Chapter 64: The Athlete and the Cardiovascular System
A 56-year-old woman presents for an exercise stress test. She completes 10.2 METS. The acute response to aerobic exercise includes increases in all of the following except:
A. Maximum oxygen consumption
D. Systolic blood pressure
E. Peripheral vascular resistance
The answer is E. (Hurst’s The Heart, 14th Edition, Chap. 64) The acute response to training for such athletic activities as cross-country skiing, long-distance running, swimming, or bicycling includes substantial increases in maximum oxygen consumption (option A), cardiac output (option B), stroke volume (option C), and systolic blood pressure (option D), associated with decreased (not increased) peripheral vascular resistance (option E).1 With several weeks of endurance training, the chronic adaptations to training include increased maximal oxygen uptake from augmented stroke volume and cardiac output and increased arteriovenous oxygen difference. The response to endurance exercise predominantly produces a volume load on the left ventricle.
A 29-year-old professional athlete is referred to you with left ventricle (LV) hypertrophy on his echocardiogram. Which criteria favor hypertrophic cardiomyopathy (HCM) or dilated cardiomyopathy over the athletic heart syndrome?
A. LV wall thickness ≥ 16 mm
B. LV hypertrophy with an unusual distribution (heterogeneous, asymmetric, or sparing the anterior septum)
C. Persistence of hypertrophy after physical deconditioning
D. LV end-diastolic diameter > 70 mm
The answer is E. (Hurst’s The Heart, 14th Edition, Chap. 64) Differentiating the physiologic changes resulting from habitual exercise in the athletic heart syndrome with HCM or dilated cardiomyopathy represents a challenge to the clinician. Physiologic cardiac adaptation from regular exercise leads to an increase in left ventricle (LV) wall thickness. This can be difficult to distinguish from the pathologic changes of HCM. Criteria favoring HCM include a high degree of LV hypertrophy (wall thickness ≥ 16 mm) (option A) with an unusual distribution (heterogeneous, asymmetric, or sparing the anterior septum) (option B), a small LV cavity (< 45 mm), the presence of striking electrocardiogram (ECG) abnormalities, and the persistence of hypertrophy after physical deconditioning (option C). Although many athletes have increased intracavitary dimensions, LV end-diastolic diameter > 70 mm is distinctly unusual as a manifestation of the athlete’s heart (option D). LV wall thickness > 12 mm is unusual even in highly trained athletes but is not uncommon in elite rowers and cyclists. LV wall thickness ≥ 16 mm raises the possibility of HCM. Hypertrophy (> 12 ...