some of the guidelines 59:33.140 --> 59:33.973 I've given you, 59:33.973 --> 59:35.245 and if you still have difficulty, 59:35.245 --> 59:36.861 seek a resource. 59:36.861 --> 59:38.765 There are many texts that will assist you 59:38.765 --> 59:41.130 or ask your friendly cardiologist. 59:41.130 --> 59:43.976 The next area of discussion we'll focus on 59:43.976 --> 59:46.023 is the 12 Lead EKG. 59:46.023 --> 59:47.501 The normal appearance in each lead 59:47.501 --> 59:48.410 and how we may use the 12 Lead 59:50.260 --> 59:52.088 to help us identify a ischemia injury 59:52.088 --> 59:54.161 and infarction in patients at risk. 59:54.161 --> 59:56.308 We will not only be able to identify 59:56.308 --> 59:58.285 an evolving MI, 59:58.285 --> 01:00:00.482 but also where in the heart the damage is being done, 01:00:00.482 --> 01:00:03.142 and the coronary artery that is involved. 01:00:03.142 --> 01:00:04.802 Thank you. 01:00:04.802 --> 01:00:08.552 (upbeat instrumental music)