The use of color Doppler ultrasound in exercise testing

Abstract

Vigorous exercise of the large skeletal muscles produces an increase in myocyte oxygen demand which must be satisfied by an increase in cardiac output of up to, even exceeding, 500% in normal individuals. Since this is accomplished by a combination of increased heart rate and contractile force, myocardial oxygen demand also rises, and this demand, in turn, is satisfied by an increase in blood flow in the coronary arteries. In patients with ischemic heart disease, this increased flow produces a pressure drop distal to any narrowed coronary arterial segment. If this pressure drop is large enough, transient myocardial ischemia will result. Such ischemia causes changes in both electrical and functional properties of the heart muscle, and since these changes may be detected non-invasively in various ways, exercise stress testing has been useful in the detection and assessment of ischemic heart disease since 1931 [1].