Animal studies on the mechanisms and radiofrequency catheter ablation of the syncope with vasovaga1 syncope -radiofrequency ablation of cardiac nerve attenuates bezold-jarisch reflex in canine

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Background: The Bezold–Jarisch Reflex (BJR) is one of the main causes for Vasovaga1 Syncope (VVS). Blocking the efferent pathways of the vagus ganglia in the heart may attenuate the BJR. Objective: To observe the influence of radiofrequency catheter ablation of the interventricular sulcus fat and endocardial nerve potential on Bezold-Jarisch Reflex (BJR) induced by veratridine in canine. Methods: Six mongrel dogs were anesthetized and their chest were opened through a right thoracotomy to expose the Interventricular sulcus fat. Veratridine was injected into the left ventricle at bolus doses of 15 ug/kg through a catheter to induce BJR. The Sinus Cycle Length (SCL), Systolic Arterial Pressure (SAR), Diastolic Arterial Pressure (DAP), Mean Arterial Pressure (MAP), Left Ventricle Systolic Pressure (LVSP), Left Ventricle Diastolic Pressure (LVDP) and Mean Left Ventricle Pressure (MLVP) were measured under the baseline and after ablation of fat pad; the changes of the above parameters (ΔSCL, ΔSAP, ΔDAP, ΔMAP, ΔLVSP, ΔLVDP and ΔMLVP) were calculated. Then the same dose of veratridine was injected under mapping along the mitral annulus, and potential nerve ablation and the changes of the above parameters were observed. Results: BJR was successfully induced in the 6 animals; the animals has prolonged Sinus Cycle Length (SCL) and decreased MAP and MLVP. After ablation, the prolongation of SCL after injection of veratridine was markedly reduced [229.2±92.3] ms vs [39.3±14.1] ms, p< 0.01.All the pressures were decreased after injection of veratridine, with significant decrease found only for DAP and MAP both p< 0.05. Conclusion: Ablation of the interventricular sulcus fat and endocardial nerve potential fat can effectively attenuate the decrement of heart rate and the decrement of DAP and MAP during the BJR induced by veratridine, which provides a basis for the treatment of VVS.