Comparision Of The Pathological Effects Of Radiofrequency And Through-the-balloon Ultrasound Catheter Ablation In The Orifice Of The Vena Cava In Canines

Objective To observe and compare the pathological effects and platelet function changes after RFCA and TTB-USA application in the orifice of the vena cava in dogs and explore the pathological mechanism of venous stenosis and evaluate the safety, efficacy of the tow methods.Methods Ten mongrel dogs were divided into two groups. RFCA and TTB-USA were performed within the vena cava respectively after vena cava angiography. Thirty minutes later, vena cava angiography was repeated and then one dog from each group was euthanized. Sections were cut and examined under the light microscope. Four and twelve weeks after the ablation, two dogs from each group were selected and the same procedure was repeated respectively. Further more, blood samples were got before the procedure, soon after the cannula, thirty minutes after the ablation and 48 hours after the ablation respectively and the concentration of a -granule membrane protein(GMP-140) were tested.Results None of the dogs in the TTB-USA group was found with venous stenosis at 30 minutes and 4 weeks after the ablatoin while one dog which was euthanized at the 12th week was found with moderate venous stenosis at the orifice of the inferior vena cava. All the RFCA veins developed venous stenosis soon after the ablation and 12 weeks after the procedure while none was found at the 4th week. On gross examination, RFCA produced tissue necrosis and white, firm, irregularly contracting scars while lesions caused by TTB-USA were smooth, even and continuously circumferential. Histological examination-revealed that intimal injury and proliferation, transmural necrotic myocardium in various stages of collagen replacement and vascular wall contraction were found in both groups while it was more seriousthrombosis. The concentration of GMP-140 elevated soon after the cannula and last at least for 48 hours, but 'the degree of uprising was more slightly in TTB-USA group than that in RFCA group.Conclusions Both RFCA and TTB-USA could produce transmural lesions in the vena cava wall and therefore could be used to cure focal atrial fibrillation. TTB-USA injured venous intimal slightly and the lesions tended to be continuously circumferential, even and smooth, so it is of less possibility to lead to venous stenosis comparing with RFCA. The ablated veins shared similar pathological procedure while it was slighter in the TTB-USA ones. Both vascular puncture and canuula could active blood platelet while RFCA and TTB-USA enhanced the process severely. The activation of blood platelet was corelated with thrombosis and the stenosis of the ablated veins but it was also slighter in the TTB-USA ones.