The effect of glyceryl trinitrate ointment on heart rate--corrected systolic time intervals in angina pectoris.

1 Individual systolic time intervals (STI) v heart rate regression equations were determined using small doses of intravenous atropine in seven patients with angina pectoris. 2 Regression lines of the form LVET = A + B.HR and QS2 = C + D.HR were calculated. There was no significant correlation between PEP and HR. The values of parameters A C and D were significantly different from a group of previously studied normal volunteers. 3 STI changes were recorded for 5 h after the application of GTN or placebo ointment. The active drug caused shortening of LVET and QS2 with the peak effect occurring between 105 and 180 min. After 180 min neither LVET nor QS2 were significantly shortened. There was no significant effect on PEP or heart rate.