Assessment of cardiac volumes and left ventricular mass by cine computed tomography before and after mitral balloon commissurotomy

We used cine computed tomography (CT) to determine whether decreased mitral valve gradients and pulmonary artery pressures resulted in decreased right ventricular and atrial volumes after percutaneous mitral balloon commissurotomy (MBC). In patients treated for severe mitral stenosis, previous studies have shown that after the mitral valve gradient decreases, the left atrial volume is reduced and left ventricular stroke volume is increased. The effects of commissurotomy on right heart chamber sizes have been difficult to assess with angiography and echocardiography. Moreover, in follow-up studies performed after surgery, changes in cardiac chamber volumes occurring after the mitral valve gradient and pulmonary pressure are reduced are confounded by the effects of thoracotomy. Our group has previously demonstrated that cine CT can accurately measure both left and right cardiac chamber volumes. We studied 11 female patients before, immediately after, and at 1 year after MBC, and 9 female control subjects of comparable age. To assess cardiac chamber volumes, we used cine CT. To assess the effects of MBC, we used cardiac catheterization and Doppler echocardiography. Compared to the control subjects, patients with mitral stenosis before MBC had larger total cardiac volumes (sum of all four chambers plus left ventricular myocardium) at ventricular end-diastole (381 ± 50 ml for controls vs 529 ± 102 ml for patients, p < 0.0005), larger left atrial (LA) end-diastolic volume and end-systolic volume (LA EDV: 72 ± 14 ml vs 186 ± 59 ml, p < 0.0005; LA ESV 31 ± 8 ml vs 143 ± 52 ml, p < 0.0005), and larger right atrial (RA) ESV (28 ± 6 vs 58 ± 23 ml; p < 0.005). RA EDV tended to be large (74 ± 18 ml vs 100 ± 31 ml; p < 0.10). Right ventricular (RV) EDV were similar (111 ± 23 ml vs 119 ± 23 ml; difference not significant). During cardiac catheterization immediately after MBC, the mitral valve gradient decreased (11 ± 3 mm Hg to 4 ± 1 mm Hg, p < 0.0001), mean pulmonary artery pressure decreased (29 ± 9 mm Hg to 20 ± 4 mm Hg; p < 0.025), and mitral valve area increased (1.1 ± 0.3 cm2 to 2.8 ± 1.2 cm2; p < 0.0005). These hemodynamic changes were confirmed by Doppler echocardiography. When cine CT studies obtained 5 ± 6 days after MBC were compared to studies obtained before MBC, LA ESV was found to decrease significantly to 119 ± 44 ml (p < 0.0005). RV EDV tended to increase (144 ± 24 ml) and was significantly larger than in controls (p < 0.025). At 1 year after MBC, the mitral valve area was unchanged from soon after MBC as measured by Doppler echocardiography (2.1 ± 0.5 cm2 vs 1.9 ± 0.5 cm2). Although the total cardiac volume was unchanged (552 ± 132 ml), significant changes in the individual cardiac chamber volumes occurred. Compared to before MBC, LA volumes decreased further (LA EDV was 158 ± 52 ml, p < 0.001; LA ESV was 102 ± 39 ml, p < 0.0005) and RV EDV increased further to 148 ± 46 ml (p = 0.057). The LV EDV tended to increase compared with before MBC and compared with control subjects (119 ± 34 ml; p < 0.10). The LV and RV end-systolic volumes and the RA end-systolic and end-diastolic volumes remained remarkably similar throughout. The LV mass increased (63 ± 11 vs 71 ± 12 gm/m2; p < 0.005). Thus in patients with mitral stenosis, the left and right atria are enlarged. After MBC, redistribution of cardiac chamber volumes occurs without a change in total cardiac volume.