Aortic Stenosis and Aortic Sclerosis

Question 1

What is Aortic stenosis?

Answer 1

Aortic stenosis is the narrowing of aortic valvular opening

Question 2

What is the etiology of valvular aortic stenosis?

Answer 2

Congenital – Unicuspid Valve, severe obstruction in infancy – Bicuspid Valve, most common congenital heart defect other than MVP (1-2% live births) – Tricuspid Valve, e.g. fused cusps (rare) Acquired – Rheumatic Valvular Disease, fusion of commisures and cusps with calcific nodules narrow orifice to a small triangular or round opening – Calcific Degenerative Disease, older patients (usually >65 yo) with thickened, calcified leaflets with decreased mobility that open incompletely in systole (incidence is about 3% in the over 75 age group and 9% in the over 85 age group). Other rarer causes: type II hyperlipoproteinemia (homozygous), rheumatoid, ochronosis, SLE, methylsergide, endocarditis, paget’s disease, radiation, end stage renal disease

Question 3

What is the pathophysiology of Aortic stenosis?

Answer 3

• Progression of calcific or degenerative aortic valve disease appears to be an atherosclerotic process. – Similar histology to vascular atherosclerosis with accumulation of extracellular matrix, lipoprotein deposition, infiltration of inflammatory cells including macrophages and T-lymphocytes. Calcification deep within the lesion is common to degenerating aortic valves and atherosclerosis. Lipoprotein oxidation is similar with production of metalloproteinases. – Shear forces and turbulence on the valve appear to predispose to the above processes much the same as atherosclerotic lesions appear at bifurcations in other vascular lesions.

Question 4

Aortic stenosis and the association with other cardiovascular illness?

Answer 4

• 35% increase in risk of stroke if severe AS • 5.7x risk of cardiovascular mortality if severe AS • 50% of patients with severe AS have significant coronary disease.

Question 5

what are the risk factors for aortic stenosis? What has research show may play a role in aortic stenosis?

Answer 5

–Risk factors for atherosclerosis are risk factors for aortic stenosis (and progression). [age, sex, hyperlipidemia, diabetes, smoking, obesity, hypertension, etc.] –Aortic valve atherosclerosis and calcification are increased in experimental hypercholesterolemia in rabbits and this is reduced by atorvastatin. –Retrospective trials have shown reduced progression of aortic stenosis in patients treated with statins.* –Prospective trials with statins have so far been disappointing

Question 6

What is Aortic Sclerosis?

Answer 6

• Aortic Sclerosis (nonobstructive thickening of the valve) appears to have a similar relationship to vascular atherosclerosis in terms of pathology and risk factors. Both entities are associated with other vascular diseases such as coronary disease. • Aortic Sclerosis appears to be a result of the same pathophysiologic process and can represent an early phase of aortic stenosis. In fact, the degree of calcification of the valve predicts the likelihood of progression to significant Aortic Stenosis.

Question 7

Explain the Aortic Valve area as seen with aortic sclerosis? Average rate of narrowing?

Answer 7

–Aortic Valve Area (AVA) • Normal adult: 3-4 cm2 • Mild AS: > 1.5 cm2 • Moderate AS: 1.0-1.5 cm2 • Severe AS < 1.0 cm2 The average rate of narrowing is approximately 0.12 to 0.20 cm2 per year but there is great variability and half the patients may show very little change over periods as long as 3 to 9 years

Question 8

LV output changes how in aortic stenosis/sclerosis? Cardiac Output? Ejection Fraction? If LV failure occurs this is a what sign?

Answer 8

– LV output maintained by concentric hypertrophy due to pressure overload. There is reduced ventricular compliance, reduced coronary blood flow per gram of tissue with less coronary reserve and greater reliance on left atrial contraction. – Over many years increased pressure gradient is necessary to maintain cardiac out put across progressively narrowing valve. – Cardiac output at rest is often normal in severe AS but may fail to rise adequately with exertion. – Ejection fraction is preserved until very late in course.* – If LV failure occurs it is a poor prognostic sign.

Question 9

natural history of Aortic stenosis?

Answer 9

–Long latent (asymptomatic) period –Cardinal symptoms often commence in the 6th or 7th decade for degenerative aortic stenosis and in the 4th or 5th decade for a bicuspid valve. • Angina—50% mortality in 5 yrs • Syncope –50% mortality in 3 yrs • CHF—50% mortality in 2 yrs

Question 10

Symptoms in severe aortic stenosis?

Answer 10

• Angina-usually exertional. Secondary to decreased subendocardial blood flow. This can often manifest as exertional intolerance or dyspnea. • Syncope-usually effort related. Secondary to ‘fixed cardiac output’ and reflex mechanisms (vagal) related to high left ventricular presssure. • Congestive heart failure-late symptom. Secondary to high diastolic pressure, low cardiac output and, very late, pump failure.

Question 11

Sudden cardiac death and Aortic stenosis?

Answer 11

–*Sudden Death occurs in less than 1% per yr of cases of severe AS that are asymptomatic.* –*Sudden death occurs in 15-20% per yr of cases that are symptomatic.* –The average survival after the onset of symptoms is 2-3 yrs.

Question 12

Physical exam findings in the neck for Aortic stenosis?

Answer 12

–Jugular veins, prominent “a” waves –Carotids, pulses small and delayed: pulsus parvus et tardus • +/- shudder • Bruit

Question 13

Aortic stenosis cardiac exam findings?

Answer 13

• Cardiac palpitory exam – Systolic thrill—2nd ICS radiating to suprasternal notch and often to carotids. Sustained apical impulse may be palpable. • Auscultation – Systolic murmur—starts after S1 and is classically a harsh crescendo-decrescendo (‘diamond shaped’ at base and radiating to carotids). - Peak of murmur tends to be more delayed with increasing severity of stenosis. Intensity may roughly correlate with severity if LV function is intact. – S1 is usually nomal – S2 can be soft, single or paradoxically split with inspiration. A normally split S2 makes severe aortic stenosis unlikely. – An S4 is often present suggesting decreased LV compliance. An S3 is uncommon until very late and suggests severe LV dysfunction. – Dynamic auscultation • Murmur decreases with handgrip and valsalva. • Murmur increases after a PVC or pause.

Question 14

What is often heard in young people with congenital Aortic stenosis? What is the Gallavardin phenomenon? What happens to the murmur as Aortic Stenosis progresses?

Answer 14

–Aortic ejection sound (early systolic click) is often present in young people with congenital AS/bicuspid valve. –High frequency components can radiate to the apex (Gallavardin phenomenon). –Very late in the course, with progressive LV failure, the murmur can become much less impressive.

Question 15

What are clinical features that suggest Aortic Sclerosis instead of Aortic stenosis?

Answer 15

• Early peaking systolic ejection murmur associated with normal splitting of S2.* • Good carotid upstrokes (can be misleading in arteriosclerosis) • Grade 2 or less murmur (intensity can be misleading late in AS) • Lack of carotid radiation or thrill • Normal apical impulse • Lack of symptoms or other significant abnormality of the cardiovascular system (coarctation, CHF, etc.) • Normal ECG, CXR , etc. • Very frequently, clinical features are not adequate to rule out Aortic Stenosis especially if mild or moderate (approx. 50% clinical accuracy).

Question 16

Explain EKG findings in Aortic Stenosis?

Answer 16

–Usually NSR –EKG criteria for LVH are present in 75% of patients with severe AS. –LV ‘strain’ pattern is common. –Aortic valve calcification can extend into the AV node & cause conduction defects. –Atrial fibrillation is an uncommon and usually late finding in aortic stenosis.

Question 17

Chest x-ray in aortic stenosis?

Answer 17

–Cardiac size is usually normal because LVH is concentric. –Post-stenotic dilitation of the ascending aorta may be present. –Aortic valve calcification can often be identified.

Question 18

Echo for Aortic Stenosis?

Answer 18

Echocardiography is the single most valuable test for valvular heart disease. – M-mode & 2 dimensional echo can identify thickened and calcified leaflets with decreased opening. Occasionally, the valve area can be traced from a transthoracic echo. – Echo can also help identify the etiology such as bicuspid aortic valve and associated problems such as dilated aortic root. – Generally, 2D echo alone can not adequately evaluate the severity of the Aortic Stenosis.

Question 19

Echo doppler use for Aortic stenosis?

Answer 19

– Continuous wave Doppler can assess the severity of Aortic Stenosis. Increased peak velocity =increased peak gradient Mean gradient can also be calculated. Modified Bernoulli equation: 4 Vmax2 = estimated peak gradient eg. 4 (4.0m/s) 2 = 64 mm Hg Continuity equation: AVA = cross sectional area LVOT x (V lvot/V ao) (equations not needed).

– In problem cases, transesophageal echo can be used to directly visualize the valve and, often, trace the valve area.

– Dobutamine echo with Doppler may be helpful in determining whether an apparent low valve gradient is simply secondary to low cardiac output in severe LV dysfunction (ie. mean gradient increases to greater than 30mm w/ dobutamine).

– In the vast majority of cases, echoDoppler is adequate for judging the severity of aortic stenosis and for making clinical decisions.*

Question 20

What is the definition of severe aortic stenosis?

Answer 20

• Mean gradient across aortic valve of > 40mm Hg • Peak velocity across aortic valve > 4m/sec (peak gradient > 64mm) • Aortic valve area < 1.0 cm2 • Aortic valve area < 0.6 cm2/m2

Question 21

explain the classifications of mild moderate and severe aortic stenosis with the mean gradient and the area of the valve?

Answer 21

Question 22

Cardiac Catheterization in aortic stenosis?

Answer 22

• In general, cardiac catheterization in aortic stenosis is used to determine the presence and extent of coronary artery disease prior to anticipated valve surgery.

– It is generally not necessary in young adults unless 2 or more risk factors for premature CAD are present.

– Patients 35 yrs and older should have coronary angiography prior to valve replacement.

– Occassionally, catheterization can help to clarify the significance of aortic stenosis when echo-doppler is not definitive. If there is an adequate echo, it is not necessary to subject the patient to the risk of crossing the valve.

Question 23

During the asymptomatic events how do we manage moderate to severe Aortic stenosis?

Answer 23

– Avoid strenuous exertion/competitive sports.

– Instruct patient regarding symptoms and need for prompt medical evaluation if present.

– Although historically felt to be contraindicated, if there is lack of clarity regarding the presence or absence of symptoms, a carefully performed exercise test may be helpful.

– Avoid negative ionotropes.

– Diuretics—use cautiously.

– Arterial dilators and venodilators (primarily nitrates)– use cautiously as they can lead to hypotension and syncope.

– Treat arrhythmias such as atrial fibrillation aggressively.

Question 24

Once you suspect severe aortic stenosis do what? Who should always be considered for surgery?

Answer 24

Once you suspect severe AS clinically, echo is generally used to confirm the diagnosis. If the patient is asymptomatic most physicians would continue to follow the patient closely. If the patient is symptomatic with severe AS, medical treatment is unsatisfactory. Therefore, all symptomatic patients with valve area < 1 cm2 should be considered for surgery (aortic valve replacement).

Question 25

Benefits of aortic valve replacement?

Answer 25

• Reduced mortality
• Reduced symptoms and increased functional status
• Improvement in LV systolic function
• Regression of left ventricular hypertrophy –Generally LVH will regress over months to years but may never entirely return to normal.

Question 26

When is aortic valve replacement clearly indicated?

Answer 26

1. AVR clearly indicated
   a. Symptomatic patients with severe AS
   b. Patients with severe AS undergoing CABG
   c. Patients with severe AS undergoing surgery on the aorta or other heart valves
   d. Patients with severe AS and LV dysfunction (EF<50%)*

Question 27

When is aortic valve replacement reasonable?

Answer 27

Patients with moderate AS undergoing surgery on the aorta , other heart valves or CABG.

• Asymptomatic patients with severe AS and abnormal response to exercise
• Asymptomatic pts if there is a high liklihood of rapid progression or if surgery might be delayed at symptom onset
• May be considered in pt with mild AS undergoing CABG when there is evidence such as heavy calcification that progression might be rapid.
• May be considered is asymptomatic pts with very severe AS (AVA<0.6, mean gradient >60)
• Select symptomatic patients with low flow/low gradient aortic stenosis with characteristic dobutamine response or for whom valve obstruction is the most likely source of symptoms despite the low gradient.

Question 28

Contraindications for aortic valve replacement in severe aortic stenosis?

Answer 28

• Because of the high mortality of severe, symptomatic aortic stenosis and the lack of effective medical therapy, AVR should be considered in all patients who are reasonable operative candidates.*

–Advanced age per se is not a contraindication to surgery.

–Depressed LV function is not a contraindication to surgery.

Question 29

What are alternative therapies to aortic vavle replacement?

Answer 29

• Aortic balloon valvuloplasty can be an effective treatment in children, adolescents and adults in their early 20s. – It is not effective in older adults. The average gain in valve area is 0.3cm2 and post procedure valve area averages 0.8 cm2. – It may have role as a ‘bridge’ to surgery; for palliation of patients with severe comorbid conditions; or for patients who require urgent noncardiac surgery. – In adult practice, it is rarely used.
• Percutaneous aortic valve replacement (TAVR) – Still in trials with high morbidity and mortality so far – Will probably be a viable alternative in the near future
• Medical therapy of heart failure in patients with severe AS who are not operative candidates (ie. malignancy or other serious comorbidity), would include digoxin, diuretics, ace-inhibitors, etc. Excessive preload or afterload reduction can lead to hypotension and possibly death. Caution is therefore advised.

Question 30

What is the follow-up of asymptomatic patient for aortic sclerosis and mild moderate and severe aortic stenosis?

Answer 30

– Patients with bicuspid aortic valves should be evaluated annually given a higher rate of aortic root dilitation/aneurysm*

– Aortic Sclerosis: ??

– Mild AS: every 1-2 yrs

– Moderate AS: every 12 months

– Severe AS: at least every 6 months • Immediate follow-up if symptoms

Question 31

Therapy of mild aortic stenosis and aortic sclerosis?

Answer 31

• Encourage normal life
• Instruct in symptoms
• Consider aggressive atherosclerotic risk factor modification*