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Chapter 89: Pacemakers and Defibrillators

A 74-year-old man presents to the emergency department with shoulder pain. His past medical history is significant for a prior anterior wall myocardial infarction 3 years ago. Serial troponins are negative, and the shoulder pain is deemed to be musculosketal. An echocardiogram reveals an ejection fraction of 55%. However, his serial ECGs reveal sinus rhythm with alternating bundle branch blocks. His medications include aspirin 80 mg once daily and amlodipine 5 mg once daily. Which of the following statements is correct?

A. Proceed with dual-chamber pacemaker

B. Proceed with dual-chamber implantable cardioverter defibrillator (ICD)

C. Do not implant a device

D. Proceed with single-chamber pacemaker

E. Proceed with biventricular pacemaker

The answer is A. (Hurst’s The Heart, 14th Edition, Chap. 89) In contrast to indications for sinus node disease, pacing in acquired AV block is recommended even in asymptomatic patients if infranodal block (ie, intra-His or infra-His) is suspected. Patients with alternating bundle branch block (ie, right bundle branch block [RBBB] alternating with left bundle branch block [LBBB], or RBBB alternating with associated left anterior fascicular block and left posterior fascicular block), or with associated chronic bifascicular block and type 2 second-degree or advanced AV block, meet a class I indication for pacing, irrespective of symptoms. An implantable cardioverter defibrillator (option B) would not be indicated because of the normal cardiac function on echo. A single-chamber pacemaker (option D) would not be correct given the patient’s baseline sinus rhythm and the need for AV synchrony. Despite the likely scenario that this patient will be ventricular pacing most of the time, a biventricular pacemaker (option E) would not be indicated at this time given the normal cardiac function and the absence of New York Heart Association class II and greater.

A 70-year-old woman with remote implantation of a dual-chamber pacemaker for symptomatic sinus bradycardia is hospitalized for several days with an episode of new-onset atrial fibrillation. During her hospitalization, her pacemaker was reprogrammed to VVI 60 bpm. You are seeing her in follow-up and note that she is now back in sinus rhythm. Which of the following is a known effect of single-chamber (ventricular-only) pacing in the presence of sinus rhythm?

A. Increased incidence of ventricular tachycardia

B. Increased mortality

C. Improved quality of life

D. Increased incidence of pacemaker syndrome

E. Decreased incidence of atrial fibrillation

The answer is D. (Hurst’s The Heart, 14th Edition, ...

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