Pressure rate product, also known as Cardiovascular Product or Double Product, is used in cardiology and exercise physiology to determine the myocardial workload.
Rate Pressure Product (RPP) = Heart Rate (HR) * Systolic Blood Pressure (SBP)
with the units for the Heart Rate being beats per minute and for the Blood Pressure mmHg.
Rate pressure product is a measure of the stress put on the cardiac muscle based on the number of times it needs to beat per minute (HR) and the arterial blood pressure that it is pumping against (SBP). It will be a direct indication of the energy demand of the heart and thus a good measure of the energy consumption of the heart.
Rate pressure product allows you to calculate the internal workload or hemodynamic response.
http://www.csecho.ca/wp-content/themes/twentyeleven-csecho/cardiomath/index.php?eqnHD=stress&eqnDisp=rpp http://circ.ahajournals.org/content/57/3/549.full.pdf