Comprehensive Guide to AV Canal Repair: Procedure, Indications, and Benefits — Cost, Top Hospitals & Success Rates | MyMedicPlus

Atrioventricular canal repair, also known as AV canal repair or complete atrioventricular septal defect (AVSD) repair, is an open-heart surgical procedure that corrects a group of congenital heart malformations characterised by a defect in the central fibrous body of the heart involving both the atrial and ventricular septa, combined with abnormalities of the atrioventricular valves. The condition encompasses a spectrum from partial (ostium primum ASD with a cleft anterior mitral leaflet) to complete forms (large VSD, ASD, and a common AV valve).

The surgery is performed under general anaesthesia using cardiopulmonary bypass, which temporarily takes over the function of the heart and lungs, allowing the surgeon to operate on a still, bloodless field. The patient's core temperature is typically cooled to 18-28°C (deep hypothermia) to protect the brain and organs during the repair. A median sternotomy provides optimal exposure to the heart.

The clinical hallmarks of complete AVSD are a large left-to-right shunt at both atrial and ventricular levels, and regurgitation through the common AV valve, leading to congestive heart failure, failure to thrive, recurrent chest infections, and pulmonary hypertension if left uncorrected. Down syndrome (trisomy 21) is present in approximately 40-50% of complete AVSD cases, and children with Down syndrome characteristically develop pulmonary vascular disease more rapidly than chromosomally normal children.

Surgical correction is typically planned between 3 and 6 months of age in complete AVSD to prevent irreversible pulmonary hypertension. Preoperative assessment includes echocardiography to define the anatomy (Rastelli classification A, B, or C based on superior bridging leaflet morphology), cardiac catheterisation to assess pulmonary vascular resistance, and paediatric cardiac surgical planning.

Complete AVSD (also called complete atrioventricular septal defect or complete endocardial cushion defect) is the primary condition treated. It comprises: a large primum atrial septal defect at the base of the interatrial septum, a posterior inlet ventricular septal defect, and a single common AV valve with five leaflets (left and right mural leaflets, superior and inferior bridging leaflets, and a right anterosuperior leaflet) rather than separate mitral and tricuspid valves. Without repair, most children develop severe congestive heart failure, pulmonary hypertension, and Eisenmenger syndrome by the second or third decade of life.

Partial AVSD (ostium primum ASD with cleft mitral valve) is a milder variant treated by the same surgical principles — patch closure of the ASD and suture repair of the mitral valve cleft. Transitional AVSD is an intermediate form. Unbalanced AVSDs, where one ventricle is hypoplastic, may require staged single-ventricle palliation (Fontan pathway) rather than biventricular repair.

Ideal candidates for biventricular AV canal repair are infants between 3 and 6 months of age with complete AVSD, balanced ventricular sizes, pulmonary vascular resistance below 8 Wood units/m², and no major associated cardiac anomalies that preclude repair. Infants with Down syndrome are managed with the same criteria, with awareness that Eisenmenger syndrome may develop earlier and that early repair is therefore particularly critical. Infants with weight below 3.5 kg may benefit from a brief period of medical optimisation before surgery.

Contraindications include Eisenmenger syndrome (pulmonary vascular resistance fixed and elevated, with net right-to-left shunting), severely unbalanced AVSD with a hypoplastic left or right ventricle inadequate for biventricular repair, and significant associated anomalies that make complete repair hazardous. Patients with severe systemic disease, chromosomal anomalies incompatible with survival, or irreversible end-organ damage are generally not offered repair.

The two-patch technique uses separate patches (typically pericardium or Dacron) to close the VSD and ASD, with the common AV valve divided and reconstructed into separate mitral and tricuspid valves. This approach provides excellent visualisation and precise valve reconstruction and is favoured by many centres. The single-patch technique (original Carpentier technique) uses one patch placed across both defects, with the valve leaflets sutured to the patch crest; it is associated with a risk of left ventricular outflow tract obstruction.

The modified single-patch or Australian technique places the AV valve leaflets directly onto the ventricular septum without a VSD patch, reserving the atrial patch for ASD closure only. This simplifies the repair and may reduce left ventricular outflow tract obstruction. The choice among techniques depends on surgeon experience, institutional preference, and individual anatomy. Cleft mitral valve repair — suturing the cleft in the anterior mitral leaflet — is essential regardless of technique and determines long-term mitral competence. In older patients with elevated pulmonary vascular resistance, pulmonary artery banding as a palliative measure may be performed before definitive repair. The treating surgeon individualises the chosen technique based on patient anatomy, the extent and nature of the underlying condition, available equipment, and the balance of procedural benefit against risk — a decision made in consultation with the patient following a thorough informed consent discussion covering all available options.

Surgical repair of complete AVSD at high-volume congenital heart centres achieves hospital mortality below 2-3% for straightforward cases. Long-term survival at 20 years exceeds 80-90% in multiple series. Freedom from re-operation (for mitral valve regurgitation, AVSD re-intervention, or left ventricular outflow tract obstruction) is approximately 85% at 10 years. Patients with adequate repair and no residual haemodynamic lesions lead near-normal lives, attend school, and participate in age-appropriate physical activity.

Down syndrome patients have equivalent surgical outcomes to chromosomally normal patients in major series and derive equivalent haemodynamic benefit from repair. Early repair preserves pulmonary vascular bed function, allows normal somatic growth, prevents heart failure and hospitalisation, and significantly improves quality of life for both patients and families. Patient outcomes are optimised when surgery is performed by experienced specialists at high-volume accredited centres, where procedural volume correlates with reduced complication rates, shorter hospital stays, and superior long-term functional results compared to lower-volume institutions.

Residual or recurrent mitral valve regurgitation is the most common long-term complication, occurring in 10-20% of patients and requiring re-operation in 5-15% within 10 years. Left ventricular outflow tract obstruction can develop due to subaortic membrane formation, an abnormally positioned papillary muscle, or the repaired valve leaflet tissue causing dynamic obstruction, requiring re-intervention in 3-7% of cases. Complete heart block requiring permanent pacemaker implantation occurs in 1-3% of cases due to the proximity of the AV conduction bundle to the repair.

Early post-operative complications include junctional ectopic tachycardia (JET), residual shunts requiring re-operation, low cardiac output syndrome, and pulmonary hypertensive crises requiring inhaled nitric oxide. Wound infection, neurological complications from cardiopulmonary bypass, and renal dysfunction are also recognised. Children with Down syndrome have higher rates of pulmonary complications and may require longer ventilatory support.

Following AV canal repair, patients typically spend 5-14 days in the paediatric cardiac ICU and general ward before hospital discharge. Echocardiography before discharge assesses residual shunts, AV valve function, and ventricular function. Aspirin or anticoagulation may be prescribed if residual intracardiac abnormalities exist. Diuretic therapy is commonly needed for 3-6 months post-operatively.

Cardiology follow-up is lifelong, with echocardiography at 6 weeks, 6 months, annually for the first 5 years, and biannually thereafter. Endocarditis prophylaxis is recommended for at least 6 months post-repair and indefinitely if residual defects remain. Activity restrictions are usually lifted 3-6 months after successful repair. For children with Down syndrome, the multidisciplinary team integrates developmental paediatrics, cardiology, and family support throughout care.

In the United States, complete AV canal repair including ICU stay, cardiopulmonary bypass, and paediatric cardiac surgery fees ranges from $100,000-$250,000 depending on complexity and length of stay. In the UK, NHS treatment is available but waiting times may affect planning. Private costs in the UK range from £40,000-£80,000.

High-volume paediatric cardiac surgery centres in India (AIIMS New Delhi, Narayana Health, Apollo Hospitals) perform AV canal repairs for $5,000-$12,000 with outcomes comparable to international benchmarks. Thailand (Bumrungrad) and Turkey (Acibadem) offer similar quality at $8,000-$15,000, representing 70-85% savings. JCI accreditation and published institutional outcomes data should be verified before selecting a centre for paediatric cardiac surgery abroad. International patients should factor in the cost of pre-operative testing, post-operative accommodation during recovery, translation services where required, and travel insurance including medical evacuation cover when planning overseas medical treatment.

Pulmonary artery banding is a palliative procedure that reduces pulmonary blood flow by narrowing the main pulmonary artery with a constricting band, providing temporary relief of heart failure symptoms in infants too small or sick for complete repair. It does not correct the underlying anatomy and requires definitive repair 3-6 months later after appropriate growth.

For unbalanced AVSD where one ventricle is too small for biventricular repair, staged single-ventricle palliation — Norwood or modified BT shunt, followed by bidirectional Glenn at 3-6 months, and Fontan completion at 2-4 years — is the alternative pathway. Medical management of heart failure (diuretics, ACE inhibitors, digoxin) provides symptomatic relief but does not prevent pulmonary vascular disease and is not an alternative to surgical repair in complete AVSD.