[The relationships between left ventricular volumes and ejection fraction in mitral and aortic regurgitation (author's transl)]

Abstract

In 2 groups of patients with mitral valvular incompetence (MI, n equals 20) and aortic valvular incompetence (AI, n equals 22) intracardiac pressures as well as left ventricular volumes (enddiastolic volume, endsystolic volume, stroke volume, ejection fraction, regurgitant volume) were determined during routine left heart catheterization and left ventriculography. Data obtained were compared with a normal group (N, n equals 20). 1. Enddiastolic volume was increased by 32 per cent (MI) and 180 per cent (AI) respectively in comparison to normal. Endsystolic volume was increased by 85 per cent (MI) and 113 per cent (AI). Total stroke volume exhibited increases by 11 per cent (MI) and 86 per cent (AI) respectively. Regurgitant volume averaged 64 per cent (AI) of total stroke volume, and 47 per cent in MI. Left ventricular ejection fraction was reduced in both groups by about 12-14 per cent. 2. enddiastolic volume was significantly dependent on the amount of regurgitant volume in both groups (MI, AI). Likewise total stroke volume increased with increments in enddiastolic volume. This increase was far mor pronounced (up to 250 per cent of normal) in AI in comparison to MI and may be referred to an effective contribution of the Frank-Starling-Straub-mechanism, induced by increased preload following regurgitation. There existed no correlation between enddiastolic volume or regurgitant volume and the effective forward stroke volume and other parameters of forward pump function (effective cardiac output, cardiac index, external cardiac work). Left ventricular compliance, as determined by diastolic pressure-volume relationships, was nearly the same in the 3 groups (N, MI, AI). 3. Left ventricular ejection fraction was nearly unchanged with increments in enddiastolic volume over a range of enddiastolic volumes up to 400 ml. At higher enddiastolic volume (is greater than 400 ml) decreases were found. In the failing heart with AI left ventricular ejection fraction was reduced even at low enddiastolic volume, exerted by decreases of fibre shortening and contractility. In contrast, in MI ejection fraction decreased with increments of enddiastolic volume over the whole range investigated. The increase in total stroke volume in both groups therefore was produced by increases of enddiastolic volume and to a very small extent by an increase of the ejection fraction. 4. The large contractility reserve in compensated AI may be referred to the altered contraction mechanism in aortic valvular regurgitation associated with i) decrese of isovolumic pressure development and increase of isotonic contraction, ii) increase of diastolic fibre stretch (preload) and iii) decrease of mean wall tension. Contractility reserve was essentially influenced by myocardial contractility. With decreases of contractility consecutively decreases of the total and the effective pump function of the left ventricle may occur despite unchanged contraction form and left ventricular dimensions.