Differences in myocardial performance and load between patients with similar amounts of chronic aortic versus chronic mitral regurgitation

Abstract

It is not known if the favorable changes in preload and afterload that augment ejection performance in acute experimental aortic and mitral regurgitation are also present in patients with chronic regurgitation. Additionally, observations that patients with mitral versus aortic regurgitation respond differently to valve replacement suggest that differences exist preoperatively between these two types of volume overload. Therefore, ventricular mechanics were compared in nine patients with severe aortic regurgitation, eight patients with severe mitral regurgitation and seven normal subjects. The amount of volume overload was similar in both groups with regurgitation. In both aortic and mitral regurgitation, ejection performance was reduced compared with findings in normal subjects. Preload estimated as enddiastolic stress was comparably elevated above normal in both groups with regurgitation: 69 +/- 24 dynes X 10(3)/cm2 in mitral regurgitation compared with 81 +/- 34 dynes X 10(3)/cm2 in aortic regurgitation and 36 +/- 11 dynes X 10(3)/cm2 in normal subjects. However, afterload estimated as mean systolic stress was normal in mitral regurgitation (186 +/- 34 dynes X 10(3)/cm2) but markedly elevated in aortic regurgitation (260 +/- 41 dynes X 10(3)/cm2) (p less than 0.01). Contractile depression tended to be more severe in mitral regurgitation despite similar ejection performance in mitral and aortic regurgitation. Thus, in mitral regurgitation favorable loading conditions may mask contractile dysfunction, and in aortic regurgitation excessive afterload contributes to poor pump performance, possibly accounting for previously observed differences in the response to valve replacement.

Outcomes After Aortic Valve Replacement in Patients With Severe Aortic Regurgitation and Markedly Reduced Left Ventricular Function

“…A major reason for such a lower complication rate is that LV size and EF improve after AVR. This improvement is in stark contrast to the situation with mitral regurgitation, 20 in which EF usually decreases after surgery, even after valve repair. 21,22 Conversely, with a similar volume overload, EF generally improves after AVR for AR, probably because of afterload reduction measured as systolic wall stress.…”

“…21,22 Conversely, with a similar volume overload, EF generally improves after AVR for AR, probably because of afterload reduction measured as systolic wall stress. 20 Therefore, patients with a low EF and markedly increased wall stress are likely to benefit from decrease in wall stress with notable EF increase (5 percentage points on average) after surgery. 15 Improvement in EF is not uniformly distributed, 23 and patients with depressed EF before surgery improve the most after surgery.…”

Effects of aortic valve diseases on pressure profiles in selected locations of the human arterial system

“…[11][12][13]). The adequacy of the present computations can be partly verified with the measurement results from patients with AS and AR available in the literature [1][2][3][4][5][6][7][8][9].…”

“…In AR there is not only a volume overload but also an increase in the afterload and therefore of systolic wall stress. This distinguishes AR from mitral regurgitation [9], where a left ventricle volume overload is also present, but where the systolic wall stress is normal or even lower, since the regurgitant blood is ejected into the low pressure left atrium.…”

Does normal pump function belie muscle dysfunction in patients with chronic severe mitral regurgitation?

“…However, contractile function estimated as maxEN or EFc-end-systolic stress was frequently normal when the ejection fraction was preserved, which casts doubt on the concept that reduced afterload masks contractile dysfunction in chronic MR. Indeed, previous studies have also shown that afterload is normal or slightly increased in chronic MR,21 22 …”