Glenn C. Hunter

Distal revascularization–interval ligation for limb salvage and maintenance of dialysis access in ischemic steal syndrome☆☆☆★

PURPOSE Traditional options for treating ischemic steal syndrome related to a functioning dialysis access graft or fistula include banding or ligation. Unfortunately, these techniques usually result in inconsistent limb salvage, loss of a functional access, or both. We report our experience with an alternative method of limb revascularization that eliminates steal while maintaining continuous dialysis access. METHODS Patients who had critical limb ischemia and functioning arteriovenous fistulae (AVF) underwent color-flow duplex scanning, digital photoplethysmography, and arteriography. Arterial ligation distal to the AVF origin eliminated the steal physiologic mechanism while arterial bypass grafting from above to below the AVF revascularized the extremity (distal revascularization-interval ligation [DRIL] procedure). RESULTS From March 1994 through December 1996, 21 patients with functioning extremity AVFs presented with critical ischemia and steal syndrome. Eleven patients had chronic ischemia with rest pain, paresthesias, or ulcerations related to nine native fistulae (six brachiocephalic, two basilic vein transpositions, one radiocephalic) and two prosthetic bridge grafts (one upper arm, one lower extremity). Acute ischemia developed in 10 patients related to three native fistulae (two brachiocephalic, one radiocephalic) and seven prosthetic bridge grafts (three forearm, three lower extremity, one upper arm). All 21 patients were treated with the DRIL technique. Three of these patients required treatment for ischemia at the time of AVF construction. Nineteen of 21 bypass procedures were performed with autogenous vein, including nine brachial-brachial, three brachial-radial, two radial-radial, two brachial-ulnar, one popliteal-popliteal, one femoral-popliteal, and one femoral-peroneal. Polytetrafluoroethylene grafts were used for one external iliac-popliteal bypass graft and one axillary-brachial bypass graft. Limb salvage and maintenance of a functional fistula were achieved in 100% and 94%, respectively, at 18 months by life-table analysis. CONCLUSION The DRIL technique reliably restores antegrade flow to the ischemic limb, eliminates the potential pathway for the steal physiologic mechanism, and maintains continuous dialysis access in these difficult patients.

Contrast-induced nephrotoxicity: The effects of vasodilator therapy☆

The increasingly frequent use of contrast-enhanced imaging for diagnosis or intervention in patients with peripheral vascular disease has generated concern about the incidence and avoidance of contrast-induced nephrotoxicity (CIN). In this prospective study, we sought to identify those patients at greater risk of developing CIN and to evaluate the efficacy of vasodilator therapy with dopamine in limiting this complication. Baseline serum creatinine (Cr) concentrations were obtained on admission and daily for up to 72 hr after angiography in 222 patients undergoing 232 angiographic procedures. The preangiographic treatment was varied at 2-month intervals for 1 year. All patients received an intravenous infusion of 5% dextrose and 0.45% normal saline at a rate of 75 to 125 ml/hr. During the first interval patients received 12.5 g of 25% mannitol immediately prior to their contrast load, in addition to intravenous fluids. During the next 2-month period the patients were given renal dose dopamine intravenously (3 micrograms/kg/min) commencing the evening before angiography and continued to the next morning. During the latter half of the study the treatment regimens were modified so that the use of mannitol was restricted to patients with diabetes mellitus and dopamine to patients with serum creatinine concentrations of > or = 2 mg/dl. Postangiographic elevation in Cr occurred in 2, 10.4, and 62% of studies in patients with baseline creatinine levels of < or = 1.2 mg/dl, 1.3 to 1.9 mg/dl, and > or = 2.0 mg/dl, respectively. None of the patients receiving dopamine experienced an elevation in creatinine. There was no statistical correlation between age, diabetes, or medication with calcium channel blockers and CIN.(ABSTRACT TRUNCATED AT 250 WORDS)

Current trends in the detection and management of carotid body tumors

PURPOSE Because the natural history of carotid body tumors is believed to be unpredictable, immediate surgical removal has been recommended. The present study reviews our experience in the diagnosis and treatment of these uncommon lesions. METHODS The medical records of patients who appeared for treatment with carotid body tumors between 1981 and 1997 were reviewed. Patients demographics, mode of presentation, imaging and treatment modalities, Shamblin classification, and neurologic complications (stroke, cranial nerve injuries) were analyzed. RESULTS Over the past 16 years, 31 patients with 32 carotid body tumors have been evaluated, with an average follow-up of 3.2 years. The patients were arbitrarily classified into two groups on the basis of the mode of detection. Seventy percent (23 of 32) of the tumors discovered on clinical or self-examination were classified as Group 1; 28% (9 of 32) of the tumors detected during duplex scanning for carotid artery disease (8) or MRI (1) were classified as Group 2. The mean size of chemodectomas found on palpation (4.3 +/- 1.7 cm) was larger than that of those detected by duplex ultrasound (2.7 +/- 1.0 cm; p < 0.05, by paired t test). Preoperative embolization was successfully performed in 5 of 6 instances of large tumors; the remaining patient suffered a procedure-related stroke. Thirty-one carotid body tumors were resected. In one case, the tumor was felt by the primary surgeon to be too small (0.9 x 0.7 cm on duplex scan) to warrant immediate excision; this patient is being followed by periodic duplex scanning. Five neurologic complications were noted in Group 1, one after preoperative embolization and four after surgery. One cranial nerve injury occurred in Group 2. One patient had a large recurrent chemodectoma with clinical evidence of metastatic disease. CONCLUSION The increasing use of sophisticated imaging modalities may allow earlier discovery of carotid body tumors before they can be clinically detected. Resection of carotid body tumors of all sizes in appropriate surgical candidates remains the standard of care. Unfortunately, resection of even small tumors is associated with a low but constant incidence of neurologic complications.

Clinical presentation and management of iatrogenic colon perforations

BACKGROUND Because iatrogenic colonic perforation is uncommon, surgical management of this complication has been based on the civilian trauma experience. In this study, we determine the incidence, clinical presentation, and management of colonic perforations resulting from colonoscopy or barium enema. PATIENTS AND METHODS The medical records of all patients with colorectal perforations due to barium enema or colonoscopy seen over a 5-year period were reviewed. RESULTS Twenty-one patients, 12 males and 9 females aged 66 +/- 16 years, undergoing evaluation for polyps and bleeding (11), diverticulosis (4), diarrhea (2), or miscellaneous indications (4) sustained colonic perforation from colonoscopy (18; 0.20%) or barium enema (3; 0.10%). Abdominal pain, 66% (13), and fever, 24% (5), were the most frequent symptoms encountered and extraluminal air, 67% (14), the most common radiologic finding. The site of perforation was the rectosigmoid in 62% (13) of patients. Eighteen patients underwent surgery; 11 within 24 hours (group I) and 7 patients within 6.0 +/- 4 days (group II). Fifty percent (9 of 18) had primary repair or resection with anastomosis without mortality. Of the 6 patients initially treated nonoperatively, 3 subsequently underwent surgery. Both deaths, one in group I and one in group II, occurred in patients who had colonic diversion for perforation following colonoscopy. CONCLUSION We conclude that in the absence of significant contamination either primary repair or resection and anastomosis can be performed with acceptable morbidity for iatrogenic perforations of the colon.

Morphologic characteristics of varicose veins: possible role of metalloproteinases☆

BACKGROUND Although varicose veins are a common cause of morbidity, etiologic factors predisposing to dilatation, elongation, and tortuosity of the saphenous vein and its tributaries are poorly understood. We compared histologic features of normal and varicose saphenous veins and investigated the role of enzyme or inhibitor imbalance in development of varicosities. METHODS Eight normal and 10 varicose (C(2,3)E(P,S)A(S)P(R,O)) vein segments were used for this analysis. Matrix metalloproteinase (MMP) expression and activity were analyzed with Western blotting and zymography. Venous architecture and protein localization were determined with histology and immunohistochemistry. RESULTS Western blot analysis demonstrated the presence of MMP- 1, MMP-2, MMP-9, and MMP-12, as well as small quantities of tissue inhibitor of metalloproteinases (TIMP)-1 and TIMP-2 in protein isolates from normal and varicose veins. Both vein types demonstrated MMP-2, MMP-9, and MMP-12 activity by gelatin zymography, although varicose vein expressed less MMP-9 activity than normal vein did. Compared with normal veins, changes in varicose veins were not uniformly distributed along the circumference; areas of intimal thickening were often interspersed with focal areas of dilatation. Fragmentation of elastic lamellae and loss of circular and longitudinal muscle fibers were evident in the varicosities. Focal aggregates of macrophages were detected within the media and adventitia of both normal and varicose veins. MMP-1 and MMP-9 were expressed in both types of vein segments; however, their immunohistochemical localization was distinctly different. In normal vein, endothelial cells, occasional smooth muscle cells (SMC), and adventitial microvessels expressed MMP-1, whereas its expression was localized to fibroblasts, SMC, and endothelial cells throughout involved portions of varicose veins. MMP-9 was localized to endothelial cells, medial SMC, and adventitial microvessels in both normal and varicose veins, although varicose veins demonstrated increased medial smooth muscle cell staining. MMP-12 was found in SMC and fibroblasts in both normal and varicose veins. Neither TIMP-1 nor TIMP-2 were detected with immunohistochemistry in any specimens examined. CONCLUSIONS There are distinct differences in the structural architecture and localization of MMP expression in normal and varicose veins. Although the changes observed are not sufficiently definitive to enable a causal relationship, they do suggest a possible mechanism for the alterations in matrix composition observed between normal and varicose veins.

Management of chyloperitoneum after abdominal aortic surgery

Chyloperitoneum is a rarely reported complication of abdominal aortic surgery. From 1981 to 1992, we treated 5 cases of chylous ascites after operations on the abdominal aorta and reviewed 22 previously published cases. There were 22 men and 5 women, with a mean age of 63.8 years (range: 27 to 93 years). Twenty cases (74.7%) occurred after abdominal aortic aneurysm resection, 5 (18.5%) after aorto-femoral bypass for occlusive disease, and 2 (6.8%) after resection of infected aortic grafts, 1 for occlusive disease and the other for infrarenal aortic aneurysm. Abdominal distention was the most common presenting symptom, occurring in 26 (96.3%) of 27 patients. The mean time from aortic operation to the development of symptoms was 18.5 days (range: 7 to 120 days). Diagnosis was confirmed by paracentesis, which yielded lipemic, sterile fluid in all patients. Therapeutic paracentesis was not successful when used alone, but, when combined with a medium-chain triglyceride (MCT) diet or total parenteral nutrition (TPN), it resulted in resolution of chyloperitoneum in 8 of 14 patients (57.2%). TPN alone or with paracenteses and/or diuretics was successful in 9 of 15 (60%) patients. Peritoneovenous shunts resolved chylous ascites in four of five patients not responding to diet and/or TPN but resulted in one death due to sepsis. Operative ligation of the injured lymphatic channel was successful in all five patients treated by laparotomy when nonoperative efforts failed. Chyloperitoneum resolved in all but two (7.7%) patients. There were five (18.5%) deaths, but only three (11.5%) were directly related to chylous ascites. Treatment with TPN resolved chyloperitoneum in all five of our own patients. We reached the following conclusions: (1) Chyloperitoneum is a rare complication of aortic surgery; (2) This disorder should be considered whenever persistent abdominal distention appears after aortic surgery; (3) The diagnosis is easily confirmed by paracentesis; and (4) Surgery to close the lymph fistula should be reserved for those patients in whom conservative therapy with MCT diets or TPN has failed.

Popliteal vascular compression in a normal population

PURPOSE Positional popliteal artery obstruction is believed to be an important factor contributing to popliteal artery entrapment syndromes. This study was undertaken to define the positional anatomy and physiologic condition of the vessels in the popliteal fossa in groups of highly trained and normally active young men and women. We postulate that at least some symptom-free individuals can occlude the popliteal artery with leg positioning. METHODS Seventy-two limbs were evaluated in 36 subjects. Symptom-free subjects were recruited in four groups: normally active men, normally active women, male competitive runners, and female competitive runners. All subjects underwent noninvasive testing that included resting segmental limb pressures and Doppler waveforms and color-flow duplex imaging with the leg in the neutral position and then with knee extension with active and passive dorsiflexion and plantar flexion of the foot. Subjects unable to occlude the popliteal artery with positioning were then exercised, and studies were repeated. Magnetic resonance imaging, with magnetic resonance angiography, was conducted on 14 subjects, with each leg studied in the neutral position and with active positioning. RESULTS Positional popliteal arterial occlusion occurred in 38 of 72 limbs (53%). No intergroup comparisons were statistically significant. The response of each leg was symmetric in 89% of subjects. No subject who could not occlude the popliteal artery at rest was able to do so with exercise. Magnetic resonance imaging disclosed normal anatomy in all subjects and showed the location of popliteal occlusion to be at the level of the soleal sling, with positional compression by the soleus muscle, the lateral head of the gastrocnemius, the plantaris, and popliteus muscles. CONCLUSION Popliteal arterial occlusion can be induced in 53% of subjects with simple leg positioning caused by myofascial compression. This must be considered when evaluating patients for intervention on the basis of physiologic testing of the popliteal vessels.

Timing of carotid endarterectomy after acute stroke

An arbitrary delay of at least 6 weeks before performing carotid endarterectomy after acute stroke has been recommended based on anecdotal reports. This prolonged interval may increase the danger of recurrent neurologic deficit before surgery. From September 1978 to September 1988, carotid endarterectomy was performed on 140 patients at variable intervals after stroke. Eleven patients had temporary stroke, which left 129 patients with neurologic symptoms that persisted for 3 weeks or had a cortical infarct on CT scanning. A prospective therapeutic protocol was applied to 82 patients admitted with acute stroke. They were observed until neurologic recovery reached a plateau, based on clinical observation by a neurologist, before performing angiography and carotid endarterectomy (group I). Forty-seven patients were not seen until after recovery from stroke was established (group II). At initial presentation, the severity of neurologic deficit was classified as mild, moderate, or severe in 31%, 58%, and 11%, respectively. Recovery before operation was registered as complete in 11%, mild residual in 66%, moderate residual in 21%, and severe residual in 2%. Group I patients (n = 82, 64%) were operated on within 6 weeks of stroke and group II (n = 47, 36%) were operated on at varying times after 6 weeks. No significant difference was found in the incidence of cerebrovascular events (1.2% vs 4.2%) and deaths (1.3% vs 2.1%) between groups I and II with respect to the timing of carotid endarterectomy, and no significant difference was found between patients operated on at 2, 4, 6, or more than 6 weeks after stroke.(ABSTRACT TRUNCATED AT 250 WORDS)

Free tissue transfer to extend the limits of limb salvage for lower extremity tissue loss

BACKGROUND The extent of tissue loss amenable to primary healing after revascularization is unknown. Salvage of limbs with large soft-tissue defects with exposed tendon, joint, or bone lies beyond the limits of conventional techniques. We report our results using free tissue transfer as an adjunct to lower extremity vascular reconstruction in patients with complex ischemic or infected wounds. METHODS Retrospective chart review of patient and wound characteristics. RESULTS From January 1992 to June 1996, 585 procedures were performed in 544 patients, including 27 free flaps in 26 patients: 17 free flaps combined with distal bypass (7 staged, 10 simultaneous) and 10 isolated free flaps. Flap donor sites included radial forearm (8), latissimus dorsi (7), rectus abdominus (9), and scapula (3). Surgical indications included extensive ischemic/neurotrophic ulcers, and nonhealing vein graft harvest incision or transmetatarsal amputation site. Mean area of tissue loss was 70 cm2, mean ulcer duration was 5 months, and 92% of patients had exposed tendon, joint, or bone. During a mean follow-up of 14 months, 2 patients died of cardiopulmonary disease and 3 flaps failed, resulting in below-knee amputation. Six flaps were revised for graft stenosis (1), venous thrombosis (1), or flap edge necrosis (4). Limb salvage rate was 70% at 24 months by life-table analysis. Functional ambulation was achieved in 21 of 24 (88%) patients, including 7 of 8 with diabetes, end-stage renal disease, and heel ulcers. CONCLUSION In select ambulatory patients with large soft-tissue defects and exposed deep structures, functional limb salvage is obtainable in more than 80% of patients. For lesions not amenable to vascular reconstruction with conventional methods of wound coverage, free tissue transfer extends the limits of limb salvage and is a viable alternative to amputation.

Distinguishing Carotid Artery Pseudo-Occlusion With Color-Flow Doppler

BACKGROUND AND PURPOSE This study was undertaken to determine the impact of color-flow Doppler on the accuracy of noninvasive carotid imaging for distinguishing an internal carotid artery pseudo-occlusion (string sign) from a complete occlusion. METHODS From January 1985 to January 1994, review of noninvasive vascular studies, arteriograms, and operative reports of 26 consecutive patients undergoing 27 carotid endarterectomies for carotid pseudo-occlusion was performed. Further review was conducted of all patients identified with carotid occlusion by noninvasive testing who underwent confirmatory arteriography during the same interval. RESULTS Conventional gray-scale duplex scanning (January 1985 to December 1989) correctly identified 3 of 11 (27%) pseudo-occluded internal carotid arteries compared with 15 of 16 (94%) internal carotid artery pseudo-occlusions correctly identified by color-flow Doppler (January 1990 to June 1994) (P < .01). Similarly, carotid occlusion was more accurately identified by color-flow Doppler (33 of 33, 100%) compared with gray-scale duplex scanning (19 of 27, 90%) (P < .01). CONCLUSIONS The addition of color-flow Doppler to the duplex evaluation of the extracranial carotid circulation improves the accuracy of distinguishing carotid pseudo-occlusion from the occluded internal carotid artery and may obviate the need for arteriography to identify patients with this critical level of carotid stenosis.