Workshop: Diagnosis of Cardiac Dysrhythmias

Transcription

1 Workshop: Diagnosis of Cardiac Dysrhythmias, FAAEM, FACEP 3/22/ :30 PM - 4:30 PM

2 Diagnosing Dysrhythmias, FAAEM, FACEP Associate Professor and Program Director Emergency Medicine Residency Baltimore, Maryland 1

3 I. Bradycardias and AV Blocks Sinus rhythm atrial and ventricular rate > 60 beats/minute P-waves upright in leads I, II, III, avf Sinus bradycardia sinus rhythm with atrial rate and ventricular rate 60 beats/minute Junctional escape rhythm Arises from AV junction, absent P-waves; ventricular rate beats/min. Ventricular escape rhythm Atrial activity usually absent; wide-complex rhythm with ventricular rate beats/min. First-degree AV block one P-wave for every QRS, prolonged PR interval > 0.2 sec Second-degreee AV block regular association between P waves and QRS complexes but occasional dropped QRS complexes Mobitz 1 (Wenckebach) progressive prolongation of the PR interval followed by a dropped QRS complex Mobitz 2 PR interval remains constant with intermittent dropped QRS complex Third-degree ( complete ) AV block dissociation between atrial activity (P waves) and ventricular activity (QRS complexes) PR interval varies randomly; P waves and QRS complexes map out independent of each other II. Tachycardias Diagnosis is based on Narrow or wide QRS complexes Regular or irregular QRS complexes Atrial activity Narrow regular Sinus tachycardia 1 P-wave for every QRS complex Supraventricular tachycardia P-waves may be hidden or may follow the QRS complex ( retrograde atrial activity ) Atrial flutter with 2:1 AV conduction 2 atrial beats for every QRS complex Must look carefully for atrial activity; is often obvious in only 1 or 2 leads Narrow irregular Atrial fibrillation no distinct regular atrial activity Atrial flutter with variable conduction regular atrial activity (F-waves) present Multifocal atrial tachycardia P-waves present, but irregular and with 3 different morphologies Wide regular Sinus tachycardia with bundle branch block or with WPW P-waves present Ventricular tachycardia(vt) P-waves often hidden, but occasionally seen (AV dissociation) Supraventricular tachycardia with bundle branch block P-waves often hidden Important points: No reliable way of ruling out VT on 12-lead ECG Always assume a regular wide complex tachycardia without distinct P-waves is VT and treat as VT! 2

4 Wide irregular Atrial fibrillation with bundle branch block No distinct regular atrial activity Ventricular rate rarely exceeds 200 beats/min QRS complexes have the identical morphology Atrial fibrillation with pre-excitation (e.g. Wolff-Parkinson-White syndrome) No distinct regular atrial activity Ventricular rate may approach 300 beats/min! At very rapid rates, appears regular (but it s not!) Often misdiagnosed as VT QRS complexes vary in morphology III. Other Dysrhythmias Polymorphic ventricular tachycardia Rapid regular wide QRS complexes QRS complex morphology varies in amplitude or shape When associated with prolonged QT intervals, is referred to as Torsades de Pointes Accelerated idioventricular rhythm (AIVR) Often referred to as slow ventricular tachycardia Ventricular rhythm with rate between beats/min. Often misdiagnosed as VT when rates are beats/min Often associated with reperfusion after acute myocardial infarction Ventricular fibrillation Extremely rapid disorganized ventricular activity By definition, no pulse is present, patient is unresponsive Immediate defibrillation is essential! IV. General Approach to Treatment Immediate treatment should be based on ventricular rate, not atrial rate! Bradycardias and AV Blocks Unstable patient (decreased level of consciousness, hypotension, acute ischemia, acute heart failure/pulmonary edema) Atropine Transcutaneous/transvenous pacing Dopamine infusion, epinephrine infusion Tachycardias Unstable patient Cardiovert (synchronized) if pulse is present Defibrillate (unsynchronized) if pulse is absent Stable patient Narrow QRS complex tachycardias Sinus tachycardia and multifocal atrial tachycardia search for and treat the underlying cause (e.g. hypoxia, ischemia, fever, etc.) Supraventricular tachycardia can try vagal maneuvers first Medications adenosine, calcium channel blockers, beta blockers 3

5 Atrial flutter and atrial fibrillation calcium channel blockers, beta blockers Wide QRS complex tachycardias Ventricular tachycardia lidocaine, amiodarone, procainamide Use of calcium channel blockers or beta blockers can be deadly! Supraventricular tachycardia with aberrant conduction Adenosine, calcium channel blockers, beta blockers will work However, unless you are absolutely certain this is an SVT, you should always assume VT and treat as with VT Amiodarone and procainamide are effective Atrial fibrillation with bundle branch block calcium channel blockers, beta blockers Atrial fibrillation with pre-excitation (e.g. Wolff-Parkinson-White syndrome) Beware all AV-nodal blocking agents, including adenosine, calcium channel blockers, beta blockers These may result in acceleration of ventricular rate and death! Amiodarone case reports of adverse outcomes Only effective treatments are procainamide or cardioversion Other dysrhythmias Polymorphic ventricular tachycardia If persistent, patient will quickly become unstable cardiovert or defibrillate If intermittent treat with magnesium (2-4 grams over minutes, then IV infusion) Always search or and treat underlying cause rapidly (e.g. electrolyte abnormality, medication causing prolonged QT interval, etc.) Accelerated idioventricular rhythm The rhythm itself requires no specific treatment Misdiagnosis as VT and treatment with antiarrhythmics may induce asystole Search for and treat any underlying cause (e.g. electrolyte abnormality, ischemia, etc.) Ventricular fibrillation Rapid defibrillation (200 joules, 300 joules, 360 joules) is the only proven effective treatment; Chances of successful resuscitation decrease significantly after the first three defibrillation attempts If delays with defibrillation, CPR should be performed If the first three attempts at defibrillation are unsuccessful, medications (epinephrine, lidocaine/amiodarone/procainamide) should be alternated with further defibrillations Following successful defibrillation, prophylactic medication (lidocaine, amiodarone, or procainamide) should be administered 4

6 CASES #1: 48 yo. man started new BP medicine, now c/o lightheadedness; SBP 80. #2: 57 yo. man who took too much of his BP medicine; SBP 80. 5

7 #3: 70 yo. woman with 4 days of nausea, vomiting, malaise; SBP 80. #4: 62 yo. man with SOB and chest pain; SBP 80. 6

8 #5: 85 yo. woman with syncope; SBP 120. #6: 48 yo. man with chest pain; SBP 80. 7

9 #7: 43 yo. man with syncope; SBP 60. #8: 65 yo. woman had a syncopal episode, now awake; SBP 78. 8

10 #9: 42 yo. woman with weakness; SBP 120. #10: 67 yo. woman with lightheadedness and nausea; SBP 70. 9

11 #11: 65 yo. man after syncope, now asymptomatic; SBP 120. #12: 39 yo. man with palpitations and lightheadedness; SBP

12 #13: 60 yo. woman with lightheadedness; SBP 140. #14: 65 yo. man with COPD exacerbation; SBP

13 #15: 45 yo. man with history of CAD; SBP 120. #16: 38 yo. woman with palpitations and lightheadedness; SBP

14 #17: 64 yo. man with nausea and vomiting; SBP 115. #18: 47 yo. man with chest pressure; SBP

15 #19: 22 yo. man with vomiting & diarrhea for 5 days, now with lightheadedness; SBP 75. #20: 75 yo. man c/o palpitations and chest pain; SBP

16 #21: 55 yo. woman presents with 24 hours of palpitations and lightheadedness; SBP 75. #22: 57 yo. man 1 hour after thrombolytics for AMI; SBP

17 #23: 45 yo. alcoholic with syncopal episodes; suddenly loses pulses. #24: 26 yo. man with palpitations and severe lightheadedness; SBP

18 Answer Key: 1. sinus rhythm with 1 st degree AV block, ventricular rate junctional rhythm, ventricular rate sinus tachycardia with 2 nd degree AV block type I (Mobitz I, Wenkebach), ventricular rate sinus tachycardia with 3 rd degree (complete) AV block, junctional escape rhythm, ventricular rate sinus rhythm with 2 nd degree AV block type II (Mobitz II) with 3:2 conduction, ventricular rate 50, LBBB 6. sinus rhythm with 2 nd degree AV block with 2:1 conduction, ventricular rate idioventricular rhythm, ventricular rate 38, hyperkalemia (postassium level 10.2) 8. sinus rhythm with 2 nd degree AV block type I (Mobitz I, Wenkebach), ventricular rate 52, RBBB 9. sinus bradycardia with blocked PACs, ventricular rate atrial flutter with variable AV conduction, ventricular rate 40, suggestive of digoxin toxicity 11. sinus tachycardia with 3 rd degree (complete) AV block with junctional escape rhythm, ventricular rate atrial flutter with 2:1 AV conduction, ventricular rate 140, was misdiagnosed as sinus tachycardia 13. atrial fibrillation with RBBB, ventricular rate multifocal atrial tachycardia, ventricular rate ventricular tachycardia, rate supraventricular tachycardia, ventricular rate sinus tachycardia with 2 nd degree AV block type I (Mobitz I, Wenkebach), ventricular rate 110, was misdiagnosed as atrial fibrillation 18. atrial flutter with variable AV conduction, ventricular rate sinus tachycardia, ventricular rate supraventricular tachycardia, ventricular rate atrial fibrillation, ventricular rate accelerated idioventricular rhythm (AIVR), ventricular rate Torsades de pointes 24. atrial fibrillation with Wolff-Parkinson-White syndrome Questions or comments? Please contact me: amalmattu@comcast.net 17