Page created on April 9, 2022. Not updated since.

Aortic stenosis

Introduction and epidemiology

Aortic stenosis (AS) refers to narrowing of the aortic valve, resulting in increased pressure load on the left ventricle. AS is mostly a disorder of the elderly (>70 years) men, and it’s the most common valvular disease. Some also have some degree of aortic regurgitation.

Etiology

In most cases, aortic stenosis is a result of dystrophic calcification and degeneration of the aortic valve with age. 1 – 2% of the population have a congenital bicuspid aortic valve, which predisposes to aortic stenosis and causes it to occur at younger ages (<70 years).

In developing countries, rheumatic fever remains a significant cause.

Clinical features

Patients usually progress from asymptomatic to symptoms during exertion to symptoms in rest. Symptoms only occur when the stenosis is severe. The most common symptom is dyspnoea and exercise intolerance, but other symptoms include angina and syncope.

A systolic crescendo-decrescendo ejection murmur is typical. It’s best heard at the punctum maximum of the aortic valve, parasternally in the 2^nd right intercostal space. It may radiate to the carotids. Soft S2 is also a typical finding.

Diagnosis and evaluation

Echocardiography allows for assessment of the aortic valve opening area and the pressure gradient and velocity across the valve, which is increased in case of stenosis. Coronary angiography can be used to assess the degree of coronary artery disease.

Treatment

In mild cases, regular follow-up alone might be sufficient, but the only definitive treatment is valvular replacement. This can be achieved by open surgery (surgical aortic valve replacement, SAVR) or transcatheter replacement (transcatheter aortic valve replacement, TAVR). If significant CAD is present, coronary bypass can be performed in the same setting as the surgical replacement of the valve.

Complications

• Left ventricular hypertrophy -> heart failure
• Sudden cardiac death

Mitral regurgitation

Introduction and epidemiology

Mitral regurgitation (MR) refers to when the mitral valve closes incompletely during systole, causing blood to flow back from the left ventricle into the left atrium. It’s a common valvular heart disease.

MR can be primary, due to direct involvement of the valve itself or the chorda tendinae, or secondary, due to changes in the dimensions of the left ventricle, making it impossible for the anatomically normal mitral valve to close properly. It can also be either acute or chronic.

In acute MR, increased left ventricular end-diastolic volume causes backward congestion, causing pulmonary congestion or oedema.

In chronic MR, the heart compensates the increased LV end-diastolic volume by eccentric hypertrophy, dilating the chamber. However, over time, this compensatory mechanism leads to myocardial dysfunction and too large chamber, leading to heart failure.

Etiology

• Primary
  • Idiopathic degeneration of the mitral valve
  • Endocarditis
  • Rheumatic fever
• Secondary
  • Dilated cardiomyopathy
  • Coronary heart disease (ischaemia of the papillary muscles)

Clinical features

In acute MR, acute dyspnoea develops. In chronic MR, chronic heart failure develops. In case of acute MR, no murmur is typical, but in chronic MR there’s a holosystolic murmur with a “blowing” characteristic at the site of the apex. This murmur radiates to the left axilla.

Atrial fibrillation is common in chronic MR.

Diagnosis and evaluation

Echocardiography allows for assessment of the mitral valve motion during systole, and it can visualise regurgitated blood flow. Coronary angiography can be used to assess the degree of coronary artery disease.

Treatment

Surgery, either valve repair or replacement, is the definitive treatment for MR. In case of acute primary MR, urgent surgery is indicated. In case of chronic primary MR, surgery is indicated if the LVEF is decreased or the patient is symptomatic. However, if the LVEF is severely decreased (<30%), surgery is not recommended due to high mortality rate and low likelihood of improvement.

While waiting for surgery, pharmacological therapy for heart failure is required.

Aortic regurgitation

Introduction and epidemiology

Aortic regurgitation refers to when the aortic valve closes incompletely during systole, causing blood to flow back from the ascending aorta into the left ventricle. It’s a rare valvular disease.

Like MR, aortic regurgitation can be primary, due to direct involvement of the valve itself, or secondary, due to dilation of the ascending aorta, making it impossible for the anatomically normal aortic valve to close properly. It can also be either acute or chronic.

Etiology

• Primary
  • Infective endocarditis
  • Aortic dissection affecting the ascending aorta
  • Congenital bicuspid aortic valve (mostly younger adults)
  • Calcific aortic valve disease (mostly older adults, coexists with aortic stenosis)
• Secondary
  • Connective tissue disorders

Clinical features

Acute aortic regurgitation causes sudden severe dyspnoea due to acute heart failure and pulmonary oedema. Chronic aortic regurgitation progresses slowly from asymptomatic to heart failure.

Treatment

Surgery is the definitive treatment for both acute and chronic aortic regurgitation.