Expert contributions

Role of (arterial) blood pressure in the human circulatory system

Our heart beats about 60 to 80 times per minute at rest and pumps about 70 to 80 millilitres of blood into the human circulation with each beat. The heart of a healthy person beats about 100,000 times a day and supplies all organs such as the kidneys and brain with the oxygen they need through the flow of about 7,000 litres of blood. The relation between pressure and flow plays an important role in the way the blood is transported through our circulatory system.

The human circulatory system can be divided anatomically into the systemic and pulmonary circulation and functionally into the high-pressure and low-pressure systems. The latter classification is based on the different pressure levels of the respective sections in the human circulatory system. Arterial blood pressure refers to the blood pressure in the high-pressure system. The high-pressure system moderates the blood pressure with the aim of constant organ perfusion (constant, demand-oriented blood flow). In the process, the body’s sensors control the regulation of the arterial blood pressure. The pressure waves generated by the heart are called pulse waves. With the help of the so-called pressure pulse curves, the temporal change of the arterial blood pressure at a measuring point as well as the forward movement of the pulse wave over different arterial sections can be described.

Arterial blood pressure is characterised by the systolic and diastolic values, the blood pressure amplitude and the arterial mean pressure. Learn more about those topics in the following explanations:

Systolic blood pressure
is the highest point of the pressure pulse curve or the maximum arterial blood pressure at a specific measurement point in a cardiac cycle. It results from the ejection of blood from the left ventricle. The optimal systolic blood pressure is ≤120 mmHg.

Diastolic blood pressure
is the lowest point on the pressure pulse curve or the minimum arterial blood pressure at a given measurement point in a cardiac cycle. Diastolic blood pressure is generated by the Windkessel function of the aorta. The optimal diastolic blood pressure is ≤80 mmHg.

 

Blood pressure amplitude (also pulse pressure or pulse amplitude)
Refers to the pressure difference between the systolic and diastolic blood pressure values. This increases towards the periphery. Reason for this is the decreasing elasticity of the arteries from central to peripheral.

Mean arterial pressure (also mean arterial blood pressure)
is the average or mean pressure in the arteries. It decreases slightly towards the periphery. Due to the different length of a pulse pressure curve and the different pressure levels of systole and diastole, the calculation of the arithmetic mean is not sufficient.

Health span – the most important metric for measuring healthy living

For many people, living not only a long and happy life, but also a healthy one, is unfortunately more of a wishful thinking than a reality. In addition to diabetes mellitus, cancer or dementia, cardiovascular diseases in particular are among the most common diseases of the elderly, which massively influence and limit the quality of life of those affected. Worldwide, 17.3 million deaths per year are currently attributable to cardiovascular disease.1 This corresponds to 31 percent of all deaths. Germany records an even higher number of deaths due to cardiovascular diseases, with approximately 36 percent.2  For this reason, they are still considered the leading cause of death worldwide.

Cardiovascular DiseasesDeath per year worldwide (2019)3
Ischaemic Heart Disease8.9 million
Stroke6.2 million
Other2.2 million

At the same time, average life expectancy measured in years has been rising globally for years. In 2019, a person will be 72.6 years old on average. By comparison, the average life expectancy in 2015 was 71.7 years and in 2005 67.9 years.4 So, people are living longer, but are they also staying healthy longer? The question that needs to be asked is how long a person can live within the expected lifespan without health problems or illnesses. A metric that tries to clarify this is called health span. The health span describes the period of time during which a person is healthy within his or her lifetime.

But what does being healthy mean?

Health has different meanings for different people. For this reason, the definition can be extended by the following: health span describes the period of time during which a person is healthy within the entire lifespan, that is, free of any serious and chronic illnesses. In this context, a disease is considered serious if it results in a cause of death, for example, high blood pressure if left untreated. The HALE indicator (Healthy Life Expectancy) of the WHO describes this aspect. Based on current disease and mortality rates, it indicates the average number of years in full health that a person can expect to live.5

The most important step to increase personal well-being and at the same time reduce the risk of serious cardiovascular diseases is a healthy lifestyle. Specifically, this means: a healthy diet with regular exercise and avoiding smoking and alcohol. In addition to these targeted lifestyle changes, the right diagnostic measures taken at an early stage can actively help to keep the cardiovascular system healthy and thus minimise the risk of a heart attack or stroke.

The correct determination of central blood pressure and vascular age offers an enormous additional prevention potential for this and can have a positive effect on extending the health span. Only those who know what the real health values of heart and arteries look like today and can see how they improve with lifestyle changes are motivated to do something for their health before the need arises. After all, it is still true that high blood pressure is one of the most important risk factors for cardiovascular disease that can be influenced. Unfortunately, this also means that untreated high blood pressure not only significantly increases the risk of heart, brain, kidney and other diseases, but also reduces the quality of life of those affected and significantly shortens health span.

 

1 https://www.flipsnack.com/Escardio/esc-cardiovascular-realities-2019/full-view.html
2 https://de.statista.com/statistik/daten/studie/240/umfrage/verteilung-der-sterbefaelle-nach-todesursachen/

3 https://www.who.int/news-room/fact-sheets/detail/the-top-10-causes-of-death
4 https://ourworldindata.org/life-expectancy#:~:text=The%20United%20Nations%20estimate%20a,any%20country%20back%20in%201950.
5 https://www.who.int/data/gho/indicator-metadata-registry/imr-details/healthy-life-expectancy-(hale)-at-60-(years)

Dörr - 2019 - Invasive Validation of Antares to Calculate Central Blood Pressure

Authors: Marcus Dörr, Stefan Richter, Siegfried Eckert, Marc-Alexander Ohlow, Fabian Hammer, Astrid Hummel, Vivien Dornberger, Elisabeth Genzel and Johannes Baulmann

Dörr – 2019 – Invasive Validation of Antares to Calculate Central Blood Pressure