Variation of pressure with cycle length and duration of systole in the two-chambered cardiovascular model

Variation in the heart rate and the duration of systole modifies the pressures in the two-chambered model of the cardiovascular system by several mechanisms. The theoretical results indicate that prediction of chamber pressures would require moment-to-moment knowledge of the resistances peripheral to each chamber in addition to the cardiac output per cycle, cycle length, and duration of systole. Lengthening of systole with increase in cycle length—a physiologically observed relationship—theoretically stabilizes the end-diastolic pressure in the ascending aorta and may be a homeostatic mechanism to steady blood flow through the coronary arteries.