Comparison of healing in fresh and preserved arterial allografts in the dog

Limb salvage after aneurysmal degeneration of a cryopreserved vein allograft: Searching the autologous veins of the arm is worth the effort

CLINICAL DATA

We hereby report a case of limb salvage involving a 64-year-old man who was hospitalized with ischemic foot ulcers for two months. Endarterectomy with patching and stenting of the left iliofemoral artery failed. A composite bypass of two segments of the endarterectomized superficial femoral artery and a cryopreserved saphenous vein graft was implanted one week later. On day 4 postoperatively, an infection (Staphylococcus epidermidis and Pseudomonas aeruginosa) was treated empirically with antibiotics. Four months later, the femoro-tibial bypass thrombosed and the patency was restored by thrombolysis. The aneurysmal cryopreserved vein was excised. Iterative complications followed and final success was attained after implantation of autologous cephalic and basilic veins. Four years later, this femoro-tibial is still patent.

PATHOLOGICAL ANALYSES

After a gross observation, the explant was dissected and the most significant sections were processed for histology, followed by analyses in scanning electron microscopy, light microscopy and transmission electron microscopy.

RESULTS

The explanted specimen showed a smooth flow surface proximally but a severe distortion distally, with an accumulation of poorly organized mural thrombi. The wall of the arterialized vein was accompanied with an important inflammatory reaction. The degradation of the collagen structure was evidenced in TEM. The fibrils of collagen were still individualized but were fragmented and did not display parallelly. The regular banding was preserved. The presence of Pseudomonas aeruginosa was shown inside the wall of the homologous vein.

COMMENTS

In case of sepsis, the most aggressive antibiotic treatments cannot fully eliminate the bacteremic colonizations within the wall of an alternative conduit. The cephalic and basilic autologous veins are proved to be preferable in absence of the autologous saphenous vein. The amputation was prevented and four years later the bypass is still patent. This is an outstanding result based upon the comorbidities of the patient. The most aggressive harvesting shall be recommended. This patient represented a considerable challenge and the clinical result is highly gratifying: the search for the autologous cephalic and basilic veins proved to be worth the effort.

The seven-year' secondary patency of a fresh arterial allograft in the femorocrural position in a heart transplant recipient

Critical limb ischemia in patients with diabetes at the organ complication stage represents a considerable challenge in vascular medicine. Because of the complexity of the disease and the often symmetric involvement of both lower limbs, a discrepancy between suitable vascular conduit availability and the actual requirement can occur: notably, the prevalence of multilevel and diffuse arterial disease often limits the possibilities of endovascular treatment, and, in surgical cases, frequently prohibits the effective use of prosthetic material. In our patient with bilateral critical limb ischemia and previous coronary artery bypass graft followed by cardiac transplantation, only one great saphenous vein remained available. That was used in its entirety to salvage one limb as a sequential femorocrural bypass. A similar surgical procedure with a fresh arterial allograft retrieved from a deceased donor was performed on the other extremity . ABO compatibility as well as the chronic immunosuppressive therapy in a heart transplant recipient may have contributed to the favorable long-term clinical outcome of the allogeneic arterial reconstruction.

Delayed administration of FK 506 is sufficient to suppress acute rejection changes after aortal transplantation in rats

Arterial allografts are used now-a-days as a modality in the treatment of vascular prosthesis infections. Prolonged administration of immunosuppressive drugs seemed to be essential for long-time patency rates of alloarterial vascular reconstructions. Nevertheless, the use of immunosuppressives if there exist an acute infection is controversial. The experimental work described herein studied effects of a delayed low-dose FK 506 administration on the development of acute rejection changes 30 days after aortal transplantation in rats. The response of the recipient's immune system to aortal wall antigens of the donor in the field of no immunosuppression resulted in an intimal proliferation and its infiltration by immunocompetent cells of the recipient, necrosis of medial smooth muscle cells, including deposition of immunoglobulins, and a massive adventitial infiltration of CD4 and CD8 positive cells. On the other hand, all the principal histological signs of rejection listed above were suppressed by FK 506 administration, no matter whether the immunosuppressive was administered on day 0 or day 7 after the transplantation.