Timothy G. Laske1, John R. Liddicoat1, Paul A. Iaizzo2.
1Medtronic, Minneapolis, MN, USA, 2University of Minnesota, Minneapolis, MN, USA.
OBJECTIVE: The development of devices and procedures for minimally invasive approaches to structural remodeling of the heart requires a thorough understanding of both cardiac anatomy and the potential complications that can occur. This study aimed to assess the utility of combining intracardiac imaging within the Visible Heart® in combination with clinically available imaging modes.
METHODS: Normal porcine hearts and normal and diseased human hearts were reanimated using a crystalloid perfusate that allowed intracardiac imaging. Beating heart access to the heart chambers was performed via the right and left ventricular apices and atria. Both native anatomies, and hearts with annuloplasty rings/bands and bioprosthetic heart valves were studied. Simultaneous imaging was performed with multiple imaging modes, including videoendoscopy, echocardiography (ICE, TEE, TTE), and fluoroscopy. Cardiac performance was monitored throughout the procedures using intracardiac pressure catheters, flow meters, and electrocardiograms.
RESULTS: The Visible Heart® was successfully employed in the testing and development of several minimally invasive tools, techniques, and devices. Both human and porcine hearts were evaluated. The procedures and devices studied included those for: PFO and septal defect closure, transeptal punctures, surgical ablation, atrial appendage isolation, mitral valve repair, and transcatheter replacement of the aortic and pulmonic valves. The intracardiac imaging allowed for the identification and eventual avoidance of complications, including chordal rupture, damage to valve leaflets, and cardiac perforation.
CONCLUSIONS: The in vitro isolated heart model, the Visible Heart®, allows for novel examination of device-tissue interactions within a beating heart in order to evaluate minimally invasive device placement and performance. This model provides product designers and clinicians with a rapid method to critically assess prototypes and procedures, thus expediting design and clinical decisions. The future of minimally invasive cardiac surgery will include numerous beating heart procedures and is likely to involve multiple, simultaneous imaging modalities. Combining these imaging modes will allow for verification of proper device positioning, refinement of device/deployment procedures, and the evaluation of resultant cardiac function. 
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