Surgical palliation of primary pulmonary arterial hypertension by a unidirectional valved Potts anastomosis in an animal model.

OBJECTIVE

Patients with idiopathic pulmonary hypertension are at risk for right-sided heart failure and sudden death. Despite improvement in pharmacologic management, some still require lung transplantation. Potts anastomosis has been demonstrated as a good palliation in children to alleviate symptoms and medical therapy despite desaturation in the lower part of the body. Young adult patients with pulmonary hypertension and isosystemic pressure remain at risk, particularly at exercise. The goal of this research was to find a palliation for patients in whom suprasystemic pulmonary hypertension developed at exercise. Creating a Potts anastomosis involved a unidirectional valve between the left pulmonary artery and the descending aorta.

METHODS

Experimental study was performed on 14 pigs. A prosthetic patch of polytetrafluoroethylene (Gore-Tex; WL Gore & Associates Inc, Newark, Del) was used to create the unidirectional valve and implanted in the Potts anastomosis. Via a left thoracotomy, an aorto-aortic shunt between the aortic isthmus and the distal descending thoracic aorta was instituted, allowing a safe surgical procedure. Intrapulmonary injection of Erciplex glue (Peters Surgical, Bobigny, France), diluted in 70% alcohol, was used to create acute pulmonary hypertension. The right to left shunt across the unidirectional valvular patch was evaluated after clamping the aorta in the acute phase of pulmonary hypertension by echo-pulsed Doppler at the level of the descending thoracic aorta by withdrawal of blood gas (arterial carbon dioxide tension, alveolar carbon dioxide tension) and assessment of peripheral oxygen saturation. Similar reevaluation of the shunt was performed at a mean interval of 13 ± 2.5 weeks.

RESULTS

In the first series, Erciplex glue increased pulmonary artery pressure from 15.3 ± 3.1 mm Hg to 38.7 ± 6.0 mm Hg. Mean peripheral oxygen saturation decreased from 100% to 85% ± 1.5%. Mean partial pressure of carbon dioxide increased from 31.9 ± 9.1 mm Hg to 46.2 ± 12.5 mm Hg after shunt opening (P < .01), and mean peripheral oxygen decreased from 435.1 ± 109.4 mm Hg to 261.9 ± 77.9 mm Hg (P < 0.05), indicating right to left shunt through the Potts valve (P < .013). Pulsed Doppler showed a mean peak laminar flow of 133.3 ± 35.3 cm/s before aortic clamping, turbulent flow of 234.9 ± 40.1 cm/s after glue injection, and return of laminar flow 128.5 ± 30.1 cm/s after aortic isthmus unclamping. In the second series, the same results were obtained but with a lesser peak flow velocity because of the endothelialization on the valvular patch. Gross analysis of the patch did not show thrombosis, aneurysm, or fissure.

CONCLUSIONS

Palliation of exercise suprasystemic pulmonary hypertension was demonstrated by a unidirectional valved Potts anastomosis. This technique can be of help in young adult patients with pulmonary hypertension and isosystemic pressure but with exercise intolerance.