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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

aortic regurgitation, echocardiography, ecg, x-ray, apex, pulse, murmur, diastolic, austin-fint, de musset, corrigan, blood pressure, heart rate, sinus rhythm, dysrhythmias, preload, afterload, arterial pressure, transesophageal, neuraxial, analgesia, catecholamine, hypertension, icu

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

Suggested reading

  • Flint N, Wunderlich NC, Shmueli H, Ben-Zekry S, Siegel RJ, Beigel R. Aortic Regurgitation. Curr Cardiol Rep. 2019;21(7):65. 
  • Pollard BJ, Kitchen, G. Handbook of Clinical Anaesthesia. Fourth Edition. CRC Press. 2018. 978-1-4987-6289-2.
  • Hines, R. L. (2017). Stoelting’s anesthesia and co-existing disease (7th ed.). Elsevier – Health Sciences Division
  • Nishimura RA, Otto CM, Bonow RO, et al. 2014 AHA/ACC Guideline for the Management of Patients With Valvular Heart Disease: executive summary: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines [published correction appears in Circulation. 2014 Jun 10;129(23):e650]. Circulation. 2014;129(23):2440-2492.

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