Inadvertent interruption of descending thoracic aorta on cardiopulmonary bypass during repair of a ventricular septal defect and interruption of a patent ductus arteriosus: Its recognition, consequences, and prevention

Abstract

PATENT DUCTUS ARTERIOSUS (PDA) is commonly closed through a left thoracotomy. The sizes of the PDA, pulmonary artery (PA), and aorta can be quite similar, and to identify the ductus, the surgeon can test occlude the vessel to be ligated.1 Accidental interruption of the ascending aorta, pulmonary artery (PA) or descending thoracic aorta (DTA) can lead to devastating results. Placement of the pulse oximeter on a lower extremity and the blood pressure cuff on the right arm allow the anesthesiologist to assess flow in the ascending and descending aorta. Occlusion of the PA is characterized by a decrease in the arterial saturation and a decrease followed by an increase in end-tidal carbon dioxide tension.1 These methods of identification of the vessel test occluded are dependent on pulsatile blood flow and intermittent positive-pressure ventilation. During simultaneous repair of intracardiac lesions and interruption of PDA through a midsternotomy,2 PDA is ligated either before3 or after4 initiation of cardiopulmonary bypass (CPB). PDA is identified by its anatomic location, by its relationship with the left pulmonary artery and the undersurface of the aorta4 and by identifying its opening from within the pulmonary artery.2 On CPB, collapse of the PA and rise in the mean arterial pressure after ligation are the indirect features that suggest that the vessel occluded is the PDA. The monitoring used during PDA ligation through a left thoracotomy to prevent accidental ligation of a vessel other than the PDA is less useful during CPB because of the loss of pulsatile blood flow and discontinuation of ventilation. A case of fatal accidental ligation of DTA in a child who underwent ventricular septal defect (VSD) repair and PDA interruption under CPB is described.