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Aortic regurgitation (AR), also known as aortic insufficiency (AI), is the leaking of the aortic valve of the heart that causes blood to flow in the reverse direction during ventricular diastole, from the aorta into the left ventricle. As a consequence, the cardiac muscle is forced to work harder than normal. Signs and symptoms Symptoms of aortic regurgitation are similar to those of heart failure and include the following: Dyspnea on exertion Orthopnea Paroxysmal nocturnal dyspnea Palpitations Angina pectoris Cyanosis (in acute cases) Causes In terms of the cause of aortic regurgitation, is often due to the aortic root dilation (annuloaortic ectasia), which is idiopathic in over 80% of cases, but otherwise may result from aging, syphilitic aortitis, osteogenesis imperfecta, aortic dissection, Behçet's disease, reactive arthritis and systemic hypertension. Aortic root dilation is the most common cause of aortic regurgitation in developed countries. Additionally, aortic regurgitation has been linked to the use of some medications, specifically medications containing fenfluramine or dexfenfluramine isomers and dopamine agonists. Other potential causes that affect the valve directly include Marfan syndrome, Ehlers–Danlos syndrome, ankylosing spondylitis, and systemic lupus erythematosus. In acute cases of aortic regurgitation, the main causes are infective endocarditis, aortic dissection or trauma. Pathophysiology The mechanism of aortic regurgitation, comprises the pressure in the left ventricle falling below the pressure in the aorta, the aortic valve is not able to completely close. This causes a leaking of blood from the aorta into the left ventricle. This means that some of the blood that was already ejected from the heart is regurgitating back into the heart. The percentage of blood that regurgitates back through the aortic valve due to AR is known as the regurgitant fraction. This regurgitant flow causes a decrease in the diastolic blood pressure in the aorta, and therefore an increase in the pulse pressure. Since some of the blood that is ejected during systole regurgitates back into the left ventricle during diastole, there is decreased effective forward flow in AR. While diastolic blood pressure is diminished and the pulse pressure widens, systolic blood pressure generally remains normal or can even be slightly elevated, this is because sympathetic nervous system and the renin-angiotensin-aldosterone axis of the kidneys compensate for the decreased cardiac output. Catecholamines will increase the heart rate and increase the strength of ventricular contraction, directly increasing cardiac output. Catecholamines will also cause peripheral vasoconstriction, which causes increased systemic vascular resistance and ensures that organs are adequately perfused. Renin, a proteolytic enzyme, cleaves angiotensinogen to angiotensin I, which is converted to angiotensin II. In the case of chronic aortic with resultant cardiac remodeling, heart failure will develop, and it is possible to see systolic pressures diminish. Aortic regurgitation causes both volume overload (elevated preload) and pressure overload (elevated afterload) of the heart. The volume overload, due to elevated pulse pressure and the systemic effects of neuroendocrine hormones causes left ventricular hypertrophy (LVH). There is both concentric hypertrophy and eccentric hypertrophy in AI. The concentric hypertrophy is due to the increased left ventricular pressure overload associated with AI, while the eccentric hypertrophy is due to volume overload caused by the regurgitant fraction. Physiologically, in individuals with a normally functioning aortic valve, the valve is only open when the pressure in the left ventricle is higher than the pressure in the aorta. This allows the blood to be ejected from the left ventricle into the aorta during ventricular systole. The amount of blood that is ejected by the heart is known as the stroke volume. Under normal conditions, >50% of the blood in a filled left ventricle is ejected into the aorta to be used by the body. After ventricular systole, the pressure in the left ventricle decreases as it relaxes and begins to fill up with blood from the left atrium. This relaxation of the left ventricle (early ventricular diastole) causes a fall in its pressure. When the pressure in the left ventricle falls below the pressure in the aorta, the aortic valve will close, preventing blood in the aorta from going back into the left ventricle. Diagnosis In terms of the diagnosis of aortic regurgitation a common test for the evaluation of the severity is transthoracic echocardiography, which can provide two-dimensional views of the regurgitant jet, allow measurement of velocity, and estimate jet volume. The findings in severe aortic regurgitation, based on the 2012 American College of Cardiology/American Heart Association guidelines include: Chest X-ray can assist in making the diagnosis, showing left ventricular hypertrophy and dilated aorta. ECG typically indicates left ventricular hypertrophy. Cardiac chamber catheterization assists in assessing the severity of regurgitation and any left ventricular dysfunction. Physical examination The physical examination of an individual with aortic regurgitation involves auscultation of the heart to listen for the murmur of aortic regurgitation and the S3 heart sound (S3 gallop correlates with development of LV dysfunction). The murmur of chronic aortic regurgitation is typically described as early diastolic and decrescendo, which is best heard in the third left intercostal space and may radiate along the left sternal border. If there is increased stroke volume of the left ventricle due to volume overload, an ejection systolic 'flow' murmur may also be present when auscultating the same aortic area. Unless there is concomitant aortic valve stenosis, the murmur should not start with an ejection click. There may also be an Austin Flint murmur, a soft mid-diastolic rumble heard at the apical area; it appears when a regurgitant jet of blood from severe aortic regurgitation partially closes the anterior mitral leaflet. Peripheral physical signs of aortic regurgitation are related to the high pulse pressure and the rapid decrease in blood pressure during diastole due to blood returning to the heart from the aorta through the incompetent aortic valve, although the usefulness of some of the eponymous signs has been questioned: Phonocardiograms detect AI by having electric voltage mimic the sounds the heart makes. Characteristics- indicative of aortic regurgitation are as follow: Classification The hemodynamic sequelae of AI are dependent on the rate of onset of AI. Therefore, can be acute or chronic as follows: Acute aortic regurgitation In acute AR, as may be seen with acute perforation of the aortic valve due to endocarditis, there will be a sudden increase in the volume of blood in the left ventricle.... Discover the Nahush A Mokadam Md popular books. Find the top 100 most popular Nahush A Mokadam Md books.