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 by 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.