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Trouble in the house

Think of the heart as a house, and it becomes easy to understand the various ailments that plague it. Just as a house can have structural, mechanical, electrical and plumbing problems, so can the heart. The ‘plumbing’ problems of the heart are by far the most common. These are blockages that take place inside the coronary arteries, leading to angina, heart attack, and even death. In medical terms, it is known as coronary heart disease or coronary artery disease.

Electrical problems

Each time your heart beats, or contracts, it does so in a synchronized manner, such that the atria and ventricles work in co-ordination. Electrical impulses spread through the heart in an organized manner. When they are transmitted haphazardly, you may feel uncomfortable beating sensations in your chest, which we commonly refer to as palpitations. Depending on their frequency and nature they can be harmless, which most of them are, or they can be life-threatening. A pacemaker is often implanted to solve the rhythm problems of the heart. ​

Mechanical problems

The heart’s valves permit the flow of blood in one direction only. It is possible that, over time, the valves may either get too stiff or too loose. If they are too stiff, they will not open freely, and this hampers the flow of blood. If they are too loose, they will flap back and allow the backflow of blood. In either of these conditions, adequate blood flow to the body will be compromised and the person may develop symptoms such as breathlessness. If either of these conditions is severe, the valve may need to be surgically repaired or replaced. ​

Structural problems

The human heart is typically formed in the foetus within four to seven weeks of pregnancy. In rare instances, during formation, there may be abnormalities in the structure of the heart. These may manifest soon after birth or sometimes remain undetected for several years. The most common one is a hole in the heart. In a normal heart, the right and left chambers are separated by a wall, so that the impure and pure blood do not mix. When there is a structural defect (opening) in the wall, it is referred to as a hole in the heart. This allows impure blood to enter the aorta and get pumped to the rest of the body. Mixing of pure and impure blood gives a bluish tinge to the skin, and hence the term ‘blue baby’ is sometimes used to describe congenital heart disease. Depending on the size of the opening, it may need to be operated to close it or may be left open and followed up with close medical supervision.

Plumbing problems

The heart pumps blood to the whole body for its survival, but at the same time, it needs to pump some of that blood back to itself for its own functioning. Coronary arteries run on the outer surface of the heart and supply blood to the heart muscle to allow it to pump efficiently. Blockages in the coronary arteries are what we conversationally refer to as heart disease. Due to these blockages, known as plaques, the heart muscle receives inadequate blood supply. Heart disease is the largest cause of death in the world, both in men and women. The formation of this killer disease takes place over several years and can therefore be halted if adequate preventive measures are taken in time. ​

How plaque causes heart attack

Plaque is made up of cholesterol, calcium, dead materials from cells, and fibrin (clotting material present in the blood). Conventional thinking was that this plaque grew slowly over time, and ultimately became large enough to stop the flow of blood to the heart muscle and cause a heart attack. However, over the last couple of decades, we have learnt that at some point in its growth, the plaque cracks or ruptures, and that causes a large blood clot to be formed at the area of rupture. This blood clot obstructs the flow of blood, leading ultimately to the death of a part of the heart muscle: a heart attack.

Size does not matter: 70 per cent blockage may be more dangerous than 100 per cent​

The perfect storm

In late 2012, a study was published which changed our understanding of how heart attacks occur. The study revealed that for an acute coronary event to occur (such as heart attack or death), multiple factors need to fall into place at the same time, leading to ‘the perfect storm’. The factors and conditions associated with an increased risk for events include the composition and size of the plaque, blood clotting factors, hormonal influences, risk factors, and environmental factors such as pollution.​

Heart failure

Heart failure is a condition in which the amount of blood pumped out by the heart each minute is not enough to meet the needs of the body. This usually occurs when the heart muscle is weak and is unable to pump out sufficient blood. The commonest cause is coronary artery disease (with or without a heart attack). Other common causes are high blood pressure over a period of time and cardiomyopathy—when the heart muscle is weakened by becoming enlarged, thick, or rigid.

Patients with heart failure may be in a stable phase and live for a very long time, with no symptoms, while a few may go into an acute phase in which they feel extremely short of breath and may need to be hospitalized for a few days. The percentage of blood pumped out is called the ejection fraction or EF. A normal EF is considered to be between 55–65 per cent, while in heart failure patients it can be as low as 15–20 per cent.

Often the pumping capacity or ejection fraction of a heart failure patient is greatly reduced. During the relaxation phase of the heart cycle, the left ventricle fills with blood, which is pumped out during the contraction phase. However, all of the blood is not pumped out, and some remains inside the left ventricle.

The focus is on blockages

As you have seen by now, the heart can suffer a plethora of problems from birth to death. However, when we talk about heart disease, we refer to blockages in the heart arteries. The next few articles will focus on the prevention, reversal and treatment of these blockages, since it’s by far the most frequently prevalent form of heart disease.​

Take-home messages

• Problems of the heart can be broadly grouped into electrical (pacemaker), mechanical (valve), structural (hole in the heart) or plumbing (blockage).
• When we talk about heart disease, it usually refers to coronary heart disease, which is the formation of blockages in the coronary arteries.
• The process usually takes place over several years, due to the deposition of cholesterol and other ‘junk’ substances in the inner lining of the coronary arteries.
• A heart attack takes place due to a rupture in the blockage. The stability of the blockage matters more than the size, which is why a larger blockage is not necessarily more dangerous than a smaller one.
• Heart failure is a condition where the heart is not able to pump adequate blood to meet the demands of the body​.

This article is part of a series of articles on the ​prevention, treatment, and reversal of heart disease by Dr Aashish Contractor.​