Self-expandable valved stent of large size: off-bypass implantation in pulmonary position

Zhou, Jun Qing ; Corno, Antonio F. ; Huber, Christophe H. ; Tozzi, Piergiorgio ; von Segesser, Ludwig K.

In: European Journal of Cardio-Thoracic Surgery, 2003, vol. 24, no. 2, p. 212-216

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    Summary
    Objective: To evaluate the feasibility of the off-bypass implantation of a self-expandable valved stent of large size in pulmonary position. Materials and methods: A glutaraldehyde preserved valved bovine jugular xenograft with internal diameter=22 mm, mounted in two rings of nitinol ‘Z' stent, expandable from 7 to 24 mm of internal diameter, was acutely evaluated in 6 adult pigs, mean body weight 55.6 kg (range 47-67 kg). Through a stent-graft delivery system (24 French) the self expandable valved stent was implanted off-bypass in pulmonary valve position by trans-ventricular approach through median sternotomy. Results: The mean diameter of the main pulmonary artery measured was 21.7±1.6 mm. The mean length of the self expandable valved stent was 23.1±0.7 mm, the mean internal diameter 21.6±0.7 mm and the mean external diameter 26.3±0.7 mm. The mean peak pressure gradient recorded across the valve was 6.33±2.8 mmHg (range 4.5-9.6 mmHg) at Doppler echocardiography, and 4.5±3.1 mmHg (range 0-7 mmHg) at invasive measurement, with a pulmonary blood flow of 3.03±0.05 l/min. Intra-vascular ultrasound showed complete opening and closure of the valve (mean area reduction from 315.08±54.13 to 0 mm2). Conclusions: (a) Off-bypass implantation of self-expandable valved stent is feasible in pulmonary position; (b) off-bypass surgical approach allows for valved stent implantation of adult size with adequate hemodynamic functioning; and (c) intra-vascular ultrasound makes implantation and evaluation easy and reproducible