Acute Effect Of Differernt Frequencies Of Spinal Cord Stimulation On Cardiac Function And Left Ventricular Remodeling In Rabbit With Heart Failure After Acute Myocardial Infarction

Objective: To investigate the effect of left ventricular remodeling andserum brain natriuretic peptide(BNP) level in rabbits with heart failure (HF)after acute myocardial infarction (AMI) undergoing spinal cord stimulationtherapy with different electrical frequencies.Methods:40New Zealand white rabbits weighing2.5-3.5Kg wereselected for left anterior descending artery ligation for the induction of HFafter AMI. Another20age-and weight-matched health rabbits with normalelectrocardiogram and with sham operation were used as controls. Everyrabbit was randomized to provide one of5Hz,50Hz and500Hz SCS therapy.Then crossed over to perform the other two frequencies of SCS separately.Detailed echocardiography parameters including LVEF、LVEDd、LVESd、FS、LAD、IVSd、LVPWd and E/Em were performed at basic state、4weekendand after different frequencies of SCS separately. The level of BNP was testedat basic state,4weekend and SCS completed.Results:1)Compared with before acute myocardial infarction andsham-operation group, the LVEDd、LVESd、LAD and E/Em increased and LVEF、FS、IVSd and LVPWd declined significantly in HF group,(P<0.05);Compared with before5Hz SCS in HF group, LVEDd and LVESd decreasedand LVEF and LVPWd increased after SCS completed (P<0.05). Comparedwith before SCS in HF group, LVEDd、LVESd、LAD and E/Em reduced andLVEF、FS、IVSd and LVPWd increased both in50Hz SCS and500Hz SCS(P<0.05); Compared with three frequencies of SCS each other,50Hz SCS hadhigher LVEF、FS、IVSd and LVPWd and lower LVEDd、LVESd、LAD andE/Em than5Hz SCS (P<0.05)；Meanwhile,50Hz SCS had higher LVEF、FS、IVSd and LVPWd and lower LVEDd、LVESd and E/Em than500Hz SCS(P<0.05); Moreover,500Hz SCS had higher LVEF and FS and lowerLVEDd、LVESd and E/Em than5Hz SCS (P<0.05); However, there was nosignificant defference on LV parameters between different frequencies SCS(P<0.05).2) Compared with HF group and sham-operation group, BNPincreased significantly in HF group at4weekend (P<0.05); After SCStreatment, BNP declined compared with before in HF group (P<0.05).3)The whole heart weight increased in HF group compared withsham-operation group(P＜0.05), and the ischemic myocardial weight was44.28±2.61g and peri-infarcted region was32.7±1.3%of the whole leftventricleConclusions: The spinal cord stimulation in rabbit model with HF afterAMI have the ability to timely improve systolic and diastolic function of leftventricle and decline the level of BNP, especially in the frequency of50Hz.The results demonstrated that SCS maybe down regulate the activity ofintrinsic cardiac sympathetic nervous system and improve cardiac function. Objective: this study sought to assess the effect of different electricalfrequencies of spinal cord stimulation on regional and global left ventricle(LV)short-axis strain and the time to peak radial strain(Trs) at papillary level inrabbits with HF after AMI.Methods:40New Zealand white rabbits weighing2.5-3.5Kg wereselected for left anterior descending artery ligation for the induction of HFafter AMI. Another20age-and weight-matched health rabbits with normalelectrocardiogram and with sham operation were used as controls. Everyrabbit was randomized to different electrical frequencies of SCS with5Hz、50Hz and500Hz. Regional and global myocardial radial strain(RS) andcircumferential strain(CS) and Trs and the time to peak circumferentialstrain(Tcs) at papillary level were detected by two-dimensional speckletracking image(STI) at baseline,4weekend and right off after each of thethree frequencies of SCS completed. And then got the ratios of standarddeviation of the Tcs to R-R interval and the ratios of the difference of Trsbetween anteroseptal and posterior(TAS-POST) to R-R interval.Results: Compared with the HF group before acute myocardialinfarction and sham-operation group, the RS、CS、GCs and GRs of the HFgroup were all reduced significantly(P<0.05).1)The measurement ofCS:compared with HF group before treatment, after5Hz SCS,only the CS ofanteroseptal and lateral were higher than before(P<0.05) and the GCs was notsignificantly improved(P<0.05); After50Hz and500Hz SCS, the CS of all the segments and the GCs were higher than before(P<0.05); Among the threefrequencies, the effect of50Hz was with the most significance than50Hz and500Hz. The measurement of RS: compared with HF group before treatment,after5Hz SCS,only the RS of anteroseptal、anterior and lateral were higherthan before(P<0.05) and the GCs was not significantly improved(P<0.05);After50Hz and500Hz SCS, the CS of all the segments and the GCs werehigher than before(P<0.05);Among the three frequencies, the effect of50Hzwas most significant than500Hz and5Hz.3)The measurement ofTcs-6SD/R-R:compared with HF group before treatment,the Tcs-6SD/R-Rwere all reduced after the three frequencies SCS. But only50Hz and500Hzhad significant difference (P<0.05), and50Hz was with better effect than500Hz (P<0.05).4)The measurement of TAS-POST/R-R:compared with HFgroup before treatment,the TAS-POST/R-R were all reduced after the threefrequencies SCS(P<0.05). the effect of50Hz was most significant than500Hzand5Hz, and500Hz was better than5Hz(P<0.05).Conclusions: The spinal cord stimulation can timely improve the GCs、GRs、CS and RS at papillary level in rabbit model of HF after AMI, and thesame time improve left ventricular synchrony. Among the three frequencies50Hz was with the most significant effect.