Left ventricular relaxation and diastolic stiffness in experimental myocardial infarction

Influence of right ventricular hemodynamics on left ventricular diastolic pressure-volume relations in man.

“…In view of the evidence that impairment of left ventricular relaxation may modify ventricular diastolic behavior under certain pathological conditions,3' 32 Brodie et al suggested that improved relaxation may contribute to the downward displacement of the diastolic pressure-volume function observed after administration of nitroprusside.' Direct relaxant effects of nitroprusside on cardiac muscle, relief of ischemia by favorably influencing the myocardial oxygen supply/demand ratio associated with pre-and afterload reduction, and endogenous catecholamine release were cited as mechanisms for such a change in relaxation.4…”

Factors which affect the diastolic pressure-volume curve.

“…The fact that (dp/dV)/p = k, the constant considered most important for quantifying the pressure-volume relationship in terms of the ventricle's passive elasticity, helped popularize this ratio as a way to describe diastole. 19 ' 22 ' 32 ' 33 This approach has been accepted widely despite the fact that Noble et al, 30 whose work is often cited to justify Equation 4, cautioned, "End-diastolic pressure often differed from that predicted by the exponential equation above, suggesting that it is not a reliable index of end-diastolic volume and left ventricular compliance. "…”

Factors contributing to altered left ventricular diastolic properties during angina pectoris.

“…Many factors influence the left ventricle in diastole, but the completeness of ventricular relaxation and external diastolic constraints of the ventricle are among the most important.5' [12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30] With regard to external constraints, attention has focused on the influence of the pericardium, right ventricular loading, and coronary perfusion pressure" [18][19][20][21][22][23][24][25]30 on left ventricular diastolic compliance. Glantz and Parmley have suggested that during ischemia induced by atrial pacing, increased rightsided volume and pressure cause the left ventricular diastolic pressure-volume curve to shift upward as a result of "direct mechanical coupling between the two ventricles," enhanced by the intact pericardium.5 They cite data of Weiss et al 26 as being inconsistent with the concept that impaired relaxation is playing a major role in causing the altered left ventricular diastolic pressures, as had been suggested by several investigators.4 ' 6, 12, 13, 15, 16 The present study was designed to examine the role of altered right ventricular loading and pericardial influences on the increased left ventricular diastolic pressure during angina.…”