Ecg of the month. Unusual electrocardiogram 42 years after operation for supravalvular aortic stenosis and 6 years after aortic valve replacement. Sinus rhythm with first degree atrioventricular block

A 43-year-old man came to the hospital because of increasing dyspnea for two weeks. At age nine months the patient was evaluated for failure to thrive, and a diagnosis of valvular aortic stenosis was made. At operation the aortic stenosis was found to be supravalvular, and the ascending aorta was enlarged with a Teflon patch, the proximal end of which was placed in the noncoronary sinus of Valsalva. The aortic valve was bicuspid but otherwise appeared normal. Postoperatively the patient did well until six years ago when he developed increasing dyspnea on exertion, orthopnea, and paroxysmal nocturnal dyspnea. Echocardiography revealed a peak systolic pressure gradient across the aortic valve of 80 mmHg, severe aortic regurgitation, and moderate mitral regurgitation thought to be functional. Coronary arteriograms were normal. The patient underwent aortic valve replacement with a 23 mm Hancock 2 porcine heterograft prosthesis. He again did well postoperatively until a year before the current admission when dyspnea on exertion developed and culminated in two weeks of severe orthopnea and paroxysmal nocturnal dyspnea. The electrocardiogram (ECG) recorded on admission is shown in the Figure.