Aortic Stenosis And Regurgitation Flashcards
What is aortic stenosis
Aortic stenosis is a chronic progressive disease that produces obstruction to the left ventricular stroke volume leading to symptoms of chest pain, breathlessness, syncope and pre-syncope and fatigue. Aortic valve stenosis includes calcific stenosis of a trileaflet aortic valve, stenosis of a congenitally bicuspid valve, and rheumatic aortic stenosis.
Calcific aortic valvular disease (CAVD) is the commonest cause of aortic stenosis and mainly occurs in the elderly. This is an inflammatory process involving macrophages and T lymphocytes with initially thickening of the subendothelium with adjacent fibrosis.
What are some causes of aortic stenosis
Calcific aortic valvular disease (CAVD) is the commonest cause of aortic stenosis and mainly occurs in the elderly. This is an inflammatory process involving macrophages and T lymphocytes with initially thickening of the subendothelium with adjacent fibrosis.
Bicuspid aortic valve (BAV) is the commonest form of congenital heart disease occurring in 1–2% of live births and in many cases, is familial.
Rheumatic fever can produce progressive fusion, thickening and calcification of the aortic valve. In rheumatic heart disease the aortic valve is affected in about 30–40% of cases and there is usually associated mitral valve disease.
Other causes of valvular stenosis include chronic kidney disease, Paget’s disease of bone, previous radiation exposure, homozygous familial hypercholesterolaemia.
Valvar aortic stenosis should be distinguished from other causes of obstruction to left ventricular emptying, which include:
Supravalvular obstruction – a congenital fibrous diaphragm above the aortic valve often associated with mental retardation and hypercalcaemia (Williams’ syndrome) Hypertrophic cardiomyopathy – septal muscle hypertrophy obstructing left ventricular outflow Subvalvular aortic stenosis – a congenital condition in which a fibrous ridge or diaphragm is situated immediately below the aortic valve.
What are some symptoms of aortic stenosis
There are usually no symptoms until aortic stenosis is moderately severe (when the aortic orifice is reduced to one-third of its normal size). At this stage, exercise-induced syncope, angina and dyspnoea develop. When symptoms occur, the prognosis is poor – on average, death occurs within 2–3 years if there has been no surgical intervention.
Pulse
The carotid pulse is of small volume and is slow-rising or plateau in nature.
Precordial palpation
The apex beat is not usually displaced because hypertrophy (as opposed to dilatation) does not produce noticeable cardiomegaly.
Auscultation
The most obvious auscultatory finding in aortic stenosis is an ejection systolic murmur that is usually ‘diamond-shaped’ (crescendo-decrescendo). The murmur is usually longer when the disease is more severe, as a longer ejection time is needed. The murmur is usually rough in quality and best heard in the aortic area.
What are some investigations which can be made when aortic stenosis is suspected
The chest X-ray usually reveals a relatively small heart with a prominent, dilated, ascending aorta. This occurs because turbulent blood flow above the stenosed aortic valve produces so-called ‘post-stenotic dilatation’. The aortic valve may be calcified.
Echocardiography readily demonstrates the thickened, calcified and immobile aortic valve cusps, the presence of left ventricular hypertrophy, and can be used to determine the severity of aortic stenosis. Transoeophageal echocardiography is rarely indicated.
Cardiac catheterization is rarely necessary since all of this information can be gained non-invasively with echocardiography and CMR. Coronary angiography is necessary before recommending surgery.
These techniques are indicated for assessing the thoracic aorta for the presence of aneurysm, dissection or coarctation but are rarely necessary.
What are some treatment for aortic stenosis
In patients with aortic stenosis, symptoms are a good index of severity and all symptomatic patients should have aortic valve replacement. Patients with a BAV and ascending aorta >50 mm or expanding at >5 mm/year should be considered.
for surgical intervention. Asymptomatic patients should be under regular review for assessment of symptoms and echocardiography. Surgical intervention for asymptomatic people with severe aortic stenosis is recommended in those with:
Symptoms during an exercise test or with a drop in blood pressure A left ventricular ejection fraction of <50% Moderate–severe stenosis undergoing CABG, surgery of the ascending aorta or other cardiac valve.
Antibiotic prophylaxis against infective endocarditis is discussed in Chapter 4. Provided that the valve is not severely deformed or heavily calcified, critical aortic stenosis in childhood or adolescence can be treated by valvotomy (performed under direct vision by the surgeon or by balloon dilatation using X-ray visualization). This produces temporary relief from the obstruction. Aortic valve replacement will usually be needed a few years later. Balloon dilatation (valvuloplasty) has been tried in adults, especially in the elderly, as an alternative to surgery. Generally results are poor and such treatment is reserved for patients unfit for surgery or as a ‘bridge’ to surgery (as systolic function will often improve).
Percutaneous valve replacement
A novel treatment for patients unsuitable for surgical aortic valve replacement is transcatheter implantation with a balloon expandable stent valve.
What is the pathophysiology for aortic regurgitation
Aortic regurgitation is reflux of blood from the aorta through the aortic valve into the left ventricle during diastole. If net cardiac output is to be maintained, the total volume of blood pumped into the aorta must increase, and consequently the left ventricular size must enlarge. Because of the aortic runoff during diastole, diastolic blood pressure falls and coronary perfusion is decreased.
What are some symptoms and signs for aortic regurgitation
Symptoms
In aortic regurgitation, significant symptoms occur late and do not develop until left ventricular failure occurs. As with mitral regurgitation, a common symptom is pounding of the heart because of the increased left ventricular size and its vigorous pulsation. Angina pectoris is a frequent complaint. Varying grades of dyspnoea occur depending on the extent of left ventricular dilatation and dysfunction. Arrhythmias are relatively uncommon.
Signs
Quincke’s sign – capillary pulsation in the nail beds De Musset’s sign – head nodding with each heart beat Duroziez’s sign – a to-and-fro murmur heard when the femoral artery is auscultated with pressure applied distally (if found, it is a sign of severe aortic regurgitation).
Pistol shot femorals – a sharp bang heard on auscultation over the femoral arteries in time with each heart beat.
What are some investigations to make when aortic regurgitation is suspected
Chest X-ray
The chest X-ray features are those of left ventricular enlargement and possibly of dilatation of the ascending aorta. The ascending aortic wall may be calcified in syphilis, and the aortic valve calcified if valvular disease is responsible for the regurgitation.
Echocardiogram
The echocardiogram demonstrates vigorous cardiac contraction and a dilated left ventricle. The aortic root may also be enlarged.
Cardiac catheterization
Cardiac catheterization is required to assess for coronary artery disease in patients requiring surgery. During cardiac catheterization, injection of contrast medium into the aorta (aortography) will outline aortic valvular abnormalities and allow assessment of the degree of regurgitation
What are some treatments in aortic stenosis
The underlying cause of aortic regurgitation (e.g. syphilitic aortitis or infective endocarditis) may require specific treatment. Patients with acute aortic regurgitation may require treatment with vasodilators and inotropes. ACE inhibitors are useful in patients with left ventricular dysfunction and betablockers may slow aortic dilatation in Marfan patients. Because symptoms do not develop until the myocardium fails and because the myocardium does not recover fully after surgery, operative valve replacement may be performed before significant symptoms occur.
Aortic surgery is indicated:
In acute severe aortic regurgitation e.g. endocarditis
In symptomatic (dyspnoea, NYHA class II-IV, angina) patients with chronic severe aortic regurgitation When asymptomatic with left ventricular ejection fraction
is ≤50%
When asymptomatic with left ventricular ejection fraction >50% but with a dilated left ventricle (end-diastolic dimension >70 mm or systolic dimension >50 mm)
When undergoing CABG, surgery of the ascending aorta or other cardiac valve.
Tissue valves are preferred in the elderly and when anticoagulants must be avoided, but are contraindicated in children and young adults because of the rapid calcification and degeneration of the valves.
Antibiotic prophylaxis against infective endocarditis is not recommended.
