Sinus Bradycardia Crowd The Heart Of Change In Sexual Function Evaluation

PartⅠThe Evaluation of chronotropic response in a cohort of sinus bradycardia【Objective】To investigate the incidence of chronotropic incompetence (CI)in a cohort of sinus bradycardia and the value of exercise test(ET) and dynamic electrocardiogram(DCG)for diagnosis of CI.【Methods】Sixty seven subjects of sinus bradycardia(48 men and 19 women,mean age 46.7±13.9 years)and 47 control subjects of normal heart rate(34 men and 13 women,mean age 48.4±7.6 years)received treadmill exercise and DCG test.The maximal heart rate during ET and DCG were observed.CI was defined as the failure to achieve 85%of the age predicted maximal heart rate(APMHR)by ET or the maximal HR less than 100bpm by DCG.【Results】(1)Sixteen sinus bradycardia subjects(23.88%)and 4 normal control subjects(8.51%)achieved less than 85%of APMHR(p＜0.05). (2)The prevalence of CI using ET and DCG method was 23.88%and 7.46%respectively(p＜0.05)in the subjects of sinus bradycardia.【Conclusion】The population with sinus bradycardia has a higher incidence of chronotropic incompetence.ET is a more valuable diagnostic technique for CI than DCG. PartⅡThe relationship between chronotropic incompetence and autonomic nervous system【Objective】To investigate the relationship between chronotropic incompetence(CI)and autonomic nervous system.【Methods】Seventy five subjects of sinus bradycardia(52 men and 23 women,mean age 47.6±13.0 years)received treadmill exercise test(ET) and DCG.Plasma norepinephrine(NE)was measured at rest and maxima exercise.The changes in HR,METS and NE from the resting state to maxima exercise were calculated as△HR,△METS and△NE,respectively. The△NE was converted to a logarithmic scale(log△NE),△HR/log△NE was used as a parameter of HR response to sympathetic nerve stimulation. log△NE/exercise time was used as sympathetic activity to exercise.The maximal heart rate during ET and heart rate variability(HRV)of DCG were observed.CI was defined as the failure to achieve 85%of the age predicted maximal heart rate(APMHR).【Results】(1)HRV analysis between two groups:The LF/HF was significantly higher in subjects with CI compared with those without CI (1.80±0.50 vs 1.50±0.35,p=0.025).The SDNN,SDANN,RMSSD,PNN50,LF and HF were not significantly different between two groups. (2)△HR(68.67±16.12 vs 79.96±13.06,p=0.004),log△NE(2.68±0.50 vs 2.9±0.32,p=0.038),logNE_{max exercise}(0.77±0.25 vs 0.91±0.22, p=0.033),log△NE/△METS(0.0496±0.0604 vs 0.0797±0.0457, p=0.029)and log△NE/exercise time(0.050±0.064 vs 0.087±0.048, p=0.019)were significantly lower in patients with CI compared with those without CI.NE_{before exercise}(2.65±1.35 vs 3.23±1.82,p=0.217),exercise time(8.31±1.56 vs 7.96±1.56,p=0.408),△METS(8.88±1.75 vs 8.85±1.72,p=0.625),NE_{before exercise}/HR_{before exercise}(0.0469±0.0245 vs 0.0481±0.0276,p=0.868),NE_{max exercise}/HR_{max exercise}(0.0543±0.0273 vs 0.0625±0.0342,p=0.309)and△HR/log△NE(124.69±467.45 vs 138.85±210.32,p=0.859)were not significantly different between two groups.【Conclusion】The heart rate increasing by exercise is an index of sympathetic activity.Impaired sympathetic response may be an important reason for CI.