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Biomedical subjects

Michael Talcott

Publications and source records attributed to Michael Talcott.

7 recordsLinked to original sources
PubMed2006

Remote controlled magnetically guided pulmonary vein isolation in canines.

BACKGROUND: Ablation of atrial fibrillation (AF) remains a challenging procedure fraught with significant risks and technical difficulties. A magnetically guided catheter system has been developed that potentially addresses many of these challenges. Fully remote controlled electrical isolation of pulmonary veins was performed in canines, facilitated by a three-dimensional computed tomogram (CT) that depicted the anatomic relationships of the pulmonary veins and the left atrium. OBJECTIVE: The purpose of this study was to evaluate the feasibility of pulmonary vein isolation with a novel remote controlled magnetically guided catheter. METHODS: CT scans were obtained in seven healthy male canines. A 7-Fr irrigated magnetic catheter was advanced transseptally to the left atrium. A magnetic guidance system was used to control the orientation of the catheter tip. A mechanical device advanced or retracted the catheter as needed. Pulmonary venography was performed and compared with the CT scan. The CT scan was used as a visual reference to set the magnetic field vectors. Radiofrequency energy was delivered through the irrigated magnetic catheter to isolate the superior pulmonary veins, as judged by elimination of pulmonary vein potentials. RESULTS: The isolation procedure was successful in all 14 pulmonary veins, and there was no evidence of stenosis at 80-100 days postprocedure. CONCLUSIONS: These results demonstrate that remote controlled catheter ablation is safe and effective for segmental pulmonary vein isolation. This technology could facilitate curative ablation of AF in humans and reduce the occupational hazards to the operator of prolonged procedures and radiation exposure.

Animals↗
PubMed2005

Development of exophytic tumor model for laparoscopic partial nephrectomy: technique and initial experience.

OBJECTIVES: To develop and test a porcine model to help teach the techniques needed to perform laparoscopic partial nephrectomy (LPN), which is a technically challenging procedure with necessary reconstructive skills that are difficult to transfer. METHODS: A tumor model was created by unilateral subcapsular percutaneous injection of liquid plastic (Smooth-Cast 320) in five pig kidneys. Five Washington University urologists performed LPN and assessed the efficacy of the tumor model. Subsequently, the tumor model was evaluated as a tool for teaching LPN during the Washington University Advanced Laparoscopic and Robotic Urologic Oncology Course. Twenty-eight participants performed unilateral porcine LPN with the tumor model. Questionnaires were used to assess the utility of this tumor model. RESULTS: Unilateral tumors were successfully created in five pigs and remained intact during all LPN procedures. Visually, the tumors appeared as white exophytic masses. Ultrasonography revealed a well-circumscribed, hypoechoic lesion and a mean diameter of 2.02 cm. The mean operative time was 32.4 minutes. In subsequent testing, 24 (86%) of the 28 participants returned the questionnaire, and 96% responded that the tumor model had enhanced their LPN learning experience. Seven course participants (29%) reported problems with hemostasis, ultrasonography, or laparoscopic instrumentation. Two tumor model-related complications occurred. During the initial evaluation, one pig experienced a fatal pulmonary embolism of the plastic. During the course, a second animal experienced extravasation of the solution into the renal collecting system. CONCLUSIONS: For surgical education purposes, the Smooth-Cast model is an effective surgical tool for LPN. Most of the surgeons in this evaluation believed the model enhanced their learning experience.

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PubMed2004

Maintaining the surgical research facility: the role of the surgical technician.

Building a well-equipped surgical facility is only half the battle. By ensuring that these facilities and their equipment are kept clean and well maintained, and that clear and thorough documentation is kept, research staff can protect both the quality of their work and the well-being of their animal patients.

Disinfection↗
PubMed2003

Magnetic guidance system for cardiac electrophysiology: a prospective trial of safety and efficacy in humans.

OBJECTIVES: We evaluated in humans the safety and efficacy of a novel magnetic guidance system (MGS) for electrophysiological mapping, pacing, and ablation. BACKGROUND: Catheter ablation of atrial fibrillation and other complex arrhythmias requires precise catheter manipulation and stabilization. We have shown in animals that the MGS can precisely manipulate a mapping catheter within the heart with an external magnetic field rather than manual catheter control. METHODS: Thirty-one adults referred for diagnostic electrophysiology studies were enrolled in a prospective trial of the MGS. The magnetic catheter was navigated to preselected sites in the right atrium (RA) and right ventricle (RV) in the first 20 patients. Electrograms were recorded at each target site, and pacing thresholds were measured. In a subset of five patients, RA and RV electrograms and stimulation thresholds were recorded with both a standard ablation catheter and the magnetic catheter. Eleven additional patients were recruited for supraventricular tachycardia (SVT) mapping, and seven of these underwent ablation. RESULTS: Navigation was successful in 200 of 202 predetermined right-sided navigation targets and 13 of 13 targets in the left atria. Pacing thresholds and electrogram amplitudes in the RA and RV were not significantly different between the standard and magnetic catheters. The SVT mapping with the magnetic catheter was successful in 13 patients, including 4 with left-sided accessory pathways. The MGS was used for successful ablation of SVT in seven of seven patients. There were no procedural complications. CONCLUSIONS: These results demonstrate that the MGS can be used for intracardiac mapping, pacing, and ablation safely and effectively.

Adult↗
PubMed2002

Novel, magnetically guided catheter for endocardial mapping and radiofrequency catheter ablation.

BACKGROUND: Ablation of complex arrhythmias would be greatly facilitated by more precise control of ablation catheters. A feasibility study was performed in animals to evaluate a novel magnetic guidance system (MGS) that generates a magnetic field to control the movement and position of a magnetic ablation catheter. METHODS AND RESULTS: The MGS is composed of a digital biplanar fluoroscope within an array of superconducting electromagnets that surround the torso of the experimental animal and a computer control system that generates a composite magnetic field for directional catheter deflection. Magnetic catheter navigation was performed in dogs and pigs (20 to 30 kg). A 7F magnetic ablation catheter was used for intracardiac navigation and radiofrequency ablation. The performance of a standard 7F deflectable catheter was not affected by the MGS. The magnetic catheter was navigated successfully to 51 predefined targets throughout the heart in 6 animals. In 5 animals, the magnetic catheter, guided by a 3D computed tomogram, was successfully navigated to all pulmonary veins. Navigation accuracy was estimated as <1 mm displacement from the target. The magnetic catheter was used to ablate the atrioventricular node in 4 animals and to perform linear ablations across the endocardial surface underlying an epicardial multielectrode recording plaque in 4 animals. CONCLUSIONS: These results demonstrate that the MGS can navigate and stabilize an ablation catheter at endocardial targets. Linear or focal radiofrequency ablation with the magnetic catheter is not compromised by the magnetic field. This technology provides precise control of endocardial catheters.

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PubMedDate not supplied

Transplantation of pig metanephroi.

To determine whether pig metanephroi grow and differentiate after allotransplantation or xenotransplantation across a highly disparate barrier, we implanted metanephroi from embryonic day 28 (E28) pig embryos into the omentum of unilaterally nephrectomized adult pigs or C57Bl/6J mice (hosts). Some mouse hosts received anti-CD45RB, anti-CD154, and anti-CD11a (costimulatory blockade). E28 pig metanephroi were < 0.2 mm in diameter and contained only metanephric blastema and segments of ureteric bud. Pig metanephroi transplanted into pigs underwent growth and differentiation of nephrons over a 2 week period without the need for costimulatory blockade of hosts. In contrast, pig metanephroi did not grow or differentiate in mice that received no costimulatory blockade. However, by 2 weeks posttransplantation in mice in which costimulation was blocked, metanephroi from E28 pigs had enlarged, become vascularized, and had formed mature tubules and glomeruli. By 3 weeks posttransplantation in mice, metanephroi had grown to the point that they were approximately half the volume of the native mouse kidney. Here we show that growth and development of pig metanephroi occurs posttransplantation across an allogeneic or highly disparate xenogeneic barrier.

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