Radiofrequency Ablation Of Canine Cardiac Fat Pad Attenuated Bezold-Jarisch Reflex Induced By Veratridine

After 16 mongrel dogs were anesthetize, a right lateral intercostal thoracotomy was performed and cradled the heart. The ECG, arterial pressure and left ventricle pressure were recorded continuous.Before the ablation of the cardiac fat pad, during atrial pacing to maintain the heart rate and after the ablation fat pad,veratridine was injected into the left ventricle in bolus doses of 10μg/Kg to induce Bezold-Jarisch reflex(BJR).Before induced the BJR, the heart rate and the arterial pressure recovered. Each fat pad and underlying tissue were excised. Serial sections were taken and stained with hematoxylin and eosin for microscopic examination. The result were compared with the dog whose fat pad haven't been ablated because the failure of the operation.7 dogs have been completed the experiment successfully.Injection of veratridine into left ventricle induced the BJR and the hear rate, mean left ventricle pressure (MLVP) and mean arterial pressure (MAP) decreased.Maintaining the heart rate by pacing the right atrium just lightly attenuated the decrease of MLVP and MAP.Ablation of the three fat pad almost abolished the decrement of heart rate during the BJR,but lightly attenuated the decrement of MLVP and MAP. It indicated that denervation of the atrium partly abolish the negative chronotropic, a inotropic and dromotropic effects during the BJR.but the decrement of peripheral resistance and blood vessel dialation couldn't be affected.It can be conclued that the heart rate and the negative inotropic of the atrium have little effects on the blood pressure.