Aortic Regurgitation (AR)

Aortic Regurgitation is a valvular lesion in which the aortic valve fails to close completely during diastole, causing backward flow of blood from the aorta into the left ventricle (LV).

Normal Physiology

During diastole:

• Aortic valve closes
• Aortic pressure > LV pressure
• Coronary perfusion occurs

In AR:

• Blood leaks back into LV during diastole
• LV receives:
• Normal pulmonary venous return
• PLUS regurgitant volume

Result:

• Increased LVEDV
• Increased stroke volume
• Wide pulse pressure

Etiology

Acute Aortic Regurgitation

Life-threatening as LV has no time to adapt.

Chronic Aortic Regurgitation

Most common form.

Valve Leaflet Causes

Aortic Root Causes

Pathophysiology

• Acute AR Pathophysiology

No adaptive LV dilation.Small stiff LV suddenly receives large regurgitant volume.

Results:

• Massive LVEDP rise
• Pulmonary edema
• Cardiogenic shock
• Hypotension

Unlike chronic AR:Pulse pressure may NOT be wide.

Chronic AR

Initial Compensation

LV adapts by:

• Eccentric hypertrophy
• Increased compliance
• Increased chamber size

This allows:

• Large stroke volume
• Near-normal filling pressures

Patients may remain asymptomatic for years.

Progressive Disease

As regurgitation worsens:

LV Changes

• LV dilation
• Increased wall stress
• Fibrosis
• Reduced contractility

Hemodynamic Changes

• Increased LVEDP
• Pulmonary congestion
• Reduced forward cardiac output

Eventually:

• Heart failure
• Arrhythmias
• Sudden death

Hallmark-Wide pulse pressure.

Example: BP 170/50 mmHg

Why?

Increased systolic BP

Due to:Increased stroke volume

Reduced diastolic BP

Due to:Rapid runoff back into LV

Comparison: Acute vs Chronic AR

Peripheral Signs of Severe AR

These occur due to hyperdynamic circulation and wide pulse pressure.

Symptoms

Acute AR Symptoms

Severe and sudden.

Chronic AR

Long asymptomatic phase.

Symptoms When Compensation Fails

Physical Examination

• Pulse-Collapsing pulse (water hammer pulse).Mechanism:Rapid upstroke and Rapid collapse
• Blood Pressure-Wide pulse pressure.
• Apex Beat-Displaced downward and laterally–Hyperdynamic–Diffuse

• Murmur  –High-pitched blowing early diastolic decrescendo murmur(Mechanism-Regurgitant flow during diastole)

Best heard:

• Left sternal border
• 3rd–4th intercostal space
• Patient sitting forward
• End expiration

Austin Flint Murmur-Low-pitched mid-diastolic rumble at apex.

Mechanism:

• Regurgitant jet strikes anterior mitral leaflet
• Functional mitral stenosis

Indicates severe AR.

Acute AR Examination

May have:

• Soft/short murmur
• No peripheral signs
• Severe pulmonary edema
• Shock

Severity Assessment by Clinical Clues

Investigations

ECG

May show:

• LV hypertrophy
• Left axis deviation
• Strain pattern

Acute AR may show nonspecific changes.

Chest X-ray

Chronic AR:

• Cardiomegaly
• LV enlargement
• Dilated ascending aorta

Acute AR:Pulmonary edema

Echocardiography — MOST IMPORTANT

• Color Doppler-Regurgitant jet into LVOT.
• CW Doppler-Dense diastolic jet.

Transesophageal Echo (TEE)

Useful in:

• Endocarditis
• Acute AR
• Aortic dissection
• Intraoperative assessment

CT / MRI

Useful for:

• Aortic root disease
• Aneurysm
• Dissection
• Quantification when echo unclear

Cardiac Catheterization

Rarely needed now.

Used before surgery if:

• CAD suspected
• Echo inconclusive

Classification of Severity

Differential Diagnosis

Complications

Management

• Acute Severe AR-MEDICAL EMERGENCY.
• Stabilization
• Oxygen and Ventilation
• Vasodilators(Nitroprusside)

• Reduces afterload
• Improves forward flow

Inotropes-Dobutamine if shock

Avoid

Why IABP is Contraindicated

Regurgitant Volume∝Diastolic Aortic Pressure×Diastolic Time

IABP inflates during diastole.

This:Raises aortic diastolic pressure/Increases regurgitant flow

Therefore:Worsens AR

Hemodynamic Goals in Severe AR (ICU)

Definitive Treatment

Emergency surgery.Especially for:

• Dissection
• Endocarditis
• Acute valve destruction

Chronic AR Management

Medical Therapy

Vasodilators

Useful especially if:

• Hypertension
• Not surgical candidate

Drugs:

• ACE inhibitors
• ARBs
• Nifedipine

Role of Beta Blockers

Generally limited in isolated severe AR because:

• Slower HR increases diastolic regurgitation time

However beneficial in:

• Marfan syndrome
• Aortic aneurysm disease

Indications for Surgery

Symptomatic Severe AR

AVR indicated regardless of EF.

Asymptomatic Severe AR

Operate if:

• LVEF ≤55%
• LVESD >50 mm
• LVESD index >25 mm/m²
• Progressive LV dilation
• Undergoing other cardiac surgery

Surgery Types

Surgical Aortic Valve Replacement (SAVR)

Standard treatment.

Mechanical Valve

Pros:Durable

Cons:Lifelong anticoagulation

Bioprosthetic Valve

Pros:No long-term anticoagulation

Cons:Structural degeneration

Valve Repair

Possible in selected:Root dilation/Bicuspid valve

TAVR in AR

Less established than in AS.

Used selectively.

Aortic Root Surgery

Needed if:

• Aneurysm
• Marfan syndrome
• Root dilation

Examples:

• Bentall procedure
• Valve-sparing root replacement

Follow-Up

Pregnancy and AR

Chronic AR usually tolerated due to:

• Reduced SVR in pregnancy

Poor prognostic factors:

• Severe LV dysfunction
• Marfan syndrome with aortic root dilation