Resident Survival Skills Arrhythmias

Bradyarrhythmias

Sick Sinus Syndrome Bradycardia/Tachycardia syndrome; Brady first Sxs: Syncope, palpitations, dizziness Diagnose with ECG or Holter. If inconclusive, need electrophysiologic testing If asymptomatic, leave alone. If symptomatic, needs pacemaker

First Degree AV Block Delay at the AV node results in prolonged PR interval PR interval>0.2 sec Discontinue PR prolonging drugs EP consult if symptomatic

Second Degree AV Block Type I (Wenckebach) Increasing delay at AV node until a p wave is not conducted Often comes s/p inferior MI with AV node ischemia Gradual prolongation of the PR interval before a skipped QRS. AV Node gets “fatigued” and fails to conduct impulse No tx if asymptomatic

Second Degree AV Block Type II (Mobitz) PR interval constant Sudden loss of a QRS wave because p wave was not transmitted beyond AV node. May be precursor to complete heart block and needs pacing PACE everyone

Third Degree AV Block Complete heart block where atria and ventricles beat independently AND atria beat faster than ventricles Must treat with pacemaker. Urgent EP consult

Pacemaker Indications 2nd degree AV block associated with signs ie. bradycardia, heart failure, and asystole greater than or equal to 3 seconds 2nd degree AV block with neuromuscular diseases ie. myotonic muscular dystrophy, Erb dystrophy, and peroneal muscular atrophy, even in asymptomatic patients (progression of the block is unpredictable in these patients) Mobitz II 2nd degree AV block with wide QRS complexes Asymptomatic Mobitz I 2nd degree AV block with the block at intra- or infra-His level found on EP testing (level II recommendation)

Tachyarrhythmias

AVNRT Most common cause of SVT, most common cause of palpitations in structurally normal hearts Paroxysmal, spontaneous or induced Regular rhythm, classic appearance = no P waves Responds to vagal maneuvers, adenosine

Atrial Flutter Flutter waves = “sawtooth pattern” Seen best II, III, aVF Conduction 2:1, 3:1, 4:1, variable (rarely 1:1) Regular rhythm, doesn’t cardiovert with vagal maneuvers/adenosine Variable conduction may mimic A fib

Atrial Fibrillation Most common sustained arrhythmia Irregularly irregular rhythm No P waves, fibrillatory waves may be present

Multifocal Atrial Tachycardia Rapid, irregular atrial rhythm from multiple ectopic foci within atria At least 3 different P wave morphologies (not PACs) Most commonly with severe COPD or CHF, poor prognostic sign Resolves with treatment of underlying disorder