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Fluorescent probes are an indispensable tool in the realm of bioimaging technologies, providing valuable insights into the assessment of biomaterial integrity and structural properties. However, incorporating fluorophores into scaffolds made from melt electrowriting (MEW) poses a challenge due to the sustained, elevated temperatures that this processing technique requires. In this context, [n]cycloparaphenylenes ([n]CPPs) serve as excellent fluorophores for MEW processing with the additional benefit of customizable emissions profiles with the same excitation wavelength. Three fluorescent blends are used with distinct [n]CPPs with emission wavelengths of either 466, 494, or 533 nm, identifying 0.01 wt% as the preferred concentration. It is discovered that [n]CPPs disperse well within poly(ε-caprolactone) (PCL) and maintain their fluorescence even after a week of continuous heating at 80 °C. The [n]CPP-PCL blends show no cytotoxicity and support counterstaining with commonly used DAPI (Ex/Em: 359 nm/457 nm), rhodamine- (Ex/Em: 542/565 nm), and fluorescein-tagged (Ex/Em: 490/515 nm) phalloidin stains. Using different color [n]CPP-PCL blends, different MEW fibers are sequentially deposited into a semi-woven scaffold and onto a solution electrospun membrane composed of [8]CPP-PCL as a contrasting substrate for the [10]CPP-PCL MEW fibers. In general, [n]CPPs are potent fluorophores for MEW, providing new imaging options for this technology.

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Artificial tendons may be valuable clinical devices for replacing damaged or missing biological tendons. In this preliminary study, we quantified the effect of polyester-suture-based artificial tendons on movement biomechanics. New Zealand White rabbits underwent surgical replacement of either the Achilles (n = 2) or tibialis cranialis (TC, n = 2) biological tendons with artificial tendons. Once pre-surgery and weekly from 2 to 6 weeks post-surgery, we quantified hindlimb kinematics and ground contact pressures during the stance phase of hopping gait. Post-surgical movement biomechanics were either consistent or improved over time in both groups. However, the Achilles group had greater overall biomechanical and muscle deficits than the TC group. In the TC group, at 6 weeks post-surgery, foot angles were about 10° greater than those in healthy controls during the first 30 % of stance. At 6 weeks post-surgery, the Achilles group exhibited lesser (i.e., more dorsiflexed) ankle angles (minimum angle = 31.5 ± 9.4°) and vertical ground reaction forces (37.4 ± 2.6 %BW) during stance than those in healthy controls (65.0 ± 11.2° and 50.2 ± 8.3 %BW, respectively). Future studies are needed to quantify long-term biomechanical function with artificial tendons, the effect of artificial tendons on muscle function and structure, and the effect of formal rehabilitation.

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Humans and mice have the ability to regenerate the distal digit tip, the terminal phalanx (P3) in response to amputation. What distinguishes P3 regeneration from regenerative failure is formation of the blastema, a proliferative structure that undergoes morphogenesis to regenerate the amputated tissues. P3 regeneration is characterised by the phases of inflammation, tissue histolysis and expansive bone degradation with simultaneous blastema formation, wound closure and finally blastemal differentiation to restore the amputated structures. While each regenerating digit faithfully progresses through all phases of regeneration, phase progression has traditionally been delineated by time, that is, days postamputation (DPA), yet there is widespread variability in the timing of the individual phases. To diminish variability between digits during tissue histolysis and blastema formation, we have established an in-vivo method using microcomputed tomography (micro CT) scanning to identify five distinct stages of the early regeneration response based on anatomical changes of the digit stump. We report that categorising the initial phases of digit regeneration by stage rather than time greatly diminishes the variability between digits with respect to changes in bone volume and length. Also, stages correlate with the levels of cell proliferation, osteoclast recruitment and osteoprogenitor cell recruitment. Importantly, micro CT staging provides a means to estimate open versus closed digit wounds. We demonstrate two spatially distinct and stage specific bone repair/regeneration responses that occur during P3 regeneration. Collectively, these studies showcase the utility of micro CT imaging to infer the composition of radiolucent soft tissues during P3 blastema formation. Specifically, the staging system identifies the onset of cell proliferation, osteoclastogenesis, osteoprogenitor recruitment, the spatial initiation of de novo bone formation and epidermal closure.

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Prosthetic limbs that are completely implanted within skin (i.e., endoprostheses) could permit direct, physical muscle-prosthesis attachment to restore more natural sensorimotor function to people with amputation. The objective of our study was to test, in a rabbit model, the feasibility of replacing the lost foot after hindlimb transtibial amputation by implanting a novel rigid foot-ankle endoprosthesis that is fully covered with skin. We first conducted a pilot, non-survival surgery in two rabbits to determine the maximum size of the skin flap that could be made from the biological foot-ankle. The skin flap size was used to determine the dimensions of the endoprosthesis foot segment. Rigid foot-ankle endoprosthesis prototypes were successfully implanted in three rabbits. The skin incisions healed over a period of approximately 1 month after surgery, with extensive fur regrowth by the pre-defined study endpoint of approximately 2 months post surgery. Upon gross inspection, the skin surrounding the endoprosthesis appeared normal, but a substantial subdermal fibrous capsule had formed around the endoprosthesis. Histology indicated that the structure and thickness of the skin layers (epidermis and dermis) were similar between the operated and non-operated limbs. A layer of subdermal connective tissue representing the fibrous capsule surrounded the endoprosthesis. In the operated limb of one rabbit, the subdermal connective tissue layer was approximately twice as thick as the skin on the medial (skin = 0.43 mm, subdermal = 0.84 mm), ventral (skin = 0.80 mm, subdermal = 1.47 mm), and lateral (skin = 0.76 mm, subdermal = 1.42 mm) aspects of the endoprosthesis. Our results successfully demonstrated the feasibility of implanting a fully skin-covered rigid foot-ankle endoprosthesis to replace the lost tibia-foot segment of the lower limb. Concerns include the fibrotic capsule which could limit the range of motion of jointed endoprostheses. Future studies include testing of endoprosthetics, as well as materials and pharmacologic agents that may suppress fibrous encapsulation.

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Though the rabbit is a common animal model in musculoskeletal research, there are very limited data reported on healthy rabbit biomechanics. Our objective was to quantify the normative hindlimb biomechanics (kinematics and kinetics) of six New Zealand White rabbits (three male, three female) during the stance phase of gait. We measured biomechanics by synchronously recording sagittal plane motion and ground contact pressure using a video camera and pressure-sensitive mat, respectively. Both foot angle (i.e., angle between foot and ground) and ankle angle curves were unimodal. The maximum ankle dorsiflexion angle was 66.4 ± 13.4° (mean ± standard deviation across rabbits) and occurred at 38% stance, while the maximum ankle plantarflexion angle was 137.2 ± 4.8° at toe-off (neutral ankle angle = 90 degrees). Minimum and maximum foot angles were 17.2 ± 6.3° at 10% stance and 123.3 ± 3.6° at toe-off, respectively. The maximum peak plantar pressure and plantar contact area were 21.7 ± 4.6% BW/cm2 and 7.4 ± 0.8 cm2 respectively. The maximum net vertical ground reaction force and vertical impulse, averaged across rabbits, were 44.0 ± 10.6% BW and 10.9 ± 3.7% BW∙s, respectively. Stance duration (0.40 ± 0.15 s) was statistically significantly correlated (p < 0.05) with vertical impulse (Spearman's ρ = 0.76), minimum foot angle (ρ = -0.58), plantar contact length (ρ = 0.52), maximum foot angle (ρ = 0.41), and minimum foot angle (ρ = -0.30). Our study confirmed that rabbits exhibit a digitigrade gait pattern during locomotion. Future studies can reference our data to quantify the extent to which clinical interventions affect rabbit biomechanics.

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OBJECTIVES: To analyze the characteristics and outcome of Impella mechanical circulatory support (MCS) for Takotsubo syndrome (TS) with cardiogenic shock. BACKGROUND: TS is an acute heart failure syndrome characterized by transient severe reduction of left ventricular (LV) systolic function, with cardiogenic shock occurring in around 10% of patients. Since inotropes should be avoided due to their role in TS pathogenesis and aggravation of LV outflow tract obstruction, the use of MCS as treatment is a viable treatment option, however, studies are lacking. METHODS: The catheter-based ventricular assist device (cVAD) registry and local MCS databases were screened for TS patients with cardiogenic shock (TS-CS) supported with an Impella percutaneous ventricular assist device (pVAD). Patient and treatment characteristics and in-hospital outcomes were retrospectively analyzed. RESULTS: At 10 US and European centers, 16 TS-CS patients supported with an Impella pVAD were identified between December 2013 and May 2018 (mean age, 61.8 ± 15.5 years; 87.5% women). LV ejection fraction (LVEF) at presentation was severely reduced (mean, 19.4 ± 8.3%). Prior to MCS, 13 patients (81.3%) were mechanically ventilated, 4 patients (25.0%) had been resuscitated, and mean serum lactate was 4.7 ± 3.5 mmol/L. Mean duration of Impella support was 1.9 ± 1.0 days (range, 1-4 days). Thirteen patients (81.3%) survived to discharge, and all survivors experienced cardiac recovery with significant improvement of LVEF at discharge compared to baseline (20.4 ± 8.8 vs. 52.9 ± 12.0, P < 0.001). CONCLUSIONS: This is the first series of TS-CS patients supported with an Impella pVAD. Mortality was low, and LV systolic function recovered in all survivors. Prospective studies of Impella support in this special condition are warranted.

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The use of machine learning (ML) has become more widespread in many areas of consumer financial services, including credit underwriting and pricing of loans. ML's ability to automatically learn nonlinearities and interactions in training data is perceived to facilitate faster and more accurate credit decisions, and ML is now a viable challenger to traditional credit modeling methodologies. In this mini review, we further the discussion of ML in consumer finance by proposing uniform definitions of key ML and legal concepts related to discrimination and interpretability. We use the United States legal and regulatory environment as a foundation to add critical context to the broader discussion of relevant, substantial, and novel ML methodologies in credit underwriting, and we review numerous strategies to mitigate the many potential adverse implications of ML in consumer finance.

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Previous prostheses for replacing a missing limb following amputation must be worn externally on the body. This limits the extent to which prostheses could physically interface with biological tissues, such as muscles, to enhance functional recovery. The objectives of our study were to (1) test the feasibility of implanting a limb prosthesis, or endoprosthesis, entirely within living skin at the distal end of a residual limb, and (2) identify effective surgical and post-surgical care approaches for implanting endoprostheses in a rabbit model of hindlimb amputation. We iteratively designed, fabricated, and implanted unjointed endoprosthesis prototypes in six New Zealand White rabbits following amputation. In the first three rabbits, the skin failed to heal due to ishemia and dehiscence along the sutured incision. The skin of the final three subsequent rabbits successfully healed over the endoprotheses. Factors that contributed to successful outcomes included modifying the surgical incision to preserve vasculature; increasing the radii size on the endoprostheses to reduce skin stress; collecting radiographs pre-surgery to match the bone pin size to the medullary canal size; and ensuring post-operative bandage integrity. These results will support future work to test jointed endoprostheses that can be attached to muscles.

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Wearable, mechanically passive (i.e. spring-powered) exoskeletons may be more practical and affordable than active, motorized exoskeletons for providing continuous, home-based, antigravity movement assistance for people with shoulder disability. However, the biomechanical moment due to gravity is a nonlinear function of shoulder elevation angle and, thus, challenging to counteract proportionally across the shoulder elevation range of motion with a spring alone. We designed, fabricated, and tested an integrated spring-cam-wheel system that can generate a nonlinear moment to proportionally compensate for the expected antigravity moment at the shoulder. We then incorporated the proposed system in a benchtop model and a novel wearable passive cable-driven exoskeleton that was intended to counteract half of the gravitational moment during shoulder elevation movements. The rotational moment measured from the benchtop model closely matched the theoretical moment during simulated positive shoulder elevation. However, a larger moment (up to 12.5% larger) was required during simulated negative shoulder elevation to stretch the spring to its initial length due to spring hysteresis and friction losses. The wearable exoskeleton prototype was qualitatively tested for assisting shoulder elevation movements; we identified several aspects of the prototype design that need to be improved before further testing on human participants. In future studies, we will quantitatively evaluate human kinematics and neuromuscular coordination with the exoskeleton to determine its suitability for assisting patients with shoulder disability.

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Passive shoulder exoskeletons, which provide continuous anti-gravitational force at the shoulder, could assist with dynamic shoulder elevation movements involved in activities of daily living and rehabilitation exercises. However, prior biomechanical studies of these exoskeletons primarily focused on static overhead tasks. In this study, we evaluated how continuous passive anti-gravity assistance affects able-bodied neuromuscular activity and shoulder kinematics during dynamic and static phases of shoulder elevation movements. Subjects, seated upright, elevated the shoulder from a rest posture (arm relaxed at the side) to a target shoulder elevation angle of 90°. Subjects performed the movement in the frontal (abduction) and scapular (scaption) planes with and without passive anti-gravity assistance. Muscles that contribute to positive shoulder elevation, based on their reported moment arms, had significantly lower muscle activations with assistance during both dynamic and static elevation. Muscles that contribute to negative shoulder elevation, which can decelerate the shoulder during dynamic shoulder elevation, were not significantly different between assistance conditions. This may be partly explained by the trend of subjects to reduce their maximum angular decelerations near the target to offset the positive shoulder elevation moment due to the anti-gravity assistance. Our results suggest that passive anti-gravity assistance could reduce the muscle activations needed to perform dynamic movements. Consequently, the anti-gravity assistance of passive shoulder exoskeletons may enhance motor function and reduce muscle and joint loads for both able-bodied and disabled users.

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Wearable passive (ie, spring powered) shoulder exoskeletons could reduce muscle output during motor tasks to help prevent or treat shoulder musculoskeletal disorders. However, most wearable passive shoulder exoskeletons have been designed and evaluated for static tasks, so it is unclear how they affect muscle output during dynamic tasks. The authors used a musculoskeletal model and Computed Muscle Control optimization to estimate muscle output with and without a wearable passive shoulder exoskeleton during 2 simulated dynamic tasks: abduction and upward reach. To an existing upper extremity musculoskeletal model, the authors added an exoskeleton model with 3-dimensional representations of the exoskeleton components, including a spring, cam wheel, force-transmitting shoulder cable, and wrapping surfaces that permitted the shoulder cable to wrap over the shoulder. The exoskeleton reduced net muscle-generated moments in positive shoulder elevation by 28% and 62% during the abduction and upward reach, respectively. However, muscle outputs (joint moments and muscle effort) were higher with the exoskeleton than without at some points of the movement. Muscle output was higher with the exoskeleton because the exoskeleton moment opposed the muscle-generated moment in some postures. The results of this study highlight the importance of evaluating muscle output for passive exoskeletons designed to support dynamic movements to ensure that the exoskeletons assist, rather than impede, movement.

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The purpose of this study was to evaluate the radiographic and clinical outcomes of isolated talonavicular arthrodesis in the treatment of the flexible pes valgus foot type. Retrospectively, 51 consecutive isolated talonavicular arthrodeses in 41 patients were evaluated. The mean patient age was 47 (range 9 to 72) years, and the mean follow-up duration was 43.3 (range 11 to 113) months. The mean 10-cm categorical pain score before the surgery was 7.60 +/- 2.37, and this improved to 1.90 +/- 2.38 postoperatively, and this difference was statistically significant (P < .001). We also measured the preoperative and postoperative percent of talar uncovering, calcaneocuboid angle, Kite's angle, talar dome height, calcaneal inclination angle, and Meary's angle, and observed statistically significant (P < .001) improvements in all of these. Fifty-one (100%) of the cases progressed to radiographic osseous union, although 2 (3.92%) of the cases were considered delayed unions. Moreover, 4 (7.84%) of the cases displayed juxta-articular arthrosis postoperatively, and 2 (3.9%) cases developed transfer pain to the lateral column. The authors concluded that isolated talonavicular arthrodesis is a safe and effective procedure for the treatment of painful pes valgus deformity.

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UNLABELLED: Heat is generated whenever osteotomies are created, Kirschner wires are inserted, holes are drilled, and when bone is reduced with a burr. Although previous investigators have determined the combination of time and temperature necessary to cause bone injury, to our knowledge, no one has yet specifically studied whether the heat generated when osteotomies are performed in the foot reaches sufficient levels to damage osseous tissue. Toward that end, the authors designed an experiment to measure the change in cadaveric first metatarsal temperature, and the time associated with the rise and fall of the bone temperature, in response to osteotomies performed with and without concomitant saline solution irrigation of the saw blade. The study was conducted on matched pairs (contralateral limbs) of cadaveric bone, with one side being irrigated with normal saline solution and the other side being osteotomized without saline solution irrigation. Osteotomies were created dorsally and plantarly at 3 sites in the first metatarsal specimens, specifically at the head, mid-diaphysis, and base; and a total of 112 osteotomies were included in the analyses. Regardless of whether saline solution irrigation was used, none of the bone specimens reached a temperature known to be associated with thermal injury during osteotomy. The use of saline solution irrigation did, however, provide a reduction in peak bone temperature during osteotomy, and the duration of sustained temperature elevation was also shortened with the use of irrigation. LEVEL OF CLINICAL EVIDENCE: 5.

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We screened a library of 117 bisphosphonates for antibacterial activity against Escherichia coli. The most potent growth inhibitors where N-[methyl(4-phenylalkyl)]-3-aminopropyl-1-hydroxy-1,1-bisphosphonates, known potent bone resorption inhibitors, and there was a generally good correlation between cell growth inhibition and E. coli farnesyl diphosphate synthase (FPPS) inhibition. However, some potent FPPS inhibitors had no activity in cell growth inhibition, and based on the result of Catalyst pharmacophore modeling, this could be attributed to the requirement of a large hydrophobic feature for cellular activity (due most likely to transport). The activity of the most potent compound, N-[methyl(4-phenylbutyl)]-3-aminopropyl-1-hydroxy-1,1-bisphosphonate (13), was strongly potentiated by the drug fosmidomycin. The transcription profiles for 13 or fosmidomycin alone were different from those found with carbenicillin or ciprofloxacin alone, but there were many similarities between the combination (13-fosmidomycin) and carbenicillin or ciprofloxacin, reflecting the more potent bactericidal activity of the drug combination on bacterial growth.

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BACKGROUND: The filter-based FilterWire EX (Boston Scientific, Natick, MA) embolic protection system and the GuardWire (Medtronic, Santa Rosa, CA) balloon occlusion and aspiration device have been previously shown to reduce periprocedural complication rates of percutaneous coronary intervention for saphenous vein graft (SVG) disease and are considered the standard of care in this setting. The late clinical course after treatment with these devices has not been reported. METHODS: In the FIRE trial, 651 patients undergoing SVG intervention were randomized to either the FilterWire EX or GuardWire. Six-month rates of the primary end point (composite major adverse cardiac events [MACE]) and its components (death, myocardial infarction [MI], or target vessel revascularization) were studied. RESULTS: MACE at 30 days occurred in 9.9% of patients randomized to the FilterWire EX compared with 11.6% with the GuardWire, P = .53. By 6 months, MACE had increased to 19.3% and 21.9% in FilterWire EX and GuardWire groups, respectively, (relative risk 0.88, 95% CI 0.65-1.19; P = .44). All-cause 6-month mortality in the entire population was 3.5% (3.0% with FilterWire EX vs 4.1% with GuardWire, P = .53, with all deaths occurring after hospital discharge). MI occurred in 12.0% of patients at 6 months (12.1% vs 11.9% with the FilterWire EX and GuardWire, respectively, P = .99), and target vessel revascularization was required in 9.1% (8.2% vs 10.0%, respectively, P = .42). CONCLUSIONS: SVG intervention with the FilterWire EX and GuardWire distal protection devices resulted in similar outcomes at 6 months, although the clinical course after hospital discharge was not benign, with significant rates of death, MI, and repeat intervention.

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BACKGROUND: Mechanical closure of percutaneous femoral arteriotomies following catheter based procedures remains problematic. METHODS: The EVS closure device is the first to utilize a staple to effect arteriotomy closure and was compared to manual compression following sheath removal in a 362 patient randomized (2:1 to device) multicenter trial. As pre-specified, one half of the patients underwent coronary intervention. RESULTS: Time to hemostasis was significantly reduced in the EVS group for both diagnostic (3.3 +/- 2.6 vs. 19.3 +/- 5.7 minutes; p < 0.001) and interventional procedures (5.5 +/- 5.1 vs. 22.3 +/- 9.9 minutes; p < 0.0001). Time to ambulation was similarly reduced in the EVS group following diagnostic (2.4 +/- 3.3 vs. 6.0 +/- 5.2 hours; p < 0.001) and interventional procedures (3.4 +/- 4.5 vs. 7.6 +/- 7.0 hours; p < 0.001). The incidence of major complications was similar between the EVS and manual compression groups at discharge (0.4% vs. 1.7%; p = NS) and at 30 day follow-up (0.4% vs. 2.5%; p = NS). CONCLUSION: Compared to manual compression, the EVS device provides a safe and effective method of femoral artery closure.

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AIMS: This study assessed safety and efficacy of a third-generation distal protection device, MedNova CardioShield Bare Wire Myocardial Protection System, for treating Saphenous Vein Graft (SVG) disease.Treatment of SVG disease remains difficult, with increased adverse cardiac events (MACE) primarily manifested as no reflow and periprocedural infarction. Even with approved embolic protection devices, 30-day MACE rates are approximately 10%. METHODS AND RESULTS: A multicentre randomized clinical trial evaluated a third-generation distal protection device MedNova CardioShield vs Percusurge GuardWire in 652 patients undergoing treatment of SVG disease, using a primary endpoint of 30-day death, Q-wave, non-Q-wave infarction, or target vessel revascularisation (MACE).The primary endpoint occurred in 11.4% with CardioShield vs 9.1% with GuardWire (P=.37). Intention-to-treat analysis showed a strong trend for noninferiority (P=.057). Secondary modified intention-to-treat analysis including only patients receiving treatment device and no protocol deviation (defined as treatment of another lesion not using embolic protection) supported noninferiority of CardioShield (P=.022). CONCLUSION: Analysis of outcomes of treatment strategies for SVG disease is difficult. In this trial, final results depended on whether a patient actually received the device according to protocol. With 30-day MACE as primary endpoint, CardioShield was not demonstrated to be noninferior to GuardWire.

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CONTEXT: Compared with bare metal stents, drug-eluting stents reduce restenosis in noncomplex lesions. The utility of drug-eluting stents has not been evaluated in more difficult stenoses. OBJECTIVE: To investigate the safety and efficacy of the polymer-based, slow-release paclitaxel-eluting stent in a patient population with more complex lesions than previously studied. DESIGN, SETTING, AND PATIENTS: Prospective, placebo-controlled, double-blind, multicenter randomized trial conducted from February 2003 to March 2004 at 66 academic and community-based institutions with 1156 patients who underwent stent implantation in a single coronary artery stenosis (vessel diameter, 2.25-4.0 mm; lesion length, 10-46 mm), including 664 patients (57.4%) with complex or previously unstudied lesions (requiring 2.25-mm, 4.0-mm, and/or multiple stents) and 9-month clinical and angiographic follow-up. INTERVENTIONS: Patients were randomly assigned to receive 1 or more bare metal stents (n = 579) or identical-appearing paclitaxel-eluting stents (n = 577). MAIN OUTCOME MEASURE: Ischemia-driven target vessel revascularization at 9 months. RESULTS: Baseline characteristics were well matched. Diabetes was present in 31% of patients. The mean (SD) reference vessel diameter was 2.69 (0.57) mm, the reference lesion length was 17.2 (9.2) mm, and 78% of lesions were type B2/C. A mean (SD) of 1.38 (0.58) stents (total mean [SD] length, 28.4 [13.1] mm) were implanted per lesion; 33% of lesions required multiple stents. Stents that were 2.25 mm and 4.0 mm in diameter were used in 18% and 17% of lesions, respectively. Compared with bare metal stents, paclitaxel-eluting stents reduced the 9-month rate of target lesion revascularization from 15.7% to 8.6% (P<.001) and target vessel revascularization from 17.3% to 12.1% (P = .02). Similar rates were observed for cardiac death or myocardial infarction (5.5% for bare metal stent group vs 5.7% for paclitaxel-eluting stent group) and stent thrombosis (0.7% in both groups). Angiographic restenosis was reduced from 33.9% to 18.9% in the entire study cohort (P<.001), including among patients receiving 2.25-mm stents (49.4% vs 31.2%; P = .01), 4.0-mm stents (14.4% vs 3.5%; P = .02), and multiple stents (57.8% vs 27.2%; P<.001). CONCLUSION: Compared with a bare metal stent, implantation of the paclitaxel-eluting stent in a patient population with complex lesions effectively reduces clinical and angiographic restenosis.

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BACKGROUND: Predictors of complications in peripheral percutaneous interventions (PPI) with bivalirudin as a base anticoagulant have not yet been defined. The Angiomax Peripheral Procedure Registry of Vascular Events (APPROVE) offers a unique opportunity to analyze predictors of complications with bivalirudin in PPI. METHODS: APPROVE was a prospective, open-label, multi-center clinical trial that assessed the feasibility of bivalirudin in renal, iliac and femoral interventions. Bivalirudin was administered intravenously at a dose of 0.75 mg per kg bolus followed by an infusion of 1.75 mg per kg per hour for the duration of the procedure. Glycoprotein (GP) IIb-IIIa inhibitors were permitted at the discretion of the treating physician. Multiple independent variables were included in a Logistic Regression model to determine predictors of the combined endpoints of ischemic (death, amputation, unplanned urgent revascularization at the treated site, myocardial infarction) and major bleeding or major bleeding alone, assessed during hospitalization and at 30 days. RESULTS: Predictors of in-hospital ischemic and major bleed events were congestive heart failure (p = 0.0173) and exchanges to larger sheath size (ELS) (p = 0.0045). The strongest predictor of major bleeding alone at discharge (p = 0.0041) and at 30 days (p = 0.0016) was the number of ELS. Also, female gender (p = 0.08) and low weight (stratified by gender with < 80 kg versus > 92 kg for males and < 62 kg versus > 77 kg for females) (p = 0.096) showed a trend toward predicting major bleeding at 30 days. Of 505 patients in APPROVE, 26 patients required more than one sheath exchange. Of these, 24 were ELS. Despite this small number, these patients accounted for most of the major bleeding events that occurred (11.5% versus 1.7% in-hospital bleeding for the patients with ELS versus single sheath use respectively, and 15.4% versus 3.1% for 30-day bleeding). GP IIb-IIIa inhibitors (n = 22) use and thrombotic lesions (3%) were not predictors of ischemic and/or bleeding complications. CONCLUSION: ELS during PPI is a strong predictor of bleeding events when bivalirudin is used as a base anticoagulant. Female gender and low weight also tend to contribute to major bleeding.

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