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  • • A congenital heart lesion that increases pulmonary artery (PA) blood flow

    • Causes left to right shunt, results in lung infection, pulmonary vascular congestion, PA hypertension, right heart failure, pulmonary vasoconstriction, pulmonary vascular obstructive disease

    Eisenmenger syndrome: Increased pulmonary hypertension to such extent that left to right shunt ceases and shunt becomes right to left, requiring heart-lung transplant

    • Inhaled nitric oxide, oxygen, or IV tolazoline reverses PA vasoconstriction

    • PA band is palliative and can reduce PA flow to alleviate RV failure and progression of pulmonary hypertension

    • Deficiency of tissue in central region of heart (lower atrial septum-septum primum, mitral valve, tricuspid valve)

    • Defect in endocardial and conal tissue development

    • Range of defects possible

    Partial AV canal defect: Septum primum atrial septal defect (ASD), deficient lower atrial septum only

    Transitional AV canal defect: Intermediate form with ASD and minor deficiency in upper ventricular system

    Complete AV canal defect: ASD and severe valve anomalies

    • Associated with left superior vena cava (SVC), additional ventricular septal defect (VSD), anomalous pulmonary venous connection, patent ductus arteriosus (PDA), tetralogy of Fallot




  • • Can occur in patients with trisomy 21 (Down syndrome) who are more prone to pulmonary vascular obstructive disease


Symptoms and Signs


  • • Heart failure common in infancy

    • Cardiomegaly present

    • Blowing pansystolic murmur (varies)

    • Loud S2, fixed split

    • Left to right shunt modified by mitral regurgitation

    • Severity depends on structural defects

    • Partial defect may be asymptomatic

    • Pulmonary hypertension and mitral regurgitation natural history


Laboratory Findings


  • ECG: Left axis deviation and counterclockwise frontal QRS vector loop


Imaging Findings


  • • Echocardiography best for diagnosis

    • Catheterization for patients older than 6 mos if pulmonary hypertension is a concern


  • • Must define extent of canal defect to plan correction


  • • Echocardiography

    • Cardiac catheterization if patient is older than 6 months


  • • Timing of correction indicated by degree of anomaly and symptoms

    Partial defect: Patch closure

    Complete defect: Patch closure of septal defects and reconstruction of valves (suture closure of valve with or without annuloplasty)






  • • Defect warrants repair

    Complete defect: Repair by 6 months of age

    • -Repair by 1 year of age in other less severe types

    Mitral regurgitation: Repair regardless of age




  • Postoperative mitral regurgitation: 10-40%, 10% require reoperation

    • Many patients will require additional mitral valve work in adulthood




  • • Mortality varies with defect and age

    Partial defect: 10-year survival is 98%

    Complete defect:

    • -Operative mortality is 3-5%

      -10-year survival is 90%

      -< 1 year life expectancy from congestive heart failure



Backer CL, Stewart RD, Mavroudis C: What ...

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