J Thorac Cardiovasc Surg 1994;108:588-589
© 1994 Mosby, Inc.
Occult patent ductus arteriosus encountered during coronary artery bypass procedures
Duncan A. Killen, MD,
Jeffrey M. Piehler, MD,
A. Michael Borkon, MD,
William A. Reed, MD
Mid America Heart Institute of St. Luke's Hospital
44th at Wornall
Kansas City, MO 64111
To the Editor:
During a 21-year period ending December 31, 1991, more than 14,000 coronary artery bypass procedures were performed at the Mid America Heart Institute. In four patients a patent ductus arteriosus (PDA), which had not been suspected before the operation, was discovered during the operation. In each case, preoperative evaluation (including left ventriculography and coronary arteriography) had not aroused suspicion of a PDA. Furthermore, the presence of the PDA was not suspected during the operation until cardiopulmonary bypass was begun, but became manifest only after induced cardiac arrest when distention of the pulmonary artery and left side of the heart became evident. Without exception, there was some delay in considering the presence of a PDA as the cause of the inability to adequately decompress the heart.
Once the presence of a PDA was suspected, dissection was made between the distal aortic arch and the left pulmonary artery, with the patient supported by cardiopulmonary bypass. A PDA was identified and isolated in each patient. Patency of the ductus was confirmed by palpation of the pulmonary artery opposite the entry of the ductus, where a soft thrill, which disappeared with occlusion of the ductus, was noted. Additionally, the heart could be decompressed adequately with temporary ductal occlusion. In each instance, the ductus was ligated and the operative procedure was completed as planned. A summary of the clinical findings and operation performed in these four patients is shown in 
Table I. No patient had any sequelae of the PDA or its treatment: specifically there was no intraoperative hemorrhage or left vocal cord paresis.
Almost certainly, patients who reach adulthood with an asymptomatic, occult PDA have restricted flow though a small ductus. In the patients observed in this study the PDA was small and must have been of minimal hemodynamic significance. Recent refinements in diagnostic techniques, more especially the use of color flow Doppler echocardiography, have revealed that the persistence of PDA into adulthood and old age is probably more common than was previously suspected. 1 Tunick and Kronzon 2 reported that an undiagnosed PDA was found in seven individuals during the performance of 8774 echocardiograms in adult patients referred because of suspected or known cardiac disease. In each instance the PDA was diagnosed only when the color flow Doppler echocardiography technique was used.
In general, interruption of a PDA in an adult has been fraught with technical difficulties because of vessel wall deterioration and calcification, aneurysm formation, or associated pulmonary hypertension. 3,4 Perhaps the presence of a low-flow PDA without associated pulmonary hypertension minimized these degenerative changes in our four patients. Also, manipulations of the PDA were performed with a controlled systemic blood pressure because the patients were supported by cardiopulmonary bypass. 4 Simple ligation was performed with a large silk ligature (in three patients) and an umbilical tape (in one patient) without any technical complications. Certainly other techniques, such as transpulmonary artery suture closure of the ductus under reduced systemic flow, might have been used; however, simple ligation of such a PDA seems to be a safe and definitive plan of management.
References
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