Junctional rhythm in hypertrophic cardiomyopathy: a case report.

We observed a case of a 47-year-old male patient with hypertrophic cardiomyopathy and family history of sudden death. During cardiac catheterization, the patient presented spontaneous intermittent atrioventricular junctional rhythm without significant changes related to sinus heart rate. The gradient was absent with sinus beats, but the junctional rhythm induced the appearance of a left ventricular-aorta gradient, with parallel reduction of aortic pressure from 156 to 120 mm Hg. Subsequently, a couple of pre-mature ventricular beats induced an important post-extrasystolic potentiation of the gradient, followed in the last beats by sinus rhythm with disappearance of the gradient. Our case suggests that the decrease of left ventricular volume, due to the absence of an effective atrial systole, leads to left ventricular increased gradient, not imputable to an increased inotropic effect or heart rate modifications but to the decrease of pre-load.