Retrograde lung perfusion in the treatment of massive pulmonary embolism. A randomised porcine study

INTRODUCTION: The treatment of massive pulmonary embolisms with an associated cardiac arrest is controversial; however, surgical thrombectomy with extracorporeal circulation (ECC) is an option for treatment. It is difficult to remove all thromboembolic material. Theoretically, retrograde blood perfusion through the lungs may be beneficial.

OBJECTIVES: To investigate whether retrograde blood perfusion through the lungs during a thrombectomy is beneficial.

METHODS: Twelve pigs were prepared for ECC. Repetitive injections of preformed blood thrombi into the right atrium resulted in cardiac arrests. ECC was established after 10minutes of cardiac arrest, and after a sternotomy, the main pulmonary artery was incised and as much thrombotic material as possible was removed from the pulmonary arteries. The pigs were randomised to ECC for one hour either with or without retrograde perfusion in the pulmonary circulation. After one hour, the released material was removed from the pulmonary arteries, and the incision was sutured. The pigs were weaned from the ECC. After sacrificing the pigs, they were autopsied with special attention to the amount of remaining thrombi. Additional histological analyses were performed with special attention to microembolisms, atelectases, and signs of tissue damage.

RESULTS: All of the pigs were weaned from the ECC. The amount of the embolic material removed varied considerably, as did the amount removed after the retrograde or antegrade perfusion, and there was no significant difference between the two treatment modalities. There were no signs of tissue damage in the lungs.

CONCLUSIONS: Retrograde lung perfusion was not generally beneficial in the treatment of massive pulmonary embolism in this setup; however, it may be an option if only a modest amount of material is accessible in the pulmonary artery.