Image-Based Evaluation of In Vivo Degradation for Shape-Memory Polymer Polyurethane Foam.

Shape-memory polymer (SMP) polyurethane foams have been applied as embolic devices and implanted in multiple animal models. These materials are oxidatively degradable and it is critical to quantify and characterize the degradation for biocompatibility assessments. An image-based method using high-resolution and magnification scans of histology sections was used to estimate the mass loss of the peripheral and neurovascular embolization devices (PED, NED).

Diffusible contrast-enhanced micro-CT improves visualization of stented vessels.

In this report, we showcase diffusible iodine-based contrast-enhanced computed tomography (DICE-CT) as a method for improving soft tissue visualization and reducing beam hardening artifact within a stented vessel. This technique is commonly used in our pathology lab to image soft tissue specimens with dense metal implants and to ensure reliable morphological analysis through clear delineation of tissue structures. For this report, a porcine right coronary artery with an implanted metal stent was scanned using both conventional and DICE-CT methods.

Microscopic Assessment of Healing and Effectiveness of a Foam-Based Peripheral Occlusion Device.

The IMPEDE Embolization Plug is a catheter-delivered vascular occlusion device that utilizes a porous shape memory polymer foam as a scaffold for thrombus formation and distal coils to anchor the device within the vessel. In this study, we investigated the biological response of porcine arteries to the IMPEDE device by assessing the extent of healing and overall effectiveness in occluding the vessel at 30, 60, and 90 days. Compared to control devices (Amplatzer Vascular Plug and Nester Embolization Coils), the host response to IMPEDE showed increased cellular infiltration (accommodated by the foam scaffold), which led to advanced healing of the initial thrombus to mature collagenous connective tissue (confirmed by transmission electron microscopy (TEM)).

Micro-CT and histopathology methods to assess host response of aneurysms treated with shape memory polymer foam-coated coils versus bare metal coil occlusion devices.

Recent studies utilizing shape memory polymer foams to coat embolizing coils have shown potential benefits over current aneurysm treatments. In the current study utilizing a rabbit-elastase aneurysm model, the performance of test article (foam-coated coil [FCC]) and control (bare platinum coils [BPCs]) devices were compared at 30, 90, and 180 days using micro-CT and histological assessments. The host response was measured by identifying the cells regionally present within the aneurysm, and assessing the degree of residual debris and connective tissue.

A self-cleaning, mechanically robust membrane for minimizing the foreign body reaction: towards extending the lifetime of sub-Q glucose biosensors.

Long-term, subcutaneously implanted continuous glucose biosensors have the potential to improve diabetes management and reduce associated complications. However, the innate foreign body reaction (FBR) both alters the local glucose concentrations in the surrounding tissues and compromises glucose diffusion to the biosensor due to the recruitment of high-metabolizing inflammatory cells and the formation of a dense, collagenous fibrous capsule. Minimizing the FBR has mainly focused on "passively antifouling" materials that reduce initial cellular attachment, including poly(ethylene glycol) (PEG).

Introduction to Currently Applied Device Pathology.

Pathologic evaluation is crucial to the study of medical devices and integral to the Food and Drug Administration and other regulatory entities' assessment of device safety and efficacy. While pathologic analysis is tailored to the type of device, it generally involves at a minimum gross and microscopic evaluation of the medical device and associated tissues. Due to the complex nature of some implanted devices and specific questions posed by sponsors, pathologic evaluation inherently presents many challenges in accurately assessing medical device safety and efficacy.

Method for preclinical pathology evaluation and analysis of cardiovascular implantable electronic device implant sites.

Unlabelled: Cardiovascular implantable electronic devices (CIEDs) typically incorporate leads that directly contact the endocardium. Post-explant pathology evaluation of formalin-fixed CIED lead implant sites and downstream organs (i.e.

Foreign Body Reaction to a Subcutaneously Implanted Self-Cleaning, Thermoresponsive Hydrogel Membrane for Glucose Biosensors.

Towards achieveing a subcutaneously implanted glucose biosensor with long-term functionality, a thermoresponsive membrane previously shown to have potential to house a glucose sensing assay was evaluated herein for its ability to minimize the foriegn body reaction (FBR) and the resulting fibrous capsule. The severity of the FBR proportionally reduces diffusion of glucose to the sensor and hence sensor lifetime. However, efforts to reduce the FBR have largedly focused on anti-fouling materials that passively inhibit cellular attachment, particularly poly(ethylene glycol) (PEG).

Design and verification of a shape memory polymer peripheral occlusion device.

Shape memory polymer foams have been previously investigated for their safety and efficacy in treating a porcine aneurysm model. Their biocompatibility, rapid thrombus formation, and ability for endovascular catheter-based delivery to a variety of vascular beds makes these foams ideal candidates for use in numerous embolic applications, particularly within the peripheral vasculature. This study sought to investigate the material properties, safety, and efficacy of a shape memory polymer peripheral embolization device in vitro.

Comparison of shape memory polymer foam versus bare metal coil treatments in an in vivo porcine sidewall aneurysm model.

The endovascular delivery of platinum alloy bare metal coils has been widely adapted to treat intracranial aneurysms. Despite the widespread clinical use of this technique, numerous suboptimal outcomes are possible. These may include chronic inflammation, low volume filling, coil compaction, and recanalization, all of which can lead to aneurysm recurrence, need for retreatment, and/or potential rupture.

A Method for Creating Artificial Thrombi In Vitro Using a Rotating Mechanical Surface.

Thromboembolism is a common concern in ventricular assist device (VAD) therapy. Precise VAD response to pass-through thromboembolism needs to be studied in a controlled in vitro setting where specific pump parameters (i.e.

Deep Bleeder Acoustic Coagulation (DBAC)-part II: in vivo testing of a research prototype system.

Background: Deep Bleeder Acoustic Coagulation (DBAC) is an ultrasound image-guided high-intensity focused ultrasound (HIFU) method proposed to automatically detect and localize (D&L) and treat deep, bleeding, combat wounds in the limbs of soldiers. A prototype DBAC system consisting of an applicator and control unit was developed for testing on animals. To enhance control, and thus safety, of the ultimate human DBAC autonomous product system, a thermal coagulation strategy that minimized cavitation, boiling, and non-linear behaviors was used.

Heart failure in remission for more than 13 years after removal of a left ventricular assist device.

Mechanical cardiac unloading with use of a left ventricular assist device (LVAD) is associated with substantial improvements in left ventricular function and enables subsequent LVAD explantation in some patients. We describe the case of a 35-year-old man with dilated nonischemic cardiomyopathy who was supported with an LVAD for 9 months. After the device was removed, he led a normal life for 13 years and 4 months.

Comparative pathology of an implantable left atrial pressure sensor.

A left atrial pressure (LAP) monitoring system was developed for guiding the management of patients with heart failure. The LAP sensor is implanted into the left atrium via transseptal catheterization and affixed to the interatrial septum by nitinol anchors. The long-term safety of permanent implantation of the LAP sensor in patients was evaluated based on the comparative pathology in animals.

In vivo response to an implanted shape memory polyurethane foam in a porcine aneurysm model.

Cerebral aneurysms treated by traditional endovascular methods using platinum coils have a tendency to be unstable, either due to chronic inflammation, compaction of coils, or growth of the aneurysm. We propose to use alternate filling methods for the treatment of intracranial aneurysms using polyurethane-based shape memory polymer (SMP) foams. SMP polyurethane foams were surgically implanted in a porcine aneurysm model to determine biocompatibility, localized thrombogenicity, and their ability to serve as a stable filler material within an aneurysm.

A brief review of ventricular assist devices and a recommended protocol for pathology evaluations.

Unlabelled: Heart failure is a leading cause of death in human populations, and as people live longer, it is becoming an increasingly prominent problem. Because of the insufficient numbers of donor hearts, physicians and engineers are turning to mechanical circulatory support in the form of ventricular assist devices (VADs). Their clinical performance and increasing availability of various types, sizes, and functions are increasing VAD recognition.

The effect of otolith malformation on behavior and cortisol levels in juvenile red drum fish (Sciaenops ocellatus).

Captive-raised red drum fish were observed with phenotypic abnormalities, including deformities of the spine, jaw, and cephalic region, that were consistent with vitamin C deficiency during the larval stage. In light of their visible exterior skeletal abnormalities, we suspected that the affected fish would also have abnormal otoliths. Otoliths are dense calcareous structures that function in fish hearing.

Renal failure associated with mucopolysaccharidosis type I in a cat from a MPS I research colony.

Renal failure was diagnosed in an 11-mo-old male domestic shorthair cat from a colony with mucopolysaccharidosis type I lysosomal storage disease. Grossly, the kidneys were enlarged and bulged on cut section. Histology revealed tubular necrosis and regeneration with severe interstitial macrophage accumulation.

Opacification of shape memory polymer foam designed for treatment of intracranial aneurysms.

Shape memory polymer (SMP) foam possesses structural and mechanical characteristics that make them very promising as an alternative treatment for intracranial aneurysms. Our SMP foams have low densities, with porosities as high as 98.8%; favorable for catheter delivery and aneurysm filling, but unfavorable for attenuating X-rays.

Resolution of a proteinuric nephropathy associated with Babesia gibsoni infection in a dog.

A 4 yr old male castrated Labrador retriever was evaluated for a short history of inappetance, lethargy, small-bowel diarrhea, polyuria, and polydipsia. Clinicopathologic abnormalities were consistent with protein-losing nephropathy and renal azotemia. Expansive infectious disease testing implicated Babesia gibsoni via whole blood polymerase chain reaction.

Renal biopsy and pathologic evaluation of glomerular disease.

Presence of suspected primary glomerular disease is the most common and compelling reason to consider renal biopsy. Pathologic findings in samples from animals with nephritic or nephrotic glomerulopathies, as well as from animals with persistent subclinical glomerular proteinuria that is not associated with advanced chronic kidney disease, frequently guide treatment decisions and inform prognosis when suitable specimens are obtained and examined appropriately. Ultrasound-guided needle biopsy techniques generally are satisfactory; however, other methods of locating or approaching the kidney, such as manual palpation (e.

Increased artery wall stress post-stenting leads to greater intimal thickening.

Since the first human procedure in the late 1980s, vascular stent implantation has been accepted as a standard form of treatment of atherosclerosis. Despite their tremendous success, these medical devices are not without their problems, as excessive neointimal hyperplasia can result in the formation of a new blockage (restenosis). Clinical data suggest that stent design is a key factor in the development of restenosis.

Minimal change glomerulopathy in a cat.

A 6-year-old domestic shorthair male castrated cat was evaluated for sudden onset of vomiting and anorexia. A diagnosis of hypereosinophilic syndrome (HES) was made, and the cat was treated with imatinib mesylate. The cat had an initial clinical improvement with the normalization of the peripheral eosinophil count.

Delivery of negatively charged liposomes into the atheromas of Watanabe heritable hyperlipidemic rabbits.

Liposomes have been used as imaging and therapeutic agents in various tissues but only infrequently in the cardiovascular system. We prepared a liposome to target atheromas in a Watanabe heritable hyperlipidemic (WHHL) rabbit model. Liposomes labeled with rhodamine and nanogold were injected intra-arterially into the descending thoracic aortas of WHHL rabbits.

Arrhythmias and elevated troponin I in a dog with steroid-responsive meningitis-arteritis.

A 10-month-old dog was presented with clinical signs of fever, lethargy, inappetence, and cardiac arrhythmias. Computed tomography scan and cerebrospinal fluid analysis supported the diagnosis of steroid-responsive meningitis-arteritis. Echocardiography, electrocardiogram, and elevated serum troponin I supported a diagnosis of myocarditis.