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Excessive vasoconstriction in rheumatic mitral stenosis with modestly reduced ejection fraction
T Wisenbaugh1, R Essop, S Middlemost
1Baragwanath Hospital, Johannesburg, South Africa.
Journal of the American College of Cardiology
|November 15, 1992
Summary
In mitral stenosis patients, excessive vasoconstriction, not underfilling, likely causes reduced ejection performance and cardiac output. Contractile function remains normal despite severe inflow obstruction.
Area of Science:
- Cardiology
- Cardiovascular Physiology
Background:
- Mitral stenosis (MS) can impair left ventricular ejection performance.
- Underfilling due to inflow obstruction was hypothesized as a cause of depressed ejection performance in MS.
Purpose of the Study:
- To investigate factors differentiating ejection performance in mitral stenosis patients.
- To determine if underfilling explains depressed ejection performance in MS.
Main Methods:
- Compared ventricular load and performance in two groups of MS patients before and after balloon valvuloplasty.
- Group I: pre-valvuloplasty ejection fraction (EF) ≥ 0.55 (n=10).
- Group II: pre-valvuloplasty EF < 0.55 (n=11).
Main Results:
- Group II had smaller mitral valve area, higher end-systolic volume, lower cardiac output, higher systemic vascular resistance, and higher pulmonary vascular resistance.
- After valvuloplasty, mitral valve area increased significantly in both groups.
- Ejection fraction did not significantly increase post-valvuloplasty; contractile performance was within normal limits.
Conclusions:
- Excessive vasoconstriction may cause higher afterload, lower ejection performance, and reduced cardiac output in a subset of MS patients.
- Contractile dysfunction was not detected, and left ventricular filling was not subnormal.
- Modest improvement in filling post-valvuloplasty suggests vasoconstriction contributes to impaired hemodynamics.