General Health

Heart Valves- Associated Diseases and Artificial Valves

Introduction

The heart valves keep the blood flowing in the right direction. The four main heart valves which are present in the heart are-

1)Tricuspid Heart Valve – The tricuspid heart valve has three valves or cusps. This heart valve separates the top right chamber (right atrium) from the bottom right chamber (right ventricle). The valve allows the transfer flow of blood from the right atrium to the right ventricles and prevents the backflow from the right ventricle to the right atrium. The diseases associated with these valves are

  • tricuspid atresia – tricuspid atresia is a heart defect present at birth (congenital) in which a valve (tricuspid valve) between two of the heart’s chambers isn’t formed
  • tricuspid regurgitation – tricuspid regurgitation, or tricuspid valve regurgitation, occurs when the valve’s flaps (cusps or leaflets) do not close properly. Blood can leak backward into the atrium from the leaky tricuspid valve, causing your heart to pump harder to move blood through the valve.
  • tricuspid stenosis – tricuspid valve stenosis, also known as tricuspid stenosis, is a narrowing in the heart’s tricuspid valve. The tricuspid valve sits between the right atrium (upper chamber of the heart) and right ventricle (lower chamber of the heart) and prevents blood flow from returning into the right atrium from the right ventricle.

2) Pulmonary Valve – The valve has three leaflets; the valve separates the right ventricle from the pulmonary artery. The valve opens to allow blood to be pumped from the right ventricle to the lungs (through the pulmonary artery) where it will receive oxygen and prevents the backflow of blood from the pulmonary artery to the right ventricle. The diseases associated with these valves are

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  • pulmonary valve stenosis – pulmonary valve stenosis is a narrowing of the valve located between the lower right heart chamber (right ventricle) and the lung arteries (pulmonary arteries). In a narrowed heart valve, the valve flaps (cusps) may become thick or stiff. This reduces blood flow through the valve.
  • pulmonary valve regurgitation – pulmonary valve regurgitation occurs when the pulmonary valve doesn’t completely close and allows some blood to leak back into the heart. This condition is also known as pulmonic regurgitation, pulmonic insufficiency, and pulmonary insufficiency. Pulmonary regurgitation can be categorized as mild, moderate, or severe.

3) Mitral Valve- The valve has two leaflets, and these valves are from the left atrium and left ventricles, and when these valves open it allows the blood flow from the left atrium to the left ventricles. The diseases associated with these heart valves are

  • mitral valve prolapse – Improper closure of the valve between the heart’s upper and lower-left chambers. Mitral valve prolapse can develop at any age. It can run in families and may be linked to other conditions, such as infection and connective tissue disease.
  • mitral valve regurgitation – it is a type of heart valve disease in which the valve between the left heart chambers doesn’t close completely, allowing blood to leak backward across the valve. It is the most common type of heart valve disease (valvular heart disease).
  • mitral valve stenosis – is a narrowing of the heart’s mitral valve. This abnormal valve doesn’t open properly, blocking blood flow into the main pumping chamber of your heart (left ventricle). Mitral valve stenosis can make you tired and short of breath, among other problems.

4) Aortic Valve – Has three leaflets, unless it’s abnormal from birth, i.e., bicuspid aortic valve, which separates the left ventricle from the aorta. Opens to allow blood to leave the heart from the left ventricle through the aorta and the body. It prevents the backflow of blood from the aorta to the left ventricle. The disease associated with these valves are-

  • aortic regurgitation – is a condition that occurs when your heart’s aortic valve doesn’t close tightly. As a result, some of the blood pumped out of your heart’s main pumping chamber (left ventricle) leaks backward.
  • aortic stenosis – occurs when the heart’s aortic valve narrows. The valve doesn’t open fully, which reduces or blocks blood flow from your heart into the main artery to your body (aorta) and the rest of your body. Your treatment depends on the severity of your condition.

Artificial Heart Valves

An artificial heart valve is a one-way valve implanted into a person’s heart to replace a heart valve that is not functioning properly (valvular heart disease). Artificial heart valves can be separated into three broad classes: mechanical heart valves, bioprosthetic tissue valves, and engineered tissue valves.

Types of Heart Valves-

1.      Mechanical Heart Valves – Mechanical valves come in three main types – caged ball, tilting disc, and bi-leaflet – with various modifications on these designs. Caged ball valves are no longer implanted. Bileaflet valves are the most common type of mechanical valve implanted in patients today.

2.      Bioprosthetic Heart Valves- Bioprosthetic valves are usually made from animal tissue (heterograft/xenograft) attached to a metal or polymer support. Bovine (cow) tissue is most used, but some are made from porcine (pig) tissue. The tissue is treated to prevent rejection and calcification.

3.      Tissue-engineered valves- these tissue-engineered valves involve seeding human cells onto a scaffold. The two main types of scaffolds are natural scaffolds, such as decellularized tissue, or scaffolds made from degradable polymers. The scaffold acts as an extracellular matrix, guiding tissue growth into the correct 3D structure of the heart valve. Some tissue-engineered heart valves have been tested in clinical trials, but none are commercially available.

The most common problems with artificial heart valves are various forms of degeneration, including gross billowing of leaflets, ischemic mitral valve pathology, and minor chordal lengthening. The repairing process of the artificial heart valve regurgitation and stenosis usually requires open-heart surgery, and a repair or partial replacement of regurgitant valves is usually preferred. Thus, designing optimal artificial heart valves with reduced thromboembolic potential and better clinical outcomes requires a thorough understanding of the valvular flow fields. Heart Valves are the choice for people in cases where their natural valves get damaged, and based on the cardiologists’ decision people should opt for them.

Author: 

Ritika Gupta

Ritika Gupta is an MPharm. graduate who is keen on spreading awareness about various unexplored medical fields through her writings.

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