Effects of a single dose of isosorbide-5-mononitrate on the left ventricular diastolic function in systemic...

The effect of a single dose of isosorbide-5-mononitrate on left ventricular (LV) diastolic function was assessed by radionuclide ventriculography in 18 hypertensive patients. The effect of the mononitrate on atrial filling also was assessed. As expected, there was a significant decrease in mean blood pressure (120 +/- 17 to 102 +/- 18 mm Hg, p less than 0.005). Global LV ejection fraction did not show a significant change, increasing slightly from 64 +/- 9 to 68 +/- 8% (difference not significant). The mononitrate prolonged the time to peak filling rate from 176 +/- 36 to 195 +/- 29 ms (p less than 0.0001). The percentage of time to peak filling rate from diastole also increased, from 46 to 53% (p less than 0.05), whereas the normalized peak filling rate did not change (2.36 +/- 0.6 to 2.31 +/- 0.6 end-diastolic volumes/s, difference not significant). This effect on LV diastolic function was closely related to a certain reduction in preload, as suggested by the reduction in mean left atrial filling (45 +/- 12 to 40 +/- 13 counts/s, p less than 0.005) and LV diastolic counts, suggesting that the "impairment" of diastolic function induced by nitrates is secondary to the reduction in venous return to the left atrium. The mononitrate did not affect the mean right atrial filling rate (50 +/- 12 to 52 +/- 13 counts/s) and the right ventricular end-diastolic counts, suggesting a primary vasodilatory effect of nitrates on the pulmonary vascular bed.