Pediatric Congenital Heart Disease Introduction Anatomical Types Clinical Features Diagnosis Management Complications & Prognosis

Congenital Mitral Stenosis

Introduction

Congenital Mitral Stenosis (CMS) is a rare but significant congenital heart defect characterized by obstruction to left ventricular inflow due to various anatomical abnormalities of the mitral valve apparatus.

Epidemiology

• Incidence: 0.2% - 0.4% of all congenital heart defects
• Gender distribution: Slight female predominance
• Associated conditions present in up to 90% of cases
• Part of Shone's Complex in 60-85% of cases

Pathophysiology

• Primary Effects:
  • Restricted flow across mitral valve
  • Increased left atrial pressure
  • Pulmonary venous hypertension
  • Secondary pulmonary arterial hypertension
• Hemodynamic Consequences:
  • Decreased left ventricular filling
  • Reduced cardiac output
  • Right ventricular strain
  • Development of collateral circulation

Anatomical Classifications

Morphological Types

• Typical Congenital MS (60%):
  • Thickened leaflets
  • Short, thickened chordae tendineae
  • Reduced interpapillary muscle distance
  • Obliteration of interchordal spaces
• Hypoplastic Mitral Valve (15-20%):
  • Small annulus
  • Reduced leaflet tissue
  • Shortened chordae
  • Often associated with left heart hypoplasia
• Supravalvar Mitral Ring (10-15%):
  • Fibrous ridge above mitral valve
  • Variable circumferential involvement
  • May be complete or partial
• Double Orifice Mitral Valve (5-10%):
  • Two separate valve orifices
  • Bridge of tissue between orifices
  • Can be equal or unequal in size
• Parachute Mitral Valve (5%):
  • Single papillary muscle
  • All chordae insert into one muscle
  • Funnel-shaped valve apparatus

Associated Anomalies

• Shone's Complex Components:
  • Supravalvar mitral ring
  • Parachute mitral valve
  • Subaortic stenosis
  • Coarctation of aorta
• Other Common Associations:
  • Ventricular septal defect
  • Aortic stenosis
  • Patent ductus arteriosus
  • Atrial septal defect

Clinical Features

Symptom Progression

• Neonatal Period:
  • Respiratory distress
  • Poor feeding
  • Failure to thrive
  • Cyanosis in severe cases
• Infancy:
  • Recurrent respiratory infections
  • Growth retardation
  • Exercise intolerance
  • Pulmonary edema
• Childhood:
  • Exercise limitation
  • Easy fatigability
  • Hemoptysis in severe cases
  • Right heart failure symptoms

Physical Examination

• General Appearance:
  • Growth retardation
  • Respiratory distress
  • Central cyanosis in severe cases
• Cardiac Examination:
  • Loud S1
  • Opening snap
  • Diastolic rumble at apex
  • Right ventricular heave
  • P2 accentuation
• Respiratory Findings:
  • Tachypnea
  • Rales
  • Decreased breath sounds
  • Pleural effusion in severe cases

Diagnostic Approach

Initial Evaluation

• Chest X-ray:
  • Left atrial enlargement
  • Pulmonary venous congestion
  • Kerley B lines
  • Cardiomegaly
• ECG Findings:
  • Left atrial enlargement
  • Right ventricular hypertrophy
  • Right axis deviation
  • P mitrale pattern

Advanced Imaging

• Echocardiography:
  • Primary diagnostic tool
  • Valve morphology assessment
  • Mitral valve gradient measurement
  • Associated lesions identification
  • Pulmonary pressure estimation
• 3D Echocardiography:
  • Detailed valve anatomy
  • Surgical planning assistance
  • Precise orifice area measurement
• Cardiac MRI:
  • Comprehensive anatomical assessment
  • Flow quantification
  • Ventricular function evaluation
  • Associated anomalies detection
• Cardiac Catheterization:
  • Hemodynamic assessment
  • Direct pressure measurements
  • Pulmonary vascular resistance
  • Therapeutic intervention planning

Management Strategies

Medical Management

• Initial Stabilization:
  • Diuretics for congestion
  • Afterload reduction
  • Pulmonary hypertension management
  • Nutrition optimization
• Specific Medications:
  • Loop diuretics (Furosemide)
  • Spironolactone
  • Sildenafil for pulmonary hypertension
  • Beta-blockers in selected cases

Surgical Intervention

• Timing Considerations:
  • Symptomatic status
  • Growth parameters
  • Associated lesions
  • Pulmonary vascular status
• Surgical Options:
  • Valve repair techniques:
    • Commissurotomy
    • Chordal shortening
    • Papillary muscle splitting
    • Annular enlargement
  • Valve replacement:
    • Mechanical valve
    • Bioprosthetic valve
    • Size considerations

Complications & Prognosis

Early Complications

• Immediate Post-operative:
  • Low cardiac output syndrome
  • Bleeding
  • Arrhythmias
  • Pulmonary complications
• Early Post-operative:
  • Residual stenosis
  • Mitral regurgitation
  • Heart block
  • Wound infection

Long-term Complications

• Valve-related:
  • Restenosis
  • Prosthetic valve dysfunction
  • Endocarditis
  • Thromboembolism
• Cardiac:
  • Progressive pulmonary hypertension
  • Right heart failure
  • Atrial fibrillation
  • Ventricular dysfunction

Prognosis

• Factors Affecting Outcome:
  • Age at presentation
  • Severity of stenosis
  • Associated anomalies
  • Timing of intervention
  • Type of surgical repair
• Long-term Follow-up Requirements:
  • Regular echocardiographic assessment
  • Anticoagulation monitoring
  • Growth and development tracking
  • Exercise capacity evaluation

Disclaimer

The notes provided on Pediatime are generated from online resources and AI sources and have been carefully checked for accuracy. However, these notes are not intended to replace standard textbooks. They are designed to serve as a quick review and revision tool for medical students and professionals, and to aid in theory exam preparation. For comprehensive learning, please refer to recommended textbooks and guidelines.