Malpractice Allegations Against Vascular Surgeons:Prevalence, Risk Factors, and Impact on Surgeon Wellness

OBJECTIVES

The contemporary medicolegal environment has been linked to procedure overuse, healthcare variation, and higher costs. For physicians accused of malpractice, there is also a personal toll. The objective of this study was to evaluate the prevalence of and risk factors for involvement in medical malpractice lawsuits among US vascular surgeons, and to examine the association between these allegations with surgeon wellness.

METHODS

In 2018, the Society of Vascular Surgery (SVS) Wellness Task Force conducted a confidential survey of active members using a validated burnout assessment (Maslach Burnout Index) embedded into a questionnaire. This survey included questions related to medical errors and malpractice litigation. De-identified demographic, personal, and practice-related characteristics were assessed in respondents who reported malpractice allegations in the preceding two years, then compared to those without recent medicolegal litigation. Risk factors for malpractice allegations were identified (chi-square, Kruskal-Wallis tests), and the association between malpractice allegations with wellness was examined. Multivariate logistic regression models were developed to identify independent risk factors for malpractice accusations.

RESULTS

Of 2905 active SVS members, 871 responses from practicing vascular surgeons were analyzed. 161 (18.5%) were named in a malpractice lawsuit within two years. Malpractice allegations were significantly associated with surgeon burnout [OR 1.47 (1.01, 2.15), p=0.041], but not with self-reported depression or suicidal ideation. The nature of malpractice claims included procedural errors (23.1%), failure to treat (18.8%) and error/delay in diagnosis (16.9%). 20% of claims were settled prior to trial and 19% were dismissed. Defendant vascular surgeons reported a "fair" resolution in 26.4% of closed cases. By unadjusted analysis, factors significantly associated with recent malpractice claims included mean age (51.7+/-10.0 vs. 49.3+/-11.2; p=0.0044) and mean years in practice (18.0+/-10.7 vs. 15.2+/-11.8; p=0.0007). Multivariate analysis revealed independent variables associated with malpractice allegations, including on-call frequency (p=0.0178), recent medical errors (p=0.0189), and male surgeons (p=0.045).

CONCLUSIONS

Malpractice allegations are common for vascular surgeons and are significantly associated with surgeon burnout. Nearly 20% of survey respondents reported being named in a lawsuit within the preceding two years. Our findings underscore the need for SVS initiatives to provide counseling and peer support for vascular surgeons facing litigation.

Upper extremity trauma: current trends in management

Upper extremity trauma can be penetrating or blunt in etiology. The close proximity of vein, artery and nerve makes for a complicated presentation and potentially complicated reconstruction. Orthopedic and neurologic injuries can cause the more long term disability of these patients, but vascular injuries are initially more life threatening. Control of vascular injuries can be particularly difficult due to anatomic issues in the upper extremities. The intervention carried significant morbidity until evolution to endovascular approaches occurred. By reconstructing the injury from a more ''remote'' access site, less concomitant injury to the extremity can be encountered. However, although control of vascular injuries may result in greater survival rates with less morbidity from the procedure, long term outcome remains dependent upon concomitant injuries. This review will encompass both vascular and neurologic injuries secondary to trauma to the upper extremity and outline some of the trends in management.

Brave new world: the role for endovascular aneurysm repair in contemporary vascular surgery

Endovascular abdominal aortic aneurysm repair (EVAR) poses certain challenges to the vascular surgeon. Based upon our 6-year experience, we have highlighted important aspects of patient selection. EVAR can be performed in patients with significant co-morbidities, but technical success may be limited by anatomic criteria. Short to mid-term outcomes report low mortality and morbidity from EVAR. Acute and delayed conversion, rupture, endoleak, limb occlusion, and migration are complications occurring in EVAR; their frequency, presentation and management are described. EVAR has up to 90% success rate at several years follow-up including the use of secondary procedures. Secondary procedures are not infrequent after EVAR; thus close follow-up is of the utmost importance. We predict that EVAR will continue to be a valuable tool in the future.

Prevention and management of ureteral injuries during aortic surgery

Ureteral injury during aortic surgery may lead to life-threatening consequences. Unlike gynecologic or abdominal surgical procedures in which ureteral injuries more commonly occur, this type of iatrogenic injury may be particularly hazardous because of the presence of prosthetic graft material. Ureteral obstruction by extrinsic compression, from an anteriorly placed graft limb or retroperitoneal fibrosis, is the most commonly reported type of ureteral complication. In most vascular surgical series, direct ureteral injury occurs in less than 1% of cases, and ureteral obstruction occurs from 2% to 14% of aortoiliac reconstructions. Prevention of ureteral injury begins with an intimate knowledge of the anatomy of the ureter along its entire course from the abdomen to the pelvis, and a realization of possible anomalies. Recognition of an injury is the next key to a successful outcome. Intraoperative recognition of an injury may allow immediate repair with a high rate of success. There are many options for the management of ureteral injuries depending on the nature of the injury, the time of diagnosis, and the level of the ureter at which the injury has occurred. The authors review the anatomy and most common causes of ureteral injury during aortic surgery and provide a guide to appropriate surgical management of these injuries.

Influence of NASCET/ACAS trial eligibility on outcome after carotid endarterectomy

PURPOSE

Proponents of carotid angioplasty and stenting suggest that "high risk" patients, defined as patients excluded from the North American Symptomatic Carotid Endarterectomy Trial (NASCET) and Asymptomatic Carotid Atherosclerosis Study (ACAS), may have a significantly higher risk of stroke with carotid endarterectomy (CEA). However, this selected patient cohort has been poorly studied.

METHODS

A retrospective review of patients who underwent CEA during a 2-year period at a tertiary referral institution was performed. Each patient was evaluated and categorized, according to the exclusion criteria, by NASCET and ACAS standards. Statistical analysis using chi(2) and Fisher exact tests was performed.

RESULTS

There were 366 CEAs performed on 348 patients, including 32 (8.7%) for recurrent stenosis. A subgroup of 169 (46.2%) patients were trial ineligible. Focal ipsilateral symptoms were present in 148 (40.4%) of the patients. There were 9 (2.5%) strokes and 1 (0.3%) death, secondary to a major stroke, for an overall stroke and death rate of 2.5%. Trial-eligible patients had a stroke/death rate of 1.5% (3/197) while trial-ineligible patients had a 3.6% (6/169) stroke/death rate (P = .17).

CONCLUSION

Patients who were considered high risk for CEA as defined by trial ineligibility were common, comprising approximately half of our patients. Although trial-ineligible patients had a nonsignificant trend toward higher neurologic morbidity when compared with the eligible group, the risks were still comparable with NASCET/ACAS results. CEA was a safe procedure even in this "high risk" group. As such, ineligibility for a randomized carotid intervention trial should not be employed as a "de novo" indication for carotid stenting.

Development of oral heparin therapy for prophylaxis and treatment of deep venous thrombosis

OBJECTIVE

To review the current research and published literature regarding the development of oral heparin therapy for the prophylaxis and treatment of deep venous thrombosis.

BACKGROUND

Currently, the accepted practice of prophylaxis and/or treatment of acute deep venous thrombosis (DVT) is intravenous or subcutaneous (SQ) heparin followed by oral warfarin or SC low molecular weight heparin (LMWH) therapy followed by warfarin. Both of which are less than ideal. More recently, advances have been made towards an effective oral heparin preparation that would resolve many of the drawbacks to the current therapies.

METHODS

A review of the current and relevant English literature identified via a search of the Medline database from January 1990 to present.

RESULTS

Initial oral heparin therapy for DVT was unsuccessful due to presumed inadequate intestinal absorption as a result of heparin's molecular and structural characteristics. The development of oral heparin therapy, based on combining heparin with the carrier molecule Sodium N-(8[2-hydroxybenzoyl]amino) caprylate (SNAC) to enhance its intestinal absorption and bioavailability for the prophylaxis and treatment of DVT has been demonstrated to be effective in animal models. More recent efforts have been aimed at human trials.

CONCLUSION

Recent advances in prophylaxis and treatment of DVT have stimulated great interest among researchers to develop an effective, convenient, and well tolerated oral therapy. An effective oral heparin therapy may represent an ideal method of prophylaxis and treatment of DVT.

External transabdominal manipulation of vessels: a useful adjunct with endovascular abdominal aortic aneurysm repair

During endovascular abdominal aortic aneurysm repair, a severely angulated aortic neck or tortuous iliac arteries can make delivery of endografts difficult. We describe a simple adjunct in which transabdominal manipulation of vessels is used, which can greatly facilitate delivery of these devices in patients with challenging anatomy.

Comparison of open transabdominal AAA repair with endovascular AAA repair in reduction of postoperative stress response

Operative intervention causes a necessary biologic response known as the hypermetabolic stress response. Less invasive operative procedures may cause fewer metabolic and endocrine derangements. To evaluate the metabolic and endocrine differences between endovascular and transperitoneal abdominal aortic aneurysm (AAA) repair, 10 patients underwent standard open repair (open group) and 10 patients underwent endovascular repair of AAA (endovascular group) with a modular bifurcated endograft. Blood samples were obtained prior to general anesthesia (baseline) and every 6 hr for a 24-hr period. Assays for hormones related to the postoperative stress response as well as retinol-binding protein were performed. Peak hormonal values are presented in relation to the baseline. Demographic analysis of the two groups showed that there were no significant differences in age or ASA classification. The open group had a 9.6-fold increase in epinephrine release, which was significantly higher than the 1.6-fold increase in the endovascular group (p < 0.05). Elevations in cortisol were also significantly higher in the open group. Early postoperative nutritional derangements, as reflected by the levels of retinol-binding protein, were far less in the endovascular group than in the open group. Endovascular AAA repair appears to be associated with a marked reduction in the hypermetabolic stress response and nutritional deterioration, compared to traditional open repair. This reduction in physiologic stress may have salutary effects on the incidence of postoperative medical morbidity.

Minimally invasive vascular techniques

The recent and continuing developments in radiotherapy, gene therapy, and the technologies of imaging, materials, and devices, as well as the techniques for their implementation, have expanded the options available for the treatment of peripheral vascular disease. Though long-term data are still lacking, percutaneous transluminal angioplasty (PTA) has developed into a treatment modality in its own right and continues to be an adjuvant treatment to traditional surgical revascularization. Numerous stents and grafts are currently available for the treatment of arterial lesions and aneurysms, while the testing of many more continues. In addition to these new devices, developments in gene therapy and brachytherapy have brought several new minimally invasive options to the treatment of peripheral vascular disease.

Orally administered unfractionated heparin with carrier agent is therapeutic for deep venous thrombosis

BACKGROUND

Orally administered heparin (OHEP) is unreliable because of poor absorption. Sodium N-(8[2-hydroxybenzoyl]amino) caprylate (SNAC) is an amido acid that facilitates the gastrointestinal absorption of heparin. We evaluated the effectiveness of OHEP combined with SNAC (OHEP/SNAC) in the treatment of deep-vein thrombosis (DVT).

METHODS AND RESULTS

An internal jugular DVT was produced in 54 male Sprague-Dawley rats. Animals were assigned to 6 different groups for 7 days of treatment: untreated control, subcutaneous heparin (SC HEP) (300 U/kg SC TID), SNAC only (300 mg/kg PO TID), OHEP only (30 mg/kg PO TID), low-molecular-weight heparin (LMWH) (enoxaparin 5 mg/kg SC QD), and OHEP/SNAC (30 mg/kg:300 mg/kg PO TID). The activated partial thromboplastin time (aPTT) and anti-factor X (anti-Xa) levels were measured. The incidence of residual DVT after 1 week of treatment was 100% (9 of 9) in the control group versus 10% (1 of 10) in the OHEP/SNAC and 10% (1 of 10) in the LMWH groups (P<0.001). There was also a significant reduction in clot weights between these groups. Compared with controls, there were no significant differences in the residual DVT in the SNAC-only (6 of 6), OHEP-only (9 of 9), or SC HEP (8 of 10) groups. Combination OHEP/SNAC was as effective in the resolution of the clot and reducing clot weight as LMWH. The aPTT levels in the OHEP/SNAC group peaked at 30 minutes and were significantly higher than in all other groups (P<0.01). Anti-Xa levels were elevated at 15 minutes after dosing in the OHEP/SNAC group and remained significantly elevated at 4 hours (P<0.001).

CONCLUSIONS

OHEP combined with a novel carrier agent (SNAC) successfully treated DVT in this rat model.

Treatment of experimentally induced caval thrombosis with oral low molecular weight heparin and delivery agent in a porcine model of deep venous thrombosis

OBJECTIVE

This experiment evaluated enterally administered low molecular weight heparin (LMWH) combined with sodium N-[10-(2-hydroxybenzoyl)amino] decanoate (SNAD) for the treatment of induced venous thrombosis.

SUMMARY BACKGROUND DATA

SNAD is a delivery agent that potentiates the gastrointestinal absorption of LMWH.

METHODS

Forty female pigs were equally assigned to four groups: control (saline); enteral LMWH, 2,000 IU/kg; enteral SNAD, 50 mg/kg; and enteral LMWH, 2,000 IU/kg and SNAD, 50 mg/kg. Under fluoroscopic guidance, the infrarenal vena cava was occluded with a balloon catheter. Two milliliters of ethanol was injected into the distal vena cava. The inflated balloon catheter remained in situ for 5 days, at which time animals angiographically exhibiting thrombus were randomly assigned to the four groups. Study medications were dosed at 12-hour intervals by means of a gastrostomy tube placed previously. After 7 days of treatment, thrombus was extracted. A separate group of 10 animals was used to measure plasma antifactor Xa levels for 6 hours after enteral dosing of LMWH/SNAD.

RESULTS

The amount of residual thrombus after treatment with enteral LMWH/SNAD was significantly decreased. Antifactor Xa levels were significantly elevated in the LMWH/SNAD group versus baseline.

CONCLUSION

The combination of enterally administered LMWH and SNAD given for 7 days appeared to decrease caval thrombosis in this model of deep vein thrombosis. Enteral LMWH/SNAD effected an increase in plasma levels of antifactor Xa.

Endovascular treatment of multiple visceral artery paradoxical emboli with mechanical and pharmacological thrombolysis

PURPOSE

To report a case of paradoxical emboli to multiple visceral vessels treated with both mechanical (AngioJet device) and pharmacological (urokinase) thrombolysis.

METHODS AND RESULTS

A 72-year-old man presented with a 48-hour history of symptomatic right renal ischemia, which was treated with heparinization. Five days later, an abrupt creatinine elevation prompted arteriography, which demonstrated thromboembolism of the superior mesenteric artery (SMA) and both renal arteries. The AngioJet aspiration device was employed to successfully remove the clot from the SMA; urokinase infusion restored flow to the left kidney. At the 16-month follow-up evaluation, the patient was normotensive without medication and had a stable creatinine (1.4 mg/dL).

CONCLUSIONS

Because of its speed and minimal morbidity, the AngioJet device may be an attractive alternative to surgical embolectomy or pharmacological thrombolysis in highly selected cases of acute visceral artery thromboembolism.

Hospital cost of endovascular versus open repair of abdominal aortic aneurysms: a multicenter study

BACKGROUND

Technology-driven innovation in medicine is frequently associated with higher costs than conventional therapy. A significantly higher cost for endovascular ($21,250, n = 190) versus open abdominal aortic aneurysm (AAA) repair ($12,342, n = 60) was suggested by a direct cost analysis of patients in a multicenter trial. Estimated inpatient costs (not charges) incurred nationwide by hospitals for endovascular and open repair of AAA were studied to validate these observed trends.

METHODS

A retrospective analysis of 131 patients undergoing endovascular AAA repair was compared with 49 patients undergoing open repair as part of a Food and Drug Administration phase II prospective multicenter clinical investigation (AneuRx-Medtronic). A model to estimate costs was constructed using important clinical descriptors of these patients. These clinical characteristics where then matched with those from 22, 460 patients undergoing AAA repair obtained from a large national database (Medicare Provider Analysis and Review). Estimated hospital cost was then assigned to each study patient according to the national average of the total hospital costs for the respective matched patients in Medicare Provider Analysis and Review.

RESULTS

Total inpatient hospital costs of endovascular repair were significantly higher than that of open repair ($19,985 +/- 7396 versus $12,546 +/- 5944, respectively, P =.0001). Endograft device cost ($10,400) accounted for 52% of the total cost of endovascular repair. The 1999 mean blended Medicare reimbursement for AAA repair was $18,989.

CONCLUSION

In this early development stage, hospital cost for endovascular AAA repair is significantly greater than open repair when device cost greatly exceeds $5000. Although incremental reductions in cost of endovascular repair may be anticipated if use of diagnostic studies, operating time, and length of stay decrease, device cost has the single greatest impact on the expense of endovascular AAA repair. At current device pricing, mean blended Medicare reimbursement does not cover the cost of endovascular AAA repair.

Endovascular repair of abdominal aortic aneurysms

Endovascular treatment of abdominal aortic aneurysms (AAAs) is an exciting new minimally invasive treatment option for patients with this disease. Ochsner Clinic has been the only institution in the Gulf South participating in FDA clinical trials of these investigational devices. Early results with endovascular AAA repair demonstrate a trend towards lower mortality and morbidity when compared with traditional open surgery. Length of stay has been reduced by two-thirds with a marked reduction in postoperative pain and at-home convalescence. If the long-term data on efficacy and durability of these devices are good, most AAAs in the future will be treated with this minimally invasive technique.

Oral low-molecular weight heparin and delivery agent prevents jugular venous thrombosis in the rat

PURPOSE

Sodium N-[10-(2-hydroxybenzoyl)amino]decanoate (SNAD) is a novel carrier that allows the gastrointestinal absorption of low-molecular weight heparin (LMWH). The purpose of this experiment was to evaluate oral LMWH with SNAD for the prevention of deep venous thrombosis.

METHODS

Sixty Sprague-Dawley rats were equally assigned to five experimental groups: group 1 (control), oral saline solution; group 2, oral LMWH (15 mg/kg); group 3, oral SNAD (300 mg/kg); group 4, subcutaneous LMWH (5 mg/kg); and group 5, oral LMWH (15 mg/kg) and SNAD (300 mg/kg). After treatment, the jugular vein was isolated, occluded, and bathed in an ethanol and formalin solution for 2 minutes. Two hours later, the vessel was examined for patency, presence of thrombus, and thrombus weight. Serum measurement of anti-factor Xa activity was performed in a separate set of 30 rats, which were placed into the following four groups: group A, LMWH (5 mg/kg); group B, oral LMWH (15 mg/kg) and SNAD (300 mg/kg); group C, oral LMWH (15 mg/kg); and group D, SNAD (300 mg/kg).

RESULTS

The animals that underwent oral LMWH/SNAD therapy had a statistically significant decrease in visible thrombi. The thrombus weight of the oral LMWH/SNAD group was significantly less than the weights of all other groups, except the subcutaneous LMWH group. Anti-factor Xa levels were significantly elevated in the LMWH/SNAD group. There was no statistically significant difference between the data for the oral LMWH/SNAD group and the subcutaneous LMWH group.

CONCLUSION

The combination of oral LMWH and SNAD prevented deep venous thrombosis. The oral LMWH and SNAD therapy effected an increase in levels of anti-factor Xa.

Complications associated with percutaneous closure devices

BACKGROUND

In an effort to reduce time to hemostasis after angiography, several closure devices have been marketed. We report some of their complications.

METHODS

A retrospective review was conducted.

RESULTS

Over an 8-month study period, 2,181 diagnostic and interventional procedures were performed. Closure devices were used in 408 (19%) of these patients. The Angio-Seal closure device is composed of a collagen sponge and an absorbable polymer anchor that compresses the hole in the arteriotomy. The ProstarXL sealing device consists of a rotating barrel that deploys 4 needles through the arteriotomy, and then individual knots are extracorporeally tied. The Duett device consists of a balloon occluding catheter and injectable collagen and thrombin. Ten of the patients developed a complication from the closure device (2.5%). Four of these were subcutaneous abscesses. Two of these patients had expanding pseudaneurysms, 2 had lower extremity ischemia, and 1 patient had an acute bleed. These complications were all managed surgically. Another patient developed a retroperitoneal bleed that was managed nonoperatively.

CONCLUSIONS

As the use of these devices increase, these complications will become more common.

Carotid endarterectomy in patients with significant renal dysfunction

PURPOSE

Recent reports suggest that carotid endarterectomy (CEA) should not be performed in patients with end-stage renal disease (ESRD) because of an unacceptable rate of perioperative stroke and other morbidity. Because these conclusions were based on a small number of patients, we reviewed the perioperative and long-term outcome of patients with ESRD and chronic renal insufficiency (CRI) who underwent CEA at our institution.

METHODS

The 1081 patients who had a CEA between 1990 and 1997 were cross-referenced with those patients in whom renal insufficiency had been diagnosed. These charts were reviewed for patient demographics and perioperative and long-term outcome. Patients undergoing CEA during a 1-year period (1993) served as controls.

RESULTS

Fifty-one CEAs were performed in 44 patients with CRI (32 in 27 patients) and ESRD (19 in 17 patients). In the CRI+ESRD group, 66.7% were symptomatic, and 70.7% of the control group were symptomatic. Six operations (11.8%) in the CRI+ESRD group were redo endarterectomies. There were no perioperative strokes in the CRI+ESRD group, but one patient died 29 days postoperatively because of a myocardial infarction, for a combined stroke-mortality rate of 2.0%. The control group had a 2.6% combined stroke-mortality rate. Long-term survival analysis revealed a 4-year survival rate of 12% for patients with ESRD and 54% for patients with CRI, compared with 72% for controls (P <.05).

CONCLUSION

CEA can be performed safely in patients with ESRD or CRI, with perioperative stroke and death rates equivalent to that of patients without renal dysfunction. However, the benefit of long-term stroke prevention in the asymptomatic patient with ESRD is in question because of the high 4-year mortality rate of this patient population.

Abdominal and thoracoabdominal aortic aneurysm

Most abdominal aortic aneurysms (AAA) and thoracoabdominal aortic aneurysms (TAAA) are asymptomatic and are found on physical exam or incidentally during radiological studies for other indications. These aneurysms are repaired primarily because their risk of rupture increases geometrically as the size exceeds 5 cm. The potential morbidity of intraoperative visceral and spinal ischemia involved with TAAA repair may be reduced with various adjunctive maneuvers.

Orally administered heparin for preventing deep venous thrombosis

BACKGROUND

Sodium N-(8-[2-hydroxybenzoyl] amino) caprylate (SNAC) is an acetylated amino acid molecule that facilitates the gastrointestinal absorption of heparin. This study was undertaken to evaluate the efficacy of orally administered combination SNAC:heparin in preventing deep venous thrombosis in a standard rat model.

METHODS

Forty-four adult male Sprague-Dawley rats were randomly divided into five groups: group I control, group II SNAC, group III oral heparin, group IV combination SNAC:heparin, and group V intravenous heparin. Thirty minutes after drug administration, the internal jugular vein was bathed in a sclerosant mixture for 2 minutes and reexplored at 120 minutes. Activated partial thromboplastin times (aPTT) were measured in 30 rats equally divided into three groups: group I SNAC, group II oral heparin, and group III combination SNAC:heparin. Forty-five minutes posttreatment, blood was obtained for aPTT levels.

RESULTS

The incidence of deep venous thrombosis in the control group was 89% (8 of 9) versus 25% (2 of 8) in the combination SNAC:heparin group (p < 0.01). There was also a significant reduction in clot weight among groups. Combination SNAC:heparin significantly increased aPTT levels compared with SNAC or oral heparin alone.

CONCLUSION

In a rat model of venous thrombosis, combination of orally administered heparin:SNAC elevated aPTT levels and significantly reduced the formation of deep venous thrombosis.

Effect of cilostazol on walking distances in patients with intermittent claudication caused by peripheral vascular disease

PURPOSE

This study evaluated the effects of cilostazol on walking distances in patients with intermittent claudication (IC) caused by peripheral arterial occlusive disease.

METHODS

The study was a multicenter, randomized, double-blind, placebo-controlled trial. Two hundred thirty-nine patients with IC were randomly assigned to receive cilostazol (100 mg b.i.d.) or a placebo for 16 weeks. All patients underwent serial, variable-grade, constant-speed treadmill testing. Absolute claudication distance (ACD), assessed at the end of the 12-hour dosing interval (trough), was the primary end point. Secondary end points included ACD assessed 3 to 4 hours after dosing (peak) and initial claudication distances (trough and peak). Functional status measures, including the Medical Outcomes Scale (SF-36) and Walking Impairment Questionnaire, were used to assess subjective changes over the 16-week treatment period. Ankle-brachial indexes were calculated from Doppler-measured systolic pressures at every visit with treadmill testing.

RESULTS

Patients treated with cilostazol demonstrated significant improvements over the placebo patients in ACD at all three time points tested after baseline (weeks 8, 12, and 16). Peak treadmill testing at weeks 8 and 12 also showed significant improvement in walking distances for cilostazol-treated patients over placebo-treated patients. At week 16, patients in the cilostazol group had a 96.4-meter (47%) increase in ACD compared with 31.4 meters (12.9%) for the placebo group (p < 0.001). In the SF-36, significant improvement was observed in the physical component subscale and the composite physical component score. In the Walking Impairment Questionnaire, improvements were significant in patient reports of walking speed and specific measures of walking difficulty. Ankle-brachial indexes improved in the cilostazol group (0.64 +/- 0.02 to 0.70 +/- 0.02) compared with the placebo group (0.68 +/- 0.02 to 0.69 +/- 0.02) (p < 0.0125). The most frequent adverse events were headache, abnormal stools (e.g. loose stools), diarrhea, and dizziness.

CONCLUSIONS

Cilostazol significantly increased ACD at all measured time points and initial claudication distances at most time points. This agent may represent a new treatment option for patients with intermittent claudication.

Management of severe proximal vascular and neural injury of the upper extremity

PURPOSE

Early amputation has been suggested to be the optimal treatment for severe combined vascular and neural injuries of the proximal upper extremity. This retrospective study was done to evaluate the long-term clinical outcome of our policy of limb salvage by revascularization and delayed treatment of neural injuries.

METHODS

Forty-six patients with neural and vascular trauma to the upper extremity were treated at our institution. All of these patients had aggressive treatment directed at limb salvage with restoration of vascular supply and nerve function. Long-term vascular and neurologic outcomes were recorded. Neurologic deficits were validated by the American Medical Association's standardized disability impairment scale (0% to 100%).

RESULTS

The rate of preoperative disability was 83%, which improved to 52% (p < 0.01) after treatment (mean follow-up, 43 months). Overall, 87% showed improvement.

CONCLUSION

These results suggest that early amputation should not be performed unless there is massive tissue loss or an attempt at limb salvage might endanger life. Final outcomes cannot be predicted on the basis of initial clinical presentation. As a group, the majority of these patients improved with aggressive intervention.

Cost savings associated with the nonroutine use of carotid angiography

BACKGROUND

To evaluate the economic impact of performing carotid endarterectomy based only on a diagnosis of duplex scanning, we evaluated a cohort of patients treated at our institution during 1 calendar year.

METHODS

Ninety-seven patients were evaluated and divided into two groups: those with and without arteriogram prior to their operation. Duplex scan and arteriogram results were reviewed to determine their effect on the operative plan. Hospital charges and physician fees were assessed for each patient admission. Operative results, complications, and total charges were compared between the two groups.

RESULTS

There was one operative stroke in each group for a stroke rate of 2%. Angiographic complications included one stroke and one femoral artery thrombosis. Two arteriograms led to a change in the operative plan. The hospital charges for patients without an arteriogram was $10,292 verses $13,906 for patients with an arteriogram (P < 0.01). Physician charges for patients without an arteriogram were $3,882, with angiograms and $6,297. The total charges related to the endarterectomy were $14,174 and $20,203, respectively. Arteriograms accounted for an increase of 43% in total charges.

CONCLUSION

Nonroutine use of angiography does not increase operative risk or postoperative length of stay, and preoperative angiography increases total charges by 43% ($6,029) per patient.

Endovascular treatment of abdominal aortic aneurysms: case report and review of literature

A case of endovascular treatment of abdominal aortic aneurysm is discussed along with a review of the literature. This recently introduced Food and Drug Administration Phase II treatment modality may have a significant impact on the approach to the treatment of aneurysmal disease. This discussion details the treatment of one typical patient and reviews the current status of endovascular therapy as it applies to infrarenal abdominal aortic aneurysms.

Implications for the vascular surgeon with prolonged (3 to 89 days) intraaortic balloon pump counterpulsation

PURPOSE

The intraaortic balloon pump (IABP) is useful in the treatment of failing hearts. Although most experience with IABPs has been with acute short-term use, the safe duration of therapy and possible complications of long-term IABP use are uncertain. We evaluated the feasibility, management, and complications associated with long-term IABP therapy.

METHODS

Fifty consecutive patients with 87 IABPs were evaluated retrospectively. All patients had IABP support for greater than 72 hours. Results and complications were evaluated.

RESULTS

The mean duration of IABP support was 23.2 days. There were 21 IABP-related complications in 16 patients: (16 ischemic, three infections, two hemorrhage). The rate of complications was 0.13 per patient-week of support. Significant predictors of complications were total days of IABP support (p < 0.0001), use of multiple IABPs (p < 0.0001), and attempted but unsuccessful percutaneous insertions (p < 0.001). Complications led to 14 vascular procedures (five patch angioplasties, four bypass procedures, two major amputations, one fasciotomy, one groin exploration for hemorrhage, and one removal of an infected Dacron patch). Percutaneous removals had a 14% complication rate compared with none after operative removal (p = 0.02). Thirty-two patients survived (64%). Of the survivors, 27 underwent transplant.

CONCLUSIONS

Prolonged IABP therapy is feasible and is associated with an acceptable rate of complications. Operative removal is superior to percutaneous removal. Percutaneous removal should be limited to short-term therapy. There is no need for mandatory removal or site rotation based solely on indwelling time.

The incidence, morbidity, and mortality of surgical procedures after orthotopic heart transplantation

OBJECTIVE

The authors present their experience with patients having undergone orthotopic heart transplantation (OHT) in whom surgical conditions subsequently developed that required operative intervention. The incidence, morbidity, and mortality of these procedures are reported.

SUMMARY BACKGROUND DATA

Several studies have evaluated the management options of biliary tract disease after OHT. Multiple reports of patients having undergone OHT who subsequently underwent peripheral vascular reconstructions, plastic reconstructive, and thoracic procedures also have been published.

METHODS

A chart review of 349 patients who underwent OHT between 1985 and 1996 was conducted to identify surgical procedures that were required in the post-transplant period. Their outcomes are reported.

RESULTS

Of 349 patients who underwent OHT, conditions requiring 94 surgical procedures developed in 54 patients (15%). Biliary tract disease developed in 17 patients (5%) who required cholecystectomy, 2 of the 5 patients with acute cholecystitis died. Eight patients (2%) underwent orthopedic procedures with no operative mortality. Flap advancements for sternal wound infections were performed in five patients and four deaths occurred. Seventeen thoracic procedures were performed in 11 patients with an overall mortality of 45%. Twenty-one vascular procedures were performed on 17 patients with 1 delayed death due to a malignancy. Seven patients underwent procedures of the colon and rectum with no mortality. Seven patients underwent repair of inguinal or incisional hernias with no mortality. Various infections occurred with one resultant death after operative intervention. Six procedures were performed for diseases of the small intestine with no resultant mortalities.

CONCLUSIONS

Patients having undergone OHT and chronic immunosuppression are at increased risk of having complications develop from infection. Acute cholecystitis and sternal wound infection caused an inordinate risk of complications and death. Malignancies developed in four patients who required surgical intervention. A heightened awareness of coexisting peripheral vascular disease in patients transplanted for ischemic cardiomyopathy should exist. Close screening before surgery and surveillance after surgery to identify risk factors for infection and vascular disease and to screen for malignancies are essential.

Sites of recurrence and long-term results of redo surgery

OBJECTIVE

The authors determined whether carotid endarterectomy in patients with recurrent stenosis could provide durable stroke prevention with acceptable perioperative risk.

SUMMARY BACKGROUND DATA

Balloon angioplasty and stenting are being advocated for recurrent stenosis because of the presumption that reoperation is unsafe with poor results.

METHODS

The authors retrospectively reviewed their experience with 67 patients undergoing 74 operations for recurrent stenosis in a recent 11-year period. This represented 8.4% of 883 endarterectomies performed during the same period.

RESULTS

At original operation, 55% had primary closure and 45% were patched. Reoperation was performed for amaurosis fugax and transient ischemic attack (45%), post-stroke (7%), global ischemia (10%), and asymptomatic severe occlusive disease (35%). Four patients (6%) undergoing simultaneous cardiac procedures were excluded from further analysis. Mean duration between primary and first redo operation was 78 months (range, 1-240 months). The 30-day combined mortality and stroke morbidity was 2.8%, evenly divided with 1.4% stroke and 1.4% mortality rates. Recurrent disease occurred predominantly (69%) in the previous endarterectomy site. Follow-up ranged from 1 to 162 months (mean, 48.2). Seventeen deaths occurred, of which 10 (59%) were cardiac. Two late ipsilateral neurologic events and four late contralateral events occurred. Two patients required third ipsilateral reoperation. Life-table analysis shows the ipsilateral stroke-free rate at 5 years to be 93.6%

CONCLUSIONS

Recurrent stenosis occurs either proximal to or in the previous endarterectomy site in the majority of patients. Recurrent stenosis can be treated surgically with low morbidity and mortality and durable long-term stroke prevention. The presumption that results of redo carotid surgery are poor is disproved.

Comparison of surgical bypass and percutaneous balloon dilatation with primary stent placement in the treatment of central venous obstruction in the dialysis patient: one-year follow-up

Central venous stenosis and occlusion are complications that are being observed with increasing frequency as a result of the use of long-term central venous catheters. These complications are especially problematic in patients with end-stage renal disease and functioning ipsilateral arteriovenous (AV) grafts or fistulas (AV grafts). We have previously demonstrated that the 1-year patency rate for simple balloon angioplasty in these patients is less than 10%. To compare the results of surgical treatment vs. percutaneous dilatation with stent placement, we undertook this retrospective study. All patients underwent multiple central venous catheter placements and had functioning ipsilateral AV grafts. Twenty-six patients were divided into two groups. The surgical treatment group included 13 patients: 10 with subclavian vein thrombosis and three with innominate vein thrombosis. All patients in the surgical group had arm swelling and edema. Surgical bypass procedures were performed in these patients using either polytetrafluoroethylene or saphenous vein. The stent group also included 13 patients; all of them had a diagnosis of subclavian or innominate vein obstruction and were treated with percutaneous transluminal angioplasty and placement of either a self-expanding rigid stent (n = 6) or a balloon-expandable flexible stent (n = 7). Two patients required multiple stent placements. No significant complications occurred in either group. The 1-year mortality rate in both groups was 31%. The percentages of patients who were symptom free at 6 and 12 months were also similar in the two groups. We conclude that surgical bypass and percutaneous transluminal angioplasty with stent placement are both efficacious in the treatment of central venous obstruction.

The effects of supraceliac aortic clamping on the anticoagulant effects of heparin

BACKGROUND

Coagulopathy is frequently encountered during supraceliac aortic clamping. Patients are routinely heparinized during these operations. This experiment was undertaken to evaluate the effect of supraceliac aortic cross-clamping (XC) on heparin pharmacodynamics.

MATERIAL AND METHODS

Fourteen mongrel dogs were randomly divided into three groups: Group 1 (X; n = 6), 90 minutes aortic XC; Group 2 (SH; n = 4), sham operation and heparin, 100 mg/kg intravenously; and Group 3 (XH; n = 4), heparin, 100 mg/kg intravenously 3 minutes before XC. Prothrombin time (PT) and partial prothrombin time (PTT) were measured serially. Heparin concentrations were estimated via automated titration with protamine sulfate.

RESULTS

After XC, PTT is increased during reperfusion. Heparin administration (XH) before aortic XC increases PTT above those with X or SH. Anticoagulation was potentiated and prolonged by XC. There was no difference in heparin concentration or PT.

CONCLUSION

Supraceliac aortic clamping significantly affects heparin pharmacodynamics and may contribute to coagulopathy.

Tissue factor pathway inhibitor protects the ischemic spinal cord

Tissue factor pathway inhibitor (TFPI) is a novel agent that binds to tissue factor/VIIa complex and factor-Xa, thereby reducing the effect of tissue factor (TF) on inflammation and the extrinsic pathway of coagulation. We hypothesize that systemic treatment with TFPI may limit ischemia-reperfusion (IR) injury. Our experiment was designed to evaluate the effects of TFPI on IR in the spinal cord. Twenty-three adult New Zealand white rabbits had snare occlusion devices placed circumferentially around the aorta and tunneled to a subcutaneous position. Forty-eight hours later, in the fully awake state, the animals were treated with either TFPI (1 mg/kg bolus followed by a 1-hr infusion of 20 microgram/kg/min), or heparin (100 U/kg bolus) followed by a 1-hr infusion of 10 ml/kg/hr of PBS while controls received phosphate buffered saline (20 ml followed by a 1-hr infusion of 10 ml/kg/hr). The infrarenal aorta was occluded for 21 min in all groups via the snare device. Animals were observed for 3 days and neurologic recovery was graded by the Tarlov criteria. Results were evaluated as percent of animals with hindlimb recovery (Tarlov 3 and 4). At 24 hr postocclusion, 88% of the TFPI-treated animals had recovered neurologic function versus only 20% of heparin-treated animals and 10% of the phosphate buffered saline group (P=0.031 and 0.009, respectively). At 72 hr, 63% of the TFPI animals retained neurologic function versus 20% of heparin-treated animals and 10% of phosphate buffered saline-treated animals (P=0.032, TFPI versus phosphate buffered saline). The mechanism of action of TFPI is not completely understood, yet this drug may hold promise in the prevention of IR injury of the spinal cord.

Ischemia-reperfusion injury of the spinal cord: the influence of normovolemic hemodilution and gradual reperfusion

Recent studies have suggested that oxygen-derived free radicals play an important role in ischemia-reperfusion injury of the spinal cord. In other organ systems, reperfusion injury has been reduced by limiting the availability of oxygen in the reperfusion phase. The purpose of this study was to test the effect of normovolemic hemodilution and gradual reperfusion on spinal cord function after aortic cross-clamping in 84 New Zealand White rabbits. All animals underwent 21 min of infrarenal aortic cross-clamping in the conscious state by means of a previously placed aortic occlusion device and were randomized to four groups. Group 1 animals were hemodiluted to a mean (s.e.m.) hematocrit of 28(2)% by extracting 25% of the effective blood volume and reinfusing the plasma component after centrifugation concurrently with a volume of normal saline three times that of the discarded red cells. Group 2 animals (controls) were bled similarly but both plasma and red cells were reinfused, resulting in a mean (s.e.m.) hematocrit of 38(2)%. In the next two groups, distal aortic flow was recorded via an implantable Doppler device. After cross-clamping, flow was returned gradually over 45 min in animals of group 3, and abruptly in group 4. Animals were observed for 5 days and neurologic function was graded by an independent observer. Paraplegia at 5 h after clamping occurred in 75% of animals in group 1 versus 32% in group 2 (P < 0.05), and in 33% of group 3 versus 28% in group 4 (not significant). Of those animals showing initial neurologic recovery, delayed-onset paraplegia was seen in 100% in group 1 versus 87% in group 4 (not significant), and in 50% of group 3 versus 92% of group 4 (P < 0.03).(ABSTRACT TRUNCATED AT 250 WORDS)

Ischemia-reperfusion injury of the spinal cord: protective effect of the hydroxyl radical scavenger dimethylthiourea

PURPOSE

This study was undertaken to evaluate whether neurologic outcome after aortic cross-clamping in rabbits could be improved with perioperative infusion of the hydroxyl radical scavenger dimethylthiourea and, if so, to determine whether it is effective during the period of ischemia, reperfusion, or both.

METHODS

In 41 New Zealand White rabbits, a snare occlusion device was placed at operation around the infrarenal aorta and tunneled into a subcutaneous position. Animals were then allowed to recover and, 48 hours later, randomized into four groups. In each group, the infrarenal aorta was occluded by tightening the snare in the awake animal. In groups 1, 2, and 3, cross-clamp time was 21 minutes. Group 1 (control) animals received saline solution, whereas group 2 (preclamp 21) received dimethylthiourea 750 mg/kg intravenously just before aortic clamping. In group 3 (prerep 21), dimethylthiourea was given just before reperfusion. Group 4 received dimethylthiourea before clamping, with cross-clamp time extended to 31 minutes. A second dose of saline solution or dimethylthiourea was given 12 hours after clamping in controls and the three treatment groups, respectively. Animals were observed for 5 days, and final neurologic recovery was graded by an independent observer. Animals were then killed, and their spinal cords were removed for histologic examination.

RESULTS

Complete paraplegia and marked histologic spinal cord injury at 5 days were seen in 91% (10/11) of group 1 (control) animals, whereas all animals in group 2 (preclamp 21) showed neurologic recovery (p < 0.0001). In group 3 (prerep 21), the final paraplegia rate was 50% (5 of 10), in group 4 (preclamp 31), 100% (10 of 10).

CONCLUSIONS

Our results suggest that hydroxyl radicals play an important role in ischemia-reperfusion injury of the spinal cord and that treatment with dimethylthiourea can prevent paraplegia after 21 minutes of aortic cross-clamping in rabbits.

Risk of respiratory failure after repair of thoracoabdominal aortic aneurysms

BACKGROUND

Multiple complications occur after repair of a thoracoabdominal aortic aneurysm, the most common of which is respiratory failure.

METHODS

One hundred consecutive thoracoabdominal aneurysm repairs were studied retrospectively using univariate, bivariate, and multiple logarithmic regression analyses to identify factors associated with respiratory failure.

RESULTS

The mean of days of intubation was 5.8 +/- 0.8 (mean +/- SEM), with a median of 2 days. Patients who developed respiratory failure (21%) had a 42% mortality compared with a 6% mortality in patients who did not develop respiratory failure (P < 0.001). Statistical analysis demonstrated a significant (P < 0.01) age difference between those with respiratory failure (71.9 +/- 1.6 years) and those without (65.5 +/- 1.3 years). Type II aneurysms occurred in 32% of patients, a 3.2-fold increase in relative risk compared with all other types of aneurysm. Seventy-nine percent of patients had a significant smoking history. Low forced vital capacity and forced expiratory volume were both significant variables in predicting respiratory failure, but neither chronic obstructive pulmonary disease nor emphysema was a predictive variable. Intraoperative blood transfusion (mean 10.5 +/- 0.8 units) was associated with respiratory failure (P = 0.05). Postoperative complications associated with respiratory failure were creatinine elevation and pneumonia.

CONCLUSION

We conclude that the independent variables affecting respiratory failure after thoracoabdominal aneurysm repair are age, type of aneurysm, excessive intraoperative blood transfusions, creatinine elevation, and postoperative pneumonia.

Protecting the ischemic spinal cord during aortic clamping: the influence of selective hypothermia and spinal cord perfusion pressure

PURPOSE

We verified the hypothesis that selective deep hypothermia of the spinal cord during double thoracic aortic clamping can prevent postoperative paraplegia in dogs.

METHODS

Normal saline solution was circulated from the cisterna magna through an extracorporeal perfusion system consisting of a reservoir, a pump, and a heat exchanger, back into the subarachnoid space at the level of the medullary cone at a rate of 25 ml/min, starting 30 minutes before clamping, and ending after removal of the clamps. The thoracic aorta was cross-clamped below the left subclavian artery and above the diaphragm for a period of 45 minutes. Cerebrospinal fluid, intracranial, and central venous pressure and aortic pressure proximal, between, and distal to the clamps were continuously recorded. In five dogs, temperature of the circulating normal saline solution at the inflow level was maintained at 2 degrees +/- 1.5 degrees C (group 1), in five controls at 37 degrees +/- 0.8 degrees C (group 2). Five dogs underwent continuous cerebrospinal fluid drainage starting before clamping until sacrifice (group 3). Dogs were observed for up to 4 days, and neurologic function was graded by an independent observer with the Tarlov scale. Animals were then killed, and their spinal cords were prepared for microscopic examination.

RESULTS

Hemodynamic parameters were not significantly different between groups. All dogs in groups 2 and 3 were paraplegic with histologic evidence of spinal cord infarction. All animals in group 1 were neurologically normal without microscopic evidence of infarction (p < 0.005).

CONCLUSIONS

Selective deep hypothermia of the spinal cord prevents paraplegia after 45 minutes of double aortic clamping in dogs. Cerebrospinal fluid drainage was not effective in preventing paraplegia in this model.

Direct replacement of mycotic thoracoabdominal aneurysms

Direct graft replacement with local debridement and prolonged administration of antibiotics was used in the treatment of six patients with mycotic thoracoabdominal aneurysms. The only early death occurred in a patient with systemic sepsis related to Staphylococcus aureus mycotic suprarenal aneurysm. Long-term survival of the remaining patients has been excellent: two patients died of unrelated causes at 5 and 6 years, respectively; one patient remains alive with known persistent infection at 5 years; and the remaining patients are alive with no evidence of infection at 1 1/2 and 10 years, respectively. Percutaneous aspiration of infected perigraft fluid with local instillation of antibiotics along with administration of intravenous antibiotics may provide palliation in selected patients with recurrent infections. In view of the magnitude of the problems associated with recurrent infection, life-time administration of antibiotics is recommended after in situ graft replacement of mycotic thoracoabdominal aneurysms.

Financial impact of thoracoabdominal aneurysm repair

We have reviewed our experience regarding hospital costs and reimbursement for 72 patients who underwent thoracoabdominal aneurysm repair. Preoperative risk factors, postoperative complications, length of stay, and source of reimbursement were recorded for all patients. Patients covered by Medicare resulted in a mean net institutional loss of $16,472 per patient, whereas a mean net profit of $17,847 per patient resulted from patients with commercial insurance. Factors associated with institutional financial loss were: age over 75 years, preoperative coronary disease, postoperative respiratory failure, and length of stay. By multivariate analysis, however, only length of stay was independently associated with institutional loss.

Comparison of operative reconstruction and percutaneous balloon dilatation for central venous obstruction

To evaluate the efficacy of venous reconstruction versus percutaneous transluminal angioplasty for the treatment of obstruction of the superior vena cava and its major tributaries, we retrospectively reviewed the clinical course of 27 patients, of whom 13 underwent operative reconstruction and 15 had angioplasty (1 had both). Three patients had obstruction of the superior vena cava, 8 had occlusion of the innominate veins, and 16 had obstruction of the subclavian or axillary veins. In both treatment groups, mean age, indications, etiology, and location of the lesion were comparable. No major surgical complications occurred; one patient who underwent angioplasty experienced stent migration to the pulmonary artery without sequelae. Primary symptomatic relief at 1 year was achieved in 88% in the surgical group versus 36% in the angioplasty group (p < 0.05 by Fisher's exact test) and at 2 years in 71% versus 0%, respectively (p < 0.01). One- and 2-year success rates with repeated angioplasty, however, were 86% and 66% (p > 0.9), respectively. We conclude that the long-term success rate of operative reconstruction exceeds that of single percutaneous transluminal angioplasty. However, with repeated angioplasty, success rates approach those of operative reconstruction.

Risk of spinal cord dysfunction in patients undergoing thoracoabdominal aortic replacement

The records of 150 consecutive patients undergoing thoracoabdominal aortic replacement from 1980 to 1991 were retrospectively reviewed. There were 89 men and 61 women; mean age was 67.8 years (range: 33 to 88 years). Since June 1989, a multimodality prospective perioperative protocol was used to reduce the risk of spinal cord dysfunction. Ischemia is minimized by complete intercostal reimplantation whenever possible, cerebrospinal fluid drainage, and maintenance of proximal hypertension during cross-clamping. Spinal cord metabolism is reduced by moderate hypothermia, high-dose barbiturates, and avoidance of hyperglycemia. Reperfusion injury is minimized by the use of mannitol, steroids, and calcium channel blockers. Ninety-seven percent of patients survived long enough for evaluation of their neurologic function. Spinal cord dysfunction was reduced from 6 of 108 (6%) in the preprotocol group to 0 of 42 in the protocol group (0%) (p less than 0.01). The overall 30-day operative mortality was not significantly different between the groups (9% versus 12%, p = NS). A multimodality protocol appears to be effective in reducing the risk of spinal cord injury during thoracoabdominal aortic replacement.

Protecting the ischemic spinal cord during aortic clamping. The influence of anesthetics and hypothermia

Infrarenal circumaortic occlusion devices were operatively placed in 74 New Zealand white rabbits. Two days after operation the animals were randomly assigned to one of seven treatment groups: I, control, n = 23; II, halothane, n = 8; III, thiopental, n = 12; IV, ketamine (30 mg/kg intravenously), n = 6; V, halothane+hypothermia, n = 8; VI, thiopental+hypothermia, n = 12; VII, ketamine+hypothermia, n = 5. In each group, the infrarenal aorta was occluded for 21 minutes. Final neurologic recovery after restitution of blood flow was graded as acute paraplegia, delayed paraplegia (neurologic deficit developing after initial recovery), or normal. Halothane alone was of no benefit. Hypothermia with any anesthetic was completely protective and reduced neurologic deficits to 0% compared with 91% in controls (p less than 0.05). Thiopental and ketamine treatment each reduced acute paraplegia to 17% (as compared with 61% in controls) and increased delayed paraplegia from 30% in controls to 75% and 50%, respectively (p less than 0.05 for thiopental, p = 0.10 for ketamine). The authors interpret the increase in delayed deficits and decrease in acute deficits as being the result of partial spinal cord protection. These findings document that this model of spinal cord ischemia is sufficiently sensitive to identify interventional treatments that protect the ischemic spinal cord.

The effects of short-term ethanol exposure on the canine jejunal handling of calcium and glucose

The effects of ethanol on simultaneous jejunal handling of calcium and glucose were studied in long-term canine jejunal Thirty-Vella loops. The loops were perfused intraluminally in a random sequence with physiologic buffer, buffer containing 3.5% ethanol, and buffer containing 7% ethanol. The addition of 3.5% or 7% ethanol to the buffer reduced the net absorption of glucose by 13% and 26%, respectively. The addition of 7% but not 3.5% ethanol significantly increased the net secretion of calcium (168% of basal). In contrast, luminal perfusion with ethanol did not significantly alter intestinal handling of water, sodium, or potassium. Serum calcium and glucose levels were similarly unaffected by the ethanol perfusion. Mean serum ethanol levels were all less than 10 mg/dl. We conclude that intraluminal ethanol has a significant effect on the jejunal handling of glucose and calcium, and this effect is not dependent on systemic intoxication.

Immunocytochemical localization of estrogen and progesterone receptors in human thyroid

The presence of steroid hormone receptors has previously been suggested in thyroid tissue by biochemical means. Our studies were designed to confirm these results and to localize the specific receptor-containing cell type using a novel immunocytochemical method. Monoclonal antibodies specific to estrogen receptors (ER) and progesterone receptors (PgR) were used to localize these steroid hormone receptors in the human thyroid gland. Frozen tissue sections from surgical specimens excised from 22 patients of both sexes with benign thyroid disease were studied. The sections were incubated with rat antiestrophilin and antiprogesterone receptor antibodies and were then exposed to rabbit anti-rat IgG and to rat peroxidase-antiperoxidase complex. The reaction product was visualized with diaminobenzidine tetrahydrochloride and hydrogen peroxide. Four specimens were positive for both ER and PgR, 16 were ER-positive and PgR-negative, and two were negative for both ER and PgR. Positive reactivity was limited to the follicular lining cell nuclei and varied from focal to diffuse. The immunohistochemical findings confirmed the presence of ER and PgR in the thyroid tissue and demonstrated for the first time that these receptors are present only in the nuclei of the lining cells of the thyroid follicle. The role of steroid hormone receptors in the thyroid in health and disease remains to be explained.

The role of serotonin in the canine secretory response to cholera toxin in vivo

This study was initiated to evaluate the role of serotonin in cholera toxin-induced jejunal secretion of water and electrolytes. Chronic Thiry-Vella loops, constructed in six dogs, were perfused with an isosmotic neutral perfusate containing [14C]polyethylene glycol as the recovery marker. Fluxes of water, sodium, chloride and potassium were calculated and immunoreactive serotonin levels were measured in blood and effluent perfusates. Intraluminal application of 20 micrograms of cholera toxin induced secretion; fluxes of water (basal, 32.3 +/- 11.1; 6 hr, -541 +/- 35 microliter/min), sodium (basal, 9.0 +/- 2.8; 6 hr, -78.3 +/- 5.6 microEq/min), chloride (basal, 3.8 +/- 1.5; 6 hr, -65.7 +/- 4.0 muEq/min) and potassium (basal, 0.10 +/- 0.08; 6 hr, -2.80 +/- 0.18 muEq/min) were all significantly different from basal. Serum electrolytes remained normal, except that potassium fell from 4.9 +/- 0.5 to 3.9 +/- 0.2 mEq/l. Although circulating serotonin levels did not change from base line (180.9 +/- 29.3 ng/ml), effluent concentrations increased significantly from 68.2 +/- 4.6 to 81.1 +/- 5.0 ng/ml (at 3 hr) and jejunal outputs increased from 136.6 +/- 10.2 to 205.1 +/- 10.1 ng/min (at 6 hr). In a separate set of experiments, verapamil was infused i.v. (12.5 micrograms/kg/min) during the 4th hr in four dogs exposed to cholera toxin. The lower dose of toxin (5 micrograms) induced secretion which was unaffected by the calcium channel blocker. In another series of studies, ketanserin (a 5-HT2 receptor blocker) was infused i.v. at 33 micrograms/kg/min during the 4th hr in four additional dogs exposed to the lower dose of cholera toxin. This potent serotonin antagonist failed to inhibit cholera toxin-induced jejunal secretion.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute hypocalcemic effect of ethanol in dogs

Ethanol has been shown to reduce serum calcium in multiple animal studies. However, in human studies done using lower doses of alcohol, only inconclusive results have been obtained. This study was undertaken to evaluate the effects of varying doses of oral ethanol on total serum calcium. Fifteen adult mongrel dogs (17-25 kg) were divided into three groups which differed in the dosage of ethanol given. Group I animals received 0.5 g/kg of ethanol; Group II, 1.0 g/kg ethanol; and Group III, 2.0 g/kg of ethanol. Venous blood was sampled for estimation of concentrations of total serum calcium and ethanol. In the animals in Group I, serum calcium levels were unchanged by the ethanol. In both Groups II and III, significant reductions in serum calcium were demonstrated, which occurred within 5 min of intoxication. The mean decrease in serum calcium in Group III animals was significantly greater than that in either Group I and II. We conclude that the rapid hypocalcemic effect requires a threshold amount of ethanol before it becomes chemically evident. This critical value in dogs approximated 1 g/kg which results in a mean peak serum alcohol concentration of 117 +/- 6 mg/dl.

Segmental intestinal transplantation in rats with resected entire small bowel, ileocecal valve, and cecum

Segmental intestinal transplantation was studied in a rat model of severe short gut syndrome across major histoincompatibility barriers. Lewis (RT1l) recipient rats whose entire small bowel (approximately 80 cm), ileocecal valve, and cecum were resected and who had no transplant, uniformly died of malabsorption on Day 9.8 +/- 0.4 (n = 11). Without cyclosporine, allograft recipients (n = 2), died of rejection on Days 8 and 10. Recipient animals with 20-cm jejunum and 40-cm jejunal transplants from Buffalo (RT1b) rats and treated daily with cyclosporine (5 mg/kg/day) intramuscularly (Days 0-28) and vitamin B12 (every other week) enjoyed significantly prolonged survival to Day 58.2 +/- 13.7, P less than 0.003, n = 10, and Day 129.1 +/- 7.4, P less than 0.001, n = 10, respectively. While 7 of 10 rats in the 20-cm jejunal transplant group died of malabsorption between Days 14 and 58, none of 10 animals in the 40-cm jejunal transplant group died of this complication. Four of 10 rats in the 40-cm jejunal transplant group thrived at 150 days after the operation, at which time they were sacrificed. Morphologically, the grafts demonstrated hypertrophic changes. The data from this study suggest that intestinal allografts have pronounced intestinal adaptative characteristics. Using segmental jejunal grafts, intestinal transplantation is an effective surgical modality for the short gut syndrome in the rat.

Progesterone receptors in the human heart and great vessels

Progesterone receptors (PgR) were identified in 31 of 50 specimens of human (men and women) thoracic ascending aorta, internal carotid, coronary artery, and left atrial appendage. This was accomplished with a peroxidase-antiperoxidase immunocytochemical assay employing a highly specific monoclonal antibody to primate PgR. In the aorta, specific staining was seen in the nuclei of smooth muscle cells and endothelium of intima, media, and adventitia. In the myocardium, staining was localized to the nuclei of the myocardial fibers. In internal carotid and coronary arteries, PgR was localized to endothelial nuclei of intima, and in vascular channels within the atherosclerotic plaques. PgR was also visible in the smooth muscle cell nuclei of uninvolved media and intima and at the plaque periphery. In contrast, receptor was not identified in vessels of the human uterus, breast, prostate, kidney, or gastrointestinal tract. These findings suggest that the heart and great vessels are target organs for steroid hormones.

Effects of intravenous calcium on release of serotonin into jejunal lumen and portal circulation

The effect of intravenous calcium bolus (180 mg in 10 ml normal saline over 25-30 sec) on the release of serotonin into the jejunal lumen and the portal and peripheral venous circulation was studied. Proximal jejunal 25-cm cannulated Thiry-Vella loops were perfused with a neutral physiological buffer in an isoperistaltic direction at 2 ml/min. One minute after the calcium bolus, serum calcium levels increased from 8.7 +/- 0.3 to 14.2 +/- 0.8 mg/dl. Jejunal luminal concentrations of 5HT increased from 135 +/- 21 to 208 +/- 44 ng/ml at the same time; luminal levels peaked at 236 +/- 27 ng/ml at 7 min and slowly returned to baseline. In contrast, portal and systemic venous concentrations did not change after intravenous calcium bolus. The data support the contention that there are independent mechanisms for the release of serotonin into the bowel lumen and the blood stream.

The effects of cyclosporine on varying segments of small-bowel grafts in the rat

The relationship between the cyclosporine A (CSA) dose and rejection of varying lengths of small-bowel grafts was studied in a rat heterotopic microsurgical small-bowel transplantation model involving a haploidentical strain combination. When Lewis X Brown Norway F1 hybrid (LBN) small-bowel grafts were transplanted into Lewis (LEW) rats without CSA, all grafts in the proximal 10 cm, the proximal 40 cm, and the entire (approximately 80 cm) small bowel were rejected on days (mean +/- SEM) 6.6 +/- 0.2 (n = 11), 7.0 +/- 0.4 (n = 6), and 7.8 +/- 0.7 (n = 6), respectively. A 10-day course (days 0-9) of CSA 2 mg/kg significantly (p less than 0.05) prolonged the survival of the proximal 10 cm, the proximal 40 cm, and the entire small bowel allografts to days 18.8 +/- 1.7 (n = 5), 16.5 +2- 1.3 (n = 6), and 13.5 +/- 1.0 (n = 4), respectively. Similarly, the CSA 5 mg/kg regimen significantly (p less than 0.05) delayed the rejection of the 10 cm, the 40 cm, and the 80 cm small-bowel grafts to days 50.2 +/- 7.2 (n = 6), 47.7 +/- 2.6 (n = 3), and 40.3 +/- 5.8 (n = 3), respectively. However, 6 of 12 rats treated with CSA 5 mg/kg died of pneumonia, and these animals were all in groups with the 40 cm and 80 cm grafts. When these animals were included in calculations of rejection-free survival, the averages for the 40 and 80 cm groups treated with CSA 5 mg/kg were 34.2 +/- 6.4 and 28.7 +/- 6.1 days, respectively. CSA suppressed rejection of small-bowel allografts in a dose-related fashion. More important, significantly (p less than 0.05) lower doses of CSA were necessary for rats that received shorter intestinal grafts. In fact, the relationship between rejection and CSA dose in the 10 cm grafts was characterized by the formula: day of rejection = 9.3 [CSA dose]1.03. We conclude that the ideal small intestinal graft should be the smallest possible segment that maintains adequate nutrition and CSA doses should be matched for segment lengths.

Meal-stimulated release of methionine-enkephalin into the canine jejunal lumen

Application of enkephalins to the luminal surface of the bowel augments intestinal absorption. However, to date, endogenous enkephalins have not been demonstrated within intestinal luminal fluid. To determine whether enkephalins are present in the intestinal lumen, five adult dogs had 25-cm chronic jejunal Thiry-Vella loops constructed. Dogs were studied in the awake, fasted state. Jejunal loops were perfused with isoosmotic, neutral Krebs buffer containing protease inhibitors. After basal sampling, the dogs received a high fat meat meal. Collections were made during the meal and for 60 min postprandially. Luminal met-enkephalin levels were determined by radioimmunoassay and confirmed by HPLC. HPLC separation of luminal samples demonstrated two immunoreactive peaks which co-eluted with pure met-enkephalin and met-enkephalin-sulfoxide. Basal met-enkephalin outputs averaged 52 +/- 13 ng/min. The meal significantly increased mean luminal met-enkephalin output to 137 +/- 71 ng/min. During the initial 20-min postprandial period, output remained elevated (180 +/- 73 ng/min), after which it returned to basal levels. We conclude that met-enkephalin is present in the jejunal lumen, and that luminal release of this opioid is augmented by a meal.

The effects of size and site of origin of intestinal grafts on small-bowel transplantation in the rat

This study was initiated to evaluate the effects of varying the length and site of origin of small-intestine transplants on rejection and on graft-versus-host disease (GVHD). Eighty rats had heterotopic transplants performed with systemic venous drainage of the grafts. The host native bowel was left in situ and no immunosuppressive agents were used. Twenty male Lewis inbred (LEW) rats who received isogenic grafts survived without any evidence of rejection or GVHD. When intestine from Lewis X Brown Norway hybrid rats (LBN) was transplanted into LEW rats, rejection occurred between day 6 and 9 and the time of onset of rejection was not influenced either by the length of transplanted bowel (10 to 80 cm, n = 6 each) or by whether the graft was from the jejunum or the ileum. However, rates of survival for 100 days from rejection were significantly better if 10 cm (100%) or 20 cm (84%) was transplanted than if the grafts were 40 cm or more in length (56%). The LBN recipients of LEW allografts developed GVHD on days 7 through 9, and this response was similarly unrelated to the length or segment of bowel transplanted. However, host survival was quite dependent on graft segment length and site of origin. All animals who received 20 cm or less of proximal bowel survived (with GVHD but no evidence of rejection). While 50% of the animals that received proximal intestinal grafts 40 cm in length survived GVHD, none who received identical-sized grafts from the distal ileum survived (all were dead by day 20). Our data document that the results of small-intestine transplantation is dependent on the length and site of origin of the grafts.