There are many different conditions that can affect the heart. While certain conditions like coronary artery disease and a heart attack are well known, all of these conditions can eventually result in heart failure. There is a difference between heart failure involving the right side and the left side of the heart. It may also affect heart function in different ways which can eventually lead to a complete shutdown of the heart.
The Heart Structure
The heart is a muscular organ that is responsible for pumping blood through the vast network of blood vessels that distributes blood to tissues all over the body. The human heart is made up of four distinct chambers or compartments: two upper chambers and two lower chambers. The two upper chambers are technically referred to as the left atria and the right atria. The two lower chambers are technically referred to as the left ventricle and the right ventricle.
Each of these chambers is separated from the others through walls (technically referred to as septum). The upper atria are separated from the ventricles below by the atrioventricular septum. There is also a septum that separates the two ventricles (interventricular septum) and divides the heart into two separate halves. The left atrium and the left ventricle together constitute the left heart, whereas the right atrium and the right ventricle together constitute the right heart. This distinction between the left heart and right heart is both anatomical and physiological.
The upper atria are the heart chambers that receive blood into the heart, whereas the ventricles are the heart chambers that pump blood out of the heart. Central to the acts of receiving and pumping blood is the ability of the heart muscle to contract rhythmically. The electric currents that begin heart contractions are generated by a group of cells known as the pacemaker cells that are located in the walls of the right atrium. This location is known as the sinus node or the sinoatrial node (commonly abbreviated as the SA node).
The electrical impulse travels from the atrium to the ventricles through an electrical conduction system composed of the nerves of the heart. This leads to a rhythmic contraction of the heart in which the atria contract first, followed by the ventricles. This rhythmic and sequential contraction mechanism makes the blood flow through the various chambers of the heart possible.
Blood Flow Through The Heart
The right atrium receives deoxygenated blood from the tissues all over the body. This deoxygenated blood is channeled into the right atria through two major veins known as the superior vena cava and the inferior vena cava. The superior vena cava supplies deoxygenated blood from the body parts that lie above the diaphragm, whereas the inferior vena cava supplies deoxygenated blood from the body parts that lie below the diaphragm.
Deoxygenated blood from the heart muscle itself is drained into the right atrium through the coronary sinus. As the right atrium contracts, it passes the deoxygenated blood into the lower right ventricle through a unidirectional valve known as the tricuspid valve. Contraction of the right ventricle pushes blood out into the pulmonary arteries that carry the deoxygenated blood to the lungs for oxygenation. The right heart, therefore, acts to collect deoxygenated blood from all over the body and send it to the lungs for oxygenation.
The oxygenated blood from the lungs is received by the left atrium through the pulmonary veins. Contraction of the left atrium pushes this oxygenated blood into the left ventricle through the unidirectional bicuspid valve. Contraction of the left ventricle pushes the blood out of the heart into the aorta, which is a major artery. The blood from the aorta is then distributed through a vast network of arteries that supply blood to all the tissues of the body. The left heart, therefore, acts to receive oxygenated blood from the lungs and supply that blood to all the tissues of the body.
Heart failure refers to an inability of the heart to either receive or pump blood efficiently. Due to the failure of blood circulation and reduced cardiac output (the volume of blood pumped out by the heart), fluid starts accumulating in the tissues of the body, leading to swelling. Because of this fluid accumulation in various tissues of the body, heart failure is also commonly referred to as congestive heart failure. The decrease in cardiac output in heart failure could be due to the following reasons:
- The heart may not receive sufficient blood from the veins to fill up the ventricles, and produce sufficient pressure within the heart chambers.
- The blood vessels may lose their elasticity, which affects the flow of blood through them.
- The heart muscles may not be able to contract forcefully.
- Heart failure can also be classified into left heart failure versus right heart failure.
Left heart failure
Left heart failure is characterized by a reduction in the output of the left ventricle. For this reason, left heart failure is also referred to as left ventricular failure (abbreviated as LVF). As the left ventricles are not able to push out blood in an efficient manner, there is a backup of oxygenated blood leading to increased pressure in the left atrium.
Right heart failure
Right heart failure is characterized by a reduction in the output of the right ventricle. For this reason, right heart failure is also referred to as right ventricular failure (abbreviated as RVF). Unlike in left heart failure, however, the pressure in the right atrium may either be normal or abnormal, depending on the rate of return of the blood from the tissues of the body. Right heart failure is a less common condition than left heart failure. However, both conditions eventually cause an overall reduction in the cardiac output. When that happens, the condition is referred to as biventricular heart failure.
Signs and Symptoms
The common symptoms of heart failure include shortness of breath, rapid heartbeats, swelling in the legs, and fatigue. However, the signs and symptoms of heart failure are frequently categorized as being caused by left heart failure or right heart failure. This is because the left and right sides of the heart cater to blood circulation in different parts of the body. The following are some of the signs and symptoms that differ in left heart failure versus right heart failure:
- Pitting edema: Pitting edema refers to visible tissue swelling in which temporary depressions can be formed by applying pressure with a finger. Pitting edema of the hands and legs is a common sign of both left and right heart failures. However, the intensity of edema differs in the two conditions. Left heart failure causes only mild-to-moderate pitting edema, whereas right heart failure causes moderate-to-severe pitting edema.
- Retention of fluid: The areas of fluid retention differ in left heart failure and right heart failure. Pulmonary edema and pleural effusion are characteristic of left heart failure, whereas ascites is common in right heart failure.
- Organ enlargement: Heart is enlarged in left heart failure. Liver enlargement and jaundice may be seen in right heart failure.
- Distension of veins in the neck: Jugular venous pressure is raised only to a mild or moderate extent in left heart failure. However, jugular venous pressure is severely elevated in right heart failure, resulting in visibly distended veins in the neck.
- Shortness of breath: Paroxysmal nocturnal dyspnea is a prominent feature of left heart failure. However, dyspnea is not so prominent in right heart failure.
- Gastrointestinal problems: Gastrointestinal problems may be present in left heart failure. However, they are not very prominent. Right heart failure can result in prominent gastrointestinal problems such as bloating, constipation and loss of appetite.
Despite the above mentioned differences in signs and symptoms between left heart failure and right heart failure, it is difficult to distinguish between these two conditions based solely on these criteria. Individual variability in signs and symptoms may occur due to multiple underlying factors.