Learning objectives

• Describe and classify mitral regurgitation
• Describe the causes and mechanisms of mitral regurgitation
• Manage patients with mitral regurgitation

Definition & mechanisms

• Mitral regurgitation (MR) can be acute or chronic in onset, and primary or secondary in nature
• Primary MR is due to pathology of the valve preventing normal closure 
• Secondary MR is caused by left ventricle dysfunction that affects the closing of the mitral valve 
• The left atrium dilates as blood is ejected back into it
• Atrial fibrillation is common
• Overload of the pulmonary circulation causes dyspnea
• The LV is volume overloaded in, with dilation of the ventricle further worsening MR 
• Acute MR:
  • Can be caused by any disruption to the normal mechanism of the valve (growth of vegetations on the leaflets in infective endocarditis, chordae rupture in patients with pre-existing degenerative disease, or papillary muscle rupture due to an ST-elevation)
  • The left atrium is unable to compensate acutely for the increased pressure caused by blood refluxing back into it
  • Patients can present with sudden-onset dyspnea and require rapid stabilization and treatment
• Chronic MR:
  • Primary: Abnormality of the leaflets that prevents them from closing normally
  • Secondary:  Anatomy of the valve is normal, but its function is impaired due to left ventricle pathology

Classification

Transoesophageal echocardiography remains the gold standard for defining the severity of the MR:

Treatment

• Medical
  • Acute MR: Filling pressure reduction with nitrates or diuretics and afterload reduction with vasodilators or an intra-aortic balloon pump as bridging to definitive treatment
  • Chronic MR: Treatment is in line with standard heart failure management including β-blockers, angiotensin-converting enzyme inhibitors, and aldosterone antagonists, with diuretics where heart failure is present
• Surgical
  • Primary MR:  
    • Surgery is indicated if the MR is severe and acute in nature and if the MR is chronic and causing symptoms, with no contraindications to surgery
    • Valve repair, rather than replacement, is preferred
  • Secondary MR: 
    • In symptomatic patients with severe left ventricle failure, the benefits of surgery are controversial unless the underlying condition can be reversed

Anesthetic management

Suggested reading

• Holmes K, Gibbison B, Vohra HA. Mitral valve and mitral valve disease. BJA Education. 2017;17(1):1-9.