Vascular grafts after replacement of the ascending and descending aorta in 562 cases: When do Dacron grafts stop growing?

Objective: The tendency of vascular Dacron grafts to expand after placement in the ascending and descending thoracic aorta has been noted. However, the time-course of this expansion has not yet been described.

Methods: Two or more CT-studies were obtained during routine postoperative surveillance in patients with Dacron grafts implanted to replace diseased aortic segments. Postoperative CT-scans (N>2000) were digitized to evaluate the entire thoracic aorta, the median diameters of 562 Dacron grafts (Ø: 20–32mm) in the ascending and descending aorta were calculated.

Results: In scans obtained ≤7 days after implantation, the graft diameters increased from the manufacturer's measurement by >20% (p<.0001) in the ascending (n=169; IQ-range: 11–21%), and 15% (p<.0001) in the descending aorta (n=79; IQ-range: 12–25%). From an initial scan within 30 days to at least one other within 18 months after implantation, ascending grafts dilated further (p=0.003), at a median rate of 3.3%/year (n=154; IQ-range: 2–7%). Descending grafts dilated less markedly: 2.6%/year (p=0.06;n=94; IQ-range: 4–7%). After 18 months, graft expansion diminished to zero.

Fig. 1 Follow-up of Dacron Grafts, Digitized CT-scan Follow-up of Dacron Grafts

Conclusions: Significant expansion of vascular Dacron grafts within 18 months after implantation should be anticipated when selecting grafts for aortic valve-sparing procedures to prevent development of regurgitation, and, for endovascular repair of thoracoabdominal aneurysms, to prevent development of Type-III-endoleaks in the projected landing zone.