A 67-year-old man with a history of hypertension and myocardial infarction 6 years ago presents to the ED with his wife.  He is not interested in coming to the ED, but his wife explains that he has been complaining of dizziness and fatigue over the past week.  On directed questioning, the man has no complaints of chest pain or palpitations.  He has baseline mild shortness of breath, but this does not appear to be much worse than usual.

His current medications include furosemide, lisinopril, and carvedilol; no allergies to report.  He denies past surgical history and his family and social histories are unremarkable.

You see a fatigued overweight man in no acute distress.

T 37.8     HR 60     110/60     RR 20     SpO2     98% RA

His examination is significant for a well healed incision in his left upper chest with a pulse generator pocket that is non-erythematous, non-edematous, and non-tender to palpation.  When you enquire about this, he explains that a pacemaker was placed when he had his heart attack.  The remainder of his physical examination is unremarkable, except for trace crackles at bilateral pulmonary bases.

His electrocardiogram follows:



Which of the following is the most likely explanation for his presentation:

    A.    Runaway pacemaker
    B.    Failure to capture
    C.    Pacemaker syndrome
    D.    Failure to sense


In the meantime, a quote –

“Diagnosis is a system of more or less accurate guessing, in which the endpoint achieved is a name.”  Lancet I: 619 (1944)

Thomas Lewis (1881-1945)

Physician and clinical scientist