ACUTE CHANGES IN LEFT-VENTRICULAR FUNCTION AFTER PERCUTANEOUS TRANSLUMINAL MITRAL VALVULOPLASTY

Percutaneous balloon mitral valvuloplasty (PBMV) has been shown to ind uce an immediate increase in the left ventricular end-diastolic volume , which increase, in turn, has been attributed to an increase in left ventricular compliance. We studied 51 patients, 41 women and 10 men, w ho underwent PBMV, and were in sinus rhythm before and after the proce dure. Heart rate did not vary significantly. There were increases in l eft ventricular end-diastolic volume (97.5 +/- 25.6 vs 112.7 +/- 25.7 ml/m(2), P < 0.001), left ventricular end-diastolic pressure (8.7 +/- 3.0 vs 9.7 +/- 4.3 mmHg, P = 0.04), and both left ventricular systolic pressure and stress (118 +/- 20.5 vs 123 +/- 23.2 mmHg and 468 +/- 12 9 vs 580 +/- 164 mmHg; P = 0.04 and P < 0.001), respectively). The ela stic stiffness constant did not vary (16.2 +/- 1.9 vs 15.7 +/- 1.9 (di mensionless units), P = 0.2). The increase in volume seemed to be part icularly important when the ventricle appeared to be ''shrunken'' befo re PBMV. This increase was still present after a 1 year follow up. Thu s, PBMV determines an increase in both end-diastolic volume and pressu re, so that the left ventricle appears to move along a single pressure -volume curve. This enlargement evokes the Frank Starling mechanism, a nd improves systolic performance. Since it is still evident after a 1 year follow up, some concern may arise when a simultaneous volume over load is present, as in aortic insufficiency.