Digital light 4D printing of bioresorbable shape memory elastomers for personalized biomedical implantation.

Four-dimensional (4D) printing unlocks new potentials for personalized biomedical implantation, but still with hurdles of lacking suitable materials. Herein, we demonstrate a bioresorbable shape memory elastomer (SME) with high elasticity at both below and above its phase transition temperature (Ttrans). This SME can be digital light 3D printed by co-polymerizing glycerol dodecanoate acrylate prepolymer (pre-PGDA) with acrylic acid monomer to form crosslinked Poly(glycerol dodecanoate acrylate) (PGDA)-Polyacrylic acid (PAA), or PGDA-PAA network. The printed complex, free-standing 3D structures with high-resolution features exhibit shape programming properties at a physiological temperature. By tuning the pre-PGDA weight ratios between 55 wt% and 70 wt%, Ttrans varies between 39.2 and 47.2 ℃ while Young's moduli (E) range 40-170 MPa below Ttrans with fractural strain (εf) of 170 %-200 %. Above Ttrans, E drops to 1-1.82 MPa which is close to those of soft tissue. Strikingly, εf of 130-180 % is still maintained. In vitro biocompatibility test on the material shows > 90 % cell proliferation and great cell attachment. In vivo vascular grafting trials underline the geometrical and mechanical adaptability of these 4D printed constructs in regenerating the aorta tissue. Biodegradation of the implants shows the possibility of their full replacement by natural tissue over time. To highlight its potential for personalized medicine, a patient-specific left atrial appendage (LAA) occluder was printed and implanted endovascularly into an in vitro heart model. STATEMENT OF SIGNIFICANCE: 4D printed shape-memory elastomer (SME) implants particularly designed and manufactured for a patient are greatly sought-after in minimally invasive surgery (MIS). Traditional shape-memory polymers used in these implants often suffer from issues like unsuitable transition temperatures, poor biocompatibility, limited 3D design complexity, and low toughness, making them unsuitable for MIS. Our new SME, with an adjustable transition temperature and enhanced toughness, is both biocompatible and naturally degradable, particularly in cardiovascular contexts. This allows implants, like biomedical scaffolds, to be programmed at room temperature and then adapt to the body's physiological conditions post-implantation. Our studies, including in vivo vascular grafts and in vitro device implantation, highlight the SME's effectiveness in aortic tissue regeneration and its promising applications in MIS.

Thermal Ablation in the Liver: Heat versus Cold-What Is the Role of Cryoablation?

Cryoablation is commonly used in the kidney, lung, breast, and soft tissue, but is an uncommon choice in the liver where radiofrequency ablation (RFA) and microwave ablation (MWA) predominate. This is in part for historical reasons due to serious complications that occurred with open hepatic cryoablation using early technology. More current technology combined with image-guided percutaneous approaches has ameliorated these issues and allowed cryoablation to become a safe and effective thermal ablation modality for treating liver tumors. Cryoablation has several advantages over RFA and MWA including the ability to visualize the ice ball, minimal procedural pain, and strong immunomodulatory effects. This article will review the current literature on cryoablation of primary and secondary liver tumors, with a focus on efficacy, safety, and immunogenic potential. Clinical scenarios when it may be more beneficial to use cryoablation over heat-based ablation in the liver, as well as directions for future research, will also be discussed.

Splenic Artery Embolization for Treatment of Iatrogenic Kasabach-Merritt Phenomenon Following Failed Endovascular Splenic Artery Aneurysm Repair.

Stent grafts are utilized to treat and exclude visceral arterial aneurysms while preserving flow through the vessel. Stent-associated thrombocytopenia is a rare complication not typically seen with modern stents. The following case describes the clinical presentation of stent kinking and consumptive coagulopathy. Stent-associated microangiopathic hemolytic anemia was inferred from protracted workup and exclusion of alternative diagnoses. Despite the risk of arterial puncture in the setting of profound thrombocytopenia, the patient was successfully treated with stent embolization with near immediate rebound in platelet count. This case report documents the presentation of rare stent-associated thrombocytopenia leading to challenging diagnostic evaluation and necessitating high-risk intervention.

Recanalization and Reconstruction of a Chronically Occluded Inferior Vena Cava Through an Existing Transjugular Intrahepatic Portosystemic Shunt in the Setting of Budd-Chiari Syndrome.

Budd-Chiari syndrome (BCS) results from the occlusion or flow reduction in the hepatic veins or inferior vena cava and can be treated with transjugular intrahepatic portosystemic shunt when hepatic vein recanalization fails.1-3 Hypercoagulable patients with primary BCS are predisposed to development of new areas of thrombosis within the TIPS shunt or IVC. This case details a patient with BCS, pre-existing TIPS extending to the right atrium, and chronic retrohepatic IVC thrombosis who underwent sharp recanalization of the IVC with stenting into the TIPS stent bridging the patient until his subsequent hepatic transplantation.

Successful Percutaneous Transcatheter Closure of a Common Femoral Artery Pseudoaneurysm With Use of MicroVascular Plug Despite Continued Catheter-Directed Thrombolysis.

Common femoral artery pseudoaneurysm is a known complication of percutaneous vascular access. Treatment options include surgical repair of the pseudoaneurysm or endovascular methods such as ultrasound-guided compression and direct thrombin injection into the pseudoaneurysm sac. Treatment of pseudoaneurysm is more challenging when a patient is undergoing concurrent catheter-directed or systemic thrombolytic therapy. This is a case report of endovascular treatment of an iatrogenic pseudoaneurysm of common femoral artery in a patient receiving concurrent catheter-directed thrombolytic therapy. This was performed successfully by precise deployment of a MicroVascular Plug into the pseudoaneurysm neck with immediate closure of pseudoaneurysm. Midterm follow-up confirmed sustained exclusion of the pseudoaneurysm sac with continued patency of the treated femoral artery.

Recurrent Ectopic Variceal Bleed After Pancreas Transplantation With No Portal Hypertension: Case Report and Outcomes of Endovascular Onyx Embolization.

A 57-year-old male presented with intermittent gastrointestinal bleeding (GIB) 1 year after a successful simultaneous pancreas and kidney transplant. No source could be found after 5 tagged red blood cell studies, 3 computed tomographies (CTs), 7 endoscopies, and 4 catheter angiograms. Review of CTs showed pathologically enlarged superior mesenteric vein branches near a jejunal segment near pancreas graft. Transhepatic superior mesenteric venogram showed varicosities near jejunum, which were obliterated with ethylene vinyl alcohol (Onyx). Follow-up CTs confirmed complete obliteration, but he had more GIBs and eventually underwent native jejunal and donor duodenal resection. He has remained GIB-free for 12 months.

CT Fluoroscopic-Guided Coil Localization of Lung Nodules prior to Video-Assisted Thoracoscopic Surgical Resection Reduces Complications Compared to Hook Wire Localization.

PURPOSE: To compare the safety and efficacy of hook wire versus microcoil localization of pulmonary nodules prior to video-assisted thoracoscopic resection (VATS). MATERIALS AND METHODS: A retrospective comparative review was conducted of 46 patients (26 hook wire and 20 microcoil) who underwent computed tomography fluoroscopic-guided nodule localizations prior to VATS in a single center between January 2012 and August 2016. Nodule characteristics, procedural details, clinical outcomes, and pathologic findings were collected. Baseline characteristics and lung nodule distribution were not significantly different between the 2 groups. Nodule sizes ranged from 2 mm to 28 mm and were similar between groups. Twenty-nine patients (63%) were male, with mean (standard deviation) age of 61 (11) years. Adverse events were classified using standard criteria. Patients were followed for up to 90 days, and the clinical outcomes were compared. RESULTS: Successful resection of nodules was achieved in all patients. Twelve cases of displacement of the hook wire were observed compared to only 1 in the coil group (P < .01). The total complication rate was lower in the coil group (25% vs 54%, P = .04). Two patients required transition to thoracotomy in the hook wire group, compared to none in the coil group. Median blood loss was similar in both groups (median loss, 20-22 mL). One patient had positive margins in the hook wire group. There was a nonsignificant trend toward longer hospital stay and higher major complication rates after hook wire localization (P = .4). CONCLUSIONS: Pulmonary nodule localization with coils prior to VATS resection demonstrated fewer displacements and fewer perioperative complications compared to hook wires.

A new heat source for thermochemical ablation based on redox chemistry: initial studies using permanganate.

PURPOSE: To evaluate exothermic permanganate redox chemistry for utility in tumour ablation. MATERIALS AND METHODS: Sodium permanganate (1-3 mL, 1 or 2 M) and glycerol (1 mL, 1 M) were injected in triplicate into a beaker using three injection orders: (1) simultaneous, (2) glycerol injection then permanganate injection, (3) permanganate injection then glycerol injection. Selected experiments were repeated with glucose, sucrose, dextrin, maltodextrin, different polysaccharides, and polyvinyl alcohol as substrates. Simultaneous injections of permanganate (0.5 and 1 mL, 2 M) and glucose (1 mL, 1 M) into explanted porcine muscle were also performed. Temperatures were recorded with a thermocouple probe or an infrared camera. RESULTS: With optimal conditions of 2 M permanganate and 1 M glycerol at 1 mL each, an average maximum temperature of 97.4 degrees C was obtained for all three injection orders. When glucose and sucrose were used as the substrates, similar temperatures were achieved but at different rates. Dextrin and maltodextrin (180 g/L) led to maximum temperatures of 42.5 degrees and 51.1 degrees C respectively when simultaneously injected with permanganate (1 mL, 2 M). Polysaccharides and polyvinyl alcohols under the same conditions resulted in a minimal temperature increase. Intramuscular injections of glucose (0.5 mL, 1 M) and permanganate (0.5 mL, 2 M) reached an average temperature of 76.5 degrees C at the lesion site. CONCLUSIONS: The permanganate redox reaction is a powerful system with potential to reach tumouricidal temperatures. The reagent volumes, concentrations, injection order, and substrate choice allow a measure of control over the reaction.