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Tissue-engineered Pediatric Pulmonary Valve Conduit in Growing Lamb Model
Zeeshan Syedain, Mathew Lahti, Richard Bianco, Robert Tranquillo.
University of Minnesota, Minneapolis, MN, USA.

OBJECTIVE: A heart valve that can grow for pediatric patients has not yet been demonstrated. Several thousand children born each year with congenital heart valve defects thus face the grim prospect of repeated open heart surgery until adulthood. Here we present a novel tri-tube engineered valve possessing durable commissures and somatic growth potential, and initial in vivo data in a growing lamb model.
METHODS:We conceived a valve design with durable commissures and growth potential constructed from three biologically-engineered tubes of collagenous matrix and resorbable suture, with each tube creating a “leaflet” (patent pending). This valve was evaluated in an accelerator wear tester and in a pulse duplicator showing adequate hydrodynamic function. In vivo assessment of the valve implanted into the pulmonary artery of a growing lamb with compromised pulmonary valve is ongoing.
RESULTS: The novel tri-tube valve was evaluated for 8M cycles showing intact commissures unlike our previous tube-in-tube valve design (Reimer et al. 2017). Hydrodynamic performance under pulmonary pressure gradients was adequate (Fig. 1a,b). A 12-week old lamb implanted with a tri-tube valve in the pulmonary artery (Fig. 1c) gained weight from 25.6kg to 44.6 kg during the first 20wk of ongoing implantation. During this time, the valve lumen dimeter increased from 18.9mm to 22.7mm with cardiac output increased from 4.1 LPM to 7.1 LPM. The EOA increased from 0.88cm2 to 2.15cm2 (Fig. 1d), indicating functional growth of the valve. Regurgitation was trivial to mild at all time points with only 6mm Hg systolic pressure drop at 20wk.
CONCLUSIONS: We present a novel tri-tube design of a pulmonary valve with strong commissures because force is borne primarily by the tubes, not the suture that attaches the tubes together. The study is ongoing with additional animals and longitudinal monitoring with ultrasound to a target of 52 weeks of growth. Funded by NIH R01-HL107572


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