The Journal of Thoracic and Cardiovascular Surgery, Vol 86, 294-299, Copyright © 1983 by The American Association for Thoracic Surgery and The Western Thoracic Surgical Association
Parallel growth of rectus sheath grafts and recipient aorta. Critical role of graft tissue preservation
TV Bilfinger, PE Beere, C Sanderson, S Glagov and CE Anagnostopoulos
Previous experimental studies revealed striking similarities in mechanical
properties of host aortic tissue and rectus sheath inserted as an aortic
graft, as well as enlargement of some of the grafts. We have now evaluated
the capacity of rectus sheath grafts to keep pace with aortic growth and
investigated the role of tissue preservation in determining the ability of
such grafts to maintain suitable dimensions. Autologous rectus sheath
grafts were substituted for thoracic aortic segments in 15 puppies, 8 weeks
of age. Nine grafts were inserted with careful attention to tissue
preservation (live grafts), but in six experiments, cells were killed and
tissues fixed by freezing and thawing in acetone before graft implantation
(devitalized grafts). Grafts were fixed in situ by controlled pressure
perfusion and examined 1, 2, and 3 months after implantation. Over the 3
month experimental interval, body weight increased from 2.0 +/- 1 pounds to
25.0 +/- 2.5 pounds, and as is characteristic for the period of maximum
growth rate for the animals. Total thoracic aortic length increased 41.2%
+/- 6.1% and aortic diameter, 30.0% +/- 3.1%, during this time. Growth rate
of the total thoracic aortic length during the first month was greater for
the devitalized graft group, but aortic length was the same for both groups
at 3 months. The live grafts increased 42.3% +/- 12.0% in length and 27.3%
+/- 3.0% in diameter, i.e., to the same degree as the aorta, whereas the
devitalized grafts showed only slight increases in length and diameter
(2.1% +/- 2% and 5.3% +/- 5%, respectively). The live rectus sheath grafts
were augmented and largely replaced by a newly formed, layered
fibrocellular structure, 45.8 +/- 25.8 mm3 in volume, whereas in the
devitalized grafts more of the original rectus sheath persisted and only a
minimal amount of organized connective tissue sheath was formed (volume
18.7 +/- 8.9 mm3). In addition, cellularity was much greater in live grafts
than in devitalized specimens (990.9 +/- 186.8 cells/mm2 and 423.6 +/-
124.7 cells/mm2, respectively). All of the grafts were lined by
endothelium. These findings indicate that autologous rectus sheath aortic
grafts may be used to provide channels which keep pace with aortic
dimensions during the period of maximum growth, provided that the graft
tissue is viable on implantation. Long- term durability of such grafts may
also depend on tissue preservation.
