What are 'holes in the heart' and how dangerous are they?

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What are 'holes in the heart' and how dangerous are they?

Ernest Madu and Paul Edwards

Sunday, January 24, 2021

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“HOLES in the heart” are simple, congenital heart defects and are increasingly being diagnosed since the advent of better, non-invasive cardiac imaging techniques, especially the cardiac ultrasound or echocardiography.

Congenital heart defects are problems with the heart's structure that are present at the time of birth. These defects alter the normal flow of blood through the heart and, depending on the location and size, may present with complications later in life if left unaddressed. Some of these complications may become life-threatening.

HOW DOES THE HEART WORK?

The heart works like a pump and beats 100,000 times a day. The heart has two sides (left and right), separated by an inner wall called the septum. Each side of the heart is further divided into an upper chamber (atrium) and a lower chamber (ventricle), with valves controlling the timing of the flow of blood from each upper chamber to the corresponding lower chamber. With each heartbeat, the right side of the heart receives blood that has been depleted of oxygen from the body and pumps it to the lungs where oxygen enrichment occurs. Following this, the left side of the heart receives oxygen-rich blood from the lungs and pumps it back to the body. The process repeats itself with each heartbeat or cardiac cycle. For normal heart and vascular function, the blood on the right side of the heart that is depleted of oxygen is not designed to mix with the oxygen-rich blood on the left side of the heart. When such mixture occurs, complications become likely. The septum prevents the oxygen-poor blood from the right side of the heart from mixing with the oxygen-rich blood from the left side of the heart. This is essential for normal physiological function.

WHY DO HOLES IN THE HEART DEVELOP?

Some individuals, however, are born with holes in the upper or lower septum. A hole in the septum separating the heart's two upper chambers is called an atrial septal defect (ASD) while a hole in the septum between the heart's two lower chambers is called a ventricular septal defect (VSD).

Doctors know that heart defects present at birth (congenital) arise from errors early in the heart's development, but there's often no clear cause. Genetics and environmental factors might play a role. Children who have genetic disorders, such as Down's syndrome, often have congenital heart defects. Fifty per cent of all babies with Down's syndrome have congenital heart defects. Smoking during pregnancy has been linked to several congenital heart defects, including holes in the heart (ASD or VSD). Because the internal pressures on the left side of the heart are significantly greater than the internal pressures in the right side of the heart, holes in the heart result initially in blood flowing from the higher-pressure chambers on the left heart to the lower-pressure chambers on the right. Blood therefore flows from the left side of the heart to the right side. This means that oxygen-rich blood can mix with oxygen-poor blood.

As a result, some oxygen-rich blood is pumped to the lungs through the pulmonary artery instead of out to the body through the aorta. Over time, if untreated, the pressures in the 'right heart' rise and may exceed the pressure in the 'left heart', resulting in a dangerous reversal of flow of the oxygen-poor blood in the right heart to the left heart, and ultimately to the rest of the body – with potentially devastating consequences. With better imaging modalities, early diagnosis and improved treatment, many individuals with a hole in the heart can get successfully treated early, avoiding the potential adverse complications. Some of the holes may also close spontaneously, without ever requiring intervention. With spontaneous closure or appropriate early treatment, many individuals with a hole in the heart can survive into adulthood and expect to live normal, productive and active lives.

TYPES OF HOLES IN THE HEART

Atrial septal defect (ASD)

As mentioned before, the atrial septal defect is a hole in the wall between the two upper chambers of the heart occurring at birth. Small ASDs are often found by chance following an echocardiogram and may never pose any problems as these small holes may close spontaneously during infancy or childhood. However, large ASDs that are not repaired early would continue to impose significant volume and pressure overload to the right heart and the lungs, and when long-standing can damage these organs. Surgical intervention or percutaneous interventional techniques with device closure might be necessary to repair these large holes early to avoid potential complications.

Ventricular septal defect (VSD)

A ventricular septal defect is a hole in the ventricular part of the septum that separates the right and left ventricles. A VSD allows oxygen-rich blood to flow from the higher-pressure left ventricle into the lower-pressure right ventricle instead of flowing into the aorta and out to the body as it should. This physiological anomaly imposes significant volume and workload on the right heart and the lungs.

RISK FACTORS FOR DEVELOPING A HOLE IN THE HEART

The risk factors for developing a hole in the heart are not well understood. However, as mentioned before, what is known is that some congenital heart defects appear to run in families and sometimes occur with other genetic problems, such as Down's syndrome.

Some conditions that may occur during pregnancy and are known to increase the risk of having a baby with a heart defect include:

•Rubella infection (German measles). Infection with rubella during the first few months of pregnancy is thought to increase the risk of foetal heart defects.

•Alcohol use, drugs, tobacco, or exposure to certain toxic substances. Use of alcohol, tobacco, certain medications, or drugs such as cocaine during pregnancy can harm the developing foetus and may lead to development of congenital heart defects, including holes in the heart.

•Diabetes and lupus. Having diabetes or lupus might increase your risk of having a baby with a heart defect. Pregnant individuals with lupus or diabetes are well advised to have their babies screened early for potential congenital defects, including holes in the heart.

COMPLICATIONS OF LONG-STANDING HOLE IN THE HEART

As said previously, a small hole in the heart (especially ASD) might never cause any problems as these small holes are often likely to close spontaneously during infancy or early childhood. If larger holes are not repaired, though, over time the extra blood flow to the right side of the heart and lungs would likely cause problems. Usually most of these problems do not show up until adulthood, often during or after the third decade of life. Complications are rare in infants and children.

POSSIBLE COMPLICATIONS INCLUDE

Right heart failure

An ASD or VSD causes the right side of the heart to work harder because it must pump extra blood to the lungs. Over time, the extra workload and energy demand may overwhelm the heart, resulting in heart failure and inability of the heart to pump well. This may present as shortness of breath and fatigue at rest or with exertion, and swelling of the legs, feet and abdomen — often associated with weight gain from water retention.

Arrhythmia (irregular heartbeat).

The extra blood flowing through the heart can cause areas of the heart to stretch and enlarge. This can disturb the heart's normal electrical activity, leading to arrhythmia. Arrhythmia symptoms may include palpitations or a rapid heartbeat.

Stroke

Usually, the lungs filter out small blood clots that can form on the right side of the heart. Sometimes a blood clot can pass from the right heart to the left heart through an ASD or VSD, and be pumped out to the body. This type of clot can travel to an artery in the brain, block blood flow, and cause a stroke.

Pulmonary hypertension (PH) is increased pressure in the pulmonary arteries which carry blood from the right heart to the lungs to pick up oxygen, before returning to the left heart for the oxygen-rich blood to be pumped to the body through the aorta. Over time, PH can damage the arteries and small blood vessels in the lungs — making them thick, stiff, and non-compliant and resulting in greater difficulty moving blood through them. As pulmonary hypertension develops, patients begin to experience disabling shortness of breath and severe limitation in activity tolerance.

Growth failure

Particularly noticeable in infancy, a baby may not be able to eat enough to keep up with the body's increased energy demands. As a result, the baby may lose weight or not grow and develop normally, resulting in failure to thrive. This is a phenomenon that is seen with many congenital heart defects.

Eisenmenger syndrome

Over a sustained period and without correction, holes in the heart will lead to sustained pulmonary hypertension, with the pressure in the right side surpassing the pressure in the left side and leading to a reversal of shunt as predominantly oxygen-poor blood flows from the right into the left chamber and ultimately to the rest of the body. This scenario is a potentially fatal, late complication of an untreated, large hole in the heart, and can cause permanent lung and multi-organ damage. This complication, called Eisenmenger syndrome, usually develops over many years and occurs commonly in people with uncorrected, large atrial septal defects. It may result in severe hypoxemia and could lead to death from arrythmia, pump failure or sudden death.

Treatment can prevent or help manage many of these complications. If you have been told that you have a hole in the heart or a “heart murmur”, it is advisable that you consult a cardiologist to obtain an ECG and an echocardiogram, at the very least, to ascertain the true nature of the finding. Our cardiologists at HIC - The Heart Hospital have a lot of experience with this condition and will be able to assist you.

Dr Ernest Madu, MD, FACC and Dr Paul Edwards, MD, FACC are consultant cardiologists at Heart Institute of the Caribbean (HIC) and HIC - The Heart Hospital.

Dr Madu is a main TED speaker whose TED talk has been translated into 19 languages, seen, and shared by more than 500,000 viewers. He has received the Distinguished Cardiologist Award, the highest award from the American College of Cardiology, and has been named among the 100 most influential people in health care and among the 30 most influential in public health. Dr Madu is also a recipient of the Global Health Champion Award from the University of Pennsylvania. Dr Madu is past CEO of HIC and is currently the chairman of IHS Holdings Ltd, an asset management company with interests in the USA, Africa, and the Caribbean.

Correspondence to info@caribbeanheart.com or call 876-906-2107


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