A new stretch for Gor‐Tex™

Abstract

This study demonstrates the capability of over expanding the nominal diameter of stretch Gor-Tex TM (PTFE) tubular vascular grafts used for systemic to pulmonary shunts in infants. Until this article, most interest and published work on re-expansion of thin walled GorTex TM in the congenital population concerned large stents covered with Gor-Tex TM in the setting of larger vessels (aorta or ''Fontan'' channels) and the ability to expand these covered stents to an even larger diameter after several or more years to accommodate the growth of a patient. Likewise, previous information on the dilation of shunts was concerned with the relief of acquired stenosis within those shunts.The in vitro bench testing in this study documented that by implanting an intravascular stent mounted on a balloon, which is larger in diameter than the graft, the native Gor-Tex TM tubular grafts could be stretched in diameter up to 40 to 45% larger than the nominal diameter of the graft.The investigators also documented, the safety of the ''over dilation'' by demonstrating that even when high pressure (up to 18 Atms), larger balloons (balloons larger than the nominal diameter plus the 40-45% expected stretched diameter) were used, the grafts still only reached the maximum increase of 40-45% over their nominal diameter. Of even greater importance, while the oversized balloons did not increase the diameter of the grafts any more than the 40-45%, the significant over dilation of tubular grafts did not tear or split the grafts.Clinically, the over-dilation of the graft technique was used in 10 young patients. A total of 14 stents were placed in 11 Gor-Tex TM grafts. All stent dilation/ implants increased the diameter to 1 mm greater than the nominal diameter of the graft and produced an increased flow to the pulmonary bed with a concomitant increase in systemic saturations in all patients. Five of ten patients maintained enough clinical improvement to survive for as long as 6 months and up to 5 years after the tube graft over expansion, which in turn allowed them to undergo more definitive surgery without any other intervening intervention. Within 10.2 months after the initial over expansion of their grafts, four patients did deteriorate clinically with three of four grafts requiring re-stenting and one, an angioplasty of the previously stented tubular graft.In addition to the encouraging new information from the study, the authors supplied a plethora of valuable technical advice, not the least of which was that the procedure really required two pairs of knowledgeable hands to accomplish the complex manipulations in traversing the circuitous anatomy to the orifice of a shunt and safely dilating and implanting the stent accurately into the graft.The results from the in vitro study, along with the small clinical series of patients suggest that the use of a Gor-Tex TM tubular grafts are preferable to a classic native subclavian to pulmonary artery shunt in small infants as the ability to safely over dilate the GorTex TM tubular grafts allows a re...