Epicardial activation of the human ventricle: Effects of left ventricular hypertrophy

To determine the effects of left ventricular hypertrophy on eplcardlal activation of the human heart, Intraoperative eplcardlal mapping of 40 to 66 points was performed In 10 patients undergoing aortic valve replacement. Mean calculated left ventricular mass was 364 ± 98 g. All patients had normal left ventricular contraction. Earliest eplcardlal activation occurred In the anterior right ventricle In all patients. In 9 patients, it was the only eplcardlal breakthrough point. One patient had a single Inferior left ventricular breakthrough point. Eplcardlal activation spread from the right ventricle towards the left ventricle in both the anterior and inferior direction. Latest eplcardlal activation occurred at the base of the left ventricle In 9 patients and the base of the right ventricle In 1.When compared with patients with coronary artery disease, normal ventricular contraction, and no left ventricular hypertrophy, patients with hypertrophy had fewer left ventricular breakthrough points (p <0.001) and were more likely to have latest activation at the left ventricular base (p <0.001).We conclude that left ventricular hypertrophy Is associated with marked changes In the pattern of epicardlal activation. These changes may reflect delay In spread from endocardium due to the increased wall thickness.