Increase of intravascular blood volume in Ischaemic heart disease.

Circulating blood volume, cardiac index, heart rate, and ejection rate were measured in patients with angina pectoris. The controls and the patients were divided in sub-groups of those under 45 and over 45 years of age. The investigation was carried out using the isotope method. A significant difference was observed in the value of intravascular blood volume at rest between the controls and patients with ischaemic heart disease unrelated to anginal attack. The blood volume was 5.6 litre in the control group and 6.4 litre in patients with ischaemic heart disease. Exercise tests produced further increases during attack in the blood volume of angina patients. A significant increase of blood volume after moderate exercise was also observed in patients under 45 with ischaemic heart disease but without angina. It is suggested that the increase of intravascular blood volume plays a part in the pathogenesis of angina pectoris.