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 befor e and 24 h after successful and uncomplicated balloon mitral valvulopl asty in order to clarify the role of loading conditions in causation o f reduced left ventricular ejection fraction. After valvuloplasty, mit ral valve area increased 2-fold. A modest increase in ejection fractio n (53 +/- 11% to 57 +/- 8%, P = 0.021) occurred with an insignificant increase in end-diastolic volume (44 +/- 10 to 48 +/- 16 ml/m(2), P = 0.063) and no change in wall stress (61 +/- 19 to 59 +/- 19 kdynes/cm( 3), P = 0.85) (10(5) dynes = 1 N). There was no correlation between ch anges 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 ej ection performance following mitral valvuloplasty.