By: Sadwika Salain
Artificial Valves
1 Introduction
Anatomically, the human heart comprises of four chambers—two atria and two ventricles. (Detail of the heart components is shown on figure 1). Physiologically, the heart can be considered as a positive displacement pump that generates blood flow to support systemic and pulmonary circulation. For this purpose, the heart undergoes both contraction and expansion in alternating period. It is estimated that the heart contracts and expands as many as on average 100,000 times everyday, pumping approximately 2,000 gallons of blood (Bender, 1992).
To ensure the blood flows in a forward direction, two valves at each ventricle – one at the inlet – open and shut in a synchronized manner. The four heart valves are:
- Tricuspid valve : located between the right atrium and the right ventricle
- Pulmonary valve : located between the right ventricle and the pulmonary artery
- Mitral valve : between the left atrium and the left ventricle
- Aortic valve : between the left ventricle and the aorta
The blood come from the veins, which has less oxygen, enters the heart via the right atrium. After filling, the right atrium then contracts and pushes the blood to the right ventricle through the tricuspid valve. From this ventricle, blood is sent to the lung through the pulmonary valve. In the lung the blood is oxygenated. Furthermore, the oxygenated blood returns to the left atrium then goes to the left ventricle through the mitral valve. The final stage is, the blood is squeezed out from the left atrium into the aorta and other circulatory system through the aortic valve. Detail of how the heart valve is working will be described in the following section. (more…)
