Objective: The common arterial trunk usually has a balanced origin from both right and left ventricles overriding a ventricular septal defect. The trunk occasionally originates predominantly, or even exclusively, from either ventricle, making the size of the ventricular septal defect an important factor in surgical repair.
Methods: We examined 56 autopsy specimens and reviewed another series of 12 consecutive patients with the malformation. Truncal origin was categorized as 1 of the following 5 types: exclusive origin from either the right or left ventricle, predominant origin from either ventricle, or balanced origin. We measured the size of ventricular septal defect ("width" and "depth") in specimens for any correlation with truncal origin.
Results: Balanced origin was seen in approximately one half of cases in both autopsy and clinical series. Predominantly or exclusively right ventricular origin was more prevalent than left ventricular origin in autopsy series (40% vs 9%, respectively), but such predilection was not observed in clinical series (both 25%). The more the truncal valve was committed to the right ventricle, the smaller was the "width" of the ventricular septal defect (predominant and exclusive vs balanced origin; both P < .0001), with similar tendency in the "depth." In 1 heart with extreme right ventricular origin, the defect was slit-like.
Conclusion: Origin of the truncal valve demonstrated a morphologic spectrum and correlated with the size of ventricular septal defect that was the main or even sole exit from the left ventricle in hearts with right ventricular origin. Truncal origin, therefore, requires recognition to optimize surgery.