Surgical mortality for uncomplicated ostium primum defects in experienced centers is 2%; for uncomplicated cases of complete atrioventricular canal, 4% or less.
Some of the most troublesome filled-capsule defects occur in the capsule closing process, and are termed splits, telescoped capsules, folds and cap tucks.
The electrocardiogram often shows sinus tachycardia or atrial fibrillation, ventricular arrhythmias, left atrial enlargement, and sometimes intraventricular conduction defects and low voltage.
