Table of Contents
- Definition of Mitral Insufficiency
- Epidemiology of Mitral Insufficiency
- Etiology of Mitral Insufficiency
- Classification of Mitral Insufficiency
- Pathophysiology of Mitral Insufficiency
- Symptoms and Clinical Presentation of Mitral Insufficiency
- Progression and Special Types of Mitral Insufficiency
- Diagnosis of Mitral Insufficiency
- Treatment of Mitral Insufficiency
- Complications of Mitral Insufficiency
Mitral valve insufficiency is the second most common disease of the heart valves. It has various causes but is associated with a favorable prognosis, especially because it can remain asymptomatic for a long time. Good adaptation mechanisms allow the maintenance of cardiac output.
Definition of Mitral Insufficiency
Mitral valve insufficiency involves mitral valve changes that do not allow the valve to close properly. These changes can affect the annulus, cusp, chordae tendineae, and papillary muscles.
Epidemiology of Mitral Insufficiency
Distribution of mitral insufficiency
Next to valvular aortic stenosis, mitral valve insufficiency is the second most common disease of the heart valves, with an annual incidence of 2%.
Etiology of Mitral Insufficiency
Causes of mitral insufficiency
A relative mitral valve insufficiency occurs when the reason for the inability of the mitral valve to close can be attributed to the dilation of the mitral valve annulus. This can occur as part of a dilated cardiomyopathy. In an acute myocardial infarction, mitral valve prolapse, or CHD, the chordae tendineae and papillary muscles can be affected.
Calcification, as well as rheumatic and bacterial endocarditis, may result in mitral valve insufficiency. Degenerative changes can occur as part of conditions such as Ehler-Danlos syndrome, Marfan syndrome, or mitral valve prolapse syndrome.
Classification of Mitral Insufficiency
The 4 grades of severity of mitral insufficiency
Mitral valve insufficiency can be divided into 4 grades, just like aortic valve insufficiency, depending on the regurgitation fraction:
Grade I: Regurgitation fraction <20%. A little contrast agent enters the left atrium but is completely excreted again during systole.
Grade II: Regurgitation fraction 20–39%. The left atrium is completely filled with contrast agent but is weak after several heartbeats.
Grade III: Regurgitation fraction 40–60%. The left atrium is completely filled the contrast agent. The contrast medium density in the left atrium corresponds to the density in the left ventricle.
Grade IV: Regurgitation fraction >60%. The left atrium is completely filled with contrast again during the first or second heartbeat. The contrast medium density is higher in the left atrium than in the left ventricle. Reflux of the contrast agent into the pulmonary veins occurs.
Pathophysiology of Mitral Insufficiency
If the mitral valve does not close properly, the blood from the left ventricle is only partially directed into the systemic circulation. The other part is pumped into the left atrium again, and, since the pulmonary veins have no valves, the blood is pumped back into the pulmonary circulation. This leads to an accumulation of blood in the lungs and thus to pulmonary hypertension, right ventricular overload, and right heart failure.
Since the cardiac output would fall into the left atrium, due to the return flow, the left ventricle must intensify its work in order to maintain the cardiac output. This also causes increased strain on the left ventricle and leads to left ventricular hypertrophy and dilation.
Symptoms and Clinical Presentation of Mitral Insufficiency
Acute mitral insufficiency
The acute form of mitral valve insufficiency quickly leads to symptoms of heart failure with pulmonary edema, and even to cardiogenic shock, due to lack of time for decompensation.
Chronic mitral insufficiency
The chronic form may be asymptomatic for a long time and is associated with a good prognosis since the adaptation mechanisms are very good. Patients may complain of fatigue and dyspnea on exertion. Mitral valve insufficiency is only more pronounced at a higher grade and decompensation; dyspnea at rest and palpitations, as well as nocturnal coughing fits, can occur.
Progression and Special Types of Mitral Insufficiency
A distinction is made between acute and chronic mitral valve insufficiency. The cause of the acute form is bacterial endocarditis or acute myocardial infarction. Rheumatic mitral valve insufficiency has a 5-year survival rate of 80%. Generally, the ejection fraction can be maintained for a long time. The progression of the disease should still be monitored every 6–12 months.
Diagnosis of Mitral Insufficiency
Auscultation of mitral insufficiency
Signs during an examination are rare or are based on an eccentric left ventricular hypertrophy. Peripheral cyanoses can be present, as well as a widened and displaced apical impulse. In auscultation, a strip-shaped pansystolic murmur is noted, which is heard best over the cardiac apex. The sounds of this murmur are propagated into the axilla.
The first heart sound is soft, with a wide splitting of the second heart sound.
Sustained handgrip increases systematic vascular resistance and afterload. It is used to differentiate between aortic stenosis and mitral insufficiency. In mitral regurgitation, the murmur increases. In aortic stenosis, the murmur decreases.
Radiological examination of mitral insufficiency
ECG signs are dependent on the adaptation mechanisms of the heart. In pulmonary hypertension, a right axis deviation is noted, while in left ventricular hypertrophy, more of a horizontal heart can be seen. The P wave may have 2 peaks.
On chest X-ray, an enlarged heart can be seen. Pulmonary venous congestions may also be identified. The valvular apparatus should be assessed using echocardiography. The degree of insufficiency can also be determined.
Treatment of Mitral Insufficiency
Treatment options for mitral insufficiency
Conservative treatment of mitral regurgitation includes physical rest and, if the risk of atrial fibrillation exists, prevention of thromboembolism should be initiated with anticoagulants:
- Decrease afterload with ACIs/ARBs, especially if mitral insufficiency is associated with systolic dysfunction
- Decrease pulmonary congestion with diuretics and digitalis
Regular follow-ups ensure that indications for surgery are not overlooked. Once the contractility of the ventricle is restricted, there is a danger that even a reconstruction will not be able to help recover ventricular function. Ideally, a mitral valve repair should be performed. This can be achieved via minimally invasive or more invasive methods. A mitral valve replacement is possible, with a mechanical, as well as biological, prosthesis.
Complications of Mitral Insufficiency
One complication of mitral valve insufficiency is cardiac decompensation, which may cause pulmonary edema. Cardiac decompensation can also be triggered by atrial fibrillation.