Makindo Medical Notes

Related Subjects: |Aortic Anatomy |Acute Coronary Syndrome (ACS) General |Aortic Dissection |Acute Heart Failure and Pulmonary Oedema |Aortic Regurgitation (Incompetence) |Aortic Stenosis |Aortic Sclerosis |Transcatheter aortic valve implantation (TAVI)

About

• Aortic Regurgitation (Incompetence): A condition where, at the end of systole, blood ejected into the aorta flows back into the left ventricle (LV) during diastole due to the failure of the aortic valve to close properly.
• This backward flow leads to a volume overload in the LV, causing it to dilate and hypertrophy over time as a compensatory mechanism.
• Chronic AR may progress over years, while acute AR can cause rapid heart failure and require urgent intervention.

Anatomy

• The aortic valve has three leaflets, each with a cusp or cup-like configuration: left coronary cusp (L), right coronary cusp (R), and posterior non-coronary cusp (N).
• Above the aortic valve are the sinuses of Valsalva, which are anatomical dilations in the ascending aorta that support blood flow into the coronary arteries.
• Proper closure of the valve leaflets prevents backflow of blood into the LV during diastole.

Aetiology

• AR results from conditions that affect the valve leaflets or the aortic root, leading to improper closure and regurgitation.
• Volume overload of the LV occurs as blood regurgitates back during diastole, leading to compensatory LV dilation and hypertrophy.
• The regurgitant jet can impair coronary perfusion, especially in severe cases, contributing to angina symptoms even in the absence of coronary artery disease.

Causes

Clinical Features

• Acute AR: Presents with sudden onset of severe dyspnoea, chest pain, and cardiogenic shock. Acute pulmonary edema is common, with symptoms like tachycardia, raised JVP, and basal crackles.
• Chronic AR: Often asymptomatic for years, followed by exertional dyspnoea, orthopnoea, palpitations, and signs of heart failure as LV function deteriorates.
• Signs include a high-pitched, early diastolic murmur at the left sternal edge, best heard with the patient sitting forward and holding breath in expiration.
• Wide pulse pressure with a "water hammer" pulse due to increased stroke volume and rapid diastolic runoff.

Eponymous Signs

• Austin Flint Murmur: A mid-diastolic rumbling sound caused by the regurgitant jet hitting the anterior mitral leaflet.
• Quincke's Sign: Visible capillary pulsations in the nail beds.
• Corrigan's Pulse: A bounding pulse with a rapid upstroke and quick collapse, also called "water hammer pulse."
• De Musset's Sign: Head bobbing with each heartbeat.
• Traube's Sign: "Pistol-shot" sounds heard over the femoral arteries.

Investigations

• Blood Tests: FBC, CRP, and blood cultures if infective endocarditis is suspected. Monitor renal function and electrolytes.
• CXR: May show cardiomegaly, evidence of LV dilation, and a dilated ascending aorta.
• ECG: Left ventricular hypertrophy (LVH) with strain pattern is common in chronic AR. May show conduction abnormalities or signs of ischaemia.
• Echocardiography: The key diagnostic tool to assess valve morphology, regurgitation severity, LV size, function, and aortic root diameter. TTE or TEE may be used for more detailed evaluation.
• Cardiac MRI: Provides detailed imaging of the aorta and LV function, useful for assessing the aortic root and valve anatomy.
• Cardiac Catheterization: May be used pre-surgery to assess coronary arteries and confirm hemodynamic measurements in cases where echocardiographic findings are inconclusive.

Complications

• Heart Failure: Due to progressive LV dilation and systolic dysfunction.
• Acute Pulmonary Edema: Common in acute AR due to sudden volume overload.
• Infective Endocarditis: Due to the turbulent flow across the damaged valve.
• Aortic Aneurysm: Progressive aortic dilation can lead to aneurysm formation, increasing the risk of rupture.
• Sudden Cardiac Death: Due to severe LV dysfunction or arrhythmias in advanced disease.

Management

Indications for Surgery

• Symptomatic patients with severe AR regardless of LV function.
• Asymptomatic patients with severe AR and LVEF <50%.
• Severe AR with significant LV dilation (end-systolic dimension ≥50 mm or end-diastolic dimension ≥70 mm).
• Aortic root dilation >50 mm in patients with Marfan syndrome or other connective tissue disorders.

Prognosis

• Prognosis depends on the severity of AR, LV function, and the timing of surgical intervention.
• Asymptomatic patients with preserved LV function have a good prognosis with appropriate monitoring and medical therapy.
• Delayed surgical intervention in symptomatic patients with LV dysfunction is associated with increased mortality.

References

• 2017 ESC/EACTS Guidelines for the Management of Valvular Heart Disease
• AHA/ACC Guidelines for the Management of Patients with Valvular Heart Disease
• Otto CM, et al. "Aortic Regurgitation and Its Management." New England Journal of Medicine. 2020; 382:1621-1632.