冠心病静息心率的变化及其临床意义研究

为探讨静息心率在冠心病中的变化及其临床意义。对 119例冠心病患者同时进行冠状动脉 (简称冠脉 )造影及静息心率的测定。结果 :冠心病组静息心率显著高于正常对照组 (79.11± 7.86vs 71.0 5± 6 .87次 /分 ,P <0 .0 5 ) ,在急性心肌梗死 (86 .77± 6 .76 )及不稳定型心绞痛组 (78.91± 8.30 )静息心率升高更明显 (P <0 .0 5 ) ,相关分析显示静息心率与冠脉的狭窄程度呈正相关 ,其中急性心肌梗死组静息心率与左前降支的狭窄程度呈显著正相关 ,P <0 .0 5。结论 :静息心率可能与动脉硬化的发生及冠心病的预后有关。     

Neurogenic Stress Cardiomyopathy in Heart Donors

Cardiac transplantation is severely restricted by donor availability. Left ventricular dysfunction due to neurogenic stress cardiomyopathy is often seen during donor evaluation and often presents a clinical dilemma for procurement. We report a case of a 23-year-old man with severe left ventricular dysfunction whose heart was successfully procured for transplantation. The brief case report is followed by an extensive review of neurogenic stress cardiomyopathy as well as donor evaluation for cardiac transplantation in the setting of such cardiomyopathy.     

Heart Rate and Heart Rate Variability in Normal Young Adults

Heart Rate and Heart Rate Variability. Introduction: The relationships between heart rate (HR) and HR variability (HRV) are not simple. Because both depend on the autonomic nervous system (ANS), they are not independent variables. Technically, the quantification of HRV is influenced by the duration of the cardiac cycles. The complexity of these relationships does not justify ignoring HK when studying HRV, as frequently occurs. Methods and Results: Using spectral and nonspectral methods, the HR and various normalized and non-normalized indices of HRV were studied in 24-hour recordings of a homogeneous cohort of seventeen 20-year-old healthy males. The HR-HRV relationships were appraised by analyzing the same data in two different ways. The 24 mean hourly values provide consistent information on the circadian behavior of the indices, while the average 24-hour individual data show a wide spectrum of normality. Combined approaches allow assessment of the direct impact of RR interval on HRV evaluation. The correlations between HR and normalized indices of HRV arc weaker in 24-hour individual data than in pooled hourly data of the same individuals. These correlations are close to 1 in the latter case, which does not mean that measuring HRV is simply another method of evaluating HR, but that normal physiology supposes a harmonious behavior of the various indices. When considered individually without normalization, the specific indices of vagal modulation (high-frequency band of the spectrum, short-term HR oscillations of the nonspectral analysis) consistently increase at night and diminish during the day. However, the low-frequency power, which supposedly reflects sympathetic influences, also increases at night, whereas more logically the longer HR oscillations would predominate during the day. Moreover, the selective analysis of HR oscillations during HR acceleration or decrease indicates that their behavior differs accordingly. Conclusion: We recommend that closer attention be paid to the complex relationships between HR and HRV. The strong correlations found in healthy subjects may reflect either the physiological harmony of ANS functions or simple redundancy. Their tendency to deteriorate in diseased hearts suggests that redundancy is not the cause and that abnormalities of ANS functions are not demonstrated by HRV analysis alone.     

Interaction between Heart Rate and Heart Rate Variability

Heart rate variability (HRV) is significantly associated with average heart rate (HR), therefore, HRV actually provides information on two quantities, that is, on HR and its variability. It is difficult to conclude which of these two plays a principal role in the HRV clinical value, or in other words, what is the HR contribution to the clinical significance of HRV. Moreover, the association between HRV and HR is both a physiological phenomenon and a mathematical one. The physiological HRV dependence on HR is determined by the autonomic nervous system activity, but the mathematical one is caused by the nonlinear relationship between RR interval and HR. By employing modification methods of the HRV and HR relationship, it is possible to investigate the HR contribution to the HRV clinical value. Recent studies have shown that the removal of the HR impact on HRV makes HRV more predictive for noncardiac death, however, the enhancement of this impact causes HRV to be a better predictor of cardiovascular mortality. Thus, HR seems to constitute a cardiovascular factor of the HRV predictive ability. HR also influences the reproducibility of HRV, therefore, HR changes should be considered when one compares HRV measurements in a given patient. This review summarizes methodological aspects of investigations of the HRV and HR interaction as well as latest observations concerning its clinical utility. The issues discussed in this article should also refer to any other heart rate dynamics analysis which indices are significantly associated with HR.     

Changes of Heart Rate Variability After Coronary Bypass Grafting

Background: Heart rate variability (HRV) may serve as a follow-up parameter in patients with coronary artery disease undergoing percutaneous transluminal angioplasty. Several studies have shown significant changes of HRV parameters in the case of restenosis. The value of this method as a prognostic parameter in patients following coronary artery bypass grafting (CABG) is unknown. Methods: In the present study we investigated changes of HRV parameters in patients undergoing CABG to prove whether this method would predict the outcome in these patients. Twenty patients (six female, 14 male, age 51–75 years, mean 62 years) with angiographically documented coronary artery disease (1 × 1-vessel disease, 10 × 2-vessel disease, 9 × 3-vessel disease) were investigated. Eight patients had previous myocardial infarction: 3 × anterior infarction and 5 × inferior infarction. Before and after CABG 24-hour measurement of HRV was performed using Holler monitoring (elapsed time between the two measurements 218 ± 92 days). All patients underwent successful CABG with complete revascularization. The following time domain parameters were calculated: SDNN, SDNN index, SDANN, r-MSSD and pNN50. Results: These parameters showed a significant decrease after CABG (P < 0.05) except rMSSD, which was below the statistic level. The results of the patients without previous myocardial infarction suggested that the parasympathetically influenced paramenters r-MSSD and pNN50 were mainly involved, while in the subgroup with previous myocardial infarction the sympathetically influenced parameters (SDNN, SDANN) were significantly changed. Other variables such as ejection fraction or severity of coronary artery disease did not influence the HRV results. Conclusions: In contratst to patients with revascularization by PTCA, HRV does not seem to be a suitable predictive parameter in patients after successful CABG. Intrinsic operative alterations with injury of cardiac nerves may be responsible for this observation.     

Heart Rate and Blood Pressure Changes during Gastroscopy in Healthy Older Subjects

BACKGROUND: Previous studies uncontrolled for co-morbidity have shown increased heart rate and decreased oxygenation during gastroscopy in older people. One previous study of selected younger patients suggested that changes in blood pressure were more pronounced in non-premedicated patients. AIMS: To prospectively examine blood pressure and heart rate responses during gastroscopy in healthy older people uninfluenced by medication or co-morbidity. METHODS: Blood pressure and heart rate were monitored continuously in consecutive unselected patients attending for gastroscopy carried out by one endoscopist. RESULTS: Thirty-seven patients were included with a mean age of 51.5 years (95% CI: 17-89); 10 patients were over the age of 65. During gastroscopy there were large increases in blood pressure and heart rate, with maximum changes occurring predominantly at intubation in the younger age group. Typically, increases in blood pressure in the older group occurred later in the procedure and were more sustained. Mean (95%CI) maximum changes in systolic blood pressure were more profound in those sedated [73 (55-91) mm Hg] compared to those having throat spray [47 (34-60) mm Hg; p < 0.05]. Maximum changes in heart rate during gastroscopy became significantly smaller with advancing age in those having throat spray (p = 0.03) but not in those receiving sedation. CONCLUSIONS: Gastroscopy stimulates blood pressure and heart rate changes that are greatest in those sedated. Further studies of the effect of gastroscopy upon blood pressure are required, particularly in older patients, the group regarded as at increased risk from complications.     

心率和心率变异性与心力衰竭及预后的相关性

目的　探讨心率及心率变异性与心力衰竭及预后的相关性。方法　入选2010年10月至2012年6月期间就诊宁夏医科大学总医院心内科的慢性充血性心力衰竭患者245例,根据住院期间平均静息心率水平分为3组：A组：50～70次/分;B组：71～90次/分;C组：＞90次/分;共随访1年,完成随访共230例。其中共有97例行动态心电图检查,按患者心功能分级分为Ⅱ级组、Ⅲ级组、Ⅳ级组,同时选择26例正常健康人为对照组。收集上述研究对象的心率变异性时域指标进行对比分析,包括正常RR间期标准差（SDNN）、5　min均值标准差（SDANN）、相邻RR间期相差＞50　ms的个数占总心跳数的百分比（PNN50）、全程相邻RR间期之差的平方根（RMSSD）。结果随着心率水平增加,随访终点射血分数明显降低,再住院率及病死率明显增加（P＜0.01）。不同心率水平心力衰竭患者Cox生存分析显示心率越快,生存率越低。心力衰竭组与对照组相比SDNN、SDANN、PNN50、RMSSD降低（P＜0.01或P＜0.05）,随着心力衰竭程度的加重,SDNN、SDANN、PNN50、RMSSD下降越明显（P＜0.01）。结论　心率越快,心力衰竭预后越差;心力衰竭患者存在心率变异性降低,心率变异性越低,心功能越差。     

Postprandial Changes of Sympathovagal Balance Measured by Heart Rate Variability

The aim of this study was to investigate thesympathovagal balance after meals by measuring thespectral analysis of heart rate variability (HRV). Ninehealthy volunteers were enrolled in this study. The electrocardiogram (ECG) was recorded for 30 minin a fasting state and 60 min after a 500-kcal testmeal. The HRV was derived from the ECG and was measuredby power spectral analysis using fast-Fourier transform algorithm. It reveals two dominantspectral components. The low-frequency (LF) bandreflects primarily sympathetic activity with someparasympathetic input. The high-frequency (HF) band isa reflection of parasympathetic (vagal) activity. TheLF-to-HF ratio is considered a marker of sympathovagalbalance. It was found that the postprandial LF-to-HFratio, compared with the fasting state, wassignificantly increased at both the first 30 min (2.50± 0.49 vs 1.78 ± 0.33, P < 0.05) andthe second 30 min (2.68 ± 0.55 vs 1.78 ±0.33, P < 0.05). The postprandial HF diminishedsignificantly at both the first (16.0 ± 0.5 vs 21.8 ±4.2, P < 0.05) and the second (13.8 ± 9.5 vs21.8 ± 4.2, P < 0.05) 30-min period. Inconclusion, the postprandial sympathovagal ratio showsa sustained elevation lasting 1 hr, mainly attributed to diminishedvagal activity.     

Heart Rate Variability in Heart Failure

The autonomic nervous system has an important role in the development and progression of the heart failure syndrome. Increased sympathetic, reduced parasympathetic, and impaired baroreceptor activity are well-documented features of heart failure. The analysis of heart rate variability can give insight into these autonomic abnormalities. A number of techniques now exist for assessing heart rate variability, and in general they reflect the known autonomic abnormalities. Power spectral analysis of RR variability has been claimed to reflect sympathovagal balance, but the reduced or absent low-frequency component in heart failure is paradoxical. It is likely that the absent low-frequency component in heart failure reflects impaired baroreceptor function. Although these various techniques of heart rate variability may be useful, reliability and reproducibility are problematic in this area. Better, more refined techniques for the noninvasive assessment of autonomic and baroreceptor function are still needed.     

睡眠呼吸暂停低通气综合征患者窦性心率震荡的变化

目的:了解睡眠呼吸暂停低通气综合征(SAHS)患者窦性心率震荡的变化。方法:对75例患者进行整夜(>7 h)多导睡眠仪监测,同时同步进行24 h动态心电图检查。根据多导睡眠仪监测结果得出睡眠呼吸暂停低通气指数(AHI),分别作出有无SAHS的诊断,将研究对象分为SAHS组(AHI≥5,n=52)与对照组(AHI<5,n=23),比较两组患者窦性心率震荡参数—震荡初始值(TO)、震荡斜率值(TS)的变化。结果:SAHS组较对照组震荡斜率值明显下降,差异有统计学意义(P<0.01)。两组震荡初始均值均<0,SAHS组>对照组,但差异无统计学意义,SAHS组24 h室性早搏的数量高于对照组,但差异无统计学意义。结论:SAHS组与对照组相比存在窦性心率震荡减弱现象,表明SAHS患者自主神经功能受损,震荡斜率降低可能作为预测SAHS患者发生心血管事件的一项指标。     

自主神经系统在阵发性心房颤动发作前后心率变异性变化中的作用

目的分析阵发性心房颤动发作前后心率变异性的变化,探讨自主神经系统在阵发性心房颤动中的作用。方法采用动态心电图记录28例阵发性心房颤动患者24h心电信息,分析其发作前后5min及白天（6：00～22：00）和夜间（22：00～6：00）的心率变异性指标。结果心房颤动发作前5min平均正常R—R间期的标准差（SDNN）、高频成份（HF）较终止后5min显著升高（P〈0．01）,低频／高频比值（LF／HF）显著降低（P〈0．01）,LF无变化：LF、HF白天均高于夜间（P〈0．01）,白天与夜间SDNN、LF／HF无差异;阵发性心房颤动发作前5minSDNN与阵发性心房颤动发作频率呈正相关（r=0．545。P〈0．01）,LF／HF与阵发性心房颤动发作频率和持续时间呈负相关（r=-0532、-0．563,均P〈0．01）。结论阵发性心房颤动发作前心率变异性升高,迷走神经支配占优势,使心房颤动得以诱发和持续。     

Vagal Nerve Stimulation Evoked Heart Rate Changes and Protection from Cardiac Remodeling

This study investigated whether vagal nerve stimulation (VNS) leads to improvements in ischemic heart failure via heart rate modulation. At 7?±?1 days post left anterior descending artery (LAD) ligation, 63 rats with myocardial infarctions (MI) were implanted with ECG transmitters and VNS devices (MI?+?VNS, N?=?44) or just ECG transmitters (MI, N?=?17). VNS stimulation was active from 14?±?1 days to 8?±?1 weeks post MI. The average left ventricular (LV) end diastolic volumes at 8?±?1 weeks were MI?=?672.40 μl and MI?+?VNS?=?519.35 μl, p?=?0.03. The average heart weights, normalized to body weight (±std) at 14?±?1 weeks were MI?=?3.2?±?0.6 g*kg^?1 and MI?+?VNS?=?2.9?±?0.3 g*kg^?1, p?=?0.03. The degree of cardiac remodeling was correlated with the magnitude of acute VNS-evoked heart rate (HR) changes. Further research is required to determine if the acute heart rate response to VNS activation is useful as a heart failure biomarker or as a tool for VNS therapy characterization.     

Heart Rate in Coronary Syndromes and Heart Failure

In the past 2 decades, there have been growing evidences that resting heart rate might be a marker of risk or even a risk factor for cardiovascular morbidity and mortality. This article reviews current evidences concerning the relation between heart rate and patients' outcome in different clinical settings such as acute coronary syndromes, left ventricular systolic dysfunction, and heart failure. The relationship between resting heart rate and the development of coronary artery disease, as well as all-cause and cardiovascular mortality, has been found to be strong, graded, and independent from other risk factors. Several lines of research indicate that heart rate plays an important role in the pathophysiology of atherosclerosis and in the clinical manifestations of coronary artery disease and that it is an independent prognostic factor in all coronary syndromes. The prognostic value of elevated heart rate in patients with heart failure has been tested in several clinical trials evaluating pharmacologic heart rate–lowering agents (eg, β-blockers). It is difficult to determine which percentage of the clinical benefit obtained with β-blockers is related to induced bradycardia because cardiac slowing is only one of the effects of these drugs. In the BEAUTIFUL trial, a subgroup analysis conducted in patients with resting HR more than 70 beats per minute showed that treatment with ivabradine was able to improve outcome. According to the results presented in this review, we can conclude that heart rate is a predictor of death in both stable coronary artery disease and acute coronary syndromes. Elevated heart rate is also able to negatively predict clinical outcomes in patients with heart failure. However, it is still unclear if heart rate reduction per se can improve prognosis.     

原发性高血压患者窦性心率震荡与心率变异性

目的 检测单纯原发性高血压(EH)患者窦性心率震荡(HRT)及心率变异性(HRV).方法 EH患者60例和健康人50例分别为高血压组和对照组,亚组研究分析降压治疗 倍他洛克组和降压治疗组的HRT与HRV.根据24 h动态心电图记录资料,分别计算各组HRT的两个参数震荡初始值(TO)和震荡斜率值(TS)以及HRV的全部NN间期的标准差(SDNN)、全部相邻NN间期之差的均方根值(RMSSD)和低频/高频(LF/HF).结果 1)高血压组TO、TS、TO TS、SDNN、RMSSD及LF/HF分别为:52、48、46、42、41、38例;对照组分别为:2、3、0、5、1、3例;高血压组上述6种指标的阳性检出率均高于对照组(P<0.01);2)降压治疗 倍他洛克组及降压治疗组TO、TS、TO TS阳性检出率差异无统计学意义,降压治疗 倍他洛克组的SDNN、RMSSD及LF/HF分别为:12、13、9例;降压治疗组分别为:30、28、29例,降压治疗 倍他洛克组SDNN、RMSSD及LF/HF的阳性检出率明显低于降压治疗组(P<0.01).结论 单纯EH患者有显著的HRT减弱及HRV的异常,HRT现象不受β受体阻滞剂的影响.     

原发性高血压患者窦性心率震荡与心率变异性

目的检测单纯原发性高血压(EH)患者窦性心率震荡(HRT)及心率变异性(HRV)。方法 EH 患者60例和健康人50例分别为高血压组和对照组,亚组研究分析降压治疗+倍他洛克组和降压治疗组的 HRT 与HRV。根据24 h 动态心电图记录资料,分别计算各组 HRT 的两个参数震荡初始值(TO)和震荡斜率值(TS)以及HRV 的全部 NN 间期的标准差(SDNN)、全部相邻 NN 间期之差的均方根值(RMSSD)和低频/高频(LF/HF)。结果 1)高血压组 TO、TS、TO+TS、SDNN、RMSSD 及 LF/HF 分别为:52、48、46、42、41、38例;对照组分别为:2、3、0、5、1、3例;高血压组上述6种指标的阳性检出率均高于对照组(P<0.01);2)降压治疗+倍他洛克组及降压治疗组 TO、TS、TO+TS 阳性检出率差异无统计学意义,降压治疗+倍他洛克组的 SDNN、RMSSD 及 LF/HF 分别为:12、13、9例;降压治疗组分别为:30、28、29例,降压治疗+倍他洛克组 SDNN、RMSSD 及 LF/HF 的阳性检出率明显低于降压治疗组(P<0.01)。结论单纯 EH 患者有显著的 ...     

肾上腺髓质素与神经肽Y在慢性心率增快心力衰竭患者中的变化及临床意义

目的　观察存在慢性心率增快的慢性心力衰竭患者血浆肾上腺髓质素（ADM）、神经肽Y（NPY）水平变化及临床意义,进一步探讨其在慢性心率增快中的作用。方法　将2011～2012年收住我院的慢性心力衰竭患者,根据患者入院时24　h动态心电图结果分为慢性心率增快组：80例,平均心率≥80次/分；非慢性心率增快组：80例,平均心率＜80次/分。使用酶联免疫吸附法测定两组慢性心力衰竭患者的血浆ADM、NPY、脑钠肽水平，用超声心动图测量左心房内径、左心室舒张末内径、左心室射血分数、左心室短轴缩短率。结果　慢性心率增快组慢性心力衰竭患者的血浆ADM、NPY水平均高于非慢性心率增快组（P<0.05）,随NYHA分级逐级增高，差异有统计学意义（P<0.01）。单因素分析显示ADM、NPY水平与左心房内径呈正相关（P<0.001），与左心室射血分数、左心室短轴缩短率呈负相关（P<0.001）。结论　ADM、NPY可能参与了慢性心力衰竭中慢性心率增快的病理生理过程，是心力衰竭恶化的危险因素。