Echocardiography was performed before and after inhalation of 0.9 mg nicotine in 21 patients (6 women and 15 men with a mean age of 51.8 [38-73] years). All of them had angiographically confirmed coronary heart disease (stenosis greater than 50%) and smoked 20-50 cigarettes daily for at least 5 years. In addition, left ventricular filling parameters were determined by transmitral pulsed Doppler ultrasonography. In this technique the flow profile across the mitral valve is divided into the passive, early diastolic inflow (E wave) phase and the active, late diastolic inflow phase caused by atrial contraction (A wave). Isovolumetric relaxation time was measured by simultaneous M-mode recordings over the aortic and mitral valves. The following significant changes were noted after the dose of nicotine (medians; one-sided Wilcoxon test; P less than 0.05): peak velocity of the E wave decreased from 43 to 34.4 cm/s; the ratio between A and E wave peak velocities increased from 1.02 to 1.37; the velocity/time integral of the E wave decreased from 4.77 to 3.57 cm; the ratio between the velocity/time integrals of the A and E waves rose from 0.66 to 1.15; isovolumetric relaxation time increased from 90 to 121 ms. - In cigarette smokers with coronary heart disease, acute administration of nicotine hence caused a decrease in early diastolic transmitral blood flow and an increase in isovolumetric relaxation time. These changes point to significant impairment of left ventricular diastolic function.