Mitral Incompetence Overview

Mitral Incompetence (Mitral Regurgitation)

• Mitral regurgitation (MR) is a type of valvular heart disease. The mitral valve doesn't close properly, causing blood to leak backward.
• Blood leaks back into the left atrium from the left ventricle during contraction.
• MR is the most common form of valvular heart disease.

Causes of Mitral Incompetence

• Rheumatic heart disease: Fibrosis and retraction of the valve cusps.
• Congenital: Present from birth.
• Functional: Due to left ventricular dilation.
• Surgical: Following mitral commissurotomy or prosthetic valve dysfunction.
• Mitral valve prolapse: Issues with the valve structure.
• Papillary muscle dysfunction: Problems with the muscles supporting the valve, e.g., ischemic heart disease or cardiomyopathy.

Hemodynamics of Mitral Incompetence

• Left atrial dilatation: The left atrium expands to accommodate the increased blood volume it receives from the left ventricle during systole (contraction phase).
• No immediate pulmonary congestion: Compensated MR doesn't immediately cause pulmonary congestion.
• Systolic pulsations: Blood flow through the left atrium causes pulsations/stirring. Thromboembolism is less common in compensated mitral incompetence compared to mitral stenosis.

Left Ventricular Dilation

• Left ventricle dilates to accommodate increased blood volume.
• Hypertrophy occurs to maintain contractility.
• Long-standing cases can lead to left ventricular failure and a vicious cycle of progressive mitral regurgitation.
• Onset of heart failure is associated with rising end-diastolic pressures, and pulmonary venous pressure.

Eccentric vs. Concentric Hypertrophy

• Eccentric hypertrophy: Characterized by chamber dilation, but cardiomyocyte size generally increases.
• Concentric hypertrophy: Characterized by wall thickening.

Symptoms During Systole and Diastole

• Systole: Blood regurgitates to the left atrium, causing low cardiac output and left atrial dilation.
• Diastole: Excessive blood volume now enters the left ventricle, leading to potential enlargement and left ventricular failure.

Compensated Mitral Incompetence

• Slow development over months to years.
• Left ventricle adapts with eccentric hypertrophy, allowing normal forward cardiac output.
• Pulmonary congestion decreases due to improved left atrial drainage.
• Individuals often asymptomatic or have normal exercise tolerance.

Decompensated Mitral Incompetence

• The left ventricle loses the ability to compensate with adequate contraction.
• Forward cardiac output declines, and end-systolic volume increases.
• Increased filling pressures and pulmonary congestion leads to symptoms of congestive heart failure.
• Left ventricle dilation worsens regurgitation.

Clinical Manifestations

• Compensated: Asymptomatic or non-specific symptoms like palpitations or fatigue.
• Decompensated: Symptoms of heart failure (dyspnea, hemoptysis, recurrent bronchopulmonary infections), fatigue.

Complications

• Left ventricular failure: A major complication.
• Infective endocarditis: Possible due to inflammation and abnormal growths on the valve.

Clinical Manifestations (Mild Cases)

• Absence of noticeable symptoms
• Mild cardiac output symptoms (Fatigue, confusion, low blood pressure)
• Pulmonary congestion symptoms (Orthopnea, cough, haemoptysis)

Diagnostic Methods

• ECG: Can show left atrial and left ventricular enlargement.
• Chest X-ray: Shows chamber enlargement and pulmonary congestion if left ventricular failure is present.
• Echocardiography: Diagnoses mitral incompetence, assesses severity, and detects associated lesions.
• Cardiac catheterization & angiography: Invasive procedure. Useful for diagnosing mitral incompetence, assessing the severity, associated lesions, chamber enlargement, and detection of coronary artery disease.

Treatment

• Medical: Prophylaxis against infective endocarditis, treating heart failure/arrhythmias, embolisms, and rheumatic activity.
• Surgical: Mitral valve repair (preferred), replacement if repair isn't feasible.

Surgical Indications

• Marked symptoms unresponsive to medical treatment
• Progressive cardiomegaly
• Decreasing left ventricular function (ejection fraction).

Points of Comparison (Mitral Stenosis vs. Mitral Incompetence)

• Differences in presentation, symptoms, and the timing of congestion and other symptoms and patterns.

Explore the essential aspects of mitral incompetence, including its causes, effects on hemodynamics, and implications for patients. This quiz covers types of mitral regurgitation, and how it impacts heart function. Test your knowledge on this common valvular heart disease.