Complete replacement of tracheal epithelia by the host promotes spontaneous acceptance of orthotopic tracheal allografts in rats.

BACKGROUND: Tracheal immunogenicity has been controversial. Although replacement of allotracheal epithelia by the host epithelia has been reported in rat orthotopic tracheal grafting, the immunological effect of epithelial replacement is still uncertain. METHODS: We performed orthotopic tracheal grafting of nine cartilage rings in the following groups: 1, Lewis --> Lewis (n = 30); 2, ACI --> DA (n = 25); 3, Lewis --> F344 (n = 23); 4-A, DA --> Lewis (n = 41); 4-B, DA --> Lewis with tacrolimus therapy (1 mg/kg/d for 10 days) starting from the day of the operation (n = 31); 4-C, retransplantation of DA allografts to secondary naive Lewis rats 10 or 15 days after primary grafting (n = 11); 4-D, DA --> Lewis with tacrolimus therapy starting from postoperative day 10 (n = 6). Survival times and histopathology were assessed. Epithelial replacement was evaluated by immunohistochemistry. RESULTS: All rats survived in groups 1, 2, and 3. Even in the fully histoincompatible group 4-A, survival ratio on day 120 was 15%. Epithelial replacement was in progress on day 10 in this group. However, all tacrolimus-treated rats died by day 54 and epithelial replacement did not occur on days 30 and 50 in group 4-B. In group 4-C, retransplantation after complete epithelial replacement increased the long-surviving rats. In group 4-D, all rats receiving tacrolimus therapy after complete epithelial replacement survived over 120 days. CONCLUSIONS: These results suggest that complete replacement of tracheal epithelia by the host promotes spontaneous acceptance of orthotopic tracheal allografts in rats.

Reduction of ischemic spinal cord injury by dextrorphan: comparison of several methods of administration.

OBJECTIVES: We investigated the effect of dextrorphan, an N -methyl-D -aspartate receptor antagonist, on the reduction of ischemic spinal cord injury and the safe clamping time after various methods of administration. METHODS: Spinal cord ischemia was induced in New Zealand White rabbits by infrarenal aortic clamping and animals were divided into 5 groups. Group A (n = 15) received simple clamping. Groups B (n = 20) and C (n = 35) received dextrorphan pretreatment (10 mg/kg), followed by continuous intravenous or intra-aortic infusion (1 mg/min), respectively. Group D (n = 25) received the same dextrorphan pretreatment and bolus intra-aortic injection at clamping (1 mg per minute of clamping time). Group E (n = 15) received bolus intrathecal injection of dextrorphan (0.2 mg/kg). Each dextrorphan-treated group had a small group of control animals (n = 5). The neurologic status was assessed by the Johnson score (5 = normal, 0 = paraplegic) 48 hours after unclamping, and animals were put to death for histopathologic examination. RESULTS: All dextrorphan-treated groups showed better neurologic function than the respective control animals (P <.001 vs groups B, C, and D; P =.014 vs group E). The order of efficacy of dextrorphan (as revealed by the average of neurologic status) was as follows: group C > group D (P =.017, after 50 minutes of clamping), group D > group B (P =.014, after 45 minutes of clamping), and group B > group E (P <.001, after 40 minutes of clamping). Histopathologic findings did not necessarily correspond with hind-limb neurologic function. CONCLUSIONS: Dextrorphan reduced the physical findings associated with ischemic spinal cord injury, and continuous intra-aortic infusion prolonged the safe clamping time significantly more than delivery by other routes.

Experimental study on the effect of antegrade cerebral perfusion on brains with old cerebral infarction.

OBJECTIVE: Patients with old cerebral infarction who undergo aortic arch operations are susceptible to postoperative neurologic dysfunction. To verify such susceptibility, we performed this experimental study. METHODS: A cerebral infarct model was created in mongrel dogs by means of injection of cylindrical silicone embolus through the internal carotid artery. The dogs that had obvious neurologic deficits 1 day later and survived for 4 weeks or more were included in the cerebral infarct model. One month after cerebral infarction was induced, deep hypothermia and selective cerebral perfusion were used in 14 mongrel dogs (infarct group, n = 7; control group, n = 7). During this procedure, serum glutamate concentration and venous-arterial lactate difference were measured. Histopathologic study of the brain was also performed. RESULTS: Changes in venous-arterial lactate difference in both groups were almost similar, except in the rewarming phase. At 32 degrees C during rewarming, the venous-arterial lactate difference in the infarct group was significantly higher than that in the control group (P =.006). Although pre-cooling concentrations of serum glutamate were similar in both groups, the values in the infarct group at the end of rewarming were significantly higher than those in the control group (P =.046). On histologic examination, the presence of old cerebral infarction with gliosis was confirmed in the infarct group, but neither new cerebral infarction nor destruction of the blood-brain barrier was found. CONCLUSION: We observed an accelerated anaerobic metabolism and an increased extracellular glutamate release in the infarct group. The brain with old cerebral infarction is more susceptible to ischemia during arch operation than noninfarcted brain.

New cerebral monitoring using optical topography during total arch replacement.

We investigated the levels of oxygenation in the extended cerebral regions, including the middle cerebral artery region, using optical topography in two patients who underwent total arch replacement assisted by selective cerebral perfusion. During the cooling phase, the oxyhemoglobin levels were almost homogenous. During selective cerebral perfusion, when 18 French and 16 French cannulae were used for the innominate and the left common carotid artery respectively, the oxyhemoglobin levels in the left hemisphere were consistently greater than those in the right. After the 16 French cannula was replaced with a 14 French in the left common carotid artery, then no difference between the hemispheres was found. During the rewarming phase, the increase in the oxyhemoglobin levels in the parietal region was consistently more delayed than that in the temporal region, in both patients. Optical topography might be useful for more precise monitoring of the cerebral circulatory status during an aortic arch operation.

Aortic regurgitation with dilation of ascending aorta and right coronary artery occlusion by a rudimentary aortic cusp.

Occlusion of a coronary artery ostium, especially that of the right by an aortic cusp, is a rare congenital anomaly. We had the experience of dealing with an adult patient with aortic regurgitation due to a rudimentary aortic cusp that also occluded the right coronary ostium. We performed composite graft replacement because the patient also had coexistent dilation of the ascending aorta. Postoperative course was uneventful.

Simultaneous total arch replacement and abdominal aortic surgery.

It is common to encounter patients with coexisting aortic arch aneurysm and abdominal aortic lesions. We conducted simultaneous total arch replacement and abdominal aortic surgery in 3 patients having such lesions. Mean operative time was 511 minutes and no in-hospital mortality occurred. Postoperative respiratory failure was observed in an 80-year-old patient who recovered and all three patients were discharged in good condition. No other postoperative complication was seen. Simultaneous total arch replacement and abdominal aortic surgery may thus offer advantages to patients with such double aortic lesions if it can be conducted safely.

Surgical treatment of annuloaortic ectasia with coronary aneurysm and fistula.

Annuloaortic ectasia associated with a giant aneurysm of the left coronary artery and a coronary artery fistula is extremely rare, and it is difficult to decide how to repair this complex lesion. The cause of the huge aneurysm of the left coronary artery in our patient was thought to be cystic medial necrosis, the coronary artery fistula, or both. The surgical management of this extremely rare pathological combination is described.

Improved results of atherosclerotic arch aneurysm operations with a refined technique.

OBJECTIVE: We sought to analyze the postoperative hospital mortality and postoperative neurologic dysfunction in patients who had total arch replacement for atherosclerotic arch aneurysms using our recent refined technique. METHODS: Between June 1997 and April 2000, 50 consecutive patients underwent total arch replacement with an aortic arch branched graft for atherosclerotic arch aneurysms. Their mean age was 71 +/- 7 years (range, 57-87 years). Forty-eight (96%) patients were operated on electively, and the remaining 2 (4%) were operated on an emergency basis because of rupture of aneurysm. All operations were performed with hypothermic extracorporeal circulation, selective cerebral perfusion for cerebral protection during aortic arch repair, and systemic circulatory arrest during distal graft anastomosis. A total of 19 concomitant procedures were done in 17 patients. Mean selective cerebral perfusion time was 78.1 +/- 16.5 minutes. RESULTS: Overall in-hospital mortality was 2% (95% confidence intervals, 0%-5.9%). On univariable analysis, permanent neurologic dysfunction was the only risk factor for in-hospital mortality. Postoperative temporary and permanent neurologic dysfunctions were 4% (95% confidence intervals, 0%-9.4%) and 4% (95% confidence intervals, 0%-9.4%), respectively. On univariable analysis, cardiopulmonary bypass time was the only risk factor for temporary neurologic dysfunction, and history of cerebrovascular disease was the only risk factor for permanent neurologic dysfunction. There was no significant correlation between selective cerebral perfusion time and temporary and permanent neurologic dysfunction. CONCLUSION: Integrated cerebral protective effect of antegrade selective cerebral perfusion and total arch replacement with an aortic arch branched graft could substantially reduce in-hospital mortality and postoperative neurologic dysfunction in patients with atherosclerotic arch aneurysms.

Total arch replacement using aortic arch branched grafts with the aid of antegrade selective cerebral perfusion.

BACKGROUND: We report our clinical experience with total arch replacement using aortic arch branched graft in an attempt to determine the independent predictors of both in-hospital mortality and neurologic outcome. METHODS: We studied 220 consecutive patients who underwent total arch replacement using aortic arch branched graft between May 1990 and June 1999. All operations were performed with the aid of hypothermic extracorporeal circulation, antegrade selective cerebral perfusion, and open distal anastomosis. RESULTS: The overall in-hospital mortality rate was 12.7%. Multivariable analysis showed independent determinants of in-hospital mortality to be chronic renal failure, long pump time, participation in early series, and shock. Postoperative permanent neurologic dysfunction was 3.3%. On multivariable analysis, old cerebral infarct and pump time were independent determinants of permanent neurologic dysfunction. The selective cerebral perfusion time had no significant influence on in-hospital mortality or neurologic outcome. The 5-year survival rate including in-hospital deaths was 79% +/- 6%. CONCLUSIONS: Selective cerebral perfusion allows increased ease of performance of total arch replacement, a complex and time-consuming procedure, and helps reduce periprocedural mortality and morbidity in patients with aortic arch aneurysm and those with acute aortic dissection.

Surgical treatment of recurrent abdominal aortic aneurysm in a patient with systemic lupus erythematosus.

Reports of true abdominal aortic aneurysms (AAAS), especially those due to severe inflammation, in patients with systemic lupus erythematosus (SLE) are very few in number. However, we had the experience of surgically treating a recurrent AAA due to severe inflammation found in a patient with SLE. The recurrence took place after an earlier operation for an infrarenal AAA and involved the left renal artery. In both situations, the previous infrarenal aaa and the recurrence, the aneurysms demonstrated more rapid growth and more irregularities in shape. Etiology of the AAA might be a combination of Takayasu's arteritis and SLE because the two entities appeared to have overlapped.

Extended total arch replacement for acute type a aortic dissection: experience with seventy patients.

OBJECTIVE: We sought to report the clinical experience with extended total arch replacement for acute type A aortic dissection and to determine the factors that influence early mortality, late survival, and late reoperation. METHODS: Between December 1988 and August 1998, 70 patients underwent emergency graft replacement of both the ascending aorta and the total aortic arch for acute type A aortic dissection. All operations were performed with hypothermic extracorporeal circulation, selective cerebral perfusion for cerebral protection during aortic arch repair, and open distal anastomosis. Concomitant procedures included aortic valve resuspension in 18 patients, composite graft replacement in 10 patients, and coronary artery bypass grafting in 5 patients. RESULTS: The early mortality rate was 16% (11 of 70 patients). Multivariable analysis showed that renal-mesenteric ischemia and coronary artery bypass grafting were independent determinants for early death. Survival rates at 3 and 5 years postoperatively, including the early deaths, were 75% +/- 5% and 73% +/- 6%, respectively. Multivariable analysis showed that renal-mesenteric ischemia and en bloc repair were independent determinants for late death. Freedom from reoperation was 91% +/- 4% and 77% +/- 8% at 3 and 5 years, respectively. Multivariable analysis showed that anastomotic leakage was the only significant determinant for late reoperation. CONCLUSIONS: Extended total arch replacement for acute type A aortic dissection could be justified in properly selected patients.

Polymer sheet for covering tumors during endoscopic surgery.

It is recommended that tumor surface should be covered before resection in endoscopic surgery, but this is difficult to do, and no satisfactory method for this purpose has been reported. Therefore, we developed a polymer sheet to cover the wet surfaces of tumors. The sheet we developed is composed mainly of a cellulose derivative, ethyl citrate, and polyacrylic acid. Experimental and clinical study was performed to investigate the usefulness of the sheet. The sheet became attached to the organ surface by absorbing fluid secreted by tissues, and remained fixed for a period of 2 to 3 hours. No foreign body or allergic reaction was observed, and no postoperative infection occurred. The polymer sheet can be used safely for the purpose of covering tumors during endoscopic surgery.

Pharmacokinetic advantages of a newly developed tacrolimus oil-in-water-type emulsion via the enteral route.

We developed an oleic acid oil-in-water (o/w)-type emulsion of a new tacrolimus formulation that presented an improvement in the delivery of the drug for oral absorption. This investigation was undertaken to assess a sustained release drug delivery system and selective drug transfer into the lymphatic system. The whole blood concentration profiles after oral administration at a dose of 2 mg/kg and bone marrow, spleen, liver, lung, small intestine, kidney, brain, and whole blood distribution after oral administration at a dose of 1 mg/kg of o/w emulsion formulation of tacrolimus (O/W group) were compared with those of commercially available formulation (T group) in the rat. The mean diameter of the o/w emulsion droplets was 0.47 microm immediately after preparation. The tacrolimus entrapping efficiency of o/w emulsion was 71.3+/-5.0% in 12 h and did not change for 2 d. The area under the whole blood concentration-time curve (AUC) in the O/W group was significantly higher (P<0.01) than that in the T group. In contrast, the values of constant elimination rate and total clearance in the O/W group were significantly lower (P<0.01) than those in the T group, with a comparative bioavailability of 115.9%. The tissue concentration of tacrolimus in the O/W group was significantly higher levels in the bone marrow, spleen, liver, lung, and small intestine, and significantly lower in the brain and kidney, relative to the T group. The o/w emulsion of tacrolimus may be an improved dosage form via the enteral route.

Laparoscopic surgery for gonadal dysgenesis in children.

Three pediatric phenotypic females presented with gonadal dysgenesis. Their gonads were removed laparoscopically. These phenotypically normal females, who do not have any intersex problems or ambiguous genitalia, represent a unique group of patients having a Y chromosome or a fragment of it in their genetic constitutions. We performed laparoscopic adnexectomy with Endoloop ligatures or an ultrasonically activated scalpel. No significant complication occurred in any of the cases. Pathologic examination revealed gonadoblastoma in one of the gonads of one patient. We propose that laparoscopic surgery is a safe and minimally invasive procedure for prophylactic gonadectomy to prevent neoplasia, even when performed on pediatric patients.