Resident Version Aortic Stenosis Module Created by Dr. Kye Park

Resident Version

Aortic Stenosis Module

Created by Dr. Kye Park

Objectives:
1. Identify the major causes of aortic stenosis

2. Understand the underlying pathophysiology of aortic stenosis

3. Define how aortic stenosis is classified

4. Know the indications for when surgical valve replacement is warranted

References:

1. 
   Carabello BA. Aortic Stenosis. NEJM 2002;346(9):677-82.
   
2. 
   Bonow et al. ACC/AHA Practice Guidelines. JACC;2006;48(3):e1-148.
   
3. 
   Otto et al. Medical Knowledge Self Assessment Program 14 (MKSAP). 2006. American College of Physicians.
   

CASE

HPI: 60 year old man comes to your office for routine physical. He has been told that he has a murmur of some kind by his previous doctor. He walks 5 miles everyday without any symptoms and his exercise tolerance has not changed in the last few years. He has not noticed any swelling in his legs, shortness of breath when he lies down.
Past Medical History:

Hypertension

Hyperlipidemia

Abdominal Aortic Aneurysm

Medications:

ASA 81 mg PO daily

Metoprolol 25mg PO daily

Atorvastatin 40mg PO daily

MVI daily
Allergies: none
Family History: brother with heart attack at age 57.

Social History: works as an accountant. Denies smoking, alcohol or illicit drug use.
Physical Exam: Vitals: T_m 99.5, P 80, R 16, BP 154/83 O₂ sat 98% on RA

General: comfortable, NAD, A/Ox4

HEENT: PERRL, EOMI

Lungs: CTA bilaterally

CV: RRR, 3/6 late-peaking systolic ejection murmur at 2^nd right intercostals space radiating to the neck. Single S₂. No S₃ or S₄. Carotid upstroke is normal.

Abdomen: soft NTND, normal bowel sounds.

Ext: no clubbing, cyanosis, or edema.
Labs: CBC, Chemistries, LFT’s are within normal limits
ECG: normal
Transthoracic echocardiogram:

Normal systolic function, heavily calcified aortic valve. Peak gradient 64 mm Hg,

Mean gradient of 50 mm Hg. Calculated valve area is 0.7 cm².


What is the next step in the management of this patient?
Discussion Outline:
1. Pathophysiology of Aortic Stenosis

1. 
   Most common cause of AS in adults is calcification of a normal trileaflet or congenital bicuspid valve.
   
2. 
   An active disease process similar to atherosclerosis, characterized by lipid accumulation, inflammation, and calcification.
   
3. 
   Over time, left ventricle adapts to systolic pressure overload through hypertrophy. However, if relative wall thickness does not increase in proportion to pressure, wall stress increases and the high afterload decreases the ejection fraction. Depressed myocardium contractility is also thought to play a part in decreased EF. This eventually leads to systolic/diastolic dysfunction producing symptoms of congestive heart failure.
   

2. Symptoms

Classic symptoms include syncope, heart failure and angina. However, most patients initially present with more subtle symptoms, such as decreased exercise tolerance of dyspnea on exertion.

3. Disease Classification:

1. 
   Mild: (area 1.5 cm², mean gradient < 25 mm Hg, or jet velocity < 3.0 m/s)
   
2. 
   Moderate: (area 1.0 to 1.5 cm², mean gradient 25 to 40 mm Hg,
   

or jet velocity < 3.0 to 4.0 m/s)

3. 
   Severe: (area < 1.0 cm², mean gradient > 40 mm Hg, or jet velocity > 4.0 m/s)
   

4. Management of the Asymptomatic Patient with severe AS:

1. 
   Asymptomatic patients have mortality outcomes similar to age-matched normal adults. Therefore the risks of surgery generally outweigh the benefits.
   
2. 
   However, disease progresses rapidly, requiring more frequent monitoring. Recommended frequency of monitoring:
   
   1. 
      Mild AS: TTE every 3-5 years
      
   2. 
      Moderate AS: every 1-2 years
      
   3. 
      Severe AS: every year
      
3. 
   Medical therapy has not been shown to prevent or delay the disease process.
   
4. 
   Aortic valve replacement in asymptomatic patients is controversial, though there is general agreement that asymptomatic patients with normal LV systolic function should NOT undergo valve replacement.
   
5. 
   Potential exception: patients with clinical or echocardiographic parameters suggestive of rapid disease progression. This is indicated by:
   
   1. 
      Aortic jet velocity > 0.3 m/s or decrease in valve area > 0.1 cm²/year.
      
   2. 
      ECG with LVH and echo showing smaller aortic valve area predict development of early symptoms.
      
6. 
   Exercise testing can identify limited exercise capacity, abnormal blood pressure responses, or exercise induced symptoms in patients with severe AS, and may assist in determining who may benefit from early surgery (ACC/AHA Class IIb indication).
   

^{†see classification scheme below}

5. Management of the Symptomatic Patient with severe AS:

1. 
   Aortic valve replacement (AVR) is the only effective treatment. Younger patients with congenital of rheumatic AS may be candidates for valvotomy. AVR dramatically improves both symptoms and survival.
   
2. 
   Indications for Aortic Valve Replacement (ACC/AHA Class I indications)^*:
   
   1. 
      Severe AS and symptomatic
      
   2. 
      Severe AS undergoing concurrent CABG
      
   3. 
      Severe AS undergoing surgery of the aorta or other heart valves
      
   4. 
      Severe AS with LV dysfunction (EF < 50%)
      

^{*assuming no severe comorbities. Age is NOT a contraindication to surgery.}


Algorithm for approaching severe AS:


Bonow et al. ACC/AHA Practice Guidelines 2006. JACC;48 (3):e1-148.

6. Other indications for AVR:

1. 
   Moderate AS undergoing CABG or surgery on aorta or other heart valves (Class IIa).
   
2. 
   Mild AS undergoing CABG when there is evidence of moderate to severe valve calcification (Class IIb).
   
3. 
   Asymptomatic severe AS when patient’s expected operative mortality is 1.0% or less (Class IIb).
   

^† ACC/AHA Classification of recommendations:

Class I indication: procedure should be performed

Class IIa: reasonable to perform procedure

Class IIb: may consider procedure

Class III: no benefit

Review Question:
1. An 82-year-old woman presents for her annual examination. She has hypertension and is on chronic β-blocker therapy. She denies all cardiac symptoms. She takes a daily 1-mile walk, and her exercise tolerance has not changed during the past year. Physical examination shows a blood pressure of 138/86 mm Hg, a regular pulse of 80/min, and a respiratory rate of 16/min. Her JVP is 10 cm H₂O, her carotid upstrokes are normal, and her lungs are clear. Cardiac examination reveals a normal S₁, a single S₂, and a grade 3/6 early systolic murmur at the upper left sternal border radiating to her carotids. Abdominal examination is benign, and there is 1+ peripheral edema. Lab data are remarkable for a total cholesterol of 210 mg/dL, with an LDL cholesterol of 110 mg/dL. Her echo from 2 years ago showed moderate calcific aortic stenosis, with a maximum aortic velocity of 3.6 m/s (normal < 1.5 m/s) a mean gradient of 30 mm Hg (normal < 5 mm Hg) and a valve area of 1.2 cm² (normal > 2 cm²) with normal left ventricular systolic function. Echo now shows a maximum aortic jet velocity of 4.2 m/s, mean gradient of 44 mm Hg, and a valve area of 1.0 cm² and normal ejection fraction.
Which is the most appropriate next step?

1. 
   Reassurance
   
2. 
   Begin a cardiac rehabilitation program
   
3. 
   Begin hydrochlorothiazide
   
4. 
   Start statin therapy
   
5. 
   Refer for aortic valve replacement
   

2. 79-year-old woman is seen for an annual examination. She is in good health except for osteopenia, for which she takes calcium and Vitamin D supplements. She walks regularly to and from the bus stop several times per week. It takes her 25 minutes to get to the bus stop whereas it only took her 10 minutes a year ago. She describes dyspnea midway in her walk, causing her to stop and catch her breath. She denies angina, presyncope, syncope, or pedal edema. Physical examination shows a heart rate of 80/min, blood pressure of 165/86 mm Hg. Lungs are clear to auscultation. Carotid artery upstrokes are delayed. There is a sustained apical impulse. S₁ is normal and there is a single S₂ and an S₄. A 3/6 late-peaking systolic murmur is heard best at the right 2nd intercostal space, with radiation into the right carotid artery. Transthoracic echo shows concentric left ventricular hypertrophy. The ejection fraction is 69% with no regional wall motion abnormalities. There is a trileaflet aortic valve with heavy calcification, an aortic jet velocity of 4.8 m/s, a peak transaortic gradient of 92 mm Hg, and a valve area of 0.7 cm².
Which is the most appropriate option for improving this patient's quality of life?

1. 
   Begin an angiotensin-converting enzyme inhibitor
   
2. 
   Percutaneous aortic balloon valvuloplasty
   
3. 
   Aortic valve replacement
   
4. 
   A supervised cardiac exercise program
   
5. 
   Discontinue calcium supplementation
   

Post Module Evaluation
Please place completed evaluation in an interdepartmental mail envelope and address to Dr. Wendy Gerstein, Department of Medicine, VAMC (111).

1) Topic of module:__________________________

2) On a scale of 1-5, how effective was this module for learning this topic? _________

(1= not effective at all, 5 = extremely effective)

3) Were there any obvious errors, confusing data, or omissions? Please list/comment below:
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4) Was the attending involved in the teaching of this module? Yes/no (please circle).

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Attending Resident (R2/R3) Intern Medical student