A calculation sometimes used in cardiovascular research is the rate-pressure pro
ID: 3478046 • Letter: A
Question
A calculation sometimes used in cardiovascular research is the rate-pressure product. This is obtained by multiplying the heart rate by the systolic blood pressure (HR x SBP) This product is used to estimate myocardial VO2. Explain in detail why you think that the double product could provide a good estimation of myocardial work and metabolic expenditure. explain in detail why HR x DBP is not as good as HR x SBP for estimation of myocardial work? Under what conditions could HR x DBP provide a good estimation of myocardial work? Explain in detail.
Explanation / Answer
A myocardial work is generally estimated under intense work not under resting condition. Intense working muscles require greater blood flow than resting muscles. To meet the requirement of greater blood flow, arterial systolic pressure increases. A change in mean arterial pressure occurs which is primarily depend upon the systolic blood pressure which is influenced by the cardiac output and the decreased peripheral resistance caused by vasodilation of the micro-circulation (capillaries).
On the other hand, diastolic pressure in the normal young individual changes very little with exercise and It has also been established that myocardial oxygen consumption ( MVO2) is highly correlated to the product of heart rate and systolic blood pressure in comparison to product of heart rate and diastolic blood pressure.
Thus, in general to estimate cardiac performance, the product of heart rate and systolic blood pressure is taken. This number is known as the Rate-Pressure Product (RPP) or Double Product.
Although in case of resting condition one can use the product of heart rate and DBP because in resting condition there is no occurance of significant changes in systolic blood pressure and therfore one can use either DBP or SBP.
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