Biomechanics of Mechanical Heart Valve3729

December 2003 Applications of Engineering Mechanics in Medicine, GED at University of Puerto Rico, Mayagüez 1 BIOMECHANICS OF MECHANICAL HEART VALVE 1 Benjamín González, Humberto Benítez, Kenneth Rufino, Merisabeth Fernández and Waleska Echevarría 2 Abstract - Heart valves all are prone to disease and malfunction, and can be replaced by prosthetic heart valves. The two main types of prosthetic hear t valves are mechanical and bioprosthetic. The mechanical valve is excellent in terms of durability, but is hindered by its tendency to coagulate the b lood. Bioprosthetic valve i s less durable and must be replaced periodically. All valve types must be durable, because the body is an extremely hostile environment for a foreign object, including pros thetic heart valves. Today, engineers are researchi ng new designs of prosthetic heart valves. They use the mechanical properties to make an artificial heart valve design. An artificial mitral valve is an option for humans with irreparable valve disease. Key words -- Heart valve, Biocompatibility, Alumina, Titanium, Biomaterial, Polyether urethane, Polyester, Pyrolitic carbon. INTRODUCTION Heart valves prevent the backflow of blood, which ensures the proper direction of blood flow through the circulatory system. Without these valves, the heart would have to work much harder to push blood into adjacent chambers. The heart is composed of 4 valves (Figure 1). The Tricuspid valve is between the right atrium and right ventricle. The Pulmonary valve is between the right ventricle and the pulmonary artery. The Aortic valve is between ventricle and the aorta and the Mitral valve is between the left atrium and left ventricle. It opens and closes to control blood flowing into the left side of the heart. Heart valves open like a trapdoor. The leaflets of the mitral valve open when the left atrium contracts, forcing blood through the leaflets and into the left ventricle. When the left atrium relaxes between heart contractions, the flaps shut to prevent blood, that has just passed into the left ventricle, from flowing backward. 1 This review article was prepared on December 8, 2003 for the course on Mechanics of Materials - I. Course Instructor: Dr. Meg h R. Goyal. Professor in Biomedical Engineering, General Engineering Department, PO BOX 5984, Mayagüez Puerto Rico 00687-5984. For details contact: [email protected] or visit at: http://www.ece.uprm.edu/m~goyal/home.htm 2 The authors are in the alphabetical order. The mitral valve, which lies between the two left chambers of the heart, consists of two triangular-shaped flaps of tissue called leaflets. The leaflets of the mitral valve are connected to the heart muscle through a ring called the annulus, which acts like a hinge. The mitral valve is anchored to the left ventricle by tendonlike cords, resembling the strings of a parachute, called chordae tendineae cordis. When working properly, heart valves open and close fully. In mitral regurgitation, the mitral valve does not open or close properly. Some blood from the left ventricle flows backward into the left atrium with each heartbeat. Regurgitation refers to the leakage (backflow) of blood through a heart valve. Figure 1. Heart Valves [1]. Heart Valve Problems [7] There are numerous complications and diseases of the heart valves that can prevent the proper flow of blood. Heart valve diseases fall into two categories: Stenosis and Incompetence. The stenotic heart valve prevents the valve from opening fully, due to stiffened valve tissue. Hence, there is more work required to push blood through the valve. Whereas, the incompetent valves cause inefficient blood circulation and cause backflow of blood in the heart, called as regurgitation. Treatment Options [22] On a large scale, medication is the best alternative, but in some cases defective valves have to be replaced with a prosthetic valve in order for the patient to live a normal life. An enormous amount of research and development has proven to be most beneficial, as prosthetic heart valve technology has saved thousands of lives. Engineers and The best place to find helping hand is at the end of y our arm --- Swedish Proverb.

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