What is heart enlargement?

Heart enlargement – or cardiomegaly – is a medical condition where the heart’s size spans more than 50% of the diameter of the chest. This is usually caused by cardiomyopathies or the accumulation of previous injuries and poor medical outcomes.

The enlargement can be in one or more of the 4 heart chambers, although the most common type is enlargement of the left ventricle.¹

Causes

Cardiomegaly is characterised by enlargement changes in the cardiac muscle structure. There are many complex causes of cardiomegaly, consisting of a mix of genetic and environmental factors that can slowly build up over time or may occur suddenly by chance. Examples are chronic heart conditions, heart attacks, excessive alcohol consumption, and more. 

The reduction in contractility, relaxation and ineffective energy metabolism results in an unhealthy, enlarged heart with a reduced ability to function normally.¹

Symptoms and physical manifestations

Many patients are asymptomatic at rest and may only experience symptoms when exerting themselves. Imaging the heart via a chest X-ray is currently the only way to diagnose cardiomegaly. If you have cardiomegaly, you may note the following symptoms:¹

• Shortness of breath
• Heart function is adequate during rest but inadequate during exertion when the body’s oxygen and energy requirements increase
• Peripheral oedema (swelling of the feet, legs, or hands) and abdominal distension (bloating)
• Fatigue
• Heart palpitations
• Light-headedness
• Angina – chest pain or discomfort caused by reduced blood flow to the heart
• Nausea and early satiety (some present with anorexia and weight gain)

Other features in your history may include:

• Recent pregnancy or childbirth
• Comorbid illnesses
• Family history of cardiomyopathy

Complications involving cardiomegaly could result in potentially life-altering conditions such as heart failure, blood clots, leaky heart valves (often indicated by a heart murmur), and cardiac arrest.¹

How does weight affect heart health?

Fat is necessary for heart function. Fat is a source of essential fatty acids necessary for life and helps your body absorb fat-soluble vitamins and minerals. In small amounts, it is a healthy and required part of our diet, but too much fat, especially saturated or trans fats, can lead to a variety of health conditions, especially those concerning the cardiovascular system.²

Workload and restrictive heart function

High-fat deposits within the body result in an increased workload on the heart as your body needs more energy to maintain these fat stores. The increased workload without proper exercise to develop heart strength to cope with the increased load results in heart palpitations over time increasing the risk of cardiomyopathies. The increased effort the heart must put in may result in an enlarged heart that is less efficient at pumping blood.

A little fat around the heart helps maintain normal homeostatic function, but too much fat can limit heart function. Fat can cause ventricles to stiffen and cause restrictive cardiomyopathy. This results in a limited ability to relax the heart and allow it to fill with blood, reducing the overall volume of blood pumped with each heartbeat.^3,4,5

Blood pressure and artery blockage

Cholesterol is a type of lipoprotein that is necessary for normal metabolism. However, there is ‘good’ cholesterol or HDL (high-density lipoprotein) and ‘bad cholesterol or LDL (low-density lipoprotein). Higher body fat raises the levels of ‘bad’ cholesterol in your body. Too much cholesterol can alter the width of blood vessels as the fat builds up in ‘plaques’ inside them. This raises blood pressure and puts further strain on the heart and blood vessels. ‘Bad’ cholesterol has been implicated in many heart and circulatory diseases. High blood pressure and the extra strain on the heart can result in heart enlargement (cardiomegaly), and high blood pressure also increases the chance of other factors that lead to cardiomegaly.

The formation of a large plaque can lead to atherosclerosis, which damages the walls of your arteries and activates an inflammatory immune response. This causes fat and immune cells to build up along the damaged area and hardens/narrows the arterial wall, causing even higher blood pressure issues. Atherosclerosis can also cause you to have angina, which is chest pain occurring when the blood cannot pass quickly enough through the constricted vessel, which increases your risk of heart attacks and strokes.^6,7,8

Inflammation

Fat is stored in your body as adipose tissue, which participates in physiological processes such as inflammation. Adipose tissue overproduces and releases pro-inflammatory factors like cytokines. The production of these cytokines contributes heavily to the pathology of heart conditions and physiological changes.

Overall, an increase in unhealthy fats can limit the heart’s ability to function on a variety of levels. There is a direct correlation between obesity and serious heart conditions, including cardiomegaly.^3,5,6,8,9

Weight loss and its impact on heart health

Fat is an energy source it is condensed and stored for later use when the body has low stores of other energy sources such as glycogen (a stored form of the sugar glucose). This means that if you decrease the amount of unhealthy fats in your diet (saturated and trans-saturated fats), your body will use up the fat deposits that are stored. Weight loss has positive effects on the symptoms and risks associated with impaired heart health.¹⁰

Improving heart function

Weight loss reduces the strain on the heart and improves its ability to pump blood. This is because lower tissue mass requires fewer nutrients, blood flow, and oxygen, so the heart has to work less to meet these reduced requirements. This reduces the strain on the heart and can allow it to recover, and remodel back to a healthy structure. 

Engaging in exercise enhances the strength of the heart and increases the robustness of its muscular lining (resulting in thicker heart walls), which boosts both contraction and relaxation. This type of exercise typically falls under aerobic activities and should be designed to suit your individual needs. A more powerful heart can pump blood over the same distance with less effort, thereby easing the strain and workload on the heart. 

Additionally, a reduction in fatty deposits within the pumping ventricles allows the heart to contract and relax more fully, leading to improved blood flow that is both greater and more efficient. All of these factors contribute to an increase in heart chamber size and enhance the heart's ability to circulate blood.^4,11

Reducing blood pressure

Exercise and a healthy diet are both effective methods of improving blood pressure. The heart is made up of smooth muscle cells, and exercising those muscles improves their function. Weight loss helps remove any unwanted and unnecessary fat both in your soft tissues and within the arteries. This leads to an improvement in blood pressure, reduced arterial stiffness, and less force required to move blood around, reducing the strain on the cardiovascular system. Inherently, a healthier system and reduced blood pressure reduce the risks of developing the factors that result in heart enlargement.^7,12

Lowering cholesterol levels

Cholesterol comes in both good and bad forms as mentioned previously and it is produced in the liver. HDL, often referred to as good cholesterol, transports excess cholesterol back to the liver where it is broken down. Increased levels can reduce the risk of heart disease and strokes.¹³

LDL, often referred to as bad cholesterol, is the main type of cholesterol and plays roles such as maintaining cell membrane structure and serving as a foundation for other substances, including sex hormones. An excessive intake of saturated fat can obstruct receptors in the liver, leading to an overproduction of cholesterol, particularly low-density cholesterol, which can cause plaque accumulation and result in various health issues.

Incorporating more unsaturated fats into your diet enhances health and encourages greater production of 'good' cholesterol, helping to eliminate excess cholesterol from the blood and preventing the formation of excessive low-density cholesterol.^7,14

Decreasing inflammation

People with obesity experience elevated levels of inflammation, and losing weight along with decreasing adipose tissue can help in lowering this inflammation, which is crucial for lowering cardiovascular risks. A caloric deficit leads to metabolic changes that lower the inflammatory markers released by adipose tissues, including cytokines. Additionally, a caloric deficit boosts the generation of mitochondria, which are vital to the function of cardiomyocytes, as they generate energy for these heart cells.

These improvements amount to a reduction in heart size and an improvement in heart function.^9,15

Summary

Heart enlargement, known as cardiomegaly, occurs when the heart grows larger than half the diameter of the chest, mainly due to cardiomyopathies or previous health issues. It can affect one or multiple heart chambers. Various causes include chronic heart diseases, heart attacks, and heavy alcohol consumption, which change the heart's muscle structure, leading to a weakened, less efficient heart. Many people with cardiomegaly experience no symptoms at rest and may only feel issues during physical activity. A chest X-ray is the primary diagnostic tool for this condition. Symptoms may include shortness of breath, fatigue, heart palpitations, swelling, nausea, and chest pain. A history of recent pregnancy, other health issues, and family heart conditions may also be relevant. Excess fat can stress the heart and too much fat can lead to stiff ventricles and restrictive cardiomyopathy, impacting the heart's ability to fill with blood effectively. High body fat can raise bad cholesterol levels, leading to artery blockages, high blood pressure, and ultimately, heart enlargement. Conditions like atherosclerosis can further complicate heart health by narrowing arteries and increasing chest pain. To improve heart health, weight loss is crucial, as it reduces strain on the heart and improves blood flow. Exercise helps strengthen the heart and enhance its function. A healthy diet, focusing on unsaturated fats, can manage cholesterol levels and lower inflammation associated with obesity, ultimately benefiting heart size and function.