Aortic Valve Anatomy and Pathology Quiz

Aortic Valve Anatomy

• Three cusps attached to the proximal aorta (aortic root)
• No subvalvular apparatus
• Opens during systole (ejection phase) allowing blood flow from the left ventricle to the aorta
• Closes during diastole (producing S2) to prevent backward flow from the aorta to the left ventricle

Aortic Valve Pathology

• Stenosis: narrowing of the aortic valve opening
• Regurgitation: backward flow of blood from the aorta to the left ventricle due to improper closure of aortic valve cusps or failure of cusps coaptation during diastole

Aortic Stenosis

• Classification
  • Valvular AS: Narrowing of the aortic valve opening
  • Subvalvular AS: Stenosis below the aortic valve in the left ventricular outflow tract (membrane or ridge)
  • Supravalvular AS: Stenosis above the aortic valve in the aorta (narrowing in the ascending aorta)
• Causes
  • Congenital: Bicuspid aortic valve, Subvalvular AS, Supravalvular AS
  • Degenerative: Old age, Western countries
  • Rheumatic: Young age, Developing countries
• Pathology
  • Thickening, fibrosis, calcification of the valve causing narrowing of the opening
• Pathophysiology
  • Progressive aortic valve narrowing leads to progressive left ventricular hypertrophy (LVH), increased left ventricular systolic pressure with increased myocardial oxygen demand, this leads to myocardial ischemia and left ventricular failure (pulmonary congestion)

Aortic Stenosis Presentation

• History
  • Typically asymptomatic until valvular stenosis is severe
  • The hallmark of AS is the classical triad of exertional dyspnea, angina, and syncope (or near-syncope)
    • Exertional dyspnea is the most common symptom associated with severe AS
    • Angina without significant obstructive coronary artery disease is caused by subendocardial ischemia due to increased total oxygen demand secondary to LVH
    • Exertional syncope (or near syncope) occurs due to diminished cerebral perfusion secondary to low cardiac output
    • Symptoms may not develop simultaneously, only one of the three may be present
• Physical Examination
  • Hallmarks of severe AS on physical examination include:
    • Pulse: Reduction in the amplitude and delay of the carotid upstrokes (“parvus et tardus”).
    • Apical impulse: Shifted downwards, outwards, heaving character, localized (LV apex).
  • Cardiac auscultation
    • Diminution or entire loss of the second heart sound (↓S2)
    • An opening ejection click in patients with a bicuspid valve
    • Ejection systolic crescendo-decrescendo murmur (radiates to the carotids, sometimes associated with a thrill. Radiation may also occur across the precordium and to the apex (Gallavardin phenomenon) associated with a musical, high frequency quality)
• Investigations
  • Echocardiography: Assess severity of AS, LV function
  • CXR: Lung congestion
  • ECG: LVH

Aortic Stenosis Treatment

• Prophylaxis against infective endocarditis, secondary prevention of rheumatic activity
• Medical: Diuretics for HF symptoms
• Interventional: Transcatheter aortic valve implantation (TAVI)
• Surgical: Aortic valve replacement either by mechanical or tissue prosthesis

Aortic Regurgitation

• Presentation
  • Acute AR: Presented with acute pulmonary edema, or cardiogenic shock

Chronic Aortic Regurgitation

• History
  • Symptoms are related to exaggerated cardiac output with increased stroke volume, including a sense of pounding in the chest
    • Palpitations
    • Dyspnea
    • Chest pain
• Physical Examination
  • Blood pressure: High systolic BP, Low DBP, Wide pulse pressure
  • Pulse:
    • Water hammer: Characterized by exaggerated upstroke and fall of the arterial pulse, notable in the carotid pulse.
  • Apical impulse: Shifted downwards, outwards, hyperdynamic character (LV apex)
  • Cardiac auscultation
    • Diminution of the second heart sound (↓S2) with thickened calcific valve and accentuated S2 with dilated aortic root
    • The murmur of AR:
      • High-pitched (“blowing”) in quality.
      • Radiation: Along the left sternal border and is best heard with the patient sitting up and leaning forward after full expiration. If the murmur radiates along the right sternal border, it is suggestive of a dilated aortic root.
    • Ejection systolic murmur (Functional AS; caused by ↑ systolic forward flow).
    • Very significant AR may be accompanied by a low pitched late mitral diastolic rumble (= MS; the “Austin-Flint” murmur) due to improper opening of the mitral valve by the aortic regurgitant jet.
• Investigations
  • Echocardiography: Assess severity of AR, LV function, define the cause of AR
  • CXR: Lung congestion

Aortic Regurgitation Treatment

• Prophylaxis against infective endocarditis, secondary prevention of rheumatic activity
• Medical: Diuretics for HF symptoms, Dilators. Good blood pressure control (afterload reduction) with calcium channel blockers and vasodilators (ACE inhibitors)
• Surgical:
  • For Acute AR: Treat the cause, hemodynamic support, AV replacement
  • For Chronic AR:
    • AV replacement (mechanical or biological prosthesis) ± Aortic root replacement
    • AV repair