Management of Blunt Thoracic Aortic Injuries: Endovascular Stents versus Open Repair

BACKGROUND

Endovascular stent graft (EV) technology has been successfully adapted to the repair of blunt traumatic aortic injuries. The purpose of this study was to compare the outcomes of patients treated with EV repair and open repair after blunt thoracic aortic trauma.

METHODS

A review of a tertiary trauma center's prospective trauma registry identified all patients who suffered a blunt traumatic thoracic aortic injury over an 11-year period (1991-2002). Operative interventions and outcomes were then compared.

RESULTS

Over an 11-year period, 18 patients underwent repair of a blunt thoracic aortic injury (EV, 6; open, 12). There were no significant differences in demographics, injury, or crash statistics between groups. The open group had a 17% early mortality rate (n = 2), a paraplegia rate of 16% (n = 2), and an 8.3% incidence of recurrent laryngeal nerve injury (n = 1). This is in contrast to a 0% rate of mortality, paraplegia, and recurrent laryngeal nerve injury in the EV group. A definite trend toward decreased morbidity, mortality, intensive care unit length of stay, and number of ventilator-dependent days was seen with EV repair.

CONCLUSION

We observed a clear trend toward improved outcomes after EV repair of thoracic aortic injuries compared with standard open repair. EV repair is emerging as the preferred method of repairing blunt thoracic aortic injuries in trauma patients with multiple injuries.

Gender Differences in Relative Dilatation of Abdominal Aortic Aneurysms

It has been postulated that gender differences in abdominal aortic aneurysm (AAA) rupture risk are due to variation in proportional dilatation. This study's purpose was to examine differences in relative dilatation of AAAs as related to rupture risk and repair thresholds. During a recent 20-month period (August 2003-March 2005), all patients receiving elective endovascular repair of an AAA underwent computer-generated computed tomographic measurements, including suprarenal aortic diameter (D1) and maximum aneurysm diameter (D3). As a measure of proportional dilatation, a D3/D1 ratio was calculated for each patient and compared between genders. Values for males and females were plotted separately (D3 vs. D3/D1), and the resulting linear regression equations allowed for the comparison of proportional dilatation of aneurysms between genders. In 129 patients (108 males, 21 females), mean D3 did not differ between genders (62 +/- 9.0 vs 63.4 +/- 10.8 mm, p = 0.89), while relative dilatation (D3/D1) was significantly greater in females compared to males (2.82 +/- 0.52 vs. 2.55 +/- 0.42, p = 0.02). Linear regression analysis allowed for comparison of D3 as a function of D3/D1 and correlated a 55 mm AAA in males with one of 52 mm in females. These differences became greater with increasing AAA diameters (e.g., 60 and 70 mm AAAs in a male were proportionally similar to 56 and 62 mm AAAs in a female). AAAs of equal diameter represent a greater proportional dilatation in females than in males. This supports the recommendation for a smaller aneurysm diameter (52 mm) threshold for repair in females rather than the commonly used 55 mm threshold in males. Also, these data suggest that the gender difference in rupture risk widens exponentially as aneurysm diameter, and thereby proportional dilatation, increases above this repair threshold.

Ruptured mycotic abdominal aortic aneurysm secondary to Mycobacterium bovis after intravesical treatment with bacillus Calmette-Guérin

Bacillus Calmette-Guérin (BCG) is a live attenuated strain of Mycobacterium bovis that has proven effective in the treatment of early-stage bladder cancer. Although intravesical therapy with BCG is generally considered safe, serious complications including hematuria, granulomatous pneumonitis, hepatitis, and life-threatening BCG sepsis are well known. BCG-related vascular infections are rarely reported. We present a case of a ruptured abdominal aortic aneurysm secondary to M bovis infection 2 years after intravesical instillation of BCG and review the related literature.

Objective scoring systems of medical risk: A clinical tool for selecting patients for open or endovascular abdominal aortic aneurysm repair

BACKGROUND

Objective scoring systems have been developed for risk stratification of open infrarenal aneurysm repair. To date, none have been applied for the selection of patients who would most benefit from either an open or an endovascular approach. This study assessed the utility of comorbidity-based objective scoring systems for defining subgroups of patients who might most benefit from open or endovascular aneurysm repair.

METHODS

A retrospective database review was performed for the period January 1999 to December 2004 to identify patients who had undergone elective open aneurysm repair (open repair) or elective endovascular aneurysm repair (EVAR). Validation of the Glasgow Aneurysm Score (GAS), the Modified Leiden Score (M-LS), and the Modified Comorbidity Severity Score (M-CSS) was performed for perioperative mortality risk in the open repair group. GAS, M-LS, and M-CSS were then calculated for the EVAR group. Differences in open repair vs EVAR mortalities were evaluated.

RESULTS

During the time period, 558 patients underwent open repair and 304 underwent EVAR. Overall mortality was 4.7% for open repair patients and 2.0% for EVAR. All three scoring systems were validated to our open repair data set (C statistic: GAS, 0.72; M-LS, 0.71; M-CSS, 0.74). A score was calculated for each system that separated patients into groups of either low or high risk of death for open repair. This score (cut point) was 76.5 for the GAS, 5.2 for the M-LS, and 8 for the M-CSS. Analysis of the EVAR population revealed that patients at low medical risk for open repair did not derive statistically significant mortality benefit with EVAR; however, patients at high medical risk for open repair derived significant benefit from EVAR (GAS>76.5 mortality: open repair, 7.8%; EVAR, 1.9% [P<.01]; M-LS mortality: open repair, 8.1%; EVAR, 2.5% [P<.01]; and M-CSS mortality: open repair, 10.3%; EVAR, 3.4% [P<.025]). Despite a very small number of deaths (n=6), receiver operator curve analysis identified M-LS and M-CSS as having some predictive ability for mortality risk with EVAR (C statistic: M-LS, 0.70; M-CSS, 0.69).

CONCLUSION

Three validated objective scoring systems can be used to categorize patients into two groups of medical risk: one that has excellent outcome with open repair and derives no early mortality benefit from EVAR, and another that has significant mortality with open repair and derives important benefit with EVAR.

Initiation of remote hepatic injury in the rat: interactions between Kupffer cells, tumor necrosis factor-alpha, and microvascular perfusion

Severe trauma may initiate a systemic inflammatory response, which in turn may result in remote organ injury. After limb ischemia/reperfusion (I/R), intravital fluorescence microscopy was applied to the livers of normotensive rats to investigate the initiation of remote injury to the liver. Additionally, we determined whether Kupffer cell activation and tumor necrosis factor-alpha (TNF-alpha) were involved, via perfusion deficits, in such injury. TNF-alpha, measured by immunoassay, peaked at 30 minutes of reperfusion, but returned to baseline within 60 minutes. Limb I/R resulted in significant increases to global hepatocellular injury measured by alanine transaminase (ALT) and lethal hepatocyte injury as seen with intravital fluorescence microscopy. Although the number of perfused sinusoids went unchanged, a significantly augmented perfusion heterogeneity was measured. After 1.5 hours of reperfusion, both TNF-alpha and Kupffer cells were shown to contribute to global hepatocellular injury (e.g., ALT). After 3 hours, TNF-alpha was no longer essential for this injury, suggesting that some other mechanism(s) activated Kupffer cells and initiated hepatocellular injury. Using propidium iodide and fluorescence microscopy, we found that both TNF-alpha and Kupffer cell activation were necessary to drive hepatocytes toward lethal injury. No additional benefits were observed with a combination of TNF-alpha inhibition and Kupffer cell suppression. These results not only implicate both Kupffer cells and TNF-alpha in the initiation of remote hepatic injury, but suggest that sinusoidal perfusion deficits are not essential for the initiation of such injury. Other mechanism(s) are likely involved in the pathogenesis of remote hepatic parenchymal injury.

Cytokines contribute to early hepatic parenchymal injury and microvascular dysfunction after bilateral hindlimb ischemia

PURPOSE

Hepatic dysfunction may contribute to death from multiple organ dysfunction after abdominal aortic surgery. Several factors are likely responsible, and the purpose of this study was to determine whether the cytokines tumor necrosis factor-alpha (TNF-alpha) and interleukin 1 (IL-1) are involved in initiating this remote hepatic injury.

METHODS

In a normotensive rat model of 4-hour bilateral hindlimb ischemia/reperfusion (I/R), we measured systemic TNF-alpha and IL-1 levels throughout the I/R period. Rats were randomly assigned to either the 3-hour control group, the 3-hour I/R group, or the I/R group with administration of a polyclonal antibody (PAb) to TNF-alpha (I/R + TNF-alpha PAb). Direct evidence of lethal hepatocyte injury through the labeling of nuclei by propidium iodide (per 10(-1)mm(3)) and altered microvascular perfusion were assessed by using intravital microscopy.

RESULTS

Systemic TNF-alpha peaked at 83.97 pg/mL (P <.05, n = 5) at 30 minutes of reperfusion and returned to baseline in 60 to 90 minutes. No significant change in systemic IL-1 was detected (P <.05, n = 4). Alanine aminotransferase increased 2.5-fold in the I/R group through 3 hours of reperfusion (P <.05, n = 4), and TNF-alpha PAb did not attenuate this alanine aminotransferase increase (P <.05, n = 6). Lethal hepatocyte injury increased by 8-fold in the I/R group compared with the control group (P <.05, n = 5), whereas TNF-alpha PAb significantly reduced this injury (P <.05, n = 4). No regional differences in injury were noted within the acinus. Total perfusion within the microvascular unit did not drop; however, significant flow heterogeneity was observed. The proportion of continuously perfused sinusoids declined in the I/R group after 3 hours of reperfusion in both periportal (62.0 +/- 2.2, P <.05) and, to a lesser, although significant, degree, in the pericentral regions (73. 2 +/- 1.73, P <.05).

CONCLUSION

By scavenging extracellular TNF-alpha with a PAb, we provide direct evidence that TNF-alpha contributes to, but is not solely responsible for, early remote hepatocellular injury and microvascular dysfunction. The administration of TNF-alpha PAb reduced lethal hepatocyte injury in both regions of the acinus and also improved perfusion in the periportal region (76.8 +/- 5.41, P <.05), but not in the pericentral region. This suggests that TNF-alpha released during reperfusion mediates early remote hepatocellular injury and microvascular dysfunction after a remote ischemic insult.

Successful replantation of nose by microsurgical technique, and review of literature

We present a case of total amputation of a major portion of the nose of a 10-year-old boy, which was successfully replanted by microsurgical technique. A 489-year review of the literature revealed the rarity of successful nasal replacement following amputation.

The reliability of differentiating neurogenic claudication from vascular claudication based on symptomatic presentation

BACKGROUND

Intermittent claudication can be neurogenic or vascular. Physicians use a profile based on symptom attributes to differentiate the 2 types of claudication, and this guides their investigations for diagnosis of the underlying pathology. We evaluated the validity of these symptom attributes in differentiating neurogenic from vascular claudication.

METHODS

Patients with a diagnosis of lumbar spinal stenosis (LSS) or peripheral vascular disease (PVD) who reported claudication answered 14 questions characterizing their symptoms. We determined the sensitivity, specificity and positive and negative likelihood ratios (PLR and NLR) for neurogenic and vascular claudication for each symptom attribute.

RESULTS

We studied 53 patients. The most sensitive symptom attribute to rule out LSS was the absence of "triggering of pain with standing alone" (sensitivity 0.97, NLR 0.050). Pain alleviators and symptom location data showed a weak clinical significance for LSS and PVD. Constellation of symptoms yielded the strongest associations: patients with a positive shopping cart sign whose symptoms were located above the knees, triggered with standing alone and relieved with sitting had a strong likelihood of neurogenic claudication (PLR 13). Patients with symptoms in the calf that were relieved with standing alone had a strong likelihood of vascular claudication (PLR 20.0).

CONCLUSION

The classic symptom attributes used to differentiate neurogenic from vascular claudication are at best weakly valid independently. However, certain constellation of symptoms are much more indicative of etiology. These results can guide general practitioners in their evaluation of and investigation for claudication.

Risk-adjusted analysis of early mortality after ruptured abdominal aortic aneurysm repair

PURPOSE

Ruptured abdominal aortic aneurysms (RAAAs) continue to result in early mortality in up to 50% of patients. Additionally, it remains difficult to compare outcomes given the variability in patient comorbidities and presentation. The purpose of this study was to describe an instrument that permits the prospective analysis of outcomes after RAAA repair while adjusting for the variability in preoperative risk.

METHODS

Consecutive patients undergoing attempted open RAAA repair over a 5-year period (1999 to 2003) at our center were reviewed. Thirty-day or in-hospital mortality was the main outcome variable. Preoperative mortality risk was estimated for each patient by using a validated modification of the POSSUM scoring system (V-POSSUM). A risk-adjusted cumulative sum method (RA-CUSUM) was used to compare observed versus predicted outcomes by assigning a risk-adjusted score, based on log-likelihood ratios, to each patient. These scores were sequentially plotted with preset control limits to allow for "signaling" when results were substantially different from expected (doubling or halving of odds ratios).

RESULTS

A total of 136 patients were reviewed, with an early mortality rate of 45.6%. V-POSSUM scores were accurate in predicting mortality for the entire cohort, with an observed-to-predicted mortality ratio of 0.92 (P = .80). Each patient's risk-adjusted score was plotted sequentially. In one segment of the resulting plot, the graph adopted a negative slope and crossed the lower control limit, indicating improved results compared with predicted.

CONCLUSIONS

V-POSSUM scores in this series accurately predicted early mortality after RAAA surgery. The RA-CUSUM method allows for the prospective evaluation of outcomes, while taking into account patient variability. In the current study, this resulted in the identification of a series of patients who had improved outcomes compared with predicted.

Split-thickness skin grafts and negative-pressure dressings in the treatment of axillary hidradenitis suppurativa

Although a number of different reconstructive techniques have been described for the treatment of axillary skin defects, split-thickness skin grafting continues to be the most common surgical modality. Here, we present our recent experience of using split-thickness skin grafts together with negative-pressure dressings for the management of defects following wide surgical excision of severe hidradenitis suppurativa. This technique ensures complete skin-graft take whilst allowing full shoulder mobility, thereby minimising the undesirable sequelae associated with split-thickness skin grafting alone.

A 3-year epidemiological review of burn unit admissions in Dublin, Ireland: 1988-91

A retrospective multifactorial epidemiological study of all patients admitted to the Burns Unit, St James's Hospital, Dublin during a 3-year period from January 1988 to December 1990 was undertaken. One hundred and twenty patients were admitted. All patients were aged over 14 years. The mean patient age was 48.2 years. Males accounted for 56 per cent of admissions. The mean percentage body surface area (%BSA) burned was 24.9 per cent. Flame was the cause of burns in 60 per cent of cases and produced the most extensive lesions. The home was the most common site of injury. Almost half the patients admitted from residential institutions sustained their burns in hot baths. Those aged over 60 years sustain smaller burns but are at increased risk from thermal injury. Twenty-one per cent of burns were caused by open fires used for heating the home. The mean time in hospital was 49.9 days. Twenty-three per cent of patients died as a result of their injuries. We have identified those living in residential institutions to be at increased risk from scald burns and suggest methods by which they may be protected.

Prevention of contrast-induced nephropathy in vascular surgery patients

Presently, only hydration and N-acetylcysteine have been shown to be effective in decreasing the incidence of radiographic contrast-induced nephropathy. We investigated the role of N-acetylcysteine and various hydration protocols in vascular surgery patients undergoing angiography. A single-center, randomized, placebo-controlled trial was conducted in patients with stable, preexisting renal dysfunction undergoing elective, outpatient angiography. Patients were randomized to outpatient oral hydration and N-acetylcysteine, inpatient hydration plus N-acetylcysteine, or our standard therapy of inpatient intravenous hydration alone. Two of twenty-eight (7%) patients who received outpatient oral hydration and N-acetylcysteine developed contrast-induced nephropathy, while two of 25 (8%) who recieved inpatient hydration plus N-acetylcysteine developed contrast-induced nephropathy and two of 25 (8%) who received standard therapy of inpatient intravenous hydration alone developed contrast-induced nephropathy. There was no statistical difference in incidence of contrast-induced nephropathy between the groups. No statistically significant independent risk factors were identified among the patients who developed contrast-induced nephropathy. N-Acetylcysteine did not confer additional benefit to patients treated with inpatient intravenous hydration. Outpatient oral hydration plus N-acetylcysteine was as effective at preventing contrast-induced nephropathy as inpatient therapies and avoided costly hospital admission.

Bupivacaine and Kaltostat reduces post-operative donor site pain

A prospective double blind controlled trial was carried out to examine the differences in post-operative split skin graft donor site pain between sites dressed with three differently treated types of dressing; a dry calcium alginate dressing (Kaltostat Britcair), a saline moistened Kaltostat dressing and a bupivacaine hydrochloride (0.5%) moistened Kaltostat dressing. There was a significant reduction in post-operative pain in the Kaltostat and bupivacaine group (group 3) at 24 and 48 h when compared to the other two groups (p < 0.04). There was no difference in ease of removal of dressings or the quality of wound healing on day 10 between the three groups. This study demonstrates a significant reduction in post-operative pain in bupivacaine soaked Kaltostat without reducing the beneficial effects of Kaltostat on donor site healing and we recommend its use in clinical practice.

Early Mortality Following Endovascular Versus Open Repair of Ruptured Abdominal Aortic Aneurysms

Purpose: To determine whether endovascular repair (EVAR) offers a survival advantage over open repair (OAR) with ruptured abdominal aortic aneurysms (RAAA). Methods: Retrospective analysis of RAAA patients treated between 2003 and 2008. Univariate and multivariate analyses were performed. Results: 167 patients presented with RAAA (OAR = 135, 80.8%, EVAR = 32, 19.2%). On univariate analysis, EVAR was associated with a decreased mortality relative to OAR, (15.6% vs 43.7%, P = .004). Patients who survived were younger (P < .0005), had a higher blood pressure (P < .0005), level of consciousness (P < .0005), and hemoglobin (P = .018), and a lower urea (P = .005) and international normalized ratio (INR; P = .001). On multivariate analysis, type of repair remained an independent predictor of 30-day mortality (OR: 0.121; 95% CI: 0.021-0.682, P = .017). Conclusion: Controlling for preoperative factors, EVAR is an independent predictor of lower 30 day mortality relative to open repair after RAAA. This supports the wider use of endovascular repair in all patients with RAAA.

Could your case of necrotising fascitis be Pyoderma gangrenosum?

Necrotising fascitis is a fulminant infective process which can result in significant morbidity and can indeed be life threatening. It needs to be recognised early and managed aggressively with extensive surgical debridement followed by appropriate antibiotics. On the other hand, Pyoderma gangrenosum is a disease process that needs to be managed non-surgically. We present one such case, the diagnosis of which had treaded along the thin line between the two.

The Association Between a Surgeon’s Learning Curve With Endovascular Aortic Aneurysm Repair and Previous Institutional Experience

The purpose of the present study was to determine whether an institution’s prior endovascular experience influenced the learning curve of subsequent surgeons. A prospective analysis of the initial 70 endovascular abdominal aortic aneurysm repair (EVAR) cases attempted by an individual surgeon was performed with the primary outcome variable being achievement and 30-day maintenance of initial clinical success. Along with standard statistical analyses, the cumulative sum failure method (CUSUM) was used to analyze the learning curve, with a predetermined acceptable failure rate of 10%. Seventy elective EVAR cases were performed by this surgeon during a 4-year period (2000-2004) (mean age, 73.7 ∓ 5.4 years; mean aneurysm diameter 63.3 ∓ 7.2 mm). Initial clinical success was achieved in 68 of 70 cases (97%), which differed significantly with that of our initial surgeon (88.5%, P = .01). Causes of failure in the present series included 1 early mortality (1.4%) and 1 case of conversion to open repair with no instances of type I endoleak or endograft limb thrombosis. Both surgeons’ cases were plotted sequentially with CUSUM curves revealing a significantly shorter learning curve for the second surgeon. Optimal results were achieved following 10 to 20 EVAR cases, as opposed to 60 cases in the initial series. Such an analysis confirms that as an institution’s experience with EVAR increases, an individual surgeon’s learning curve shortens considerably.

The Role of Platelet-Rich Plasma in Inguinal Wound Healing in Vascular Surgery Patients

The objective was to determine whether incision application of platelet-rich plasma (PRP) will decrease postoperative wound complications in vascular surgery patients. A prospective, randomized trial randomized 81 incisions in 51 patients who underwent femoral artery exposure for elective revascularization procedures or endovascular abdominal aneurysm repairs. Incidence of diabetes, chronic renal failure, prosthetic grafts, body mass index (BMI), and steroid use did not differ. Using the ASEPSIS wound classification system, we found no difference in incidence of wound infection. Wound complications occurred in 9 (23%) of 40 of PRP group and 9 (22%) of 41 of non-PRP. Severe wound complications developed in 5 (13%) PRP and 6 (5%) of non-PRP (P = NS). In multivariate analysis, there were no predictors for wound infection. Groin wound complications rates are common in this patient group. Platelet-rich plasma did not decrease the incidence of groin wound complications in our patients

Risk-Adjusted Analysis of Outcomes Following Elective Open Abdominal Aortic Aneurysm Repair

The purpose of this study was to describe a method to analyze outcomes following open abdominal aortic aneurysm (AAA) repair while considering the variability in patients' preoperative risk. Consecutive patients undergoing elective open infrarenal AAA repair during a 4-year period (2000-2003) were reviewed. Thirty-day or in-hospital mortality was the major outcome variable. Preoperative mortality risk was estimated for each patient using a validated scoring system that considers age, renal dysfunction, and coronary artery and cerebrovascular disease. A risk-adjusted cumulative sum method was used to compare observed versus predicted outcomes by assigning a risk-adjusted score, based on log-likelihood ratios, to each patient. These cumulative scores were sequentially plotted with preset control limits to allow for "signaling" when results were substantially different than expected (doubling or halving of odds ratios). Four hundred and sixty-three patients were studied with an overall early mortality rate of 4.5% (n = 21). Patients were allocated to three different preoperative risk groups (low, n = 89; medium, n = 160; high, n = 214) according to a medical comorbidity-based scoring system. Predicted (P) and observed (O) mortality rates for each group were as follows: low, 2.4% (P) and 2.2% (O); medium, 4.1% (P) and 4.4% (O); high, 9.3% (P) and 5.6% (O). The resulting risk-adjusted scores for each patient were plotted sequentially. This plot was flat for the first year and then adopted a negative slope crossing the lower control limit after 266 patients, indicating improved results compared to those expected. This coincided with the adoption of routine intraoperative cell saver use in our practice. This form of analysis allows for the prospective evaluation of results while considering patient-mix variabilities.

Fibrinogen survival and fibrinolysis in acute leukemia

Fibrinogen survival using 125I-labelled homologous fibrinogen was studied in 17 adults with acute leukemia. Five patients in complete remission had normal fibrinogen survival and turnover rate. Five of 6 patients undergoing induction therapy and 4 of 6 in relapse had shortened fibrinogen survival; the turnover rate was increased in all 12 patients. Nine of 12 patients with active disease had elevated levels of fibrinogen degradation products in the serum. Serial coagulation studies did not support the diagnosis of overt disseminated intravascular coagulation. There was no correlation between the morphological type of leukemia, chemotherapy, the presence of fever and sepsis, or liver dysfunction and fibrinogen survival. Other possible causes of the accelerated fibrinogen turnover in patients with active disease are discussed.

Endovascular Repair of Thoracic Aortic Disease: Early and Midterm Experience

Thoracic aorta disease remains a challenging problem, and despite improvements, open repair techniques are still associated with significant morbidity and mortality. This is a retrospective review of 53 consecutive patients with thoracic aortic pathology who were treated with endovascular repair between September 1998 and December 2004 at a tertiary-care hospital. Endovascular stent graft placement was performed on 23 elective and 30 emergent patients (34 male patients, mean age 66 years, 21 to 85 years). Completion angiography revealed no endoleak in 47 (89%) patients, a type I endoleak in 4 patients, and a type II endoleak in 2 patients. Operative 30-day mortality for elective aneurysms (n = 22), emergent aneurysms (n = 10), dissection (n = 3), penetrating aortic ulcers (n = 7), and trauma (n = 11) was 0%, 40%, 0%, 29%, and 9%, respectively. In total, 46 (87%) patients survived 30 days, and 36 (78.3%) of the survivors were discharged home free of complications. Two patients (4%) experienced paraplegia. Median follow-up was 22 months (1 to 72 months). Intermediate-term results revealed 41 (89%) patients free of endoleak, stent migration, or aneurysmal expansion. Two (4%) patients required reintervention with an additional stent graft. There were 2 (4%) patients with late aortic-related deaths and four (9%) patients with non—aorticrelated late deaths. Endovascular stent graft placement for thoracic aorta disease can be performed successfully and safely with good perioperative and intermediate-term outcomes. Stent graft complication and reintervention rates are low, whereas intermediate survival rates are good. Long-term efficacy still needs to be evaluated.

Comparison of renal function after endovascular aneurysm repair with different transrenally fixated endografts

OBJECTIVE

Transrenal fixation of abdominal aortic endografts may provide a more secure proximal attachment with few deleterious effects with respect to renal function. This study's purpose was to determine whether different metals used in two commercially available endografts (Cook Zenith and Medtronic Talent) result in different effects on renal function when placed across renal ostia.

METHODS

A total of 140 consecutive patients, between August 2003 and April 2005, who underwent elective endovascular repair of an aortic aneurysm with a nitinol or stainless steel-based endograft with transrenal fixation were reviewed with a mean follow-up period of 5.5 months (range, 1-22 months). The main outcome variable was the percentage change in creatinine clearance (CrCl), which was determined before surgery and at the most recent follow-up. Multiple regression analysis was performed to analyze the contribution of various factors to any deterioration in renal function.

RESULTS

The 140 patients were predominantly male (86%), with a mean age of 75 years (range, 56-92) and a mean aneurysm diameter of 62 mm (range, 42-110 mm). The mean intraoperative contrast use was 67 mL (range, 45-160 mL), and after surgery these patients received a mean of 3 surveillance computed tomographic scans (range, 1-7). Nineteen cases (13.6%) required deliberate accessory renal artery coverage. CrCl did not change significantly after surgery; the mean change in CrCl at the end of follow-up was a 2.5% decrease. There was no difference in the reduction in CrCl between endograft types. Only 14.3% of patients experienced a greater than 20% decrease in CrCl. Multiple regression analysis failed to show a relationship between change in renal function and age, sex, aneurysm diameter, infrarenal neck dimensions, endograft type, coverage of accessory renal arteries, intraoperative contrast volume, preoperative CrCl, and postoperative computed tomographic scans. Length of follow-up was an independent predictor (P = .04).

CONCLUSIONS

Transrenal endograft fixation results in little deterioration in renal function during intermediate follow-up. The few patients who do experience a decline in renal function do so independently of any features related to the initial endovascular repair, and there is no difference in renal deterioration between endografts with nitinol and stainless steel transrenal bare metal stents.

Characterization of baboon class I major histocompatibility molecules. Implications for baboon-to-human xenotransplantation

Increasingly strong medical and political pressures are stimulating consideration of the transplantation of baboon organs and cells into humans. Critical to the success of these xenotransplants is management of the immune system such that graft rejection and, in the case of bone marrow transplantation, graft-versus-host disease do not result in transplant failure. The polymorphic products of the major histocompatibility complex (MHC) are the primary barrier to successful allotransplantation, and here we describe class I MHC molecules from baboon (Papio anubis) to gain an understanding of how similarities and differences between baboon and human MHC molecules might affect xenograft survival and function. Comparative analyses of our five novel baboon class I molecules with defined HLA class I molecules demonstrate that the baboon class I molecule are up to 90% identical. Disparity between baboon class I proteins and their human homologues lies predominately at positions in the antigen-binding groove, while C-terminal portions of the class I heavy chain are more conserved between the two species. Such concentration of cross-species differences within the alpha1 and alpha2 domains involves a majority of substitutions at positions demonstrating polymorphism in human alleles; the location of substitutions distinguishing baboon and human molecules thus resembles the positioning of human class I allopolymorphisms. Because this preliminary characterization indicates that both baboon and human T cells with be restricted by xenogeneic class I molecules, immune responses triggered during baboon-to-human transplantation should mimic those arising during MHC mismatched human allotransplantation.