What causes heart attack?


What causes heart attack? It is a million dollar question to many people, worldwide. Heart attack is a painful, life-threatening and often fatal medical condition that needs immediate medical attention. Heart attack is a multi-factorial disease that is clinically classified as modifiable and non-modifiable risk factors. The modifiable risk factors include smoking, alcohol consumption, fat-rich diet, high blood cholesterol levels, sedentary lifestyle, overweight etc. These risk factors can be modified by changes in lifestyle, dietary modifications, medications and physical activity. The non-modifiable risk factors such as age, familial inheritance and gender, can significantly contribute to heart attacks that cannot be modified by lifestyle changes and medical interventions. All the risk factors affect the blood supply to a healthy heart muscles that result in heart attack.

The risk factors contribute to the deposition of cholesterol (plaques) and development of blot clots in one or more blood vessels that supply blood to the heart. If the plaque and blood clots are big, the blood supply to heart muscles is interrupted, and heart attack ensues. If the block is small in size, it results in increased blood pressure or hypertension. If left untreated, uncontrolled blood pressure can lead to heart attack.

Blood Vessels in Heart:

Blood vessels play a vital role in keeping the heart beating. For healthy blood circulation, the blood vessels should not constrict or become clogged with cholesterol deposition. Similar to other muscles in the body, the heart muscles need continuous oxygen supply to keep beating. The heart contains a muscle protein called myoglobin that acts as oxygen reserve during oxygen demand. However, the reserve lasts for only few minutes and interrupted blood supply causes lack of oxygen supply or ischemia that leads to heart attack.

                                   
Blocked Blood Vessels:

Decreased or diminished blood supply results in lack of oxygen supply to the heart muscles that cause myocardial infarction or heart attack. During a heart attack, impaired blood supply causes irreversible damage or death of a portion of heart muscles, which is termed, as infarction. The blocked blood vessel is called as atherosclerotic artery.  

Usually in bleeding process, the body tries to stop the bleeding by the mediation of blood clotting factor called platelet. The platelet adheres with the clotting factors such as fibrin and stops blood oozing by forming a mesh-like structure. This is the body’s natural defense mechanism against blood loss. On the other side, it causes the heart attack. 

Both types of risk factors cause gradual deposition of plaques in large blood vessels. During blood vessel complete block, the body’s immune defense system attacks the plaques to clear the clogged blood vessels. The attack results in unsuccessful clearance of plaques and bleeding of blood vessel walls that cause bleeding. The bleeding process attracts the platelets and blood clotting starts. Within few minutes, the platelets and fibrin completely arrest the bleeding and also the blood supply to heart muscles through blood vessels. This results in diminished blood supply and starvation of oxygen in heart muscles that lead to heart attack. 

In response to death of heart muscles, the nerves in heart cells reacts awkwardly that causes vomiting sensation, sweating, pain, increased heart beats and clammy skin. If one feels these symptoms, it can be a warning sign of heart attack and he/she should seek immediate medical care. Without timely medical assistance, the heart attack victim may die, depending on the degree of heart muscle damage.









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