Neoral conversion from Sandimmune in maintenance renal transplant patients: an individualized approach

When converting maintenance renal allograft recipients from Sandimmune (cyclosporin A [CsA]) to Neoral (CsA-microemulsion [CsA-ME]), a dose conversion ratio of 1:1 may not be optimal, in part because of the variability in absorption of the CsA formulation of cyclosporine. After conversion using a 1:1 dose ratio, an individualized approach to the management of dosing was applied. In this article, close monitoring, which began at the time of conversion, and rapid response to potentially meaningful changes in cyclosporine trough levels early in the postconversion course were used to maintain patients' cyclosporine troughs at preconversion levels. The results of cyclosporine dose changes after converting stable, maintenance renal transplant patients from CsA (once daily and twice daily) to CsA-ME (twice daily) during 52 wk of follow-up are reported. Most patients (87.2%) required CsA-ME dose reduction to maintain preconversion trough levels, and 64% of the patients attained their CsA-ME maintenance dose by study week 4. Logistic regression analysis identified one significant predictor concerning the week 52 CsA-ME dose: patients converted from CsA doses > or = 4.0 mg/kg per d were more likely to require dose reduction (P < 0.0001). Although firm guidelines for dose modification after conversion from CsA to CsA-ME cannot be provided because of the individual nature of cyclosporine absorption, an individualized approach to patient management is recommended. Patients with higher CsA doses before conversion are particularly likely to require dose reduction early in the postconversion course. With CsA-ME, good absorbers of cyclosporine remain good absorbers, or become better absorbers, whereas poor absorbers become good absorbers.

Losartan, an angiotensin II type 1 receptor antagonist, lowers hematocrit in posttransplant erythrocytosis

The mechanism by which angiotensin-converting enzyme inhibitors reduce red cell mass in renal transplant recipients with erythrocytosis is unclear. To examine the role of angiotensin II in this disorder, losartan (a competitive antagonist of the angiotensin II type 1 [AT1] receptor) was administered to 23 patients with erythrocytosis. Fourteen patients took 25 mg/d for 8 wk; nine others were treated with 50 mg/d for 8 wk. Hematocrit decreased from 0.527 +/- 0.027 to 0.487 +/- 0.045 after 8 wk (P < 0.01)--by at least 0.04 in 19 patients. Decrement in hematocrit in the initial 8 wk of therapy was significantly greater in patients administered 50 mg/d than in patients on 25 mg/d. Twelve of 14 patients initially treated with 25 mg/d showed a small change in hematocrit; the dose was increased to 50 mg/d for 8 more wk. Hematocrit decreased from 0.528 +/- 0.030 before losartan treatment to 0.483 +/- 0.055 after 16 wk (P < 0.01). After therapy, serum erythropoietin significantly decreased in eight patients with elevated baseline levels, but not in 15 patients with normal baseline levels; however, hematocrit significantly decreased in both groups. Losartan was withdrawn in 16 patients; hematocrit increased from 0.440 +/- 0.057 to 0.495 +/- 0.049 after 8.9 +/- 7.5 wk (P < 0.001), without change in serum erythropoietin. Thus, specific blockade of AT1 receptors inhibited erythropoiesis, suggesting a pathogenic role for angiotensin II in posttransplant erythrocytosis.

Effects of magnesium sulfate on electrical ventricular defibrillation of dogs

Magnesium ion infusion has been reported for treatment of hypomagnesemia often associated with myocardial infarction and with surgeries involving cardiopulmonary bypass (CPB). Magnesium infusion before CPB has been reported to adversely affect the ability to defibrillate after CPB. However, there are also reports of magnesium ion infusion facilitating defibrillation of refractory ventricular fibrillation. This study evaluated the isolated effect of magnesium ion infusion on the shock intensity requirements for electrical defibrillation. The electric current required to defibrillate with 50% success (the ED50) was estimated in five mongrel dogs at baseline and again after each of four magnesium sulfate (80 mg/kg) infusions. The total serum magnesium level increased from 2.32 +/- 0.08 mg/dL (mean +/- SD) to 7.92 +/- 0.80 mg/dL. The mean estimated ED50 decreased from 12.8 +/- 2.9 A at baseline, to 11.1 +/- 0.8 A after the fourth infusion (P < .05), decreasing the delivered energy by 25%. Magnesium sulfate infusion was associated with a significant decrease in the electrical requirements for defibrillation. Key words: magnesium, electrical ventricular defibrillation.

Treatment of hypertension in renal allograft patients: does drug selection make a difference?

Recent trials have suggested that control of mild to moderate hypertension can slow progression of many forms of chronic renal disease. These findings may apply to renal transplant hypertension. Renal transplant hypertension, however, does not always behave like other forms of hypertension. Thus, clinical trials have not yet shown that blood pressure control will alter the progression of "chronic rejection." What's more, which of the classes of antihypertensive agents might be most effective is also not certain. Most trials suggest that calcium inhibitors and angiotensin-converting enzyme inhibitors have similar effects on blood pressure and glomerular filtration rate in hypertensive transplant patients.

In vivo left ventricular assist induced coagulation derangements. Comparison of Sarns-3M and St. Jude Medical circuits

An in vitro comparison of centrifugal pumping systems manufactured by Sarns-3M and St. Jude Medical revealed a difference in blood cell derangement. The purpose of this study was to compare in vivo the effects of 96 hr of left ventricular assist (LVA) on indexes of coagulopathy, hemolysis, and complement activation. Two groups of calves (each: n = 5) were instrumented with identical left atrial to thoracic aorta centrifugal pumping circuits using either Sarns-3M or St. Jude centrifugal pumps. Laboratory evaluations were performed pre-assist and at 1, 4, 24, 48, 72, and 96 hr during LVA. Platelet counts dropped significantly by 24 hr (Sarns-3M: 28%; St. Jude: 30%); no significant change in function was noted. Activated clotting time increased slightly (p > 0.05). Prothrombin time increased at 4 and 24 hr of LVA, returning to baseline by 96 hr (p < 0.05). Activated partial thromboplastin time increased with the St. Jude device from 24 to 96 hr on LVA (p < 0.05); the increase with the Sarns-3M device never reached significance. No significant changes in lactate dehydrogenase or plasma free hemoglobin were detected. Complement fraction C5a rose by 1 hr of LVA (p < 0.05), peaking at 4 hr and returning to baseline by 96 hr with both pumps. No significant difference was detected between pump groups for any of the parameters. It was concluded that 1) 96 hr Sarns-3M and St. Jude LVA caused coagulation derangement in calves, 2) neither pump demonstrated an advantage regarding coagulation and complement parameters, 3) hemolysis observed with the Sarns-3M pump in vitro was not evidenced in vivo, and 4) in vitro evidenced centrifugal pump differences may not be realized in vivo.

Feasibility of mathematical models to predict success in video-assisted thoracic surgery lung nodule excision

BACKGROUND

Pulmonary nodules are occasionally difficult to excise using video-assisted thoracic surgery (VATS).

METHODS

To predict operative success, mathematical models using preoperative computerized tomography (CT) measurements were tested in 50 consecutive patients who underwent attempted or successful thoracoscopic lung biopsy. Unrelated technical problems resulted in the exclusion of 3 patients.

RESULTS

No differences were noted with respect to lobar location, thoracic dimensions, gender, presence of chronic obstructive pulmonary disease, or nodule pathology. The expression S/(D + 1), where S = nodule size (cm) and D = distance (cm) to the nearest visceral pleura, yielded significantly higher values for visible nodules (P < 0.001). Resectable nodules had a higher score using the expression 1/(S + D + 1), (P < 0.001). Simple cases (n = 19) were defined as those in which nodules were both visible and resectable with very basic VATS techniques. All others (n = 28) were considered complex. The derived expression for Simplicity [1/(S(D + 1))] yielded significantly higher values for simple cases (0.8 +/- 0.3 vs. 0.3 +/- 0.2 cm(-2), P < 0.001) and all simple cases had a score > or = 0.4. Logistic regression analysis showed that the formulas for resectability and simplicity were significant independent predictors for resectability and simplicity.

CONCLUSIONS

Equations based on objective CT measurements may be useful for planning VATS nodulectomy or studying the outcome of these minimally invasive operations.

The impact of renal transplantation on survival in hepatitis C-positive end-stage renal disease patients

Hepatitis C virus (HCV) infection is common in end-stage renal failure patients. It is not known whether the prognosis of HCV-positive patients differs depending on whether they remain on dialysis or receive a kidney transplant. To address this question, we compared the outcomes of HCV-positive renal transplant recipients and HCV-positive patients who were acceptable candidates but had not yet received transplants. We reviewed all patients referred to our institution for renal transplantation evaluation between January 1992 and December 1995. Anti-HCV antibody was detected in 151 of 2,053 (7.4%) patients. HCV-positive patients were more often male (74% v 56%; P < 0.0001), black (68% v 49%; P = 0.001), unemployed (87% v 74%; P = 0.0004), on dialysis (88% v 78%; P = 0.0026), and on dialysis longer (30 +/- 44 months v 13 +/- 23 months; P = 0.0001) than HCV-negative patients. We determined the outcomes of HCV-positive patients who had at least 2 years' follow-up. Thirty-three HCV-positive patients received kidney transplants (group I); 25 HCV-positive patients were acceptable transplant candidates but had not yet received an allograft (group II). Group I and II HCV-positive patients were similar with respect to age, race, duration of dialysis, cause of renal failure, prevalence of heart disease, and results of liver function tests. Survival was significantly decreased in group II versus group I (P = 0.043). Our study showed that HCV-positive renal transplant recipients had a better survival than similar HCV-positive patients awaiting transplantation.

Organ preservation solutions in heart transplantation--patterns of usage and related survival

Despite experimental advantages for certain heart preservation solutions (HPS), their clinical popularity and related survival are uncertain. We surveyed all active UNOS heart transplant centers to determine their HPS. HPS survival benefits were tested using the UNOS heart transplant registry. Centers used from 1 to 3 types of 167 solutions. Of these formulations, 55.1% were commonly cited solutions. The other (custom) mixtures differed from those usually reported. All solutions were classified as intracellular (I, [Na++] < 70 mEq/L) or extracellular (E, [Na++] > or = 70 mEq/L). Significant variations in solution usage were observed among major regions of U.S. transplant activity (Northeast [NE], Southeast [SE], and West [W], P < 0.001). For example, 62.5% of University of Wisconsin (UW) and 49.3% of "Other" usage occurred in the NE; 75% of Roe and 100% of Collins usage occurred in the SE; and 100% of Krebs and 46% of Stanford usage occurred in the W. Logistic regression analyses of 9401 patients who underwent transplantation from 10/87 to 12/92 showed a reduction in the adjusted one month mortality odds ratio for grafts preserved with I rather than E solutions (0.85, P < 0.05). Compared with the most commonly used solution, Plegisol (20.1% of cases), the following adjusted odds ratios for one-month mortality were observed: UW, 1.09 (ns); Stanford, 0.80 (P < 0.10); Roe, 0.36 (P < 0.001); Collins, 0.82 (ns); Krebs, 0.14 (P < 0.01). Using the same one month comparison with Plegisol, 16.8% of grafts that received Custom-I solutions also fared better (0.75, P < 0.05) than the 21.4% that had Custom-E mixtures (0.91, ns). HPS usage varies greatly and there are regional preferences. There may be early survival benefits for certain intracellular HPS--however, further study is warranted to explore such relationships.

Differential gene expression of extracellular matrix components in dilated cardiomyopathy

Extracellular matrix metalloproteinases (MMPs) are activated in dilated cardiomyopathic (DCM) hearts [Tyagi et al. (1996): Mol Cell Biochem 155:13-21]. To examine whether the MMP activation is occurring at the gene expression level, we performed differential display mRNA analysis on tissue from six dilated cardiomyopathy (DCM) explanted and five normal human hearts. Specifically, we identified three genes to be induced and several other genes to be repressed following DCM. Southern blot analysis of isolated cDNA using a collagenase cDNA probe indicated that one of the genes induced during DCM was interstitial collagenase (MMP-1). Northern blot analysis using MMP-1 cDNA probe indicated that MMP-1 was induced three- to fourfold in the DCM heart as compared to normal tissue. To analyze posttranslational expression of MMP and tissue inhibitor of matrix metalloproteinase (TIMP) we performed immunoblot, immunoassay, and substrate zymographic assays. TIMP-1 and MMP-1 levels were 37 +/- 8 ng/mg and 9 +/- 2 ng/mg in normal tissue specimens (P < 0.01) and 2 +/- 1 ng/mg and 45 +/- 11 ng/mg in DCM tissue (P < 0.01), respectively. Zymographic analysis demonstrated lytic bands at 66 kDa and 54 kDa in DCM tissue as compared to one band at 66 kDa in normal tissue. Incubation of zymographic gel with metal chelator (phenanthroline) abolished both bands suggesting activation of neutral MMP in DCM heart tissue. TIMP-1 was repressed approximately twentyfold in DCM hearts when compared with normal heart tissue. In situ immunolabeling of MMP-1 indicated phenotypic differences in the fibroblast cells isolated from the DCM heart as compared to normal heart. These results suggest disruption in the balance of myopathic-fibroblast cell ECM-proteinase and antiproteinase in ECM remodeling which is followed by dilated cardiomyopathy.

Benefits of continued cyclosporine through an indigent drug program

Financial circumstances force some stable renal transplant recipients to discontinue cyclosporine (CsA). Previous results from our center document a subgroup of these patients at increased risk for acute rejection and allograft loss, namely, those of African ancestry. After 1988, such disadvantaged recipients have been able to receive CsA at no charge through the National Organization for Rare Disorders (NORD). At the University of Alabama at Birmingham, 54 patients were enrolled in the NORD program between 1988 and 1994. Acute rejection, allograft survival, and patient survival in these patients were compared with those in 42 patients who, prior to 1988, were withdrawn from CsA for financial reasons. Both groups were similar socioeconomically. The mean follow-up was 69 +/- 33 months (+/-SD) in the withdrawal group and 45 +/- 14 months in those entering the NORD program. Acute rejections occurred with similar frequency in both groups before CsA withdrawal (45%) or NORD enrollment (48%). In contrast, acute rejections were more common in patients after the onset of CsA withdrawal (38%) than after NORD enrollment (11%) (P < 0.01). Black patients withdrawn from CsA experienced more acute rejections than their counterparts in the NORD program (57% v 15%) (P < 0.01). White NORD recipients also experienced fewer acute rejections, although the difference was not statistically significant (withdrawal group 16% v NORD group 4%; P = 0.29). Rejection episodes were accompanied by reduced graft survival in black patients withdrawn from CsA, while significant improvement was seen in those remaining on CsA-based therapy (P < 0.05). No difference in allograft survival was seen among white patients in either group (withdrawal group 74% v NORD group 82%; P = 0.33). Thus, long-term access to CsA through the NORD program reduced acute rejections and improved allograft survival in an economically disadvantaged subgroup of renal transplant recipients. These findings emphasize the importance of continued access to CsA in black renal transplant recipients and its influence on long-term allograft survival.

Post-transcriptional regulation of extracellular matrix metalloproteinase in human heart end-stage failure secondary to ischemic cardiomyopathy

Human heart matrix metalloproteinases (MMP) are present in the latent form and activated in the failing heart. To examine whether the MMP activation was due to gene and/or post-translational modification, we analysed tissue from 10 explanted hearts due to coronary heart disease (CHD) and five normal left atrial tissue from donor hearts. Based on in situ immunolabeling MMP-1, tissue inhibitor of metalloproteinase (TIMP-1) and collagen were co-localized in the interstitial tissue. Based on sandwich ELISA, TIMP-1 and MMP-1 levels were 37 +/- 8 ng/mg and 9 +/- 2 ng/mg in normal tissue (P < 0.01) and 12 +/- 5 ng/mg and 75 +/- 11 ng/mg in the infarcted tissue (P < 0.01), respectively. These levels suggest repression of TIMP-1 during myocardial infarction. Northern blot analysis indicated that the mRNAs for both MMP-1 and TIMP-1 were increased three-to four-fold in the infarcted tissue as compared to the normal tissue, suggesting upregulation of MMP and TIMP gene transcription following infarction. Based on in situ tissue overlay zymography, the generalized activation of MMP was observed in the interstitium of the infarcted heart. Zymographic and immunoblot analysis demonstrated the presence of one band at 66 kDa (MMP-2) in the normal tissue and several bands at 92 (MMP-9), 66 (MMP-2) and 54 kDa (MMP-1) in the infarcted heart. Incubation of the zymographic gel with metal chelator (phenanthroline) abolished bands at 92 kDa and 54 kDa but phenanthroline did not abolish the lytic band at 66 kDa. The 66 kDa band was completely abolished in the presence of phenanthroline and phenyl methyl sulfonyl fluoride (PMSF). 2D-zymographic analysis suggested that the lytic band at 66 kDa was a mixture of two neutral proteinases with different isoelectric point. Plasminogen/gelatin zymographic analysis of infarcted tissue extract indicated that the band at 66 kDa was plasmin generated due to increased expression of tissue plasminogen activator (tPA) activity. In relation to increased expression of gelatinase in the infarcted tissue, our data suggest that gelatinase B (92 kDa) is induced in diseased heart. The results suggest that tPA converts plasminogen to plasmin which, in turn, activates MMPs and inactivates TIMP-1 post-translationally following ischemic cardiomyopathy.

Amlodipine increases cyclosporine levels in hypertensive renal transplant patients: results of a prospective study

Calcium channel blockers (CCB) are considered the agents of choice to treat hypertension in cyclosporine (CsA)-treated renal transplant patients. Verapamil, diltiazem, and nicardipine, but not nifedipine or isradipine, can significantly increase CsA levels. The effect of a new CCB, amlodipine, has not been established. However, some hospitals are routinely switching patients to amlodipine from other CCB for reasons of cost. A case of a man with stable CsA levels who developed significantly increased CsA levels after being changed to amlodipine is presented along with a prospective trial to formally examine this issue. Eleven hypertensive, CsA-treated renal transplant patients were placed on amlodipine for an average of 6.9 wk and later withdrawn. Three measurements of CsA trough level, blood pressure, serum creatinine concentration, and BUN were obtained at baseline, during treatment with amlodipine, and after withdrawal of amlodipine. CsA levels on amlodipine increased an average of 40% above baseline (P = 0.003) and decreased to baseline (P = 0.001) after amlodipine was withdrawn, despite no significant change in CsA dose. Additionally, there was no change in serum creatinine, BUN, or mean arterial pressure values. Amlodipine can increase CsA levels

A calf model for left ventricular centrifugal mechanical assist

The increased use of centrifugal mechanical assist (CMA) for treatment of refractory postcardiotomy cardiogenic shock highlights the need for experimental testing to improve clinical results. This report describes the preoperative conditioning, anesthetic and surgical technique, and postoperative management of a reliable calf model refined in this laboratory for in vivo subchronic (96 h) testing of CMA. Holstein bull calves (2 to 3 months old; mean body weight, 78 kg; n = 35) were instrumented for left ventricular CMA; 4 of these calves were sham-operated controls. Anesthetic recovery and postoperative restraint were accomplished in a specially designed crate to which each calf was preconditioned extensively. Younger calves were more readily conditioned and more tolerant of postoperative restraint than older calves. One calf died of ventricular fibrillation intraoperatively. One calf that had been heparinized developed uncontrollable hemothorax and died 12 h postoperatively. One calf prematurely dislodged his aortic cannula 15 h postoperatively and exsanguinated. Six calves developed pelvic limb paresis or paralysis because of lumbar spinal cord thromboembolism by 36 h postoperatively, and 3 of these calves were sacrificed by 42 h postoperatively. Fifteen calves required sedation in the first 12 h after the operation. Tachycardia associated with bottle feeding occurred in 15 calves. Second-degree atrioventricular block was noted frequently during deep relaxation. Postmortem examination demonstrated the absence of surgical wound and distant infection, security of cannulae in all but the calf that prematurely dislodged the aortic cannula, absence of thrombus formation at cannulation sites, and presence of thromboembolism in 51% of the calves. The incidence of thromboembolic lesions was not influenced by the need for chemical restraint, by the occurrence of feeding-associated tachycardia, or by the presence of atrioventricular block. There were no thromboembolic lesions in any of the sham-operated controls.

Should pulmonary lesions be resected at the time of open heart surgery?

The prevalence and malignant potential of pulmonary lesions found preoperatively in patients undergoing coronary artery bypass grafting (CABG) surgery are poorly defined. In a review of 3364 consecutive patients undergoing CABG, 191 (5%) were found to have pulmonary lesions. Granulomatous disease was suspected in all patients who had only calcified lesions (n = 151). These were empirically observed with no changes seen at follow-up. The 40 patients with noncalcified lesions (NCLs) were managed variously. Twenty patients underwent resection of the suspicious pulmonary lesion at the time of cardiac surgery. One patient underwent wedge resection of a pulmonary lesion (benign granuloma) 4 days before CABG. Eighteen patients underwent concomitant pulmonary resection and CABG through the median sternotomy (7 benign, 11 malignant). A delayed pneumonectomy was performed 17 days after CABG in another patient. Three of 40 patients died during the perioperative period without pathologic diagnosis. The remaining 17 were followed with serial roentgenograms. Three of 17 (18%) had lesional enlargement in the follow-up period their lesions were found to be malignant. The remaining 14 patients have been observed without surgical intervention now with a mean follow-up of 5.7 years (range, 20 months to 13 years). The prevalence of malignancy in lesions found on CABG preoperative chest roentgenograms was 15 out of 191 (7.8%); however, among patients with NCL the prevalence of malignancy was 15 out of 40 (37%), and malignancy was present in 12/13 (92%) of patients with NCLs that were >/= 2 cm in diameter. When malignancy is diagnosed in an NCL before CABG surgery, the decision to proceed with CABG should be based upon the coronary pathophysiology and the stage and cell type of the malignancy. Concomitant CABG and pulmonary resection is possible in most cases; however, we prefer a staged resection of all newly diagnosed NCLs when these are identified in patients requiring emergent revascularization or when these lesions are difficult to access through sternotomy. The mortality rate may be slightly increased in patients having concomitant procedures (5.47%) versus isolated CABG (3%). The incidence of malignancy in these NCLs is related to size. If a staged resection is not undertaken after CABG, careful observation of NCLs is important, as 18 per cent of these so managed were ultimately found to be malignant.

Possible mediators in hypertension: renal factors

Hypertension is more prevalent and more severe in African Americans compared with whites. Evidence is presented that support an important role of the kidney in the excess incidence of hypertension in this population group. There are quantitative differences in renal physiology between hypertensive African Americans and whites, the most dominant of which is an increased renal vascular resistance in African Americans that might be structural or functional. This increased renal vascular resistance might represent an underlying primary renal disease that has remained concealed among the spectrum of diseases referred to as benign nephrosclerosis. The answer(s) to this intriguing question will provide a better understanding of the kidney as a mediator and/or target of hypertension.

Dilemmas in renal transplantation: when the clinical course and histological findings differ

Histological examination of renal allograft tissue has become the accepted standard in diagnosing acute rejection. We present three cases of allograft dysfunction in which the histological findings and clinical course differed. Reliance on histology alone in therapeutic decision making might have resulted in inappropriate clinical interventions. In renal transplantation, biopsy results must always be interpreted in conjunction with clinical findings.

Impact of donor/recipient size matching on outcomes in renal transplantation

Interest in nonimmunologic factors affecting longterm graft survival has focused on adequacy of nephron dosing. Body surface are (BSA) is a reliable surrogate for nephron mass. In a retrospective study of 378 primary recipients of paired kidneys from 189 cadaveric donors, we assessed the impact of matching donor and recipient BSA on outcome over 7 years. BSA of donors was 1.82 +/- 0.26 m2. Initially, paired recipients of kidneys from a single donor were divided into two groups. Group 1 included the recipient with the larger BSA of the pair (1.97 +/- 0.17 m2), while group 2 consisted of smaller BSA recipients (1.69 +/- 0.19 m2). Although early function was better in group 2 patients, graft survival at 1 year (77% vs. 79%) and 5 years (54% vs. 55%) was identical between groups, as were most recent serum creatinine levels (2.0 +/- 0.1 vs. 2.1 +/- 0.1 mg/dl). A second analysis divided patients with a functioning allograft at discharge from initial transplant hospitalization (n = 345) into three groups based solely on donor to recipient BSA ratio: the ratio of group A (n = 30) was < or = 0.8, that of group B (n = 255) was between 0.81 and 1.19, and that of group C (n = 51) was > or = 1.2. Graft survival and kidney function over 5 years did not differ among groups. In multivariate analysis of 17 variables, donor:recipient BSA, independent of other risk factors, did not affect risk allograft loss. These data indicate that including nephron mass as a criterion for cadaveric organ allocation is unlikely to improve long-term results in renal transplantation.

Improved method for deep thoracoscopic lung nodule excision

Minimally invasive excision of deep lung nodules can be difficult partly because endoscopic staplers do not open wide enough. We describe a method in which a standard atraumatic straight clamp compresses the lung to allow placement of the stapler without difficulty.

Cyclosporine bioavailability: dosing implications and impact on clinical outcomes in select transplantation subpopulations

Reports in the literature indicate that clinical outcomes in select patient subpopulations have been inferior to those in the general transplantation population. Of potential interest in this regard is the finding that lower cyclosporine bioavailability correlates with a higher incidence of acute rejection and graft loss. To gain insights into these issues, we examined data from renal transplant recipients at our own centers and in one large data base. Our experience revealed that cyclosporine bioavailability was markedly lower in patients who developed acute or chronic rejection than in those with stable graft function. An analysis by demographic or clinical factors showed that cyclosporine bioavailability was lower in diabetics and black patients. In one study, diabetics required much higher daily doses of cyclosporine to achieve outcomes comparable to those in non-diabetics; even then, diabetics attained lower cyclosporine blood levels. Other work found that long-term graft survival rates were poorer in blacks, even though cyclosporine dosages and blood levels were comparable to those in whites. A case-controlled study from the pregnancy registry found that cyclosporine dosages were consistently higher in pregnant patients who maintained good graft function than in those who experienced graft dysfunction. These results suggest that the subpopulations examined should receive immunosuppression with higher cyclosporine dosages than those used in the general transplantation population. These subpopulations may also benefit from a cyclosporine formulation that provides better absorption, resulting in more consistent and predictable cyclosporine bioavailability.

Use of centrifugal pumps for postcardiotomy ventricular failure: technique and anticoagulation

BACKGROUND

Centrifugal pumps have been employed most commonly for postcardiotomy mechanical support after intraaortic balloon pumping has failed. Despite their effectiveness in some patients, morbidity remains high.

METHODS

Our clinical experiences with centrifugal pumps were reviewed with particular attention to common morbidity such as bleeding, coagulopathy, and thromboembolism. Evolution of cannulation techniques and anticoagulation strategies were defined. Morbidity during early and more recent experience was compared.

RESULTS

Deranged coagulation and excessive mediastinal bleeding were commonly observed in patients undergoing centrifugal mechanical assist for postcardiotomy cardiogenic shock. Evolved strategies to reduce blood loss included meticulous cannulation techniques, early use of blood components, and an aggressive policy of mediastinal reexploration. Thromboembolism occurred with centrifugal mechanical assist, was underestimated by clinical events, and dictated pursuit of improved anticoagulation strategies and device refinement. A clinically significant trend of decreasing morbidity from early to recent experience was observed.

CONCLUSIONS

Increasing clinical experience with centrifugal mechanical assist appears to result in a clinically relevant decrease in morbidity.

Role of hypertension in chronic renal allograft dysfunction

The damaging effects of essential hypertension and the central role of the kidney in its pathogenesis have long been recognized. Essential hypertension is the second leading cause of end-stage renal disease in the United States, with its prevalence increasing dramatically over the last decade. Similarly, the role of the transplanted kidney in the pathogenesis of hypertension has been demonstrated in animals and humans. Concerns over the inability of immunologic advancements to improve long-term allograft survival have focused attention on nonimmunologic factors, such as hypertension, and its contribution to chronic renal allograft injury. However, the complex nature of post-transplant hypertension has made it difficult to discern if its occurrence is the cause or the consequence of chronic allograft dysfunction. The possibility remains that, in many patients, the two processes are not mutually exclusive and coexist. Regardless, post-transplant hypertension negatively impacts long-term allograft and patient survival. Many questions regarding the etiology, optimal therapy and role of various growth factors in mediating the damaging effects of post-transplant hypertension remain unanswered and should serve as the focus for future studies.