Myocardial oxygen consumption (MO2)

Myocardial oxygen consumption (MO2)

Myocardial oxygen consumption is the oxygen consumed by the heart muscle and the determinants of myocardial oxygen consumption are the intramyocardial wall tension, contractility and the heart rate. The double product which is the product of heart rate and systolic blood pressure gives an estimate of the MO2. With every stage of exercise on a treadmill with Bruce protocol is supposed to increase the double product by about forty percent. Sometimes a triple product is also calculated by multiplying the double product with left ventricular ejection time. Effort angina usually occurs at around the same double product each time so that modulating the double product by reducing the rise in heart rate and blood pressure can relieve the angina or elevate the anginal threshold. This is basically by reducing the myocardial oxygen demand in angina of increased demand as is classical of effort angina due to fixed coronary obstruction.