Aortic stenosis (AS) refers to a condition where the aortic valve is narrowed. Aortic valve regulates blood flow between the heart and the major artery supplying the body, is narrowed. The prevalence of AS increases with age, ranging from 0.2% in those between 50-59 years to 9.8% in those between 80-89 years. Aortic stenosis is often asymptomatic until there is severe narrowing of the valve.
Causes of Aortic Stenosis
Congenital bicuspid aortic valve: This is an abnormal valve with two leaflets (normal is three), that has been present since birth. Individuals with this condition have an increased risk of calcium deposition in the valve and can present with symptoms of AS at an earlier age.
Calcification of a normal valve: With increasing age and wear and tear of the valve, there is an increased risk of calcification. This accounts for the increasing prevalence of AS with age.
Rheumatic heart disease: This is a condition affecting the heart and its valves as a consequence of a streptococcal sore throat. This is seen predominantly in developing countries where there is overcrowding and poor access to health care.
Symptoms of Aortic Stenosis
Aortic stenosis is usually asymptomatic. The onset of symptoms is a warning sign of severe disease and requires immediate attention by a health care provider. There are three classic symptoms, all of which are made worse by exercise or other exertion.
The diagnosis of AS is generally suspected from the history of symptoms and confirmed by the following
Physical exam: The doctor will look, feel and listen to your chest and heart. Extra heart sounds, referred to as murmurs, can suggest disease in the heart valve.
Echocardiogram: This test enables the use of ultrasound waves to provide a picture of the beating heart. It helps to visualise the heart and its valves in real time to see the size of the aortic valve and to evaluate severity of the disease.
Cardiac catheterisation: This test is invasive and uses a thin wire inserted into am artery or vein to reach the heart and make accurate measurements of the blood flow and pressure across the valve, to give additional information.
Electrocardiogram (ECG): This measures the electrical activity of the heart and can pick up any abnormal heart rhythm which can place the individual in a greater risk for complications.
Chest X ray: This can tell us the size of the heart and can show if the lungs are affected from the AS.
Treatment of Aortic Stenosis
The decision to treat AS depends on the presence or absence of symptoms. Asymptomatic individuals found to have AS may be followed up to keep track of progression of the disease. Regular physical activity may be continued however strenuous activity is to be avoided in case of severe disease.
If there are symptoms or if the AS is severe, the following treatment options can be considered:
Surgical aortic valve replacement (SAVR): This involves open heart surgery. The surgeons would remove the damaged and stenosed aortic valve and replace it with a new valve made from metal or skin from animals.
Transcatheter aortic valve replacement (TAVR): This is a minimally invasive procedure where a small cut is made into the femoral artery and a wire holding an expandable prosthetic valve is inserted into the artery. The prosthesis is placed at the valve site. This is preferred for individuals who cannot undergo surgery
Percutaneous aortic balloon Valvuloplasty (PABV): This procedure involves inserting a wire through the artery with a balloon at its tip. The balloon is inflated at the level of the stenosed valve to make the area wider. This is often not curative and is usually done to bridge the treatment to TAVR.
Medical therapy: Drugs cannot definitively cure the disease. Medicines to control the chest pain and blood pressure may be administered to help with symptoms.
Monitoring of Aortic Stenosis
It is important to monitor for progression of AS in asymptomatic individuals using echocardiogram. The size of the open valve, the blood flow and pressure gradient across the valve is recorded at each instance to estimate severity and progression. This will help decide if corrective procedures are indicated. Generally monitoring is carried out every 3-5 years if mils stenosis is present and annually for severe ones.
Complications of Aortic Stenosis
Heart Failure: The constantly high pressure in the left ventricle that has to pump against the narrowed valve results in failure over time.
Pulmonary Hypertension: The increase in pressure in the heart can reflect back into the blood vessels in the lungs leading to pulmonary hypertension. This is a severe complication with poor prognosis.
Sudden Cardiac Death: The structural changes in the heart that arise due to the AS can lead to abnormal heart rhythms or arrhythmias and can cause sudden death.
Prognosis of Aortic Stenosis
Severe, symptomatic AS when untreated almost certainly leads to death. There is a rapid progression of the disease with >80% of patients dying within 4 years of experiencing symptoms. Procedures to replace the valve is highly beneficial in reducing the chance of death and in improving quality of life.
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