Aortic Stenosis
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Introduction
The Case of...
a simple case introducing clincial presentation and calling for a differential diagnosis to get students thinking.
Causes and Risk Factors
Aortic stenosis is the most common of all valvular abnormalities and is usually the consequence of calcification due to progressive 'wear and tear'. Incidence rates are higher for people with bicuspid valves, about 1% of the population.
As the population ages, incidence is rising. It primarily comes to attention in the 60's-70's with bicuspid valves but not until the 80's-90's with previously normal valves.
Rheumatic fever can also cause aortic stenosis, but is decreasing in prevalence as a cause.
Pathophysiology
Congenital stenosis leads to fusion of the valve, leaving only a small opening, creates extra work for the heart and results in LV hypertrophy and a murmur.
Aortic stenosis leads to gradual outflow obstruction, resulting in left ventricular hypertrophy.
Calcium heaps up within the aortic cusps, protruding into the surfaces and preventing opening.
A gradually increasing pressure gradient can reach 100 mmHg in severe cases, where the valve area is 0.5-1cm2, compared to the normal 4 cm2. A valve area less than 0.7 cm2 is considered severe.
Left ventricular hypertrophy results.
Signs and Symptoms
- history
- physical exam
History
Patients can be asymptomatic for many years, but developing myocardial ischemia can lead to angina, and congestive heart failure can follow. Syncope is considered the third cardinal symptom.
Physical Exam
On physical exam, laterally displaced and sustained apical impulse can occur with left ventricular hypertrophy. A harsh, crescendo-decrescendo systolic ejection murmur can be heard. Carotid impulse is often diminished and delayed (pulsus parvus et tardus). An S4 heart sound may be heard. A2 can be diminished, and S2 can be paradoxically split.
Investigations
- lab investigations
- diagnostic imaging
Lab Investigations
Diagnostic Imaging
ECG principally shows left ventricular hypertrophy. Left bundle branch block is also common. Echocardiography is the most useful diagnostic test, and can reveal the cause and extent of obstruction. Cardiac catheterization can confirm the diagnosis and evaluate for coronary artery disease.
Differential Diagnosis
Treatments
Medical treatment is ineffective, prompting relief through surgery. This is best done when left ventricular systolic function is preserved.
Balloon aortic valvuloplasty is most effective in young patients, while replacement is the treatment in most older folks.
Consequences and Course
Most asymptomatic people have excellent prognosis.
For this with symptoms of angina or CHF, cardiac compensation has been exhausted and 50% of people will die within 5 years.
Resources and References
Topic Development
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