Aortic regurgitation (AR)

Learning objectives

Describe the underlying mechanisms of AR
Recognize the symptoms of AR
Manage patients with AR

Definition & mechanisms

Aortic regurgitation (AR) is defined as diastolic reversal of blood flow from the aorta into the left ventricle
Most common etiology: Atherosclerotic degeneration of the valve, especially in the presence of a bicuspid aortic valve
Acute AR:
- May develop from:
  - Valvular abnormalities (most commonly infective endocarditis)
  - Aortic abnormalities (mostly aortic dissection)
  - Iatrogenic causes such as traumatic injury (i.e., motor vehicle accident) or during transcutaneous aortic valve procedures
- Characterized by an abrupt increase in left ventricular end-diastolic volume
- In severe cases, patients often present with pulmonary edema and even cardiogenic shock
Chronic AR:
- Most commonly caused by atherosclerotic degeneration of the valve and/or congenital bicuspid aortic valve
- In the early phases, compensatory mechanisms keep the left ventricular ejection fraction in the normal range
- Over time, the LV dilates and hypertrophies to normalize wall stress by maintaining the ratio of ventricular wall thickness to cavity radius
- Compensatory mechanisms allow patients to remain stable and asymptomatic for many years, even in the presence of severe AR
- If wall thickening fails to keep up with the volume overload, there is an increase in wall stress which then results in a reduction in LV systolic function and LVEF due to myocyte damage
- As LV filling pressures rise, symptoms of fatigue and dyspnea may appear
- Angina can develop even in the presence of normal coronary arteries
- Pulmonary edema and heart failure can occur due to chronically elevated left-sided filling pressures

Signs & symptoms

Symptoms
- Chronic AR
  - Patients with chronic AR remain asymptomatic for years. When symptoms appear, they are due to left heart failure:
    - Chest pain
    - Increasing exercise intolerance
    - Dyspnea
    - Paroxysmal nocturnal dyspnea
    - Orthopnea
- Acute AR
  - Because of a lack of chronic compensation, patients usually present with pulmonary edema and heart failure refractory to optimal medical therapy
  - Patients are often hypotensive and clinically appear to be on the verge of cardiovascular collapse
Diagnostic signs
- Collapsing pulse and wide pulse pressure
- Displaced apex inferolaterally
- Early diastolic high-pitched murmur
- An Austin-Flint murmur may be heard in mid-diastole at the apex
- De Musset’s sign – Head nodding with each pulse
- Corrigan’s sign – Visible carotid pulsation

Severity assessment

Echocardiography is the best diagnostic tool to evaluate the severity of AR. A rough guideline for approximating severity is the width of the AR jet compared to the width of the left ventricular outflow tract:
- <1/3: Mild
- 1/3–2/3: Moderate
- >2/3: Severe

Management

Acute severe AR management

Sudden aortic incompetence results in acute pulmonary congestion
Immediate management:
- Afterload reduction (nitroprusside)
- Enhancement of contractility and heart rate (dobutamine)
- Emergency surgical intervention is likely necessary
- Intra-aortic balloon pump is contraindicated

Table of Contents

Contributors

Aortic regurgitation (AR)

Aortic regurgitation (AR)

Learning objectives

Definition & mechanisms

Signs & symptoms

Severity assessment

Management

Acute severe AR management

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