One of my favorite things to do with students, is to look at my patient schedule for the day, and consider differential diagnoses for certain chief complaints. A great deal can be gained from thinking outside the box with a simple chief complaint.
For example, have you considered all of the diagnoses or conditions that could present with sore throat? How about tachycardia? There is great education and sharpening of diagnostic skills to be made when thinking out of the box.
Let’s consider a 76 year old male who is a new patient to your clinic. He has a chief complaint of syncope on exertion. His past medical history is almost non-existent.
He had his gallbladder removed twenty years ago, takes Lisinopril for hypertension, drinks “once per year” and smokes one pack of cigarettes per day for the last 50 years.
As a student or clinician, it is always important to begin with a broad differential and work quickly to narrow it.
The differential diagnosis for exertional syncope is massive. Sometimes narrowing the differential by organ system can be helpful. Certainly cardiac, pulmonary, gastrointestinal, hematological, and neurologic diagnoses would all be possible for this patient.
When we consider the amount of lab testing, blood work, diagnostic imaging tests we could perform, it can be hard to begin to prioritize which should be ordered first, and how quickly.
In today’s article, we will cover from start to finish aortic stenosis, a commonly tested and clinically relevant diagnosis that can present as syncope on exertion.
What is Aortic Stenosis?
Aortic stenosis is a narrowing or stenosis of the aortic valve. Although the disease may go undetected for a number of years, its’ onset is harrowing and can present significant morbidity and mortality for patients.
The disease is thought to impact about 1% of patients age 65 to 74. The incidence of disease increases with age and about 4% of patients older than 84 have aortic stenosis.
Aortic stenosis is also a disease of the young, as 1 to 2 percent of the population has a bicuspid aortic valve which leads to stenosis earlier in life (Bhatia, Ghotra and Stoddard, 2016).
Pathophysiology of Aortic Stenosis
A good knowledge of the pump function of the heart is helpful to understand aortic stenosis. When the aortic valve becomes stenotic, a left ventricular outflow obstruction will develop.
Afterload thus increases, creating more stress for the heart to pump blood forward. Cardiac output will decrease. As a compensation method, the left ventricle pressure will increase, leading to left ventricular hypertrophy.
The resulting decrease in cardiac output may cause syncope, as in our above hypothetical patient.
Risk factors for aortic stenosis include presence of a bicuspid aortic valve, which is responsible for disease earlier in life. Rheumatic fever is also a cause of aortic stenosis, but has become rare.
The most common etiology is in relation to degenerative plaque/calcium build up on the valve. Contributors to increased calcification of valves include high cholesterol, smoking, hypertension, male sex, and age.
There is also a high incidence of hypertension and coronary artery disease in patients with aortic stenosis.
Signs and Symptoms of Aortic Stenosis
Patients presenting with aortic stenosis may complain of chest pain, lightheadedness, or dizziness. The classic triad of aortic stenosis is syncope, angina, and dyspnea on exertion – this is commonly tested.
Angina is the most common symptom.
Patients may also complain of heart failure symptoms such as fatigue, dyspnea, and difficulty with ambulation, orthopnea, or paroxysymal nocturnal dyspnea.
In the elderly, symptoms may be vague, so suspicion of valvular disease must remain on the differential.
The physical exam of a patient with aortic stenosis remains extremely important. As mentioned above, other causes of syncope should be interrogated via a thorough and comprehensive history and physical.
The main abnormality on exam is with auscultation of the heart. Patients with AS will have a harsh, systolic, crescendo decrescendo murmur that is best auscultated at the 2nd right sternal border, or aortic area. The murmur is classically described on exams and will classically radiate up to the carotid arteries.
Further exam findings may find fluid overload due to resultant CHF. Auscultation of the lung fields can show rales at the bases. Lower extremity edema is also common.
Diagnostic imaging is important to confirm the diagnosis and grade severity of stenosis. A chest x-ray may give some information such as a calcified aortic valve on lateral view or cardiomegaly.
An ECG is usually normal but can clue the provider in if there is left ventricular hypertrophy or other evidence of comorbid CAD.
The mainstay of diagnosis is the echocardiogram. This simple test can grade severity of stenosis, assess left ventricular wall thickness, ejection fraction, and function. The severity of aortic stenosis is based on the mean pressure gradient, area, and jet velocity. An experienced lab will grade the stenosis.
Another modality for diagnosis is the exercise stress test. This can be used to identify angina, subtle symptoms such as dyspnea, or blood pressure changes in the asymptomatic patient. It can also demonstrate EKG changes.
The test should be stopped if patients develop symptoms and must not be used in patients who are symptomatic, as this could cause hypotension and ventricular tachycardia.
A cardiac catheterization is a viable option if there is high suspicion for comorbid coronary artery disease.
The main treatment for severe and symptomatic aortic stenosis is surgical.
There is no medical therapy that is preventive for developing the disease, but comorbid conditions such as hypertension should be managed appropriately.
The indications for surgery include patients with symptoms, or patients with severe stenosis without symptoms.
Given the long period of compensation by the left ventricle, patients may present late in the disease.
As with any surgical procedure, patients with other comorbid conditions should weigh the risks and benefits of surgery. Patients with severe, symptomatic aortic stenosis may benefit from trans-catheter aortic valve replacement. This should be performed by an experienced institution.
Patients with severe aortic stenosis whom do not undergo surgical intervention or are deemed poor candidates have a life expectancy of only two to three years. Patients with only mild aortic stenosis or no symptoms can be monitored with serial echocardiograms every one to two years or three to five years for mild disease. Patients with no symptoms have no physical restrictions, but patients with angina or other symptoms should avoid strenuous activity.
A Quick Recap
Aortic stenosis is a narrowing of the aortic valve due to a bicuspid aortic valve or calcified plaque buildup. Given its’ long period of asymptomatic compensation by the left ventricle, it may only become symptomatic when stenosis is severe.
Patients may complain of syncope, angina, or dyspnea, but symptoms may be vague. The mainstay of diagnosis and grading severity is the echocardiogram. The definitive treatment of choice is trans-catheter aortic valve replacement.
Bhatia, N., Ghotra, A.S. and Stoddard, M.F (2016). Aortic Valvular Stenosis. The Five Minute Clinical Consult.
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