Use of water- and land-based gait training to improve walking capacity in adults with complete spinal cord injury: A pilot study

OBJECTIVE

Little is known regarding the extent to which mobility can be improved using gait-based therapies in individuals with complete spinal cord injury (cSCI). Against this backdrop, the purpose of our study was to document changes in walking capacity following an extended period of underwater treadmill training (UTT) and supplemental overground walk training (OWT) in persons with cSCI.

DESIGN

Longitudinal design.

SETTING

University research center.

PARTICIPANTS

Five adults (mean age = 41.2 ± 5.9 years) with motor-complete (AIS A), chronic (mean years post-injury = 3.2 ± 1.6 years) cSCI who had not received epidural spinal cord stimulation (eSCS).

INTERVENTION

Participants underwent one year of UTT (3 walking bouts per day; 2-3 days per week). Once independent stepping activity in the water was observed, OWT, as tolerated, was performed prior to UTT.

OUTCOME MEASURE

Walking capacity was evaluated using the Walking Index for Spinal Cord Injury (WISCI-II) prior to UTT (Time 1: T1), six months after the start of UTT (Time 2: T2), and following completion of UTT (Time 3: T3).

RESULTS

Non-parametric analyses revealed a significant time effect (P < .05) for WISCI-II. Pre-planned comparisons revealed no difference in WISCI-II levels measured at T1 (0.20 ± 0.45) and T2 (4.80 ± 4.55) and at T2 (4.80 ± 4.55) and T3 (8.40 ± 1.34). However, the WISCI-II level obtained at T3 (8.40 ± 1.34) was significantly higher compared to the T1 value.

CONCLUSION

Our preliminary findings demonstrate that in the absence of eSCS, combined UTT and supplemental OWT can improve functional walking capacity in adults with cSCI.

Functional Movement Screen Items Predict Dynamic Balance Under Military Torso Load

INTRODUCTION

Musculoskeletal injuries threaten military readiness and impose a significant financial burden. The functional movement screen (FMS), a 7-item, preparticipation screening tool, may aid in identifying compensatory movement patterns that can hinder physical performance and lead to injuries in active-duty military personnel. The primary aim of our study was to determine if items scores from the traditional FMS or a modified FMS (mFMS) obtained under loaded conditions can predict dynamic balance scores while wearing a military load.

MATERIALS AND METHODS

Thirty physically active adults (19 males and 11 females) who qualified for Army basic training completed unloaded and loaded FMS testing. Loaded balance was assessed using the Y balance test and the Biodex balance system. The mFMS and both loaded balance assessment protocols included a military load consisting of a standard issue rucksack (M.O.L.L.E.), kevlar helmet, and weighted vest (mass = 24.2 kg).

RESULTS

mFMS item scores were significantly lower than FMS scores for six of the seven movement items. Both FMS and mFMS composite scores were correlated with Y balance scores (FMS: r = 0.53, P = 0.003; mFMS: r = 0.37, P = 0.043). Participants with higher composite scores (≥15) outperformed those with lower composite scores (≤14) for the FMS (P =0.006, d = 1.16) and mFMS (P = 0.031, d = 0.75). Lasso penalized regression analyses revealed that (1) higher unloaded in-line lunge subscores predicted better Y balance scores, (2) loaded trunk stability push-up scores of three predicted worse balance on the Biodex, and (3) unloaded and loaded shoulder mobility scores of 3 predicted better performance on the Biodex balance system.

CONCLUSIONS

The in-line lunge subscore from the FMS was the strongest predictor of torso-loaded balance, and the FMS may be more appropriate than a torso-loaded FMS battery when predicting torso-loaded balance among adults with body composition and fitness profiles similar to those of entering military recruits. These findings provide evidence supporting the use of the conventional FMS to identify active-duty personnel who exhibit greater balance deficits and may develop related musculoskeletal injuries while performing operational tasks that require the transport of heavy loads over long distances.

Use of Functional Movement Screen Scores to Predict Dynamic Balance in Physically Active Men and Women

Scudamore, EM, Stevens, SL, Fuller, DK, Coons, JM, and Morgan, DW. Use of functional movement screen scores to predict dynamic balance in physically active men and women. J Strength Cond Res 33(7): 1848-1854, 2019-The primary focus of this study was to determine whether scores obtained from the Functional Movement Screen (FMS) can predict dynamic balance in young, healthy adults. Thirty-four physically active participants completed the FMS, and balance was assessed using measures of composite reach (CR) distance and overall stability indices (OSI) derived from Y Balance and Biodex Balance System testing, respectively. Results indicated that higher overall FMS scores were associated with better CR and OSI, and participants with FMS composite scores greater than 14 exhibited better CR compared to those with composite scores less than or equal to 14. In addition, lasso penalized regression demonstrated that (a) scores of 2 on the deep squat and 3 on the trunk stability push-up movements predicted a greater CR and (b) higher shoulder mobility scores and a rotary stability score of 3 predicted better OSI. We conclude that dynamic balance in young, active men and women can be predicted by specific FMS item scores.

Ambulation and physical function after eccentric resistance training in adults with incomplete spinal cord injury: A feasibility study

Background: Strengthening the lower extremities has shown to positively influence walking mechanics in those with neurological deficiencies. Eccentric resistance training (ERT) is a potent stimulus for the development of muscular strength with low metabolic demand. Thereby, ERT may benefit those with incomplete spinal cord injuries (iSCI) seeking to improve ambulatory capacity. Design: This study was aimed to determine the effect of ERT on walking speed, mobility, independence, and at home function following iSCI. Methods: Individuals with longstanding iSCI trained twice a week for 12 weeks on an eccentrically biased recumbent stepper. Outcome measures: Walking speed (10 meter walk test; 10MWT), mobility (timed up and go), independence (Walking Index for Spinal Cord Injury; WISCI), and at home function (Spinal Cord Independence Measure; SCIM) were assessed at baseline, after 6 weeks, and after 12 weeks of ERT. Results: There were improvements in walking mobility (158.36 + 165.84 seconds to 56.31 + 42.42 seconds, P = .034, d = 0.62), speed (0.34 + 0.42  m/s to 0.43 + 0.50  m/s, P = .005, d = .23), and independence (8 + 7 to 13 + 7, P = .004, d = .73) after 12 weeks of ERT. At home function remained unchanged (22 + 10 to 24 + 10, P = .10, d = .12). Conclusions: Improving lower extremity strength translated to walking performance and independence in those with iSCI. Additionally, ERT may diminish therapist burden in programs designed to improve ambulatory capacity or strength in those with iSCI.

Strength and Step Activity After Eccentric Resistance Training in Those With Incomplete Spinal Cord Injuries

Background: Individuals with spinal cord injuries (SCIs) often experience general weakness in the lower extremities that undermines daily step activity. Objective: To investigate the efficacy of eccentrically biased resistance training on lower extremity strength and physical activity of individuals with spinal injuries. Methods: Individuals with long-standing incomplete SCIs (N = 11) capable of completing a 10-meter walk assessment were included. All participants who completed the familiarization period finished the training. Individuals trained two times per week for 12 weeks on a lower body eccentric resistance training machine. It was hypothesized that the outcome variables (eccentric strength, isometric strength, and daily step physical activity) would improve as a result of the training intervention. Results: Eccentric strength [F(1.27, 12.71) = 8.42, MSE = 1738.35, H-F p = .009] and isometric strength [F(1.97, 19.77) = 7.10, MSE = 11.29, H-F p = .005] improved as a result of the training while daily step activity remained unchanged [F(2.00, 18.00) = 2.73, MSE = 216,836.78, H-F p = .092]. Conclusions: Eccentric resistance training improves eccentric and isometric strength. These physiological adaptations may translate to improved gait mechanics, but further study is required to identify this potential crossover effect.

Heart rate response during underwater treadmill training in adults with incomplete spinal cord injury

BACKGROUND

Walking on a submerged treadmill can improve mobility in persons displaying lower limb muscle weakness and balance deficits. Little is known, however, regarding the effect of water treadmill exercise on cardiac performance in persons with incomplete spinal cord injury (iSCI).

OBJECTIVE

To assess heart rate response during underwater treadmill training (UTT) in adults with iSCI.

METHODS

Seven males and 4 females with iSCI (age = 48 ± 13 years; 5 ± 8 years after injury) completed 8 weeks of UTT (3 sessions per week; 3 walks per session) incorporating individually determined walking speeds, personalized levels of body weight unloading, and gradual, alternating increases in speed and duration. Heart rate was monitored during the last 15 seconds of the final 2 minutes of each walk.

RESULTS

Over the course of 3 biweekly periods in which walking speed remained constant, heart rate fell by 7% (7 ± 1 b•min(-1); P < .001) in weeks 2 and 3, 14% (17 ± 6 b•min(-1); P < .001) in weeks 4 and 5, and 17% (21 ± 11 b•min(-1); P < .001) in weeks 6 and 7.

CONCLUSION

In adults with iSCI, progressively greater absolute and relative reductions in submaximal exercise heart rate occurred after 2 months of UTT featuring a systematic increase in training volume.

Effects of underwater treadmill training on leg strength, balance, and walking performance in adults with incomplete spinal cord injury

OBJECTIVE

To document the effects of underwater treadmill training (UTT) on leg strength, balance, and walking performance in adults with incomplete spinal cord injury (iSCI).

DESIGN

Pre-test and post-test design.

SETTING

Exercise physiology laboratory.

PARTICIPANTS

Adult volunteers with iSCI (n = 11).

INTERVENTION

Participants completed 8 weeks (3 × /week) of UTT. Each training session consisted of three walks performed at a personalized speed, with adequate rest between walks. Body weight support remained constant for each participant and ranged from 29 to 47% of land body weight. Increases in walking speed and duration were staggered and imposed in a gradual and systematic fashion.

OUTCOME MEASURES

Lower-extremity strength (LS), balance (BL), preferred and rapid walking speeds (PWS and RWS), 6-minute walk distance (6MWD), and daily step activity (DSA).

RESULTS

Significant (P < 0.05) increases were observed in LS (13.1 ± 3.1 to 20.6 ± 5.1 N·kg(-1)), BL (23 ± 11 to 32 ± 13), PWS (0.41 ± 0.27 to 0.55 ± 0.28 m·s(-1)), RWS (0.44 ± 0.31 to 0.71 ± 0.40 m·s(-1)), 6MWD (97 ± 80 to 177 ± 122 m), and DSA (593 ± 782 to 1310 ± 1258 steps) following UTT.

CONCLUSION

Physical function and walking ability were improved in adults with iSCI following a structured program of UTT featuring individualized levels of body weight support and carefully staged increases in speed and duration. From a clinical perspective, these findings highlight the potential of UTT in persons with physical disabilities and diseases that would benefit from weight-supported exercise.

Leg strength, preferred walking speed, and daily step activity in adults with incomplete spinal cord injuries

BACKGROUND

The reduction in physical activity that accompanies spinal cord injury (SCI) contributes to the development of secondary health concerns. Research has explored potential strategies to enhance the recovery of walking and lessen the impact of physical disability following SCI, but further work is needed to identify determinants of community walking activity in this population.

OBJECTIVES

To quantify relationships among lower extremity strength (LES), preferred walking speed (PWS), and daily step activity (DSA) in adults with incomplete SCI (iSCI) and determine the extent to which LES and PWS predict DSA in persons with iSCI.

METHODS

Participants were 21 adults (age range, 21 to 62 years; AIS levels C and D) with iSCI. Maximal values of hip abduction, flexion, and extension, knee flexion and extension, and ankle dorsiflexion and plantar flexion were measured using handheld dynamometry and were summed to determine LES. PWS was calculated using a photoelectric cell-based timing system, and participants were fitted with activity monitors to measure DSA in a natural setting.

RESULTS

Statistically significant (P <; .05) correlations of moderate to high magnitude (.74 to .87) were observed among LES, PWS, and DSA. Multiple regression analysis revealed that LES and PWS accounted for 83% (adjusted R2) of the variation in DSA (P <; .001).

CONCLUSION

A significant proportion of the explained variance in DSA can be predicted from knowledge of LES and PWS in adults with iSCI. These findings suggest that future efforts to improve community walking behavior following SCI should be directed toward increasing LES and PWS.

Toll-like receptors and tolerance to ischaemic injury in the brain

Ischaemic tolerance in the brain is a powerful adaptive defence that involves an endogenous programme of neuroprotection culminating in marked protection against brain injury from ischaemia. A range of preconditioning stimuli exist that differ in ligand and target characteristics but share the common feature of causing mild stress or insult without inducing overt injury. The protective phenotype that emerges confers tolerance to subsequent exposure to injurious insults. Tolerance to injury is the result of genomic reprogramming, an adaptation comprising regulatory processes that countermand injurious effectors and invoke novel neuroprotective pathways. TLRs (Toll-like receptors) play important roles in sensing potential danger/insult in the form of pathogens as well as endogenous stress molecules that occur in response to mild injury (e.g. heat-shock proteins). Recent studies suggest that TLRs are novel and potent preconditioning targets that offer substantial promise to protect the brain from ischaemic injury.

The impact of training and experience on EMS providers' feelings toward pediatric emergencies in a rural state

OBJECTIVE

To determine which factors of training and education influence emergency medical technicians' (EMTs) feelings toward pediatric emergencies in a rural state.

METHODS

A 12-question survey was adapted from a previously studied, nationally administered questionnaire and distributed to all registered EMTs in the state of Maine. Data collected included level of EMT, number of pediatric calls per month, and hours of pediatric continuing education (CE) received. Questions were based upon a 5-point Likert scale and explored level of comfort with various areas of training and education, types of emergencies encountered, and ages of patients.

RESULTS

Eighty-seven percent of all respondents experienced 3 or less (0-3) calls for pediatric emergencies per month, and 73% of all respondents reported receiving 8 or fewer hours of CE in pediatric topics over the previous 2 years. Advanced level of training (EMT-P or EMT-I vs. EMT-B) was associated with increased comfort levels in all areas except Resources (P < 0.05). Additional hours of CE (4+ vs. 0-3) was associated with increased comfort levels in all areas queried (P < 0.05). Increased call volume (4+ vs. 0-3) was associated with increased comfort levels for: children <4 years old, most skills and chief complaints (except Pediatric Assessment by Age, Child Abuse, and Newborn Deliveries), and most aspects of training (except Confidence and Resources) (P < 0.05).

CONCLUSIONS

Level of EMT and hours of CE influence the level of comfort felt by EMTs when confronting a pediatric emergency. Specific CE requirements for topics in pediatric emergency medicine should be considered for all EMTs.

The performance of various rear facing child restraint systems in a frontal crash

Current forward facing (FF) child restraint designs use LATCH and ISOFIX systems to couple the restraint to the vehicle. Rear facing (RF) child restraints, however, have multiple coupling methods that vary by manufacturer and country of origin. Sled tests were performed with the CRABI 12 month dummy in six different RF attachment conditions. The performance of the rear facing child restraints (restraint kinematics, head accelerations, and neck loads) was highly dependent on the coupling method used. The results were also compared to a FF LATCH restraint.

Erectile function after open or endovascular abdominal aortic aneurysm repair

Open abdominal aortic aneurysm repair has been reported to be associated with impairment of sexual function in men, most likely because of autonomic nerve injury and pelvic blood flow changes. Endovascular aneurysm repair does not involve dissection in the area of the iliac bifurcation and therefore may be associated with lower incidence of sexual dysfunction as compared to open repair. We conducted a retrospective study of males after open and endovascular abdominal aortic aneurysm repair to determine if there is a significant difference in the incidence of sexual dysfunction between the two procedures. A modified International Index of Erectile Function Questionnaire was used to access sexual function before and after aneurysm repair. The questionnaire was mailed to all male patients who underwent abdominal aortic aneurysm repair from January 1, 1999 to July 15, 2002. The questionnaire asked patients questions regarding their sexual function before and 3 months after the repair. Questionnaire scores for domains of sexual function (erectile function, orgasmic function, intercourse satisfaction, and overall satisfaction) as well as the total questionnaire score were analyzed. The chi-square and Wilcoxon's signed ranks test were used for statistical comparisons, with p < 0.05 considered significant. Logistic regression was used to examine association. Two hundred ninety-three questionnaires were mailed and 90 were returned completed. There was no difference for the total questionnaire score or the erectile function score before the procedure. Based on the questionnaire score, erectile function worsened after open AAA repair ( p = 0.002). Orgasmic function also deteriorated after open AAA repair ( p = 0.001). Endovascular repair was not accompanied by decreased erectile or orgasmic function ( p = 0.057 and p = 0.068, respectively). Impairment of erectile function was not associated with age, diabetes, or the number of patent hypogastric arteries after aneurysm repair, but there was a significant association between impaired erectile function and open aneurysm repair ( p = 0.036). Endovascular repair of abdominal aortic aneurysms is associated with significantly less impairment of erectile and orgasmic function than that with open repair. Preservation of sexual function after endovascular as compared to open repair should be among the factors considered when weighing treatment options for an abdominal aortic aneurysm in a sexually active male.

Effect of retroviral transduction of canine microvascular endothelial cells on beta(1) integrin subunit expression and cell retention to PTFE grafts

This study evaluated the effect of retroviral transduction on canine microvascular endothelial cell (CMVEC) detachment from fibrin glue coated expanded polytetrafluoroethylene (ePTFE) graft material. CMVEC were isolated from adipose tissue by fluorescent activated cell sorting (FACS). Three treatment groups were evaluated: G-I, transduced CMVEC, selected in antibiotic G418 for 10 days (n=5); G-II, CMVEC selected in G418 and recovered from selection for 4 days (n=5); and G-III, control group of naive CMVEC (n=6). (3)H-thymidine labeled endothelial cells were seeded on fibrin glue coated four-mm diameter PTFE. Grafts were exposed to physiologic shear stresses of 16 dyn/cm(2). Cell detachment was determined by (3)H-thymidine counts in the circuit effluent. beta(1) integrin subunit expression was measured by flow cytometry. After 2 hours of flow exposure, G-I and G-II demonstrated significantly greater cell detachment rates compared with the control seeded grafts. Median peak channel beta(1) integrin subunit value for G-III CMVEC was 2311+/-481.7 vs. 31.5+/-4.51 and 26.3+/-2.0 in the transduced cell groups (p=0.00043). Low beta(1) integrin expression correlated with flow induced high detachment rates of retrovirally-transduced CMVEC.

Infrainguinal arterial reconstructions in patients with aortoiliac occlusive disease: the influence of iliac stenting

OBJECTIVE

Iliac artery angioplasty (IAA) is an effective adjunct when combined with infrainguinal arterial reconstructions (IARs) in appropriate patients with multilevel occlusive disease. However, the effect of iliac artery stenting (IAS) on the outcome of patients undergoing distal bypass procedures is not defined. The purpose of this study was to estimate the influence of previous IAS for iliac occlusive disease on the outcome of IARs, compared with those after IAA alone or aortofemoral bypass grafting procedures (AFBs).

METHODS

During a 5-year period (1995-2000), 105 patients with previous intervention for iliac occlusive disease underwent 120 IARs. The criteria prepared by the Ad Hoc Committee on Reporting Standards (Society for Vascular Surgery/International Society for Cardiovascular Surgery) were followed to define the variables. The TransAtlantic Inter-Society Consensus classification was used to characterize the type of iliac lesions. Univariate (Kaplan-Meier) and multivariate analyses (Cox proportional hazards model) were used to determine the association between preoperative variables and cumulative primary patency.

RESULTS

Forty-five IARs were performed in patients with an earlier IAS repair, 33 in patients with an earlier IAA repair, and 42 in patients with an earlier AFB repair. There were not significant differences between patients in the IAS and IAA groups, except for a more frequent use of polytetrafluoroethylene grafts for IARs in the IAS group (40% vs 15%; chi(2) test, P = .03). The 5-year primary patency rate for IARs was 68% in the IAS group, 46% in the IAA group, and 61% in the AFB group. Univariate analyses revealed that primary patency rates for IARs in patients with previous IAS were significantly higher than those in the IAA group (Kaplan-Meier, log-rank test, P = .02). Previous IAA repair was associated with a two-fold increased risk of IAR graft failure (relative risk, 2.2; 95% CI, 1.1-4.8; P = .04).

CONCLUSIONS

IARs in patients with previous IAS have significantly improved graft patency, compared with those in patients with previous IAA alone. Such graft patency for IAR after IAS is similar to that obtained after AFB repair.

Effect of harvesting and sorting on beta-1 integrin in canine microvascular cells

BACKGROUND

The goal of seeding prosthetic conduits with endothelial cells (ECs) has focused attention on the role of EC adhesion molecules. Cell preparation techniques may affect adhesion molecule expression and graft seeding.

METHODS

Using fluorescent antibody labeling and flow cytometric analysis, this study examined the effectsof monolayer detachment (scraping vs trypsinization), timing of immunolabeling (pre- vs postdetachment), gene transfection (transfected vs nontransfected), and cell selection (antibiotic vs fluorescence sorting) techniques on beta-1 integrin expression in canine microvascular EC (K9MVEC).

RESULTS

Cell scraping resulted in a significantly higher beta-1 integrin mean fluorescence intensity than did cell trypsinization (P < 0.05). No difference was observed with immunolabeling prior to versus following monolayer harvesting. Gene transfection had no significant effect on beta-1 integrin expression. No advantage was observed between cell selection methods (P > 0.05).

CONCLUSION

This study suggests that the monolayer harvesting technique employed has a significant impact on beta-1 integrin quantification by flow cytometric analysis. Furthermore, microvascular EC expression of beta-1 integrin was not adversely affected by gene transfection.

External iliac and common iliac artery angioplasty and stenting in men and women

OBJECTIVE

The effect of anatomic location of stent placement on the outcome of iliac artery angioplasty and stenting is not defined. Analyses of patency rates of external iliac artery (EIA) and common iliac artery (CIA) stents have provided conflicting results and have not considered men and women independently. The purpose of this study was to estimate the influence of the anatomic location of stenting on the outcome of iliac angioplasty and stent placement in both men and women.

METHODS

From 1995 to 1999, 247 iliac angioplasty and stent placement procedures (303 stents) were performed in 67 women and 122 men, and all were included in a retrospective cohort study. The criteria prepared by the Ad Hoc Committee on Reporting Standards (Society for Vascular Surgery/International Society for Cardiovascular Surgery) were followed. The TransAtlantic Inter-Society Consensus classification was used to characterize the type of iliac lesions. Both univariate (Kaplan-Meier [KM]) and multivariate analyses (Cox proportional hazards model) were used to determine the association among the variables, cumulative patency, limb salvage, and survival.

RESULTS

Indications for iliac angioplasty with stenting were disabling claudication (65%), limb salvage (33%), and blue toe syndrome (2%). Primary stenting was performed in 103 procedures (42%). Stents were placed selectively after iliac angioplasty mainly for residual stenosis or pressure gradient (43%). Patients with EIA stents, as compared with those who had CIA stents, had more extensive lesions (TransAtlantic Inter-Society Consensus type C lesions), poorer runoff, smaller vessel size, and less frequency of hyperlipidemia (P <.05). Primary patency rates at 1, 3, and 5 years were 76%, 56%, and 56%, respectively, for patients with EIA stents and 92%, 85%, and 76%, respectively, for those with CIA stents. Although overall primary patency rates were significantly decreased in patients with EIA lesions (KM, log-rank test, P =.001), stratified analyses revealed that women with EIA stents had the poorest outcome, with 61%, 47%, and 23% primary patency rates at 1, 3, and 5 years, respectively, (KM, log-rank test, P <.001). Cox regression analysis identified EIA stenting (relative risk, 4.3; 95% CI, 2.3-7.9; P <.001) as an independent predictor of decreased primary patency in women but not in men.

CONCLUSIONS

Women undergoing EIA angioplasty with stent placement have significantly reduced primary patency rates. Despite initial technical success, these patients are at increased risk of long-term failure and might require subsequent procedures to obtain clinical success. Conversely, men undergoing EIA stenting have a more favorable outcome than women.

IL-1alpha and TNFalpha down-regulate CRH receptor-2 mRNA expression in the mouse heart

Two receptors (CRH receptor type 1 and CRH receptor type 2) have been identified for the stress-induced neuropeptide, CRH and related peptides, urocortin, and urocortin II. We previously found marked down-regulation of cardiac CRH receptor type 2 expression following administration of bacterial endotoxin, lipopolysaccharide, a model of systemic immune activation, and inflammation. We postulated that inflammatory cytokines may regulate CRH receptor type 2. We show that systemic IL-1alpha administration significantly down-regulates CRH receptor type 2 mRNA in mouse heart. In addition, TNFalpha treatment also reduces CRH receptor type 2 mRNA expression, although the effect was not as marked as with IL-1alpha. However, CRH receptor type 2 mRNA expression is not altered in adult mouse ventricular cardiomyocytes stimulated in vitro with TNFalpha or IL-1alpha. Thus, cytokine regulation may be indirect. Exogenous administration of corticosterone in vivo or acute restraint stress also reduces cardiac CRH receptor type 2 mRNA expression, but like cytokines, in vitro corticosterone treatment does not modulate expression in cardiomyocytes. Interestingly, treatment with urocortin significantly decreases CRH receptor type 2 mRNA in cultured cardiomyocytes. We speculate that in vivo, inflammatory mediators such as lipopolysaccharide and/or cytokines may increase urocortin, which in turn down-regulates CRH receptor type 2 expression in the heart. Because CRH and urocortin increase cardiac contractility and coronary blood flow, impaired CRH receptor type 2 function during systemic inflammation may ultimately diminish the adaptive cardiac response to adverse conditions.

Influence of hormone replacement therapy on the outcome of iliac angioplasty and stenting

OBJECTIVE

Thromboembolic events are more frequent in women with established cardiovascular disease taking hormone replacement therapy (HRT). The effect of HRT on the outcome of women with aortoiliac occlusive disease is unknown. The purpose of this study was to estimate the influence of risk factors, including HRT, on the outcome of women undergoing iliac artery angioplasty and stent placement.

METHODS

During a 5-year period (between 1994 and 1999), 126 iliac angioplasties with stent placement (144 stents) were performed in 88 women. The criteria prepared by the Ad Hoc Committee on Reporting Standards (Society for Vascular Surgery/International Society for Cardiovascular Surgery) were followed to define the variables. Both univariate (Kaplan-Meier) and multivariate analyses (Cox proportional hazards model) were used to determine the association among preoperative variables, cumulative patency, limb salvage, and survival.

RESULTS

The patients' average age was 63.2 years with 43% of the patients taking HRT. Indications for iliac angioplasty with stenting were disabling claudication (65%), limb salvage (32%), and blue toe syndrome (3%). The technical success rate was 95% (120 of 126 procedures). Primary stenting was performed in 28 patients (22%). Stents were placed selectively after iliac angioplasty for residual stenosis or pressure gradient (57%), iliac dissection (8%), long-segment occlusions (8%), or eccentric lesions (5%). There were no significant differences between HRT users and nonusers with regard to risk factors, except there was a higher frequency of diabetes in women taking HRT. Overall, the primary patency rate was 76% at 1 year, 67% at 3 years, and 62% at 5 years. Primary patency rates at 1, 3, and 5 years were 75%, 57%, and 49% for users of HRT and 77%, 74%, and 74%, respectively, for nonusers. Limb salvage rates were not statistically different between users and nonusers of HRT at 5 years (95% vs 96%). Univariate and Cox regression analyses identified HRT use (Kaplan-Meier, log-rank test, P = .02; relative risk, 2.4; 95% CI, 1.3-4.5; P = .006) and stent placement in the external iliac artery (relative risk, 4.3; 95% CI, 2.3-7.9; P < .001) as independent predictors of decreased primary patency.

CONCLUSIONS

Women undergoing iliac angioplasty with stent placement who are taking HRT have significantly reduced primary patency rates. Despite initial technical success, HRT users are at increased risk of long-term failure and might require subsequent procedures to obtain clinical success. External iliac angioplasty and stenting are also associated with decreased primary stent patency in women.

Influence of hormone replacement therapy on graft patency after femoropopliteal bypass grafting

OBJECTIVE

Thromboembolic events are more frequent in women with established cardiovascular disease who are receiving hormone replacement therapy (HRT). The effect of HRT on the outcome of women undergoing infrainguinal bypass grafting is unknown. The purpose of this study was to estimate the influence of risk factors, in particular HRT, on the outcome of women undergoing femoropopliteal bypass grafting.

METHODS

During a 5-year period (between 1993 and 1998), 131 femoropopliteal bypass graft procedures were performed in 106 women. The criteria prepared by the Ad Hoc Committee on Reporting Standards (Society for Vascular Surgery/North American Chapter of the International Society for Cardiovascular Surgery) were followed. Both univariate (Kaplan-Meier method) and multivariate analyses (Cox proportional hazards model) were used to determine the association among preoperative variables, graft patency, limb salvage, and survival.

RESULTS

The average age of the patients was 66.4 years; 26% of the patients were receiving HRT. Indications for femoropopliteal bypass grafting were limb salvage (80%) and disabling claudication (20%). Autogenous vein was used in 48% of procedures, polytetrafluoroethylene (PTFE) in 49%, and PTFE-vein composite grafts in 3%. Distal popliteal anastomosis was above the knee in 52% and below the knee in 48%. Overall primary patency rate was 81% at 1 year, 65% at 3 years, and 56% at 5 years. Primary patency rates at 1, 3, and 5 years were 75%, 45%, and 23%, respectively, for HRT users and 84%, 72%, and 65%, respectively, for nonusers of HRT. Overall, cumulative 1- and 5-year limb salvage results were 96% and 92%, respectively, and long-term survival at 1, 3, and 5 years was 96%, 86% and 74%, respectively. With univariate and Cox regression analyses, HRT was identified as the only independent predictor of reduced primary graft patency (Kaplan-Meier method, log-rank test, P =.004; relative risk, 2.5; 95% CI, 1.3-4.8). Women receiving HRT who underwent a procedure with PTFE had the lowest primary graft patency rates (relative risk, 3.4; 95% CI, 1. 5-7.8; P =.006).

CONCLUSIONS

Women undergoing femoropopliteal bypass graft procedures who are receiving HRT have significantly reduced primary graft patency rates. The risk of graft failure increases when prosthetic materials are used.

Heparin-induced thrombocytopenia

Heparin-induced thrombocytopenia is a rare but complex adverse drug reaction that can produce devastating results. Treatment and clinical management of the patient requires close observation and education of the pathophysiology occurring at the cellular level. Documented cases of heparin-induced thrombocytopenia have been reported in the literature for years. This case presentation details a multiple trauma patient in whom heparin-induced thrombocytopenia developed and the effect this syndrome had on her treatment and eventual recovery.

Abnormal adaptations to stress and impaired cardiovascular function in mice lacking corticotropin-releasing hormone receptor-2

The actions of corticotropin-releasing hormone (Crh), a mediator of endocrine and behavioural responses to stress, and the related hormone urocortin (Ucn) are coordinated by two receptors, Crhr1 (encoded by Crhr) and Crhr2. These receptors may exhibit distinct functions due to unique tissue distribution and pharmacology. Crhr-null mice have defined central functions for Crhr1 in anxiety and neuroendocrine stress responses. Here we generate Crhr2-/- mice and show that Crhr2 supplies regulatory features to the hypothalamic-pituitary-adrenal axis (HPA) stress response. Although initiation of the stress response appears to be normal, Crhr2-/- mice show early termination of adrenocorticotropic hormone (Acth) release, suggesting that Crhr2 is involved in maintaining HPA drive. Crhr2 also appears to modify the recovery phase of the HPA response, as corticosterone levels remain elevated 90 minutes after stress in Crhr2-/- mice. In addition, stress-coping behaviours associated with dearousal are reduced in Crhr2-/- mice. We also demonstrate that Crhr2 is essential for sustained feeding suppression (hypophagia) induced by Ucn. Feeding is initially suppressed in Crhr2-/- mice following Ucn, but Crhr2-/- mice recover more rapidly and completely than do wild-type mice. In addition to central nervous system effects, we found that, in contrast to wild-type mice, Crhr2-/- mice fail to show the enhanced cardiac performance or reduced blood pressure associated with systemic Ucn, suggesting that Crhr2 mediates these peripheral haemodynamic effects. Moreover, Crhr2-/- mice have elevated basal blood pressure, demonstrating that Crhr2 participates in cardiovascular homeostasis. Our results identify specific responses in the brain and periphery that involve Crhr2.

Vascular smooth muscle cell apoptosis in aneurysmal, occlusive, and normal human aortas

PURPOSE

Apoptosis is a physiologic mechanism of cell death that regulates mass and architecture in many tissues. Apoptosis has been described as a feature in human vascular atherosclerosis and large vessel structural integrity. We examined the extent of vascular smooth muscle cell (VSMC) apoptosis in aneurysmal, occlusive, and normal human aortic tissue.

METHODS

Tissue samples of aneurysmal, occlusive, and normal human infrarenal aorta were evaluated. DNA fragmentation detection methods, immunohistochemistry, and DNA electrophoresis determined VSMC density, VSMC apoptosis, and apoptosis markers. Apoptotic cells and VSMC nuclei were counted with the use of computer-generated image analysis. Aortic subtypes were compared statistically by analysis of variance.

RESULTS

Seventeen aneurysmal, ten occlusive, and five normal human aortas were evaluated. By alpha(1)-actin immunostaining, VSMC density was least in aneurysmal aortas (271.8 +/- 13.5 cells/high-power field [HPF]) compared with occlusive aorta (278.2 +/- 39.4 cells/HPF) and normal aortas (291.0 +/- 25.4 cells/HPF; P = not significant). Presence of apoptotic VSMCs was demonstrated by terminal deoxynucleotidyl transferase fragment end labeling and propidium iodide nuclear staining. VSMC apoptosis was greatest within aneurysmal aortas with 11.7 +/- 1.5 cells/HPF compared with occlusive aortas with 3.3 +/- 0. 8 cells/HPF (P <.05) and normal aortas with 3.75 +/- 4.6 cells/HPF (P <.05). Significant differences in apoptosis markers, p53 or bcl-2, could not be demonstrated by immunohistochemistry or DNA electrophoresis in aortic subtypes.

CONCLUSION

Apoptosis of VSMCs is increased and VSMC density is decreased within the medial layer of aneurysmal aortic tissue. Structural degeneration of aortic tissue at the cellular level contributes to aneurysmal formation.

Developmental expression of alloantigen systems in the chicken

The different allelic forms of nine non-Mhc alloantigen systems of the chicken were examined for developmental expression on erythrocytes isolated from embryos and young chicks. Polyclonal alloantisera raised against the different antigens were used to detect these antigens on the cell surface by hemagglutination as well as by indirect immunofluorescence. The developmental stage of initial expression on erythrocytes for each of the genetic systems investigated (i.e., A, E, C, D, H, I, K, L and P) varied from day 4 to day 14 of incubation. The different antigens of each system appeared simultaneously at a particular stage of development except for those of the I system, where the I8 allelic form appeared earlier than I2.

Factors affecting the surgical management of infective endocarditis

Congestive heart failure and septic embolism complicate the clinical course of patients with infective endocarditis (IE). This study reviews the clinical records of patients with systemic disease secondary to IE and stratifies their disease severity according to individual risk factors and medical, and surgical interventions. The hospital records of all patients presenting to our institution from 1992 through 1997 with heart valve destruction secondary to IE were reviewed. Ten patients with hemodynamically significant valve lesions were included in this study: seven with aortic valve disease and two with mitral valve disease, and one with combined aortic and mitral valve lesions. All were diagnosed by echocardiogram. All ten patients experienced systemic septic arterial emboli: four intracranial lesions, four visceral lesions, and three extremity arterial occlusive events. Two patients required peripheral arterial repair. Cultures revealed infection secondary to Staphylococcus aureus in five, Streptococcus species in three, Coxiella species in one, and an unidentified organism in one patient. Seven patients underwent valve replacement. Three patients died from their disease processes. Statistical significance was established by Wilcoxon rank analysis with a two-tailed P < 0.05. Patients with IE secondary to staphylococcal infections suffered a more acute and virulent disease process (P = 0.04), with a 40 per cent mortality rate in the first 48 hours. There was no increased incidence of embolization associated with longer duration of symptoms (P = 0.32). Surgical repair conferred improved clinical outcome as compared with no surgical intervention (P = 0.03). Improved patient outcome was associated with nonstaphylococcal infection (P = 0.02), and a successful initial antibiotic regimen (P = 0.03). Peripheral arterial repair was successful in both cases.

Mesenteric pseudoaneurysm resulting from septic embolism

Symptomatic peripheral septic embolism is a rare systemic complication of infective endocarditis. This case report describes abdominal pain secondary to a septic pseudoaneurysm in the distal superior mesenteric artery. Presentation, imaging, surgical intervention, and histologic evaluation are described, and a review of recent literature relating to this phenomenon is outlined.

Mechanical characteristics of lyophilized human saphenous vein valves

PURPOSE

We investigated the mechanical characteristics of lyophilized human saphenous vein valves to determine their suitability for use as allogeneic transplants to treat chronic venous insufficiency.

METHODS

Fresh cadaveric veins were lyophilized in vacuum bottles within 24 hours of harvest and were stored at room temperature. The veins were reconstituted in saline solution and then were placed in an in vitro flow circuit for evaluation. At varied flow rates, pressures proximal and distal to valves during prograde and retrograde flow were measured. Valve closure times were determined with Doppler examination and spectral analysis. The valves were also stressed to 350 mm Hg on a separate apparatus.

RESULTS

All pressures proximal and distal to the valves remained less than 10 mm Hg during prograde flow. A pressure gradient developed immediately on the reversal of flow. Pressure as high as 200 mm Hg applied against the closed valves was not transmitted beyond the valve. Valve closure times had a mean of 0.31 +/- 0.03 seconds and 0.21 +/- 0.01 seconds for the Doppler examination and spectral analysis, respectively. All valves withstood stress pressures to 350 mm Hg.

CONCLUSIONS

The in vitro mechanical characteristics of the valves of lyophilized veins are similar to known values for normal in vivo valves.

Surgical management of flash pulmonary edema secondary to renovascular hypertension

BACKGROUND

Flask pulmonary edema (FPE) may be a manifestation of renovascular hypertension (RVHTN) and unresponsive to antihypertensive therapy.

METHODS

Response to antihypertensive therapy and perioperative outcomes were determined in 5 consecutive patients with FPE.

RESULTS

A mean of 2.3 admissions for the treatment of FPE were observed despite a mean cardiac ejection fraction of 60%. Preoperative treatment was attempted for 12 days and included ventilatory support (n = 3) and hemodialysis (n = 2). Total decreased renal perfusion was demonstrated by arteriography and radionuclide scans, no patient having a functional, contralateral kidney. Renal revascularizations were not associated with mortalities; 1 patient experienced atalectasis requiring bronchoscopy. All patients were extubated within 48 hours of surgery. A significant reduction in blood pressure (BP, 46%) and serum creatinine (Cr, 53%, P < or = 0.05) was observed. A mean of 1 antihypertensive medication was required at discharge compared with 3.4 on admission. At follow-up (mean 57 months) all patients remain cured of FPE.

CONCLUSIONS

Medical management was unsuccessful in the treatment of FPE. Renal revascularization was associated with low morbidity and mortality, control of BP, restoration of renal function, and cure of FPE. These data suggest surgical intervention is the optimal mode of treatment of RVHTN associated with FPE.

Biopsy specimen findings in patients with previous lower extremity cellulitis after saphenous venectomy for coronary artery bypass graft surgery

BACKGROUND

No previous study has examined the immune and inflammatory mechanisms involved in the pathogenesis of lower extremity cellulitis after saphenous venectomy for coronary artery bypass graft surgery.

OBJECTIVE

Our purpose was to determine the histopathologic, immunologic, and inflammatory findings in skin biopsy specimens from saphenous venectomy limbs of patients with previous bouts of cellulitis.

METHODS

Biopsy specimens were obtained from five patients with previous episodes of cellulitis. Specimens of the contralateral lower extremity of each patient were obtained for controlled comparisons.

RESULTS

Histopathologic findings did not provide evidence that could account for the tendency for cellulitis to develop. Moreover, the distribution of CD1a, HLA-DR, intercellular adhesion molecule-1, and lymphocyte function-associated antigen type 1 were similar in specimens from the postvenectomy and contralateral legs. No tumor necrosis factor-alpha expression was found in specimens from the lower extremities.

CONCLUSION

The mechanisms responsible for the production of this disorder do not involve the mediators studied.

Effect of intra-arterial environment on endothelialization and basement membrane organization in polytetrafluoroethylene grafts

PURPOSE

To determine if a complete intra-arterial environment affects endothelialization rate and basement membrane organization in polytetrafluoroethylene (PTFE) grafts.

METHOD

Thirty dogs underwent either infrarenal abdominal aorta PTFE interposition (12) or intraluminal stented (18) grafting. Grafts were explanted at 4 and 8 weeks and rate of endothelial ingrowth calculated. Endothelial cells were identified and basement membrane organization assessed using antibodies against endothelial cell-specific surface antigen CD31, type IV collagen, and laminin.

RESULTS

Endothelialization rates, expressed as percent graft surface area coverage per week, were 3.7% +/- 0.62% (4-week control), 12.9% +/- 0.58% (4-week stented), 4.2% +/- 0.62% (8-week control), and 10.0% +/- 0.54% per week (8-week stented grafts). Endothelial repaving rates were constant for control and increased in all stented grafts (P <0.01). At 4 weeks, laminin was identified in all control (6 of 6) and no stented grafts. Staining was confined to the 20% of the hyperplastic intimal area immediately below the endothelium. At 4 weeks, type IV collagen was present throughout the entire hyperplastic intima in control specimens but was confined to a discrete subendothelial zone in stented grafts. By 8 weeks, type IV collagen became concentrated in the luminal one third of the intima in control grafts.

CONCLUSION

Intra-arterial graft location is associated with early formation of an organized basement membrane and accelerated endothelialization in PTFE grafts.

Effect of balloon-expandable and self-expanding stent fixation on endoluminal polytetrafluoroethylene graft healing

PURPOSE

To investigate the effect of stent design and deployment mechanism on endoluminal graft healing.

METHOD

Twenty dogs underwent infrarenal abdominal aorta polytetrafluoroethylene (PTFE) interposition (6) or intraluminal stented grafting using either a balloon expandable (BE, n = 8) or self-expanding (SE, n = 6) stent design. Grafts were removed at 8 weeks. Length of endothelial ingrowth and intima to media height ratios (IMHR) were calculated. Perianastomotic smooth muscle (Actin+), macrophage (CD44+), proliferating (PCNA+), and platelet-derived growth factor (PDGF+) cell content were determined.

RESULTS

Mean endothelial ingrowth was 1.10 +/- 0.15 cm (control), 1.88 +/- 0.13 cm (BESG), and 2.16 +/- 0.18 cm (SESG) proximally; and 0.94 +/- 0.12, 2.11 +/- 0.11 cm, and 2.16 +/- 0.15 cm, respectively, at the distal anastomosis. Endothelial ingrowth was greater in all stented grafts (P <0.001). Mean IMHRs were 1.42 +/- 0.16 (control), 0.50 +/- 0.14 (BESG), and 0.77 +/- 0.2 (SESG) proximally; and 0.84 +/- 0.1, 0.42 +/- 0.09, and 0.77 +/- 0.12 (SESG) distally. Lower IMHRs were observed in all stented graft regions (P <0.05) except the distal anastomosis of SESG. The PDGF+ and PCNA+ cell content was decreased, and Actin+ cell content was increased in all stented grafts (P <0.05).

CONCLUSION

Intraluminal location enhances endothelialization and attenuates intimal thickening in PTFE grafts. The enhanced healing of intraluminal stented grafts is irrespective of the type of stent or deployment mechanism used.

Retroviral mediated gene transduction alters integrin expression on vascular endothelial cells

Genetically recombinant endothelial cells (rEC) may improve the patency of small diameter vascular grafts by preventing thrombosis or limiting neointimal hyperplasia. Previous work has shown that rEC have reduced adhesion to vascular bypass grafts in vivo. Poor adhesion may be due to altered adhesion (integrin) receptors. This study evaluated the expression of the alpha 5 beta 1 (fibronectin), alpha 2 beta 1 (collagen IV), and alpha v beta 3 (vitronectin) integrin subunits on rEC. Human umbilical vein EC or canine jugular vein EC were transduced with neoR, neoR and human tPA or hygromycin resistance genes using retroviral vectors. Naive EC and EC exposed to empty viral particles (mEC) were controls. Naive EC, mEC, and all rEC's were evaluated for alpha and beta subunits for each integrin receptor studied using immunoblotting. Blotting for alpha 2, alpha 5, and alpha v exhibited expression of the alpha integrin subunits in all cells. The beta 1 and beta 3 subunits were present in mEC and nEC but were absent or truncated in all rEC. The decreased adhesion of rEC's to synthetic vascular grafts may be accounted for by their altered beta 1 and beta 3 integrin subunit expression. The beta subunit is critical for organization of the cytoskeleton and cellular signal transduction. Diminished beta subunit expression in rEC is neither vector specific nor related to retroviral exposure alone. Alteration of beta integrin expression may be to associated with the over-expression of phosphotransferase genes such as neoR or hygromycin B used as selectable markers in gene transfer protocols.

Predictors of survival after inferior vena cava injuries

In patients with inferior vena cava (IVC) injuries, predictors of survival are investigated. From 1987 to 1995, 27 IVC injuries were identified among 514 patients with vascular trauma. The ability of clinical determinants to predict survival were retrospectively assessed. IVC injuries occurred in 7 females and 20 males (mean age, 27.7 +/- 2.5 years) from both blunt (n = 14) and penetrating (n = 13) trauma. The mean revised trauma score was 10.2 +/- 0.6. Injuries were treated by primary repair (n = 22), ligation (n = 4), or prosthetic grafting (n = 1). Thirteen patients died (48%), 10 within 12 hours of admission. Suprahepatic (n = 2), retrohepatic (n = 12), suprarenal (n = 1), and infrarenal (n = 12) injuries were associated with 100, 67, 100, and 20 per cent mortality, respectively. Blood transfusions (16 +/- 4 vs 23 +/- 4 units), coagulation factor replacement (7 +/- 2 vs 7 +/- 2 units), and electrolyte solution use (8.6 +/- 1.4 vs 9.6 +/- 1.4 L) were similar among survivors and nonsurvivors. Four complications [venous hypertension (n = 2), IVC thrombosis (n = 1), and pulmonary embolus (n = 1)] occurred in the 14 survivors (28.6%). Blunt injury, revised trauma score, free perforation, injury location, intraoperative hypotension, and blood loss were predictive of mortality. IVC injuries remain extremely lethal, and improved survival is associated with infrarenal penetrating injuries and a contained hematoma.

Concomitant orthopedic and vascular injuries as predictors for limb loss in blunt lower extremity trauma

Lower extremity trauma with concomitant orthopedic and vascular injury is associated with a high degree of limb loss. Despite successful arterial repair, many patients will ultimately require amputations. The effect of associated orthopedic injuries on limb loss in patients with lower extremity arterial injuries is investigated. From 1989 to 1994, 52 infrainguinal arterial injuries were identified among 365 vascular trauma patients. Clinical determinants were retrospectively assessed for the ability to predict postoperative amputations. Femoral artery injuries were present in 23 patients, with 53 per cent the result of blunt trauma. The incidence of lower extremity fractures was 53 per cent (60% open). Seventy-nine per cent of femoral artery injuries were repaired with saphenous vein grafts. Popliteal artery injuries were present in 13 patients, with 77 per cent the result of blunt trauma. The incidence of lower extremity fractures and posterior knee dislocations was 85 per cent (73% open) and 38 per cent, respectively. Ninety-two per cent of injuries were repaired with saphenous vein grafts. Tibial artery injuries were present in 16 patients, with 44 per cent the result of blunt trauma. The incidence of lower extremity fractures was 81 per cent (46% open). Twenty-five per cent of tibial artery injuries were treated with arterial repair, and 31 per cent with arterial ligation. Fourteen above-knee (AKA) and two below-knee amputations were performed. Amputation rates were 26.1 per cent (three AKAs) for femoral, 53.8 per cent (seven AKAs) for popliteal, and 38 per cent (four AKAs, two below-knee amputations) for tibial artery injuries. At the popliteal and femoral locations, greater than two long-bone fractures was predictive of amputation. For tibial arteries, one-vessel (n = 10), two-vessel (n = 3), and three-vessel (n = 3) injuries were associated with 20, 33, and 100 per cent amputations rates, respectively. Blunt injury, pulseless extremity, need for arterial repair (rather than ligation or no therapy), increasing number of injured tibial vessels, and multiple long-bone fractures were predictors of amputation (P < 0.05). Distal vascular injuries combined with complex orthopedic fractures are more likely to result in limb loss. Two or more long-bone fractures is predictive of amputation at all three locations.

Healing characteristics of intraarterial stent grafts in an injured artery model

Previous investigations reveal in the absence of endothelial cell (EC) injury, intraarterial polytetrafluoroethylene (PTFE) stent graft (SG) exhibit greater EC repaving than PTFE interposition grafts (CG). The investigation evaluated EC repaving of SG compared to CG after balloon injury. Twenty adult dogs underwent SG (n = 10) or CG (n = 10) placement in the infrarenal aorta after balloon injury with harvest at 1 and 6 weeks. Endothelial repaving, intima-to-media height ratios (IMHR), and inflammatory stains were performed. Endothelial repaving was greater in 6-week SG compared to CG (51% +/- 5.0 versus 10% +/- 5.0, p < or = 0.05). IMHR was less in 6-week SG compared to CG at the proximal (1.22 +/- 0.16 versus 1.82 +/- 0.16, p < or = 0.05) and distal anastomosis (0.81 +/- 0.25 versus 1.33 +/- 0.25, p < or = 0.05). Smooth muscle cell (SMC) alpha-actin was greater in 1-week SG compared to CG at the distal anastomosis (121.5 +/- 7.2 versus 94.0 +/- 7.2, p < or = 0.05). Proliferating cell nuclear antigen (PCNA) was less in 6-week SG compared to CG at the proximal (5.6 +/- 1.4 versus 9.4 +/- 1.1, p < or = 0.05) and distal anastomosis (3.8 +/- 0.6 versus 11.2 +/- 1.1, p < or = 0.05). Macrophage CD-44 was less in 6-week SG compared to CG at the proximal (10.4 +/- 1.6 versus 32.6 +/- 3.6, p < or = 0.05) and distal anastomosis (8.6 +/- 0.9 versus 35.6 +/- 3.6, p < or = 0.05). Intraarterial SG placed after balloon injury exhibited significantly greater endothelialization and less intimal hyperplasia when compared to CG.

The role of platelet-derived growth factor in intraluminal stented graft healing

BACKGROUND

Intraluminally placed polytetrafluoroethylene grafts are associated with enhanced graft endothelialization and diminished intimal hyperplasia when compared with interposition grafts. This study determined the role of platelet-derived growth factor in intraluminal graft healing.

STUDY DESIGN

Thirty dogs underwent infrarenal abdominal aorta polytetrafluoroethylene interposition (control, n = 15) or intraluminal stented (n = 15) grafting. Grafts were explanted at 1, 3, and 6 weeks. The percent of graft area endothelialization and intima to media height ratios were calculated. By using protein electrophoresis and the Western blot technique, platelet-derived growth factor, identified by immunolabeling with anti-platelet-derived growth factor antibody, was isolated from proximal, mid-, and distal graft regions and was quantified using densitometry.

RESULTS

Graft area endothelialization was 0 +/- 3.3 percent, 2.3 +/- 3.3 percent, and 19.0 +/- 3.3 percent for 1-, 3-, and 6-week controls; and 4.7 +/- 3.7 percent, 30.5 +/- 3.3 percent, and 86.8 +/- 3.3 percent for 1-, 3-, and 6-week stented grafts. Endothelialization was greater in stented grafts at 3 and 6 weeks (p < .01). Proximal anastomosis intima to media height ratios were 1.61 +/- 0.15, 1.54 +/- 0.14, and 1.48 +/- 0.15 for 1-, 3-, and 6-week control grafts, and 0.42 +/- 0.18, 0.41 +/- 0.15, and 0.47 +/- 0.14 for 1-, 3-, and 6-week stented grafts. Similar intima to media height ratio values were present at the distal anastomosis. Lower intima to media height ratios were observed in all stented grafts (p < .01). The platelet-derived growth factor content at 1-, 3-, and 6-weeks was lower in all stented grafts when compared with controls. The content of platelet-derived growth factor was greatest in 3-week controls, with a significant difference noted in the mid-graft region (p < .05). The content of platelet-derived growth factor remained stable in all stented graft regions over 6 weeks. An inverse correlation between stented graft platelet-derived growth factor content and endothelialization (r = -0.43) and a positive correlation with proximal anastomotic intimal hyperplasia (r = 0.73) were identified.

CONCLUSIONS

Lower platelet-derived growth factor content is associated with decreased intimal hyperplasia and improved healing in intra-arterial polytetrafluoroethylene grafts.

Effects of azathioprine withdrawal in kidney recipients with stable function two years after transplant

To assess the effects of azathioprine withdrawal, renal recipients with grafts > 2 yr function (103 study patients) were tapered off azathioprine over a 1-yr period and compared to 69 patients 2 yr after transplant who were not tapered (controls). Of the 103 study patients, 16 (15%) were living-donor transplants and 87 were cadaveric. Of the 69 control patients, 9 (13%) were living related transplants and 60 were cadaveric. The mean HLA match for those tapered was 3.3 Ag and 3.1 Ag for those remaining on azathioprine. Two study patients restarted azathioprine on their own. Age, sex, and cause of renal failure in both groups was similar. Of the 101 study patients remaining, 9 (8.8%) returned to dialysis due to biopsy proven chronic rejection. There were no acute rejection episodes. Six of the 69 control patients (8.7%) also returned to dialysis for the same reason. Of the 92 patients who have completed the taper, 85 have been off azathioprine for six or more months. There was not a significant difference between the mean 12- and 24-month creatinine levels of the study patients (1.6 mg%, 1.7 mg%) and those of the controls (1.5 mg%, 1.8 mg%). The mean 12- and 24-month hematocritis of patients tapered (41.3%, 40.8%) were comparable with patients not tapered (42.3%, 42.8%). Of interest, the mean hematocritis of both study and control patients rose from 28.9% and 33.5%, respectively, to 41.3% and 42.3% 1 yr following entry into the study. The mean 12- and 24-month white blood counts of those tapered (8.9, 8.7) did not differ significantly from those continued on azathioprine (8.8, 8.8). In stable renal transplant patients on triple drug immunosuppression for at least 2 yr, azathioprine can be discontinued, in a tapered protocol, without an increased risk of graft loss or compromise of renal function.

Vascular endothelial growth factor and heparin in a biologic glue promotes human aortic endothelial cell proliferation with aortic smooth muscle cell inhibition

BACKGROUND

Incomplete luminal endothelialization may contribute to small diameter vascular graft failure. Vascular endothelial growth factor (VEGF) can be used to stimulate endothelialization without provoking smooth muscle cell (SMC) proliferation. Heparin and VEGF in a fibrin glue (FG) were investigated for their ability to promote selective human aortic endothelial cell (HAEC) proliferation and human aortic smooth muscle cell (HASMC) inhibition.

METHODS

HAECs and HASMCs were seeded on FG containing VEGF (2.5, 10, 30, 100 ng/ml) or VEGF and heparin (5, 50, 500 units/ml). Proliferation assays were performed with tritiated thymidine on days 1 and 3. Results were analyzed by ANOVA, with p < or = 0.05 significant.

RESULTS

HAEC proliferation on FG with 10, 30, and 100 ng/ml VEGF was significantly greater than FG alone at days 1 and 3. The addition of 50 units/ml heparin to VEGF significantly increased HAEC proliferation to greater than FG with VEGF alone at day 1. Human aortic SMC proliferation was not stimulated by the addition of VEGF. The addition of 5, 50, and 500 units/ml heparin significantly inhibited HASMC proliferation regardless of VEGF concentration.

DISCUSSION

VEGF at 10 ng/ml combined with heparin at 50 units/ml exhibited maximal stimulation of HAECs with inhibition of HASMCs. VEGF and heparin in a biologic glue may improve patency by selectively promoting HAEC proliferation without HASMC growth on synthetic vascular bypass grafts.

Healing characteristics of intraarterial stented grafts: effect of intraluminal position on prosthetic graft healing

BACKGROUND

The purpose of this study was to investigate the effect of complete intraluminal placement on prosthetic graft healing.

METHODS

Thirty dogs underwent infrarenal abdominal aorta polytetrafluoroethylene interposition (12) or intraluminal stented (18) grafting. Grafts were removed at 4 and 8 weeks. Length of endothelial ingrowth and intima to media height ratios (IMHRs) were calculated. Perianastomotic endothelial (CD31+, factor VIII [FVIII+]), smooth muscle (actin+), macrophage (CD44+), and proliferating (PCNA+) cell content was determined.

RESULTS

In control grafts mean proximal and distal anastomotic endothelial cell ingrowth was 0.42 +/- 0.06 and 0.47 +/- 0.08 cm at 4 weeks and 1.10 +/- 0.24 and 0.94 +/- 0.17 cm at 8 weeks. In intraluminal grafts mean proximal and distal anastomotic endothelial cell ingrowth was 1.57 +/- 0.09 and 1.54 +/- 0.12 cm at 4 weeks and 1.88 +/- 0.06 and 2.11 +/- 0.25 cm at 8 weeks. Endothelial ingrowth was greater in all stented grafts (p < 0.001). Mean proximal anastomosis IMHRs were 1.01 +/- 0.16 for 4-week and 1.42 +/- 0.16 for 8-week control grafts and 0.59 +/- 0.18 for 4-week and 0.50 +/- 0.14 for 8-week stented grafts. Similar IMHR values were present at the distal anastomosis. Lower IMHRs were observed in stented grafts (p < 0.05). Content of CD44+, PCNA+, and FVIII+ cells were reduced both proximally and distally in 4-week stented grafts (p < 0.05). Distal content of CD31+ and actin+ cells was greater in 4-week stented grafts (p < 0.05). At 8 weeks CD44+ cell content decreased in controls (p < 0.05).

CONCLUSIONS

Intraluminal location enhances prosthetic graft reendothelialization and attenuates intimal thickening.

Effect of endoluminal PTFE graft placement on cell proliferation, PDGF secretion, and intimal hyperplasia

To determine the effects of intraluminal placement on peri-anastomotic intimal hyperplasia and platelet derived growth factor (PDGF) secretion in polytetrafluoroethylene (PTFE) grafts. Infrarenal aortic PTFE grafts were placed in 30 dogs as either interposition (n = 12) or intraluminal stented (n = 18) grafts. Grafts were explanted at 4 and 8 weeks. At each anastomosis, intima to media height ratios (IMHR) were calculated, and smooth muscle (Actin), proliferating (PCNA), and PDGF secreting cell content determined using cell-specific immunohistochemical stains. At the proximal anastomosis, control and stented graft IMHRs were 1.01 +/- 0.16 vs 0.59 +/- 0.18 in 4-week and 1.42 +/- 0.16 vs 0.50 +/- 0.14 in 8-week specimens. Similar IMHR values were present for the distal anastomosis. Peri-anastomotic PCNA cell counts were greater in control grafts at both 4 and 8 weeks. Stented grafts were associated with diminished IMHR and PCNA+ content at both 4 and 8 weeks (P < 0.05). PDGF+ content was similar among control and stented grafts at 4 weeks, while lower in stented grafts at 8 weeks (P < 0.05). At the distal anastomosis, a correlation between PDGF secretion and Actin+ cell content was observed in control grafts at 4 (r = 0.74) and 8 (r = -0.56) weeks. Cell proliferation was associated with PDGF content in 4-week intraluminal and 8-week control grafts (P < 0.05). Changes in IMHR were not the result of differential PDGF secretion. Intraluminal location attenuates intimal hyperplasia in PTFE grafts. The reduced intimal hyperplasia and improved healing of endoluminal grafts could not be attributed to lower PDGF content alone.

Effect of anesthetic technique on cardiac morbidity following carotid artery surgery

PURPOSE

To investigate the effect of anesthetic technique on cardiac morbidity after carotid artery surgery.

PATIENTS AND METHODS

From 1991 to 1994, 266 consecutive carotid endarterectomies were performed under local/regional (n=140) or general anesthesia (n=126). The effects of anesthetic technique on postoperative adverse cardiac events were assessed retrospectively.

RESULTS

Preoperative cardiac testing was performed in all patients undergoing general or local/regional anesthesia. Medical characteristics were similar among patients in both groups. Forty-seven adverse cardiac events (4 myocardial infarction, 9 congestive heart failure, 7 angina, and 27 new ventricular dysrhythmias) occurred postoperatively in 38 patients (14.3%). There were no deaths. The relative risks of general anesthesia for dysrhythmias, myocardial infarction, angina, congestive heart failure, and total adverse cardiac events were 2.22, 0.37, 0.83, 1.38, and 1.5, respectively. The only statistically significant differential was the increased risk of postoperative dysrhythmias after general anesthesia (P<0.03).

CONCLUSIONS

Major cardiac morbidity following carotid endarterectomy is independent of anesthetic technique.

Role of dipyridamole myocardial scintigraphy in carotid artery surgery

BACKGROUND

Absence of cardiac symptoms is not a valid indicator of low cardiac risk in the sedentary patient who is being considered for vascular surgery. Invasive methods of cardiac assessment in such patients are associated with risk and are expensive. This study was carried out to evaluate the utility of pre-operative cardiac risk stratification with dipyridamole myocardial scintigraphy (DMS), in patients to undergo carotid artery surgery.

STUDY DESIGN

From 1991 to 1994, 174 of 266 carotid endarterectomy patients underwent preoperative DMS. The ability of clinical factors and DMS to predict postoperative cardiac morbidity was assessed retrospectively in a nonrandomized fashion.

RESULTS

Forty-seven adverse cardiac events (deaths = 0, myocardial infarction (MI) = 4, congestive heart failure (CHF) = 9, angina = 7, and new dysrhythmias = 27) occurred in 38 (14.3 percent) of 266 patients. Results of DMS were 73 percent normal, 10.3 percent fixed defect, and 16.7 percent reversible defect examinations. Sensitivity and specificity of DMS was 32 and 74 percent for total cardiac morbidity, and 50 and 74 percent for MI. The positive predictive value of DMS for MI, dysrhythmias, CHF, angina, and all cardiac events was 4, 11, 9, zero, and 23 percent, respectively. Negative predictive values were 98, 91, 98, 95, and 82 percent, respectively. Preoperative histories of MI and chest pain were significant independent predictors of adverse cardiac outcomes (p < 0.05) while age greater than 70 years, smoking, hypertension, diabetes mellitus, preoperative arrhythmias, and DMS were not.

CONCLUSIONS

Dipyridamole myocardial scintigraphy is an ineffective predictor of adverse cardiac events in patients being evaluated for carotid artery surgery and its routine use is not justified.

Vertebrobasilar syndrome associated with subclavian origin of the right internal carotid artery

A case of absence of the right common carotid artery with origin of the external carotid artery from the innominate artery and origin of the internal carotid artery from the right subclavian artery proximal to the right vertebral artery is presented. Atherosclerotic occlusion at the origin of the right subclavian artery and occlusion of the left internal carotid artery resulted in a vertebrobasilar syndrome. Blood flow from the right external carotid reconstituted the right vertebral artery via muscular collateral vessels, moving first retrograde to the subclavian artery and then antegrade through the right internal carotid artery. Symptoms were successfully relieved by transposition of the internal carotid to the external carotid artery. This is the second reported case in the literature and the first to be observed in a clinical setting. The anomaly can easily be explained by embryonic persistence of the right ductus caroticus associated with involution of the right third aortic arch.