Aortic valve replacement in sheep with a novel trileaflet mechanical heart valve prosthesis without anticoagulation

Abstract

Background: Even after decades of intensive research, an ideal heart valve prosthesis remains elusive. Shortcomings of conventional devices include reduced durability of bioprostheses and the thrombogenicity of mechanical substitutes, necessitating anticoagulation and resulting in imperfect hemodynamics. Here we present in vivo results of a novel mechanical heart valve prosthesis aiming for freedom from anticoagulation.Methods: Four female sheep had their aortic valves replaced using the novel mechanical heart valve (size 21 mm), with no postoperative anticoagulation treatment. This trileaflet heart valve was designed with the pivots in the systolic central flow. Hemodynamics, biochemistry, hematology, and macroscopy and microscopy were studied at 90 days in 2 sheep and at 1 year in the other 2 sheep.Results: Mean (<6 mm Hg) and peak (<10 mm Hg) aortic transvalvular gradients remained low during the study period. Aortic regurgitation was trivial, and central traces were only rarely observed. The rate of thrombotic events was very low, with none macroscopically and microscopically visible thrombotic material on the device. Biochemistry and hemotology were unchanged without hemolysis. In 3 sheep, the fibrous pannus and mitral leaflet were partially folded over the edge of the annular body. Apart from organic/inorganic deposits on the leaflets after 1 year, the ultrastructurally evaluated leaflets were similar to those of nonimplanted controls. Conclusions:The preliminary in vivo results of this novel anticoagulation-free aortic mechanical heart valve are promising with excellent hemodynamics and a very low risk of thrombotic events. (JTCVS Open 2021;7:76-88) Novel trileaflet mechanical heart valve explanted after 375 days in a sheep model.

Reflections on valve-sparing operations utilizing straight tube versus Valsalva grafts

“…The importance of the straight cylindrical position of the commissures was recently reported by Paulsen et al ( 6 ), which highlighted that it results in preserved leaflet coaptation, decreased regurgitation and lower forces on the leaflets, potentially improving durability in contrast to Valsalva grafts (Vascutek Terumo, Vascutek Deutschland GmbH, Hamburg, Germany) with radially displaced commissures ( 6 ). These results once again confirm the paradigm that nature provides the best solution for any task, a concept that in my experience was also beneficial for other procedures: the bicaval heart transplantation ( 7 ), the direct anatomical anastomoses of the great arteries during correction of the transposition of the great arteries ( 8 ), the subcoronary Ross operation and even a novel anticoagulation-free mechanical heart valve with three wing-shaped leaflets ( 9 ). But not only an anatomically correct prosthesis, but also adequate surgery is decisive for success, and the David procedure is challenging.…”

Comparative analyses of blood flow through mechanical trileaflet and bileaflet aortic valves

“…An alternative, although more expensive, might be ex vivo modelling [31]. Such a methodology was applied in the study of a novel trilea et valve [15,32]. The authors mounted the valve in a pulse duplicator that simulated the physiological system and studied, among others, clot formation.…”

“…They concluded that the TRI valve better conserved the helical ow than the BIL valve. Schaller et al [15] implanted four novel mechanical prostheses of the aortic valve in sheep. The mechanical valves consisted of three lea ets made of poly-ether-ether-ketone.…”

Trileaflet Mechanical Valves: What Is Already Known? A Systematic Review

“…The results of the first in-vivo testing of the SV were published in 2021 [50]. Four female sheep were implanted with the SV.…”