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☰ Essential ECGs for IBHRE
The Basic
Bradyarrhythmias
Show Answer 1st degree AV block. In a severe case (PR>330ms), symptoms similar to pacemaker syndrome may occur.
Show Answer Mobitz I or Wenckebach. Pacemaker is indicated if symptomatic.
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Show Answer Complete heart block. Escape rate is slow with RBBB and LPFB morphology.
Show Answer Intermittent complete heart block. 2Ps without any QRS. Underlying rhythm is sinus rhythm with RBBB and LAFB.
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Show Answer Bifascicular block with 1st degree AV block. Consider pacemaker if HV ≥70ms, evidence of infranodal block, or alternating BBB.
Show Answer Sinus pause
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Show Answer Sinoatrial exit block type II. Intermittent sinus pauses with the pause interval equals to the exact multiple of the preceding PP interval. In this case, the pause is 2x of PP.
Show Answer AF with conversion pause
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Tachyarrhythmias
Show Answer Atrial Fibrillation: irregularly irregular rhythm. Noted with fibrillatory waves in V1.
Show Answer Supraventricular tachycardia (SVT): Narrow complex tachycardia with no clearly visible P wave.
Show Answer Polymorphic VT with long QT or Torsade de Pointes.
Show Answer Idiopathic VT from RV outflow tract. Noted with positive QRS in II, III, and aVF; normal R wave progression in chest leads.
Show Answer Ischemic VT in a patient with history of inferior wall MI.
Show Answer Monomorphic VT. VA dissociation is clearly seen.
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Conditions with risk for sudden cardiac arrest
Show Answer Brugada ECG: J point elevation with coved-type ST elevation in V1-V2.
Show Answer Hypertrophic cardiomyopathy: high voltage in left-sided leads with ST depression and T wave inversion.
Show Answer Long QT
Show Answer Old MI; Noted with Q waves in inferior and anterior leads.
Show Answer Left: sinus rhythm with pre-excitation (delta wave; slurred QRS upstroke) = WPW EKG.
Right: AF with extremely fast conduction via accessory pathway or AF with WPW.
Jain et al. Circulation 2009.
Show Answer Arrhythmogenic right ventricular dysplasia (ARVD), a disease of right ventricule. Characteristic ECG findings include Epsilon wave (delay in depolarization) and T wave inversion in V1-V4.
Show Answer Early repolarization: J point elevation concaved downward ST elevation.
Show Answer Short QT
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Device related
1 week after implantation
Show Answer Dual chamber pacemaker with failure to sense and pace of V lead.
Given the timing of 1wk after implantation, lead dislodgement is most likely.
s/p VVI 10years+
Show Answer Single chamber pacemaker with failure to sense and pace of V lead.
Given the timing of 10years after implantation, lead fracture, insulation break, or battery depletion are possible. In this case, lead impedance was 1800 Ohm, so lead fracture was the cause.
DDD 60/120 AVD 170.
Show Answer A and V leads switch in the header. Ventricular pacing is being inhibited by P wave (middle tracing), ruling out lead dislodgement (there needs to be a lead in atrium). Inhibition of V pacing is intermittent due to higher sensitivity in A channel.
50F with complete heart block s/p DDD 8 years ago, presents with syncope. Pacemaker parameters are within normal ranges. Holter recording is as shown.
Show Answer Intermittent failure to pace the ventricle is noted. Oversensing is suspected.
Show Answer Normal pacemaker function. DDI 60, AVD 200.
VVI 50.
Show Answer Normal pacemaker function. Rhythm = sinus rhythm with AV Wenckebach. V pacing came on the dropped beats.
Show Answer Pacemaker mediated tachycardia; triggered by a PVC with retrograde P, followed by an non-capture A pacing with long AV delay, allowing the following retrograde VA conduction to capture the atrium and initiate PMT.
DDD 50/110, sensed AVD 120 ms, paced AVD 150 ms, PVARP 200ms
Show Answer Sinus tachycardia with pacemaker Wenckebach.
TARP = 200+120, UTR = 110 bpm = 546 ms, 2:1 block @ 320 ms or 188 bpm,
WKB 320-546 ms or 188 to 110 bpm.
DDD 70/110
Show Answer Safety pacing triggered by timely PVCs. Noted with short AV delays.
Show Answer Managed ventricular pacing: AAI mode switches to DDD with short AV delay after AP without native ventricular beat.
CRT non-responder. What is the next appropriate management? more info
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Show Answer Atrial flutter with intermittent biventricular pacing. Noted with beats of fusion and native LBBB.
65M s/p CRT, in ICU with pneumonia and respiratory failure. The device is programmed DDDR, 60-125 bpm. The most likely explanation for the below tracing is:
Show Answer Sinus tachycardia above upper rate limit; hence no biventricular pacing.
1hr after DDD implantation.
Show Answer The atrial lead has dislodged into the ventricle. Ventricular captures are seen by the first spike (from atrial lead) followed by a functional non-capture from the second spike (from ventricular lead).
1wk post CRT
Show Answer Normal CRT function with VV delay of 40ms.
VVIR; post chest radiation
Show Answer Pacemaker failure. Radiation may cause deterioration of lead and pacemaker circuit. ECG show asynchronous pacing. Urgent generator change is needed.
Show Answer Atrial undersensing. Some of A pacing spikes occur at the time of native QRS causing safety pacing.
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