Blood Pressure and Pulse
The regulation of blood pressure in the body is subject to complex mechanisms that are not yet fully understood. Nevertheless, the most important factors leading to the development of high blood pressure are known today. It is clear that there is not just one reason why blood pressure becomes too high. The causes of the most common form of hypertension, essential hypertension, can be found both genetically and in individual lifestyle factors, such as unhealthy diet, lack of exercise, obesity, and also chronic stress. Part of these regulatory mechanisms is influenced by hemodynamic factors (pressure in the vessels). The pulse describes the number and intensity of impulses sent out by the heart, which can be felt in the arteries and is given per minute. It plays a crucial role in the pressure conditions in the blood vessels. However, heart rate and pulse rate can also differ if not all beats are strong enough to trigger a pressure wave in the arteries.
Hemodynamic Factors of Blood Pressure Control
The three reference values of hemodynamic blood pressure control are heart rate (or pulse rate), stroke volume, and peripheral resistance. The heart rate is in a normal range of 60 to 80 beats per minute. Stroke volume is the amount of blood ejected from the heart into the periphery per systole. This averages 70 milliliters or 0.07 liters. Cardiac output is the product of stroke volume and pulse. This means that with a pulse of 60 beats per minute, more than four liters of blood are processed by the heart, which corresponds approximately to the total blood volume of the body (about five liters on average).
Blood pressure (RR) is the product of cardiac output and peripheral resistance (flow resistance). The formula can be simplified as follows: RR = HR x SV x PR (HR = heart rate; SV = stroke volume; PR = peripheral resistance). This formula allows for the explanation of certain hemodynamic behaviors of one or the other measurement value. An observed phenomenon is, for example, the sudden acceleration of the pulse after the administration of antihypertensives (blood pressure-lowering medications), which lower peripheral resistance in the tissues by causing vasodilation (so-called alpha-blockers). A decrease in peripheral resistance brings about a simultaneous decrease in blood pressure according to the formula. The body then compensatorily increases heart rate and, to a limited extent, stroke volume. This mechanism explains why tachycardia ("racing heart") is listed as one of the most common side effects in the package inserts of alpha-blocker type antihypertensives.
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Athletes have well-trained heart muscles that produce an increased stroke volume. Instead of the average 70 milliliters, these hearts pump 100 milliliters or more per heartbeat. Since the body must circulate about four to five liters of blood at rest to adequately supply all organs with blood, athletes have a low resting pulse rate, as their heart only needs to beat 45 to 50 times per minute with a stroke volume of 100 milliliters to achieve the required output of four to five liters (cardiac output). The positive effect of a lowered pulse rate lies in the significant extension of diastole, i.e., the filling times for the heart chambers and coronary arteries of the heart.
Sources:
- https://www.kup.at/kup/pdf/12347.pdf
- https://www.internisten-im-netz.de/fachgebiete/herz-kreislauf/begriffe-rund-ums-herz.html
- http://physiologie.cc/VII.1.htm
- https://www.thieme-connect.de/products/ebooks/lookinside/10.1055/b-0034-5311
- https://www.msdmanuals.com/de-de/heim/herz-und-gefäßkrankheiten/sport-und-das-herz/das-sportlerherz
By Sabine Croci.
This article is medically reviewed. Last updated (11/2024).
Information on the website and within the app cannot replace a consultation with a doctor, but can certainly complement it.
