Expression and localization of vascular endothelial growth factor in normal abdominal aorta and abdominal aortic aneurysm

AIM

The genesis of abdominal aortic aneurysms is associated with remodeling of the vascular wall by angiogenesis as well as proteolysis. Vascular endothelial growth factor (VEGF) is known to be a regulator of angiogenesis and to simultaneously stimulate elastolytic proteinases. We analyzed the expression and localization of VEGF in human abdominal aortic aneurysms compared to normal human aorta

METHODS

Eighteen infrarenal aortic aneurysm samples were collected at the time of abdominal aortic aneurysm surgery, while nine normal aortic samples were obtained from autopsy specimens. Immunohistochemical staining was performed to detect VEGF. Immunoenzyme or immunofluorescent double staining was also used to identify those cells presenting VEGF.

RESULTS

VEGF was expressed in 18 (100%) of the 18 abdominal aortic aneurysm samples, while 0 (0%) in the 9 normal abdominal aorta samples. Of the 18 samples of aneurysms, all 18 displayed positive VEGF immunostaining in macrophages, 12 in smooth muscle cells (SMCs), and 9 in endothelial cells (ECs).

CONCLUSION

Our study clearly demonstrated the expression of VEGF in ECs, and SMCs, and macrophages of abdominal aortic aneurysms as well as its absence in those cells of normal abdominal aorta, suggesting that VEGF may play an important role in aneurysm formation via its direct and/or indirect actions.

Prostaglandin receptors EP2 and IP are detectable in atherosclerotic arteries and plaques

AIM

Prostaglandin (PG) receptor agonists are frequently used for the pharmacological treatment of arteriosclerosis obliterans (ASO). In particular, the PG receptors EP2 and IP stimulate vasodilation and inhibit platelet aggregation, biological processes thought to be protective against ASO and important for physiological homeostasis. However it is uncertain whether EP2 and IP exist in diseased arteries, or what their distribution within the artery might be. In this study, we analyzed the distribution of these PG receptors in patients with severe ASO to determine the potential application of stimulation of these receptors as targets for pharmacological treatment.

METHODS

We collected segments of atherosclerotic femoral arteries during femoropopliteal bypass surgery and determined the expression levels of EP2 and IP receptors by western blotting. Immunofluorescence was used to observe receptor localization.

RESULTS

Findings of western blotting showed an increased Cox-2 expression in patients with ASO. The EP2 as well as IP receptors were each induced approximately 3-fold in comparison to normal samples. The expression of these receptors was increased in the intimal layer as well as the medial layer; their expression was also detectable within the atherosclerotic plaque.

CONCLUSION

We observed induction of the PG receptors EP2 and IP in atherosclerotic femoral arteries in the arterial intima, medial layer, as well as the associated atherosclerotic plaque. These results suggest that receptor-selective PG agonists specifically target atherosclerotic arteries and therefore, may find potential application in the pharmacological management of patients with ASO.

Stent placement in the superficial femoral artery for patients on chronic hemodialysis with peripheral artery disease

AIM

Chronic hemodialysis is associated with a high prevalence of peripheral artery disease (PAD), and patients on chronic hemodialysis with PAD have an increased risk of critical limb ischemia. The present study assessed the hemodynamic and clinical outcomes of stent placement in the superficial femoral artery (SFA) for patients on chronic hemodialysis.

METHODS

Between February 2005 to August 2008, 43 consecutive lower limbs in 42 patients with SFA lesions that were successfully treated by primary stent placement were included in this study. Those were divided into a dialysis group (18 limbs) and a nondialysis group (25 limbs). Outcome measures included primary patency, assisted primary patency, limb salvage, and survival.

RESULTS

Patients were significantly younger and presented with significantly more symptomatic limb ischemia in the dialysis group compared to the nondialysis group, despite comparable TransAtlantic Inter-Society Consensus (TASC) classification scores of SFA lesions between the two groups. The primary patency, primary assisted patency, limb salvage, and survival rates of the dialysis group were similar to those of the nondialysis group.

CONCLUSIONS

Stent placement in the SFA is a feasible, safe, and effective procedure in patients on chronic hemodialysis with PAD, and may be offered as a first-choice therapeutic option for these patients.

Fate of varicose veins after great saphenous vein stripping alone

AIM

The aim of this study was to observe prospectively the clinical sequelae of varicose veins after great saphenous vein (GSV) stripping alone, and to examine whether spontaneous varicose vein regression or disappearance continued for a long period (>3 years).

METHODS

Thirty-nine consecutive patients (20 males and 19 females; mean age 57.2), who underwent GSV stripping in Fujita Health University (55 limbs) between November 1, 2002 and December 31, 2003 were enrolled.

RESULTS

At four to six weeks, varicose veins spontaneously resolved in 50 limbs (91%), in which subsequent sclerotherapy was not necessary. Five limbs subsequently underwent sclerotherapy for residual varicose veins (5%). At more than three years, 49 limbs (89%) completed the follow-up study. The recurrence after GSV stripping alone occurred in four of the 45 limbs (9%), while those of GSV stripping with sclerotherapy was one of the four limbs (25%).

CONCLUSIONS

This study definitely demonstrated that spontaneous varicose vein resolution can continue for more than three years after GSV stripping alone, suggesting that varicectomy can be deferred or avoided in many patients.

Hybrid surgical and endovascular therapy in multifocal peripheral TASC D lesions: up to three-year follow-up

AIM

The authors described their three-year experience with hybrid surgical and endovascular therapy for multifocal peripheral TASC D lesions, involving both the aortoiliac and/or superficial femoral and common femoral arteries.

METHODS

From February 2005 to March 2008, 21 lower limbs in 20 patients with multifocal peripheral artery disease, involving the aortoiliac and/or superficial femoral as well as common femoral arteries, were treated by hybrid surgical and endovascular therapy, such as aortoiliac and/or superficial femoral artery stenting as an adjunct to common femoral artery endarterectomy. Technical and hemodynamic success as well as primary and primary assisted patency and limb salvage rates were determined in concordance with the Society for Vascular Surgery guidelines.

RESULTS

All lower limbs successfully underwent successful hybrid surgical and endovascular therapy. The average ABPI before and after hybrid therapy significantly increased from 0.50 +/- 0.32 to 0.79 +/- 0.24 (P = 0.0022). The mean duration of follow-up was 357 days (range, 4 to 1400 days). Over all, the primary patency rates were 94%, 70% and 70% at 6, 12, and 24 months, respectively, and the primary assisted patency rates were 94% at 24 months. The limb salvage rate was 100% at 24 months. The survival rates were 95%, 88%, and 88% at 6, 12, and 24 months, respectively. The primary patency rate for intermittent claudication was significantly higher that that for critical limb ischemia, while no significant difference was found in the assisted primary patency and survival rates between intermittent claudication and critical limb ischemia.

CONCLUSION

Hybrid surgical and endovascular therapy, such as aortoiliac and/or superficial femoral artery stenting as an adjunct to common femoral artery endarterectomy, can provide a less invasive yet effective and durable option to patients with multifocal peripheral artery disease.

Protective effect of sivelestat sodium (Eraspol) on postoperative lung dysfunction in patients with type A acute aortic dissection: a pilot study

AIM

The authors evaluated the protective effect of sivelestat sodium on postoperative lung dysfunction in patients with type A acute aortic dissection who underwent aortic arch surgery with cardiopulmonary bypass (CPB) under deep hypothermia with circulatory arrest (DHCA).

METHODS

Twelve patients with type A acute aortic dissection who underwent aortic arch replacement under CPB with DHCA and were pretreated with or without sivelestat sodium (sivelestat group, N.=7 patients; control group, N.=5 patients) were observed. The ratio of arterial oxygen tension to inspired oxygen fraction (P/F ratio) was measured as a parameter of pulmonary function before and after operation. The number of white blood cells was also counted as an index of inflammatory reaction before and after the operation.

RESULTS

The P/F ratio decreased significantly after operation in the control group. However, the P/F ratio was unchanged between before and after operation in the sivelestat group. The number of white blood cells tended to increase after operation in the control group, whereas it decreased significantly after operation in the sivelestat group.

CONCLUSION

The present study demonstrated the protective effect of sivelestat sodium on postoperative lung injury in patients with acute type A aortic dissection undergoing aortic arch surgery under CPB with DHCA.

Relationship between parameters of air plethysmography and types of superficial venous reflux in patients with primary varicose veins

AIM

We investigated whether parameters of air plethysmography (APG) were correlated with types of superficial venous reflux as categorized by ascending venography in patients with primary varicose veins.

METHODS

Two hundred and eight limbs with primary varicose veins in 135 patients were evaluated by both APG and ascending venography. Venous hemodynamics was assessed with APG. The location of incompetent vein segments was determined based on the results of ascending venography.

RESULTS

Seventy-seven limbs had incompetence of the greater saphenous vein (GSV, G group), 36 had incompetence of the lesser saphenous vein (LSV, L group), and 77 had incompetence of the GSV and LSV (GL group). Twenty-five limbs did not have incompetence of the GSV or LSV (N group). The venous filling index (VFI) differed significantly between the N and the G and GL groups, the L group and the G and GL groups, and the G and GL groups. No significant difference was found between the N and L groups. The venous volume, ejection fraction, and residual volume fraction did not differ significantly among all four groups.

CONCLUSION

The VFI as measured by APG discriminates well between limbs with incompetence of the GSV and those without incompetence of the GSV or LSV, and between limbs with incompetence of the GSV and those with the LSV in patients with primary varicose veins, suggesting that the hemodynamic severity of superficial venous reflux progresses with involvement from the LSV to the GSV to both saphenous veins.

Laser Doppler skin perfusion pressure in the diagnosis of limb ischemia in patients with diabetes mellitus and/or hemodialysis

AIM

We investigated whether measurement of skin perfusion pressure (SPP), as measured by laser Doppler, can be used to evaluate the severity of limb ischemia in diabetes mellitus (DM) and/or hemodialysis (HD) patients.

METHODS

From April 2004 to March 2005, the ankle brachial pressure index (ABPI) and SPP were evaluated in 44 consecutive lower limbs with peripheral artery disease (PAD) and in 24 patients (21 males and 3 females, aged from 45 to 84 years, with a mean age of 69.3 years) with DM and/or HD. Twelve limbs were categorized as Fontaine stage II, 19 as Fontaine stage III and 24 as Fontaine stage IV.

RESULTS

The SPP did not differ significantly between limbs at Fontaine stage II and those at Fontaine stage III, but it was significantly lower in limbs at Fontaine stage IV than in those at Fontaine stage II or III. The ABPI did not differ significantly among limbs at Fontaine stages II, III and IV.

CONCLUSION

The SPP, as measured by the laser Doppler technique, may be used as a standard for classifying the severity of PAD in patients with DM and/or HD.

Intermediate-term results of angioscopy-assisted anterior valve sinus plication for primary deep venous insufficiency

AIM

The intermediate-term efficacy of angioscopy-assisted anterior valve sinus plication for primary deep venous insufficiency was evaluated.

METHODS

Twelve limbs in 11 patients had class 4 or higher disease on the SVS/ISCVS classification. Descending venography revealed grade-3 or 4-reflux in all limbs. The limbs were treated with angioscopy-assisted anterior valve sinus plication of the highest valve of the superficial femoral vein. Clinical evaluation and air plethysmography were performed at the final follow-up.

RESULTS

The mean follow-up was 38.4 months with a range of 24 to 48 months. Postoperative descending venography revealed significant improvement of the reflux of the superficial femoral vein. At the final follow-up, all patients reported relief of subjective symptoms. The ulcers healed and did not recur in the single limb with class-6 disease, the ulcers did not recur in four class-5 limbs, and there was a distinct clinical improvement with resolution of skin changes in the seven class-4 limbs. The venous filling index measured by air plethysmography was in a normal range in 8 of the 12 limbs.

CONCLUSIONS

Angioscopy-assisted anterior valve sinus plication may be a surgical technique that results in intermediate-term clinical and hemodynamic improvement in patients with primary deep venous insufficiency.

Relationship between air-plethysmographic venous function and clinical severity in primary varicose veins

AIM

The role of air plethysmography (APG) in the diagnosis of chronic venous insufficiency has not been well established. The purpose of this study was to elucidate the relationship between APG parameters and clinical severity in patients with chronic venous insufficiency.

METHODS

Two hundred and ninety-four limbs in 154 patients with primary varicose veins were evaluated by APG. Limbs were categorized according to the clinical classification of chronic venous disease suggested by the Ad Hoc Committee on Reporting Standards in Venous Disease of the North American Chapter of the Society for Vascular Surgery and International Society for Cardiovascular Surgery (SVS/ ISCVS).

RESULTS

The venous filling index (VFI) was significantly higher in classes 2, 3, 4, and 5+6 than in class 0 or 1, and did not differ among classes 2, 3, 4, 5+6. The ejection fraction did not differ significantly among the 6 classes, and the residual volume fraction was significantly higher in classes 2, 3, 5+6 than in class 0.

CONCLUSIONS

APG is a reasonable method for distinguishing the presence or absence of chronic venous insufficiency, but it cannot discriminate the clinical severity. Among APG parameters, the VFI is the most useful diagnostic parameter in the evaluation of chronic venous insufficiency.

Presence of prostacyclin receptor in arteriosclerotic human femoral artery

AIM

Prostacyclin, which is mainly synthesized by vascular endothelial cells, exerts antiplatelet and smooth-muscle-relaxant effects, thereby maintaining cardiovascular homeostasis. Prostacyclin analogues have been clinically proven to improve ischemic symptoms and prevent the occurrence of vascular events in the lower extremities of patients with arteriosclerosis obliterans. We examined the presence of prostacyclin receptor (IP receptor) in an arteriosclerotic human femoral artery.

METHODS

Specimens of the femoral artery were obtained at the time of limb amputation from an 83-year-old woman. Atherosclerotic lesions and associated changes such as calcification were evident. The specimens were stained with hematoxylin and eosin, and processed for immunohistochemistry.

RESULTS

A monolayer of cells was observed on the luminal side of the femoral artery. Single immunohistochemistry showed the presence of the IP receptors on cells of the luminal side of the femoral artery. Triple-immunofluorescence staining revealed colocalization of IP-receptor-positive cells and cells positive for von Willebrand factor, a marker of vascular endothelial cells.

CONCLUSIONS

We investigated the presence of the IP receptor in the human femoral artery immunohistochemically, and demonstrated their strong expression in endothelial cells. This finding suggests that prostacyclin or prostacyclin analogues may act on their receptors on endothelial cells in patients with arteriosclerosis obliterans.

Aneurysmal expansion of the visceral patch after thoracoabdominal aortic replacement: an argument for limiting patch size?

INTRODUCTION

Thoracoabdominal aortic replacement requires visceral vessel revascularization and is usually performed with Crawford's inclusion technique or a large Carrel patch. This segment of retained native aorta may be prone to recurrent aneurysmal disease. We reviewed our experience with patients in whom aneurysmal expansion of the visceral patch was detected.

METHODS

The records of 107 patients undergoing thoracoabdominal aortic replacement operations performed or followed up at the Johns Hopkins Hospital between 1992 and 2000 were reviewed. All patients had visceral patches created for type II, III, or IV aneurysms. Visceral patches were considered aneurysmal if the maximal diameter of the aortic prosthesis and patch was 4.0 cm or more.

RESULTS

Patch aneurysmal expansion (mean, 5.4 cm) was detected in eight patients (7.5%). All three women had connective tissue disorders (mean age, 36 years), and all five men had atherosclerotic disease (mean age, 73 years). Five patients were symptom free with their aneurysms detected by surveillance computed tomography scans; two patients had back pain prompting computed tomography scans; and one patient presented with an emergency patch rupture. Aneurysmal patches were successfully revised in three patients. Two patients died in the operating room, and three patch aneurysms (< 5 cm) are still being observed. The mean time to the detection of aneurysmal expansion was 6.5 years after the original operation. Therapy consisted of replacement of a segment of the thoracoabdominal aortic graft and refashioning a smaller patch, including only the visceral artery orifices with separate attachment of the left and possibly right renal artery.

CONCLUSIONS

Although Crawford's inclusion method of visceral patch construction is generally durable, patients undergoing thoracoabdominal aortic replacement require yearly surveillance for the detection of aneurysmal expansion of the visceral patch. We recommend limiting visceral patch size at the original operation by routinely excluding the orifice of the left renal artery. Patients at high risk for recurrent aneurysmal expansion, such as those with connective tissue disorders, will benefit from creating small visceral patches and possibly implanting both renal arteries separately during the original operation.

Improved quality of life among patients with symptomatic carotid artery disease undergoing carotid endarterectomy

BACKGROUND

Few studies have examined how carotid endarterectomy affects patients' view of their quality of life.

METHODS

Patients undergoing carotid endarterectomy from January 1996 to March 1997 at the John Radcliffe Hospital completed the United Kingdom Short Form 36 (SF-36) Health Survey Questionnaire before undergoing the procedure and again at 3 months afterward. Scores were compared with population normal values.

RESULTS

In 50 patients with symptomatic carotid artery disease, there was significant improvement in the SF-36 overall "change in health" score after the procedure compared with beforehand (61.0 +/- 3.7 vs 44.5 +/- 3.4, P =.003, Wilcoxon signed rank test). There were, however, no statistically significant differences in the group's mean SF-36 subscores after operation compared with before the procedure. The physical subscores were below age-adjusted healthy population means but similar to those for chronically ill patients (physical function subscore P =.015 vs normal, P =.89 vs ill; role limitation-physical subscore P =.007 vs normal, P =.89 vs ill). Patients with postoperative complications did not have an improved change in health score (-12.5 vs 22.0, P =.03, Mann-Whitney U test). There was no effect on change in health score because of other risk factors or in patients with contralateral carotid artery occlusion or a history of preoperative stroke.

CONCLUSIONS

Patients with symptomatic carotid artery disease undergoing an uncomplicated carotid endarterectomy perceive improved quality of life and overall health. There is no perception of worsened pain, energy, or physical or mental function after the procedure. These results confirm that patients believe that performance of carotid endarterectomy improves their overall health, supporting the surgical approach to carotid artery disease.

Impact of race on the outcome of carotid endarterectomy: a population-based analysis of 9,842 recent elective procedures

OBJECTIVE

To examine the influence of race and other potentially confounding variables on the outcome of carotid endarterectomy (CEA).

SUMMARY

Previous studies have demonstrated that CEA is performed less frequently in black patients, although little attention has been focused on the influence of race on the outcome of surgery.

METHODS

The Maryland Health Services Cost Review Commission database was reviewed to identify all elective CEA procedures performed in all nonfederal acute care hospitals in the state from 1990 through 1995 to examine the influence of race and other factors on the rates of in-hospital complications, in-hospital stroke, length of stay, and total hospital charges.

RESULTS

Carotid endarterectomy was performed in 9,219 (94%) white and 623 (6%) black patients during this period. The in-hospital stroke rate was 1.7%-3. 1% among black patients and 1.6% among white patients. Black patients had a longer length of stay and higher mean hospital charges than white patients. Multivariate logistic regression analysis identified black race as an independent risk factor for in-hospital stroke. Performance of CEA by a high-volume surgeon was protective for the combined occurrence of in-hospital stroke or death, and whites were more than twice as likely to undergo surgery performed by high-volume surgeons. Conversely, undergoing surgery in a low-volume hospital was associated with in-hospital stroke, and blacks were four times as likely to use low-volume hospitals.

CONCLUSIONS

Black patients who underwent elective CEA in Maryland from 1990 to 1995 had an increased incidence of in-hospital stroke, a longer hospital stay, and higher hospital charges than whites. Black race was identified as an independent risk factor for in-hospital stroke, although the reasons for this influence of race on outcome are undefined. The authors' observations also suggest the possibility of limited access to optimal surgical care among blacks, and this issue warrants further study.

Accurate placement of microvascular guide sutures

A simple technique to accurately place initial microvascular guide sutures is described. Enhanced suture placement enables anastomosis construction in situations in which the clamp must be placed very close to the vessel end or if the vessel lumen is distorted or poorly visualized. Because this technique eliminates the need for retraction on the guide suture tails, it is particularly useful for solo microvascular surgeons.

Acute abdomen with colonic necrosis induced by Kayexalate-sorbitol

Colonic necrosis is an unusual complication after treatment of hyperkalemia with sodium polystyrene sulfonate (SPS, Kayexalate) in sorbitol. To increase awareness of this complication, we report a case of necrosis of the transverse colon in a patient given oral and rectal SPS-sorbitol for hyperkalemia. Colonic necrosis was manifested as an acute abdomen within 24 hours of initial administration. Prompt surgical resection of the necrotic transverse colon permitted rapid recovery of bowel function. Although SPS crystals are seen microscopically in the necrotic bowel, experimental evidence implicates the sorbitol component of the SPS-sorbitol in the pathogenesis of colonic necrosis. A high index of suspicion for the unusual complication of colonic necrosis after oral or rectal administration of SPS-sorbitol may allow prompt recognition and surgical cure.

Results of elective abdominal aortic aneurysm repair in the 1990s: A population-based analysis of 2335 cases

OBJECTIVE

The safety and efficacy of conventional abdominal aortic aneurysm (AAA) repair are undergoing increased examination in parallel with the development of less invasive repair methods. Because most published studies of elective AAA repair report operations performed in tertiary referral institutions and thus may not reflect the outcome in the surgical community at large, the current population-based study was undertaken to document the results obtained across a broad spectrum of clinical practice in a defined geographic area and to examine the factors that influence the outcomes.

METHODS

The Maryland Health Services Cost Review Commission database was used to identify all the elective AAA repairs that were performed in all the nonfederal acute care hospitals in the state from 1990 to 1995.

RESULTS

Elective AAA repair was performed on 2335 patients (mean age, 70.4 years) in 46 of the 52 (88%) nonfederal acute care hospitals in the state, including seven high-volume (>100 cases), nine moderate-volume (50 to 99 cases), and 30 low-volume (<50 cases) institutions. The in-hospital mortality rate was 3.5% and increased significantly with advancing age: less than 65 years, 2.2%; 65 to 69 years, 2.5%; 70 to 79 years, 3.5%; and more than 80 years, 7.3% (P =.002). Mortality rates were higher for women (4.5% vs 3.2%; P =.17), for blacks (6.7% vs 3.2%; P =.046), and for patients with renal failure (11.8% vs 3. 4%; P =.11) but not for patients with hypertension, diabetes, heart disease, and pulmonary disease. The operative mortality rate was inversely correlated with hospital volume (4.3% in low-volume hospitals, 4.2% in moderate-volume hospitals, and 2.5% in high-volume hospitals; P =.08), although no differences were noted in the mean ages or comorbidity levels of patients who underwent operations in these three hospital populations. The operative mortality rate was inversely correlated with the experience of the individual surgeon: one case, 9.9%; two to nine cases, 4.9%; 10 to 49 cases, 2.8%; 50 to 99 cases, 2.9%; and more than 100 cases, 3.8% (P =.01). Multivariate analysis results identified patient age (P =. 002), low hospital volume (P =.039), and very low surgeon volume (P =.01) as independent predictors of operative mortality. The mean length of stay and mean hospital charges were 10.6 days and $17,589 and decreased with increasing surgeon volume: one case, 22.7 days/$32,800; two to nine cases, 10.6 days/$18,509; 10 to 49 cases, 10.0 days/$16,611; 50 to 99 cases, 10.9 days/$17,843; and more than 100 cases, 9.6 days/$16,682 (P <.0001/P <.0001).

CONCLUSION

Elective AAA repair is a safe procedure in contemporary practice in Maryland. Operative risk is increased among the elderly and when operations are performed by surgeons with very low volumes or in low-volume hospitals. Hospital lengths of stay were shorter and charges were lower when elective AAA repair was performed by surgeons with higher volumes.

Neutralizing TGF-beta1 antibody infusion in neonatal rat delays in vivo glomerular capillary formation 1

BACKGROUND

The interruption of transforming growth factor-beta (TGF-beta) signaling with dominant negative type II TGF-beta receptors in bovine glomerular endothelial cells abrogates capillary morphogenesis in vitro, and genetic defects in the TGF-beta1 signaling cascade in mice and humans result in abnormalities of blood vessel morphology. This study sought to determine whether TGF-beta1 participates in renal glomerular capillary development in vivo.

METHODS

To inhibit TGF-beta1 action, neutralizing anti-TGF-beta1 IgG was infused intra-arterially into the suprarenal aorta of three-day-old rats, and the glomerular endothelial cell appearance was evaluated two days later by immunohistochemical detection of the endothelium-specific von Willebrand factor, in situ analysis of vascular endothelial growth factor receptor binding, and morphometric study of developing glomerular structures by transmission electron microscopy.

RESULTS

The infusion of neutralizing the TGF-beta1 antibody markedly reduced the invasion of comma- and S-shaped bodies by endothelial cells, and inhibited organization of endothelial cells into capillaries in these structures. In addition, capillary lumen formation and endothelial cell fenestration in developing cortical, but not in deep, already mature glomeruli were inhibited by neutralizing TGF-beta1 antibody. Seven days after TGF-beta1 antibody infusion, glomeruli appeared normal, and no reduction in glomerular number was observed.

CONCLUSIONS

These findings suggest that TGF-beta1 plays a critical role in the formation of glomerular capillaries during renal development in the rat, and that flattening and fenestration of glomerular capillaries require the action of TGF-beta1.

Chronic in vitro shear stress stimulates endothelial cell retention on prosthetic vascular grafts and reduces subsequent in vivo neointimal thickness

OBJECTIVE

The absence of endothelial cells at the luminal surface of a prosthetic vascular graft potentiates thrombosis and neointimal hyperplasia, which are common causes of graft failure in humans. This study tested the hypothesis that pretreatment with chronic in vitro shear stress enhances subsequent endothelial cell retention on vascular grafts implanted in vivo.

METHODS

Cultured endothelial cells derived from Fischer 344 rat aorta were seeded onto the luminal surface of 1.5-mm internal diameter polyurethane vascular grafts. The seeded grafts were treated for 3 days with 1 dyne/cm2 shear stress and then for an additional 3 days with 1 or 25 dyne/cm2 shear stress in vitro. The grafts then were implanted as aortic interposition grafts into syngeneic rats in vivo. Grafts that were similarly seeded with endothelial cells but not treated with shear stress and grafts that were not seeded with endothelial cells served as controls. The surgical hemostasis time was monitored. Endothelial cell identity, density, and graft patency rate were evaluated 24 hours after implantation. Endothelial cell identity in vivo was confirmed with cells transduced in vitro with beta-galactosidase complementary DNA in a replication-deficient adenoviral vector. Histologic, scanning electron microscopic, and immunohistochemical analyses were performed 1 week and 3 months after implantation to establish cell identity and to measure neointimal thickness.

RESULTS

The pretreatment with 25 dyne/cm2 but not with 0 or 1 dyne/cm2 shear stress resulted in the retention of fully confluent endothelial cell monolayers on the grafts 24 hours after implantation in vivo. Retention of seeded endothelial cells was confirmed by the observation that beta-galactosidase transduced cells were retained as a monolayer 24 hours after implantation in vivo. In the grafts with adherent endothelial cells that were pretreated with shear stress, immediate graft thrombosis was inhibited and surgical hemostasis time was significantly prolonged. Confluent intimal endothelial cell monolayers also were present 1 week and 3 months after implantation. However, 1 week after implantation, macrophage infiltration was observed beneath the luminal cell monolayer. Three months after the implantation in vivo, subendothelial neointimal cells that contained alpha-smooth muscle actin were present. The thickness of this neointima averaged 41 +/- 12 micrometer and 60 +/- 23 micrometer in endothelial cell-seeded grafts that were pretreated with 25 dyne/cm2 shear stress and 1 dyne/cm2 shear stress, respectively, and 158 +/- 46 micrometer in grafts that were not seeded with endothelial cells.

CONCLUSION

The effect of chronic shear stress on the enhancement of endothelial cell retention in vitro can be exploited to fully endothelialize synthetic vascular grafts, which reduces immediate in vivo graft thrombosis and subsequent neointimal thickness.

Shear stress and the endothelium

Shear stress and the endothelium. Vascular endothelial cells (ECs) in vivo are influenced by two distinct hemodynamic forces: cyclical strain due to vessel wall distention by transmural pressure, and shear stress, the frictional force generated by blood flow. Shear stress acts at the apical cell surface to deform cells in the direction of blood flow; wall distention tends to deform cells in all directions. The shear stress response differs, at least partly, from the cyclical strain response, suggesting that cytoskeletal strain alone cannot explain it. Acute shear stress in vitro elicits rapid cytoskeletal remodeling and activates signaling cascades in ECs, with the consequent acute release of nitric oxide and prostacyclin; activation of transcription factors nuclear factor (NF)kappaB, c-fos, c-jun and SP-1; and transcriptional activation of genes, including ICAM-1, MCP-1, tissue factor, platelet-derived growth factor-B (PDGF-B), transforming growth factor (TGF)-beta1, cyclooxygenase-II, and endothelial nitric oxide synthase (eNOS). This response thus shares similarities with EC responses to inflammatory cytokines. In contrast, ECs adapt to chronic shear stress by structural remodeling and flattening to minimize shear stress. Such cells become very adherent to their substratum and show evidence of differentiation. Increased adhesion following chronic shear stress has been exploited to generate vascular grafts with confluent EC monolayers, retained after implantation in vivo, thus overcoming a major obstacle to endothelialization of vascular prostheses.

Surgical repair of ruptured abdominal aortic aneurysms in the state of Maryland: factors influencing outcome among 527 recent cases

PURPOSE

Abdominal aortic aneurysm (AAA) rupture has been historically associated with high operative mortality rates. In this community-based, cross-sectional study, we examined factors influencing outcome after operations performed for ruptured AAA (rAAA).

METHODS

An analysis of a state database identified 3820 patients who underwent AAA repair between 1990 and 1995, including 527 (13.8%) who had an operation for an rAAA. Demographic variables examined included patient age, gender, race, associated comorbidity rates, operative surgeon experience with rAAA, and annual hospital rAAA and total AAA operative volumes. Outcomes measured included operative mortality rates, hospital length of stay, and charges.

RESULTS

Operative mortality rates increased significantly with advancing age (P < 0.0001) but were not related to gender (P = 0.474) or race (p = 0.598) and were significantly lower among patients with hypertension (P = 0.006) or pulmonary disease (P = 0.045). There was no relationship between hospital rAAA or total AAA volume and rAAA repair mortality rate, although high-volume surgeons (i.e., performing more than 10 rAAA repairs) had decreased mortality rates and hospital charges compared with other surgeons. Hospital lengths of stay and charges increased with age among survivors, but not nonsurvivors, of rAAA repair. Despite a stable incidence of rAAA repairs during the study interval and no significant change in the mean age of patients undergoing operation or the percentage of operations performed by high-volume surgeons, the statewide mortality rate declined from 59.3% to 43.2% (P = 0.039).

CONCLUSION

The incidence of rAAA does not appear to be declining. Although operative rAAA repair continues to be associated with substantial risk and remains an especially lethal condition among the elderly, the operative mortality rate has declined in recent years in Maryland. Lower operative mortality rates and hospital charges are associated with operations performed by high-volume surgeons.

Successful delayed bilateral renal revascularization during active phase of Takayasu's arteritis

Successful bilateral renal revascularization was performed 24 days after the development of angiotensin converting enzyme-inhibitor-induced bilateral renal artery thrombosis and anuric acute renal failure in a patient with Takayasu's arteritis. Excellent results were obtained after an unusually long ischemic time for a patient with active-phase disease. The outcome suggests that aggressive surgical revascularization can benefit patients with renal failure caused by renal arterial occlusion during the active phase of Takayasu's arteritis.

Influence of age and hospital volume on the results of carotid endarterectomy: a statewide analysis of 9918 cases

PURPOSE

This study evaluated the impact of patient age and hospital volume on the results of carotid endarterectomy (CEA) in contemporary practice.

METHODS

The Maryland Health Services Cost Review Commission (MHSCRC) database was reviewed to identify all patients who underwent elective CEA as the primary procedure in all acute care hospitals in the state over the past 6 years.

RESULTS

From January 1990 through December 1995, 9918 elective CEAs were performed in 48 hospitals at a total charge of $68.9 million. Postoperative death and neurologic complications occurred in 90 (0.9%) and 166 (1.7%) cases, including 0.8% and 1.7%, 0.9% and 1.6%, 0.9% and 1.8%, and 1.4% and 1.3% of patients < 65 years, 65 to 69 years, 70 to 79 years, and > or = 80 years old, respectively. The mean length of stay and hospital charges increased linearly with increasing age: 4.2 days/$6550, 4.4 days/$6834, 4.8 days/$7059, and 5.6 days (p < 0.0001 vs others)/$7756 (p < 0.005 vs 70 to 79 years and p < 0.0003 vs < 70 years old), respectively, for patients < 65, 65 to 69, 70 to 79, and > or = 80 years old. The mortality rate was 1.9% in low-volume hospitals, 1.1% in moderate-volume hospitals, and 0.8% in high-volume hospitals. The neurologic complication rate was significantly higher (6.1%; p < 0.0001) in low-volume when compared with moderate-volume (1.3%) and high-volume (1.8%) hospitals.

CONCLUSIONS

CEA is a safe procedure in the majority of hospitals in contemporary practice, even among the very elderly, who may experience a longer length of stay and higher charges correlating with their documented greater medical complexity.

Vena cava filter ensnarement and delayed migration: an unusual series of cases

PURPOSE

To review delayed and guidewire-induced morbidity associated with vena cava filters.

METHODS

The records from the Johns Hopkins Hospital, a tertiary care referral center, of all patients who had vena cava filter complications from August 1993 through July 1996 were retrospectively reviewed.

RESULTS

Five patients had filter migration or ensnarement with a guidewire. One patient had delayed extrusion of a filter strut into the duodenum. Four patients had filters ensnared by guidewires, including one during initial filter placement and one several years after placement.

CONCLUSIONS

Delayed complications of vena cava filters should be considered whenever unusual patient signs or symptoms cannot be easily explained, even in the absence of a history of filter placement. To prevent guidewire ensnarement of filters, simple techniques should modify endovascular procedures when vena cava filters are present.