Setting: office or ambulatory care
CC: “I feel short of breath when I push myself.”
VS: R: 12 breaths/minute; BP: 108/72 mm Hg; P: 64 beats/minute; T: 99.8°F
HPI: A 78-year-old man, who was a long-term patient of your partner, presents with exertional dyspnea. Shortness of breath has been occurring for several months. It is slowly getting worse, and he can count the number of steps he must take into his two-storey house before it happens. He now feels light-headed as well.
ROS:
Denies chest pain
Denies loss of consciousness
PMHX:
Hypertension
Hyperlipidemia
Osteoarthritis
Medications:
Enalapril
Hydrochlorothiazide
Ibuprofen
Atorvastatin
PE:
Cardiovascular: systolic murmur, crescendo-decrescendo heard best in the second right intercostal area
Where will the murmur radiate to?
a. Axilla
b. Lower left sternal border
c. Carotids
Answer c. Carotids
Aortic stenosis (AS) murmur will project up the aorta toward the direction of the carotid arteries. MR radiates to the axilla. MR is pansystolic (or holosystolic) and will obscure hearing either S1 or S2. Aortic regurgitation (AR) radiates down the lower left sternal border. AR is a diastolic decrescendo murmur.
Why is there a delay between the closure of the mitral and tricuspid valves (S1) and the beginning of the murmur?
a. Insufficient backflow of blood
b. Rapid aortic filling
c. Isovolumetric contraction
d. Isovolumetric relaxation
e. Shunt circulation
Answer c. Isovolumetric contraction
At the start of ventricular contraction, blood does not move across the aortic valve. It takes time for actin and myosin filaments to shorten and to increase LV pressure to the point where blood moves. Blood does not move until it exceeds diastolic pressure, which is usually around 80 mm Hg. When LV pressure exceeds diastolic pressure, the aortic valve will open and blood will exit the LV and enter the aorta. This is when the murmur occurs.
The murmur of AS is delayed after S1 until LV pressure increases enough to open the aortic valve.
No Blood Movement = No Murmur
On auscultation, maneuvers are performed in the office to see what the diagnosis is, before an echocardiogram is performed. Squatting and leg raise increase venous return to the heart. Standing suddenly and the Valsalva maneuver will decrease venous return to the he art. This patient’s murmur of AS will become louder with squatting and leg raises and quieter with standing and Valsalva maneuvers.
AS narrows the aortic valve. According to the Reynolds number, as diameter decreases, turbulence should decrease. Why does the narrowing caused by AS provide turbulence enough to produce a murmur, if the total flow is decreased?
a. Viscosity increases.
b. Viscosity decreases.
c. Velocity increases more than diameter decreases.
d. Increased filling actually increases total flow in AS.
e. Dilated cardiomyopathy compensates.
Answer c. Velocity increases more than diameter decreases.
Velocity is inversely proportional to surface area. As the surface area decreases, velocity increases. However, the velocity increases with the value of πr2. Hence, you have less blood moving through the aortic valve, much faster. Flow is down, velocity is up. This is what creates the turbulence that produces a murmur that you can hear.
Initial Orders and Results:
Chest x-ray: left ventricular hypertrophy, clear lung fields
ECG: left ventricular hypertrophy
Echocardiogram: aortic stenosis, symmetrical ventricular hypertrophy
Oximeter: normal
The patient returns to discuss the findings with you after several weeks. His symptoms of breathlessness are about the same.
Which therapy will decrease the progression of AS?
a. Diuretics
b. ACE inhibitors
c. HMG-CoA reductase inhibitors (statins)
d. Beta-blockers
e. CCBs
f. None
Answer f. None
No medication has ever been shown to decrease the rate of progression of AS. AS is an idiopathic disorder of increasing fibrosis, sclerosis, and calcification of the aortic valve (Figure 1-2). None of these medications will decrease progression, and some, such as diuretics, can be dangerous in terms of decreasing LV filling pressure.
Figure 1-2. Parasternal long-axis plane demonstrating a thickened, stenotic aortic valve. Ao, aorta; LA, left atrium; LV, left ventricle. (Reproduced with permission from Fuster V, et al., ed. Hurst’s The Heart, 13th ed. New York: McGraw-Hill; 2011.)
You move the clock forward 3 to 6 months on a CCS case. The patient reports worsening dyspnea and he has had an episode of syncope. You recommend valve repair. He is now 79 years old.
Which is best for this patient?
a. Balloon valvuloplasty
b. Open aortic valve commissurotomy
c. Replace with metal valve
d. Replace with bioprosthetic valve
Answer d. Replace with bioprosthetic valve
Balloon valvuloplasty is not a good choice for stenotic aortic valves. The valve will only restenose and worsen. In addition, the procedure may simply create aortic regurgitation. The same is true of an open commissurotomy.
Replacement of aortic valves is clearly the best choice when symptoms of shortness of breath or syncope develop. A bioprosthetic valve is preferred because it does not need anticoagulation with warfarin. On average it will last 10 years, but in an elderly, relatively sedentary person, it may last 15 years. Metal valves need an international normalized ratio (INR) higher than 2 to 3 because metal valves are so thrombogenic. This puts an elderly person at very high risk of bleeding.
The patient refuses to undergo valve replacement surgery. He says, “I’m too old,” and leaves the office. He comes back a few months later. His exercise tolerance has decreased, and he becomes dyspneic even walking across his own living room. He had two more episodes of syncope. He is now ready for valve replacement.
What test should you do prior to surgery?
a. Holter monitor
b. Troponin or CK-MB
c. Arterial blood gas
d. Cardiac catheterization
e. Positron emission tomography (PET) scan
Answer d. Cardiac catheterization
There is a very high incidence of coronary artery disease in those with AS. Frequently, simultaneous coronary bypass surgery is done in 50% to 70% of patients. Troponin and CK-MB testing are only for ACS. A PET scan measures the uptake of 18-fluorodeoxyglucose. It is useful to tell the content of solid lesions to see if there is cancer inside. Cancers generally have an increased metabolic rate of glucose, and the PET scan will light up with a cancer.
Which has the shortest survival in AS?
a. Syncope
b. Angina
c. CHF
d. Left ventricular hypertrophy
Answer c. CHF
By the time the heart dilates in size, nothing can be done to restore it to normal size and shape. This is why replacement of the aortic valve should occur before cardiac dilation has occurred. Angina is the most common and earliest finding of AS and can be easily reversed by coronary bypass surgery.