Sudden cardiac death in transposition of the great arteries with a Mustard or Senning baffle: the myocardial ischemia hypothesis.

PURPOSE OF REVIEW: The literature on sudden death in transposition of the great arteries (D-TGA) with atrial switch surgery is reviewed and a pathophysiological mechanism is proposed.

RECENT FINDINGS: Over 80% of sudden deaths in patients with D-TGA and Mustard or Senning baffles occur during exercise. Factors most consistently associated with ventricular arrhythmias and sudden death include heart failure parameters and atrial arrhythmias. Atrial arrhythmias have been observed to trigger malignant ventricular arrhythmias. Exercise may promote 1 : 1 conduction, with inordinately high ventricular rates. Reconstructed intra-atrial pathways are associated with an impaired stroke volume response to increased heart rates. A high prevalence of perfusion defects has been reported despite the absence of coronary atherosclerosis, particularly involving the inferior wall of the systemic right ventricle. Beta-blockers have been independently associated with a lower rate of ventricular arrhythmias in patients with implantable cardioverter-defibrillators.

SUMMARY: It is hypothesized that ischemia-related ventricular arrhythmias are a common mechanism for sudden death in patients with D-TGA and atrial baffles. Ischemia may be provoked by rapid heart rates from sinus or atrial arrhythmias. Myocardial oxygen supply/demand mismatch may be exacerbated by the impaired stroke volume response, hypertrophic remodeling of the pressure-loaded systemic right ventricle, and inefficient coronary circulation.