Developing and optimizing a chronic cyanotic swine model.

BACKGROUND

Pulmonary artery (PA)-left atrial (LA) shunt models in piglets have been described, but technical details critical to limit morbidity/mortality and promote study of chronic cyanosis are lacking. Accordingly, we describe our experience with an optimized technique.

MATERIALS AND

METHODS

In 25 6- to 8-wk-old Yorkshire piglets, a beveled, 8 mm, polytetrafluoroethylene tube graft was anastomosed to the PA and LA. Systemic pressure was maintained at >60 mmHg. Saturation targets were met by adjusting a Teflon band on the graft and distal PA. The target oxygen saturation (SO(2)) was 85% on a 50% fraction of inspired oxygen (FiO(2)). If the SO(2) was <75% on a 50% FiO(2), the graft was constricted to achieve a SO(2) ≥ 90% on a 100% FiO(2) and 75%-80% on a 21% FiO(2). Complications affecting mortality were neutralized with a stepwise strategy to minimize risk.

RESULTS

Thrombosis, blood loss, and arrhythmia were determinants of survival. Protocol optimization over time increased survival while assuring chronic cyanosis. Survival approached 90%, with a SO(2) of 80% to 90%, 3 to 5 wk postoperatively. Complications included bleeding, excessive hypoxemia, uncontrolled shunt flow, arrhythmias, and thrombosis.

CONCLUSIONS

Refinement of surgical technique, shunt adjustment via graft banding, and thrombotic and arrhythmia prophylaxis are the keys to success with this model.