persistent ostium primum (partial atrioventricular canal)

Pathology

• congenital opening in septum near AV valves
• cleft mitral valve leaflet common
• left atrial enlargement may occur secondary to mitral regurgitation
• associated anomalies
  • mitral & tricuspid valve anomalies
  • ventricular septal defect

Clinical manifestations

• dyspnea
• round chest, precordial bulge rare
• no cyanosis or clubbing of fingers
• accentuated precordial apical thrust
  • volume overload
  • elevated central venous pressure
  • right ventricular lift
• accentuated P2 with fixed splitting during inspiration & expiration
• systolic thrill near sternal border
• harsh systolic murmur (mitral regurgitation)
  • at left sternal border
  • transmitted to maxilla
• occasional apical mid diastolic murmur

Diagnostic procedures

• electrocardiogram:
  • left axis deviation*
  • late R' in right-sided leads
  • 1st degree AV block (75%)
  • left atrial enlargement may be present

* distinguishing feature from persistent ostium secundum

Radiology

• enlarged ventricles, left & right
• enlarged pulmonary arteries
  • increased pulmonaru vascularity
• left atrial enlargement may be present

Complications

• right ventricular hypertrophy
• right atrial enlargement
• atrial fibrillation
• mitral regurgitation (from mitral valve cleft)
• pulmonary hypertension (rare)

More general terms

• congenital heart disease; congenital cyanotic heart disease
• atrial septal defect (ASD)