Human heart consists of four chambers, two atria (upper chambers) and two ventricles (lower chambers). Flow across these vessels and great arteries is unidirectional and is directed along a particular course due to the presence of heart valves, through which blood passes before leaving each chamber of the heart. The valves prevent the backward flow of blood and ensure that under normal circumstances, flow is unidirectional. These valves are actually tissue flaps that are located on inflow and outflow of each of the two ventricles (lower chambers of the heart). Each valve has three tissueflaps which meet along the lines of coaptation, except the mitral valve, which has two flaps. The four heart valves traditionally present include:
Heart valves are structurally or functionally affected in a variety of disease states causing abnormal flow of blood across the chambers. This can cause a variety of symptoms either due to the lack of blood reaching the end organs or accumulation of blood in the tissues like lungs. The most common conditions affecting heart valves primarily in india are rheumatic heart disease, sclero-degenerative or age related degeneration disease, congenital, infective endocarditis, aortic aneurysm, aortic dissections, traumatic etc. Heart valve disease can also occur secondary to other cardiac conditions like ischemia or infarction, tumours, cardiomyopathies etc.
Heart valve disease can alter valve functionality by either causing leakage (regurgitation) or obstruction to flow (stenosis) or both. Regurgitation happens when one(or more)valve(s) does not close completely, becomes leaky and causes the blood to flow backward instead of forward through the valve. In valve stenosis, one (or more) valve(s) opening becomes narrowed, stiffed or does not open appropriately, inhibiting the flow of blood out of the chamber. The heart is then forced to pump blood with increased force in order to move blood through the stiff (stenotic) valve(s).Regurgitant lesions are usually well tolerated and present with symptoms at a later stage with an exception of acute regurgitation states. Patients with stenotic lesions are symptomatic at an earlier stage of disease progression and the extent of symptoms are also much worse.
Usual symptoms for any patient with valvular heart disease include breathlessness, chest pain or discomfort, exertional fatigue, syncope, palpitations and swelling over legs and feet. 2Dimension Echocardiography can easily diagnose and quantify the severity of all valvular heart diseases. Based onthe severity of symptoms and the overall condition of heart, thesurgeon may decide that the diseased valve(s) needs to be surgically repaired or replaced.
Both heart valve repair or replacement begin with the induction of general anaesthesia and access to heart is gained with midline incision and median sternotomy.Since heart valve surgery is an open-heart procedure, all of them are accomplished with the aid of the heart lung machine. During the process of valve repair or replacement the beating of the heart is stopped by the use of cardioplegia. Circulation of blood in the body and oxygenation of bloodis performed in the interim by the heart lung machine.Once the procedure is complete, the beating of the heart is restarted and after ensuring satisfactory valve function and contractilefunction of the heart, the heart lung machine is weaned off.
Performing a heart valve repair depends on the type of valve disease andis usually the preferred approach as it preserves the native heart valve and may also help in preserving heart function.Heart valve repair surgeriesmay be performed under following circumstances:
In conditions where heart valve repair is not feasible or is unlikely to produce beneficial results due to excessive calcification, thickening or damage to native leaflets secondary to advanced disease process, heart valve replacement is recommended. In this process, the surgeon removes the native heart valve (completely or partially) and replaces it with an artificial heart valve. Artificial or prosthetic heart valves can be mechanical or biological tissue valve.Both these valves have certain pros and cons, and are recommended by the surgeon depending on specific conditions like patientage or disease state.
Minimally invasive valve surgery techniques include video-assisted surgery, robotic-assisted surgery or surgeries performed with an endoscope. This technique can be used for both repair as well as replacement of the damaged heart valves. Benefits of minimally invasive treatment options may include:
Once the valve repair or replacement is completed, the position and function of valve are confirmed with the help of transesophageal echocardiography. The patient is shifted to ICU in the immediate post operativeperriod for further optimization of heart and lung function, control of blood pressure and monitoring of post operative complications like bleeding, renal dysfunction, stroke, gastrointestinal dysfunction. All measures are taken to ensure complete asepsis and prevent infection in the post operative period. After ensuring complete recovery and stability in the ICU over 24-48 hours, patient is usually shifted to room for further rehabilitation, strength building, physiotherapy, nutritional build up and return to normal physiological state.
