Ruminant model for hemodialysis cannulation.

BACKGROUND: Preventative strategies that minimize hemodialysis access complications remain limited. OBJECTIVE: This study aimed to address this gap by developing a Caprine cannulation model to investigate the impact of repeated cannulations on vascular access patency rates. RESEARCH DESIGN AND MEASURES: In this pilot study, a meta-analysis was conducted using experimental control data from four trials to explore the impact of Caprine breed (independent variable) on the dependent variables that affect hemodialysis cannulation, including AVF growth, AVF depth, and flow rate. SUBJECTS: Arteriovenous Fistulas (AVFs) were created using the carotid artery and jugular vein in the necks of seven goats from the French alpine, dwarf, and pygmy breeds. All seven AVFs exhibited vessel remodeling patterns similar to that observed in humans and remained patent, enabling hemodialysis access over the 6 month study. RESULTS: Over the course of 18 weeks, a total of 291 cannulations were completed using standard 15 g dialysis needles without complications demonstrating the feasibility of using the Caprine species as a cannulation model. The ease of access coupled with the animals' cooperative behavior further contributes to the suitability of the Caprine species for hemodialysis investigations. Notably, no infections or clinically significant incidents were observed throughout the study. CONCLUSIONS: The stability of AVF patency and flow underscores the viability and potential of the Caprine species animal model as a valuable research platform for exploring interventions aimed at improving vascular access survival in hemodialysis patients.

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. This laboratory's experience in numerous collaborative projects involving veterinary pathologists, biomedical engineers, physicians, and other scientists has led to a set of interrelated assessments to determine pathologic end points as a means to address these challenges and achieve study outcomes. Thorough device evaluation is often accomplished by utilizing traditional paraffin histology, plastic embedding and microground sections, and advanced imaging modalities. Combining these advanced techniques provides an integrative, comprehensive approach to medical device pathology and enhances medical device safety and efficacy assessment.

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. The material characteristics of the device were analyzed to show tunability of the glass transition temperature (Tg) and the expansion rate of the polymer to ensure adequate time to deliver the device through a catheter prior to excessive foam expansion. Mechanical analysis and flow migration studies were performed to ensure minimal risk of vessel perforation and undesired thromboembolism upon device deployment. The efficacy of the device was verified by performing blood flow studies that established affinity for thrombus formation and blood penetration throughout the foam and by delivery of the device in an ultrasound phantom that demonstrated flow stagnation and diversion of flow to collateral pathways.