Heart is a pumping station and it pumps oxygenated blood all over the body through aorta. Heart undergoes rhythmic contractions and dilations which constitute a cardiac cycle. During a systole the ventricles contract and pump the blood into pulmonary artery and aorta. While during a diastole the ventricles relax during which they receive blood from the vena cava and pulmonary vein. The blood is pumped from the left ventricle into aorta though the semi lunar valves. An abnormal condition in which blood falls back into the ventricle while the ventricle is dilating is called Aortic regurgitation. Thus, the retrograde flow of blood through the aortic valve during a cardiac diastole leads to a clinical condition called Aortic regurgitation. It primarily occurs due to the inability of the aortic valve check the backward flow of the blood. Any kind of impairment in the valvular apparatus like leaflets, annulus of aorta cannot check the ascending blood from falling back into the left ventricle.
Certain pathological conditions like Openings present in the heart are called valves because they open in one direction like trapdoors to let the blood pass through. When they close, the blood cannot flow backwards into the atria. Therefore the presence of valves ensures that the blood always flows in only one direction inside the heart. The aortic valve has 3 thin leaflets (i.e. cusps) which project from the wall of the proximal ascending aorta. Aortic regurgitation can occur due to several reasons which may be congenital relating with the origin and the structure of an organ or acquired. Anatomical abnormalities associated with the structure of valve or the ascending aorta which cannot stop the blood from falling back into the left ventricle are ventricular septal defect of the membrane, absence of 2 or 3 aortic valve leaflets or dysplasia of valve cusps without the fusion of commissures.
However, valvular insufficiency can also be acquired which means it not presence science birth but is acquired during the course of life. Various systemic diseases, like rheumatic fever, systemic lupus erythematosus, connective tissue syndromes like Marfan syndrome, Ehlers-Danlos syndrome, type IV, Turner syndrome, endocarditis, trauma, prolonged and uncontrolled hypertension, collagen vascular diseases, degenerative aortic valve diseases ,cystic medial necrosis , senile aortic ectasia, syphilitic aortitis, giant cell arteritis, Takayasu arteritis, ankylosing spondylitis, Whipple disease have also been associated with aortic regurgitation.
Statistics show that the percentage of individuals with aortic valve insufficiency caused by aortic root disease has remarkably gone up as compared with the percentage of those with valvular disease. Of late, it has been recorded that more than half of patients with aortic regurgitation have aortic valve insufficiency caused by aortic root disease.
Aortic regurgitation is manifested in form of sudden, severe shortness of breath, rapidly developing heart failure, and chest pain if myocardial perfusion pressure is decreased or an aortic dissection is present. In case of chronic AR patient may undergo a long-standing period, without symptoms, that may last for several years. In order to maintain large forward stroke volume a compensatory tachycardia may develop which results in a decreased diastolic filling period. Other symptoms associated with severe AR are forced heart beats resulting in palpitations occurring due to increased pulse pressure, Shortness of breath which may not become grave due to a compensatory tachychardia in the initial stages, perpetual chest pain, and a sudden cardiac death, though is of a rare occurrence.
Various measures can are adopted to check aortic regurgitation but in acute, sevre cases surgical intervention is indicated. Drugs like dobutamine which enhance the cardiac output and shorten diastole and sodium nitroprusside to reduce after load in hypertensive patients are administered to the patients.
Vasodilator therapy is beneficial in to reducing the after load in patients with systolic hypertension and lowering down the wall stress and optimizing LV function. This therapy is a long-term therapy and is recommended to chronic AR patients who cannot undergo a surgery.
Diuretics, nitrates, and digoxin are also sometimes used to help control symptoms in patients with AR though, this is not widely recommended. Patients with prosthetic material in their hearts (such as artificial valves or valves repaired with prosthetic material) or a cardiac transplantation should be made to undergo prophylactic antibiotic therapy prior to dental procedures. Beta-blocker therapy is not adopted with the patients with severe AR because heart rate reduction could prolong diastole, thus worsening AR. It has been suggested in a recent experimental study suggested that beta-blocker therapy is associated with a significant survival benefit in patients with severe AR thus, this brings hope that further research may allow the recommendation of the same in future.