[Smoking habit and cardiovascular diseases].

The relationship between smoking and ischemic heart disease was discussed, in terms of the smoking habit and the mechanisms of acute and chronic effects of smoking on the cardiovascular system as one of the coronary risk factors, with reference to exercise capacity and coronary flow reserve. The smoking habits of 1000 consecutive patients with ischemic heart disease, who were evaluated with coronary angiography, were analyzed. High percentages of smokers were observed in the younger generation. It was up to 86% in the 4th decade, though it was only 48% in the 8th decade. There was no large difference in other risk factors between smokers and non-smokers. The exercise capacity with and without smoking was evaluated with treadmill exercise test in 6 healthy volunteers. The exercise time was decreased with smoking, compared to without smoking, indicating a decrease in exercise capacity due to smoking. The elevated concentration of carbon monoxide in blood decreased the ability of oxygen transport. The increased lactic acid level in blood with smoking suggested anaerobic energy production acting as a part of the energy source. The smoking increased the myocardial oxygen consumption in relation to increase in heart rate and blood pressure. It decreased coronary flow reserve, shown by a peak to resting flow velocity ratio measured with the Doppler flow velocimeter. In coronary heart disease, therefore, the threshold of myocardial ischemia was decreased by smoking. The decrease in coronary flow reserve recovered with cessation of smoking for more than 2 days.