The Function of the Circulatory System With Special Reference to Hemodynamic Studies of Heart Failure

Cardiac performance is the most important function of the circulatory system. It is represented by regulation of cardiac output. The normal heart can increase its output to as much as more than 10 times that in resting state. The heart responds to a slight increase in the demand for cardiac output by increasing heart rate, while it responds to a moderate or marked increase in the demand by increasing not only heart rate but also stroke volume. In heart failure, cardiac output cannot satisfy the demand of the body tissues at rest or during exercise. The present study dealt with hemodynamic changes in heart failure and the effects of several drugs on the hemodynamics in heart failure.Investigations have been performed by means of left heart catheterization. Radioisotope dilution method has been used for the determination of left ventricular volume.The subjects examined were divided into 4 groups according to the severity of heart failure : subjects without heart disease (" control " group), patients with heart disease without heart failure ("without failure" group), those with mild failure ("mild failure" group), and those with moderate to severe heart failure ("severe failure" group).