Introduction

A beating heart creates pressure in the blood vessels (arteries) that helps push oxygenated blood into the body. The pressure is created with each heartbeat as blood is pumped into the arteries from the heart. In medical terms, pressure or force is referred to as tension. Hypertension is high blood pressure, and chronic hypertension is persistently high or raised blood pressure. Chronic hypertension directly increases the risk of a heart attack or stroke.¹ In this article, we will understand what chronic hypertension (high blood pressure) is and how it can contribute to heart enlargement and result in a heart condition. 

An enlarged heart, that is, cardiomegaly, denotes an increase in the size of the heart. It is a sign that your weakened heart is trying to compensate and pump enough blood to your body.

Understanding chronic hypertension

As the heart continuously pumps blood to the body through the blood vessels, it is natural for a force or pressure to be created. This force pushes the blood to the entire body. The blood pressure is read by using two readings–the systolic and diastolic blood pressure. It is commonly expressed as a ratio of the systolic blood pressure (pressure exerted by the blood on the walls of the blood vessels as the heart contracts) and diastolic blood pressure (pressure when the heart contracts).⁵ Normal blood pressure is anything less than 120/80 mmHg. Anything above the normal level is considered high blood pressure or hypertension.

The National Heart, Lung, and Blood Institute (NHLBI) of the National Institutes of Health (NIH)³ has determined two levels of high blood pressure in adults:

Stage 1:

• Systolic pressure: 140 to 159 mmHg
• Diastolic pressure: 90 to 99 mmHg

Stage 2:

• Systolic pressure: 160 mmHg or higher
• Diastolic pressure: 100 mmHg or higher

Causes and risk factors of chronic hypertension

Genetic factors

Research suggests that hypertension runs in families because of specific genes associated with the condition.⁶

Age

Blood vessels lose their elasticity and become stiff as we age and increase blood pressure. 

Lifestyle choices 

• Diet: Unhealthy foods, high in salt and sugar and loaded with fats, excessive alcohol and caffeine consumption are all important dietary factors that may cause hypertension
• Exercise: A sedentary lifestyle, lack of exercise or any form of physical activity results in the accumulation of excessive fat, leading to the thinning of the blood vessels and increasing the blood pressure
• Stress levels: High stress levels, anger and lack of quality sleep all contribute to an increase in blood pressure
• Medicines: Certain medications and drugs tend to make it difficult for your body to regulate blood pressure

Other medical conditions

Conditions that may lead to hypertension are:

• Obesity
• Thyroid 
• Chronic kidney disease
• Metabolic disorders
• Sleep apnea

Race and ethnicity

Research suggests that hypertension is more common in Black adults than White, Hispanic or Asian adults.

Gender

Men are more prone to the development of hypertension than women in middle age; however, in the older age group, especially post menopause, women are more likely to develop hypertension than men in the same age group.

Socioeconomic factors

• Income
• Education
• Societal status
• Profession 

Mechanisms of chronic hypertension

The risk factors and causes mentioned above play a vital role in the development of chronic hypertension. While certain risk factors, like lifestyle and stress levels, can be managed by the individual, genetics cannot be controlled. Following unhealthy habits over a long period and underlying health conditions can cause weakening of the heart muscles. Chronic hypertension can cause serious damage to the heart muscle and blood vessels. These include:

• Heart enlargement
• Damage to the arteries (Coronary Artery Disease)
• Irregular heartbeat
• Heart failure
• Stroke
• Metabolic disorder

The blood vessels have greater resistance against the blood flow in individuals with hypertension, which causes the heart to pump harder in order to circulate the blood to the entire body.

Relationship between chronic hypertension and heart enlargement

Heart enlargement (Cardiomegaly) is an increase in the size of the heart. Conditions such as hypertension can thicken the heart muscle or stretch the chambers of the heart, which makes the heart enlarged.

Heart enlargement happens in two ways:⁷

Dilatation

The walls of the heart are stretched and become thin or weak. This makes the heart appear enlarged.

Hypertrophy

The walls of the heart thicken by adding extra layers of muscle to compensate for the extra workload. 

An enlarged heart by itself is not a disease but a sign of another underlying serious condition. Cardiomegaly, or an enlarged heart, is observed through diagnostic imaging tests like X-rays.⁹

Heart enlargement can also be caused by Cardiomyopathy, a disease of the heart muscles that makes it harder for the heart to pump blood effectively.

Health implications of heart enlargement

Right atrial enlargement

This type of enlargement is seen when there is chronic pulmonary hypertension. It occurs when there is increased pressure in the pulmonary arteries, which results in the atria working harder to push blood into the ventricle.

Left atrial enlargement

Although a lot of factors can cause this type of enlargement, one of the primary causes is chronic hypertension. Blood flows from the left atrium into the left ventricle. When the blood pressure is persistently high for longer durations, the muscle of the left atrium has to use much force to push the blood into the ventricle. This results in the enlargement of the left atrium.

Heart failure

When your heart is unable to pump enough blood to the body, it is called heart failure. It may take years to reach this stage. Heart failure happens due to the thickening and stiffening of the heart muscles and the blood vessels due to chronic hypertension. When the blood vessels (arteries) become narrow and stiff, it obstructs the flow of blood to the body parts. To compensate for this inadequacy and to meet the demands of the body, the heart pumps harder, resulting in enlargement. Unfortunately, the larger the heart becomes, the harder it becomes for it to meet the body’s requirements.⁸

Management and prevention

Importance of early detection and treatment 

Many times, hypertension goes undiagnosed. It is important to periodically get your blood pressure monitored by your healthcare provider to catch any abnormality at an early stage and manage the condition accordingly.⁹

Lifestyle modifications

• Healthy dietary habits 
• Limiting salt intake
• Cessation of alcohol and smoking
• Hydration
• Improved physical activity
• Stress and anger management
• Getting enough quality sleep

Medical treatment

• Antihypertensive drugs
• Treatment of underlying risk factors like Diabetes and Hyperlipidemia
• Treatment of underlying conditions such as thyroid, sleep apnea, anaemia, arrhythmia, etc.

FAQs

How does chronic hypertension affect the heart?

Chronic Hypertension can affect the heart in many ways. It can lead to many serious conditions like heart failure, artery disease, arrhythmias, left ventricular hypertrophy, etc.

Can hypertension cause enlargement of the heart?

Yes, chronic hypertension can cause the heart muscles to enlarge. In chronic hypertension, the high blood pressure, the heart has to work harder to push blood into the blood vessels due to the higher resistance. 

What is the cause of an enlarged heart?

Common causes of an enlarged heart include:

• Chronic hypertension
• Coronary artery disease (CAD)
• Heart valve disease
• Congenital Heart disease
• Kidney disease 
• Anaemia
• Pregnancy

What to avoid when you have an enlarged heart?

• Salt
• Alcohol
• Caffeine
• Saturated fats
• Refined sugars
• Processed meat

Summary

Chronic hypertension or persistent high blood pressure causes the heart to work harder and push blood into the blood vessels against higher resistance. This leads to the thickening or stretching of the heart muscles. Although it acts as an adaptation in the beginning, over time, this leads to weakening of the heart muscles and eventually causes impaired heart functioning. As the heart enlarges, it becomes less efficient and increases the risk of heart failure. Chronic hypertension and heart enlargement (cardiomegaly) can be managed and reversed through lifestyle changes and medication. A healthy diet, adequate exercise and stress management can help individuals with chronic hypertension to lower their blood pressures and improve their quality of life.