Changes in left ventricular performance during chronic pressure or volume overload: importance of physical properties of the arterial system.

The present study was aimed at evaluation of changes in systolic and diastolic left ventricular function during chronic pressure of volume overload, in comparison with normal subjects. Sixty-two patients were included: group 1 was composed of 25 normal subjects, group 2 was composed of 20 subjects with essential hypertension, and group 3 was composed of 17 subjects with aortic regurgitation without congestive heart failure. Cardiac output, aortic and left ventricular pressures (micromanometers), ventricular volume and ascending aortic radius (cineangiography), ejection fraction (EF), mean velocity of fiber shortening (VCF), ventricular mass (m), and the ratio m/EDV (EDV, end diastolic volume) were determined. Also measured were maxima for end systolic pressure (ESP), end systolic stress (ESS), and end systolic volume (ESV) and radius (ESR), as well as the modulus of left ventricular chamber and muscle stiffness (method of Gaash et al.) (1) and characteristic impedance of the ascending aorta (Zc). In hypertensive patients, m and m/EDV were increased, as was the ESP/ESV ratio, whereas EF and VCF were not modified and the ESS/ESR was normal or sometimes decreased. The systolic "pump" function thus appeared to be increased, whereas the muscle function appeared normal or decreased. The moduli of left ventricular chamber stiffness and muscle stiffness were increased. Zc was increased because of a greater pulse wave velocity, although aortic radius was larger. A close relationship was found between Zc and the ratio m/EDV. In patients with aortic regurgitation, the increased left ventricular mass was closely related to the regurgitant fraction (RF). The m/EDV ratio was normal. EF was unmodified and VCF and the ESP/ESV ratio were decreased.(ABSTRACT TRUNCATED AT 250 WORDS)