Biomedical subjects

Michael Kopcak

Publications and source records attributed to Michael Kopcak.

3 recordsLinked to original sources

PubMed2005

Myocardial compliance was not altered after acute induction of atrial fibrillation in sheep.

BACKGROUND: Although left ventricular (LV) contractility in atrial fibrillation (Af) is known to change in a beat-to-beat fashion, little is known about the changes in LV compliance in Af. MATERIAL/METHODS: We experimentally induced tachycardic Af (average heart rate - 154 beats per minute) in 18 sheep. LV volume and pressure were simultaneously monitored using a conductance catheter. LV end-diastolic volume (V(ED)) and pressure (P(ED)) were plotted in a beat-to-beat fashion and fitted to the following exponential equation (P(ED)=gamma x e(b x V(ED))) in each animal. A random effects model was constructed to determine if the intercepts and slopes differ. RESULTS: In all animals, those plots after the induction of Af fit quite well to the exponential function (r=0.834+/-0.184) by gating short preceding interval (RR1) beats. By simply taking the natural logarithm of both sides in the equation, the linear relationship (ln(P(ED)) =alpha+ betaxV(ED), where a = lng) was observed in all animals before (normal sinus rhythm, NSR) and after the induction of Af. Only two of 18 intercepts and four of 18 slopes deviate between NSR and Af. Most interestingly, the random effects model clearly detailed that the average animal had intercepts and slopes that were not discernibly different between NSR and Af. CONCLUSIONS: Unlike LV contractility, myocardial compliance did not change after the acute induction of Af. These interesting results may give us insights into the understanding of the physiology in acute rapid Af.

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PubMedDate not supplied

Performance and reliability of the CPB/ECMO Initiative Forward Lines Casualty Management System.

The Cleveland Clinic Foundation CPB/ECMO Initiative Forward Casualty Management System is an economical, compact, transportable, disposable system designed to permit a rapid expansion of trauma management services requiring cardiopulmonary bypass (CPB) or extracorporeal membrane oxygenation (ECMO) pulmonary support. The system, composed of a rotary blood pump, a pump motor driver, and an electronic control console as the blood pumping subsystem, also includes commonly used compatible commercial oxygenators, venous reservoirs, and cannulae. In vitro durability testing accumulated over 100 hours without failure. In vivo reliability was tested in 10 calves under general anesthesia during 6 hours of CPB and ECMO under full heparinization at nominal operating conditions of 4-5 l/min and 2-4 l/min blood flow respectively, and mean arterial pressures between 65 and 100 mm Hg. A mean time to failure of 57 hours was reached during the animal series. Results of these test series demonstrated that this system has the capability to reliably operate during a 6-hour conventional CPB or ECMO procedure, while providing flexibility and ease of use for the operator.

Animals↗

PubMedDate not supplied

MagScrew TAH: an update.

The MagScrew Total Artificial Heart (TAH) system is the result of a close collaboration among the Cleveland Clinic Foundation, Foster Miller Technologies, Wilson Greatbatch Ltd, and Whalen Biomedical Inc. The system components are the thoracic blood pumping unit with attached compliance chamber and refill port, implantable electronic control unit, implantable battery pack, transcutaneous energy transmission system, external battery pack, and a telemetry system for communication with the electronic control unit. System in vitro tests are underway for system characterization and durability demonstration, whereas in vivo tests were conducted to evaluate system performance and biocompatibility under physiologic conditions. The passively filling pump uses a left master alternate left and right ejection control mode and has a Starling law-like response to venous pressure. The in vitro tests documented excellent hydraulic pump performance with high device output of over 9 l/min at left atrial pressures below 12 mm Hg. Atrial balance was well maintained under all test conditions. The in vivo tests demonstrated good biocompatibility without use of anticoagulant therapy. Experimental durations have ranged between 0 and 92 days. Postexplant evaluation of tissue samples did not reveal any sign of thromboembolic events or tissue damage due to device operation.

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