Heart attack usually results from a sudden blockage in the arteries supplying the heart.

There are three main blood vessels or arteries which supply the heart. Left anterior descending artery, called the ‘widow-maker’ is the largest and supplies the front of the heart. The other two arteries – left circumflex and the right coronary arteries, surround the heart in the middle and supply the left, right and back sides of the heart (figure 1).



Figure 1: Blood supply to the heart

Cholesterol plaques are formed by certain cells in the blood called macrophages ingesting (or eating) fat globules. This is one of the way body gets rid of excess fat through scavenging. Some arteries are especially prone to have these cells ‘settle’ in the walls of the arteries, heart arteries being one of them. Over time these cells may die and release the fat to the vicinity creating a cholesterol filled plaque (figure 2). This could be an ongoing process which may slowly obstruct the flow downstream. This is like a 4-lane highway progressively becoming 2-lane and finally a single lane highway due to construction.

Figure 2: Deconstructed cholesterol plaque within the walls of the artery

On occasions the plaque may rupture and expose its innards to the blood. The exposed plaque acts as a magnet for platelets and other clotting agents and starts forming a clot. This can result in a sudden and sometimes complete obstruction of the artery. This may happen within a few minutes and results in a heart attack. This is like a 4-lane highway getting totally blocked by a sudden car pile-up. The heart muscles dependent on the artery for nutrition and oxygen supply are suddenly starved (figure 3).

Figure 3: Heart attack zone

A plaque is prone to rupture in presence of risk factors such as smoking or untreated high blood pressure. Read about the other risk factors and treatment.

Symptoms:

Chest pain, shortness of breath, funny-feeling fast heart rate and/or dizziness are the most common symptoms. Chest pain is classically described as dull aching pressure like discomfort, going down the left arm. This textbook description of chest pain however happens in a minority. The pain could be sharp, shooting, stabbing or may have some other unusual characteristics. Some other types of pain, such as abdominal pain, could also signal a heart attack but so could multiple other things. This is where the difficult dilemma comes in, since all the characteristics of pain described above could also be caused by number of other things, some completely unrelated to the heart.

What is done during a heart attack?

An early visit to the closest emergency room is very important because in heart attack the heart muscle starts dying if the blood supply does not start soon. Heart attack may create a certain pattern on the ECG which can be recognized by a healthcare professional. The most common way of opening the obstruction is through ballooning the obstruction with or without stent placement. Alternatively a clot buster may be administered if the procedure is unavailable at the hospital. A good discussion with your physician is emphasized.

One of the common consequences of heart attack is weakening of the heart pump or heart failure. Also read about cardiac arrest and CPR here.

Read about this topic in further details along with diagnosis, treatment and prevention here.

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All opinions expressed here are those of the author and not of the employer. Information provided here is for medical education only. It is not intended as and does not substitute for medical advice.