Effect of several cigarettes smoked uninterruptedly on left ventricular systolic time intervals in healthy subjects.

The reported investigations were carried out in 50 healthy young men. Twenty of them (group I) performed a three-grade exercise on a Zimmermann cycle ergometer after smoking 4 "Sport" cigarettes, while another 30 subjects served as controls (group II). The exercise was carried out at 60 r.p.m. at a power of 1 W/kg body weight/6 minutes, 2 W/kg/minutes, and 3 W/kg/6 minutes. Between the successive phases of the exercise the subjects rested for 10 minutes. Group I performed work of 148 610 +/- 11 576, and group II--146 632 +/- 19 706 J (p greater than 0.01). The left ventricular systolic time intervals were calculated from synchronous records of the 2nd lead of the ECG, phonocardiogram obtained at Erb's point, and right carotid sphygmogram at rest, after cigarette smoking, immediately after successive phases of the exercise, and during 4 hours after exercise completion. Immediately after smoking 4 cigarettes a decrease was observed in the left-ventricular ejection time index (LVETI), a rise in the value of the pre-ejection period index (PEPI), and a decrease of the left-ventricular mechanical work index (LVET/PEP). These changes evidenced indirectly impairment of myocardial contractility. During the exercise after cigarette smoking no unfavourable changes were observed in left-ventricular pump-like activity in relation to the control group. The restitution period in group I was associated with an increase in PEPI value and reduction of LVETI value which were significantly greater than in controls (p less than 0.01). Despite disturbances in myocardial contractility cardiovascular system restitution was as long as in the control group.