M.D.s and cardiologists, how did this heart defect kill my friend?

Now that I’m done the program for my friend’s funeral, the task has been given to me to give a brief explanation of his very sudden death.

Here’s what I know. He suffered from restrictive cardiomyopathy. The pathologist said it was a hereditary defect.

My first question is what sort of hereditary defect could have caused the stiffening of the heart muscles?

Secondly, the circumstances of his death matched those of sudden cardiac death from ventricular fribullation. I understand this, and my dad (an M.D. himself) said that it was probably a re-entry event that caused it. In other words, I know the most probable direct cause of his death.

Unfortunately, I don’t understand how the cardiomyopathy and the re-entry event connect. How could the stiffened heart muscles have disrupted the electrical signals in his heart?

Other important information: he was twenty-two, scrawny but middling-athletic (he biked and was on a campus rec soccer team), ate unhealthily, and led an unstressed life.

I’ve got nothing of use to add here, and I’m sorry for your loss.

Your user name’s rather apt for this occasion, though, I guess. Sorry.

It sounds like what you are talking about is IHSS, idiopathic hypertrophic sub-aortic stenosis, caused by a thickening, not stiffening of the intraventricular septum, the muscular wall between the right and left ventricles. This can result in sudden death, usually during exercise, as the thickened septum obstructs the outflow to the aorta. The first branches off the aorta are the three coronary arteries, so a lack of flow to the aorta causes a sudden loss of blood to the heart. The heart attack causes the fibrillation.