Disorders of the Aortic Valve for the Physician Assistant Exam
The Physician Assistant Exam will expect you to be able to answer questions about the aortic valve. The aortic valve is located between the left ventricle and the aorta. The two major disorders you can see with the aortic valve are aortic stenosis and aortic regurgitation.
Aortic stenosis (AS) refers to a narrowing of the aortic valve area. Over time, this trileaflet valve becomes calcified. The more severe the narrowing of the valve, the more significant the left ventricular hypertrophy (LVH) that can develop over time.
On physical examination, you can hear a midsystolic murmur as well as a decreased S2, which is best heard at the second right intercostal space. Recall that the S2 refers to a closure of the aortic and pulmonic valves. With aortic stenosis, the A2 part can be diminished or even absent if the aortic stenosis is severe.
Other physical exam findings include pulsas parvus et tardus (weak and late pulse) as well as a narrow pulse pressure. This is the opposite of aortic regurgitation, which has a widened pulse pressure. Aortic stenosis decreases with the Valsalva maneuver.
In terms of the three different (but sometimes overlapping) clinical presentations of aortic stenosis, remember the mnemonic SAD: S = syncope, A = angina, and D = dyspnea. The presenting symptoms in someone with aortic stenosis can actually can help predict, to a degree, his or her life span without intervention:
|Clinical Presentation||Average Life Span|
|AS and dyspnea||2 more years|
|AS and syncope||3 more years|
|AS and chest pressure/angina||5 more years|
Here’s a key point about aortic stenosis: Cardiac chamber catheterization provides a definitive diagnosis. It can directly measure the pressure on both sides of the aortic valve. The pressure gradient may be used as a decision point for treatment. It’s useful in symptomatic patients before a cardiac intervention is planned.
Aortic stenosis can be classified as mild, moderate, or severe. The valve area is normally 1.5–2 cm2. A valve area of about 1 cm2 is classified as moderate aortic stenosis. If it’s < 0.8 cm2, it’s classified as severe aortic stenosis. The narrower the valve area is as measured by echocardiogram, the more severe the presenting symptoms.
You’re evaluating a 65-year-old man who complains of shortness of breath. On physical examination, he has a midsystolic murmur and decreased S2. You also note diminished carotid upstroke bilaterally. Which one of the following is true?
(A) He likely needs a mitral valve replacement.
(B) This murmur would decrease with a Valsalva maneuver.
(C) He would be expected to have a widened pulse pressure.
(D) The cause of the murmur is likely rheumatic fever.
(E) His life span without surgical intervention is at least five years.
The correct answer is Choice (B). This man has aortic stenosis. He would likely need an aortic valve replacement rather than a mitral valve replacement, Choice (A). Regarding Choice (C), he would have a narrow pulse pressure; you’d see a widened pulse pressure with aortic regurgitation.
Rheumatic fever, Choice (D), is a cause of mitral and tricuspid stenosis, and this guy has aortic stenosis with shortness of breath. Regarding Choice (E), his life span without surgical intervention is unfortunately about 2 years.
Aortic regurgitation (AR) is a common murmur. The aortic valve is leaking, and blood flows in the reverse (wrong) direction from the aorta into the left ventricle. The first clue to the presence of aortic regurgitation (also called aortic insufficiency, or AI) is a widened pulse pressure.
Recall that pulse pressure is simply the difference between the systolic and diastolic blood pressures. The wider the pulse pressure, the more significant the aortic regurgitation. You may see a blood pressure like 150/45 mmHg. You can see a widened pulse pressure in isolated systolic hypertension as well. Here are three key points about aortic regurgitation:
In addition to a widened pulse pressure, aortic regurgitation can cause a diastolic murmur (a diastolic rumble).
Causes of aortic regurgitation include endocarditis, acute aortic dissection, syphilis, and the seronegative spondyloarthropathies, including ankylosing spondylitis and reactive arthritis.
With symptomatic aortic regurgitation, surgical intervention — aortic valve replacement (a valve job but with no oil change) — is often warranted. With asymptomatic aortic regurgitation, surgery is indicated only if the ejection fraction is <= 50 percent.