Forth stage / Medicine / Lec-5
د.جاسم محمد / 9/11/2015

Aortic Stenosis

Overview:

•Normal Aortic Valve Area: 3-4 cm2

•Symptoms:Occur when valve area is 1/4th of normal area.

•Types:

Supravalvular

Subvalvular

Valvular

Etiology of Aortic Stenosis

•Congenital (Bi-cusped).

•Rheumatic.

•Degenerative/Calcific.

Patients under 70: >50% have a congenital cause

Patients over 70: 50% due to degenerative

Evaluation of AS:

Cardiac catheterization:Should only be done for a direct measurement if symptom severity and echo severity don’t match OR prior to replacement when replacement is planned.

Pathophysiology of Aortic Stenosis

  • A pressure gradient develops between the left ventricle and the aorta. (Increased afterload)
  • LV function initially maintained by compensatory pressure hypertrophy

to maintain the cardiac output

  • When compensatory mechanisms exhausted, LV function declines and pulm.edema supervenes.

Presentation of Aortic Stenosis:

  1. Asymptomatic mild/moderate
  2. Syncope: (exertional)
  3. Angina: (increased myocardial oxygen demand; demand/supply mismatch)
  4. Dyspnea: on exertion due to heart failure (systolic and diastolic)
  5. Sudden death

Physical Findings in Aortic Stenosis

  • Slow rising carotid pulse (pulsus tardus)
  • Thrusting apex beat (LV pressure overload)
  • Narrow pulse pressure
  • Heart sounds- soft and split second heart sound, S4 gallop due to LVH.
  • Systolic ejection murmur- cresendo-decrescendo character. Thispeaks later as the severity of the stenosis increases.
  • Loudness does NOT tell you anything about severity

Investigations

  • ECG Left ventricular hypertrophy ,LBBB
  • Chest X-ray May be normal; sometimes enlarged LV and dilated ascending aorta on PA view, calcified valve on lateral view.
  • Echo Calcified valve with restricted opening, hypertrophied LV) Doppler Measurement of severity of stenosis Detection of associated aortic regurgitation.
  • Cardiac catheterization Mainly to identify associated coronary artery disease May be used to measure gradient between LV and aorta.

Management of AS

  • General- IE prophylaxis in dental procedures with a prosthetic AV or history of endocarditis.
  • Medical - limited role since AS is a mechanical problem. Vasodilators are relatively contraindicated in severe AS
  • Aortic Balloon Valvotomy- shows little benefit.
  • Surgical Replacement: Definitive treatment

Simplified Indications for Surgery in Aortic Stenosis

  • Any SYMPTOMATIC patient with severe AS (includes symptoms with exercise)
  • Any patient with decreasing EF
  • Any patient undergoing CABG with moderate or severe AS

Aortic Regurgitation

Overview:

Definition:Leakage of blood into LV during diastole due to ineffective coaptation of the aortic cusps.

Etiology of Acute AR

  • Endocarditis
  • Aortic Dissection

Physical Findings:

  • Wide pulse pressure
  • Diastolic murmur
  • Florid pulmonary edema

Treatment of Acute AR

  • True Surgical Emergency:
  • Positive inotrope: (e.g., dopamine, dobutamine)
  • Vasodilators: (e.g., nitroprusside)
  • Avoid beta-blockers
  • Do not even consider a balloon pump

Etiology of Chronic AR

  • Cusps defects
  • Congenital -Bicuspid aortic valve
  • Rheumatic
  • Infective endocarditis
  • Aortic root dilatation Marfan.

Pathophysiology of AR

  • Combined pressure AND volume overload
  • Compensatory Mechanisms: LV dilation, LVH. Progressive dilation leads to heart failure.

Symptoms

  • Asymptomatic until 4th or 5th decade
  • Progressive Symptoms include:
  • Dyspnea: exertional, orthopnea, and paroxysmal nocturnal dyspnea
  • Nocturnal angina: due to slowing of heart rate and reduction of diastolic blood pressure.
  • Palpitations: due to increased force of contraction.

Signs

Peripheral signs

•Pulses Large volume or ‘collapsing’ pulse.

•Corrigan pulse

•Increased pulse pressure

•Bounding peripheral pulses

•Capillary pulsation in nail beds: Quincke’s sign Femoral bruit (‘pistol shot’)

•Duroziez’s sign

•Head nodding with pulse: de Musset’s sign.

•Hill’s sign

•JVP may be normal or elevated

Central Signs

•Apex: Hyperdynamic and displaced apical impulse.

•Diastolic thrill.

Auscultation

•High pitched, blowing, decrescendo diastolic murmur at LSB, best heard at end-expiration & leaning forward.

•Austin-Flint murmur indicates severity (mid to late diastolic murmur)

•Systolic murmur related to high flow state

Investigations

•ECG Initially normal, later left ventricular hypertrophy and T-wave inversion

•Chest X-ray Cardiac dilatation, maybe aortic dilatation Features of left heart failure

•Echo Dilated LV Hyperdynamic, LV Doppler detects reflux , Fluttering anterior mitral leaflet

•Cardiac catheterization (may not be required) , Dilated LV , Aortic regurgitation , Dilated aortic root.

Management of AR

•General: IE prophylaxis in dental procedures with a prosthetic AV or history of endocarditis.

•Medical: Vasodilators (ACEI’s), Nifedipine improve stroke volume and reduce regurgitation only if pt. symptomatic or HTN.

•Serial Echocardiograms: to monitor progression.

•Surgical Treatment: Definitive Rx

Simplified Indications for Surgical Treatment of AR

•ANY Symptoms at rest or exercise

•Asymptomatic treatment if:

•EF drops below 50% or LV becomes dilated.

Tricuspid stenosis

Almost always rheumatic

•The low cardiac output state causes fatigue; abdominal discomfort may occur due to hepatomegaly and ascites

•The diastolic murmur of tricuspid stenosis is augmented by inspiration.

•Medical management includes salt restriction and diuretics.

• Surgical treatment in patients with a valve area <2.0cm and a mean pressure gradient >5mmHg.

Tricuspid regurgitation

•Most common cause is annular dilatation due to RV failure of any cause

•Symptoms and signs result from a reduced cardiac output, ascites, painful congestive hepatomegaly and oedema.

•The pansystolic murmur of TR is usually loudest at the left sternal edge and augmented by deep inspiration.

•Severe functional TR may be treated by annuloplasty or valve replacement. Severe TR due to intrinsic tricuspid valve disease requires valve replacement.

Pulmonary stenosis

Most commonly due to congenital malformation

•Survival into adulthood is the rule, infective endocarditis is a risk and right ventricular failure is the most common cause of death.

• Carcinoid plaques may lead to constriction of the pulmonary valve ring.

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