Aortic stenosis is a progressive valvular disease, resulting in obstruction of blood flow through the aortic valve. One of the most prevalent heart diseases in the Western world, aortic stenosis is attributed to degenerative calcification of the valvular leaflets in senior patients. However, in the younger population, aortic stenosis typically results from a congenital bicuspid valve.
The clinical picture consists of the SAD triad: syncope upon physical exertion, angina and dyspnea. Other symptoms associated with AS are related to cardiac failure, such as paroxysmal nocturnal dyspnea, orthopnea, and dyspnea on exertion. Arrhythmias such as the potentially fatal ventricular fibrillation can also occur.
Exertional syncope, which is the most common complaint, stems from the inability of CO to meet physical demands in the setting of systemic vasodilatation. Seizures can occur with syncopic phenomena .
Heart failure may develop from various pathophysiological mechanisms such as diastolic or systolic dysfunction. The former is a consequence of LVH or ischemia, while systolic failure is a result of afterload mismatch, ischemia or another pathological condition. Finally, tachyarrhythmias and heart blocks can also contribute to heart failure.
Other complications include gastrointestinal bleeding secondary to angiodysplasia and symptomatology consistent with bacterial endocarditis. Also, aortic stenosis can produce calcium emboli, even though such a complication is rare.
A physical exam reveals findings consistent with aortic stenosis. Patients tend to exhibit diminished carotid and peripheral pulses. Moreover, the clinician can palpate a sustained apical impulse, which is indicative of LVH.
Regarding cardiac auscultation, the characteristic murmur reflects a crescendo-decrescendo ejection pattern. This is heard at the right and left upper sternal border as the patient tilts forward while sitting.
A vital component of the workup is a detailed medical history as it can confirm suspicion arising from a patient’s clinical presentation and co-evaluate underlying health conditions. In addition, a physical exam including careful auscultation can provide important clues.
While the diagnosis is established clinically, there are indicated studies as well. A 2-D transthoracic echocardiogram is the initial test for the classic presentation of aortic stenosis . This demonstrates stenosis, measures LV wall thickness, and detects the severity of systolic dysfunction, alongside the diagnosis of any other valvular disorders or cardiac conditions. A doppler echocardiogram can quantify the jet velocity and transvalvular gradient, thus illustrating the severity of the stenosis.
Cardiac catheterization is also required, in order to determine the presence of coronary artery disease (CAD). An electrocardiogram (ECG) is necessary since it depicts arrhythmias, ischemic changes, and LVH. Moreover, an exercise stress test can be performed in asymptomatic cases but not in symptomatic patients.
Other helpful imaging modalities include radiographs and CT scans. A chest x-ray is obtained to detect congestive heart failure, the size of the heart, and the presence of calcification in the aortic valves. X-ray findings in early and late aortic stenosis differ. In the latter case, it may show cardiomegaly, edema, and other findings suggestive of congestive heart failure. Finally, cardiac CT displays aortic valve calcification which may be correlated with severe stenosis .
AVR constitutes a definitive treatment of symptomatic patients as well as asymptomatic individuals with LV dysfunction. In this procedure, the valve is replaced with a mechanical or prosthetic substitute. In younger individuals, the pulmonic valve can be used to replace the aortic valve, while the pulmonic valve can be substituted by a prosthetic one: this is known as the Ross procedure. Children with severe stenosis may undergo surgery prior to developing symptoms.
While surgical AVR is the optimal therapeutic intervention in the majority of patients, transcatheter valve replacement (TAVR) is the alternative for poor surgical candidates. The TAVR option is safer for high-risk patients and provides improvement to the quality of life and mortality, when compared to treatment with medications.
As for patients affected by AS and deemed ineligible candidates for a surgical procedure, percutaneous balloon valvuloplasty can be performed for palliative purposes.
Patients with coexisting coronary heart disease can undergo a combined AVR and bypass graft surgery (CABG).
Drug therapy is challenging in aortic stenosis patients. If vasodilators, such as nitrates, are used, caution should be exercised since these medications can cause hypotension and other physiological effects that may exacerbate stenosis. Any therapy, if indicated, should be utilized carefully. Finally, statins have not demonstrated the capacity to hinder the progression of aortic stenosis .
Lastly, individuals with aortic valve stenosis do not require antibiotic prophylaxis for bacterial endocarditis .
An aggressive type of AS results in a worse outcome, as the flow through the aortic valve can become substantially diminished. Therefore, patients with aortic stenosis require close follow-up and monitoring.
The prognosis for patients with severe, symptomatic aortic stenosis is poor, with the average survival rate being 2 to 3 years prior to surgery. Half of the deaths in individuals with severe aortic stenosis are sudden. Hence, patients with this illness should minimize any physical exertion.
Asymptomatic patients with severe stenosis can remain so for a decade or more, even with LV outflow tract obstruction (LVOTO). The latter may have a genetic component as 20% of patients were observed to have first-degree relatives exhibiting undiagnosed bicuspid aortic valves .
The prognosis for asymptomatic patients is excellent. The mortality rate is less than 1% annually. However, 3% to 6% of asymptomatic patients exhibit symptoms every year. A grading classification for aortic valve stenosis provides insight into the clinical outcome in asymptomatic patients .
As for surgical intervention in asymptomatic patients, the risks outweigh the benefits. When symptoms present, however, valvular replacement is a prudent decision regarding survival and symptom relief.
The cause of aortic stenosis varies in different age groups. For example, senior patients exhibit AS on the grounds of aortic sclerosis, which is characterized by fibrotic and calcified valve leaflets. Stenosis leads to a progressive, degenerative obstruction in this population.
In patients under 70 years of age, most cases are attributed to a congenital bicuspid aortic valve. Other valvular defects such as unicuspid, tricuspid and quadricuspid valves also result in aortic stenosis. In newborns and children under 12 months old, a unicuspid valve results in marked obstruction as well as mortality.
Rheumatic fever is the most common cause of aortic stenosis in all ages in developing countries.
Calcific or degenerative aortic stenosis, which is more common in males, presents in patients older than 75 years old . It is a gradual process that develops over a decade or more. The prevalence of calcific aortic stenosis in this age group is 2% to 9%. Furthermore, this type usually occurs in predisposed patients with risk factors for atherosclerosis . Aortic sclerosis, which precedes calcific aortic stenosis, also exhibits a frequency that increases with age.
Congenital aortic stenosis, which is usually secondary to unicuspid or bicuspid valves, occurs in 0.33% of live births, with a symptomatic presentation emerging in middle age or later.
Rheumatic aortic stenosis produces symptoms that usually do not manifest until after the sixth decade of life.
The progression of the condition affecting the aortic leaflets involves lipid deposition in addition to inflammatory, calcifying alterations of the valve. This progressive degeneration leads to impairment of the valve's function during the process of systole.
As the valve becomes stenotic, a systolic transvalvular gradient develops between the left ventricle (LV) and the aorta. This results in an outflow obstruction and an increased LV systolic pressure. As compensation for the elevated pressure and the stress on the ventricular wall, the LV undergoes hypertrophy without dilatation of the cavity. Over the years, the heart adapts and alters its physiology. Systolic failure is linked to diminished contractility and decreased cardiac output (CO). Likewise, diastolic failure is associated with an increase in LV end-diastolic pressure and a reduction in CO. These pathophysiologic mechanisms contribute to cardiac failure.
It is vital to draw attention to the fact that stenosis progresses slowly. When the left ventricle hypertrophies, it preserves its normal ventricular function and cardiac output for years. However, as illustrated above, systolic function eventually declines in many patients. As for surgical treatment, AVR improves the systolic function unless contractile dysfunction can no longer be reversed .
Reducing risk factors associated with heart disease may prevent aortic stenosis. For example, healthy dietary intake, weight maintenance, smoking cessation/abstinence and proper medical management are beneficial. Furthermore, hypertension, hypercholesterolemia, diabetes, and obesity should all be addressed to prevent disease or progression of the disease.
Aortic stenosis (AS), a potentially life-threatening heart disease, is characterized by the obstruction of blood flow across the aortic valve. As the most common valvular disease, it is frequently observed in the senior population, primarily due to degenerative calcification that occurs with the aging process. AS is a progressive disease that develops over 10 to 15 years. In younger patients it is a congenital defect, but symptoms present later in life. This type is caused by bicuspid or unicuspid valves. Another cause of aortic stenosis is rheumatic fever, although this is rare in developed countries.
The disease process is complex. Initially, the outflow obstruction leads to compensatory left ventricular hypertrophy (LVH) to normalize the pressure in the ventricle. Eventually and over the years, the stenosis results in systolic and diastolic dysfunction.
Some patients exhibit no symptoms, while others exhibit syncope, angina and dyspnea precipitated by physical exertion. The faster the progression, the more severe the aortic stenosis. Asymptomatic patients do have a good prognosis, but once symptoms emerge, a higher mortality rate is observed.
Determining the diagnosis depends on the clinical presentation as well as indicated imaging such as echocardiography. The recommended treatment is aortic valvular replacement (AVR) which improves symptoms and survivability.
Aortic stenosis is a disease of the aortic valve, which is the channel that allows blood to flow from the heart to the aorta. In the senile population, the valve can become narrow and, therefore, less blood travels from the heart to the aorta. In younger people, this disease is congenital, which means they are born with it.
In the early stages of aortic stenosis, it will not necessarily cause symptoms, because the heart adapts to the changes. The disease continues to develop slowly over the next decade or so. Eventually, symptoms emerge, and the condition becomes more severe. The main symptoms are fainting during physical activity, chest pain, and shortness of breath. These occur partly because the heart cannot pump adequate blood to meet the required demands.
The doctor will ask about all your symptoms and medical history. Then they will listen to your heart to determine if there are any murmurs. Following this, you will have a heart ultrasound. This is called an echocardiogram, and it will show how narrow the valve is. It also provides further analysis of the heart and its function.
The best treatment for those with symptoms is surgery, called aortic valve replacement in which the defective valve is substituted by a mechanical or prosthetic one. This procedure usually improves the symptoms and survivability of the patient. If it is too risky for a patient, a balloon valvotomy is a good option.