[Radionuclide assessment of left ventricular diastolic function in patients with mitral stenosis before and after percutaneous transvenous mitral commissurotomy; use of list mode method in patients with atrial fibrillation]

To evaluate the effect of percutaneous transvenous mitral commissurotomy (PTMC), equilibrium radionuclide angiocardiography was performed in eight patients with mitral stenosis who had atrial fibrillation. Accurate cardiac function in patients with atrial fibrillation is difficult to assess, since the wide fluctuation of cardiac cycle makes the ventricular hemodynamics variable. A new processing algorithm was devised to make multiple gated images discriminated from a heart rate distribution histogram. We obtained about 1,000 beats data by list mode acquisition, and processed a heart rate distribution histogram. The data in the area +/- 5% of the most frequent heart rate were converted into frame mode and a representative time activity curve was derived. Mitral valve area calculated by echocardiography increased from 1.3 +/- 0.5 to 2.0 +/- 0.6 (cm2) significantly (p less than 0.01). The mean transmitral pressure gradient measured by catheterization decreased from 12.4 +/- 5.9 to 4.9 +/- 3.7 (mmHg) significantly (p less than 0.01) and the clinical symptoms improved in all patients. The change in left ventricular ejection fraction from 43 +/- 9 to 48 +/- 13 (%) was not statistically significant, but peak filling rate (PFR) derived from the time activity curve increased from 1.5 +/- 0.3 to 2.0 +/- 0.4 (EDV/sec) significantly (p less than 0.01). Thus PFR is a noninvasive parameter that can evaluate the effect of PTMC.