QT dispersion increases during intubation in patients with coronary artery disease

An Easy and Reliable Way to Prevent Electrocardiographic Deteriorations of Patients Undergoing Off-Pump Coronary Artery Bypass Surgery: Preoperative Anxiolytic Treatment

OBJECTIVE

To investigate the effects of preoperative anxiety relieving on electrophysiological changes in patients undergoing off-pump coronary artery bypass surgery.

METHODS

A total of 61 patients at ASA III risk group in the age range of 18-65 years were enrolled in the present study. Patients were randomly divided into two groups. Group S (Sedation group) was administered 0.04 mg/kg lorazepam per os (PO) twice before the operation. Group C (control group) was not administered with any anxiolytic premedication. State Trait Anxiety Inventory (STAI-I) and Beck Anxiety Inventory (BAI) were used to evaluate the level of anxiety. Electrocardiography (ECG), pulse oximeter and standard monitoring were performed for each patient. QT and P dispersions in each derivation of all ECGs were calculated.

RESULTS

Preoperative STAI-I scores were significantly lower in sedation group compared to the controls. Mean values of QT dispersion measured before induction, at the 1st minute of induction, 30th second of intubation and 4th minute of intubation in sedation group were significantly reduced compared to controls (P=0.024; P=0.027; P=0.001; P=0.033, respectively). The mean values of P dispersion measured before induction, at the 3rd minute of induction, 30th second of intubation and 4th minute of intubation in sedation group were significantly reduced compared to controls (P=0.001; P=0.020; P=0.023; P=0.005, respectively).

CONCLUSION

Elevated anxiety levels in patients undergoing coronary bypass surgery have a negative effect through prolonged QT and P-wave dispersion times. Anxiolytic treatment before surgery may be useful to prevent ventricular and atrial arrhythmias and associated complications through decreasing the QT and P-wave dispersion duration.

Effects of esmolol on QTc interval changes during tracheal intubation: a systematic review

INTRODUCTION AND AIMS

Esmolol is an ultra-short-acting β₁ antagonist that has been shown to attenuate the corrected QT (QTc) interval prolongation associated with laryngoscopy and endotracheal intubation (LTI). Prolongation of the QTc interval can precipitate arrhythmias, the most serious of which is torsades de pointes . The aim of this systematic review was to compare esmolol and placebo on QTc changes occurring during LTI.

MATERIALS AND METHODS

PubMed, EMBASE, Cochrane Registry of Clinical Trials and CINAHL databases (up to August 2018) were screened for randomised controlled trials comparing esmolol and placebo on QTc changes during LTI in cardiac and non-cardiac surgeries. The primary outcome was QTc changes during LTI and secondary outcome was related to adverse effects from esmolol such as bradycardia and hypotension.

RESULTS

Seven trials were identified involving 320 patients, 160 patients receiving esmolol or placebo apiece. A shortening of the QTc post-LTI was evident in the esmolol group compared with the placebo in four studies. Compared with the baseline, the QTc was reduced post-LTI in the esmolol group. In the placebo group, the QTc was prolonged compared with the baseline post LTI. Nonetheless, esmolol did not prevent QTc prolongation in the remaining three studies, and much of this was attributed to employing QTc prolonging agents for premedication and anaesthetic induction. No significant adverse events were noted.

CONCLUSION

Compared with placebo, esmolol reduced the LTI-induced QTc prolongation when current non-QTc prolonging agents were chosen for tracheal intubation. Future studies should explore whether transmural dispersion (a marker of torsadogenicity) is also affected during LTI by analysing parameters such as the Tp-e interval (interval between the peak to the end of the T-wave) and Tp-e/QTc (rate corrected Tp-e interval).

TRIAL REGISTRATION NUMBER

CRD42018090282.

The effects of intravenous anesthetics on QT interval during anesthetic induction with desflurane

Introduction

This study aimed to determine the effects of the interaction between intravenous anesthetics and desflurane on the QT interval.

Methods

Fifty patients who underwent lumbar spine surgery were included. The patients received 3 μg/kg fentanyl and were randomly divided into two groups: group P patients received 1.5 mg/kg propofol and group T patients received 5 mg/kg thiamylal 2 min after fentanyl injection. All patients received rocuronium and desflurane (6% inhaled concentration) after loss of consciousness. Tracheal intubation was performed 3 min after rocuronium injection. Heart rate (HR), mean arterial pressure (MAP), bispectral index score (BIS), and the heart rate-corrected QT (QTc) interval on a 12-lead electrocardiograms were recorded before fentanyl injection (T1), 2 min after fentanyl injection (T2), 1 min after propofol or thiamylal injection (T3), immediately before intubation (T4), and 2 min after intubation (T5).

Results

There were no significant intergroup differences in patient characteristics. BIS and MAP decreased after anesthesia induction in both groups. MAP values at T3, T4, and T5 in group T were higher than those in group P. HR did not change over time or differ between the groups. The QTc intervals at T4 and T5 in group T were longer than those at T1. In group P, the QTc interval at T3 was significantly shorter than that at T1. The QTc intervals at T3, T4, and T5 in group T were significantly longer than those in group P.

Conclusions

A propofol injection could counteract the QTc interval prolongation during desflurane anesthesia induction.

Trial registration

UMIN Clinical Trials Registry database reference number: UMIN000023707. This study was registered on August 21, 2016.

[Perioperative treatment of patients with long QT syndrome]

Long QT syndrome (LQTS) is caused by a change in cardiac repolarization due to functional ion channel dysfunction which is associated with an elongation of the QT interval (hence the name) in the electrocardiogram and a predisposition to cardiac rhythm disorders (e.g. torsade de pointes, TdP) as well as cardiac events up to sudden cardiac death. There is a congenital (cLQTS) and an acquired (aLQTS) form of the disease. The prevalence of cLQTS is 1 in 2000 but aLQTS is much more common and includes a grey area due to many asymptomatic patients. The LQTS is, therefore, more common than malignant hyperthermia which is much discussed in anesthesiology and has a reported prevalence in the population of 1:3000. Considering the prevalence of both aLQTS as well as cLQTS the importance of the LQTS seems to be underestimated in current perioperative care. Potential perioperative risks of such patients can be significantly reduced by appropriate patient management. This includes adequate preoperative preparation, the correct choice of anesthetic medication as well as adequate perioperative monitoring and preparedness for immediate pharmaceutical and electrical intervention in case of typical cardiac rhythm disturbances, such as TdP arrhythmia.

[The effect of esmolol on corrected-QT interval, corrected-QT interval dispersion changes seen during anesthesia induction in hypertensive patients taking an angiotensin-converting enzyme inhibitor]

BACKGROUND AND OBJECTIVES

The importance of minimizing the exaggerated sympatho-adrenergic responses and QT interval and QT interval dispersion changes that may develop due to laryngoscopy and tracheal intubation during anesthesia induction in the hypertensive patients is clear. Esmolol decreases the hemodynamic response to laryngoscopy and intubation. However, the effect of esmolol in decreasing the prolonged QT interval and QT interval dispersion as induced by laryngoscopy and intubation is controversial. We investigated the effect of esmolol on the hemodynamic, and corrected-QT interval and corrected-QT interval dispersion changes seen during anesthesia induction in hypertensive patients using angiotensin converting enzyme inhibitors.

METHODS

60 ASA I-II patients, with essential hypertension using angiotensin converting enzyme inhibitors were included in the study. The esmolol group received esmolol at a bolus dose of 500mcg/kg followed by a 100mcg/kg/min infusion which continued until the 4th min after intubation. The control group received 0.9% saline similar to the esmolol group. The mean blood pressure, heart rate values and the electrocardiogram records were obtained as baseline values before the anesthesia, 5min after esmolol and saline administration, 3min after the induction and 30s, 2min and 4min after intubation.

RESULTS

The corrected-QT interval was shorter in the esmolol group (p=0.012), the corrected-QT interval dispersion interval was longer in the control group (p=0.034) and the mean heart rate was higher in the control group (p=0.022) 30s after intubation. The risk of arrhythmia frequency was higher in the control group in the 4-min period following intubation (p=0.038).

CONCLUSION

Endotracheal intubation was found to prolong corrected-QT interval and corrected-QT interval dispersion, and increase the heart rate during anesthesia induction with propofol in hypertensive patients using angiotensin converting enzyme inhibitors. These effects were prevented with esmolol (500mcg/kg bolus, followed by 100mcg/kg/min infusion). During induction, the blood pressure tends to decrease with esmolol where care is needed.

Effects of High-Dose Rocuronium on the QTc Interval During Anaesthesia Induction in Patients Undergoing Coronary Artery Bypass Graft Surgery

OBJECTIVE

Existing myocardial damage in coronary artery disease patients causes prolonged QT syndrome. The primary objective of this trial is to explore the effects of different doses of the muscle relaxant agent rocuronium (0.6 mg kg(-1) and 1.2 mg kg(-1)) on QTc following anaesthetic induction. The second objective is to determine the incidence and kinds of arrhythmias.

METHODS

In this prospective and randomized trial, patients undergoing elective coronary artery revascularization surgery were included in one of two groups. Both groups took the same anaesthetic induction agents: midazolam and fentanyl. Rocuronium was administered in Group 1 (n=20) with dose of 0.6 mg kg(-1) and in Group 2 (n=20) with a dose of 1.2 mg kg(-1) for muscle relaxation. Heart rate, average arterial pressure and QTc were recorded before induction (T0), after induction (T1), after muscle relaxant (T2), and 2 minutes (T3) and 5 minutes after intubation (T4).

RESULTS

QTc was significantly longer 2 minutes after intubation (in Group 1 and Group 2, respectively, 447.9±28.3 and 466.1±37.8 ms) than at the beginning (respectively, 426.9±25.7, 432.0±35.5 ms) (p<0.01). In the intergroup comparison, average QTc values were similar in all trial periods (p>0.05). The prevalence of arrhythmias in between Group 1 (35%, n=7) and Group 2 (15%, n=3) was similar (p=0.06). Arrhythmias were recorded 2 minutes after intubation in both groups (n=10, 25%).

CONCLUSION

In patients undergoing coronary artery revascularization surgery, rocuronium doses of 0.6 mg kg(-1) and 1.2 mg kg(-1) prolong the QTc interval after intubation. Cardiac arrhythmias related to long QTc arising after intubation should be taken into consideration.

Differential effects of propofol and sevoflurane on QT interval during anesthetic induction

There have been conflicting reports on whether propofol prolongs, shortens, or does not change QT interval. The aim of this study was to determine the effect of target-controlled infusion (TCI) of propofol on heart rate-corrected QT (QTc) interval during anesthetic induction. We examined 50 patients undergoing lumbar spine surgery. Patients received 3 μg/kg of fentanyl and were randomly allocated to one of the following 2 groups. Group S patients received 5 mg/kg of thiamylal followed by sevoflurane, 5 % at the inhaled concentration. Group P patients received propofol using TCI system at 5 μg/mL for 2 min followed by 3 μg/mL. Tracheal intubation was performed after vecuronium administration. Heart rate (HR), mean arterial pressure (MAP), bispectral index score (BIS), and QTc interval in 12-lead electrocardiogram were recorded at the following time points: just before fentanyl administration (T1), 2 min after fentanyl injection (T2), 1 min after thiamylal injection or 2 min after the start of TCI (T3), just before intubation (T4), and 2 min after intubation (T5). BIS and MAP significantly decreased after anesthetic induction in both groups. HR decreased after anesthetic induction and recovered after tracheal intubation in group P, whereas it did changed in group S throughout the study period. QTc interval was shortened at T3 and T4 in group P, but prolonged at T3, T4, and T5 in group S, as compared with T1. Propofol TCI shortens QTc interval, whereas sevoflurane prolongs QTc interval during anesthetic induction.

A comparison of the effect on QT interval between thiamylal and propofol during anaesthetic induction*

SUMMARY

The aim of this study was to determine the effect of thiamylal and propofol on heart rate-corrected QT (QTc) interval during anaesthetic induction. We studied 50 patients undergoing lumbar spine surgery. Patients were administered 3 microgxkg(-1) fentanyl and were randomly allocated to receive 5 mgxkg(-1) thiamylal or 1.5 mgxkg(-1) propofol as an induction agent. Tracheal intubation was performed after vecuronium administration. Heart rate, mean arterial pressure, bispectral index score, and 12-lead electrocardiogram were recorded at the following time points: just before (T1) and 2 min after (T2) fentanyl administration; 2 min after anaesthetic administration (T3); 2.5 min after vecuronium injection (T4); and 2 min after intubation (T5). Thiamylal prolonged (p < 0.0001), but propofol shortened (p < 0.0001), the QTc interval.

Effects of Intravenous Lidocaine on QTd and HRV Changes Due to Tracheal Intubation During Sevoflurane Induction

The aim of the present study was to evaluate the effects of IV lidocaine on autonomic cardiac function changes in tracheal intubation (TI) during sevoflurane anaesthesia by using more reliable parameters, namely, the analysis of QT dispersion and heart rate variability (HRV) from Holter monitoring. In this prospective, double-blind study, 44 American Society of Anaesthesiologists class I-II patients scheduled for hysterectomy were randomly and equally divided into 2 groups; a control sevoflurane group (group S, n = 22) and a lidocaine sevoflurane group (group LS, n = 22). Before the induction of anaesthesia, the electrocardiograms (ECG) of all patients were recorded for 3 minutes as baseline parameters. In both groups, the anaesthesia was induced with 7% sevoflurane in O(2 )at 6L min(-1) via a facemask for 2 minutes. However, before the induction of sevoflurane anaesthesia in group LS, 1 mg kg(-1) of lidocaine was given intravenously (IV). For muscle relaxation during TI, vecuronium was given to all participants. Three minutes after administration of vecuronium, TI was performed and an ECG was recorded synchronously for another 3 minutes. The results from the later records were used as postintubation parameters. Baseline and postintubation data were analysed. When compared to baseline values, postintubation LF/HF and SDNN values were increased in group S (P = 0.005, P = 0.001, respectively), whereas postintubation LF and HF values were decreased in group LS (P = 0.014, P = 0.041, respectively). Under the influence of sevoflurane anaesthesia, TI resulted in sympathetic activation. However, this activation was attenuated by the administration of IV 1 mg kg(-1) lidocaine 5 minutes prior to TI.

Anaesthetics and the rate corrected interval: learning from droperidol?

PURPOSE OF REVIEW

Understanding of the long QT syndrome continues to evolve. Anaesthesia in patients with untreated long QT syndrome carries a risk of perioperative malignant ventricular arrhythmias. Genotypically susceptible individuals may have a normal rate-corrected QT interval and present with torsade de pointes intraoperatively. The likelihood of arrhythmias can be reduced by careful preoperative preparation. Perioperative disturbances in physiological homeostasis and drugs administered can prolong the rate-corrected QT interval.

RECENT FINDINGS

Seven ion channel genes have been discovered and over 300 mutations identified. For acquired long QT syndrome, the main issue is the blockade of a slow component of delayed rectifier potassium ion current. Preclinical tests are recommended to assess potential new drugs for QT prolongation. Drugs not increasing the transmural dispersion of repolarization have little potential to induce arrhythmias despite prolonging the QT interval. Diagnostic DNA testing is used to screen families. Although gene-based specific therapy is preliminary, molecular genetic analysis could be useful to unravel subclinical mutations. Future therapeutic strategies include the use of sodium antagonists, potassium channel activators and protein kinase inhibitors.

SUMMARY

Droperidol can lead to serious cardiac arrhythmias from QT prolongation. Recent advances in the pathophysiology of congenital and acquired long QT syndrome are reviewed. Preclinical tests assessing potential new drugs for QT prolongation are briefly discussed. Considerations for the management of these patients during perioperative phases are explored. The optimal treatment of the long QT syndrome is presented along with a glimpse into future possibilities in this field.