William L. Smead

Complement depletion accelerates the clearance of immune complexes from the circulation of primates.

Binding of immune complexes (IC) to erythrocytes in vitro is the result of interaction between C3b sites on the IC, and complement receptors type I (CRI) expressed on primate erythrocytes. Recent evidence indicates that primate erythrocytes can also rapidly bind large, preformed IC in vivo. This study was undertaken to determine if the binding of IC to baboon erythrocytes in vivo is complement dependent and to examine the effect of complement depletion on IC clearance from the circulation. The results indicate that complement depletion in vivo reduced the binding of IC to erythrocytes. There was relatively little binding of IC to leukocytes in both the complement-depleted and complement-repleted condition. Thus, the majority of IC not bound to erythrocytes remained free in the plasma and, consequently, IC infusion during the complement-depleted state resulted in increased plasma IC concentrations. This was associated with a rapid disappearance of IC from the circulation. By contrast, in the normal or complement-repleted state, a large fraction of the IC became bound to erythrocytes during IC infusion, which resulted in lower plasma IC concentrations. Under these conditions, a more gradual rate of disappearance of IC from the circulation was observed. The relatively abrupt clearance of IC from the circulation in the complement-depleted state could not be accounted for by increased hepatic or splenic uptake. These data indicate that, in contrast to previous studies in nonprimates, complement depletion in primates results in accelerated removal of IC from the circulation. This suggests that factors such as hypocomplementemia and deficient expression of erythrocyte CRI, which are known to occur in certain IC-mediated diseases, may promote IC uptake by organs vulnerable to IC-mediated injury.

Differential binding of immunoglobulin A and immunoglobulin G1 immune complexes to primate erythrocytes in vivo. Immunoglobulin A immune complexes bind less well to erythrocytes and are preferentially deposited in glomeruli

Primate erythrocytes appear to play a role in the clearance of potentially pathogenic immune complexes (IC) from the circulation. This study was undertaken to compare the clearance from the circulation and tissue uptake of two monoclonal IC probes: one of which, IgG1-IC, was bound well by erythrocytes, the other of which, IgA-IC, was bound relatively poorly by erythrocytes. The IC probes were labeled with different iodine isotopes and infused either concomitantly or sequentially into the arterial circulation. The results indicate that, compared with IgG1-IC, IgA-IC bind less well to primate erythrocytes, are cleared from the circulation more quickly despite their smaller size, and show increased uptake in kidney and lung but decreased uptake in liver and spleen. Evidence is presented which suggests that this pattern of clearance from the circulation and systemic uptake of IgA-IC is the result of decreased binding of IgA-IC to circulating erythrocytes. These findings support the hypothesis that the primate erythrocyte-IC clearing mechanism may be critically important for the safe removal of IC from the circulation.

Prospective evaluation of magnetic resonance imaging in the management of acute diabetic foot infections

Infectious complications of the foot are a major cause of morbidity and mortality in diabetic patients. This prospective study evaluated the ability of MRI to adequately direct the medical and surgical management of 41 diabetic patients with acute foot infections. Forty-seven MRI scans of the foot in question were performed and classified as consistent with osteomyelitis, abscess, cellulitis or diffuse soft tissue infection, or any combination of these. Twenty-seven scans were negative or showed ill-defined soft tissue infection, or superficial cellulitis. Nineteen of these infections were treated nonoperatively and 17 resolved without surgical intervention. MRI was unsuccessful in directing management in one patient in whom an abscess spontaneously drained but was not seen on an MRI scan 4 days earlier. Eight scans revealed focal osteomyelitis and all eight of these patients were successfully managed with one operation. MRI showed a focal abscess in 12 patients, and adequate drainage was achieved without excessive disruption of uninvolved tissue planes in 11 of these patients. The remaining patient required a major amputation from the outset. Based on clinical outcome during the acute hospitalization period, operative findings, and/or pathologic confirmation, the positive predictive value of MRI in defining infectious pathology in the foot was 100% in this series of 20 positive scans. The negative predictive value of MRI was 96%. On the basis of this experience, we conclude that MRI is a diagnostic modality particularly well suited to evaluate acute diabetic foot infections and reliably aids in the management of acute infection to avoid exploration and debridement of uninvolved tissue. Furthermore, MRI was able to reliably define the site and extent of infection and allow effective surgical management.

Percutaneous Transluminal Angioplasty of Tibial Arteries for Limb Salvage in the High-Risk Diabetic Patient

Recent advances in balloon catheter technology allow percutaneous transluminal angioplasty (PTA) of small arteries such as the tibial arteries. PTA can thus be used to treat lower limb ischemia in diabetic patients whose arterial occlusive disease is often localized to the tibial arteries. This series included 14 consecutive diabetic patients who underwent tibial PTA for treatment of limb-threatening ischemia from 1986 to 1992. PTA was selected over conventional bypass procedures because of a lack of autogenous conduit or because of an unacceptably high surgical risk. Limb loss was imminent without prompt improvement in foot perfusion in all patients. Mean follow-up of 17 months demonstrated long-term limb salvage in 10/13 (77%) and “late” cardiac-related death in 3/13 (23%). This series demonstrates that although conventional arterial bypass should routinely supersede angioplasty procedures, tibial PTA offers the opportunity for limb salvage in diabetic patients with inadequate autogenous conduit for distal tibial bypass and may serve as an option for those who are considered too high risk for conventional bypass. Morbidity and mortality rates of tibial PTA parallel those of major amputation in this population with the obvious benefit of achieving limb salvage in carefully selected diabetic patients.

Randomized trial of emergency mesocaval and portacaval shunts for bleeding esophageal varices

A randomized trial of emergency portacaval or mesocaval shunting was conducted in twenty-four cirrhotic patients bleeding from esophageal varices. The group of eleven patients having mesocaval shunts was comparable to the group having portacaval shunts in age distribution, sex, and preoperative physical condition. Postoperative fatality rates were 46% after portacaval shunting and 73% after mesocaval shunting. Results favor portacaval shunts for the emergency control of bleeding varices in the spectrum of patients seen in an urban hospital.

Pediatric thoracic outlet syndrome: a disorder with serious vascular complications

BACKGROUND Thoracic outlet syndrome (TOS), caused by compression of the neurovascular structures between the clavicle and scalene muscles, typically presents with neurologic symptoms in adults. We reviewed our experience with 25 adolescents and propose a diagnostic/treatment algorithm for pediatric TOS. METHODS From 1993 to 2005, 25 patients were treated with TOS. A retrospective chart review was performed with institutional review board approval. Demographics, clinical presentation, diagnostic studies, and treatment were evaluated. RESULTS Seven male (28%) and 18 female (72%) patients presented between the ages of 12 to 18 years. Thirteen (52%) had vascular TOS (11 venous, 2 arterial), 11 (44%) had neurologic TOS, and 1 had both. Vascular TOS included subclavian vein thrombosis (7), venous impingement (4), and arterial impingement (2). Three patients had hypercoagulable disorders, and 6 had effort thrombosis. Venography was diagnostic in 10 cases. Neurogenic TOS was diagnosed by clinical symptoms. Five patients with subclavian vein thrombosis underwent thrombolysis, with 3 maintaining long-term patency. Of 25 patients, 24 underwent transaxillary first rib resection. CONCLUSION Vascular complications are more common in adolescents with TOS than in adults. A diagnostic/treatment algorithm includes urgent venography and thrombolysis for venous TOS and a workup for hypercoagulability. Neurogenic TOS is diagnosed clinically, whereas other studies are rarely beneficial.

Safety of simultaneous aortic reconstruction and renal transplantation

Patients with aortic disease and end-stage renal failure who require both aortic reconstruction and renal transplantation (simultaneously or staged) pose a formidable clinical challenge. Traditionally, the performance of either one of these procedures has been viewed as a relative contraindication to the performance of the other. From 1978 to 1989, eight patients were referred to us with the combination of aortic disease and end-stage renal failure. Seven had aneurysmal disease and one had aorto-iliac occlusive disease. Five patients presented with their diseases sequentially and had two sequential operations, with a mean interval of 4 years between procedures. Three patients presented with their diseases simultaneously and underwent simultaneous aortic reconstruction and living related renal transplantation. All patients were followed up for a mean interval of 4.5 years. By life-table analysis, the 5-year renal graft survival was 100%, the primary aortic graft patency was 82%, and the secondary aortic graft patency was 100%. The only death in this series occurred 11 years after aortic reconstruction and 4 months after a renal transplantation and was due to overwhelming cytomegalovirus sepsis. There were no significant differences between the simultaneous and staged groups in terms of operative mortality, postoperative complications, transplant function, or aortic graft patency. From this experience, we conclude that: (1) patients who present simultaneously with aortic disease and end-stage renal failure can safely undergo simultaneous aortic reconstruction and renal transplantation; (2) patients who present with these two diseases sequentially can undergo a second reconstructive procedure with very low operative morbidity and mortality rates; (3) when these two procedures have been performed sequentially, the second procedure has not significantly altered the 30-day or 5-year results of the first procedure; and (4) the 30-day and 5-year results of each procedure have been excellent regardless of the temporal sequence in which they were performed.

Saphenous Vein Stripping and its Complications

Saphenous vein stripping is one of the most common general surgical operations. Complications are rare and seldom serious; they can be fur- ther minimized by careful patient selection and meticulous technique. Adherence to the basic principles described should help further reduce the complication rate and maximize therapeutic benefit.

Surgical correction of abdominal aortic coarctation and hypertension

Coarctations of the abdominal aorta are often associated with renal artery stenosis resulting in hypertension, which is commonly the presenting symptom. Controversy exists concerning the origin of these lesions, but there is general agreement that surgical intervention is the treatment of choice. We report four patients with abdominal aortic coarctation and concomitant renal artery stenosis who required aortoaortic bypass and appropriate bypass to the renal vessels. We advise total correction in one stage and proximal renal artery bypass from native aorta or iliac artery when it is technically feasible.

Vertical ramus osteotomy for improved exposure of the distal internal carotid artery: A new technique

Access to the internal carotid artery distal to a line drawn from the angle of the mandible to the tip of the mastoid process may be compromised (Fig. 1).1 The angle and ramus of the mandible overlie this segment of the distal internal carotid artery (the paraatlantoaxial segment) from a few centimeters after its origin and distally to its entry into the carotid canal. Even when the exposure is sufficient to display the arterial lesion, the mandible obstructs vision of other vital strucmres, especially the cranial nerves in the region, and may compromise surgical maneuvers involved in repair of the vessel. Access may be necessary for repair of traumatic injury to the distal internal carotid or for endarterectomy. Previously recommended aids to exposure have included anterior mandibular -subluxation or dislocation and mandibular osteotomy. Subluxation and dislocation may be associated with inadequate access. Previously recommended osteotomies fail to use modern maxillofacial principles including the use of rigid internal .fixation. The vertical ramus, osteotomy is ideal for allowing improved access to the distal internal carotid artery, can be accomplished through the standard surgical exposure needed for access to the vessel, requires minimal additional surgical time, and is associated with little additional morbidity. The technique recommended requires rigid internal fixation with bone plates, which are adapted to the ramus and. have screw holes drilled before osteotomy to assure exact repositioning of the osteotomized segments.