Supplemental oxygen controls cellular proliferation and anastomotic intimal hyperplasia at a vascular graft-to-artery anastomosis in the rabbit.

PURPOSE: The purpose of this study was to determine whether the administration of 40% supplemental oxygen (O ( 2) ) will decrease cellular proliferation and intimal hyperplasia (IH) at a prosthetic vascular graft (PVG)-to-artery anastomosis. METHODS: Twenty New Zealand white rabbits underwent placement of a 3-mm polytetrafluoroethylene graft in their infrarenal aorta. Four groups of five rabbits were placed either in a normoxic (21%) environment or in a 40% supplemental O ( 2) environment for 7 or 42 days. Twenty-four hours before the rabbits were humanely killed for aortic graft harvest, BrDU (5-bromo-2'-deoxyuridine) was injected into the rabbits intraperitoneally. Image analysis (Bioquant) morphometrics were used to measure cells with BrDU staining and intimal areas at the distal anastomosis. Cellular proliferation is defined as positively staining BrDU cells divided by all cells in the artery wall. IH is reported as a ratio between the intimal area and the medial area to standardize the varying aortic size and degree of aortic fixation among rabbits. The Student t test was used to compare cellular proliferation and IH between control and O ( 2) -treated rabbits. RESULTS: Cellular proliferation in the intima at 7 days was significantly reduced in the O ( 2) -treated animals (1.7% +/- 1%) versus the control animals (28.6% +/- 3%) ( P =.0001). The cellular proliferation in the intima at 42 days returned to preoperative levels in the O ( 2) -treated group (0.15%) and in the control group (0.11%) ( P = not significant). IH at 7 days was minimal, and no difference between the O ( 2) -treated group (0.017 +/-.006) and the control group (0.009 +/-.03) ( P = not significant) was found. IH was significantly reduced at 42 days in the O ( 2) -treated animals (0.031 +/-.012) when compared with the control animals (0.193 +/-.043) ( P =.006). CONCLUSIONS: Supplemental O ( 2) (40%) significantly reduces cellular proliferation and IH at the distal anastomosis of a PVG-to-artery anastomosis in the rabbit model.

Revascularization and quality of life for patients with limb-threatening ischemia.

Traditional outcomes following revascularization for chronic critical limb ischemia consider limb retention and hemodynamic results. Health-related quality of life is not measured. This study was undertaken to determine if surgery for chronic critical limb ischemia improves health-related quality of life. Forty-six patients undergoing revascularization (anklebrachial index <0.4 for nondiabetics, ankle-brachial index <0.6 for diabetics and rest pain or nonhealing ischemic ulcers) completed pre- and postoperative Short-Form 36 questionnaires, which were used to assess health-related quality of life in patients undergoing arterial reconstruction for chronic critical limb ischemia. Patients reported a mild improvement in functional status postoperatively, and overall low health-related quality of life. Health-related quality of life is slow to show progress following revascularization. Health-related quality of life should become an important outcomes end point.

Association of artery wall hypoxia and cellular proliferation at a vascular anastomosis.

BACKGROUND: We hypothesize that arterial wall hypoxia incites the pathologic formation of intimal hyperplasia at an artery anastomosis. We have determined from previous studies performed in our laboratory, the oxygen tension profiles of the artery wall at various times after vascular anastomosis. The purpose of this study is to determine the rate of cellular proliferation at an artery anastomosis when the artery wall is most hypoxic. MATERIALS AND METHODS: Expanded polytetrafluoroethylene (ePTFE) grafts were placed end to end in the infrarenal aorta of 27 New Zealand white rabbits. The anastomotic aortic wall oxygen (O(2)) tensions were measured with an O(2) microelectrode in rabbits 0, 7, 14, 28, and 42 days after surgery. O(2) tensions were also measured in 4 control rabbits for comparison. 5-Bromo-2'-deoxyuridine (BrDU) was injected intraperitoneally 24 h prior to rabbit sacrifice. After O(2) tension measurements, the rabbits were sacrificed and the aortic grafts were harvested. Bioquant morphometrics was used to measure cells with BrDU counterstaining and intimal thickness in 17 rabbits: in control (n = 4), Day 0 (n = 4), 7 (n = 5), and 42 (n = 4). Student's t test was used to compare O(2) tensions, cellular proliferation, and intimal hyperplasia between days. RESULTS: The pO(2) levels at the outer layers of the aorta, 1 mm distal to the distal aortic graft anastomosis, were 61.0 +/- 2 (+/-SE) mm Hg for controls, 19.8 +/- 1 mm Hg for Day 7 (P < 0.0001), 19.0 +/- 1 mm Hg for Day 14, 39.2 +/- 1 mm Hg for Day 28, and 58.5 +/- 1 mm Hg for Day 42 aortic grafts. BrDU-staining ratios in the intima were significantly higher in the Day 7 aortic grafts, 28.6 +/- 3%, versus BrDU-staining ratio, 1.4 +/- 1%, in Day 42 aortic grafts (P < 0.0002). CONCLUSIONS: Cellular proliferation is highest at Day 7 when the artery wall is most hypoxic and returns to baseline as O(2) tensions normalize.

Comparing patency rates between external iliac and common iliac artery stents.

PURPOSE: Placement of intraluminal stents in the common iliac artery (CIA) and external iliac artery (EIA) has become an accepted therapy for treating localized arterial stenoses. The purpose of this study was to compare anatomic patency rates of stents placed in the EIA and CIA for occlusive disease. METHODS: A radiologic computer database was used to identify 69 consecutive male patients at the Minneapolis Veterans Affairs Medical Center from February 1, 1993, through January 31, 1999, who underwent placement of 98 stents (82 Wallstents and 16 Palmaz stents) for physiologically significant iliac artery occlusive disease and varying degrees of chronic limb ischemia. Patients were followed up with surveillance duplex ultrasound scanning examinations 1 day after procedure, 3 months after procedure, and then at 6-month intervals after stent placement. Follow-up angiograms were performed for patients with duplex ultrasound scans that revealed velocities greater than 300 cm/s. Patient risk factors, iliac artery runoff, concomitant outflow procedures, and anatomic patency rates were compared between patients receiving EIA stents and those receiving CIA stents. RESULTS: The mean age for the EIA stent group was 69 +/- 1 years versus 66 +/- 1 years (P =.03) for the CIA stent group. Mean follow-up was 21.4 +/- 2.1 months (+/- SE) for all patients. Patients with EIA stents had more ischemic lower limbs when compared with patients who had CIA stents (P =.05). No differences were found between groups in risk factor analysis (P = not significant). Lesion lengths were similar between groups: EIA, 4.6 +/- 0.6 cm, and CIA, 5. 3 +/- 0.8 cm (P = not significant). The following differences were noted on primary patency rates (EIA group vs CIA group): 1 year (93% vs 88%), 2 years (91% vs 85%), and 3 years (90% vs 78%) (Cox proportional hazards; P =.13). CONCLUSIONS: Anatomic patency rates for EIA and CIA stents appear to be similar despite the fact that patients with EIA stents were older and had more ischemic limbs compared with the patients who had CIA stents.

Use of a noncontact radiant heat bandage and Staphylococcus aureus dermal infections in an ovine model.

Diabetic foot wounds are difficult to manage due to relative tissue ischemia and high rates of soft tissue infection. One potential treatment modality is the application of local radiant heat to promote wound healing and control infection. However, there are concerns that local heat will spread rather than control infection. We determined in this study the effect of a noncontact radiant heat bandage in controlling an ischemic soft tissue infection. Bilateral 10 x 15 cm dermal flaps were created in 15 adult range sheep. The flaps were inoculated intradermally with 107 Staphylococcus aureus in 3 separate areas. The control flap was left open to air, while the treatment flap was covered with a noncontact radiant heat bandage and heated to 38 degrees C for three 1-hour periods separated by two 1-hour nonheating periods daily. After 10 days, both dermal flaps were harvested and sent for quantitative bacteriology. Due to operative complications, 12 of 15 sheep completed the study. The heated flap temperature was significantly higher 39.2 +/- 0.5 degrees C (+/- SE) vs. the control flap 36.1 +/- 0.1 degrees C (p < 0.00001) and bacterial counts were significantly smaller in the heated flap (median 1.0 x 107 colony-forming units per gm tissue) when compared to the control flap (median 7.5 x 107) (p = 0.001). This study shows the use of a noncontact radiant heat bandage controls ischemic soft tissue infections in an ovine model.

Staged resection or primary anastomosis for obstructing lesions to the left colon.

The management of obstructing left-sided colonic and rectal lesions has traditionally been by a staged procedure. The introduction of 'on-table lavage', has made primary resection and anastomosis of the large bowel feasible for patients presenting as emergencies. We have studied the perioperative course of 28 patients who presented with left colonic obstruction to determine whether primary anastomosis conferred additional morbidity. The patients ranged in age from 29 to 89 years (mean 66 years) at presentation. The ASA status of patients was comparable in both groups (Table 1). Fourteen patients underwent resection, on-table lavage, and primary anastomosis (PA) and 14 a Hartmann's procedure (HP). The mean operative time for the PA procedure was 200 minutes compared to 110 minutes for the HP group. There was no significant difference in the postoperative complication rate nor mean hospital stay rate for the primary procedures between the two groups. There was no clinical anastomotic leak in patients undergoing primary anastomosis. However secondary surgery for patients undergoing colorectal reconnection conferred added morbidity for patients who had a HP. We conclude that resection, on-table lavage, and primary anastomosis is safe in the management of left-sided colonic obstruction and in most cases is the treatment of choice.