Heart, lungs, arterias and venas constitute the cardiovascular system of the human organic structure. Heart, has the most critical map in human organic structure which is pumping of blood through-out the organic structure. Heart diseases are of many types. One of them is, disease of bosom valves. Heart valve diseases are the major menace to human life. The engineering has increased quickly and provided us with solutions to handle these bosom valve diseases. But still the figure of deceases due to these valve diseases is high. Heart valve diseases do non demo obvious symptoms, doing it really hard to name, for illustration a individual was holding valve disease at the age of 12yrs but it was diagnosed at the age of 31yrs. Heart valve diseases can be due to arthritic febrility, due to infection in valve, calcification or it can be inborn. ( 1 ) ( Cardiology explained )
Structure and map
Heart valve allows the blood to flux through bosom in different phases or degrees. Pumping of blood is a uninterrupted procedure of gap and shutting of the bosom valves. Four cardiac Chamberss are present in bosom, the upper two being atria and lower two ventricles. These are once more sub-divided into left atrium, right atrium, left ventricle and right ventricle. The de-oxygenated blood flows into the bosom through superior veins cava and inferior vein cava and enters right atrium. Then from right atrium it flows through right ventricle through tricuspid valve, so into pneumonic arterias to lungs through pneumonic valve.The deoxygenated blood is oxygenated in lungs and it flows back into pneumonic venas into left atrium and so through mitral valve it enters left ventricle which pumps the blood to aorta through aortal valve which flows to all parts of the organic structure. Heart valves guarantee that they do non let the wired blood to flux back. ( cardiology, tortora ) .
Mitral valve and tricuspid valves have similar constructions with one difference tricuspid valves have three semi lunar molded cusps or cusps whereas mitral valve has merely two. These cusps are connected to chordae tendineae and papillose musculuss. The difference in blood force per unit area in atria and ventricle leads to the gap and shutting of the cusps. Any infection or harm to the cusps or chordae tendineae leads to backward flow or escape of blood into different chamber which consequences in serious bosom valve jobs. The other two valves are aortal valve and pneumonic valve. These valves have three cusps which are semilunar Moon shaped attached to a valve ring. The valves open when the force per unit area in ventricles is more than the force per unit area in arterias and flows into pneumonic bole and aorta. Blood flows back to the bosom due to relaxation of ventricles therefore make fulling the cusps and shuting the valves. ( tortora, cardiology ) .
AORTIC VALVE DISEASES:
The proper map of aortal valve happens when the cusps are opening decently during systole and shutting wholly during diastole. Aortal valve disease occurs when cusps or cusps of the valve are damaged due to calcification, fibrosis and bacterial infection. The chief aortal valve diseases are aortal stricture and aortal regurgitation.
Aortal stricture ( AS ) is the most common valve disease in Europe and is largely observed in center or old age patients. ( 4 ) . Calcification occurs due colony of Ca which narrows the aortal valve. Therefore, the entire sum of oxygenated blood does non flux through it making a backwards flow of blood ensuing in increased force per unit area in left ventricle. Severe calcification requires immediate surgery, otherwise calcification might shut the opening of the valve ensuing in complete valve failure ( Julian ) . Chan states that calcification might get down from lipid accretion ensuing in Ca sedimentation. Though it is a terrible job but still there is no account of happening of calcification. Damage to the cusps leads to fibrosis or inspissating of the cusp and causes arthritic aortal stricture. Bicuspid aortal valve ( two cusps alternatively of three ) , subvalvar and supravalvar aortal stricture are inborn. They arise due to familial defects such as hempen tissue in the outflow piece of land. These can take to left ventricle hypertrophy.
When there is big sum of back flow of blood in the left ventricle, increasing the force per unit area and ensuing in distension of the left ventricle due to sudden addition in flow of blood and improper operation of the aortal cusps is aortal regurgitation. Aortal regurgitation arises due to arthritic febrility, morbific endocarditis, syphilitic aortitis and consequences in harm of cusps or distension of aorta. While Julian provinces that arthritic febrility leads to the cusps thickener, shortening and may be commissural merger chan claims that it leads to valve neovascularization, redness, commissural merger and thickener. Lymphocytes cause infiltration of the valve, if neovascularization and redness is present and it leads to the harm in valve tissues. Damage in valve tissues consequences in disfunction of the valve. Infection in endocarditis affects the construction of the cusps, cusps deteriorate and there is leak in blood flow as the cusps do non shut or open decently.
MITRAL VALVE DISEASES:
Selzer provinces that early position of arthritic disease was that it occurs in left side cardiac valves, which is non true in present conditions. Mitral valve diseases are the lone valve diseases happening chiefly due to arthritic febrility. Mitral valve cusps are connected to papillose musculuss and chordae tendineae any harm to these will do mitral valve disease. Mitral stricture and mitral regurgitation are the two chief mitral valve diseases.
Mitral stricture starts with acute carditis and arthritic carditis which amendss bosom musculuss and cusps of mitral valve, but this does non make narrowing of mitral valve. Mitral stricture can non be detected easy in its early phases, selzer concludes that in most of the patients mitral stricture to the full develops in a decennary. The pathology of mitral stricture is impairment of the cusps in commissures, due to this the cusps does non shut decently. As stated by Julian shortening of the chordae tendineae besides consequences in improper shutting of the cusps. The blood force per unit area in mitral valve is usually low but there is addition in the force per unit area due to decrease in the opening size ensuing in terrible haemodynamic effects. Comparing Julian and sezler, Julian provinces that normal size of valve opening is about 5cm? and it becomes chronic when valve size reduces to 1cm? or less while sezler provinces that normal size of valve opening is about 3cm? and as it reduces to 0.9cm? , it is terrible stricture and the patient has to undergo surgery. Pressure develops in the left atrium in chronic mitral stricture and the cardiac blood flow additions quickly and affects pneumonic venas and capillaries. Atrial fibrillation, pneumonic intercalation and respiratory jobs are developed due to mitral stricture.
Mitral regurgitation is back flow of blood in mitral valve. It is effect of many diseases impacting the valve such as arthritic endocarditis, calcification, distension of mitral valve, mitral valve prolapsus, papillose musculus malfunction. The shortening of chordae tendineae and harm in cusp consequences in alteration of the valve opening construction ( Julian ) . Mitral valve prolapsus ( MVP ) occurs when the mitral cusp is thickened due to damage of the different beds of the cusp ensuing in balloon like form of the cusp. It can be inborn or a developed disease. Schoen states that the present account for improper working of the cusps is perchance due to familial upset which weakens the valvular tissue.
In 1960 ‘s prosthetic bosom valves were introduced for the replacing of damaged bosom valves. Prosthetic bosom valves have surely decreased the rate of deceases due to failure of bosom valves but the life of prosthetic valve depends on many factors like type of valve, badness of disease in the patient and age of the patient. They can be divided chiefly into two sort of mechanical valves and biologic valves, these can be subdivided into many types. Ball -cage valves, leaning disc valves and bileaflet valves are the types of mechanical valves. Biologic valves can be sub-divided into allograft valves, autoplasty valve and bio-prosthetic valves. The inquiry of choice of better prosthetic valve still remains unreciprocated.
Mechanical valve and biologic valves
Ball coop valve ( Starr-Edwards ) was the first valve to be introduced in 1960. It has a ring molded base which was mounted by an alloy coop with a bio-compatible ball in it. It had reduced thrombosis but had other drawbacks such as bulky design and haemolysis ( p1 ) , to get the better of this leaning phonograph record valves were introduced. Leaning disc valves have a phonograph record attached to the base ring, it opens at a specific angle and so closes back as level phonograph record. Many alterations were made to the original tilting phonograph record valve i.e. Bjork-shiley valve, to better opening angle and to cut down thrombosis. But it showed defects, such as break in the metal prance. An improved version was introduced, Medtronic valve with Ti shell and C coated phonograph record which showed less thrombosis and produced automatically good consequences. Some of these valves are still in usage but the first bileaflet valve, St. Jude medical valve is used more than any other valve. It is made of pyrolytic C and wolfram, with two semi-circular cusps attached to a flexible joint system. It shows less thrombosis and better operation than other valves.Much more progresss were made in bileaflet valves and the current valve is Medtronic advantage valve, it has some design alterations and is suited for supra-annular nidation.
Biologic valves can be chiefly divided into bio-prosthetic valves, allografts and autoplasties. Bio-prosthetic valve consists of porcine and bovine valve stuff attached to prosthetic base. Porcine valves are preferred more than bovid valves. Stented porcine valves have porcine valve stuff sewed on stent for illustration, hancock bio-prosthesis valves which does non demo any structural harm and provides better hemodynamics. Mosaic bio-prosthetic valves abide anti-calcification intervention. Homograft valves are the valves that are stored from unsuccessful bosom grafts, pneumonic and aortal valves are normally used as allografts. Autografts are replacing of pneumonic valve of the patient from its place and puting it in the damaged valve place of the same patient and engrafting bio-prosthetic valve in pneumonic valve place.
The choice of valve for replacing is ever a subject of argument. With the engineering promotion and research, solutions for valve replacing has been found but still has its ain drawbacks and leaves the patient in quandary to make up one’s mind the type of valve to be implanted.
Mechanical valves have life-long structural lastingness and freedom from reoperation but leads to life-long job of anti-coagulation whereas bio-prosthetic valve does non demo any thrombosis so anti-coagulation is non required. But bio-prosthetic valve deteriorates and is non lasting, patients have to replace the bio-prosthetic valve in every 10-15 old ages. Age of patient dramas an of import function in choice of valve, younger patients can hold bio-prosthetic replacing as re-operation might non be complicated unless they have other jobs related to bosom as on the other manus older patients can hold mechanical replacing as due to their age it is non suggested to hold re-operation. The above standards can be considered but it is non possible wholly, it is non true for all the patients. Some younger patients might hold multiple valve jobs and re-operation might non be the right option for them.
Hemolysis might originate as a job in mechanical valves which is non a job in bio-prosthetic valve. Mechanical valves show bleeding complications and has life-long hazard of endocarditis. The Bjork-shiley mechanical valves have defect of break in the metal prances, so the lastingness depends on the type of mechanical valve used. Ball coop valve have bulky design therefore are non recommended for surgery affecting little pits. Homografts are natural signifier of valves but the success rate is really less. Patient ‘s organic structure might reject the valve, patient has high hazard of acquiring some viral infection from the giver. As these valves are preserved, saving and improper sterilisation methods can besides be a factor taking to failure of the valve. The advantage it has is hemodynamics of the valve is good.
Ross process is performed for nidation of autoplasties. As the pneumonic valve has similarities in construction with aortal valve, Ross process is performed on faulty aortal valve. This process is hazardous but has showed good consequences on immature patients.
After holding enormous options for valve replacing, till now no such valve has been developed which provides less or no complications. The factors to be considered are excessively many and each patient is non the same, so the success rate is different in different patients. It might depend on the life style and attention taken after surgery. The suggestion is that, as age plays a critical function in choice of valve so sing age a specific valve should be introduced for certain age group. The best manner would be to happen a better solution for thrombosis in mechanical valves.