Ischemic colitis

This article contains a current review of ischemic colitis, including its etiology, pathophysiology, diagnostic modalities, and treatment options. A special emphasis is given to ischemic colitis following aortic reconstruction.

Decreased vascular smooth muscle cell density in medial degeneration of human abdominal aortic aneurysms

Abdominal aortic aneurysms (AAAs) are characterized by structural deterioration of the aortic wall leading to progressive aortic dilatation and eventual rupture. The histopathological changes in AAAs are particularly evident within the elastic media, which is normally dominated by vascular smooth muscle cells (SMCs). To determine whether a decrease in vascular SMCs contributes to medial degeneration, we measured SMC density in 21 normal and pathological human abdominal aortic tissue specimens using immunohistochemistry for alpha-SMC actin and direct cell counts (medial SMCs per high-power field (HPF)). Medial SMC density was not significantly different between normal aorta (n = 5; 199.5 +/- 14.9 SMCs/HPF) and atherosclerotic occlusive disease (n = 6; 176.4 +/- 13.9 SMCs/HPF), but it was reduced by 74% in AAA (n = 10; 50.9 +/- 6.1 SMCs/HPF; P < 0.01 versus normal aorta). Light and electron microscopy revealed no evidence of overt cellular necrosis, but SMCs in AAAs exhibited ultrastructural changes consistent with apoptosis. Using in situ end-labeling (ISEL) of fragmented DNA to detect apoptotic cells, up to 30% of aortic wall cells were ISEL positive in AAAs. By double-labeling techniques, many of these cells were alpha-actin-positive SMCs distributed throughout the degenerative media. In contrast, ISEL-positive cells were observed only within the intimal plaque in atherosclerotic occlusive disease. The amount of p53 protein detected by immunoblotting was increased nearly fourfold in AAA compared with normal aorta and atherosclerotic occlusive disease (P < 0.01), and immunoreactive p53 was localized to lymphocytes and residual SMCs in the aneurysm wall. Using reverse transcription polymerase chain reaction assays a substantial amount of p53 mRNA expression was observed in AAAs. These results demonstrate that medial SMC density is significantly decreased in human AAA tissues associated with evidence of SMC apoptosis and increased production of p53, a potential mediator of cell cycle arrest and programmed cell death. Given the role that SMCs normally play in maintaining medial architecture and in arterial wall matrix remodeling, the induction of SMC apoptosis likely makes an important contribution to the evolution of aneurysm degeneration.

Role of matrix metalloproteinases in abdominal aortic aneurysms

Considerable progress has been made toward characterizing the enzymes and proteolytic events that occur in established human abdominal aortic aneurysms (AAA). Through studies involving a number of different laboratories and various experimental approaches, enzymes of the matrix metalloproteinase (MMP) family have consistently emerged as important molecular participants in aneurysm disease. The finding that elastolytic MMPs, particularly MMP-9 and MMP-2, are expressed and produced in increased amounts in human aneurysm tissue, has led to the possibility that these enzymes might serve as rational targets for pharmacotherapy in this disease. Recent studies using MMP-inhibiting tetracycline derivatives in the elastase-induced rodent model of AAA indicate that metalloproteinase suppression is a feasible and successful approach in the experimental setting. The definitive proof-of-principle for the therapeutic efficacy of anti-MMP or other anti-proteinase strategies to limit the growth of small AAA, however, will remain unknown until specifically tested in clinical trials.

Revascularization of the solitary kidney: a challenging problem in a high risk population

BACKGROUND

Patients with significant atherosclerotic stenosis involving the artery to a solitary functioning kidney present a clinical challenge.

METHODS

From August 1987 through August 1995, 35 of these patients (average age, 68.4 +/- 6.9 years) were treated. Comorbid conditions included previous myocardial infarction in 23% of the patients, congestive heart failure (CHF) in 34%, chronic obstructive pulmonary disease in 20%, and diabetes in 20%. The average creatinine level of the patients was 2.5 +/- 1.5 mg/dl. Indications for revascularization were hypertension in 86%, hypertensive crisis with CHF in 17%, and renal insufficiency in 69%. Procedures performed included 19 extra-anatomic bypasses, 8 concomitant with infrarenal aortic reconstruction and 2 concomitant with thoracoabdominal aortic aneurysm repair; 1 visceral segment endarterectomy; 1 renal artery endarterectomy with reimplantation; I superior mesenteric to renal artery bypass; 1 aortorenal bypass; and 2 percutaneous angioplasties with staged nephrectomies.

RESULTS

At discharge, 91% of patients had stable or improved renal function with an average creatinine level of 1.7 +/- 0.8 mg/dl. Hypertension was cured or improved in 85%. Perioperative mortality was 6%, and major morbidity was 43%, including the need for permanent (9%) and temporary (9%) dialysis, respiratory insufficiency (18%), two early reoperations, six cardiac complications, one case of gastrointestinal bleeding, and one stroke. In the follow-up period (mean duration, 39.2 months), survival has been 73%, and no additional patients have required dialysis.

CONCLUSIONS

Although significant perioperative morbidity exists in this high risk population, the long-term preservation of renal function and improvement in hypertension make solitary renal revascularization worthwhile.

Basic science of abdominal aortic aneurysms: emerging therapeutic strategies for an unresolved clinical problem

Abdominal aortic aneurysms (AAAs) are an increasingly common and potentially lethal condition. Surgical repair of AAA is now yet performed quite safely, yet ruptured AAAs still carry mortality rates of 50% to 70%. Ultrasound screening may help identify unsuspected AAA, thereby allowing elective repair. Because AAAs too small to warrant operation still expand progressively, therapeutic approaches to suppress AAA growth would be welcome. Current concepts indicate that AAAs arise through pathophysiologic process distinct from occlusive atherosclerosis and dominated by degenerative changes in the elastic media. These include marked alterations in elastin and collagen, chronic inflammation, and features of autoimmunity, medial neovascularization, and a decrease in vascular smooth muscle cells. Proteinases associated with mononuclear inflammatory cells, particularly matrix metalloproteinases, likely mediate the degradation of structural proteins in the aortic wall. Experimental studies demonstrate that similar processes occur in an elastase-induced rodent model of AAA, providing a means by which to develop novel therapeutic strategies for this disease. Pharmacologic inhibitors of matrix metalloproteinases act to suppress aortic elastin degradation and limit the growth of experimental AAA in vivo, suggesting at least one approach that may be useful in clinical application. Further developments can be expected to increase knowledge of the pathophysiology underlying aortic aneurysm disease, ultimately providing new therapies for small AAAs based on sound understanding of disease mechanisms.

Intraoperative salvage in patients undergoing elective abdominal aortic aneurysm repair: an analysis of cost and benefit

PURPOSE

Although autologous blood procurement has become a standard of care in elective surgery, recent studies have questioned its cost-effectiveness. We therefore reviewed our 3-year experience with intraoperative cell salvage in patients who underwent elective abdominal aortic aneurysm repair.

METHODS

A 3-year retrospective chart review of elective abdominal aortic aneurysm (infrarenal and suprarenal) repair was performed. Transthoracic repairs were excluded.

RESULTS

Estimated blood lost was 1748 +/- 1236 ml, or 35% of baseline blood volume (5012 +/- 689 ml). Overall, 164 (89%) received red blood cell (RBC) transfusions (3.5 +/- 2.0 U/patient). The cost per patient for cell salvage was $315 +/- $97, representing 31% of all RBC costs and 24% of total blood component costs. Mean salvage volume infused was 578 +/- 600 ml; at a mean hematocrit level of 55.7% the RBC volume infused from salvage during surgery was 313 +/- 328 ml (representing 27% of total RBC volume lost during the hospital stay). This mean RBC volume salvaged represented the equivalent of 1.6 blood bank RBC units. The mean blood bank costs saved by using cell salvage was $248, or 79% of the $315 actually spent for salvage. We found no decrease in percentage of patients undergoing transfusion until salvage volumes that were infused exceeded 750 ml, or the equivalent of two blood bank units; all of these patients who benefitted had estimated blood lost > or = 1000 ml.

CONCLUSIONS

We conclude that use of intraoperative cell salvage was most beneficial for patients who had estimated blood loss greater than or equal to 1000 ml and cell salvage volumes infused greater than or equal to 750 ml. Patients who are estimated to lose less than 1000 ml receive little benefit yet incur substantial costs from intraoperative cell salvage.

A longitudinal evaluation of prevalent negative beliefs about residential placement for troubled adolescents

To investigate the validity of five prevalent negative beliefs about residential placement, we followed adolescents from a residential program and a comparison group at 3-month intervals for 4 to 8 years. This residential program in the Midwest uses the Teaching-Family Model in which six to eight adolescents live in a family-style environment. The interviews included five scales reflecting youths' views about important aspects of their lives in placement: (1) Delivery of Helpful Treatment, (2) Satisfaction with Supervising Adults, (3) Isolation from Family, (4) Isolation from Friends, and (5) Sense of Personal Control. Hierarchical linear modeling allowed us to estimate group differences while controlling for developmental trends, demographic factors, and prior differences between groups. The two groups were equivalent on all scales before the study. During the following placement, however, the treatment group's ratings were significantly more positive than the comparison group on four of the five scales and approached significance on the fifth. These findings suggest that negative beliefs about life in residential placement for adolescents may not apply to all programs.

Indomethacin prevents elastase-induced abdominal aortic aneurysms in the rat

Perfusion of the rat abdominal aorta with elastase induces abdominal aortic aneurysms (AAA), in which the development of aortic dilatation correlates with the influx of inflammatory cells, increased production of matrix metalloproteinases (MMPs), and destruction of medial elastin. We tested the hypothesis that indomethacin, an inhibitor of macrophage MMP expression, might attenuate aneurysmal degeneration in this model. Fourteen adult male Wistar rats underwent 2-hr aortic perfusion with elastase. Six animals received injections of saline and eight animals received 4 mg/kg/day indomethacin for 7 days. Pre-perfusion, post-perfusion, and final aortic diameters (AD) were determined, and histology and substrate gel zymography were performed. Five out of six control animals developed AAA, while no aneurysms were observed in the indomethacin-treated group (P < 0.01). Whereas AD increased 126 +/- 16% in control animals, the mean increase in the indomethacin-treated group was only 56 +/- 6% (P < 0.001). Although animals in both groups demonstrated an inflammatory response dominated by macrophages, the marked destruction of medial elastin in the control group was not present in the treatment group. In addition, substrate zymography demonstrated decreased levels of MMP-9 in animals treated with indomethacin. Indomethacin inhibits aneurysm growth in this model, and the data suggest that it does so by decreasing macrophage expression of at least one elastolytic metalloproteinase, MMP-9.

Effects of ultraviolet light in vascular cells in vitro and in intact atherosclerotic explants: potential role of apoptosis in vascular biology

Complex cell-to-cell interactions are known to participate during vascular injury and remodeling, resulting in smooth muscle cell proliferation. Mechanical interventions have yielded little benefit in limiting this process and several site-specific genetic therapies are not yet clinically available. The aim of this study was to delineate the effect of very short wavelength ultraviolet (UVC) light therapy on the viability of macrophage and smooth muscle cells. Vascular cells were both treated in vitro and in intact explanted atherosclerotic aortic segments ex vivo with UVC light. Brief exposure to short wavelength UVC light in the absence of photosensitizers elicited a differential temporal and functional response among treated cells. However, dramatic reduction in both cellular viability and proliferative capacity with eventual cell demise was observed in all UVC-treated cells. Flow cytometry and immunohistochemical analyses revealed the presence of extensive DNA fragmentation, suggestive of apoptosis as a predominant pathway of cell death in these cells exposed to UVC light. We hypothesize that selective induction of apoptosis, in contrast to necrosis, with UVC light may represent a beneficial approach to interdict the complex biologic cascade of messengers that participate in the restenotic response to vascular injury.

Femoropopliteal bypass for claudication: vein vs. PTFE

The vascular graft of choice for femoropopliteal bypass in patients with intolerable claudication is controversial. We retrospectively reviewed our experience with 239 patients suffering from claudication secondary to superficial femoral artery obstruction. Femoropopliteal reconstruction was performed with saphenous vein to the below-knee popliteal artery in 66 patients (BK-vein). Polytetrafluoroethylene (PTFE) was used in 128 patients as a bypass graft to the above-knee popliteal artery (AK-PTFE) and 45 patients had a PTFE graft to the below-knee popliteal artery (BK-PTFE). All patients were enrolled in a postoperative graft surveillance program with graft revision when appropriate. There was one perioperative death (0.4%). Primary patency at 5 years for AK-PTFE, BK-PTFE, and BK-vein was 58.0%, and 60.3%, respectively, and was not significantly different among the graft groups. Graft revision for failed/failing grafts resulted in 5-year secondary patency rates of 79.2% (AK-PTFE), 73.3% (BK-PTFE), and 74.4% (BK-vein). These secondary patency rates were not statistically different. Eventual conversion to a vein graft in patients initially treated with PTFE maximized patency in the femoropopliteal segment with 5-year patency rates of 84.6% and 93.0% for the AK-PTFE and BK-PTFE graft groups, respectively. Major leg amputation was necessary during the entire course of the study in eight (3.3%) patients. We conclude that long-term patency rates for femoropopliteal bypass in patients with intolerable claudication are similar for PTFE and autologous saphenous vein grafts.

Development and comparison of transperitoneal and retroperitoneal approaches to laparoscopic-assisted aortofemoral bypass in a porcine model

PURPOSE

Transperitoneal and retroperitoneal approaches to video-assisted aortofemoral bypass were developed and compared using gasless laparoscopic techniques in a porcine model.

METHODS

Ten pigs were randomized to either a transperitoneal or retroperitoneal approach. Aortic clamp time, total operative time, and complications were recorded. Both operations used an external lift device to maintain the working space. Retroperitoneal operations first used serial balloon inflation to dissect the retroperitoneum. After exposure of the infrarenal aorta, a graft was tunneled under endoscopic visualization. End-to-side aortic and femoral anastomoses were created with conventional instruments through 4 cm incisions.

RESULTS

Mean +/- SEM aortic clamp time, operative duration, and graft patency rates were similar for both approaches (difference not significant by unpaired t test). Intraoperative complications related to the use of the laparoscopic technique included injury to the bladder and small bowel (n=2) and occurred only in the transperitoneal group.

CONCLUSIONS

The use of a gasless technique allowed direct visualization, standard instrumentation, and conventional anastomotic techniques. The retroperitoneal approach used the peritoneal sac to exclude the bowel, simplifying the aortic dissection. Gasless laparoscopic-assisted aortofemoral bypass can be performed by both transperitoneal and retroperitoneal approaches and holds promise as a minimally invasive treatment for aortoiliac occlusive disease.

Doxycycline inhibition of aneurysmal degeneration in an elastase-induced rat model of abdominal aortic aneurysm: preservation of aortic elastin associated with suppressed production of 92 kD gelatinase

PURPOSE

Increased local production of matrix metalloproteinases (MMPs) is a potential mechanism underlying structural protein degradation in abdominal aortic aneurysms (AAA). With an elastase-induced rodent model of AAA, we determined whether pharmacologic treatment with an MMP-inhibiting tetracycline might limit the development of experimental AAA in vivo.

METHODS

Forty-eight Wistar rats underwent a 2-hour perfusion of the abdominal aorta with 50 U porcine pancreatic elastase and were then treated with either subcutaneous doxycycline (25 mg/day; n=24) or saline solution vehicle (n=24). Aortic diameter was measured before and after elastase perfusion was performed and before the rats were killed at 0, 2, 7, or 14 days, and AAAs were defined as an increase in aortic diameter to at least twice that before perfusion. At death the aortic tissues were either perfusion-fixed for histologic evaluation or extracted for substrate zymographic evaluation.

RESULTS

Aortic diameter was not different between groups at 0 or 2 days, but it was significantly less in animals treated with doxycycline at both 7 and 14 days (mean+/-SEM, p<0.01). After day 2 the incidence of AAA was reduced from 83% (10 of 12 rats treated with saline solution) to 8% (1 of 12 animals treated with doxycycline). By histologic assessment doxycycline prevented the structural deterioration of aortic elastin without decreasing the influx of inflammatory cells. Increased aortic wall production of 92 kD gelatinase observed in a saline solution-treated control group was markedly suppressed in animals treated with doxycycline.

CONCLUSIONS

Treatment with an MMP-inhibiting tetracycline inhibits the development of experimental AAA in vivo. This inhibition may be due to selective blockade of elastolytic MMP expression in infiltrating inflammatory cells. Additional experiments, however, are necessitated to fully delineate this process.

Effect of the slow-component rise in oxygen uptake on VO2max

During constant-rate high-intensity (CRHI) exercise lasting longer than 3 min, VO2 has been reported to exceed VO2max measured with a traditional graded exercise test (GXT). This could be because VO2max was not achieved on the GXT or because the factors responsible for the slow-component rise in VO2 alter VO2max. The objective of this study was to test the hypothesis that the slow-component rise in VO2 measured during CRHI running leads to a total VO2 that exceeds VO2max measured during a running GXT. VO2max was determined in eight highly trained individuals using data collected from five grade-incremented, treadmill-running GXT. Each subject demonstrated a definitive plateau of VO2 as a function of exercise intensity. Three VO2max values based on different approaches for representing the VO2max plateau were obtained. Subjects also completed two exhaustive CRHI bouts of treadmill running lasting 7-13 min at speeds estimated from the ACSM equation to elicit an average of 99 +/- 5% VO2max. The mean (+/- SD) VO2peak determined during the CRHI runs (4.17 +/- 0.9 l.min-1) was not different form or less than the three VO2max values (4.19-4.32 +/- 0.09 l.min-1). We conclude that in highly trained individuals, the slow-component rise in VO2 during CRHI treadmill running does not lead to a total VO2 that exceeds the VO2max measured during a running graded exercise test.

Limb salvage and patency after aortic reconstruction in younger patients

PURPOSE

The purpose of this report was to compare patient characteristics, treatment, and outcome in younger and older patients with aortoiliac occlusive disease.

METHODS

The medical records of 56 patients < or = 50 years of age (Group < or = 50) were retrospectively reviewed and compared to the records of 128 patients > or = 60 years of age (Group > or = 60). All patients were examined and treated between April 1987 and April 1994. Postoperatively, they were enrolled in a vascular laboratory surveillance program to serially monitor the status of the vascular reconstruction. Follow-up averaged more than 3 years in both groups and was available on greater than 90% of patients.

RESULTS

Patients in Group < or = 50 had a higher incidence of smoking (68% versus 51%) and a lower incidence of hypertension (29% versus 50%) than patients in group > or = 60 (smoking P = 0.03, hypertension P = 0.007). No other significant differences were noted among cardiovascular risk factors. Preoperative indications for surgery were similar among patients in both groups. An aortoiliac endarterectomy was more commonly used to revascularize the lower extremities in younger patients than in their older counterparts (23% versus 7%, P = 0.002). Graft revisions were more frequently necessary after aortic reconstruction in Group < or = 50 than in Group > or = 60 (29% versus 8%, P = 0.0003); however patency rates computed by life table analysis were not significantly different. The primary patencies for Group < or = 50 and Group > or = 60 at 5 years were 64% and 67%, respectively; their secondary patency rates at 5 years were 84% and 89%, respectively. No significant difference was found in major limb amputation (8% in Group < or = 50 versus 5% in Group > or = 60, P = 0.46). We conclude that aortoiliac reconstruction for occlusive disease can be performed with similar secondary patency and amputation rates in young and old patients. However, close postoperative surveillance and frequent surgical revision are necessary to maintain patency and minimize amputation.

Production and localization of 92-kilodalton gelatinase in abdominal aortic aneurysms. An elastolytic metalloproteinase expressed by aneurysm-infiltrating macrophages

Abdominal aortic aneurysms (AAA) are characterized by disruption and degradation of the elastic media, yet the elastolytic proteinases involved and their cellular sources are undefined. We examined if 92-kD gelatinase, an elastolytic matrix metalloproteinase, participates in the pathobiology of AAA. Gelatin zymography of conditioned medium from normal, atheroocclusive disease (AOD), or AAA tissues in organ culture showed that all tissues produced 72-kD gelatinase. AOD and AAA cultures also secreted 92-kD gelatinase, but significantly more enzyme was released from AAA tissues. ELISA confirmed that AAA tissues released approximately 2-fold more 92-kD gelatinase than AOD tissue and approximately 10-fold more than normal aorta. Phorbol ester induced a 5.3-fold increase in 92-kD gelatinase secretion by normal aorta and AOD and an 11.5-fold increase by AAA. By immunohistochemistry, 92-kD gelatinase was not detected in normal aorta and was only occasionally seen within the neointimal lesions of AOD tissue. In all AAA specimens, however, 92-kD gelatinase was readily localized to numerous macrophages in the media and at the adventitial-medial junction. The expression of 92-kD gelatinase mRNA by aneurysm-infiltrating macrophages was confirmed by in situ hybridization. These results demonstrate that diseased aortic tissues secrete greater amounts of gelatinolytic activity than normal aorta primarily due to increased production of 92-kD gelatinase. In addition, the localization of 92-kD gelatinase to macrophages in the damaged wall of aneurysmal aortas suggests that chronic release of this elastolytic metalloproteinase contributes to extracellular matrix degradation in AAA.

Medial neovascularization in abdominal aortic aneurysms: a histopathologic marker of aneurysmal degeneration with pathophysiologic implications

PURPOSE

The purpose of this study was to characterize the distribution of aortic wall microvessels in normal aorta, atheroocclusive disease (AOD), and abdominal aortic aneurysms (AAA) and to evaluate whether medial neovascularization (MNV) is a reliable histopathologic marker of aneurysmal degeneration.

METHODS

Aortic tissue specimens (9 normal, 10 AOD, and 10 AAA) were examined for elastin with Verhoeff-van Gieson stain and for Ulex europaeus type I lectin, an endothelial-specific antigen, and laminin, a marker of basement membranes, by immunohistochemistry. The density of MNV was determined by morphometry of aortic sections stained for endothelium. The spatial distribution of aortic microvessels was compared with that of elastin destruction and chronic inflammation.

RESULTS

Evidence of medial neovascularization was generally not observed in normal aorta or AOD, whereas AAAs showed strong spatial correlations between MNV, disruption and degradation of elastin, and chronic inflammation in the outer aortic wall. Several specimens of AOD had focal areas of MNV associated with localized elastin fragmentation and monocytic infiltration located at the interface between the atherosclerotic plaque and the inner media. The density of MNV was about fifteenfold higher in AAA compared with normal aorta and about threefold higher compared with AOD (microvessels per high-power field): normal aorta, 0.77 +/- 0.28; AOD, 3.40 +/- 0.51; AAA, 11.32 +/- 1.58 (ANOVA, p < 0.001).

CONCLUSIONS

The presence and density of MNV in the abdominal aorta is a consistent histopathologic marker of aneurysmal degeneration that is spatially correlated with the destruction of elastin and chronic inflammation. The observation of focal MNV in some specimens of AOD, associated with partial elastin disruption, raises the possibility that early changes of aneurysm disease might develop by an extension of angiogenic/inflammatory processes from the atherosclerotic plaque into the aortic media.

Transabdominal versus retroperitoneal incision for abdominal aortic surgery: report of a prospective randomized trial

PURPOSE

The purpose of this study was to perform a randomized, prospective trial that compares the transabdominal with the retroperitoneal approach to the aorta for routine infrarenal aortic reconstruction.

METHODS

From August 1990 through November 1993, patients undergoing surgery for abdominal aortic aneurysm (AAA) disease or aortoiliac occlusive disease (AIOD) were asked to participate in a randomized trial comparing the transabdominal incision (TAI) to the retroperitoneal incision (RPI) for aortic surgery. One hundred forty-five patients were randomized, with 75 (41 with AAA and 34 with AIOD) in the TAI group and 70 (40 with AAA and 30 with AIOD) in the RPI group. There were no significant differences between the groups in terms of age, sex, postoperative pain control (epidural vs patient-controlled analgesia), or comorbid conditions, except for a higher incidence of chronic obstructive pulmonary disease in the TAI group (21 vs 8 patients).

RESULTS

The incidence of intraoperative complications was similar for both groups. After surgery, the incidence of prolonged ileus (p = 0.013) and small bowel obstruction (p = 0.05) was higher in the TAI group. Overall, the RPI group had significantly fewer complications (p < 0.0001). The overall postoperative mortality rate (two deaths) was 1.4%, with both occurring in the TAI group (p = 0.507). The RPI group also had significantly shorter stays in the intensive care unit (p = 0.006), a trend toward shorter hospitalization (p = 0.10), lower total hospital charges (p = 0.019), and lower total hospital costs (p = 0.017). There was no difference in pulmonary complications (p = 0.71). In long-term follow-up (mean 23 months), the RPI group reported more incisional pain (p = 0.056), but no difference was found in incisional hernias or bulges (p = 0.297).

CONCLUSIONS

We conclude that the RPI approach for abdominal aortic surgery is associated with fewer postoperative complications, shorter stays in the hospital and intensive care unit, and lower cost. There is, however, an increase in long-term incisional pain. Current methods of postoperative pain control seem to decrease the incidence of pulmonary complications.

Long-term effectiveness of extraanatomic renal artery revascularization

BACKGROUND

The efficacy of direct aortorenal bypass and renal artery endarterectomy are well established. The purpose of this study is to define better the results of extraanatomic renal revascularization procedures.

METHODS

From April 1987 to March 1993, 124 patients underwent renal artery revascularization. Forty-eight (39%) of them (33 women, 15 men; average age, 65.9 years) underwent 49 extraanatomic renal artery bypasses. Preoperative risk factors included smoking in 30 patients (61%), history of myocardial infarction in 14 (29%), diabetes mellitus in 11 (22%), congestive heart failure in nine (18%), chronic obstructive pulmonary disease in 11 (22%), and stroke in six (12%). The average creatinine level was 2.3 mg/dl. The average number of antihypertensive medications was 2.4. Thirty iliorenal, 10 gastroduodenal-renal, seven hepatorenal, and two splenorenal bypasses were performed together with 10 contralateral nephrectomies.

RESULTS

Six major postoperative complications occurred. There were no deaths. Forty-one (85%) of patients had improvement or cure of their hypertension. Seven (15%) of patients failed to respond to treatment, and three required subsequent nephrectomy. After operation the average creatinine level was 1.7 mg/dl and the average number of medications was 1.7. Mean follow-up period has been 23.2 months (range, 1 to 79 months).

CONCLUSIONS

Extraanatomic bypass proved to be efficacious in treating hypertension and preserving renal function and has an acceptable rate of morbidity and mortality. We conclude that these procedures are an acceptable alternative to direct aortorenal artery revascularization.

The influence of anesthetic technique on perioperative complications after carotid endarterectomy

PURPOSE

This study evaluated the influence of anesthetic techniques on perioperative complications after carotid endarterectomy.

METHODS

Perioperative complications, the use of a carotid artery shunt, the duration of the operative procedure and postoperative hospital course were retrospectively compared in 584 consecutive patients undergoing 679 carotid endarterectomies with use of either general anesthesia (n = 361) or cervical block regional anesthesia (n = 318). There was no significant difference in the preoperative medical characteristics between the two anesthetic groups. Symptomatic carotid artery disease was the indication for surgery in 247 (68.4%) patients receiving general anesthetics, whereas 180 (56.6%) patients treated with a cervical block anesthetic had a symptomatic carotid artery stenosis (p = 0.02).

RESULTS

The perioperative stroke rate and stroke-death rate for the entire series was 2.4% and 3.2%, respectively, and was not significantly different between the anesthetic groups or between patients with symptomatic or asymptomatic disease. A carotid artery shunt was used in 61 (19.2%) patients receiving a cervical block anesthetic and 152 (42.1%) patients treated with a general anesthetic (p < 0.0001). Use of cervical block anesthesia was associated with a significantly shorter operative time, fewer perioperative cardiopulmonary complications, and a shorter postoperative hospitalization when compared with general anesthesia. Multivariate risk factor analysis indicated that age greater than 75 years, operative time greater than 3 hours, and the use of a carotid artery shunt were all independent risk factors for perioperative cardiopulmonary complications. When a carotid artery shunt was not analyzed as a multivariate risk factor, then general anesthesia became a significant risk factor for perioperative cardiopulmonary complications (risk ratio 2.08; p = 0.04).

CONCLUSIONS

We conclude that cervical block anesthesia is safer and results in a more efficient use of hospital resources than general anesthesia in the treatment of patients undergoing carotid endarterectomy.

Simultaneous surgical management of aortic and renovascular disease

The results of simultaneous elective infrarenal aortic reconstruction and renovascular surgery were retrospectively reviewed in 102 patients who consecutively underwent operation. The perioperative mortality rate (0 to 54 days) was 5% (5 of 102). Renal function had returned to baseline or was improved at discharge in 89 of 97 (92%) surviving patients. The intraoperative use of renal hypothermia was an independent predictor of improved postoperative renal function, by multivariate analysis. Twenty-five of 29 (86%) patients with severe hypertension had improvement in their blood pressure on the same or fewer medications postoperatively (p = 0.0005). A retroperitoneal incision was associated with less intraoperative crystalloid fluid administration (p = 0.03), more rapid postoperative resumption of an oral diet (p = 0.04), and better long-term survival (p = 0.02) when compared with a transperitoneal incision. We conclude that the simultaneous repair of infrarenal aortic pathology and renovascular lesions is associated with an acceptable perioperative morbidity and preserves or improves renal function in the majority of patients. The frequent use of renal hypothermia and careful consideration of the route of operative exposure will lead to optimal results.

Aorta-left renal vein fistula syndrome caused by rupture of a juxtarenal abdominal aortic aneurysm: novel pathologic mechanism for a unique clinical entity

Spontaneous aorta-left renal vein fistula (ALRVF) caused by abdominal aortic aneurysm (AAA) is a rare form of intravascular aneurysm rupture. The literature series of ALRVF, updated here to 19 reported cases, demonstrates that patients with ALRVF present with a unique clinical syndrome characterized by abdominal or left flank pain (84%), a pulsatile abdominal mass (63%), abdominal bruit or murmur (63%), hematuria (100%), and nonfunction of the left kidney on functional imaging studies (100% of patients studied). Operative findings in ALRVF syndrome have included a large AAA (mean diameter 9.2 cm), with frank rupture in only three; in 17 of 19 patients (89%) the ALRVF was associated with a retroaortic left renal vein anomaly. The patient presented here had a large juxtarenal AAA with rupture into the left retroperitoneal space. The wide aneurysm neck and expanding hematoma created an avulsion of the second left lumbar vein from its junction with an anatomically normal (preaortic) left renal vein; the resulting renal vein tear allowed development of an arteriovenous communication that was responsible for the clinical presentation of ALRVF syndrome. The disease found here demonstrates a novel mechanism for the production of ALRVF syndrome in patients with juxtarenal AAA and otherwise normal pararenal venous anatomy.

Combined analysis of tall fescue steer grazing studies in the Eastern United States

The mixed-models procedure (MMP) was used to analyze pooled data sets from 12 independent studies conducted during the last 13 yr at nine locations in seven states to provide combined estimates of daily gains by beef steers (Bos taurus) grazing tall fescue (Festuca arundinacea Schreb.) pastures free of (E-) or infested (E+) at different levels with the endophytic fungus Acremonium coenophialum. Treatments included low-infestation (< or = 5% E+), moderate-infestation (> or = 20 to < or = 35% E+), and high-infestation (> or = 50 to < or = 97% E+) tall fescue pastures, and, in tall fescue-clover (Trifolium spp.) mixtures, pastures at the same E+ levels with approximately 25 and 10% clover in spring and summer stands, respectively. Spring, summer, and combined spring+summer data were analyzed separately. The MMP permitted estimation of the fixed effects of treatments over a broad inference space of future years and different tall fescue pastures over a wide geographic range; detected relationships that had not been apparent in the individual studies, such as the interactions between clover presence and E+ infestation levels; and provided a more coherent body of information than did the results obtained from each discrete study. Logistical and financial constraints that force undesirable compromises in the conduct of future grazing and other expensive or time-consuming research may be avoided by using MMP within the context of cooperative projects.

Dextrocholedocholithiasis: calculous obstruction complicating double ductus choledochus in an adult

Double ductus choledochus is a rare anomaly of the extrahepatic biliary tree in which the common bile duct is represented by two independent hepatic ducts. Patients with this abnormality may have unimpeded biliary drainage and remain symptom free, yet various forms of double ductus choledochus are occasionally encountered in patients undergoing operation for symptomatic cholelithiasis. We describe a patient in whom doubled biliary ducts were identified on exploration for cholecystectomy along with calculous obstruction of the right-sided duct (ductus choledochus dextri). This case illustrates the potential for significant injury to the biliary tree when double ductus choledochus is present. In addition to a means by which to manage this problem at the time of operation, a review of the literature, as well as a description of this rare embryologic abnormality, is presented.

Circumferential venolysis and paraclavicular thoracic outlet decompression for "effort thrombosis" of the subclavian vein

Effort thrombosis of the subclavian vein (Paget-Schroetter syndrome) has long been considered a primary thrombotic process, but recent experience suggests that it may commonly result from repeated mechanical compression. Increased awareness of the pathophysiology of this syndrome can allow timely, improved diagnostic screening and the use of specific surgical intervention to relieve the venous consequences. During the past 15 years we have treated six patients with mechanical compression in the thoracic outlet causing surgically correctable venous occlusive problems. There were four men and two women with an average age of 38 years (range 26 to 53 years). All patients exhibited pain, swelling, and cyanosis of the upper extremity, with worsening venous congestion on abduction of the arm. Five of six patients were originally treated for effort thrombosis of the subclavian vein with arm elevation and anticoagulation; two also underwent immediate thrombolytic therapy with urokinase. Venography was prompted in each case by positional symptoms during follow-up and showed irregular stenosis of the subclavian vein adjacent to the first rib. All patients underwent extended first rib resection and circumferential venolysis (one patient underwent bilateral procedures); one was performed through a transaxillary approach, two through a supraclavicular approach, and four through a new, "paraclavicular" approach. All subclavian veins appeared normal after venolysis. Five of six patients also underwent complete scalenectomy and brachial plexus neurolysis. In each patient, venous and neurogenic symptoms resolved and venography confirmed a patent subclavian vein, with follow-up ranging from 11 months to 13 years (mean 3.8 years).

Surgical recanalization of occluded peripheral arteries

This article, reflecting on the surgical recanalization of occluded peripheral arteries, has exposed the very essence of vascular surgery. Only the pioneering cardiac anomalies repaired by Gross (patent duct arteriosus, 1938), Blalock and Taussig (tetralogy of Fallot, 1944), and Crafoord and Nylin (coarctation, 1945) and the legendary aortic grafting operations of Oudot (occlusion, 1950) and Dubost and coworkers (aneurysm, 1951) are not a part of this article. The contributions to surgical recanalization of the occluded peripheral arteries are numerous. Some are well conceived, and others are innovative. Perhaps the most significant technique of all, endarterectomy itself, began purely as a serendipitous event. The startling impact of dos Santos' revolutionaly "disobliteration" was realized at once. Intimal injury during the operation did not cause inevitable thrombosis, as historically taught. Thus, all vascular interventions, either endarterectomy, graft repair, or the newer endovascular techniques discussed in this issue, would not have been developed without the understanding of the tolerance of the human intima to injury. Thromboendarterectomy, the basis of surgical recanalization of occluded arteries, unlocked the mystery of arterial rethrombosis after intervention. Recognizing these crucial facts, it will have a lasting place in the expanded discipline of vascular disease and its treatment. Dos Santos, the European founder of endarterectomy, and Wylie, the American pioneer and proponent of endarterectomy, were great friends in life (Fig. 4) and would certainly be pleased to see the further development of technology aimed at the treatment of atherosclerotic obstruction of the peripheral arteries.

Correlations between scores on a continuous performance test and parents' ratings of attention problems and impulsivity in children

This is a study of the relationship between a continuous performance test and parents' behavioral ratings of attention problems and impulsivity in 45 boys who had been referred to a clinic for learning and behavioral problems. No significant correlations obtained between these two methods of assessment. Perhaps the lack of congruence is due to the multidimensional nature of both attention problems and impulsivity. Suggestions for clinical practice and further research are discussed.

Heparin-mediated release of fibroblast growth factor-like activity into the circulation of rabbits

Fibroblast growth factors (FGFs) are a family of structurally related proteins that influence the growth and differentiation of a variety of cell types, including the cells of the vascular system. Due to the lack of signal sequence, basic FGF is not actively secreted. However, it has been detected in the extracellular matrix bound, at least in some cases, via heparin-like molecules. Heparin has been shown to displace FGF from cells and matrices in vitro, and we have investigated the possibility that a similar phenomenon might occur in vivo. Heparin was infused intravenously into anesthesized rabbits; plasma samples taken 30 min later and monitored using [3H]thymidine incorporation into BALB/c 3T3 cells were found to contain 3-fold more stimulatory activity than control plasma samples. Addition of heparin directly to the 3T3 cells or to the plasma samples following their collection did not affect the level of stimulatory activity. A time course of stimulatory activity in rabbit plasma following heparin administration revealed that 3T3 cell stimulatory activity rapidly increased following heparin infusion, peaked at 30 min, and declined to control levels by 90-120 min. The anticoagulant action of heparin followed a different time course, providing evidence that these two effects of heparin are functionally distinct. The binding affinity of the plasma-derived stimulatory activity for heparin was used to demonstrate that the activity is FGF-like in nature. Additionally, administration of [125I]bFGF to rabbits that had been "precleared" by heparin infusion resulted in an immediate peak of circulating labeled bFGF that decreased to plateau level by 20-45 min following injection.(ABSTRACT TRUNCATED AT 250 WORDS)

A daily radiation therapy record form

This communication reviews one institution's experience in developing a reliable and accurate radiation therapy record form. The design of a daily record is highly subjective. With the subjectivity of this process in mind, the purpose of this presentation is to describe the advantages of our form and to acquaint the reader with the literature useful in preparing a therapy record that fulfills their facility's requirements.

Stereotactic radiosurgery for fractionated radiation: a proposal applicable to linear accelerator and proton beam programs

A stereotactic radiosurgery technique is described which allows stereotactic radiation therapy to be easily fractionated on a daily or weekly basis. This permits adequate and safe radiation therapy to lesions larger than 2.5 cm, such as large arteriovenous malformations, and possibly safer radiation to smaller lesions near crucial intracranial structures. The technique utilizes external scalp landmarks and avoids the need for standard stereotactic head devices.

Rapid method for determination of isocenter of radiation gantry and alignment of laser beams for stereotactic radiosurgery

A simple technique has been designed which identifies the gantry isocenter and aligns the laser beams to the isocenter of the gantry within 3-5 min with an error of less than 0.75 mm, depending upon the accuracy of gantry rotation.

Seasonal distribution of live births in a rural community in the southern United States

"Births in Greene County, Alabama for the years 1980-1984 were examined and an overall seasonal trend was found with a peak from August through November. This trend was found to be most pronounced among women greater than 24 years old, and among multiparous women, and to be negatively correlated with seasonal variations in temperature and daylight. The phenomenon is likely multifactorial in origin, with sociocultural factors playing a considerable role. The influence of increasing maternal age and parity in the expression of the seasonal trend may be a function of age-related changes in families, with nuclear families acting as the most powerful potentiators of seasonality."

Branched nonreversed saphenous vein graft for complex renal artery stenosis

Use of recently developed instrumentation for venous valvotomy allows rapid construction of a branched, nonreversed saphenous vein graft. This technique was applied in a patient with renovascular hypertension and branch renal artery occlusive disease.

Arterial reconstruction at diverse sites using nonreversed autogenous vein. An application of venous valvulotomy

Improved instrumentation for venous valve extirpation has allowed rapid development of the in situ technique for femoral-tibial arterial reconstruction. Extension of this valvulotomy technique permits the expeditious construction of branched, nonreversed saphenous vein grafts for multiple vessel revascularization, and allows use of veins otherwise unsuitable in length for certain arterial bypass procedures. The nonreversed vein graft also appears to offer advantages over the reversed graft with regard to the size of the proximal and distal anastomoses when used as an aortorenal or iliorenal graft as well as in other anatomic locations. Over the past 30 months these techniques were used to implant 10 vein grafts at diverse sites in nine patients with initial success in all instances and one late graft failure.

Disseminated intravascular coagulation caused by abdominal aortic aneurysm

Disseminated intravascular coagulation (DIC) has been described as an occasional complication of abdominal aortic aneurysm. This is usually a perioperative coagulopathy, which may progress into a hemorrhagic diathesis. Rarely, DIC is present preoperatively as a result of the aneurysm itself. In the presence of additional pathophysiologic factors, a "compensated state" of secondary fibrinolysis may deteriorate into a clinically manifest coagulopathy. Heparin can be a useful adjunct in preoperative management of DIC, but definitive treatment requires surgical repair of the aneurysm. Long-term follow-up is essential to ensure that DIC is due to the aneurysm and that other disease processes are not overlooked. We report a case of DIC caused by an abdominal aortic aneurysm, with resolution after surgical treatment.

Bile peritonitis from a cholecystohepatic bile ductule: an unusual complication of cholecystectomy

A case is presented of postoperative bile peritonitis from an accessory cholecystohepatic bile ductule after cholecystectomy for acute cholecystitis. Accessory bile ductules (ducts of Luschka) are occasionally encountered in the gallbladder fossa but do not drain directly into the gallbladder fundus. Nevertheless, they may be injured during surgery and may go unrecognized. When recognized intraoperatively, ligation is acceptable; however, when they are actively leaking bile and are greater than 2 mm in diameter, repair of injured cholecystohepatic ducts may be indicated. This case serves to reemphasize one argument for the routine placement of drains after cholecystectomy for acute cholecystitis.

Intellectual, behavioral, and linguistic characteristics of three children with 18p- syndrome

Developmental characteristics of three girls with 18p- syndrome are described, with detailed history and results of psychological and speech/language evaluations completed at various ages. Results suggest that some children with 18p- syndrome have average abilities in selected areas, despite previous reports that these children have mild to severe mental retardation. Two of the three girls had more severe deficits in linguistic, as opposed to nonlinguistic, abilities. All had similar difficulties with speech articulation. It is suggested that children with speech/language delays who have physical features associated with this syndrome have chromosome analysis performed. It is also recommended that children identified as having 18p- syndrome be referred for comprehensive developmental assessments and remedial special education programming before a specific prognosis is determined.

A dose table describing fractions of peripheral volume for 125I volume implants

A dose table that provides the dose as a function of fractions of peripheral volume for 125I implants is presented. The table is based on seed distributions from 50 actual patient implants. Computer dosimetry was used to determine peripheral doses and dose ranges within implant volumes. The effects of seed distribution were also examined. The patient data and a study of computer-generated randomized seed coordinates within a given volume suggest that matched doses do not depend strongly on the exact position of each seed. The table provides the means for planning an implant to obtain a desired peripheral dose that can be directly compared with the postimplant computer dose calculation.