ACUTE HEMODYNAMIC-EFFECTS OF CIGARETTE-SMOKING IN MAN ASSESSED BY SYSTOLIC-TIME INTERVALS AND ECHOCARDIOGRAPHY

Sixteen healthy subjects, ages 18-35 years, were studied in the supine position by means of systolic time intervals and echocardiography before and after smoking a high-nicotine cigarette (2.5 mg nicotine) and a tobacco cigarette of very low nicotine content (<0.02 mg nicotine) to assess and compare the immediate effects upon left ventricular function. Smokers (n=12) and nonsmokers (n=4) behaved alike. High- and low-nicotine cigarettes both caused significant increases in heart rate, systolic and diastolic blood pressure and the triple product (systolic blood pressure x left ventricular ejection (LVET) x heart rate), prolonged LVETc and decreased the preejection period (PEP) and PEP/LVET. In addition, smoking a nicotine reference cigarette increased the echocardiographically derived LV end-diastolic volume of 7.5%, augmented ejection fraction by 4%, while significantly enhancing mean normalized circumferential fiber shortening by 12.5% and mean normalized posterior wall velocity by 9%. Smoking a tobacco cigarette of ultra-low nicotine content resulted in comparable increases in ejection fraction and mean circumferential fiber shortening, albeit on the basis of a significant decrease in end-systolic volume without alteration in end-diastolic volume. These data suggest that in the supine position smoking a high-nicotine cigarette acutely increases venous return and augments the principal determinants of myocardial oxygen consumption - heart rate, contractility, preload and afterload - and that cigarette smoke may contain inotropic and chronotropic substances other than nicotine.