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Aortic valve regurgitation

Introduction

Aortic regurgitation is the regurgitation (back flow) of blood to the left ventricle of the heart during diastole (relaxation) due aortic valve weakness.

As the left ventricle relaxes to fill with blood from the left atrium, blood leaks backward from the aorta, increasing the volume and pressure of blood in the left ventricle. As a result, the amount of work the heart has to do increases. To compensate, the muscular walls of the ventricles hypertrophy, and the chambers of the ventricles dilate. Eventually, despite this compensation, the heart may be unable to meet the body's need for blood, leading to heart failure.

Epidemiology

Incidence

Aortic insufficiency affects approximately 5 out of every 10,000 people.

Gender

Age

It is most common in men between the ages of 30 and 60. However, women and those older or younger can be affected too.

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Causes and risk factors

Rheumatic fever and syphilis used to be the most common causes of aortic regurgitation in North America, Australasia, and Western Europe, where both disorders are now rare because of the widespread use of antibiotics. In regions in which antibiotics are not widely used, aortic regurgitation due to rheumatic fever or syphilis is still common.

Aside from these infections, the most common causes of severe aortic regurgitation are weakening of the valve's usually tough, fibrous tissue due to myxomatous degeneration (a hereditary disorder in which the valve gradually becomes floppy); degeneration of the valve due to unknown factors; aortic aneurysms; and aortic dissection.

Common causes of mild aortic regurgitation are severe high blood pressure and a birth defect in which the aortic valve consists of two cusps (bicuspid valve) instead of the usual three (tricuspid valve). About 2% of boys and 1% of girls are born with this defect. Other causes of aortic regurgitation include bacterial infection of a heart valve (infective endocarditis) and injury.

Basically, any condition that damages a valve can cause or predispose regurgitation. Some of the more common ones include:

• Ankylosing spondylitis, a spinal disorder
• Aortic dissection and aortic aneurysm
• Congenital heart defects that are present at birth, such as unicuspid or bicuspid aortic valve
• High blood pressure
• Infective endocarditis, an infection in the valves or lining of the heart
• Marfan syndrome, an inherited disease of connective tissues
• Reiter syndrome, an arthritic disorder that affects adult males, which is now rare
• Rheumatic fever, a disease that can cause arthritis and heart problems
• Rheumatoid arthritis, which also causes joint pain and swelling
• Syphilis, especially congenital syphilis
• Systemic lupus erythematosus, an autoimmune disorder in which the person creates antibodies against his or her own tissues
• Ehlers - Danlos syndrome
• Pseudoxanthoma elasticum
• Deterioration of the valve with age

Pathogenesis

The ventricles pump blood in a forward direction from the heart to the aorta. Normally the aortic valve prevents backflow of blood to the heart when the heart relaxes after pumping. Back flow of the blood to the ventricle during relaxation leads to a subsequent increase in left ventricular volume. This leads to an increase in systolic blood pressure which is accompanied by reflex peripheral vessel dilatation which lowers the diastolic blood pressure resulting in a wide pulse pressure. The lowering of the diastolic blood pressure reduces flow of blood to the coronaries which relies on diastolic pressure. The resultant volume overload eventually leads to heart failure.

A leak may develop gradually (over months or years) or quickly (over hours or days). Aortic regurgitation may result when the aorta enlarges, often because of high blood pressure. When the aorta is enlarged, the valve may not close completely. As a result, blood leaks backward through the valve into the heart.

Aortic regurgitation may worsen if a person has a heart infection or aortic dissection. The function of the left heart chamber may deteriorate quickly within a few weeks or months. Chronic regurgitation usually progresses slowly. It can cause severe congestive heart failure, or CHF.

Clinical picture

Most often aortic valve regurgitation develops gradually, and the heart compensates for the problem. Aortic regurgitation usually progresses slowly over years. Mild aortic regurgitation produces no symptoms other than a characteristic heart murmur on auscultation. Many people do well despite moderate to severe regurgitation of the aortic valve. However, as aortic valve regurgitation progresses, signs and symptoms usually appear and may include:

Symptoms

• Fatigue and weakness, especially when the activity level is increased
• Shortness of breath, especially with exertion or when lying flat
• Bloody cough
• Angina pectoris – about 5% chest pain, discomfort or tightness, often increasing during exercise
• Fainting
• Rapid or irregular pulse
• Palpitations
• Edema that shows as swollen ankles and feet

Signs

The physical examination of an individual with aortic insufficiency involves auscultation of the heart to listen for the murmur of aortic insufficiency and related heart sounds. The murmur of chronic aortic insufficiency is a holodiastolic (lasts all of diastole) decrescendo murmur (starts off loud and becomes soft). The murmur of chronic aortic insufficiency has the following characteristics:

• Systolic ejection click
• Ejection murmur
• S3 present
• Holodiastolic decrescendo murmur - best heard with patient sitting and leaning forward (If radiation to the right parasternal region, consider ascending aortic aneurysm)
• Austin flint murmur (an apical diastolic rumble due to mitral regurgitation)

Physical signs of aortic insufficiency are related to the wide pulse pressure and the rapid decrease in blood pressure during diastole due to the AI:

• Lighthouse sign (blanching & flushing of forehead)
• de Musset's sign (head nodding in time with the heart beat)
• Ladolfi's sign (alternating constriction & dilatation of pupil)
• Becker's sign (pulsations of retinal vessels)
• Müller's sign (pulsations of uvula)
• Corrigan's pulse (rapid upstroke and collapse of the carotid artery pulse)
• (Watson's) Water-hammer pulse
• Quincke's sign (pulsation of the capillary bed in the nail)
• Mayen's sign (diastolic drop of BP>15 mm Hg with arm raised)
• Rosenbach's sign (pulsatile liver)
• Gerhardt's sign (enlarged spleen)
• Duroziez's sign (systolic and diastolic murmurs heard over the femoral artery when it is gradually compressed)
• Hill's sign (A ≥ 20 mmHg difference in popliteal and brachial systolic cuff pressures, seen in chronic severe AI)
• Traube's sign (a double sound heard over the femoral artery when it is compressed distally)
• Lincoln sign (pulsatile popliteal)
• Sherman sign (dorsalis pedis pulse is quickly located & unexpectedly prominent in age>75 yr)
• Key-Hodgkin murmur of AI is a harsh, raspy murmur caused by leaflet eventration that occurs in luetic aortopathy

Diagnosis

The initial diagnosis may be based on the clinical history, auscultation of the heart, abnormalities in the pulse, and the results of a chest x-ray. Other heart problems can cause signs and symptoms similar to those of aortic valve regurgitation, and it's possible to have more than one disorder at the same time. Common tests used for diagnosis of aortic valve regurgitation include:

• Doppler echocardiogram may be used to measure the volume of blood flowing backward through an aortic valve. This volume is expressed in cubic centimeters per beat.
• Chest X-ray. X-ray of the chest shows an enlargement of the left ventricle.
• Electrocardiogram (ECG) may show signs of an enlarged left ventricle.
• Transesophageal echocardiogram allows more closer look at the aortic valve and a clear picture of the amount of blood flowing through it.
• Exercise tests: Different types of exercise tests help measure tolerance for activity and heart's response to exertion (exercise).
• Cardiac catheterization can specifically show the blood leaking back from the aorta into the left ventricle. Some catheters used in cardiac catheterization have sensor devices (sensors) at the tips that can measure pressure within heart chambers, such as the left ventricle. Pressure may be increased in the left ventricle with aortic valve regurgitation.
• Coronary angiography is performed before surgery because about 20% of people with aortic regurgitation also have coronary artery disease.

Prevention and Self-care

Aortic valve regurgitation can also be prevented from high blood pressure by keeping blood pressure under control. High blood pressure can also cause the aorta to stretch out, which pulls the aortic valve leaflets apart and leads to regurgitation.

• Control of high blood pressure.
• Consuming less salt.
• Regular dental care.
• Maintaining a healthy weight.
• Exercise.
• Regular cardiology check up.

Some cases of aortic insufficiency can be prevented by treating underlying disorders. For example, effective treatment of autoimmune disorders may prevent some damage to the aortic valve. High blood pressure can be managed with lifestyle changes and medicines. Following safer sex guidelines can prevents some STDs.

Chronic aortic incompetence

1. Vasodilators

Heart failure due to aortic regurgitation can initially be treated with drugs. Unless aortic regurgitation is mild, surgery is ultimately almost always required. In the weeks before surgery, heart failure is treated with digoxin, diuretics, and a drug that dilates blood vessels and thus reduces the work of the heart, such as a calcium blocker (e.g. nifedipine), an angiotensin-converting enzyme (ACE) inhibitor, or hydralazine, plus a nitrate. An angiotensin II receptor blocker may be used when an ACE inhibitor cannot be used. Vasodilator therapy may delay the progression to valve replacement. Use of a pacemaker to increase the heart rate can sometimes help reduce the severity of heart failure.

2. Valve replacement

In chronic aortic regurgitation, surgery is indicated if the patient has symptoms. The damaged valve should be surgically replaced with an artificial valve before the left ventricle becomes irreversibly damaged and heart failure becomes too severe. Usually, echocardiography is performed periodically to determine how rapidly the left ventricle is enlarging, so that surgery can be scheduled at an appropriate time. Ventricular cavity enlargement more than 55 mm is an indication for surgical intervention. People with aortic regurgitation, even when mild, are at increased risk for developing an infection of the valve (endocarditis). They need to take antibiotics before certain dental or surgical procedures.

Acute aortic incompetence

1. Valve replacement

If regurgitation occurs quickly, the aortic valve is usually replaced as soon as possible.

2. Valve repair

If the cause of AI is endocarditis or aortic dissection, the valve may in some cases be repaired instead.

Prognosis and survival

Without treatment, aortic regurgitation tends to worsen over time. The outlook is worse for older people, partly because many of them also have coronary artery disease. If heart failure develops, the outlook is also worse. After heart valve replacement, people over 75 tend to continue to have heart problems (including heart failure) and are more likely to die.

If a person does not have symptoms and the left heart chamber works well, he or she may remain on medicine for a long time. Successful replacement of the valve restores normal blood flow. The long-term outcome is usually very good. Artificial valves wear out over a period of years. Their function is monitored, and the valves are replaced as necessary. Some artificial valves require that the person take antibiotics before and after surgeries or dental work to avoid serious heart infections, and anti-coagulants to avoid blood clots, such as deep venous thrombosis.

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