Postoperative Electrocardiogram in a Man with the Marfan Syndrome

Abstract

A 53-year-old man with the Marfan syndrome had undergone aortic valve replacement with a Bjork-Shiley prosthesis for aortic regurgitation at another hospital 15 years earlier. At the same operation he had a Kay-type suture plication tricuspid annuloplasty of the posterior-septal commissure. He came to the cardiology clinic for preoperative clearance for inguinal hernia repair. An aortic regurgitation murmur was noted, and he admitted to exertional dyspnea. An electrocardiogram showed sinus rhythm, a normal P-R interval, and right bundle branch block. An echocardiogram revealed a dilated ascending aorta, severe aortic regurgitation due to a perivalvular leak, normal left ventricular systolic function, and pulmonary arterial hypertension with tricuspid regurgitation and a large right ventricle. Because of these findings he underwent a Cabrol procedure, i.e., a composite aortic valve and root replacement with reimplantation of the coronary arteries, and tricuspid valve replacement. Mechanical valves were used in both the aortic and tricuspid positions. A postoperative electrocardiogram showed sinus arrhythmia, at a rate of 88 beats/minute, that was completely dissociated from a regular, accelerated junctional rhythm, at a rate of 67 beats/minute, with right bundle branch block and left anterior fascicular block (Figure). Alternatively, the subsidiary pacemaker could have been in the left posterior fascicle. Many of the P waves were positioned where they would be expected to be conducted to the ventricles, but the perfectly regular ventricular rhythm indicated that none were. Thus, there was some degree of atrioventricular block. The relatively rapid subsidiary pacemaker may have contributed to the complete atrioventricular dissociation, and the atrioventricular block may have not been complete. Marriott has referred to this as “block-acceleration dissociation” (1). Figure Electrocardiogram recorded in the early postoperative period. See text for explication. Aortic valve replacement requires the surgeon to operate in close proximity to the atrioventricular conduction tissue (2). As a consequence, atrioventricular block and/or an accelerated junctional rhythm may develop, and the chances of this are greater if, as in this patient, the anatomy has been distorted by a prior operation. The rhythm disturbance in this patient is a combination of the two, i.e., a conduction disturbance in combination with increased automaticity. Other conditions, such as inferior myocardial infarction or digitalis toxicity, also may produce block-acceleration atrioventricular dissociation (1). Complete atrioventricular block is virtually never persistent in patients with inferior myocardial infarction or digitalis toxicity, and consequently these patients do not require permanent electronic pacing. In contrast, complete atrioventricular block developing after aortic valve surgery may be persistent, and those patients require permanent pacing (3, 4).