Changes in aortic function after interposition of a tubular graft in the descending porcine thoracic aorta

The objective of the study was to investigate the alterations of aortic function after interposition of a tubular graft in the descending porcine thoracic aorta. Eight healthy Landrace pigs were subjected to thoracotomy under sterile conditions. A 5-cm-long segment of descending thoracic aorta was replaced with a Dacron graft. Pulse wave velocity (PWV) was measured using simultaneous recordings of electrocardiogram and Doppler pressure waveforms, which were received from right carotid and femoral arteries. Then, the recordings were fed to a computer for analytical estimation of PWV in several occasions: right after the interposition (D0), and after 15 (D15) and 30 (D30) days time. Euthanasia was performed after the D30-recordings and the aortic graft area was removed. "Before graft" (BG) as well as "after graft" (AG) aortic regions were examined under light microscopy in order to determine the aortic thickness (T) and number of lamellar units (LU). Eight sham-operated pigs were used as controls. The results showed that PWV decreased as soon as the graft interposition took place and was maintained, until the end of experiment (P < 0.05). Aortic wall thickness was increased both at pregraft and postgraft areas (P < 0.05), and LUs were also increased at the same regions. It is concluded that the interposition of a tubular graft in the descending thoracic aorta resulted in a decrease in PWV, which may improve left ventricular performance and enhance myocardial perfusion, due to a delay in the arrival of the reflecting diastolic wave.