Common Cause Of Graft Failure Research Articles

A porcine Model of Intimal-Medial Hyperplasia in Polytetrafluoroethylene Arteriovenous Grafts

Vascular access polytetrafluoroethylene (PTFE) graft failure is a major cause of morbidity in the hemodialysis population. The most common cause of graft failure is thrombosis secondary to stenosis at the venous outflow tract. Venous outflow stenosis is characterized by intimal-medial hyperplasia. We have developed a porcine arteriovenous (AV) graft model that may be used to investigate this proliferative response and aid in the development of new therapies to prevent intimal-medial hyperplasia and improve graft patency. Left carotid to right external jugular vein PTFE (6 mm) grafts were implanted in the necks of swine. Immediately following anatomosis, flow rates were recorded. In one group of animals (n = 4) the venous outflow tract was harvested after 7 days and morphometric analysis of intimal and medial area was performed. In a second group (n = 8) the graft patency was monitored until 28 days. All porcine PTFE fistula grafts were patent at 7 days and 100% patency was maintained until 14 days. After 28 days, 75% of the grafts failed due to thrombosis. The venous outflow tract developed a significant proliferative response. After 7 days the intimal and medial areas were 469 +/- 9 microm2 and 875 +/- 26 microm2 respectively. At 28 days the intimal and medial areas were 913 +/- 55 microm2 and 1437 +/- 182 microm2 respectively. Luminal flow rate of the venous outflow tract was reduced significantly (344 +/- 11 ml/min at Day 0 to 129 +/- 14 ml/min at Day 7, p < 0.05). This porcine model rapidly, reliably and robustly reproduces the flow reducing stenosis and intimal-medial hyperplasia at the venous outflow tract of PTFE arteriovenous fistula. It represents a promising tool for investigating the mechanisms of intimal-medial hyperplasia, evaluating therapeutic interventions and new graft materials.

Pretransplant peritoneal dialysis and graft thrombosis following pediatric kidney transplantation: a NAPRTCS report.

Graft thrombosis is a common cause of graft failure in pediatric renal transplantation. Several previous studies, including a North American Pediatric Renal Transplant Cooperative Study (NAPRTCS) review of pretransplant dialysis status and graft outcomes, have described a potential correlation of peritoneal dialysis (PD) and graft thrombosis. This issue is of particular concern for pediatric transplant programs as more than 65% of children with end stage renal disease are treated with PD. We reviewed 7247 pediatric renal transplants performed between 1987 and 2001. Thrombosis was the cause of graft loss in 2.7% (199) of all the transplants performed. Among failed transplants, thrombosis was the third most common cause of graft loss in both index (11.6%) and subsequent transplants (14.5%). Thrombosis becomes the most common cause of graft failure (21%, 61/294) if one looks at transplants in the later cohort, from 1996 to 2001. This change is primarily because of a decrease in the incidence of acute rejection. In the PD group, 3.4% of all grafts were lost as a result of thrombosis. This compares with 1.9% in the hemodialysis group, 2.4% in the pre-emptive transplant group, and 4.1% among patients who received both dialysis modalities. There was a statistically significant difference in thrombosis failure risk in the different dialysis groups (p = 0.005) with those who received only peritoneal dialysis having the highest risk. Additional significant risk factors for graft thrombosis included; cadaver donor source (p < 0.001), cold ischemia time >24 h (p < 0.001), history of prior transplant (p < 0.001), donor age <6 yr (p < 0.001), and >5 pretransplant blood transfusions (p = 0.02). Using stepwise proportional hazards modeling, only pretransplant peritoneal dialysis, >24 h cold ischemia time, prior transplant, and donor age <6 yr were simultaneously associated with an increased risk of thrombosis. We conclude that pretransplant PD is associated with an increased risk of graft thrombosis. Special precautions should be undertaken in pediatric renal transplant patients who have received PD, especially infants and young children.

Liver transplantation: the Italian experience

Background. Liver transplantation is the standard treatment for patients with end-stage liver disease no longer responsive to conventional medical treatment Aims. To report the longterm experience of liver transplantation in Italy. Patients and Methods. Data were obtained retrospective by means of a multiple-item form collected from 15 Italian liver transplant centres. The filing centre was centralized. Results. A total of 3323 liver transplants were performed on 3026 patients, with a cumulative proportional survival of 72.4%. Three, 5 and 10 years' patient survival rates were 72.3%, 68.8% and 61.3%, respectively. The most common indication for liver transplantation were hepatitis B virus (± hepatitis D virus)- and hepatitis C virus-related cirrhosis (59.4%). Excellent survival rates were observed particularly in controversial indications, such as alcoholic cirrhosis, hepatitis B virus-related cirrhosis and hepatocellular carcinoma. Retransplantation was required in 8.9% of the cases. The overall prevalence of acute cellular rejection episodes was 43.5%. In our study population, primary non-function and disease recurrence were the most common causes of graft failure (28.7% and 25.4%, respectively). Infections and/or sepsis were the most common causes of death after transplantation (42%). Conclusion. This study confirms that patients with controversial indications to liver transplantation such as alcoholic cirrhosis, HBV-related cirrhosis and hepatocellular carcinoma can achieve excellent survival when properly selected.

Visual rehabilitation and intraocular pressure elevation due to immunological graft rejection following penetrating keratoplasty

Endothelial graft rejection and intraocular pressure elevation are the most common causes of graft failure following penetrating keratoplasty (PK). Aim of this study was to evaluate the visual rehabilitation and the development of intraocular pressure during and after graft rejection. The study included 20 eyes of 20 patients (age 54.7 +/- 19.8 years) with endothelial graft rejection, that fulfilled the following inclusion criteria 1) graft rejection was diagnosed and treated in our department; 2) at least one year follow-up after graft rejection; 3) avascular corneal pathology. The mean follow-up was 23 +/- 14 months. According to the type of surgical procedure patients were classified in PK only (n = 15, one after cataract extraction), PK combined with extracapsular cataract extraction and intraocular lens (IOL) implantation (n = 1); PK combined with secondary IOL-implantation or IOL-exchange (n = 4). Standardized complete ophthalmological examinations were performed on a regular basis before, during the acute graft rejection und then regularly in a defined examination raster in an out-patient service with cornea specialization. The time interval between first symptom of 18 acute diffuse and 2 chronic focal graft rejection and start of treatment was 9 +/- 13 days. Best-corrected visual acuity (CVA) was 0.6 +/- 0.2 before graft rejection and decreased significantly at the time of diagnosis (0.2 +/- 0.2; p = 0.001). Six weeks after graft rejection CVA was 0.5 +/- 0.2 and remained almost stable until one year after rejection (0.6 +/- 0.3) in 16 patients with reversible graft rejection. Only 4 patients (20%) showed an irreversible graft failure requiring Re-PK. Intraocular pressure (IOP) was not elevated in 75% of the patients (n = 15) and did not need any antiglaucomatous treatment during and after the rejection phase. In 5 eyes (25%) (3 after PK combined with anterior chamber IOL-explantation and secondary posterior chamber IOL-implantation; 1 with secondary pseudoexfoliation glaucoma and 1 steroidal responder) IOP was elevated during graft rejection (26 +/- 7 mmHg), but was controlled by intensive topical antiglaucomatous treatment. Typically, the visual rehabilitation after graft rejection was good if the clinical signs were diagnosed just in time and treated adequately. There is no direct correlation between graft rejection and intraocular pressure elevation. However, the development of intraocular pressure elevation seems to be strongly associated with preexisting glaucoma, preexisting anterior synechiae and/or simultaneous anterior chamber lens implant removal. A careful patient management after PK plays an important role to prevent the development of irreversible graft failure due to graft rejection.

Arterial remodeling. Mechanisms and clinical implications.

The presentation of coronary atherosclerosis can be gradual, because of progressive flow-limiting stenosis and exertional angina, or dramatic, with plaque rupture and thrombosis causing unstable angina, myocardial infarction, or sudden death. The importance of arterial remodeling, or persistent change in vessel size, has recently become apparent in both situations. Arterial remodeling, not plaque size, has been identified as the primary determinant of lumen size in the presence of stable lesions. Similarly, luminal stenosis in transplant vasculopathy and with restenosis after angioplasty occur mainly because of inward remodeling rather than plaque growth. However, recent evidence also suggests that adequate outward remodeling may be associated with an increased risk of plaque rupture, the underlying cause of acute coronary syndromes and sudden cardiac death. The term “arterial remodeling” has previously been used to describe any change in vessel wall structure. More recently, however, it has been used specifically to refer to a change in vessel size (or cross-sectional area within the external elastic lamina), and it is on this entity that this review is focused. Inward remodeling denotes a reduction in vessel size. Outward remodeling denotes an increase in vessel size. Various other terms are used in the literature (the Table⇓). When outward remodeling is present but insufficient to prevent luminal stenosis, it is referred to as inadequate outward remodeling. View this table: Table 1. Terminology of Arterial Remodeling It has been known for more than a century1 that blood vessels enlarge to accommodate increasing flow to the organ downstream (eg, during natural growth or in left ventricular hypertrophy). Widespread interest in this phenomenon was stimulated by observations that radial enlargement of vessels (outward remodeling) can compensate for progressive growth of atherosclerotic plaques, thus postponing the development of flow-limiting stenosis.2 3 These pathological findings were subsequently supported by in vivo intravascular ultrasound (IVUS) studies that …

KIDNEY TRANSPLANTATION IN CHILDREN: A SINGLE CENTER EXPERIENCE

Purpose We reviewed our most recent 10-year experience with kidney transplantation in children to determine the morbidity and mortality of the procedure, and to identify factors that affected outcome. Materials and Methods A total of 107 renal transplants were done in 95 children 1 to 17 years old (mean age 10.9) during the 10-year period ending January 1, 1997. The 4 most common causes of end stage renal disease were renal dysplasia, reflux nephropathy, obstructive uropathy and systemic immunological diseases. Cyclosporine based immunosuppression was used in all but 2 recipients. After April 1991 antilymphocyte antibody induction, coagulopathy screening, systemic anticoagulation and cytomegalovirus prophylaxis were incorporated into the protocols. The effects of kidney source, recipient gender, recipient age, preformed anti-HLA antibody level, preemptive renal transplantation, cytomegalovirus risk, antilymphocyte antibody induction therapy and date of renal transplantation on kidney graft survival were examined with the log rank test. Results The 1-year graft and patient survival rates were 91 and 99%, respectively. The most common causes of graft failure were rejection and recurrence of primary renal disease. The only factors that significantly (p <0.05) influenced graft survival were antilymphocyte antibody induction immunosuppression and kidney transplantation after April 1991. Three urological complications required surgical correction. Medical morbidity included hypertension in 48.6% of the cases, short stature in 46.6% and obesity in 58.9%. Conclusions Pediatric renal transplantation can be done with acceptable morbidity, a low rate of technical complications and low mortality. Hypertension, chronic rejection and abnormal body habitus continue to be problematic.

Prevention of Anastomotic Intimal Hyperplasia in Infrainguinal PTFE Bypass Grafts with Distal Arterial Segment Interposition

Anastomotic intimal hyperplasia (AIH) is a common cause of graft failure after femoropopliteal polytetrafluoroethylene (PTFE) bypass. Compliance mismatch between the PTFE graft and the native artery may be a significant factor causing AIH. This study examines whether reduction of compliance mismatch by interposition at the distal anastomosis of a segment of superficial femoral artery after eversion endarterectomy could reduce or eliminate AIH and improve graft patency. Between July 1989 and June 1996, PTFE grafts with a distal arterial segment (AS) were used to revascularize 51 limbs in 45 patients (12 men and 33 women). Twenty-five grafts were above-knee (AK) and 26 below-knee (BK). Disabling claudication was the indication in 32 limbs (AK 20, BK 12) and limb-threatening ischemia in 19 (AK 5, BK 14). Physical examination, measurement of ankle-brachial index, and duplex scanning were used to follow up patients at regular intervals. For those patients who had recurrent symptoms and/or reduction of ankle/brachial index (ABI), arteriography was performed. Follow-up ranged from 1-54 months (mean 20 months) for AK grafts and 1-76 months (mean 19 months) for BK grafts. The overall primary patency rate at 4.5 years was 57.2%. There appears to be no significant difference between AK and BK primary patency survival distributions (64.8% vs 48.5%). The primary patency failure distributions for the two ischemic conditions are statistically significant (69.8% vs 31.9%). The limb salvage rate at 4.5 years was 80%. Of the 51 grafts, the causes of the 19 failures included progression of disease in eight, thromboembolus in three, stenosis of the AS in three, poor runoff in one, AIH at the proximal anastomosis in one, and unknown in three. This pilot study suggests that the femoropopliteal PTFE bypass with distal AS interposition provides improved graft patency and limb salvage rates when compared with those published in the literature for PTFE bypass without the AS. Further evaluation is warranted.

Chronic in vitro shear stress stimulates endothelial cell retention on prosthetic vascular grafts and reduces subsequent in vivo neointimal thickness

Objective: The absence of endothelial cells at the luminal surface of a prosthetic vascular graft potentiates thrombosis and neointimal hyperplasia, which are common causes of graft failure in humans. This study tested the hypothesis that pretreatment with chronic in vitro shear stress enhances subsequent endothelial cell retention on vascular grafts implanted in vivo. Methods: Cultured endothelial cells derived from Fischer 344 rat aorta were seeded onto the luminal surface of 1.5-mm internal diameter polyurethane vascular grafts. The seeded grafts were treated for 3 days with 1 dyne/cm 2 shear stress and then for an additional 3 days with 1 or 25 dyne/cm 2 shear stress in vitro. The grafts then were implanted as aortic interposition grafts into syngeneic rats in vivo. Grafts that were similarly seeded with endothelial cells but not treated with shear stress and grafts that were not seeded with endothelial cells served as controls. The surgical hemostasis time was monitored. Endothelial cell identity, density, and graft patency rate were evaluated 24 hours after implantation. Endothelial cell identity in vivo was confirmed with cells transduced in vitro with β-galactosidase complementary DNA in a replication-deficient adenoviral vector. Histologic, scanning electron microscopic, and immunohistochemical analyses were performed 1 week and 3 months after implantation to establish cell identity and to measure neointimal thickness. Results: The pretreatment with 25 dyne/cm 2—but not with 0 or 1 dyne/cm 2—shear stress resulted in the retention of fully confluent endothelial cell monolayers on the grafts 24 hours after implantation in vivo. Retention of seeded endothelial cells was confirmed by the observation that β-galactosidase transduced cells were retained as a monolayer 24 hours after implantation in vivo. In the grafts with adherent endothelial cells that were pretreated with shear stress, immediate graft thrombosis was inhibited and surgical hemostasis time was significantly prolonged. Confluent intimal endothelial cell monolayers also were present 1 week and 3 months after implantation. However, 1 week after implantation, macrophage infiltration was observed beneath the luminal cell monolayer. Three months after the implantation in vivo, subendothelial neointimal cells that contained α–smooth muscle actin were present. The thickness of this neointima averaged 41 ± 12 μm and 60 ± 23 μm in endothelial cell–seeded grafts that were pretreated with 25 dyne/cm 2 shear stress and 1 dyne/cm 2 shear stress, respectively, and 158 ± 46 μm in grafts that were not seeded with endothelial cells. Conclusion: The effect of chronic shear stress on the enhancement of endothelial cell retention in vitro can be exploited to fully endothelialize synthetic vascular grafts, which reduces immediate in vivo graft thrombosis and subsequent neointimal thickness. (J Vasc Surg 1999;29:157-67.)

Histologic grading of acute allograft rejection in pancreas needle biopsy: correlation to serum enzymes, glycemia, and response to immunosuppressive treatment.

Allograft rejection continues to be the most common cause of graft failure in technically successful pancreas transplants. Early diagnosis and treatment of rejection is essential for long-term graft survival. Pancreas graft biopsies are now used routinely for the diagnosis of acute allograft rejection. The correlation between clinical evidence of graft dysfunction (increased serum enzymes and glucose), severity of acute rejection on biopsy (rejection grade), and response to treatment has not been previously studied. A total of 151 pancreas transplant needle biopsy specimens from 57 patients were evaluated. Statistical correlation was done between the histologic rejection grade (O-V) and the peak level of enzymes in serum, glycemia, type of antirejection treatment instituted, and response to treatment. Differentiation between grades was also evaluated statistically. Response to antirejection treatment was 25%, 40%, 88%, 78%, 50%, and 17% for grades O-V, respectively. The response for grades II and III was better than for grades 0-I and IV-V (P=0.0003 and 0.0008, respectively). The response to corticosteroids alone was 36%, 86%, 68%, and 0% for grades I, II, III, and IV, respectively. The response to antilymphocyte regimen was 50%, 89%, 85%, 71%, and 17% for grades I, II, III, IV, and V, respectively. Overall correlation between the mean levels of enzymes and rejection grade was seen; the increase of lipase was statistically significant (r=0.24, P=0.012). Amylase and lipase correlated very well with each other (r=0.84, P=0.0001). No correlation was found in the mean values of blood glucose with the serum enzyme increase and with severity of rejection. Hyperglycemia was present in 12 patients; this abnormality in patients with grades II-IV responded promptly to treatment, whereas in patients with grade V, hyperglycemia persisted despite antirejection treatment. Other causes of increased enzymes were found in patients with biopsy specimens showing no rejection (grades 0 and I, 43% and 31%, respectively). Increased serum enzymes, particularly lipase, correlate with the grade of acute rejection, but their lack of specificity precludes their use as sole markers of acute rejection. Glucose levels are not a sensitive marker for acute rejection. Rejection grades II and III are the most responsive to treatment, and a significant proportion of these cases respond to treatment with corticosteroids only. The higher rejection grades (IV and V) require treatment with antilymphocytic regimens, and their overall response to treatment is moderate to poor, respectively.

Clinical Results of Infrainguinal Bypass Using Plasma TFE™ Vascular Graft

Twenty-eight infrainguinal bypasses using woven polyethylene terephthalate (PET) vascular graft coated with tetrafluoroethylene (TFE) were evaluated. Distal graft anastomoses were performed to the above-the-knee (AK) popliteal artery in 18 limbs, belowthe-knee (BK) popliteal artery in three limbs, and tibial arteries in seven limbs. No early graft occlusions (within 30 days) occurred in femoropopliteal (FP) bypasses, whereas 5/7 (71%) femorotibial (FT) bypasses occluded postoperatively within five days. During 3 years of follow up, 11 occluded and six failing grafts were detected in the FP bypass group. Average patency times for AK FP, BK FP, and FT bypasses were 619.0 4.5, 226.0 ± 23.0, and 43.4 ±4.5 days, respectively. The cumulative patency rates for AK FP bypass were 81.6 ±.6% at 8 months and 66.7 ±12.3% at 1 year. Seventeen limbs with occluded or failing grafts disclosed six anastomotic stenoses in five (29%) grafts, occlusive lesions in three (18%) inflow and three (18%) outflow host arteries, and thrombosis of two (12%) inflow bypass grafts. No significant lesions were detected in four (23%) occluded grafts following thrombolytic therapy. The results indicated that this graft has acceptable antithrombogenicity in FP position because of no early graft occlusion, and the common causes of graft failure were anastomotic stenoses and occlusive lesions of the host artery.

Impact of inflow reconstruction on infrainguinal bypass

Purpose: This study assessed whether multisegmental disease that is severe enough to require an inflow procedure adversely affects infrainguinal bypass patency, limb salvage, or patient survival rates. Methods: The records of 495 patients who underwent 551 infrainguinal bypass grafting procedures were reviewed. Saphenous vein and prosthetic grafts were evaluated separately. Graft patency rates, patient limb salvage rates, and patient survival rates in those grafts that arose from a reconstructed inflow source were compared with those that arose from normal, nonreconstructed inflow sources. When grafts had either hemodynamic failure or occlusion, the cause of failure was identified. Results: Four-year primary patency rates in vein grafts that arose from a reconstructed inflow sources were lower than those in grafts that arose from nonreconstructed inflow sources (41% vs 54%; p = 0.006). Assisted primary patency rates and secondary patency rates, however, were similar (62% vs 74% and 64% vs 77%, respectively). The 4-year primary patency rate (45% vs 55%), assisted primary patency rate (60% vs 60%), and secondary patency rate (60% vs 61%) in prosthetic grafts did not vary based on inflow source. The most common cause of graft failure was inflow failure, except in the vein grafts that did not require an inflow procedure, in which the most common cause of failure was graft failure. Inflow failure occurred in 24% and 22% of the vein and prosthetic grafts with multisegmental disease, respectively, but in only 7% ( p < 0.001) and 10% ( p < 0.05), respectively, of those that arose from normal nonreconstructed inflow. The presence of an inflow procedure did not affect limb salvage rates or patient survival rates, regardless of graft material. Conclusions: Long-term patency rates, patient limb salvage rates, and survival rates in patients with a reconstructed inflow source were similar to those of patients with a normal nonreconstructed inflow. A major cause of occlusion is inflow failure, and this occurs in a greater proportion of patients with multisegmental disease. These patients, in particular, may benefit from patient surveillance to screen for progression of their inflow disease and to allow for intervention before infrainguinal graft occlusion. (J Vasc Surg 1997;26:928-38.)

How successful is corneal transplantation? A report from the Australian Corneal Graft Register.

Corneal graft outcome was assessed within a large, prospectively collected database of 4499 records. Penetrating corneal graft survival was 91% at 1 year, 72% at 5 years and 69% at 7 years. The three most common indications for graft were keratoconus (30%), bullous keratopathy (25%) and failed previous graft (18%); the three most common causes of graft failure were rejection (34%), infection (18%) and glaucoma (9%). The vast majority of grafts were performed for improved visual acuity. About four-fifths of recipients achieved at least one line of better acuity on the Snellen chart post-operatively; of the remainder with unchanged or worse acuity, only 21% had failed grafts. Overall, 43% of recipients achieved a best corrected Snellen acuity of 6/12 or better, 52% achieved 6/18 or better, and 20% had acuitities of less than 6/60. Reasons for poor post-operative acuity (recorded as less than 6/60) included graft failure (41%) and comorbidities in the grafted eye (43%). A number of risk factors for graft failure were examined: in most instances, there was little room for decision-making or expert intervention.

Effect of prolonged delayed graft function on long‐term graft outcome in cadaveric kidney transplantation

One‐hundred‐and‐twenty‐six cadaveric renal transplantations were analyzed for the effect of post‐transplant renal function on graft outcome. Thirty‐one grafts functioned immediately after transplantation (Group 1), 54 grafts failed to function temporarily up to 8 posttransplant days as evidenced by urine output &lt;400 ml/day or hemodialysis support (Group 2), 33 grafts showed temporary nonfunction &gt;8 days (Group 3) and 8 grafts never functioned (group 4). Five‐year graft failure rates were 6.5% (2/31), 13.0% (7/54). 42.4% (14/33) and 100% (8/8) for Groups 1. 2, 3 and 4, respectively. Actuarial 5‐year graft survivals were 89.4%. 84.8%. 50% and 0% for Groups 1. 2, 3 and 4, respectively (p&lt;0.05). The most common cause of graft failure was the chronic rejection in 13, of which 9 were in Group 3. Acute rejection episodes during the first 3 months post‐transplant in Group 3 (15 of 33, 45.5%) was slightly higher than that in Group 1 (10 of 30. 33.3%) or Group 2 (19 of 54. 35.2%) but the differences were not significant. Acute rejection episodes were associated with graft loss only 1 of 19 (5.3%) patients in Group 2 whereas 9 of 15 (47.4%) were seen in Group 3. The authors conclude that prolonged DGF is associated with a higher incidence of graft failure, particularly secondary to chronic rejection after 1 year posttransplant. Moreover, acute rejection based on prolonged DGF probably plays a major role in the development of chronic rejection.

Surveillance of infrainguinal vein grafts with duplex sonography.

This review considers the relative roles of traditional noninvasive vascular tests and conventional duplex and color flow Doppler sonography in the surveillance of infrainguinal autologous vein grafts. The purpose of surveillance is to identify significant anatomic or flow abnormalities that predispose to thrombosis, but can be repaired before graft thrombosis occurs. Although a few authors believe that serial measurements of the ankle-brachial index and other noninvasive vascular tests can serve as the primary method of surveillance for infrainguinal grafts, most authors do not concur. After the first postoperative month, stenosis caused by intimal hyperplasia is the most common cause of graft failure, usually occurring within 18 months after placement. Duplex sonography is both highly sensitive and specific for detection of such stenoses. Specific duplex sonographic criteria have been established for grading of stenoses and for the diagnosis and classification of arteriovenous fistulas. A large body of evidence suggests that graft thrombosis can occur without prior warning symptoms and that long-term graft patency improves if the asymptomatic lesions detected with duplex sonography are repaired before symptoms develop.

Five-year corneal graft survival. A large, single-center patient cohort.

To determine the survival rates and causes of secondary graft failure in a large, consecutive series of penetrating keratoplasties. All eyes undergoing penetrating keratoplasty at a single center were evaluated for factors relating to penetrating keratoplasty preoperatively, surgically, and postoperatively at 1, 3, 6, 9, 12, 18, and 24 months and then at yearly intervals. Since 1986, data analysis has been prospective. A large, private practice, tertiary center for corneal disorders and surgery. A consecutive series of 1819 penetrating keratoplasties performed from August 1982 through August 1990; 13 eyes with primary graft failure were excluded. Graft failure and causes of failure. Follow-up ranged from 1 to 96 months, with a mean of 26.6 months. Pseudophakic bullous keratopathy was the most common diagnosis necessitating keratoplasty (38.6%). Secondary failures occurred 111 times (6.1%). The 2- and 5-year survival rates for all grafts in the study were 95% and 91%, respectively. While endothelial failure as a result of immunologic allograft reactions was the most common cause of graft failure (27%), problems with the external surface of the graft caused nearly as many failures (25%). The risk of failure from surface-related problems was highest at 3 months after surgery. There were significantly decreased survival rates for grafts in eyes with regrafts (P < .0001), in eyes left aphakic at keratoplasty (P < .0001), and in eyes with deep stromal vascularization (P < .0001). Penetrating keratoplasty is a successful form of transplantation, and survival rates are gradually increasing. The risk of graft failure appears highest within the first year after transplantation.

Patient and renal allograft survival in the late posttransplant period.

Finding the proper balance between too much and not enough immunosuppression is just as important in the late posttransplant period as it is during the first year after transplantation. In general, too much immunosuppression leads to an increase in patient mortality, whereas inadequate immunosuppression can lead to an inordinately high rate of allograft failure (Fig 5). In the late posttransplant period, patient and allograft survival are both critically dependent on the degree of immunosuppression and on the long-term side effects of the agents used to achieve this immunosuppression. Adequate immunosuppression is important in treating and preventing the acute allograft rejection episodes that are common during the first year after transplantation (Fig 6). Some data suggest that the severity of early acute rejection episodes may influence the development of chronic rejection, the most common cause of graft failure in the late posttransplant period. Otherwise, the role of immunosuppression in treating and preventing chronic rejection is unclear. The discontinuation of immunosuppression by noncompliant patients is a major cause of late graft failure. Whether the nephrotoxicity of CsA will also result in graft failure in the very late posttransplant period is still unknown. The agents used to achieve immunosuppression, along with decreased graft function and proteinuria, contribute to hypercholesterolemia, hypertension, and hyperglycemia. These and other risk factors have a negative impact on both graft and patient survival. Thus, immunosuppression is directly, or indirectly linked to most of the common causes of death and graft failure after renal transplantation. Although potent new immunosuppression protocols have increased the rate of short-term patient and allograft survival after renal transplantation, future advances in long-term survival after renal transplantation will depend on improvements that are effective in the late posttransplant period. Currently, the best approach to preventing complications in the late posttransplant period is to maintain a vigilant, comprehensive program of on-going medical care. The minimal amount of immunosuppression required to prevent allograft rejection should be used, while adhering to the principle that it is better to lose the graft than to lose the patient.

Factors Predictive of Corneal Graft Survival: Report from the Australian Corneal Graft Registry

Risk factors for graft failure after penetrating keratoplasty were investigated in 961 patients from records collected prospectively by the Australian Corneal Graft Registry. The most common cause of graft failure was irreversible rejection. A multivariate proportional hazards regression analysis indicated that the key predictors of graft failure were: an indication for graft other than keratoconus or corneal dystrophy; a failed previous graft (ipsilateral eye); aphakia; inflammation at the time of graft; presence of an anterior chamber or iris-clip intraocular lens; graft size outside the range of 7.0 to 7.9 mm diameter; and corneal vascularization occurring in the postoperative period.

Arthroscopic "second look" at the GORE-TEX ligament.

We performed an arthroscopic "second look" in 21 knees (20 patients) that had arthroscopic implantation of the GORE-TEX prosthesis for chronic ACL insufficiency. Arthroscopy was done on eight knees at the time of screw removal, eight for knee pain, two for giving way, and three for recurrent effusions. The degree of synovial joint reaction, graft synovial ingrowth, and graft rupture was graded. Microscopic examination was carried out on all biopsies of the GORE-TEX ligament. The average patient age was 30 years and the average time interval from original implantation to second look was 11 months. The GORE-TEX was intact in 11 knees, 10% ruptured in 6, and completely ruptured in 4. There was no correlation between number of GORE-TEX strands ruptured and synovial reaction. No particles of the graft were noted in the synovium if the implant was intact, but particles were noted with graft rupture. We conclude that the intact GORE-TEX ligament is an inert substance and does not cause significant joint reaction. Impingement in the intercondylar notch appeared to be the most common cause of graft failure. Further study is critical to determine the natural history of the GORE-TEX ligament and the knees' response to this prosthetic device.

Survival of Corneal Grafts from Donors Supported by Mechanical Ventilation

Eighty-five patients undergoing penetrating keratoplasty with tissue from donors supported by mechanical ventilation (Ventilator group) were compared to a surgeon- and diagnosis-matched group (Control group). Age at surgery, duration of follow-up, and sex of recipient patients were similar in the two groups. The mean donor age in the Ventilator group (26.4 years) was significantly less than in the Control group (45.8 years, P < 0.0001). Mean time on the ventilator was 99.4 hours (range, 4 hours to 21 days). Overall graft survival rates in the Ventilator and Control groups were similar (P ≥ 0.72). Time on the ventilator did not affect graft survival. Cultures of corneoscleral donor rims were positive more often in the Ventilator group than in Controls (39.7 versus 23.1 %), but the difference was not significant (P = 0.09). Prolonged ventilator time was not associated with a higher rate of positive coneoscleral rim cultures, nor did positive cultures affect graft survival. The most common cause of graft failure in both groups was allograft rejection. In no case could postoperative bacterial infection be attributed to contamination of the donor material. One case of primary donor failure occurred in the Ventilator group, but the incidence (1.2%) is similar to that of previously reported studies. The data indicate that corneal tissue from ventilator-supported donors should be considered for use in penetrating keratoplasty.

Wound Drainage from Under Full‐thickness Skin Grafts in Dogs Part I. Quantitative Evaluation of Four Techniques

The formation of hematomas or seromas under skin grafts is reported to be the most common cause of graft failure. Several techniques have been developed to prevent fluid accumulation by increasing drainage, but their effectiveness has not been evaluated. In this study, four full‐thickness skin grafting procedures were performed on both sides of the chests of 12 dogs, and the amount of wound drainage was quantitated for the first 10 postoperative days. The techniques evaluated were a sheet graft (control), continuous low level suction, piecrust incisions, and nonexpanded mesh graft. Significantly more drainage fluid was removed by continuous low level suction than the other techniques evaluated. Meshing allowed significantly more drainage than the piecrust or sheet grafts but was not as effective as continuous low level suction. Piecrust incisions had no significant effect on wound drainage.