Physiology Goes to the Hospital: Case 4

Sports fans everywhere were shocked and saddened by the death of Reggie Lewis, star player for the Boston Celtics basketball team. Mr. Lewis had collapsed on the court a few weeks before. One made the diagnosis of hypertrophic cardiomyopathy, and warned him about the hazards of aerobic exercise to his health. Mr. Lewis continued to train, and died suddenly while exercising. Autopsy confirmed the clinical diagnosis of hypertrophic cardiomyopathy.

You will see gross and microscopic pictures from a similar case in class.

What kind of things cause the cardiac output to drop precipitously but reversibly?

What is an "arrhythmia"? Why is this term ("a-" means "not") not really suitable?

Where is the outflow tract from the left ventricle into the aorta? What blocks it in hypertrophic cardiomyopathy?

What kind of murmur would be produced by a partial blockage to the outflow tract?

Why does cardiac output drop when the heart beats too fast? Too slow? Too unevenly? When the ventricle is not contracting and relaxing uniformly?

At what stage in the cardiac cycle do the coronary arteries fill?

What determines the length of systole?

What determines the length of diastole?

Cite Bernoulli's principle to explain why a rapid jet of blood through the left ventricular outflow tract interferes with filling of the coronary arteries.

How does depriving even a small portion of myocardium of adequate oxygen create the likelihood of rhythm disturbances?

How can ultrasonography assist with the diagnosis of hypertrophic cardiomyopathy?

Why is it important that people with hypertrophic cardiomyopathy limit their aerobic exercise?

How could you detect hypertrophic cardiomyopathy on a pre-sports physical exam?

For normal people, exercise is good for the heart. Explain why. Cite at least three reasons.

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