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| Both posterior papillary muscle and Purkinje network contribute the maintenance of ventricular fibrillation in open chest dogs and swine: Effects of catheter ablation and ventricular maze operation |
| 고려의대¹, 포천의대², Utah Valley Medical Center³, Cedars-Sinai Medical Center⁴ |
| 박희남¹, 김진석¹, 임홍의¹, 김광일², 방영호¹, 여윤신¹, 신승용¹, Chun Hwang³, Peng-Sheng Chen⁴, 김영훈 ¹ |
BACKGROUND: We previously reported that radiofrequency catheter ablation (RFCA) targeting the left ventricular posteroseptum (LVPS) and posterior papillary muscle (PPM) terminates or prevents ventricular fibrillation (VF) in rabbit and dog hearts. PPM is the major anchoring structure of VF reentrant wavelets and the harboring site of prominent Purkinje potentials. However, whether the mechanism of VF maintenance is reentry or focal Purkinje firing is unclear.
METHODS and RESULTS: We tested the effects of RFCA and LVPS maze operation (cut and saw) on VF inducibility in 11 dogs and 11 swine. RFCA was performed on the endocardium around PPM with the extension of ablation line to mitral annulus and the apex in 7 dogs and 7 swine (PPM+LVPS) and anterolateral endocardium in 4 dogs (LVAL) with same titrated RF energy (50W, 60°C). LVPS maze operations underwent in 4 swine from mitral annulus to the apex. VF inducibility (100ms, 5 ms, 10 mA for 3 sec) was tested before (3 times) and after (10 times) interventions. PPM was targeted by non-contact endocardial mapping and echocardiography. Results: 1. PPM+LVPS ablation reduced VF inducibility from 100±0% at baseline to 21.9±31.2% (p<0.001), whereas LVAL ablation did not reduce the VF induciblity (100±0% vs. 95.0±5.8%, p=NS) in dogs. 2. In dogs with successful PPM+LVPS ablation, endocardial mapping demonstrated conduction delay along the ablation line. 3. The RF application near PPM frequently initiated VF storm in swine, preventing subsequent testing of VF inducibility (100±0% vs. 100±0%, p=NS). However, LVPS maze reduced the VF inducibility (100±0% vs. 38.5±7.8%, p<0.0001). 4. In contrast to the canine Purkinje network, which was localized on sub-endocardium, swine Purkinje network extended to sub-epicardial layer with higher density (2.74% area vs. 0.02% area, p<0.001) shown by Cx40 immunostain. LVPS maze produced full thickness dissection while RFCA resulted in non-transmural lesions (29.1±9.5% of LV wall thickness).
CONCLUSION: Both PPM+LVPS ablation (Purkinje destruction) and LVPS maze (blocking reentry) reduces the VF inducibility, suggesting both focal firing from Purkinje network and reentry around PPM contribute the maintenance of VF in large animals.
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