| Objective: To investigate the effects of different basic pacing rate on cardiac function in patients with chronic heart failure.Methods: Select 96 patients with chronic congestive heart failure(hereinafter abbreviated as CHF)transplanted pacemaker from July 2015 to July 2017 at Zhongshan hospital affiliated to dalian university.According to their NT-pro BNP,EF value,6-minute walking test and symptoms of CHF,patients are divided into two groups of ejection fraction reduced heart failure(LVEF value <45%)and ejection fraction preserved heart failure(LVEF value >50%).With external programmer controlling pacing rate,patients of the two groups are subdivided into 60 times/mine group,70 times/min group,80 times/min group,respectively.After 3 months,evaluate the NT-pro BNP and the 6 minute walking test again,assess cardiac function by ultrasonic cardiogram adopting "Vivid E9 with XDclear" type color Doppler echocardiography with transducer frequency of 2.5-4.0 MHz,and the receiver of left lateral position with eupnoea,synchronously recording electrocardiogram synchronously,and evaluating the cardiac parameters,including left ventricular ejection fraction(LVEF),Stroke volume(SV),Cardiac output(CO),Left ventricular end-diastolic diameter(LVEDD),Left ventricular early diastolic peak systolic velocity(E),Speed of mitral annulus(E'),Ratio of mitral early diastolic peak to speed of mitral annulus(E/E'),and left atrial volume index(LAVI);Finally,apply SPSS20.0statistical software in contrastive analysis,comparing the differences of cardiac function between patients suffering from chronic heart failure with reduced or preserved EF in groups of 60 times/min,70 times/min,80 times/min respectively.Results:(1)EF reduction group: The 6-minute walk test in all three groups was higher than that at the time of admission,Compared with 60 times/group,the growth rate of70 times/group was significantly increased(60 times/group 8.01 ± 1.23%,70 times/group 9.56±1.45%,P<0.05);80 times/group compared with 60/group showed a decreasing trend,but the difference was not statistically significant.In comparison of stroke volume,cardiac output,and EF value,the three groups of patients were all more advanced than those at admission,and compared with 60 times/group,the growth rate of 70 times/group stroke volume decreased significantly,with 80times/group growth rate was even lower(60 times/group 17.75 ± 3.77%,70/group16.43 ± 2.66%,P<0.05;80/group 14.22 ± 2.31%,P<0.01);and compared with60times/group,the growth rate of the 70 times/group cardiac output increased significantly(60 times/group 16.42±4.65%,70 times/group 17.13±4.74%,P<0.05),the 80 times/group growth rate showed a downward trend;compared with 60times/group,the growth rate of the 70 times/group EF value showed a downward trend,and the growth rate of 80 times/group was significantly lower than that of60times/group(60 times/group 6.58±1.74%,80 times/group 5.02±1.44%,P<0.01).At the end of follow-up,the ventricular diastolic function of the three groups of patients improved compared to admission,but the decline rate of 60 times/group's E/E' and LAVI was more significant,and the difference was statistically significant(E/E': 60 times/group 12.42 ± 3.49%,70 times/group 11.05 ± 3.61%,P<0.05,80 times/group 9.31±2.87%,P<0.01;LAVI: 60times/group 10.90±2.37 %,70 times/group 9.73±2.72%,P<0.05,80 times/group 7.84±1.63%,P<0.01).(2)EF preserved group: After 3 months,the 6-minute walk test in all three groups was higher than that at time of admission,Compared with 60 times/group,the growth rates of the70 times/group and 80 times/group 6 minute walking test showed a significant downward trend(60 times/group 10.02 ± 1.77%,70 times/group 9.01 ± 1.41%,P<0.05,80 times/group 7.89±1.39%,P<0.01).The stroke volume,cardiac output,and EF value of the three groups were higher than those at the time of admission.However,as the pacing rate increased,the growth rate showed a significant downward trend(stroke volume: 60 times/group 16.42±3.32%,70 times/group 14.38± 3.08%,P<0.01,80 times/group 13.02 ± 2.46%,P<0.01;cardiac output: 60times/group 17.03 ± 3.26%,70/group 15.52 ± 2.21%,P<0.05,80/group 14.13 ± 3.20%,P<0.01;EF: 60 times/group 7.15±2.11%,70 times/group 6.32±1.29%,P<0.05,80 times/group 4.48±1.44%,P<0.01).The diastolic function was improved in all three groups compared with admission,but diastolic function was gradually decreased in the three groups with the increase in pacing rate.The decline rate of 60times/group's E/E' and LAVI was more significant than 70 times/group and 80times/group(E/E': 60 times/group 14.40±2.38%.,70 times/group 10.33±2.74%,P<0.05,80 times/group 8.58±1.90%,P<0.01;LAVI: 60 times/group 13.59±2.64%,70 times/group 11.06±2.76%,P<0.01,80 times/group 9.45±2.62%,P<0.01).(3)In patients with the same pacing rate between the two groups,At a rate of 60 times per minute,the 6-minute walk test in the EF reduction group showed significantly lower growth rate than the EF preserved group(EF reduction group 8.01 ± 1.23%,EF preserved group 10.02±1.77% P<0.01).The growth rate of cardiac output and EF value in the EF reduction group were significantly lower than those in the EF preserved group(cardiac output: EF reduction group 16.42±4.65%,EF preserved group 17.03±3.26%,P <0.05;EF: EF reduction group 6.58 ± 1.74%,EF preserved group 7.15 ± 2.11%,P <0.05).(2)At a rate of 70 times per minute,the 6-minute walk test in the EF reduction group had a higher growth rate than the EF preserved group.The growth rate of stroke volume and cardiac output in the EF reduction group was significantly higher than that in the EF preserved group(stroke volume: EF reduction group 16.43±2.66%,EF preserved group 14.38±3.08%,P <0.05;cardiac output: EF reduction group 17.13 ± 4.74%,EF preserved group 15.52 ± 2.21%,P<0.05).Conclusion: 1.For patients with ejection fraction reduced heart failure,it will more effectively improve myocardial systolic function and cardiac output to increase the ventricular pacing appropriately.2.For patients with ejection fraction preserved heart failure,lower ventricular pacing will help to maintain a longer ventricular diastolic period,increase ventricular filling,increase the total cardiac output.For patients with different types of chronic heart failure after implantation of pacemakers,we must set their base pacing frequency more personalized. |
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