Name
COMPLETE ATRIOVENTRICULAR (AV) CANAL
DESCRIPTION
DETAIL
CAUSE : Defective development of the endocardial cushions -------------------------------------------------------------------------- DIFFERENTIAL DIAGNOSIS : β’ Atrial septal defect β’ Ventricular septal defect β’ Incomplete or intermediate AV canal β’ Patent ductus arteriosus β’ Mitral valve prolapse β’ Secondary mitral regurgitation β’ Pulmonary vascular obstructive disease β’ Anomalous pulmonary venous returnSPECIAL TESTS β’ Cardiac 2-D echo-Doppler showing anatomic defect, increased pulmonary pressures, mitral regurgitation, tricuspid regurgitation, right and left atrial and ventricular enlargements β’ ECG - superior QRS axis, right ventricular hypertrophy (RVH), left ventricular hypertrophy (LVH), possibly peaked P waves IMAGING: β’ Cardiac angiogram demonstrating AV canal and mitral and tricuspid regurgitation, left and right atrial and ventricular enlargement β’ Chest x-ray showing increased pulmonary vasculature, left and right atrial and ventricular enlargement β’ MRI offers excellent imaging of crux DIAGNOSTIC PROCEDURES : β’ Pulmonary artery catheter showing prominent V waves, elevated pulmonary capillary wedge pressures, right atrial step-up in oxygen saturations β’ Angiography
TYPENOTES
APPROPRIATE HEALTH CARE : Medical management (digoxin, diuretics, afterload reducers) either as an inpatient or an outpatient, dependent upon the patientβs condition GENERAL MEASURES : Provide general treatment for congestive heart failure SURGICAL MEASURES : If pulmonary edema, growth failure and congestive heart failure is refractive in spite of optimal medical therapy, reparative surgery should be pursued as early as possible. Repair should be especially early in children with Down syndrome (approximately 3 months). Repair should be performed before 2 years of age to avoid the continued progression of pulmonary vascular obstructive disease. Patients more than 2 years of age can undergo repair if the pulmonary vascular resistance (PVR) does not exceed 8-10 units-meters squared. At a minimum, surgical correction includes closure of the interatrial and interventricular septal defects and suspension of the medial aspects of the left and right AV valve leaflets. Pulmonary artery banding might still be a possibility. DRUG(S) OF CHOICE Digoxin, ACE inhibitors or isosorbide dinitrate plus hydralazine, furosemide, potassium supplementation . Doses for term infants . Digoxin - oral 30 MCG/kg (digitalizing), then 10 MCg/ kg/24 hrs. Adjust to maintain levels within therapeutic range - 0.5-2.0 ng/mL (0.64-2.6 nmol/L) . Captopril - 0.05-0.1 mg/kg/dose tid-qid . Isosorbide dinitrate - refer to manufacturers literature . Hydralazine - 0.75-3.0 mg/kg/dose, increase as needed to maximum of 6 mg/kg/dose . Furosemide - oral 2 mg/kg, increase as needed to maximum of 6 mg/kg . Potassium - supplement patients who require furosemide. Maintenance dose is 2-3 mEq/kg/24 hours. Contraindications: Profound systemic hypotension, worsening hypoxia and V/Q mismatch with treatment ALTERNATIVE DRUGS: Dobutamine or amrinone drips PATIENT MONITORING : . As indicated by clinical intervention and disease progression . Serial measurements of arterial oxygen content . Serial measurements of pulmonary vascular resistance PREVENTION/AVOIDANCE : Avoid hypoxic embarrassment in environments of low oxygen tension POSSIBLE COMPLICATIONS : . Refractive hypoxia secondary to progressive pulmonary vascular obstructive disease . Cyanosis . Polycythemia . Growth failure . Congestive heart failure/pulmonary edema . Complications of surgery: - Residual ventricular septal defect - Residual left ventricular to right atrial shunting - Complete AV block EXPECTED COURSE/PROGNOSIS : . PVR less than 5: - If undergoing reparative surgery, are at risk for an approximate 10% surgical mortality - The majority of those surviving realize complete relief of their symptoms and will need no further treatment . PVR between 5-13 undergoing surgery: - Perioperative mortality approaches 33% - Survivors realize functional class I or II (New York Heart Association [NYHA] classifi cation) . PVR greater than 5 who do not or can not undergo surgical intervention: - Deterioration is progressive with death ranging from 2-16 years of age
RELATED DISEASE
Not Available Disease
DISEASE
INVESTIGATION
COMPLETE BLOOD COUNT, ECHOCARDIOGRAPHY, ECG, CARDIAC DOPPLER, ARTERIAL BLOOD GASES TEST