Electrophysiological effects of felodipine.

Oral felodipine (10mg) was given to 11 patients undergoing routine invasive electrophysiological studies. Systolic blood pressure fell by 31 mm Hg from 130 +/- 17.5 to 99 +/- 10 mm Hg (mean +/- SD, p less than 0.001) while diastolic pressure fell from 78 +/- 9 to 60 +/- 8mm Hg (p less than 0.001), thus confirming its vasodilator properties. Heart increased from 64 +/- 10 to 78 +/- 16 beats/min (p less than 0.001). The A-H interval was significantly prolonged from 97 +/- 14 to 110 +/- 24 msec (p less than 0.01) while there was no change in the H-V interval. Sinus node recovery time showed no change when corrected for heart rate. The effective refractory period of the atrioventricular node was shortened from 317 +/- 38 to 287 +/- 27 msec (p less than 0.01) as was the effective refractory period of the ventricular Purkinje fibres from 251 +/- 18 to 237 +/- 20 msec (p less than 0.005). These haemodynamic and electrophysiological changes suggest that this compound is an effective vasodilator and may have potential antiarrhythmic properties.