Study on the genesis of giant negative T wave in apical hypertrophic cardiomyopathy using a three-dimensional computer model.

Apical hypertrophic cardiomyopathy is characterized by a spade-like left ventricular cavity and by both giant negative T waves and tall R waves in the electrocardiogram. However, the mechanisms of these ECG abnormalities have not been satisfactorily clarified. We have recently developed a three-dimensional computer model of ventricular depolarization and repolarization processes. This model has successfully simulated normal QRST waves and changes characterizing some abnormal conditions. A model of apical hypertrophic cardiomyopathy was constructed by adding model units to the endocardium of the left ventricular apex. The surface ECG was then calculated by assuming different gradients of action potential durations and different proportions of the hypertrophic cells in the apical segment. A negative T wave of -1.45 mV in lead V4, similar to the clinically reported ECG, was obtained by assuming: (1) diffusely distributed hypertrophic cells at the apex and (2) uniform, long action potential durations of hypertrophic cells. It is suggested that these properties may account for the distinctive ECG abnormalities in apical hypertrophic cardiomyopathy.