Radionuclide ventriculography: acute and chronic response to verapamil in patients with hypertrophic cardiomyopathy.

Eleven patients with hypertrophic cardiomyopathy were investigated by repeated radionuclide ventriculography. Nine of them were studied for the first time while under long-term treatment for 14 to 84 months. In all eleven patients radionuclide ventriculography was performed after a withdraw of verapamil for at least 14 days or before the onset of therapy respectively (control period). A third investigation was carried out 60 to 90 min after acute administration of 90 mg oral verapamil. A last radionuclide ventriculography was performed following 2 weeks of therapy with 480 mg oral verapamil. After acute administration heart rate significantly increased from 69 +/- 10 to 80 +/- 15/min. EDV was in the normal range. Left ventricular global ejection parameters showed no significant changes except for minimal decrease in ejection time from 309 +/- 29 to 278 +/- 50 ms after acute verapamil administration. The sectorial ejection fraction improved in apical sectors in relation to the basal one, while the global EF remained constant. The ventricular global peak filling rate increased significantly from 283 +/- 61 to 325 +/- 64%/EDV/s after acute administration of verapamil and the sectorial peak filling rate increased in apical sectors compared to basal sectors following acute administration as well as long-term therapy. After withdrawal of verapamil, six out of 11 patients showed a homogeneous left ventricular delay of contraction by means of the Fourier phases which were normalized under short- and long-term verapamil treatment. In conclusion, verapamil caused a marked improvement of the left ventricular contraction delay without significant changes in global systolic function.