77 AORTIC VALVULAR DISEASE
Christopher D. Raeburn M.D., Alden H. Harken M.D.

1. What are the most common causes of aortic stenosis?

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Rheumatic heart disease is now a rare cause of aortic stenosis, so the most common causes are now congenital anomalies and calcific (degenerative) disease.

2. What is the most common anatomic anomaly in aortic stenosis?

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Bicuspid aortic valve (normal valve is tricuspid) occurs in 2% of the general population. More than 50% of patients with aortic stenosis older than age 15 years have a bicuspid aortic valve.

3. What are the most common symptoms of aortic stenosis in adults? Infants?

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Most patients with aortic stenosis are asymptomatic. In adults, the development of angina, syncope, or dyspnea on exertion (congestive heart failure [CHF]) portends a poor prognosis unless valve replacement is performed. CHF is the most common presentation of aortic stenosis in infants.

4. What is the expected survival of patients with aortic stenosis?

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Asymptomatic patients with aortic stenosis have a near normal life expectancy. After symptoms occur, the 3-year mortality of patients who do not undergo valve surgery is 75%. Thus, it is important to catch patients before they are symptomatic.

5. What is the most feared complication of aortic stenosis?

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Sudden death.

6. What physical findings suggest aortic stenosis?

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Systolic crescendo-decrescendo (diamond-shaped) murmur, diminished peripheral pulses, or delayed pulse upstroke (call it pulsus parvus et tardus if you want to shine on medicine rounds).

7. What are the typical findings of aortic stenosis on chest radiographs and electrocardiogram (ECG)?

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Both chest radiographs and ECG may show normal results even with severe aortic stenosis; thus, these are not good screening tests. On chest radiograph, calcification of the aortic valve and an enlarged cardiac silhouette may be seen. ECG is fairly sensitive in detecting left ventricular hypertrophy (LVH) and may also reveal conduction defects (these occur secondary to extension of valvular calcification into the adjacent conduction tissue).

8. How is the diagnosis of aortic stenosis confirmed?

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Echocardiography with Doppler ultrasound is nearly 100% accurate in diagnosing hemodynamically significant aortic stenosis. This noninvasive test also accurately estimates aortic valve area and gradient and has all but replaced cardiac catheterization as the diagnostic test of choice for aortic stenosis.

9. When is cardiac catheterization indicated in patients with echocardiography-confirmed aortic stenosis?

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Approximately 50% of patients with aortic stenosis will have some degree of associated coronary artery disease (CAD). Patients requiring aortic valve replacement who have surgically treatable CAD should have coronary artery bypass graft (CABG) performed at the time of the valve surgery. Thus, coronary angiography should precede aortic valve surgery in patients ≥ 40 years or in those with angina or significant risk factors for CAD.

10. When is an operation indicated for aortic stenosis?

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Asymptomatic patients with aortic stenosis rarely require surgery; however, essentially all patients with symptomatic aortic stenosis should undergo aortic valve replacement. Indications for valve replacement in asymptomatic patients include progressive LVH, left ventricular dysfunction, or valve area < 0.6 cm2.

11. Can aortic valvotomy be used to treat aortic stenosis?

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Although valvotomy effectively palliates patients with congenital aortic stenosis, it is rarely curative. Most children with the condition will require aortic valve replacement later in life. Aortic valve replacement, not valvotomy, is the procedure of choice in adults.

12. What is the Ross procedure?

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The patient’s own pulmonary valve and proximal pulmonary artery are harvested (autograft) and used to replace the native, diseased aortic valve. A pulmonary allograft (harvested and frozen from a human cadaver) is then used to reconstruct the right ventricular outflow tract.

13. What type of valvular prosthesis should be used in children requiring aortic valve replacement?

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In children younger than 15 years (as well as young adults between the ages of 15 and 30 years), rapid calcification occurs in porcine valves placed in the aortic position. Thus, mechanical valves (or the Ross procedure; see question 12) should be used.

14. What type of valvular prosthesis should be used in adults requiring aortic valve replacement?

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Whether to use a mechanical or a bioprosthetic valve depends upon the patient’s age and the risk of lifelong anticoagulation. Mechanical aortic valves afford excellent long-term relief of hemodynamically significant aortic stenosis but require lifelong anticoagulation. Bioprosthetic valves in the aortic position do not require anticoagulation; however, 30% of these valves exhibit structural deterioration at 10 years.

15. What are the most common causes of aortic insufficiency?

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Infective valvular endocarditis, aortic dissection, connective tissue disease (e.g., Marfan syndrome), and prosthetic (mechanical) valve dysfunction.

16. What physical findings suggest aortic insufficiency?

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A rapid rise and fall of the arterial pulse (refer to this as a water-hammer pulse or, better yet, a Corrigan’s pulse to dazzle your chief medicine resident).

17. What is a Quincke’s pulse?

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Capillary pulsations secondary to aortic insufficiency that can be detected by transmitting a light through the patient’s fingertip or by pressing a glass slide on his or her lip.

18. How is the diagnosis of aortic insufficiency confirmed?

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As with aortic stenosis, echocardiography or Doppler ultrasound are the tests of choice.
KEY POINTS: AORTIC VALVULAR DISEASE

1. The most common causes are congenital anomalies and calcific (degenerative) disease.
2. The most feared complication is sudden death.
3. Surgical intervention is indicated for all patients with symptoms and for asymptomatic patients with left ventricular hypertrophy, left ventricular dysfunction, or valve area < 0.6 cm2.

19. When is an operation indicated for aortic insufficiency?

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This depends on the cause of the aortic insufficiency and whether it is acute or chronic. Aortic insufficiency caused by an ascending aortic dissection is a surgical emergency. Aortic insufficiency secondary to infective endocarditis may or may not require aortic valve replacement (see question 20). Patients with chronic (mild to moderate) aortic insufficiency that does not progress enjoy a near-normal life expectancy. Patients with severe aortic insufficiency require valve surgery before they develop irreversible left ventricular dysfunction. Asymptomatic patients with severe aortic insufficiency benefit from aortic valve replacement when their left ventricle begins to fail or enlarges (end-systolic left ventricular diameter ≥ 55 mm or end-diastolic left ventricular diameter ≥ 75 mm).

20. What are the indications for aortic valve replacement in patients with infective endocarditis?

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Progressive CHF, recurrent septic emboli, infection uncontrolled by antibiotics (often fungal, gram-negative rods or Staphylococcus aureus) and a prolongation of the P-R interval. Although hard to believe, the junction of the left and noncoronary aortic valvular cusps is immediately adjacent to the atrioventricular (A-V) node. Thus, a perivalvular abscess can slow A-V conduction.

21. What is the operative mortality of aortic valve replacement?

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Thirty-day mortality is ≤ 4%. In low-risk patients, the mortality can approach 1%; however, the mortality skyrockets to 20% in patients with associated CAD and left ventricular dysfunction.

22. What are the complications of aortic valve replacement?

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* Bleeding requiring reexploration (2%)
* Heart block (2%), again, caused by the proximity to the A-V node
* Stroke (1%) caused by air or calcium left in the heart after closure of the aortotomy
* Low cardiac output (≥ 5%) in patients with preoperative left ventricular failure

23. What are the long-term results of aortic valve replacement?

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Patients who survive the immediate perioperative period improve both symptomatically and functionally, and age-corrected survival returns to near normal (75% at 10 years). Aortic valve replacement partially reverses LVH and dilatation.

24. Can balloon valvotomy be used for adult calcific aortic stenosis?

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Initially, it was hoped that balloon valvotomy could replace surgery and provide long-term palliation in older patients who are at higher surgical risk because of decreased ventricular function. However, it is exactly this group who fare least well after balloon valvotomy; < 50% are alive at 1 year after surgery.

25. What are the indications for balloon valvotomy?

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Balloon valvotomy is effective in infants and young children with congenital aortic stenosis and a tiny aortic annulus. The intermediate results are similar to surgical valvotomy. In adults, balloon valvotomy should be used primarily as a bridge to aortic valve replacement or transplantation in critically ill patients. Temporary improvement in ventricular function suggests that the patient will benefit from aortic valve replacement. Balloon valvotomy may also relieve the symptoms of women with severe aortic stenosis in the second trimester of pregnancy.

26. Is percutaneous aortic valve replacement feasible?

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Although percutaneous transcatheter placement of a bioprosthetic aortic valve has been reported, this approach is still largely experimental.