Pediatric Mitral Regurgitation (Mitral Valve Insufficiency) Clinical Presentation

The nature and severity of symptoms in patients with mitral regurgitation (MR) (mitral valve insufficiency) relates to etiology, rate of onset and progression, left ventricle (LV) function, pulmonary artery pressure, and the presence of preexisting valvular or myocardial diseases.

Children with minor degrees of mitral regurgitation are usually asymptomatic. With increased amounts of mitral regurgitation, fatigue may be reported, but, surprisingly, children can tolerate more severe mitral regurgitation better than adults can. Once pulmonary hypertension develops, complaints such as tachypnea and dyspnea with light activity become more prominent. With the most severe mitral regurgitation, children may experience limited growth and failure to thrive. Hemoptysis can develop during the later stages.

Children may also remain asymptomatic, with no complications of mitral regurgitation until the second or third decade of life.

An indolent course of mitral regurgitation may be deceptive because of the ability of the heart to compensate for the altered hemodynamics. This occurs due to changes in cardiac pump loading such that increased diastolic filling increases preload, whereas LV ejection, in part into the left atrium, reduces afterload. By the time symptoms become apparent, serious and irreversible LV dysfunction may have developed.

Vital signs

Vital signs are usually normal in those with mild regurgitation. With increasing severity of mitral regurgitation (MR) (mitral valve insufficiency), heart and respiratory rates may be increased. In patients with severe mitral regurgitation, arterial pulse has been characterized as having a small volume with a sharp upstroke.

Rarely, irregular pulse may be indicative of associated atrial fibrillation.

Cardiac examination

Apical impulse

A left atrial lift is a second impulse resulting from the increased volume that is displaced into the left atrium during systole. The second impulse should be felt near the time of the second heart sound. This sign is most helpful in thin children and young adults, because their chest diameters are smaller and their hearts are closer to the chest wall. The cardiac impulse may be displaced to the left, and, in more advanced disease, a double impulse is felt.

Heart sounds

Upon auscultation, the first heart sound is usually slightly diminished, whereas the second heart sound is usually split. With more severe mitral regurgitation, a third heart sound and a mid-diastolic low frequency murmur may be present, caused by increased ventricular filling. When pulmonary hypertension develops, the pulmonary component of the second heart sound becomes louder and occurs earlier (as long as right ventricular function is not significantly impaired), reducing the splitting interval.

An ejection systolic click may be present due to mitral valve prolapse.

Murmur

Patients with mild mitral regurgitation may reveal no signs other than a characteristic apical systolic murmur. The mitral regurgitation murmur is characterized as blowing and high pitched, and it is loudest over the apex with radiation to the left axilla. The murmur is often pansystolic, beginning immediately after the first heart sound, and it may continue beyond the aortic component of the second heart sound, thus obscuring the second heart sound. This murmur increases with increased afterload (squatting) and decreases with decreased preload (standing). Occasionally, radiation toward the sternum occurs when posterior leaflet abnormalities are present. Little correlation is noted between the intensity of the murmur and the severity of the mitral regurgitation. The murmur occasionally may be confined to late systole only. The degree of mitral regurgitation in these patients is usually mild.

Other physical findings

Congestive heart failure with pulmonary edema can occur with significant mitral regurgitation and pulmonary findings may be consistent with it. Compression of the left main bronchus due to left atrial enlargement can cause ipsilateral wheezing and lung collapse. Significant and sustained mitral regurgitation can be associated with endocarditis and thromboembolism and have the associated findings.

The first classification of mitral regurgitation (MR) (mitral valve insufficiency) is based on the etiology (congenital vs acquired).

Congenital

Congenital cardiac malformation: Most mitral regurgitation in the pediatric population is congenital in origin secondary to a deformed or dysplastic valve.

• Isolated mitral valve defects: Mitral valve clefts, fenestrations or perforations, double orifice mitral valve, arcade mitral valve, hammock mitral valve, abnormal chordal tissue or insertion, absent or hypoplastic leaflets, accessory leaflets

• Associated with other congenital heart defects: Endocardial cushion defects (atrioventricular septal defects), transposition of the great arteries, anomalous origin of the left coronary artery

Degenerative disease: Myxomatous degeneration of the mitral valve is usually progressive.

Acquired

In older adolescent and adult patients, mitral regurgitation is likely to be acquired. In these patients, mitral regurgitation can result from numerous problems, including the following:

• Infection: Endocarditis and myocarditis

• Inflammation: Rheumatic heart disease, Kawasaki disease, Sweet syndrome and systemic lupus erythematosus

• Structural disorders: Ischemic heart disease and trauma

• Ischemic: Anomalous origin of the left coronary artery, perinatal asphyxia, myocardial infarction

The second classification of mitral regurgitation (MR) (mitral valve insufficiency) is based on anatomy.

Mitral annulus disorders

• Infective endocarditis: Abscess formation

• Trauma: Valvular heart surgery

• Paravalvular leak resulting from suture interruption: Surgical technical problems, infective endocarditis

• Cardiomyopathy: Annular dilatation

Mitral leaflet disorders

• Infective endocarditis: Perforation or interference with valve closure by vegetation

• Trauma: Tear during percutaneous mitral balloon valvotomy or penetrating chest injury

• Tumors: Atrial myxoma

• Myxomatous degeneration

• Systemic lupus erythematosus: Libman-Sacks lesion

• Acute rheumatic fever

Disorder of chordae tendineae

• Idiopathic (eg, spontaneous)

• Degenerative disease: Mitral valve prolapse, Marfan syndrome, Ehlers-Danlos syndrome

• Infective endocarditis

• Acute and chronic rheumatic fever

• Trauma: Percutaneous balloon valvuloplasty, blunt chest trauma

Papillary muscle disorders

• Coronary artery disease (causing dysfunction and, rarely, rupture)

• Acute global left ventricular dysfunction

• Infiltrative diseases: Amyloidosis, sarcoidosis

• Trauma

• Tumors

The third classification of mitral regurgitation (MR) (mitral valve insufficiency) is based on whether the disease is acute or chronic.

Acute causes

• Traumatic (eg, percutaneous balloon valvuloplasty, blunt chest trauma)

• Ischemic (eg, perinatal asphyxia, anomalous origin of left coronary artery from pulmonary artery, myocardial infarction)

• Neonatal (eg, perinatal asphyxia)

• Infective (eg, infective endocarditis, myocarditis)

Chronic causes

• Congenital disorders: Mitral valve clefts or fenestrations, parachute mitral valve abnormality, part of any associated congenital heart disease (endocardial cushion defects, transposition of the great arteries, anomalous origin of the left coronary artery) ^[5]

• Inflammatory disorders: Rheumatic heart disease, Kawasaki disease, systemic lupus erythematosus, scleroderma

• Degenerative disorders: Myxomatous degeneration of mitral valve leaflets (Barlow click-murmur syndrome, prolapsing leaflet, mitral valve prolapse), Marfan syndrome, Ehlers-Danlos syndrome, pseudoxanthoma elasticum, calcification of mitral valve annulus

• Infective disorders: Infective endocarditis, myocarditis

• Cardiomyopathy: Dilated cardiomyopathy (dilation of mitral valve annulus and left ventricular [LV] cavity [congestive cardiomyopathies, aneurysmal dilation of the LV]), ^[6]  hypertrophic cardiomyopathy, restrictive cardiomyopathy, noncompaction cardiomyopathy

The fourth classification of mitral regurgitation (MR) (mitral valve insufficiency) is based on mitral valve dysfunction as elucidated by Carpentier and colleagues. ^[7]

• Type I: Normal leaflet and chordal motion (eg, fenestrations, clefts, perforations in the leaflets)

• Type II: Leaflet prolapse with excessive chordal motion above annulus (eg, mitral valve prolapse)

• Type III: Restrictive leaflet or chordal motion (eg, parachute mitral valve)