Correlation of age and heart weight with tortuosity and caliber of normal human coronary arteries

Abstract

Summary Whether or not the size of the epicardial coronary arteries can increase to keep pace with cardiac mass in abnormally enlarged hearts, and what the mathematical relationship is between the enlarging heart and its vascular tree, has been uncertain. Relationships were sought between patient's age, heart weight, coronary artery caliber, and tortuosity of epicardial coronary arteries in 145 cases with normal coronary arteries as judged by postmortem arteriography. The hearts were normal (33 cases) or had left ventricular hypertrophy (25 cases), right ventricular hypertrophy (30 cases), or myocardiopathy (57 cases) as a predominant pathological finding. Multivariable regression analysis for prediction of coronary artery caliber showed a direct linear relationship between heart weight and arterial diameter raised to the third power for normal hearts and those with left ventricular hypertrophy. Although coronary caliber was principally related to heart size, tortuosity which may be considered as length relative to distance traveled, also contributed to its prediction in the whole group. Tortuosity itself was predicted by an equation combining age positively and heart weight negatively to about equal importance and, to a lesser extent, arterial caliber positively. Tortuosity increases with age and with cardiac shrinkage; it increases in parallel with increase in coronary arterial caliber but decreases with cardiac enlargement. The results show that normal coronary arteries enlarge their caliber by at least the cube of the diameter proportionate to increase in heart size. It appears that this increase in caliber should be sufficient to maintain adequate blood flow to the myocardium and even very large hearts would not outstrip their blood supply.