Chordae Tendineae Agenesis

Definition

Chordae tendineae agenesis is a rare congenital anomaly of the mitral valve characterized by the partial or complete absence of the chordae tendineae, the thin fibrous structures that connect the valve leaflets to the papillary muscles. This condition compromises the normal mobility of the valve, leading to reduced leaflet excursion and, in severe cases, significant mitral stenosis or regurgitation. The anomaly can occur in isolation or in association with other congenital heart diseases, such as parachute mitral valve, atrioventricular septal defect (AVSD), or Shone’s syndrome. In neonates with severe forms, the absence of chordae can cause critical obstruction of mitral flow, with potentially life-threatening hemodynamic consequences.

Embryology and Pathogenesis

Chordae tendineae develop during the early weeks of gestation through a remodeling process of myocardial trabeculae. If this mechanism is altered, the chordae may fail to differentiate, leading to a direct connection between the valve leaflets and the papillary muscles or their complete absence. The main causes include:

• Defects in embryological development: abnormalities in the formation of chordae tendineae may impair their structure.
• Genetic mutations: alterations in genes involved in collagen and structural protein development of the mitral valve.
• Persistence of primitive structures: some theories suggest that the failure of embryonic tissue regression may prevent normal chordae formation.

Pathophysiology

Chordae tendineae agenesis profoundly alters mitral valve mechanics. In mild cases, the valve may function relatively well, whereas in severe forms, reduced valve opening leads to mitral stenosis. If the valve leaflets lack adequate support, they may become hypermobile, resulting in significant mitral regurgitation. The main hemodynamic consequences include:

• Increased left atrial pressure: in cases of mitral stenosis, blood encounters resistance when passing into the left ventricle.
• Pulmonary congestion: difficulty in left atrial emptying can lead to dyspnea and pulmonary edema.
• Reduced cardiac output: in severe cases, impaired left ventricular filling compromises systemic perfusion.

Clinical Manifestations

The severity of symptoms depends on the degree of valvular dysfunction. In mild cases, the patient may remain asymptomatic for years, with a heart murmur as the only sign of the condition. However, in moderate or severe cases, symptoms may include: Exertional dyspnea due to increased left atrial pressure and pulmonary congestion, fatigue resulting from reduced cardiac output, and palpitations due to left atrial dilation and the potential development of atrial fibrillation. On cardiac auscultation, a mitral murmur may be detected in cases of stenosis or regurgitation. Neonates with critical forms may present with early heart failure symptoms such as tachypnea, feeding difficulties, and poor weight gain.

Diagnosis

Diagnosis is based on advanced imaging techniques. Transthoracic echocardiography with Doppler is the first-line diagnostic tool, allowing for the assessment of mitral valve morphology and the presence of stenosis or regurgitation. In more complex cases, transesophageal echocardiography provides a more detailed view of the valvular structures. Cardiac magnetic resonance imaging (CMR) is useful for three-dimensional assessment of the valvular apparatus. Cardiac catheterization is indicated in patients with associated pulmonary hypertension or for more precise hemodynamic evaluation.

Treatment

The therapeutic approach depends on the severity of valvular dysfunction. In mild cases, clinical monitoring with regular follow-ups may be sufficient, while more severe forms require corrective intervention. Treatment options include:

• Mitral valve repair: indicated when the defect can be corrected with valvular remodeling techniques.
• Mitral valve replacement: required when the valve is irreparable.
• Percutaneous approaches: reserved for high-risk surgical patients.

Prognosis

Prognosis depends on the severity of the condition and the timeliness of treatment. In patients with mild forms, the quality of life is generally good, with regular follow-ups to monitor disease progression. In severe cases, early intervention can prevent progression to heart failure and improve cardiac function.

Conclusion

Chordae tendineae agenesis is a rare congenital heart defect that can significantly impact mitral valve function. Early diagnosis and timely treatment are crucial to ensure a favorable prognosis and improve the patient’s quality of life.

References
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