Acleistocardia: A Rare Ventricular Septal Defect Overview

Acleistocardia (from Greek a- "without" + kleistos "closed" + kardia "heart") is a rare, severe congenital heart defect characterized by complete absence of the interventricular septum, resulting in a single, common ventricular chamber.

Anatomy and Pathophysiology

• Failure of septation during cardiac looping (weeks 4–7 gestation).
• Results in a single ventricle receiving blood from both atria.
• Complete mixing of systemic and pulmonary venous return.
• Pulmonary blood flow depends on pulmonary vascular resistance (no anatomic restriction).
• Cyanosis varies: early may be acyanotic (high PVR), later cyanotic as PVR drops.
• Associated anomalies common: transposition, single atrium, AV valve anomalies, heterotaxy.

Clinical Presentation

• Neonatal cyanosis, heart failure, failure to thrive, recurrent respiratory infections.
• Loud, single S₂; holosystolic murmur (if VSD restrictive); pulmonary flow murmur.
• ECG: biventricular hypertrophy or single ventricle pattern.

Diagnosis

• Prenatal: Fetal echocardiography (18–22 weeks).
• Postnatal: Echocardiography (definitive); cardiac MRI/CT for anatomy; cardiac catheterization for hemodynamics.

Management

• Palliative (staged single ventricle pathway):
  • Neonate: Prostaglandin E1 (if ductal-dependent pulmonary flow) or pulmonary artery banding (if excessive pulmonary flow).
  • 4–6 months: Bidirectional Glenn (superior cavopulmonary connection).
  • 2–4 years: Fontan completion (total cavopulmonary connection).
• Biventricular repair rarely possible (requires adequate ventricular mass, two functional AV valves).
• Heart transplantation considered for failed Fontan or unsuitable anatomy.

Prognosis

Without intervention, fatal in infancy. Staged palliation yields ~70–80% 10-year survival in experienced centers. Lifelong cardiology follow-up for Fontan complications (protein-losing enteropathy, plastic bronchitis, arrhythmias, liver fibrosis).

Genetic counseling recommended (associated with heterotaxy syndromes, cilia motility genes).