The aortic valve is composed of 3 thin cusps that project from the wall at the origin of the aorta.

These leaflets and their respective sinuses of Valsalva are called left, right, and non-coronary. They should allow unimpeded flow from the left ventricle to the aorta during systole and close swiftly and firmly to prevent backflow during diastole. Disease may impair outflow, permit backflow or a combination of both.

• Aortic stenosis (AS) refers to a tight valve. Aortic sclerosis is usually considered to be the precursor of calcified, degenerative AS but sclerosis is rather more common than stenosis.
• A leaking aortic valve is variously called insufficiency, incompetence and regurgitation. It may be argued that a stenotic valve is also insufficient or incompetent and so regurgitation is preferred.

Epidemiology

Aetiology

Aortic valve disease may be congenital or acquired. It may be part of a more complex syndrome such as Fallot's tetralogy. Post-rheumatic valve disease is becoming rarer and degenerative disease is more prominent in an aging population.

Prevalence

• Aortic valve disease occurs in 4 of every 1,000 births.
• There is a male preponderance of 3:1 in pure aortic stenosis or aortic regurgitation (AR) but, if there is also mitral valve disease, there is a female preponderance.
• Over age 65, 2 to 7% of people have some degree of AS.¹

Risk factors

• A congenital bicuspid or even unicuspid valve predisposes to both stenosis and regurgitation.
• AR can occur in systemic lupus erythematosis. It may also occur in Marfan's syndrome, Ehlers-Danlos syndrome type IV and Turner's syndrome. AR as a result of advanced syphilis with aortic aneurysm is rarely seen nowadays.
• Aortic dilatation causing AR can also occur with ankylosing spondylitis and Reiter's disease, and after Takayasu's disease.
• It may also occur with Behçet's syndrome.

Presentation

Symptoms

Symptoms will depend upon the severity of disease. Infants with severe disease present in the first few weeks of life with heart failure. They often have other abnormalities too. Older patients may give a history of rheumatic fever or Sydenham's chorea, although about 50% of classical rheumatic heart disease has no such history, and such a history is not invariably followed by heart disease. There may be a history of other conditions such as Marfan's syndrome. Symptoms are more likely if it is part of a complex.

Even with a quite marked pressure gradient across the valve, patients may be asymptomatic for many years but they may still be susceptible to sudden events. However, only 4% of sudden cardiac deaths in severe AS occur in asymptomatic patients.

Both stenosis and regurgitation, if significant, may cause shortness of breath on exertion. AS predisposes to angina and is a reason to auscultate the chest when a patient presents with angina. It can also cause syncope on exertion and even sudden death and so violent exertion should be avoided. Pure AR can also cause angina but less often than pure AS.

AS tends to cause more problems than regurgitation. Symptoms of congenital disease often appear between age 10 and 20 years old. The classic triad of chest pain, heart failure and syncope are found in only 30 to 40% and usually after age 50 years old. Fatigue may be the presentation in children. Syncope, especially on exertion, may be from arrhythmia or sudden heart failure with an abrupt decline in cardiac output.

Signs

Techniques of examination are described elsewhere and will not be repeated here. Separate articles include History and Physical Examination, Examining the Pulse (Different Types) and Jugular Venous Pressure. Remember to look and feel before auscultation. Murmurs and heart sounds in children is a complex topic - see separate article Heart Murmurs in Children.

• Disease of the aortic valve affects the character of the arterial pulse. Examination of the pulse in significant AS reveals a slow-rising, flat character called pulsus parvus et tardus. Blood pressure will show a narrow pulse pressure (difference between systolic and diastolic pressures). In the elderly, a rigid aorta may make this sign less obvious.
• In AR, the pulse pressure will be wide with a sudden collapse of the pulse at the end. The classical Corrigan or "water-hammer pulse" is rarely felt these days as such marked disease is surgically corrected. For similar reasons, signs associated with very high pulse pressure such as the head bobbing with each pulse and pulsus bisferiens are largely of historical interest.
• Examination of the cardiovascular system includes palpation of the cardiac apex. There may be a thrill. In regurgitation the left ventricle is enlarged as each beat has to pump the required cardiac output plus that which regurgitates. In AS the left ventricle hypertrophies as more force is required to eject the blood past a tight valve. In laminar flow, the resistance to flow is proportional to the 4th power of the radius so that a small reduction in calibre has a marked effect on resistance.
• An abnormal aortic valve can become the site of subacute bacterial endocarditis. Clubbing of fingers takes about 6 weeks to develop. Splinter haemorrhages appear earlier.

For detail on auscultation of the heart, see separate article Heart Auscultation. Heart sounds (whether normal or pathological) are caused by turbulent blood flow; laminar flow is silent. Auscultation of the heart involves listening to the heart sounds as well as any murmurs. The loudness of a murmur is not a good index of the severity of disease. Ejection sounds are more obvious in children in whom the valves are more mobile than in older people. If congestive heart failure leads to a fall in cardiac output, the murmur will be quieter.

• Aortic stenosis
  • A2 is soft in AS. In aortic sclerosis A2 is normal or loud.
  • Both conditions are associated with an early, harsh systolic murmur that is transmitted to the carotids. A similar murmur may occur without stenosis if turbulence is due to aortic aneurysm causing dilation of the proximal aorta. Such pathology may cause leakage from the valve too and with it an early diastolic murmur.
  • The typical murmur of AS is a crescendo-decrescendo systolic ejection murmur shortly after the first heart sound that ends just before the second heart sound. It is a rough, low-pitched sound that is loudest at the base of the heart and most commonly heard in the second right intercostal space. An ejection click may be present, especially with bicuspid valves.
  • A fourth heart sound indicates left ventricular hypertrophy (LVH) in severe AS. If the left ventricle dilates and fails, a third heart sound may be heard.
• Aortic regurgitation
  • S1 is soft and there is an early diastolic murmur, best heard in the aortic area, with the patient sitting forward and in expiration. Both the murmur of regurgitation and the flow murmur from aortic dilatation are not well transmitted to the carotids. If significant regurgitation means that the stroke volume is very high, there will be an ejection flow murmur too.
  • In subacute bacterial endocarditis, the only feature may be a change in nature of the murmur.
  • Rarely, the aortic valve may collapse and become completely incompetent, producing the sound of "a cooing dove". This requires urgent valve replacement.

Differential diagnosis

There are a number of pathologies that can produce murmurs that are, or appear to be, from the aortic valve:

• Aortic stenosis
• Aortic sclerosis
• Aortic regurgitation
• Subacute bacterial endocarditis
• Dilatation of the root of the aorta (may also lead to a leaking valve)
• Flow murmurs (turbulence from high cardiac output in anaemia, thyrotoxicosis and marked aortic regurgitation)
• Murmurs originating from the pulmonary valve with disease of that valve or atrial septal defect (the pulmonary and aortic areas are very close)

Investigations

• ECG may show evidence of LVH or left ventricular strain.
• Chest X-ray may show cardiac enlargement, calcification of the aortic ring or evidence of other disease. It is often normal except in advanced disease.
• Echocardiography gives a very good indication of flow, obstruction and incomplete emptying. Doppler studies can indicate speed of ejection and give a very good idea of the degree of stenosis or regurgitation. Two-dimensional Doppler echocardiography is the imaging modality of choice.
• It may still be necessary to undertake cardiac catheterisation to measure pressures across the valve to assess the severity of disease and the need for intervention. Coronary arteriography is also performed in patients over the age of 40 as there is a 50% chance of coronary heart disease (CHD) too. Angina can occur without coronary artery disease² but, particularly in the elderly, it is a strong pointer to coronary narrowing too.³
• The risk factors for aortic sclerosis are similar to those for CHD and so similar investigations should be undertaken.^1,4

Management

General measures

• Avoid heavy exertion, especially with AS.
• Educate the patient about the need for prophylaxis against subacute bacterial endocarditis (SBE).

Pharmacological

• If there is heart failure due to aortic valve disease it will need to be treated in the usual way. ACE inhibitors can reduce left ventricular mass.
• In AR, vasodilators should be used with care, if at all.⁵
• Aortic sclerosis and stenosis in the older age group, should be seen as a strong risk for ischaemic heart disease and appropriate steps should be taken.⁶ Statins may even delay progress of the disease but ACE inhibitors do not.⁷

Failure of medical therapy is an indication for surgery.

Surgical

It is possible to replace the diseased valve under cardiopulmonary bypass. As heart valves display very little in terms of tissue antigens it is possible to use xenografts, such as pig's valves, without fear of rejection. Prosthetic valves are a variation of the original Starr-Edwards valve. It produces a very loud noise that can often be heard across a quiet room and it requires long-term anticoagulation to prevent thromboembolism. In pure stenosis it may be possible to dilate the valve. This can be done by balloon inflation at angiography.

Surgery is a major procedure but it should best be undertaken before heart failure becomes established.⁸ Many of the adverse effects will reverse after surgery but, if severe, they may persist.⁹

Particularly in adults with AS, balloon valvotomy may be undertaken but it is usually as a palliative procedure, especially in those too ill to undergo surgery.¹⁰

Complications

Damaged valves are susceptible to SBE and appropriate precautions must be taken. The risk with disease of old age is rather less than in younger patients but it can occur and precautions should be taken in older patients too.

Calcified AS may produce small systemic emboli. The effect will depend upon where they lodge.

Prognosis

• Aortic valve disease will eventually lead to decompensation with raised end-diastolic pressure, increased pressure in the pulmonary system and congestive heart failure.
• After the onset of AS symptoms, the average survival is only two to three years. Unfortunately, at least 1-2% of asymptomatic patients die suddenly or have very rapid rate of progression to symptomatic stage and then to sudden death.¹
• After diagnosis of AR, those who are asymptomatic with normal left ventricular function have a 5-year survival rate around 75%, falling to 50% at 10 years.
• Sudden death occurs in less than 0.2% of patients per year.
• In asymptomatic patients with left ventricular systolic dysfunction, there is progression to cardiac symptoms in more than 25% per year.
• In symptomatic patients, the mortality rate is above 10% per year.
• Functional pathology in patients with AR is related to left ventricular volume overload and eventual myocardial dysfunction.
• Of those who develop the features of angina, syncope or heart failure, the approximate interval from the onset of symptoms to death is 2 years for heart failure, 3 years for syncope, and 5 years for angina.
• Even in the absence of significant obstruction, aortic sclerosis in the elderly is associated with a 50% increase in the risk of death from myocardial infarction.¹¹
• The prognosis in even mild or moderate stenosis should not be underestimated, as the outcome is rather poor.¹²

Prevention of subacute bacterial endocarditis

Bacteraemia can result in vegetations forming on damaged or abnormal valves. Anything that can cause a transient bacteraemia, including dental surgery, has traditionally required antibiotic cover.
In 2006 the Working Party of the British Society for Antimicrobial Chemotherapy (BSAC) reviewed the evidence from the American Heart Association (AHA), European Society of Cardiology (ESC) and British Cardiac Society (BCS) as well as other sources.¹³ They also noted a Cochrane review which failed to find any benefit from prophylactic antibiotics before dental surgery in at-risk patients.¹⁴ NICE currently recommends offering people at risk of infective endocarditis (IE) clear and consistent information about prevention including:¹⁵

• The benefits and risks of antibiotic prophylaxis, and an explanation of why antibiotic prophylaxis is no longer routinely recommended
• The importance of maintaining good oral health
• Symptoms that may indicate IE and when to seek expert advice
• The risks of undergoing invasive procedures, including non-medical procedures such as body piercing or tattooing

They also advise not offering antibiotic prophylaxis against IE:

• To people undergoing dental procedures
• To people undergoing non-dental procedures at the following sites:
  • Upper and lower gastrointestinal tract
  • Genitourinary tract, including urological, gynaecological and obstetric procedures and childbirth
  • Upper and lower respiratory tract, including ear, nose and throat procedures and bronchoscopy

General dental hygiene appears to be important in those at risk and general background bacteraemia from activities such as cleaning teeth appears to be a greater risk than dental surgery.

Document references

1. Ramaraj R, Sorrell VL; Degenerative aortic stenosis. BMJ. 2008 Mar 8;336(7643):550-5.
2. Julius BK, Spillmann M, Vassalli G, et al; Angina pectoris in patients with aortic stenosis and normal coronary arteries. Mechanisms and pathophysiological concepts. Circulation. 1997 Feb 18;95(4):892-8. [abstract]
3. Dangas G, Khan S, Curry BH, et al; Angina pectoris in severe aortic stenosis. Cardiology. 1999;92(1):1-3. [abstract]
4. Hughes BR, Chahoud G, Mehta JL; Aortic stenosis: is it simply a degenerative process or an active atherosclerotic process? Clin Cardiol. 2005 Mar;28(3):111-4. [abstract]
5. Evangelista A, Tornos P, Sambola A, et al; Role of Vasodilators in Regurgitant Valve Disease. Curr Treat Options Cardiovasc Med. 2006 Dec;8(6):428-434. [abstract]
6. Prasad Y, Bhalodkar NC; Aortic sclerosis--a marker of coronary atherosclerosis. Clin Cardiol. 2004 Dec;27(12):671-3. [abstract]
7. Rosenhek R, Rader F, Loho N, et al; Statins but not angiotensin-converting enzyme inhibitors delay progression of aortic stenosis. Circulation. 2004 Sep 7;110(10):1291-5. Epub 2004 Aug 30. [abstract]
8. Otto CM; Aortic stenosis. Clinical evaluation and optimal timing of surgery. Cardiol Clin. 1998 Aug;16(3):353-73, vii. [abstract]
9. Kumpuris AG, Quinones MA, Waggoner AD, et al; Importance of preoperative hypertrophy, wall stress and end-systolic dimension as echocardiographic predictors of normalization of left ventricular dilatation after valve replacement in chronic aortic insufficiency. Am J Cardiol. 1982 Apr 1;49(5):1091-100. [abstract]
10. Agarwal A, Kini AS, Attanti S, et al; Results of repeat balloon valvuloplasty for treatment of aortic stenosis in patients aged 59 to 104 years. Am J Cardiol. 2005 Jan 1;95(1):43-7. [abstract]
11. Otto CM, Lind BK, Kitzman DW, et al; Association of aortic-valve sclerosis with cardiovascular mortality and morbidity in the elderly. N Engl J Med. 1999 Jul 15;341(3):142-7. [abstract]
12. Rosenhek R, Klaar U, Schemper M, et al; Mild and moderate aortic stenosis. Natural history and risk stratification by echocardiography. Eur Heart J. 2004 Feb;25(3):199-205. [abstract]
13. Guidelines for the prevention of endocarditis (Full Text) Report of the Working Party of the British Society for Antimicrobial Chemotherapy; J Antimicrob Chemother. 2006 Jun;57(6):1035-42
14. Oliver R, Roberts GJ, Hooper L; Penicillins for the prophylaxis of bacterial endocarditis in dentistry.; Cochrane Database Syst Rev. 2004;(2):CD003813. [abstract]
15. Antimicrobial prophylaxis against infective endocarditis, NICE Clinical Guideline (March 2008)

Internet and further reading

• Ren X et al, Aortic Stenosis, Medscape, Apr 2011
• Wang SS; Aortic Regurgitation, eMedicine, Jun 2010
• Aortic valve replacement. Around 8,000 aortic valve replacements are done in the UK each year. The operation is the second most common type of heart surgery performed and, with our increasingly ageing population, this number will grow. Professor David Taggart explains. A short video from NHS Choices. (September 2007)
• Aortic valve real story. Mike Tennant, 73, explains what happened after he was told he needed his aortic valve repaired, and what life is like since the operation. A short video from NHS Choices. (September 2007)

Acknowledgements