When someone is diagnosed with an enlarged heart, it can often be a sign that there is some form of stress being put on the cardiovascular system. This is known as cardiomyopathy– a disease of the muscle of the heart. This then affects the normal function of the heart and its ability to pump blood around the body.

With normal blood flow affected, a person's general health can worsen, as all systems would be less effective due to the body supplying oxygen and removing waste less efficiently in those with an enlarged heart, as with most heart issues. Blood pressure is an easy way to track heart health and see how well the cardiovascular system is working. So, in those with any form of heart problem, monitoring blood pressure is key in the care of these conditions.

What is heart enlargement?

An enlarged heart (cardiomegaly) is not in itself a disease, but rather a symptom of a disease that affects the heart and cardiovascular system as a whole. These diseases are referred to as cardiomyopathies, meaning that it is a disease that affects the muscles of the heart, in particular causing stretching and enlargement.

The cardiomyopathy that causes heart enlargement would be called hypertrophic cardiomyopathy. This condition affects the muscles of the heart, particularly the main pumping chambers (left and right ventricles). These muscles have to work harder, so they become thicker in an attempt to push the blood out of the heart and to the rest of the body.¹ 

Dilated cardiomyopathy is another cause of heart enlargement; rather than the muscle becoming thicker, the chamber of the heart becomes stretched out, causing the overall size of the heart to increase. The wall being stretched affects its ability to properly pump oxygenated blood to the body.² 

Any cardiomyopathy can cause enlargement of the heart, the main result being the heart's lessened ability to effectively pump blood around the body.

High blood pressure is a major part of what can cause an enlarged heart, high blood pressure means that there is less efficient transport of oxygen through the blood; so the heart must further increase the flow of blood to try and boost oxygen being transported, this can put a greater strain on the heart causing the muscle to enlarge (causing the heart muscle to grow thicker).³ 

Other diseases such as congenital heart disease, birth defects or a family history of cardiomyopathy, can be risk factors for an enlarged heart and would be considered in the diagnosis and management of any cardiovascular condition.

Symptoms of an enlarged heart

People with an enlarged heart may experience symptoms such as:

• Dizziness
• Oedema, particularly in the lower legs, water collects and causes swelling
• Shortness of breath
• Irregular heart rhythm (arrhythmia)

These symptoms are similar to many other cardiovascular conditions, especially those linked to high blood pressure. An enlarged heart may not always present with obvious external symptoms, and the enlargement itself may not be visible without imaging. As a result, it can be difficult to identify without medical tests.⁴ 

Diagnosis

There are many potential diagnostic tools for a doctor when diagnosing an enlarged heart, these are:

Blood tests

These can be used to identify what conditions may be causing the heart enlargement. They can also help detect damage to the heart muscle caused by a heart attack, especially if the enlargement occurs alongside chest pain.

X-ray imaging

An X-ray of the chest can show an enlarged heart, however, other tests would occur to confirm the heart enlargement and possible causes.

Electrocardiogram (ECG or EKG)

Using electrodes placed on the skin, around the chest, the electrical signals of the heart can be detected to understand the speed at which the heart is beating and look for signs of a thickened heart wall.

Echocardiogram

Ultrasound is used to develop a picture of the heart and how the blood flows through it and is pumped; it can help create a picture of how the heart is functioning.

Computed tomography (CT) and Magnetic Resonance Imaging (MRI)

These are more accurate methods of imaging that can create a more complete image of the heart and can help diagnose an enlarged heart.

Diagnosing an enlarged heart may not be as simple as just using imaging techniques. Although they are important, other tests may be required to get to the root cause of what is causing the cardiac issues. All these tools are used to confirm an enlarged heart and the underlying cause.³ 

Blood pressure and enlarged hearts

Blood pressure and heart enlargement have a very close relationship, in that high blood pressure can cause or exacerbate an enlarged heart whilst also being symptomatic of other conditions.

Controlling blood pressure may help in preventing or reducing the progression of an enlarged heart.

This works as high blood pressure can cause damage to the heart; causing stress and damage, leading to the enlargement of the heart. High blood pressure may not be the only cause of heart enlargement, as it can also be a symptom of an underlying cardiac disease.

The best way to manage or prevent high blood pressure is to manage lifestyle choices, particularly diet and exercise. This can help reduce high blood pressure and therefore reduce the risk of what is a potential cause of an enlarged heart. High blood pressure can also be controlled with the use of medications, such as beta-blockers or ACE inhibitors, that would be prescribed to someone with hypertension (high blood pressure). 

This can be important to reduce the stress on the heart and allow it the chance to heal and avoid further damage, this would be useful in cases where blood pressure is the main cause of cardiomegaly, in other cases, management of blood pressure may not necessarily help the enlarged heart but would help reduce risk of any further cardiovascular damage.⁴ 

Summary

An enlarged heart can be caused by many different conditions; diseases that are called cardiomyopathies in particular, which affect the muscles of the heart causing enlargement.

High blood pressure can be a main cause of heart enlargement as this causes stress for the heart so it must then stretch and thicken to push the blood around. 

The symptoms are similar to many cardiac diseases, causing dizziness, oedema, shortness of breath and an irregular heartbeat.

Diagnosing an enlarged heart can be done using a range of techniques in particular imaging techniques (CT scan, MRI or x-ray) to create a picture of the heart and understand the structure of the heart. Blood tests may also be done to rule out or confirm what is the cause of the high blood pressure and heart enlargement.

Blood pressure can be the cause of heart enlargement and further exacerbate the issue due to increasing stress on the heart.

Blood pressure can be managed by simple lifestyle changes such as a healthy and low-sodium diet, stopping smoking and exercising regularly. This could help prevent high blood pressure or reduce blood pressure. In those with heart enlargement caused by high blood pressure, this may help to reduce the stress on the heart and support healing, potentially improving heart size and function.

This could also be done with the help of medications that are prescribed to those who have hypertension (high blood pressure).