QTc, Tp-e Interval and Tp-e/QTc Ratio in Patients with Hypocalcemia-case Control Study

Abstract Background: To the best of our knowledge, there are studies related to QT and QTc interval in patients with hypocalcemia, but there are no studies evaluating T wave peak and end interval (Tp-e interval), Tp-e/QT and Tp-e/QTc ratios used to evaluate cardiac arrhythmia risk and ventricular repolarization changes rates. Objectives: Therefore, we aimed to investigate whether there is a change in Tp-e interval, Tp-e/QT and Tp-e/QTc ratios in patients with hypocalcemia. Methods: Retrospectively, 29 patients with hypocalcemia in the emergency department were included in the study. Twenty-nine patients with similar age and sex distribution were included in the study as the control group. All patients underwent 12-lead electrocardiography (ECG). In addition to routine measurements, Tp-e interval, Tp-e/QT and Tp-e/QTc ratios were measured on ECG. The study data were grouped as patients with and without hypocalcemia. Results: The mean age of the patients was 66.24 ± 4.95 years. QTc interval, Tp-e interval and Tp-e/QTc values were found to be significantly higher in patients with hypocalcemia (p <0.001 for each). QTc interval, Tp-e interval and Tp-e/QTc ratio showed a significant negative correlation with calcium levels. Conclusion: Tp-e interval and Tp-e/QTc ratios are significantly increased in patients with hypocalcemia compared to those without hypocalcemia and this can be used more effectively in the follow-up of cardiac fatal arrhythmias.

Effects of target-controlled infusion of propofol with different concentrations on ventricular repolarization after preoperative infusion of cefuroxime sodium in patients undergoing gynecologic opera-tion / 临床麻醉学杂志

Objective To investigate the effects of target-controlled confusion of propofol with different concentrations on ventricular repolarization after prophylactic infusion of cefuroxime sodium. Methods Sixty ASA physical status Ⅰ or Ⅱ female patients,aged 18-65 years,undergoing elective gynecological surgery were randomly divided into three groups:group P2 (n =20)with TCI 2 μg/ml, group P3 (n =1 9)with TCI 3 μg/ml and group P4 (n =20)with TCI 4 μg/ml.Firstly,they were re-hydrated;secondly,the patients in groups P2,P3 and P4 were intravenous infused with cefuroxime sodium 2.5 g (in 100 ml normal saline)and then target-controlled infused of propofol 2 μg/ml,3μg/ml and 4 μg/ml in target plasma concentration,respectively.At three pionts of time:after rehy-dration before intravenous antibiotics (T0 ),after intravenous antibiotics before TCI of propofol (T1 ), after TCI of propofol (T2 ),QT interval,QTc interval,Tp-e interval were measured and recorded, respectively.Results Compared with T0 ,QTc [(469.9 ± 34.0)ms vs.(451.2 ± 24.9)ms],Tp-e [(107±25)ms vs.(94±20)ms]and Tp-e/QT (0.260±0.058 vs.0.236±0.043)in group P4 were sig-nificantly prolonged at T1 (P < 0.05 ).Compared with T1 ,QTc of groups P2 [(437.4 ± 24.4)ms vs. (453.3±28.0)ms]and P4 [(438.8±29.9)ms vs.(469.9±34.0)ms]were shortened significantly at T2 (P <0.05).Conclusion Propofol could improve ventricular reporlarization heterogeneity caused by cefu-roxime sodium.

Prolonged Tp-e Interval, Tp-e/QT Ratio and Tp-e/QTc Ratio in Patients with Type 2 Diabetes Mellitus

BACKGROUND: Type 2 diabetes mellitus (T2DM) is associated with increased risk of malignant ventricular arrhythmias. Cardiac electrical inhomogeneity may be the leading cause of the increased arrhythmic risk in patients with T2DM. The peak and the end of the T wave (Tp-e) interval and associated Tp-e/QT ratio are promising measures of ventricular repolarization indicating transmural dispersion of repolarization. The aim of this study was to assess ventricular repolarization in patients with T2DM by using Tp-e interval, Tp-e/QT ratio and Tp-e/corrected QT interval (QTc) ratio. METHODS: Forty-three patients with T2DM and 43 healthy control subjects, matched by gender and age, were studied. All participants underwent electrocardiography (ECG) recording. PR, RR and QT intervals represents the ECG intervals. These are not abbreviations. In all literature these ECG intervals are written like in this text. Tp-e intervals were measured from 12-lead ECG. Rate QTc was calculated by using the Bazett's formula. Tp-e/QT ratio and Tp-e/QTc ratio were also calculated. RESULTS: Mean Tp-e interval was significantly prolonged in patients with T2DM compared to controls (79.4±10.3, 66.4±8.1 ms, respectively; P<0.001). We also found significantly higher values of Tp-e/QT ratio and Tp-e/QTc ratio in patients with diabetes than controls (0.21±0.03, 0.17±0.02 and 0.19±0.02, 0.16±0.02, respectively; P<0.001). There was no difference in terms of the other ECG parameters between the groups. CONCLUSION: Tp-e interval, Tp-e/QT ratio and Tp-e/QTc ratio were prolonged in patients with T2DM. We concluded that T2DM leads to augmentation of transmural dispersion of repolarization suggesting increased risk for ventricular arrhythmogenesis.

Effect of oxytocin on Tp-e and QTc interval during caesarean section / 中国医师进修杂志

Objective To evaluate the effect of oxytocin on Tp-e and QTc interval during caesarean section under spinal anesthesia in healthy puerperas. Methods Forty ASA Ⅰ puerperas were selected and allocated to receive oxytocin intravenous bolus group (group-IB) or oxytocin continuous infusion group (group-CI) with 20 puerperas in each by random digits table. An intravenous bolus of 5% glucose 5 ml and 5 U oxytocin was administered after delivery a 55-60 s period. A continuous infusion of 5% glucose 5 ml and 5U oxytocin was administered after delivery a 10 min period. Measured the QTc interval,Tp-e interval,mean arterial pressure (MAP) and beart rate ( HR ) pre-operatively, then 1,3 and 5 ain after spinal anesthesia, and at least 1,3,5 and 10 min after oxytocin injection. Results In group-IB:HR was fast 1 min after oxytocin injection compared with pre-operatively [(89 ± 13) beats/min vs. (73 ± 12) beats/min] ,MAP was decreased [(69 ± 12 ) mm Hg ( 1 mm Hg= 0. 133 kPa ) vs. ( 82 ± 13 ) mm Hg] and QTc interval was prolonged [(426 ±21 ) ms vs. (405 ± 18 ) ms] (P ＜ 0.01 ); but Tp-e interval was prolonged 1,3,5 min after oxytocin injection compared with pre-operatively (P ＜ 0.01 or ＜ 0.05 ). Conclusions Single large dose of oxytocin intravenous bolus (5 U) can prolong QTc interval and Tp-e interval in healthy puerperas, and Tp-e interval can exact predict the occurrence of ventricular arrhythmias. The risk-benefit balance of oxytocin bolus during caesarean delivery should be discussed with women with a history of long QT syndrome.