An accurate echocardiographic evaluation of common atrioventricular canal (CAVC) requires in-depth knowledge of the wide spectrum of morphological and physiological variations in this group of anomalies. In order to evaluate the incidence and morphological distribution of AV canal defects in a Large series of patients and to define a systematic approach to the echocardiographic examination, we reviewed the echocardiograms of 206 consecutive patients with CAVC studied at Texas Children's Hospital over a 32-month period. The complete form of CAVC was most common (68.4%) and presented at an earlier age (mean +/- SD: 1.6 +/- 2.4 months). A partial AV canal (ostium primum atrial septal defect [ASD]) was found in 42 patients (20.4%) and their age at presentation was higher (9.2 +/- 10 months). Twenty-three patients (11.2%) had a transitional AV canal. Down syndrome was diagnosed in 34% of patients, the majority of whom (79%) had a complete CAVC. Associated malformations were found in 46% of patients: anomalies of the conotruncus were most frequent (18%), followed by secundum ASD (14.1%), anomalous pulmonary venous connection (11.2%), and heterotaxy syndrome (11.2%). Subaortic obstruction and mitral stenosis were less common. The AV canal was unbalanced in 14.1% of patients, with the right ventricular dominant form being more common than the left ventricular dominant form (10.7% and 3.4%, respectively). Based on. our experience, we developed a systematic, segment-by-segment approach to the echocardiographic examination in infants with CAVC. Together with detailed anatomical information, Doppler evaluation, provides crucial heb modynamic information that allows planning of surgical repair.
