Effects of balloon mitral valvuloplasty on left ventricular muscle function

Echocardiographically determined ventricular load and performance were compared in 40 consecutive patients with severe mitral stenosis before and 24 h after successful and uncomplicated balloon mitral valvuloplasty in order to clarify the role of loading conditions in causation of reduced left ventricular ejection fraction. After valvuloplasty, mitral valve area increased 2-fold. A modest increase in ejection fraction (53 ± 11% to 57 ± 8%, P = 0.021) occurred with an insignificant increase in end-diastolic volume (44 ± 10 to 48 ± 16 ml/m2, P = 0.063) and no change in wall stress (61 ± 19 to 59 ± 19 kdynes/cm3, P = 0.85) (105 DYNES = 1 N). There was no correlation between changes in fractional shortening and wall stress (r = 0.07) and between changes in end-diastolic volume and fractional shortening (r = 0.12). Contractile performance estimated by a performance-afterload relation was unchanged after the valvuloplasty. Factors other than a change in loading conditions might be responsible for a modest improvement in ejection performance following mitral valvuloplasty.