By Rachael Zimlich, BSN, RN 

Updated on August 18, 2023

 Medically reviewed by Richard N. Fogoros, MD

Left- and right-sided heart failure both occur because heart muscles are weakened, and they can’t work as effectively as before. When this happens, tissues throughout the body are deprived of oxygen and other crucial nutrients.

However, these types of heart failure differ in how the condition affects the pumping ability of the heart. The right side of the heart collects oxygen-depleted blood from the body and brings it to the lungs to be filled with fresh oxygen. The left side of the heart receives oxygen-rich blood from the lungs and sends it out to the rest of the body.¹

This article discusses these differences, and why left- vs. right-sided heart failure symptoms reflect specific mechanisms in heart failure. It presents information about how treatment options differ, too.

Illustration by Jessica Olah for Verywell Health

What Is Heart Failure?

Heart failure occurs when a person's heart can't pump enough blood to the body. There are a number of possible causes, including certain medical conditions that can lead to heart failure. They include:²

• High blood pressure

• Diabetes

• High cholesterol 

• Coronary artery disease

• Severe lung disease

• Obesity

• Sleep apnea

• Hyperthyroidism

Lifestyle choices like smoking, diet, and exercise can contribute to the development of heart failure. When symptoms of heart failure emerge, they typically align with either the left-side or right-side patterns of the disease.

What Is Left-Sided Heart Failure?

Left-sided heart failure is the most common type of heart failure. According to data from the American Heart Association, in the United States alone, 6.7 million adults over age 20 were living with heart failure from to 2017 through 2020.³

When it happens, your heart has lost some of its ability to pump blood out to your body after it’s been re-oxygenated. Without oxygen, tissues and organs throughout your body don’t work as well or begin to lose their function.⁴

 Congestive Heart Failure: Left-Sided Systolic

As the left side of the heart loses its ability to push blood out of the heart, blood can back up. Since blood is carried by the pulmonary veins from the lungs to the left side of the heart, blood backing up from the left heart can produce lung congestion and tends to affect breathing.

 Congestive Heart Failure: Left-Sided Diastolic

Thus, left-sided heart failure can cause both respiratory symptoms and problems in the tissues or organs receiving the least amount of oxygen-rich blood.

Symptoms

Shortness of breath and fatigue are common, early symptoms of left-sided heart failure. Sudden weight gain or swelling, especially in your limbs, are usually early signs of right-sided heart failure.

The most common symptoms of left-sided heart failure include:⁴

• Shortness of breath

• Coughing

• Weakness, especially in the legs

• Kidney problems or increased nighttime urination

• Increased heart rate as the heart works harder to pump blood out

Left-sided heart failure is usually caused by coronary artery disease which can reduce blood flow to the heart muscle, heart attacks, or prolonged high blood pressure (hypertension).⁴

Left-sided heart failure is further classified as systolic or diastolic failure, according to the condition of the heart muscle.

Systolic Failure

Systolic failure, or heart failure with a reduced ejection fraction, happens when the left side of the heart becomes weakened and is unable to contract with enough force to eject a sufficient amount of blood out to the body.

What Is an Ejection Fraction?

An ejection fraction is a measurement, expressed as a percentage, of how much blood the left ventricle pumps out with each contraction.⁵ An ejection fraction of 60% means that 60% of the total amount of blood in the left ventricle is pushed out with each heartbeat. A normal ejection fraction is between 50% and 70%.

Organs like the kidneys require a certain amount of pressure as blood flows through them to work properly. A weak pump can reduce this pressure and in turn decrease the ability of other organs, like the kidneys, to do their jobs. This is how heart failure can lead to multiple organ failure and even death.⁴

Diastolic Failure

Diastolic heart failure is also known as heart failure with a preserved ejection fraction. In this type of heart failure, the left side of the heart has become stiff and doesn’t relax well between beats.

While the heart’s pumping ability remains strong, the walls of the heart, particularly in the left ventricle, don’t relax enough to fill the chamber with an adequate amount of blood. So while the blood is pushed out of the heart forcefully, not enough is pumped with each beat.⁴

 Systolic vs. Diastolic Heart Failure

What Is Right-Sided Heart Failure?

In right-sided heart failure, the heart loses some of its ability to move oxygen-depleted blood to the lungs to pick up new oxygen. Blood enters the right atrium from the body and flows to the right ventricle, which pumps the blood through the pulmonary artery to the lungs and the left side of the heart.

 Congestive Heart Failure: Right-Sided Systolic

Right-sided heart failure is most often caused by advanced left-sided heart failure. It also can occur due to high blood pressure in the lungs (pulmonary hypertension) or a pulmonary embolism (blockage from a blood clot).⁶

As the left side of the heart loses its ability to pump blood out to the body, blood backs up into the right side of the heart. The right side of the heart then has to work harder, compensating for the weakness in the left side.

This heavier workload can lead to right-sided heart failure. However, right-sided heart failure can also occur even when the left side of the heart is apparently normal.

 Congestive Heart Failure: Right-Sided Diastolic

Causes

The causes of right-sided heart failure can include:⁷

• Chronic lung diseases like chronic obstructive pulmonary disease (COPD)

• Coronary artery disease

• Malfunction of heart valves, especially the tricuspid and pulmonic valves

• A thickened or restrictive pericardium (the sac that surrounds the heart)

• Congenital heart defects

Right-sided heart failure usually follows left-sided heart failure, so it can be difficult to differentiate the symptoms of the two. However, right-sided heart failure is characterized by a buildup of fluid in the vessels leading to the heart. This can cause swelling, mostly in the legs, genital area, and abdomen.⁷

What if Both Sides of the Heart Fail?

In severe cases or advanced heart failure, both sides of the heart can be affected. This is referred to as biventricular heart failure.⁴

Heart Failure Treatment

Heart failure treatment depends primarily on what type of heart failure you have and the degree of damage that has already been done. The most important thing you can do to manage heart failure is to make lifestyle changes like:⁸

• Control other chronic conditions like hypertension and diabetes

• Eat a healthy diet

• Quit smoking

• Avoid alcohol and illicit drugs

• Exercise

• Lower your intake of fats and sodium

What Are the Stages of Heart Failure?

Each type of heart failure is classified into four stages: A, B, C, and D. The key to managing heart failure is to make changes and adhere to treatment strategies that stop or slow the progression of your heart failure from one level to the next.⁹

A number of medications may be used to increase the function of your heart. For right-sided heart failure, the following may be prescribed:¹⁰

• Medications for correcting problems that caused the heart failure, like hypertension

• Diuretics like furosemide to reduce fluid buildup and swelling

• Anticoagulants like warfarin to reduce clotting in stagnant blood that backs up in the right atrium

• Medications to increase the pumping ability or elasticity of the heart

• Implanted devices that help the heart pump more effectively

Left-sided heart failure requires slightly different treatments, including:¹⁰

• Diuretics to reduce swelling

• Medications to control high blood pressure

• Inotropic medications that can help your heart pump more effectively

• Medications that reduce the strain on the heart and help it pump better like digoxin

• Implanted devices or a pump to help supplement the work of the heart

As your heart failure progresses, you may need additional treatments to manage the complications of heart failure, including medications to help support your kidney function or lifestyle changes to cope with the fatigue and weakness that heart failure can cause.

 How to Be an Effective Caregiver for a Person With Heart Failure

Summary

Left- and right-sided heart failure both ultimately lead to insufficient oxygen and nutrients delivered to the body's organs and tissues, but the symptoms and treatment of each are slightly different.

If you experience shortness of breath, fatigue, sudden weight gain, and swelling in your limbs, contact your doctor right away because these are early signs of heart failure.