de Micheli A, Medrano G A, Casanova J M
Departamento de Farmacología, Instituto Nacional de Cardiología Ignacio Chávez, México.
Arch Inst Cardiol Mex. 1995 Sep-Oct;65(5):403-12.
Experimental ventricular tachycardias were provoked in dog hearts with minute crystals of aconitine introduced into the periphery of an infarcted area, produced by intramural injection of 1-1.5 ml of phenol near the apex of left ventricle. The response of these tachycardias (VT) to flecainide was studied. Leads II, aVL, intraventricular right and left unipolar records, as well as one on the superior vena cava (SVC) were registered under control conditions, with VT and after the injection of this antiarrhythmic agent. This injection was infused into SVC over 15-20 minutes. Records were obtained with constant intervals, waiting for the recovery of sinus rhythm (SR) and the posterior reappearance of ventricular tachycardia. The experiments were performed 6 to 8 hs with continuous infusion of Hartmann' solutions. Throughout these periods, the variations of systemic systolic pressure were registered. Of the 22 dogs receiving 4 mg/kg of flecainide, transient SR was observed in 12 (55%), while in 4 (18%) this medication had no effect. Heart block presented in 2 animals and a fall of arterial pressure in 4. Of another 25 dogs receiving 2.5 mg/kg of flecainide, similar to clinical doses, transient SR appeared in 11 (44%), while in 3 (12%) SR was not observed. In other 2 groups, each of 15 dogs, the repeated antiarrhythmic action of flecainide was present in 33% with 4 mg/kg and in 20% with 2.5 mg/kg. This medication had no effect in 20% of the former and in 40% of the latter. However the low dose did not produce undesirable effects. Furthermore these differences were no significant statistically. Flecainide is effective in certain experimental ventricular tachycardias probably related to sodium-dependent potentials.
通过将乌头碱微小晶体注入梗死区域周边来诱发犬心实验性室性心动过速，梗死区域是通过在左心室心尖附近壁内注射1 - 1.5毫升苯酚产生的。研究了这些室性心动过速（VT）对氟卡尼的反应。在对照条件下、出现室性心动过速时以及注射这种抗心律失常药物后，记录II导联、aVL导联、心室内右和左单极记录以及上腔静脉（SVC）处的记录。该注射剂在15 - 20分钟内注入上腔静脉。以恒定间隔获取记录，等待窦性心律（SR）恢复以及室性心动过速再次出现。实验在持续输注哈特曼溶液的情况下进行6至8小时。在整个这些时间段内，记录体循环收缩压的变化。在接受4毫克/千克氟卡尼的22只犬中，12只（55%）观察到短暂窦性心律，而4只（18%）该药物无作用。2只动物出现心脏传导阻滞，4只出现动脉压下降。在接受2.5毫克/千克氟卡尼（类似于临床剂量）的另外25只犬中，11只（44%）出现短暂窦性心律，而3只（12%）未观察到窦性心律。在另外两组中，每组15只犬，接受4毫克/千克氟卡尼时，33%出现氟卡尼的重复抗心律失常作用，接受2.5毫克/千克时为20%。该药物在前一组的20%和后一组的40%中无作用。然而低剂量未产生不良影响。此外，这些差异在统计学上无显著意义。氟卡尼在某些可能与钠依赖性电位相关的实验性室性心动过速中有效。
