What is the difference between the left and right side of the heart?

The heart weighs between 200 and 425 grams and is a little larger than the size of your fist. It has a volume capacity of 80-100mls. By the end of a long life a person’s heart may have beat more than 3.5 billion times. In fact, each day the average heart beats about 100,000 times, pumping around 7500 litres of blood.

Your heart has 4 chambers. The upper chambers are called the left and right atria and the lower chambers are called the left and right ventricles. A wall of muscle called the septum separates the left and right atria and the left and right ventricles. These are referred to as the atrial and ventricular septum. You may have heard your doctor refer to a condition called a ‘hole in the heart’. This simply means a tiny hole in the atrial septum separating the atria (called a PFO– Patent Foramen ovale or ASD—Atrial Septal Defect) or in the ventricular septum separating the ventricles (called a VSD—Ventricular Septal Defect). The left ventricle is the largest and strongest chamber in your heart.

The left ventricle’s chamber walls are only about 1.0 to 1.3cm, but they have enough force to push blood through the aortic valve and into your body.

Four types of valve regulate blood flow through your heart:

1. The tricuspid valve regulates blood flow between the right atrium and right ventricle.
2. The pulmonary valve controls blood flow from the right ventricle into the pulmonary arteries, which carry blood to your lungs to pick up oxygen.
3. The mitral valve lets oxygen rich blood from your lungs pass from the left atrium into the left ventricle.
4. The aortic valve opens the way for oxygen rich blood to pass from the left ventricle into the aorta, your body’s largest artery, where it is delivered to the rest of your body.

A more detailed description of blood flow through the heart is seen below.

Blood enters the right atrium of the heart through the superior vena cava. The right atrium contracts and pushes the blood cells through the tricuspid valve into the right ventricle. The right ventricle then contracts and pushes the blood through the pulmonary valve into the pulmonary artery, which takes it to the lungs. In the lungs, the blood cells exchange carbon dioxide for oxygen. The oxygenated blood returns to the heart via the pulmonary veins and enters the left atrium. The left atrium contracts and pumps the blood through the mitral valve into the left ventricle. Finally, the left ventricle contracts and pushes the blood into the aorta. The aorta branches off into several different arteries that pump the oxygenated blood to various parts of the body.

Heart failure is a condition where the heart can’t pump enough blood to meet the body’s demands. The 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.

In the United States alone, more than six million adults have been diagnosed with heart failure.

Heart failure is usually divided into two categories based on which side of the heart it mainly affects. 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.

While the end result is the same, symptoms can vary based on whether the right or left side of the heart is affected.

Left-sided heart failure is the most common type of heart failure. 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.

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.

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.

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

• 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).

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

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.

An ejection fraction is a measurement, expressed as a percentage, of how much blood the left ventricle pumps out with each contraction. 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.

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.

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.

Right-sided heart failure is most often caused by left-sided heart failure. This is because, as blood backs up from the left side of the heart into the pulmonary artery, the right side of the heart has to work harder to move blood to the left side. However, right-sided heart failure can also occur even when the left side of the heart is apparently normal.

The causes of right-sided heart failure can include:

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.

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

Heart failure treatment depends a lot 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:

• 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

Each type of heart failure is classified into stages. There are four stages—A, B, C, and D—and once you progress from one stage to another, there is no going back. 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.

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

• 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:

• 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.

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.

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.

Left- and right-sided heart failure both ultimately lead to the organs and tissues in your body not receiving enough oxygen and nutrients, 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.