The Effect Of Different Position ARPES On Cardiac Function In Normal Rabbit

Object: Through observing the effect of absolute refractory period electrical stimulation(ARPES) on different positions (apex of right ventricle, left ventricular posterior wall) in normal rabbits'cardiac function, we want to study the exact mechanism of how it impacts the cardiac function.Methods: 24 healthy New Zealand white rabbits are randomly divided into three groups:(1)sham operation group: the rabbits were cuted thepericardium after the operation of thoracotomy without stimulation on the heart. (2)right ventricles stimulation group: after thoracotomy, the temporary pacing electrode used for children was sutured at the apex of right ventricle, and then ARPES was imposed on the rabbits'heart. We defined the RS stimulation as ARPES, which was triggered by the R-wave under the sinus rhythm and then the stimulus equipment sent stimulation after 30ms of the R-wave. Pacing voltage was 2 times of the diastolic threshold voltage. Pulse width was 2ms. The stimulation lasted for 6h. (3)left ventricular posterior wall group: after thoracotomy, the temporary pacing electrode used for children was sutured at left ventricular posterior wall. ARPES was provided as described above. The values of left ventricular end-diastolic dimension (LVEDD), left ventricular end-systolic dimension (LVESD) and left ventricular ejection fraction(LVEF) were measured respectively depending on before and after stimulation in three groups and so did the concentration of brain natriuretic peptide (BNP) which was measyred by ABC-ELISA method.Results:1 The result of brain natriuretic peptide1.1 The comparison amoung three groupsBefore stimulation, the difference of brain natriuretic peptide amoung the three groups is not statistically significant. Comparing with sham operation group, the brain natriuretic peptide is increased in right ventricles stimulation group and left ventricular posterior wall group after stimulation(P>0.05).The difference is statistically significant(P>0.05).But there is no difference between the two groups after short term stimulation(P>0.05).1.2 The comparison of before and after sugery in every group. After stimulation, brain natriuretic peptide has no difference in the sham operation group than before stimulation(P>0.05).But the brain natriuretic peptide is increased in right ventricles stimulation group and left ventricular posterior wall group than before stimulation. The difference is statistically significant(P<0.05) (Table1,Fig1).2 The results of echocardiography: LVESD,LVEDD and LVEF.2.1 The comparison among three groupsThere is no difference of all the dates in the three groups after stimulation when comparing with before(P>0.05).2.2 The comparison of before and after stimulation in every group.After stimulation, all the dates have no difference in three groups than before(P>0.05),( Table2,Fig2).Conclusion: ARPES short term stimulation has no obvious effect on normal systolic and diastolic function and the impact of different parts of heart was also no difference, but higher BNP concentration after stimulation may indicate increased myocardial contractility, and heart function was improved correspondingly.