Direct Visualization of a Transcatheter Pulmonary Valve Implantation Within the Visible Heart
A Glimpse Into the Future
The complexity of intracardiac interventions has increased with the advent of transcatheter valve replacement, and advanced imaging modalities will be required both to plan and to guide these interventions. The imaging modalities currently used have limited temporal and spatial resolution. We set out to take a glimpse into the future by demonstrating the exquisite picture quality of direct visualization of a Melody*† (Medtronic) transcatheter pulmonary valve implantation1–3 within the Visible Heart† (Medtronic).4 With the advent of major advances in visualization techniques (eg, trans-blood, enhanced 4-D), this imaging quality could become a clinical reality.
Endoscopic cameras were placed within the right ventricle of a human donor heart that was deemed not viable for transplantation. The heart was reanimated and perfused with a clear Krebs-Henseleit buffer according to previously described Visible Heart methodologies.4 Furthermore, this heart had an intrinsic rhythm and could sustain function in a 4-chamber working mode.4 Baseline systolic and diastolic right ventricular pressures were 35/4 mm Hg, and all steps of the transcatheter pulmonary valve implantation procedure could be monitored with direct visualization.
Initially, a guidewire was positioned in the right ventricular outflow tract and across the native pulmonary valve (Data Supplement Movie I). Next, the delivery system was placed over the guidewire and advanced until the valve was properly positioned at the native pulmonary valve. Once in position, the transcatheter pulmonary valve was unsheathed. The overlay sheath protected the leaflets and chordae of the tricuspid valve from any damage that could have been caused by the collapsed stent of the transcatheter valve. The first balloon of the double-balloon delivery system was then inflated, partially deploying the valve. Finally, the second balloon of the delivery system was inflated, and the deployed transcatheter pulmonary valve could be observed (Data Supplement Movie I). Shown in Data Supplement Movie II is the implanted, functioning transcatheter pulmonary valve as viewed from the right ventricular outflow tract and from the pulmonary trunk, providing qualitative assessment of performance.
The Visible Heart methodology provides imaging that should be considered the gold standard for clinical imaging modalities. At present, it offers new opportunities for in vitro and bench testing of new devices.
Sources of Funding
This work was funded in part by the Institute for Engineering in Medicine at the University of Minnesota and by Medtronic, Inc.
Drs Laske and Hill are employed by and have ownership interest in Medtronic, Inc, the maker and registered trademark holder of Melody and Visible Heart. Drs Bonhoeffer and Iaizzo have consulted for Medtronic, and Dr Bonhoeffer has received honoraria from Medtronic. J. Quill and Dr Iaizzo have received other research support.
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