[Pulsatile flow dynamics of the ductus arteriosus, thoracic aorta and pulmonary artery in patients with patent ductus arteriosus].
In 20 infants or children with an isolated or complicated patent ductus arteriosus (PDA), we qualitatively and quantitatively studied pulsatile flow dynamics of the ductus, descending thoracic aorta and pulmonary artery by means of a catheter-tip electromagnetic flow velocity probe. They were divided into four groups according to ductal shunt states as follows: 14 patients with a continuous left-to-right (L-R) shunt (Group I), three patients with a bidirectional but a dominant L-R shunt (Group IIA), two patients with a bidirectional but dominant right-to-left (R-L) shunt (Group IIB), and one patient without a significant ductal flow (Group III). In Group I, the ductal flow was pulsatile and showed continuous L-R shunting. The timing of a peak flow velocity was coincident with the peak aortic pressure at the mid-ductus, and it shifted to diastolic phase as the flow sensor approached the pulmonary end of the ductus arteriosus. In Group IIA, the peak velocity of a L-R shunt flow was located at mid-diastole and a transiently reversed R-L shunt flow was seen during systole. Two patients of Group IIB showed that the peak flow velocity of a dominantly reversed shunt was at mid-diastole, while a low grade L-R shunt flow was seen over a wide range of diastolic period. One patient of Group III who underwent operation for aortic arch interruption did not show any significant ductal flow because of a narrow PDA. In most cases of the present study, a diastolic backflow reflecting a L-R ductal shunt during diastole was demonstrated both in the descending thoracic aorta and main pulmonary artery. The peak flow velocity of the thoracic aorta was correlated with the ductal L-R shunt ratio determined by the Fick method (r = 0.46), and the diastolic regurgitant flow fraction of the thoracic aorta was increased in patients with a larger L-R shunt or with a reversed shunt. Therefore, it was suggested that a net forward flow of the thoracic aorta is reduced in these patients. On the other hand, the quantitative evaluation of a pulmonary flow during systole was found unreliable and expected to be underestimated because of the occurrence of turbulence at the site of the main pulmonary artery by the confluence of ejection stream from the right ventricle and a shunted flow from the aorta.(ABSTRACT TRUNCATED AT 400 WORDS)
D001013:Aorta, Thoracic / Q000503:physiopathology*; D001783:Blood Flow Velocity; D002648:Child; D002675:Child, Preschool; D004373:Ductus Arteriosus / Q000503:physiopathology*; D004374:Ductus Arteriosus, Patent / Q000503:physiopathology*; D006801:Humans; D007223:Infant; D011651:Pulmonary Artery / Q000503:physiopathology*; D011674:Pulse; D012039:Regional Blood Flow