Variation in Pacing Impedance: Impact of Implant Site and Measurement Method

Anderson, Sara E.; Skadsberg, Nicholas D.; Laske, Timothy G.; Benditt, David G.; Iaizzo, Paul A.

doi:10.1111/j.1540-8159.2007.00816.x

Cited by 13 publications

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“…However, it provides an experimental setup that allows fully controllable heartdevice interaction studies and at the same time provides meaningful interaction and visualization of devices and intracardiac structures (6). This approach offers a realistic heart-device interface and allows the investigation of the interaction between the heart and a new device under defined boundary conditions (7)(8)(9)(10). Additionally, the use of crystalloid fluids as perfusate allows visualization of this interaction using endoscopes in a manner that would be impossible in a living animal (11).…”

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confidence: 99%

Interaction of a Transapical Miniaturized Ventricular Assist Device With the Left Ventricle: Hemodynamic Evaluation and Visualization in an Isolated Heart Setup

et al. 2016

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New left ventricular assist devices (LVADs) offer both important advantages and potential hazards. VAD development requires better and expeditious ways to identify these advantages and hazards. We validated in an isolated working heart the hemodynamic performance of an intraventricular LVAD and investigated how its outflow cannula interacted with the aortic valve. Hearts from six pigs were explanted and connected to an isolated working heart setup. A miniaturized LVAD was implanted within the left ventricle (tMVAD, HeartWare Inc., Miami Lakes, FL, USA). In four experiments blood was used to investigate hemodynamics under various loading conditions. In two experiments crystalloid perfusate was used, allowing visualization of the outflow cannula within the aortic valve. In all hearts the transapical miniaturized ventricular assist device (tMVAD) implantation was successful. In the blood experiments hemodynamics similar to those observed clinically were achieved. Pump speeds ranged from 9 to 22 krpm with a maximum of 7.6 L/min against a pressure difference between ventricle and aorta of ∼50 mm Hg. With crystalloid perfusate, central positioning of the outflow cannula in the aortic root was observed during full and partial support. With decreasing aortic pressures the cannula tended to drift toward the aortic root wall. The tMVAD could unload the ventricle similarly to LVADs under conventional cannulation. Aortic pressure influenced central positioning of the outflow cannula in the aortic root. The isolated heart is a simple, accessible evaluation platform unaffected by complex reactions within a whole, living animal. This platform allowed detection and visualization of potential hazards.

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Interaction of a Transapical Miniaturized Ventricular Assist Device With the Left Ventricle: Hemodynamic Evaluation and Visualization in an Isolated Heart Setup

et al. 2016

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“…In a similar embodiment (i.e., without the lungs), this reanimated heart model has been utilized in numerous cardiac studies. In the electrophysiologic area, these studies have included the use of endocardial noncontact mapping, pacemakers, defibrillators, leads, and catheters [ 17 ]. The Visible Heart® model has also been employed to study the dynamic nature of valves and transcatheter valve deployment [ 18 ].…”

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The novel in vitro reanimation of isolated human and large mammalian heart-lung blocs

et al. 2016

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BackgroundIn vitro isolated heart preparations are valuable tools for the study of cardiac anatomy and physiology, as well as for preclinical device testing. Such preparations afford investigators a high level of hemodynamic control, independent of host or systemic interactions. Here we hypothesize that recovered human and swine heart-lung blocs can be reanimated using a clear perfusate and elicit viable cardiodynamic and pulmonic function. Further, this approach will facilitate multimodal imaging, which is particularly valuable for the study of both functional anatomy and device-tissue interactions. Five human and 18 swine heart-lung preparations were procured using techniques analogous to those for cardiac transplant. Specimens were then rewarmed and reperfused using modifications of a closed circuit, isolated, beating and ventilated heart-lung preparation. Positive pressure mechanical ventilation was also employed, and epicardial defibrillation was applied to elicit native cardiac sinus rhythm. Videoscopy, fluoroscopy, ultrasound, and infrared imaging were performed for anatomical and experimental study.ResultsSystolic and diastolic left ventricular pressures observed for human and swine specimens were 68/2 ± 11/7 and 74/3 ± 17/5 mmHg, respectively, with associated native heart rates of 80 ± 7 and 96 ± 16 beats per minute. High-resolution imaging within functioning human pulmonary vasculature was obtained among other anatomies of interest. Note that one human specimen elicited poor cardiac performance post defibrillation.ConclusionsWe report the first dynamic videoscopic images of the pulmonary vasculature during viable cardiopulmonary function in isolated reanimated heart-lung blocs. This experimental approach provides unique in vitro opportunities for the study of novel medical therapeutics applied to large mammalian, including human, heart-lung specimens.Electronic supplementary materialThe online version of this article (doi:10.1186/s12899-016-0023-2) contains supplementary material, which is available to authorized users.

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Isolated Heart Models

Skadsberg

Hill²,

Iaizzo³

2010

Cardiac Electrophysiology Methods and Models

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Variation in Pacing Impedance: Impact of Implant Site and Measurement Method

Abstract: Variations in measured impedances were associated with the nature of implant fixation at all sites in both swine and human hearts.

Cited by 13 publications

References 14 publications

Interaction of a Transapical Miniaturized Ventricular Assist Device With the Left Ventricle: Hemodynamic Evaluation and Visualization in an Isolated Heart Setup

Interaction of a Transapical Miniaturized Ventricular Assist Device With the Left Ventricle: Hemodynamic Evaluation and Visualization in an Isolated Heart Setup

The novel in vitro reanimation of isolated human and large mammalian heart-lung blocs

Isolated Heart Models

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