Robert J. Hye

Relationship of age, gender, race, and body size to infrarenal aortic diameter

PURPOSE To assess the effects of age, gender, race, and body size on infrarenal aortic diameter (IAD) and to determine expected values for IAD on the basis of these factors. METHODS Veterans aged 50 to 79 years at 15 Department of Veterans Affairs medical centers were invited to undergo ultrasound measurement of IAD and complete a pre-screening questionnaire. We report here on 69,905 subjects who had no previous history of abdominal aortic aneurysm (AAA) and no ultrasound evidence of AAA (defined as IAD > or = 3.0 cm). RESULTS Although age, gender, black race, height, weight, body mass index, and body surface area were associated with IAD by multivariate linear regression (all p < 0.001), the effects were small. Female sex was associated with a 0.14 cm reduction in IAD and black race with a 0.01 cm increase in IAD. A 0.1 cm change in IAD was associated with large changes in the independent variables: 29 years in age, 19 cm or 40 cm in height, 35 kg in weight, 11 kg/m2 in body mass index, and 0.35 m2 in body surface area. Nearly all height-weight groups were within 0.1 cm of the gender means, and the unadjusted gender means differed by only 0.23 cm. The variation among medical centers had more influence on IAD than did the combination of age, gender, race, and body size. CONCLUSIONS Age, gender, race, and body size have statistically significant but small effects on IAD. Use of these parameters to define AAA may not offer sufficient advantage over simpler definitions (such as an IAD > or = 3.0 cm) to be warranted.

Animal models of diabetes mellitus: Physiology and pathology

Abstract Contents. I. Introduction. II. Chemically induced diabetes in animals . A. Alloxan. B. Streptozotocin. C. Biochemistry of chemically induced diabetes. D. Pathology of chemically induced diabetes. 1. Pancreatic pathology. 2. Renal pathology. 3. Ocular pathology. 4. Nerve pathology. III. Spontaneous diabetes in animals . A. The Chinese hamster. B. The BB/W rat. C. The db and ob mouse. D. The guinea pig. E. Macaca nigra. F. Additional models of spontaneous diabetes. IV. Virus-induced diabetes in animals .

Ischemic Monomelic Neuropathy: An Under-Recognized Complication of Hemodialysis Access

During the past 3 years six episodes of ischemic monomelic neuropathy (IMN) have been identified in five patients as a complication of upper extremity dialysis grafts. All patients had long-standing insulin-dependent diabetes, peripheral neuropathy, and brachial artery graft origins, whereas 60% had peripheral vascular disease. Five episodes occurred immediately after graft placement, whereas one was due to a graft-related thromboembolus. Diagnostic delay was common with initial findings attributed to anesthesia, positioning, or surgical trauma. Electrophysiologic studies showed underlying diabetic neuropathy with severe multifocal neuropathy distal to the grafts. Digital pressure indices were reduced but there was no critical ischemia. In three cases ischemia was completely corrected with improvement in one. One patient had proximal balloon angioplasty with no improvement and of the two untreated patients, one improved slightly. Ischemic monomelic neuropathy is a rare but disabling complication of dialysis access in diabetic uremic patients. Its occurrence is unpredictable and diagnostic delay is common. Correction of ischemia is indicated but usually does not improve the neuropathy. Prevention requires further research to more accurately characterize the patients at risk.

Randomized trial of emergency endoscopic sclerotherapy versus emergency portacaval shunt for acutely bleeding esophageal varices in cirrhosis.

BACKGROUND The mortality rate of bleeding esophageal varices in cirrhosis is highest during the period of acute bleeding. This is a report of a randomized trial that compared endoscopic sclerotherapy (EST) with emergency portacaval shunt (EPCS) in cirrhotic patients with acute variceal hemorrhage. STUDY DESIGN A total of 211 unselected consecutive patients with cirrhosis and acutely bleeding esophageal varices who required at least 2 U of blood transfusion were randomized to EST (n=106) or EPCS (n=105). Diagnostic workup was completed within 6 hours and EST or EPCS was initiated within 8 hours of initial contact. Longterm EST was performed according to a deliberate schedule. Ninety-six percent of patients underwent more than 10 years of followup, or until death. RESULTS The percent of patients in Childs risk classes were A, 27.5; B, 45.0; and C, 27.5. EST achieved permanent control of bleeding in only 20% of patients; EPCS permanently controlled bleeding in every patient (p< or =0.001). Requirement for blood transfusions was greater in the EST group than in the EPCS patients. Compared with EST, survival after EPCS was significantly higher at all time intervals and in all Childs classes (p< or =0.001). Recurrent episodes of portal-systemic encephalopathy developed in 35% of EST patients and 15% of EPCS patients (p< or =0.01). CONCLUSIONS EPCS permanently stopped variceal bleeding, rarely became occluded, was accomplished with a low incidence of portal-systemic encephalopathy, and compared with EST, produced greater longterm survival. The widespread practice of using surgical procedures mainly as salvage for failure of endoscopic therapy is not supported by the results of this trial (clinicaltrials.gov #NCT00690027).

Is thrombolysis of occluded popliteal and tibial bypass grafts worthwhile

PURPOSE We analyzed the short- and long-term results for patients undergoing thrombolysis of occluded infrainguinal bypass grafts at our institution over a 62-month period. METHODS Thirty-one patients with 40 episodes of graft thrombosis in 33 grafts managed by thrombolysis were retrospectively reviewed. The effects of graft age, material, and anatomy, symptoms, treatment, anticoagulation, and occlusion duration were evaluated for impact on patency after thrombolysis. Dose and duration of therapy with use of the technique of pulse-spray thrombolysis was assessed. RESULTS Thrombolysis successfully reestablished patency in 92% of grafts treated. Mean lysis time and urokinase dose were 118 minutes and 607,000 units, respectively. Responsible lesions were identified and treated by angioplasty or surgery in 35 of 37 cases. The patency rate after thrombolysis was 28% at 30 months, and the secondary patency rate was 46% at 18 months. Duration of occlusion, symptoms, treatment, graft anatomy, and prior graft revision did not impact on patency. Mean secondary patency was 21.5 months in grafts in place over 1 year and 7.0 months in grafts in place for less than 1 year. Mean secondary patency was 23.8 months in polytetrafluoroethylene grafts and 8.4 months in vein grafts. The limb salvage rate was 84% at 30 months, and the patient survival rate was 84% at 42 months. CONCLUSIONS Pulse-spray thrombolysis is effective in rapidly recanalizing thrombosed infrainguinal grafts. Grafts failing in the first year after placement should generally be replaced, reserving thrombolysis and revision for grafts greater than 1 year old. Vein grafts tolerate thrombosis less well than synthetic conduits and have decreased long-term patency.

Midterm results of a novel technique to salvage autogenous dialysis access in aneurysmal arteriovenous fistulas

PURPOSE Over the last decade, K-DOQI guidelines have increasingly emphasized the importance of autogenous arteriovenous fistulas (AVF) for dialysis access. A complication of AVF is aneurysmal dilatation with a subset developing massive diffuse aneurysm. Treatment of massive aneurysmal AVF generally involves either ligation or resection with use of prosthetic interposition. To maintain an all-autogenous access, we developed a procedure to treat massive aneurysmal AVF in which the luminal diameter is reduced, excess length is resected, and the new reconstructed AVF is re-tunneled for continued use. The purpose of this study is to examine the midterm outcomes of this novel procedure. METHODS Over a 4-year period, the reduction/revision procedure was performed on 19 patients with an AVF diameter of 4-7 cm. Indications for operation were thrombosis, skin breakdown, infection, bleeding, and/or poor flow. Revision was performed by resecting redundant length, reducing diameter, and then reconstructing the fistula. RESULTS The median patient age was 47, interquartile range (IQR) 29. There were 13 men and 6 women. The median follow-up was 23 months, IQR 22. The median primary patency was 14 months, IQR 24. The median secondary patency was 16.5 months, IQR 26. Two patients died, one AVF thrombosed, and two were ligated secondary to infection. Three fistulae developed a stenosis that was treated with percutaneous angioplasty. There are no recurrent aneurysms to date. CONCLUSION Surgical resection of excess length, reduction of luminal diameter, and reconstruction is a viable option for the treatment of complicated massive diffusely aneurysmal AVF. This technique offers the ability to maintain the benefits of an all autogenous dialysis access while conserving future dialysis sites.

Hemodialysis-Related Steal Syndrome: Predictive Factors and Response to Treatment with the Distal Revascularization-Interval Ligation Procedure

Hand ischemia due to steal causes major disability in affected members of the hemodialysis population. Between February 2000 and March 2007, 24 patients aged 37-77 years were identified who developed hand ischemia distal to a hemodialysis access and required a distal revascularization-interval ligation (DRIL) procedure. Of the 24 patients, 22 (92%) were diabetic, 14 (58%) were women, 7 (29%) had prosthetic grafts, and 17 (71%) had fistulas, all originating from the brachial artery. Duration between the initial dialysis access and the DRIL procedures ranged 12 hours to 10 months. Conduits used were saphenous vein in 13 (54%) cases, cephalic vein in 3 (12%) cases, basilic vein in 5 (21%) cases, and prosthetic grafts in 3 (12%) cases. There were no operative deaths. Improved blood flow and relief of symptoms were observed in 23 (96%) patients. The procedure failed early in one patient who had thrombosis of a prosthetic graft. Two patients required digital amputations. At a median follow-up of 50 months, 14 (58%) patients died using the access requiring the DRIL, 2 (8%) did not require dialysis, 3 (12%) were using a new access, and 5 (21%) were still using the access that had required the DRIL. In late follow-up, only one DRIL bypass required revision and the remainder were patent. One patient developed an ischemic hand 5 years after his DRIL procedure despite a patent bypass. The development of ischemic steal requiring performance of a DRIL procedure is most likely to occur in diabetic patients with dialysis access originating from the brachial artery. The procedure is effective in ameliorating symptoms while preserving the vascular access. The high long-term mortality rate observed in this series underscores the fact that patients requiring a DRIL procedure represent a subset of dialysis patients with advanced diabetic vascular disease and a limited life expectancy. Despite the effectiveness of the DRIL procedure, efforts should be concentrated on prevention of ischemic steal in order to lessen the morbidity and expense of this condition in the dialysis population.

Pulse-spray pharmacomechanical thrombolysis for treatment of thrombosed dialysis access grafts

The results of pulse-spray pharmacomechanical thrombolysis (PSPMT) of 209 thrombosed hemodialysis grafts were reviewed. In PSPMT, concentrated urokinase is injected forcefully through catheters with multiple tiny sideholes or sideslits. Catheters placed in a crisscross fashion cover the entire clot simultaneously. This therapy was successful in treating patients with thrombosed grafts. Of the 200 grafts with complete therapy, 197 grafts (99%) were patent at the end of the procedure. Mean time for pulsed-spray lysis was 40 minutes. Etiologies for graft thrombosis were anastomotic venous outflow stenosis, stenosis of the venous outflow away from the anastomosis, arterial stenosis, intragraft stenosis, pseudoaneurysms, and no identifiable cause in a small percentage. There were 16 complications, 8 of which required additional therapy or potentially compromised the graft. These results suggest that pharmacomechanical thrombolysis and angioplasty provide rapid, consistent, and safe recanalization of thrombosed hemodialysis grafts and represent an additional therapeutic approach to graft management.

Portal-systemic encephalopathy in a randomized controlled trial of endoscopic sclerotherapy versus emergency portacaval shunt treatment of acutely bleeding esophageal varices in cirrhosis.

Background:In patients with cirrhosis and bleeding esophageal varices, there is a widespread belief that control of bleeding by portal-systemic shunts is compromised by a high incidence of shunt-related portal-systemic encephalopathy (PSE). This important issue was examined by a randomized controlled trial that compared emergency and long-term endoscopic sclerotherapy (EST) to emergency direct portacaval shunt (EPCS) in patients with cirrhosis and acute variceal hemorrhage. Methods:The study was a community-wide undertaking known as the San Diego Bleeding Esophageal Varices Study. A total of 211 unselected, consecutive patients with biopsy-proven cirrhosis and endoscopically proven, acutely bleeding esophageal varices that required at least 2 units of blood transfusion were randomized to EST (n = 106) or EPCS (n = 105). The diagnostic workup was completed in less than 6 hours and EST or EPCS was initiated within 8 hours of initial contact. Long-term EST was performed according to a deliberate schedule over months. Criteria for failure of EST or EPCS were clearly defined and crossover rescue treatment was applied, whenever possible, when failure of primary therapy was declared. PSE was quantitated by a “blinded” senior faculty gastroenterologist. Four variously weighted components of PSE were graded on a scale of 0 to 4: (1) mental state, (2) asterixis, (3) number connection test, and (4) arterial blood ammonia. PSE was classified as recurrent if 2 or more episodes were documented. All patients (100%) had follow-up for more than 9.4 years or until death. Results:Childs risk classes in the EST and EPCS groups, respectively, were 25% and 30% in class A, 43% and 47% in class B, and 26% and 29% in class C. Mean time from onset of bleeding to EST or EPCS was less than 24 hours, and from study entry to EST or EPCS was 3.1 to 4.4 hours, respectively. EST achieved permanent control of bleeding in only 20% of patients, while EPCS permanently controlled bleeding in every patient (P ⩽ 0.001). Survival following EPCS was 3.5 to 5 times greater than that of EST at 5, 10, and 15 years (P ⩽ 0.001). The incidence of recurrent PSE following EST (35%) was more than twice the incidence following EPCS (15%) (P ⩽ 0.001). EST patients had a total of 179 episodes of PSE and 146 PSE-related hospital admissions, compared with EPCS patients who had 94 episodes of PSE and 87 hospital admissions (P ⩽ 0.001). Recurrent upper gastrointestinal bleeding, which was rare in the EPCS group, was a major causative factor of PSE in the EST patients. Conclusions:In contrast to EST, EPCS permanently controlled variceal bleeding, resulted in significantly greater long-term survival, and was followed by a relatively low (15%) incidence of PSE. These results were facilitated by rigorous, frequent, and lifelong follow-up that included regular counseling on dietary protein restriction and abstinence from alcohol, and by long-term patency of the portacaval shunt in 98% of patients. Furthermore, these results call into question the practice of avoiding portacaval shunt because of fear of PSE, and thereby foregoing the lifesaving advantage achieved by surgical control of bleeding. (clinicaltrials.gov NCT00690027)

The contemporary management of renal artery aneurysms

BACKGROUND Renal artery aneurysms (RAAs) are rare, with little known about their natural history and growth rate or their optimal management. The specific objectives of this study were to (1) define the clinical features of RAAs, including the precise growth rate and risk of rupture, (2) examine the current management and outcomes of RAA treatment using existing guidelines, and (3) examine the appropriateness of current criteria for repair of asymptomatic RAAs. METHODS A standardized, multi-institutional approach was used to evaluate patients with RAAs at institutions from all regions of the United States. Patient demographics, aneurysm characteristics, aneurysm imaging, conservative and operative management, postoperative complications, and follow-up data were collected. RESULTS A total of 865 RAAs in 760 patients were identified at 16 institutions. Of these, 75% were asymptomatic; symptomatic patients had difficult-to-control hypertension (10%), flank pain (6%), hematuria (4%), and abdominal pain (2%). The RAAs had a mean maximum diameter of 1.5 ± 0.1 cm. Most were unilateral (96%), on the right side (61%), saccular (87%), and calcified (56%). Elective repair was performed in 213 patients with 241 RAAs, usually for symptoms or size >2 cm; the remaining 547 patients with 624 RAAs were observed. Major operative complications occurred in 10%, including multisystem organ failure, myocardial infarction, and renal failure requiring dialysis. RAA repair for difficult-to-control hypertension cured 32% of patients and improved it in 26%. Three patients had ruptured RAA; all were transferred from other hospitals and underwent emergency repair, with no deaths. Conservatively treated patients were monitored for a mean of 49 months, with no acute complications. Aneurysm growth rate was 0.086 cm/y, with no difference between calcified and noncalcified aneurysms. CONCLUSIONS This large, contemporary, multi-institutional study demonstrated that asymptomatic RAAs rarely rupture (even when >2 cm), growth rate is 0.086 ± 0.08 cm/y, and calcification does not protect against enlargement. RAA open repair is associated with significant minor morbidity, but rarely a major morbidity or mortality. Aneurysm repair cured or improved hypertension in >50% of patients whose RAA was identified during the workup for difficult-to-control hypertension.