The Experimental Study Of Native Percutaneous Catheter Thrombectomy Device For Acute Massive Pulmonary Embolism

Part 1: The establishment of the experimental animal model of acute massive pulmonary embolismPurpose: To find a way to make the model of acute massive pulmonary embolism for ours studies.Materials and Methods: One dog randomly selected as pre-research group in six dogs and other five dogs belonging to the research group. After anesthetized, the 5F catheter sheath was inserted into the femur artery and suctioned 100ml blood using 20ml syringes and blood was mixed with 1.2ml EACA in every springe. Mixture was clotted under room temperature after 30mins then immersed the clots in 70℃water for 10mins and kept them in refrigeratory. A 10F guilding catheter is inserted into the central branch of pulmonary artery through the femur vein. Thrombi were injected through the catheter under monitoring pressure of pulmonary artery until the central branch of lateral pulmonary artery was occluded. Blood gas was tested before embolization and after embolization , continuously monitored pulmonary artery pressure and discontinuously performed angiogram. The mean time from embolization to euthanasia was 12 hours, the lung specimens were resected for histological examination.Results: After embolization, animals presentation was shortness of breath and decreased of aortic pressure. One animal died of cardiogenic shock after thrombus injection; The shortness of breath recovered to normal after 30-50mins; One animal presented with tachycardia and premature ventricular beat; One was partly recanalization ; The other successfully occluded in central branch of pulmonary artery; the pulmonary pressure can reached above 50mmHg after occluded and then slowly down , after 6 hours the pressure can kept above 30mmHg; SO₂,PO₂and HbO₂decreased after embolism and part can recovered normal till 12 hours later; Pathologic examination showed the formation of red and mix thrombi in the vessel.Conclutions: This method for making acute massive pulmonary embolism animal model was success, and it can be used as animal model for our experiment.Part 2: Percutaneous catheter thrombectomy device for acute pulmonary embolism in vitro testingPurpose: To determine the efficacy of clot removal of the new percutaneous cather thrombectomy devices and to compare with catheter aspiration in vitro.Materials and methods: The clots were made in the same way as study part one; Experiment was done in a lucent plastic tube with a 90% stenosis immersed in a pans which was full of water. The test was divided into two parts, thrombectomy device was compared with the catheter aspiration, each part was going on 10 times, recorded the time and the liquor.Results: The mean time of the thombectomy device part is 24 seconds, the mean collected liquor is 35ml and without occlusion of the tube; The mean time of catheter aspiration is 31 seconds and the mean liquor is 36ml, the total times of the occlusion is 10 .Conclusions: This device can avoid occlution of the catheter during operation ,and reduce the procedure , shorten the operation time. Part 3: Percutaneous catheter thrombectomy device for acute pulmonary embolism in vivo testingPorpose: To evaluate efficacy of thrombus removal ,feasibility and safety of the percutaneous catheter thrombectomy device in animal model.Materials and methods: One dog randomly selected as pre-research group in 7 dogs, the others belonging to research group. After animal model was created as study 1, the catheter sheath was inserted into the occluded pulmonary artery through right femur vein in 3s and left femur vein in 1s and right internal jugular vein in 1s began to remove the thrombi, recorded the thrombectomy time and blood volume, Blood gas was tested before and after embolization and removement of thrombi, continuously monitored pulmonary artery pressure and discontinuously performed angiogram. One was randomly selected to perform CTPA. The mean time from recanalization of the vascular to euthanasia was 2 hours, the lung specimens were resected for histological examination.Result: One was died of cardiogenic shock while the catheter was advancing in the infra vena cava, one died of penetration of the pulmonary artery during removing thrombi, others were alive at end of the test. Mean time of removing thrombi was 2.4 minutes, mean volume of blood was 84ml; angiogram showed that the central pulmonary artery which occluded was reopened but distal branches still remained thrombi , angiogram appearance was consistent with CTPA which also showed effusion around the vascular. The pulmonary pressure, SO₂, PO₂ and HbO₂ recovered to normal level after thrombectomy; Pathologic showed the occluded central branch was re-open , there were thrombi remained in the distal branches and effusion around artery.Conclusions: This device is effective, feasible and comparatively safety in treatment of acute massive pulmonary embolism, and furture study should be done.