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Prosthetic Aortic Valve Fixation Study: 48 Replacement Valves Analyzed Using Digital Pressure Mapping
Candice Y. Lee1, Ronald E. Ross1, David C. Liu2, Kamal R. Khabbaz2, Angelo J. Martellaro3, Heather R. Gorea3, Jude S. Sauer3, Peter A. Knight1.
1University of Rochester Medical Center, Rochester, NY, USA, 2Beth Israel Deaconess Medical Center, Boston, MA, USA, 3LSI SOLUTIONS, Victor, NY, USA.

OBJECTIVE: While prostheses attachment is critical in open, minimal access and transcatheter aortic valve replacement (AVR) procedures, reliable prosthetic security remains a challenge. Accurate techniques to analyze prosthetic fixation pressures may enable the use of fewer sutures, while reducing the risk of perivalvular leaks (PVL).
METHODS: Customized digital thin film (0.2mm) pressure transducers were sutured between aortic annulus models and 21mm stented bioprosthetic valves with either 15 x 4mm, 12 x 4mm or 9 x 6mm wide pledgeted 2-0 sutures. Simulating open or minimally invasive access, four surgeons, blinded to data acquisition, each secured 12 valves using manual knot tying (hand-tied, HT; knot pusher, KP) or automated mechanical titanium fasteners (TF). Real-time pressure measurements and times were recorded. 2-D and 3-D pressure maps were generated for all valves. Pressures < 80mm Hg were considered at risk for PVL.
RESULTS: Pressures under each knot (Intra-Suture) fell below 80mm Hg in 5/144 HT, 7/144 KP and 0/288 TF; p<0.001 for manual vs. TF. Pressures outside adjacent suture loops (Extra-Suture) were <80mm Hg in 10/60 HT, 0/60 KP and 0/120 TF sites in the 15 x 4mm valves, 17/48 HT, 25/48 KP and 12/96 TF in the 12 x 4mm valves and 15/36 HT, 17/36 KP and 9/72 TF in the 9 x 6mm valves; p<0.001 manual vs. TF. Annular areas with pressures <80mm Hg ranged from 31% of the sewing-ring area (12 x 4mm, KP) to 0% (all open TF). Fig. 1 provides histograms of Intra- and Extra-Suture pressures combined from all surgeons’ HT and TF open 15 x 4mm and 12 x 4mm valve results, along with sample pressure maps from one surgeon. The average time per manual knot, 46sec, (HT: 31; KP: 61sec) was greater than TF, 14sec (p<0.005).
CONCLUSIONS: Reduced operative times and PVL risk would fortify the advantages of surgical AVR. This research encourages continued exploration of the technical factors toward optimizing AVR security.

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