How are stroke and heart disease related?
Stroke is often due to sudden loss of blood supply to a region of the brain which usually results in paralysis of a part of the body. Stroke could also be due to bleeding into a part of the brain. Strokes and heart disease are linked together in various ways. In general, risk factors for stroke and some forms of heart disease are similar. Strokes due to blocks in blood vessels, can be seen along with blocks in blood vessels of the heart. Stroke can occur after a heart attack as well. Heart attack damages a part of the heart muscle. This can lead to damage of the inner lining of the heart in that region. A blood clot can form on the inner surface of the heart as a consequence. These clots can break away into the circulation and get lodged into a blood vessel of the brain. The clot thus blocks a blood vessel of the brain and causes stroke.
Another type of heart disease which leads to stroke is an abnormal rhythm of the heart known as atrial fibrillation. In atrial fibrillation, there is a fast irregular rhythm originating in the upper chambers of the heart. The rhythm is so fast that effective contractions of the upper chambers cease. This leads to stagnation of blood in certain parts of the left atrium (upper chamber of the heart), where a blood clot can form. These clots can also get dislodged and travel to blood vessels of the brain. They in turn block a blood vessel of the brain and cause stroke.
Another reason for stroke is high blood pressure. When the blood pressure goes very high suddenly, small blood vessels in the brain may break leading to a bleed into the brain matter. This form of stroke (hemorrhagic stroke) is generally more dangerous than a stroke due to blockage of a blood vessel. Even without a bleed, brain function can be altered due to high blood pressure, causing alteration in the level of consciousness. But then that is not a stroke, but called as hypertensive encephalopathy (brain disease due to high blood pressure).
What are the important risk factors for heart disease?
In general, when we talk about risk factors for heart disease, we tend to think about the most common variety of heart disease in adults – coronary artery disease. Risk factors for heart disease can be divided into modifiable and non modifiable ones. The non modifiable ones are age, gender, ethnicity and family history. The risk of coronary artery disease increases as age advances. So also, the risk is more in males compared to pre-menopausal females. A strong family history of premature heart disease is an important risk factor. Some races are more prone to coronary artery disease than others. Obviously, all these risk factors cannot be modified.
We are more concerned about the modifiable risk factors because that is where the individual and the community can act to reduce the risk. Important modifiable risk factors are smoking, high blood pressure (hypertension), high blood sugar (diabetes mellitus), high body weight (obesity), high levels of lipids in the blood (dyslipidemia) and chronic kidney disease. There are other risk factors as well, though not always checked for – increased levels of homocysteine, fibrinogen, C-reactive protein (CRP) and lipoprotein (a) [Lp(a)] in the blood. Though Lp (a) levels carry significant risk, there are no well established ways of reducing the risk due to it.
What is high blood pressure?
Normal pressure in the main blood vessels arising from the heart is below 120/80 mm Hg. The higher value occurs when the heart contracts and pumps blood and is known as systolic blood pressure. The lower value occurs when the heart relaxes. When the blood pressure is above 140/90 mm Hg, it is usually called high blood pressure (hypertension). Blood pressure varies with age – it is low in a new born baby and rises as the age increases. The values mentioned above are for adults above the age of 18 years. In younger individuals, we have to check with normal blood pressure chart for each age as it is difficult to memorize the values for each age.
What are the symptoms of high blood pressure?
Very often there are no symptoms for high blood pressure and a good number of individuals who have high blood pressure do not know it. High blood pressure is detected during evaluation for other illnesses. Headache, though an important symptom of high blood pressure, is most often due to other causes. Dizziness is another symptom which could occur with high blood pressure. Sometimes an individual comes with symptoms due to complications of high blood pressure rather than due high blood pressure itself.
What are the important complications of high blood pressure?
When the blood pressure goes up very high at a very fast rate, it cause rupture of a blood vessel. This typically occurs in the brain causing bleeding into the brain (cerebral hemorrhage). If a large portion of the brain is damaged due to rapid bleeding, it can lead to sudden death. Otherwise the person gets a bleeding stroke (hemorrhagic stroke), which often manifests with weakness of one side of the body with our without loss of consciousness or difficulty in speaking. High blood pressure can damage the heart, kidneys and the eyes. In the heart it can lead to heart attack and heart failure. Kidneys may fail due to high blood pressure (renal failure). Bleeding into the layers of the eye can occur due to high blood pressure. For that matter, high blood pressure can damage the blood vessels in any part of the body.
What causes high blood pressure?
The most common cause of high blood pressure in adults is unknown and it is called essential hypertension. Other causes of high blood pressure are known as secondary hypertension. Kidney disease, certain hormone disorders, obstruction to blood vessels, diseases of blood vessels and even undue anxiety and stress can cause high blood pressure. Secondary causes are more likely in younger individuals.
These days many are worried about blocks developing in the blood vessels of the heart because it is one of the leading causes of illness and death. Most of the blocks in the blood vessels of the heart do not occur all of a sudden though heart attack is usually an abrupt event. Material which block the vessels including fat deposit develop over a long period of time, just like in an old rusted water pipe. This gradually decreases its lumen size, leading to poor blood supply to the region of the heart muscle supplied by it. But a vessel can get blocked suddenly when one which is partially blocked by fat deposit gets totally blocked by a clot forming over the partial block. This is often the mechanism behind a sudden heart attack, which can even be fatal.
Risk factors for blocks in blood vessels of the heart (coronary arteries)
Risk factors could be modifiable and non modifiable ones. Male gender and advancing age are associated which higher frequency of blocks in blood vessels. These two are important non-modifiable risk factors, along with genetics and ethnicity. Certain families have a higher incidence of heart attacks among their members. Similarly people from some ethnic background are more prone for heart attacks than others.
Though we can’t do much about non modifiable risk factors, there are quite a few modifiable risk factors. The well known ones are high blood sugar (diabetes mellitus), high blood pressure (hypertension), high body weight (obesity) and smoking. Though stress itself does not causes blocks to build it blood vessels, it can act in multiple ways. Stressed individuals are likely to take solace in excessive eating as a method of relief and may become obese. Sudden stress can increase the heart rate and blood pressure which can precipitate a heart attack in an individual already having partially blocked blood vessel. The sudden increase in blood flow speed can cause fissures in the partial blocks which have built up in the blood vessels. This exposes a raw area in the blood vessel where clots can easily form and convert the partial block into a total block.
Risk factor modification by changes in lifestyle is an important intervention in the prevention of heart attack. Reducing total food intake to cut down obesity, regular walking program for physical fitness, restriction of fatty foods and smoking cessation are good time tested methods for remaining fit.