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You might have heard the normal blood pressure is 120/80 mm of Hg. After visiting a doctor for some reason, he says "You have a high blood pressure 160/110." or sometimes "You have a low blood pressure 90/60." A doctor just assumes that you must have some idea about blood pressure and doesn't bother to explain it further. But in reality, most of the people have very little idea of what it actually is.
Image by rawpixel, Wikimedia, Public domain
According to World Health Organization(WHO), almost 1.1 billion suffer from hypertension and most of them (Almost two third) are from low or middle income countries. Almost 1 in 4 men and 1 in 5 women have hypertension and also, one of the leading cause of premature death.
In this article, I will explain what blood pressure actually is, meaning of 120/80, talk about hypertension and how it can lead to heart failure.
Blood pressure and Water Pipes
You can imagine, blood vessels as a tube. Blood which is being constantly pumped by the heart tries to get to the other side through these tubes. Now, think of moving blood exerting some force on the wall of the tubes(blood vessels). This force is called as Blood pressure.
Simply, you can compare this mechanism with water flowing through pipes. So, what factors would determine the force on the wall of the water pipes? Obviously, the force of the flowing water and diameter of the pipe. Right?
If the diameter is less, then the force will be greater and vice versa. If the force of the flowing water from the source is high, then it will exert more pressure on the wall of the pipe. You can use this analogy to understand blood pressure
In terms of blood pressure, we can now say, the force on the walls of blood vessels can be determined by two factors:
- Cardiac output
- Total peripheral resistance- diameter of the blood vessels
Cardiac output:
This shows amount of blood is pumped by the heart in a minute. Just like the example of water pipes, in this case the heart is the source which determines the force and volume of the moving blood. If the cardiac output is more than the blood vessels will be loaded and exert more pressure. In clinical practice, we use this formula to determine the cardiac output.
Cardiac output = heart rate X Stroke volume
Stroke volume means how much blood is ejected from the heart in each contraction or in each heart beat. Which is usually about 50-100 ml. Heart rate is just the number of contractions per minute. The normal heart rate is more or less 72 beats per minute. According to the formula given above, the estimated blood output would be more than or equal to 5 liters of blood each minute.
Total peripheral resistance
Total peripheral resistance is the resistance created by the blood vessels with less diameter to maintain the flow of the blood. Imagine, if the water is pushed through the narrow pipe, the speed and force of the water increases. The same phenomenon happens in the blood vessels.
So, now we can view the blood pressure in terms of cardiac output and total peripheral resistance. Therefore, we can use this formula to determine it:
BP or Blood Pressure = CO or Cardiac Output X TPR or Total Peripheral Resistance
If any one of the given factor increases, it will increase the blood pressure leading to hypertension.
The Actual meaning of 120/80
Every one must have heard this number at some point. Here, 120 and 80 both represent the different type of pressure exerted on the wall of the blood vessels by the blood. 120 represent the systolic blood pressure, whereas 80 represents the diastolic pressure. What is that?
Systole and Dystole by Bruceblaus, Wikimedia, CC By-SA 4.0
Systolic blood pressure means the pressure exerted on the walls by the blood during the contraction of the heart. Similarly, diastolic blood pressure means the pressure exerted during the relaxation of the heart. When the heart contracts more blood is pushed hence more pressure(systolic) is seen and when it relaxes, no blood is pumped hence less pressure(diastolic) is seen.
Systolic pressure can also increase in the conditions like fear, nervousness, excitement, etc. as the heart pumps more blood in these conditions. But a severe increase in diastolic pressure is only seen when arteries are heavily narrowed. Therefore, more caution should be given to diastolic rather than systolic.
Factors for Hypertension
Any measurement above 140/90 mm of Hg is considered as Hypertensive state. Sometimes the symptoms are very vague, a person might experience just a headache, mild confusion, mild visual disturbances or bleeding nose. However, sometimes there might be no symptom at all. You may be doing your daily activity with a very high blood pressure with absolutely no symptoms. This is why, regular Blood pressure checkup is important.
But, what are the factors leading to hypertension?
I described a formula for blood pressure.
BP or Blood Pressure =CO or Cardiac Output x TPR or Total Peripheral resistance
we understand, what factors increase the values of cardiac output and total peripheral resistance, then we can see the rise in blood pressure.
Factors Increasing Cardiac Output
Since it depends on stroke volume and heart rate. We need to look at things that increase those:
Increase stroke volume or blood volume: When the contractility of the heart increases as in exercise the blood volume ejection also increase. Other examples are hyperparathyroidism, adrenergic drugs and some diseases, increasing the blood volume.
Increase in Heart rate: Emotions and anxiety can obviously raise your heart rate, body temperature, dehydration, illness and medications are some other examples.
Factors increasing Total peripheral resistance
Total peripheral resistance depends on the diameter. So, we need to look at factors to decrease the diameter that increases the pressure. Some factors are High cholesterol levels. As the cholesterol gets deposited on the wall of the arteries as plaques, it narrows them increasing the pressure. Also, high sodium content increases the stiffness of the arteries leading to temporary hypertension.
Old age is also a major factor, the arteries gets more stiffed with increasing age.
Hypertension and Heart Failure
Well, a temporary rise in blood pressure is not that harmful. But, if that becomes chronic, it can have some serious effect on the heart. If your BP is not under control and the extra pressure which is absolutely not supposed to be there, starts to destroy the whole flowing system of the heart.
We can understand it in two ways. The higher pressure can damage the both, the pump which is the heart and the pipes which is the blood vessels.
Heart failure by damage to the heart:
It's pretty simple. The heart pumps blood through the arteries. In hypertensive state, the arteries already have high pressure. The heart can't stop, it has to get the job done. Therefore, it needs to generate the force to pump out the blood against the already high arterial pressure. In the short term, it doesn't make much of a difference, the heart can do it pretty easily. But, if we look at the long picture, the heart has to pump harder and harder. This would not be possible without some physical change in the heart itself.
What physical change can make the heart pump harder? Well, if the muscles of the heart get stronger or bigger, it certainly can pump the blood against the pressure and the resistance. This change is known as "Hypertrophy" of the muscles. You might think that's good for maintaining blood flow. But, that's not the case. When the muscles of the ventricles get bigger or hypertrophied the blood is pumped even less effectively. You see, there is not enough room left inside the ventricle for blood. With time, this gets worse, the heart becomes incapable of pumping blood leading to manifestation of heart failure.
Heart failure by damage to Arteries
It's a little different from damage to the heart, but the concept is same. When the pressure stays above 140/90 for a longer period it can make small tears in the arterial walls. The tears in the walls can be very dangerous. This tear can lead to inflammations of the wall. Substances like WBC or white blood cells responds to the inflammation and starts collecting around the small tears. The cholesterol and the fat molecules in the blood also gets deposited. This forms a plaque around the tear and inflamed area. This plaque eventually thickens and hardens the arterial wall, leading to a condition "Atherosclerosis"
Whenever this plaque ruptures, blood clots might start forming over the tear causing the blockage of the artery. Clot not only blocks the artery, it blocks the oxygen supply too. If all of this happens in the coronary artery (Artery supplying the heart), the heart will be deprived of oxygen and nutrients leading to heart failure.
Prevention of Hypertension
Your diet and your lifestyle play a major role in the prevention of hypertension. Anyone can suffer from this, but there are some certain risk factors. You can see if you are at risk or not:
- Age: risk of hypertension increases with age. Must be careful above 35.
- Weight: Obesity is the leading factor for plaque formation and hypertension.
- Gender: Men are more likely to develop hypertension before the age 55.
- Lifestyle: Lack of exercise, too much alcohol, smoking, fast food, too much salty food, etc leads to hypertension.
- Family history: This raises the risk of hypertension if your parents had it. But it is preventable.
Some Lifestyle Modifications to prevent it
Regular Exercise is the best:
A regular physical activity or moderate exercise can lower your blood pressure by 5-8 mm of Hg. Believe me, that's a lot. It is recommended for 30 minutes of physical activity for at least 5 days a week for a better lifestyle and prevention of hypertension.
Healthy diet is your friend
If you are at risk, then you must consider your diet. Your diet must contain very little salt (sodium) and more potassium. Also, food containing more fats and cholesterol must be excluded. Start taking plenty of fruits every day. There's something called Dash eating plan which is basically a diet plan to stop hypertension.
The plan:
- vegetables, fruits and whole grains.
- Low fat dairy products.
- Exclude the high saturated fat products like fatty meats, fatty dairy products, palm oils, etc
- Don't exclude the sugar but limit it.
Healthy weight:
Being overweight, obviously increases the risk. As, high level of fats and cholesterol can deposit in the arteries making it narrower. Therefore, weight management is very necessary.
Limiting Alcohol and Smoking
Several studies have shown consumption of alcohol leads to sympathetic nervous system activation leading to a temporary spike in blood pressure. This usually returns to normal after some time. But, if the alcohol consumption is chronic, it can lead to chronic hypertension. Therefore, the best bet is no more 1 to 2 drinks a day.
Smoking a rapidly produce spike in blood pressure. Nicotine is the main problem here. It not only raises the blood pressure, but increases the heart rate and hardens the arteries too.
Manage your stress.
Learning to improve your mental health and to relax can drastically lower your blood pressure. Some activities to be considered are meditation, yoga and music.
That's it for this article guys. I hope you got something new today.
*All images used are copyright free.*
References:
[1]https://en.wikipedia.org/wiki/Hypertension
[2]https://en.wikipedia.org/wiki/Blood_pressure
[3]https://www.who.int/news-room/fact-sheets/detail/hypertension
[4]https://www.cdc.gov/bloodpressure/index.htm
[5]https://www.mayoclinic.org/diseases-conditions/high-blood-pressure/in-depth/high-blood-pressure/art-20045868
[6]https://www.lark.com/blog/prevention-of-hypertension/
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