Coronary artery disease remains the most important form of heart disease in the industrialized world. The most common clinical manifestation of coronary artery disease is myocardial ischemia which is characterized by an imbalance between myocardial oxygen supply and demand. This imbalance is usually due to decreased coronary blood flow as a result of critical atherosclerotic obstructive coronary artery disease. With recent advances in technology and evolution of the intravascular Doppler catheter to measure blood flow, a great body of new information has become available about coronary blood flow in health and diseased states. Better understanding of factors influencing myocardial oxygen supply and demand will provide an improved insight into the care of patients with coronary artery disease. This article discusses the factors influencing myocardial oxygen availability and consumption in health and in the presence of coronary artery disease. The factors rendering subendocardium most susceptible to ischemia will also be reviewed. buy asthma inhalers
Supply and Demand
Myocardial ischemia can be defined by the concept of supply and demand. The molecular, physiologic, and clinical evidences of ischemia only occur when demand outstrips the supply of oxygen to the myocardium.