Severe QTc prolongation under mild hypothermia treatment and incidence of arrhythmias after cardiac arrest--a prospective study in 34 survivors with continuous Holter ECG

Background

Mild hypothermia treatment (32-34 °C) in survivors after cardiac arrest (CA) is clearly recommended by the current guidelines. The effects of cooling procedure towards QT interval have not been evaluated so far outside of case series. In a prospective study 34 consecutive survivors after cardiac arrest were continuously monitored with Holter ECG over the first 48 h.

Patients and methods

A total of 34 patients were analysed and received mild therapeutic hypothermia treatment (MTH) according to the current guidelines and irrespective of the initial rhythm. At admission to hospital and in the field in case of OHCA, a 12-lead ECG was performed in all patients.

Results

During cooling the incidence of ventricular tachycardia was low (8.8%) and in none of the patients Torsade de pointes occurred. The QTc interval was within normal range at first patient contact with EMS in the field (440.00 ms; IQR 424.25-476.75; n = 17) but during hypothermia treatment the QTc interval was significantly prolonged at 33 °C after 24 h of cooling (564.47 ms; IQR 512.41-590.00; p = 0.0001; n = 34) and decreased after end of hypothermia to baseline levels (476.74 ms; 448.71-494.97; p = 0.15).

Conclusion

The QTc interval was found to be significantly prolonged during MTH treatment, and some severe prolongations >670 ms were observed, without a higher incidence of life-threatening arrhythmias, especially no Torsade des pointes were detected. However, routine and frequent ECG recording with respect to the QTc interval should become part of any hypothermia standard operation protocol and should be recommended by official guidelines.     

环磷腺苷葡胺联合莫雷西嗪治疗室性心律失常的临床研究

目的探讨注射用环磷腺苷葡胺联合盐酸莫雷西嗪片治疗室性心律失常的临床疗效。方法选取2016年4月—2017年4月在海南省人民医院治疗的室性心律失常患者202例,根据用药的差别分为对照组(101例)和治疗组(101例)。对照组口服盐酸莫雷西嗪片,150 mg/次,3次/d;治疗组在对照组基础上静脉滴注注射用环磷腺苷葡胺,120 mg加入5%葡萄糖注射液250 mL,1次/d。两组患者连续治疗2周。观察两组患者临床疗效,同时比较治疗前后两组患者心率变异性指标和血清学指标。结果治疗后,对照组临床有效率为85.15%,显著低于治疗组的97.03%,两组比较差异具有统计学意义(P0.05)。治疗后,两组患者全程每5分钟NN节段的窦性RR间期标准差(SDANN)、全程连续窦性RR间期标准差(SDNN)、全程相邻RR之差的均方根(RMSSD)值均显著增加(P0.05),且治疗组患者SDANN、SDNN、RMSSD值明显大于对照组(P0.05)。治疗后,两组患者血清超敏C反应蛋白(hs-CRP)、肿瘤坏死因素-α(TFN-α)、白细胞介素-6(IL-6)、B型利钠肽(BNP)水平均显著降低(P0.05),且治疗组患者这些血清学指标水平明显低于对照组(P0.05)。结论注射用环磷腺苷葡胺联合盐酸莫雷西嗪片治疗室性心律失常的疗效显著,可有效改善心率变异性,降低机体炎症反应。     

Effects of nocturnal noninvasive mechanical ventilation on heart rate variability of patients with advanced COPD

BACKGROUND: Cardiovascular comorbidities have a negative impact on the health status and prognosis of patients with COPD. We determined whether nocturnal noninvasive (positive) mechanical ventilation (NIMV) can improve heart rate variability (HRV), decrease circulating natriuretic peptide levels, and improve functional performance of patients with very advanced COPD. METHODS: A randomized, double-blind, parallel controlled trial was conducted in 23 participants with stable but advanced COPD. Participants received standard medical therapy plus nocturnal NIMV or standard medical therapy plus sham NIMV for 3 months. RESULTS: After 3 months of NIMV therapy, the 24-h triangular interpolation of N-N intervals increased from 322 to 473 ms (p = 0.034), the 24-h HRV index (HRVI) increased from 21.8 to 29.9 ms (p = 0.035), nocturnal HRVI increased from 6.1 to 8.0 ms (p = 0.026), and the SD of the average N-N interval increased from 37 to 41 ms (p = 0.020). None of these indexes changed significantly in the control group. Additionally, compared with the control group, the pro-atrial natriuretic peptide levels declined significantly in the NIMV group (p = 0.013). CONCLUSIONS: NIMV applied nocturnally over 3 months may improve HRV, reduce circulating natriuretic peptide levels, and enhance the functional performance of patients with advanced but stable COPD. While not definitive due to small sample size, these data suggest that nocturnal NIMV may reduce the impact of cardiac comorbidities in COPD patients.     

芪麦强心汤联合西药治疗慢性心力衰竭随机平行对照研究

[目的]观察芪麦强心汤联合西药治疗慢性心力衰竭疗效。[方法]使用随机平行对照方法,将100例门诊及住院患者按随机数字表法分为两组。对照组50例常规西药治疗。治疗组50例芪麦强心汤(丹参20g,党参15g,田七、车前子、葶苈子各10g,麦冬15g),1剂/d,水煎100mL,早晚口服;西药治疗同对照组。连续治疗14d为1疗程。观测临床症状、TO、TS、SDNN、SADNN、不良反应。连续治疗2疗程,判定疗效。[结果]治疗组痊愈21例,显效16例,有效11例,无效2例,优秀率42.00%。对照组痊愈13例,显效12例,有效20例,无效5例,优秀率26.00%。治疗组疗效优于对照组(P0.05)。[结论]芪麦强心汤联合西药治疗慢性心力衰竭效果显著,值得推广。     

Different Trends of Changes in Heart Rate Variability in Patients with Anterior and Inferior Acute Myocardial Infarction

Modifications in heart rate variability (HRV) parameters occur after acute myocardial infarction. The aim of this study was to evaluate the trend of HRV change during the acute phase and the first month after myocardial infarction, and establish whether they were affected by the anterior or inferior location of the infarction. The time-domain HRV measures of 59 patients with a first uncomplicated acute myocardial infarction were computed from 24-hour ECG recordings made on days 1, 2, 10, and 28 after hospital admission. At day 1, the mean RR cycle length (NN), the standard deviation of the NN intervals (SDNN), and the root mean square successive difference of NN intervals (RMSSD) were lower in the patients with anterior myocardial infarction. Although the parameters were similar in all of the patients at day 28, their behavior over time was different (P = 0.01): the SDNN in the patients with inferior myocardial infarction had decreased to the values found in anterior myocardial infarction patients by day 2 but, at day 10, both NN and SDNN tended to recover in both groups; RMSSD had diminished in both groups by day 2, but at day 10, had increased in the patients with anterior, but not in those with inferior myocardial infarction. These findings suggest that (1) in the very early phase of myocardial infarction, HRV is different in the two locations, (2) during the first hours of myocardial infarction patients with inferior location showed a greater vagal activity than patients with anterior location that became lower at day 10, and (3) the recovery of HRV is an early phenomenon in both groups, being already evident by the second week after myocardial infarction.     

Impact of mercury exposure on blood pressure and cardiac autonomic activity among Cree adults (James Bay, Quebec, Canada)

Aboriginal populations from Quebec (Canada) are exposed to higher mercury levels than southern regions since these populations consume high quantities of fish. Epidemiological evidence suggests a detrimental impact of mercury on cardiovascular risk factors such as heart rate variability (HRV) and blood pressure (BP). The objective of this study was to assess the impact of mercury exposure on BP, resting heart rate (HR) and HRV among Cree adults. Data were collected among 791 adults ≥18 years old living in seven communities of the James Bay. Blood mercury and hair levels were used as biomarkers of recent and long-term exposure. BP was measured through a standardised protocol while HRV was derived from a 2-h Holter monitoring assessment. The relationship between mercury and the outcomes was studied using ANOVA and ANCOVA analysis. Geometric mean of blood mercury and hair mercury concentration was 17.0 nmol/L (95%CI: 6.1–44.0) and 2.36 nmol/g (95%CI: 2.09–2.65); respectively. After adjusting for confounders, blood mercury was associated with HRV parameters such as LF (β=0.21, P=0.0002), HF (β=0.15, P=0.004) and LF/HF (β=0.06, P=0.003). Similar associations were observed with hair mercury. In contrast, no significant association was observed between blood mercury or hair mercury and BP after adjusting for confounders. In conclusion, mercury exposure seems to affect HRV among Cree adults even after considering fish nutrients (n-3 fatty acids and selenium) and other contaminants (lead and polychlorinated biphenyls) that are also present in the traditional diet of this population.     

焦炉立火道温度的智能集成软测量方法及其应用

在分析焦炉立火道温度特性的基础上,提出了一种基于线性回归(LR)和监督式分布神经网络(SDNN)的立火道温度智能集成软测量方法。通过特性分析提出了典型蓄热室的选取原则,并利用级数验证了选取的有效性。为反映蓄顶温度与立火道温度的关系,首先分别建立了一元、二元和十二元LR模型,并通过智能集成将3个模型的输出进行有机融合;然后在对样本监督式聚类后,利用SDNN获得各个子网的综合输出;最后由专家协调器协调LR和SDNN的输出,得到立火道温度的软测量值。实际运行结果验证了该方法的有效性。     

AT1 antagonism by eprosartan lowers heart rate variability and baroreflex gain

INTRODUCTION: Blockade of the renin-angiotensin system (RAS) by ACE inhibitors has been demonstrated to reduce total mortality in cardiovascular diseases. This advantage was attributed in part to changes of autonomic cardiovascular control, exemplified by an increase of heart rate variability (HRV) and baroreflex gain (BRG). We sought to assess the effects of the angiotensin type 1 (AT1) receptor blocker eprosartan on HRV and BRG. MATERIALS AND METHODS: In a double-blind randomized cross-over design 25 young males took eprosartan (600 mg/day) and placebo each for a period of 7 days with a wash-out period of at least 4 weeks in between. At the end of the intake phases simultaneous recordings of arterial blood pressure (AP; Finapres) and electrocardiogram (ECG) were taken. Power spectra of HRV and arterial blood pressure variability (APV) were calculated by fast Fourier transform (FFT) and served to calculate BRG. Ang-II levels were measured by radioimmunoassay. RESULTS: Eprosartan tended to lower mean AP, it slightly increased heart rate (HR) (p<0.05), and markedly increased circulating Ang-II levels (p<0.01). Eprosartan diminished the total power of HRV (p<0.05) and the BRG (p<0.01). The low/high frequency (LF/HF) ratio of HRV and the APV were not altered. CONCLUSIONS: AT1 antagonism by eprosartan lowers heart rate variability and baroreflex gain. We speculate that these findings are due to the marked increase in circulating angiotensin II (Ang II). Further studies are needed to clarify whether angiotensin type 1 (AT1) blockers with potential actions inside the blood-brain barrier (BBB) may have different effects on HRV and BRG.