Congenital Mitral Valve Anomalies: Symptoms, Types, Causes and Treatment

Congenital mitral valve anomalies are rare but complex heart defects present at birth, affecting the structure and function of the mitral valve—the gateway between the heart's left atrium and left ventricle. Although these conditions are uncommon, their impact can be profound, ranging from silent, clinically insignificant changes to life-threatening complications in infants, children, and adults. Understanding the spectrum of symptoms, types, causes, and treatments is essential for patients, families, and healthcare professionals alike.

Symptoms of Congenital Mitral Valve Anomalies

The symptoms of congenital mitral valve anomalies can be highly variable. Some individuals may remain asymptomatic for years, while others, especially infants and young children, may present with critical symptoms soon after birth. Recognizing these signs early is crucial for timely diagnosis and intervention.

Symptom	Description	Typical Age/Onset	Source(s)
Heart Failure	Rapid breathing, poor feeding, fatigue	Infancy/early childhood	9, 8
Murmurs	Abnormal heart sounds	Detected at any age	1, 4, 11
Pulmonary Hypertension	Elevated lung blood pressure	Infants/children	9, 8
Exercise Intolerance	Fatigue, shortness of breath	Children/adolescents	11, 9
Asymptomatic	No noticeable symptoms	Any age	1, 4, 6

Table 1: Key Symptoms

Understanding the Presentation of Symptoms

Heart Failure and Respiratory Distress

For many infants with severe congenital mitral valve defects, the first signs are related to heart failure. Symptoms can include rapid breathing, difficulty feeding, excessive sweating, and failure to thrive. In older children, fatigue and exercise intolerance may be more prominent 9, 8.

Heart Murmurs

Heart murmurs—a telltale sign of abnormal blood flow across the mitral valve—are often the first clinical clue. They can be detected during routine exams even in asymptomatic patients 1, 4, 11.

Pulmonary Hypertension

Increased pressure in the lungs can develop if mitral stenosis or regurgitation is significant, leading to symptoms like shortness of breath and poor growth 9, 8.

Variability and Silent Presentations

Not all congenital mitral valve anomalies present with symptoms early on. Some children and even adults may remain asymptomatic, with the anomaly discovered incidentally during imaging, surgery for other heart defects, or unrelated medical evaluations 1, 4, 6.

Types of Congenital Mitral Valve Anomalies

Congenital mitral valve anomalies comprise a diverse range of structural defects, each with unique anatomical features and clinical implications. Understanding the main types is essential for accurate diagnosis and management.

Type	Key Feature	Frequency/Notes	Source(s)
Parachute Mitral Valve	Chordae attach to one papillary muscle	Common in infants	1, 4, 3
Mitral Stenosis	Narrowed mitral valve opening	Multiple causes	1, 4, 9
Cleft Mitral Valve	Split in mitral leaflet	Can cause regurgitation	5, 1, 4
Double-Orifice Mitral Valve	Two separate valve openings	Rare	1
Supravalvular Mitral Ring	Membranous ring above valve	Often associated lesions	1, 4
Anomalous Mitral Arcade	Short/fused chordae, direct papillary insertion	Incompetence	7, 4
Accessory Mitral Tissue	Extra valve tissue present	Rare	4, 5
Hypoplastic or Malposition	Small/rotated valve, abnormal papillary muscles	Variable	5, 4, 3

Table 2: Main Types of Congenital Mitral Valve Anomalies

Detailed Exploration of Major Types

Parachute Mitral Valve

This classic anomaly features all chordae tendineae (fibrous strings) attaching to a single papillary muscle rather than two. This configuration restricts valve movement and typically causes mitral stenosis in infants and young children. It's frequently associated with other left-sided heart obstructions and conditions like coarctation of the aorta 1, 4, 3.

Congenital Mitral Stenosis

Mitral stenosis refers to a narrowing of the valve, which can result from various anomalies:

• Parachute mitral valve
• Supravalvular mitral ring
• Hypoplastic (underdeveloped) mitral valve
• Fusion of valve leaflets or chordae

These variants impede blood flow from the left atrium to the left ventricle, leading to increased pressure and symptoms of heart failure 1, 4, 9.

Cleft Mitral Valve

A cleft in the mitral leaflet—usually the anterior leaflet—creates a gap, resulting in mitral regurgitation (backward leakage of blood). Clefts may occur as isolated defects or as part of complex anomalies like atrioventricular canal defects 5, 1, 4.

Double-Orifice Mitral Valve

A rare condition in which two separate openings exist within the mitral valve, often leading to abnormal blood flow and, sometimes, regurgitation or stenosis 1.

Supravalvular Mitral Ring

A thin, fibrous or membranous ring located just above the mitral valve can restrict the valve opening. This lesion is rarely isolated and typically coexists with other anomalies such as the parachute mitral valve 1, 4.

Anomalous Mitral Arcade

This defect involves either direct or abnormally short connections between papillary muscles and the mitral leaflets, bypassing the normal chordae tendineae. It usually causes significant mitral regurgitation and is often detected in infancy 7, 4.

Other Rare Types

• Accessory Mitral Tissue: Extra tissue can disrupt normal valve function 4, 5.
• Hypoplastic or Malpositioned Valve: The valve may be too small or abnormally oriented, often seen with complex congenital heart disease 5, 4, 3.
• Aneurysmal Deformities: Rare cases of mitral valve aneurysm have been described, sometimes associated with excessive tissue and abnormal papillary muscles 2.

Causes of Congenital Mitral Valve Anomalies

The origins of congenital mitral valve anomalies are rooted in complex embryological development, with genetic, environmental, and sometimes unknown factors playing roles. Some anomalies arise as isolated defects, while others appear as part of syndromic or multilevel heart malformations.

Cause	Description	Associated Conditions	Source(s)
Embryological Maldevelopment	Abnormal valve formation in utero	Often part of multi-level defects	6, 4, 5
Genetic Factors	Heritable or syndromic defects	AV canal, TGA, coarctation	5, 4, 3
Associated Heart Defects	Co-occurrence with other malformations	Coarctation, TGA, AV canal	3, 4, 5
Sporadic/Unknown	No clear cause identified	Isolated cases	6, 4

Table 3: Causes and Associations

Embryological Development and Malformations

Valve Formation Gone Awry

During fetal development, the mitral valve forms from complex interactions between endocardial cushions and the ventricular myocardium. Disruptions at various stages can affect the leaflets, chordae, papillary muscles, or commissures, resulting in the diverse array of anomalies seen clinically 6, 4.

Genetic and Heritable Syndromes

Certain anomalies are more likely in patients with genetic syndromes or familial congenital heart disease. For example:

• Atrioventricular Canal Defects: Strongly linked to mitral cleft and other valve anomalies 5, 4.
• Transposition of the Great Arteries (TGA): Associated with abnormal mitral valve morphology in up to 22% of cases 5.
• Coarctation of the Aorta: High incidence of mitral anomalies, especially parachute deformity 3, 4.

Multilevel and Associated Defects

Mitral valve anomalies rarely occur in isolation. They may be part of broader left-sided obstructive heart disease (e.g., Shone's complex), or coincide with ventricular septal defects, aortic stenosis, and other anomalies 3, 5, 4.

Idiopathic/Sporadic Cases

Despite advances in genetics and imaging, many cases remain unexplained, with no identifiable genetic or environmental triggers 6, 4.

Treatment of Congenital Mitral Valve Anomalies

Treatment strategies for congenital mitral valve anomalies have advanced significantly, prioritizing valve repair over replacement whenever possible. Management is tailored to the specific anomaly, severity of symptoms, and the presence of associated heart defects.

Treatment	Key Features	Outcomes/Considerations	Source(s)
Medical Management	Diuretics, afterload reduction	For mild/moderate symptoms	8, 9, 11
Surgical Repair	Valve reconstruction preferred	Low mortality, good function	8, 9, 11
Valve Replacement	Mechanical/prosthetic valve	For unrepairable valves	10, 11, 9
Reoperation	Repeat repairs or replacement	May be required in complex disease	8, 9, 11

Table 4: Summary of Treatment Approaches

Approaches to Management

Medical Therapy

In mild cases or as a bridge to surgery, medications such as diuretics and afterload reducers can help control symptoms of heart failure and pulmonary hypertension. Medical management alone is rarely curative but is essential for stabilization 8, 9, 11.

Surgical Repair: The Gold Standard

Whenever feasible, surgical repair of the native mitral valve is preferred, especially in children. Techniques vary depending on the anomaly, including:

• Cleft closure
• Resection of supravalvular rings
• Papillary muscle splitting
• Reconstruction of chordae or leaflets

Repair offers better long-term outcomes, preserves the child's own tissue, and avoids complications associated with prosthetic valves (thrombosis, need for anticoagulation, and growth mismatch) 8, 11, 9.

Outcomes of Repair

• Low operative mortality (sometimes zero in large series)
• Most patients achieve good or excellent heart function postoperatively
• Some need reoperation due to the complexity or progression of disease 8, 9, 11

Valve Replacement

When the valve is too malformed to repair, mechanical or bioprosthetic replacement is considered. This is more common in complex or recurrent cases, or when previous repairs have failed.

Considerations with Replacement

• Higher risks in infants and young children (especially under 2 years old)
• Need for lifelong anticoagulation with mechanical valves
• Prosthetic valves do not grow with the child, often necessitating future replacement
• Survival and functional outcomes are generally good, but early mortality risk is increased in the youngest patients 10, 11, 9

Reoperations and Long-Term Management

Reintervention rates are significant due to the complexity of congenital mitral valve disease. Repeat repairs are often successful and preferred over replacement when possible. Long-term follow-up with serial echocardiography is essential to monitor valve function and detect complications early 8, 9, 11.

Conclusion

Congenital mitral valve anomalies represent a diverse and challenging group of heart defects that require careful, individualized management. From subtle, silent cases to severe, life-threatening disease in infants, early recognition and a multidisciplinary approach are vital.

Key Points:

• Symptoms range from asymptomatic to severe heart failure, depending on the anomaly and age at presentation.
• Types of anomalies are highly variable and include parachute mitral valve, cleft valves, supravalvular rings, and more, often as part of complex heart disease.
• Causes stem from embryological maldevelopment, with genetic and associated cardiac defects playing significant roles.
• Treatment prioritizes surgical repair, with valve replacement reserved for unrepairable cases. Outcomes are generally favorable with timely intervention, but reoperations may be necessary.

By deepening our understanding of these anomalies, clinicians can offer better care, and families can approach these diagnoses with greater confidence and hope for a positive outcome.