Effects of sevoflurane on QT parameters in children with congenital sensorineural hearing loss

Comparison of the Effects of Propofol and Sevoflurane on QT Interval in Pediatrics Undergoing Cochlear Implantation: A Randomized Clinical Trial Study

Background

Children with sensorineural hearing loss are at risk of cardiac electrophysiologic abnormalities. Inhalational Sevoflurane induction in these children can cause QT prolongation.

Objectives

In order to evaluate the safety of inhalational induction of anesthesia with sevoflurane in children with sensorineural hearing loss, who are candidates for cochlear implant, its electrophysiologic effects was compared with intravenous induction of anesthesia with propofol.

Methods

In this double-blind randomized clinical trial, 61 children aged between one and eighteen years old, who were candidates for cochlear implantation, were randomly allocated to groups receiving anesthesia with sevoflurane (n = 32) or propofol (n = 29) for induction of anesthesia. Two 12-leads ECG were taken from all of patients before and after induction and QTc, Tp-e interval, and JTc were measured and compared.

Results

Two cases, who had pre-induction QTc longer than 500 ms were excluded from the study. Patients had similar age (102.58 ± 87 versus 101.46 ± 67 months, P = 0.95) and gender (males: 48.3% versus 56.3%, P = 0.53) distribution. The researchers observed significant post induction difference in QTc values between these groups (propofol 422.5 ± 40, sevoflurane 445.0 ± 29, P = 0.016). There was no significant difference in the percent QTc and Tp-e changes in propofol and sevoflurane groups. Greater percentage of patients with increased Tp-e interval (> 100 ms) in the sevoflurane group than the propofol group was also seen. There was no significant long QTc difference (QTc > 500 ms or more than 60 ms increase from baseline) after induction of anesthesia in the sevoflurane group compared to the propofol group (15.6% versus 13.8%, P = 0.84).

Conclusions

After electrophysiological evaluations in children with sensorineural hearing loss, in patients whose pre-induction QTc is not longer than 500 ms, propofol seems safer than inhalational sevoflurane for induction of anesthesia.

The effect of sevoflurane on the transmural dispersion of repolarisation in patients with type 2 diabetes mellitus: a prospective observational study

The 'torsadogenic' property of a drug is linked to its ability to increase the transmural dispersion of repolarisation, represented by the interval between the peak of, and the end of, the T-wave (Tp-e interval) in an electrocardiogram. Reports have consistently shown that sevoflurane does not increase the Tp-e interval. Type 2 diabetes is a risk factor for increased QTc (rate-corrected QT interval), QTcd (rate-corrected QTc dispersion: difference between the maximum and the minimum QTc interval), and Tp-e, as well as the rate-corrected Tp-e (Tp-e/QTc ratio). The study aimed to ascertain whether sevoflurane increased the Tp-e interval and Tp-e/QTc ratio in patients with diabetes, thereby increasing their risk of torsades. We enrolled 35 female patients; 17 with type 2 diabetes and 18 controls undergoing non-laparoscopic surgery under sevoflurane anaesthesia. The Tp-e interval, Tp-e/QTc ratio, QTc and QTcd were recorded after intubation, 5, 10, 30 and 60 minutes into the anaesthetic, and were compared between the groups. No significant increase in the Tp-e interval or Tp-e/QTc was observed between or within the groups (a 13 ms increase was considered significant). In the control group, the QTc was significantly increased from baseline immediately after intubation (449 versus 414 ms, <i>P</i> <0.001); at 5 minutes (434 versus 414 ms, <i>P</i>=0.01); at 10 minutes (444 versus 414 ms, <i>P</i>=0.002); at 30 minutes (439 versus 414 ms, <i>P</i>=0.001) and at 60 minutes (442 versus 414 ms; <i>P</i> <0.001) (a 20 ms increase was considered significant). No significant increase in QTc was observed in the diabetic group. There were no between or within group differences observed for QTcd. Our findings suggest that sevoflurane does not have a significant predictable pro-arrhythmic effect in type 2 diabetic patients in the absence of other factors affecting ventricular repolarisation.

QT interval variability in body surface ECG: measurement, physiological basis, and clinical value: position statement and consensus guidance endorsed by the European Heart Rhythm Association jointly with the ESC Working Group on Cardiac Cellular Electrophysiology

This consensus guideline discusses the electrocardiographic phenomenon of beat-to-beat QT interval variability (QTV) on surface electrocardiograms. The text covers measurement principles, physiological basis, and clinical value of QTV. Technical considerations include QT interval measurement and the relation between QTV and heart rate variability. Research frontiers of QTV include understanding of QTV physiology, systematic evaluation of the link between QTV and direct measures of neural activity, modelling of the QTV dependence on the variability of other physiological variables, distinction between QTV and general T wave shape variability, and assessing of the QTV utility for guiding therapy. Increased QTV appears to be a risk marker of arrhythmic and cardiovascular death. It remains to be established whether it can guide therapy alone or in combination with other risk factors. QT interval variability has a possible role in non-invasive assessment of tonic sympathetic activity.

QT Variability Index

The QT Variability Index (QTVI) is a non-invasive measure of repolarization lability that has been applied to a wide variety of subjects with cardiovascular disease. It is a ratio of normalized QT variability to normalized heart rate variability, and therefore includes an assessment of autonomic nervous system tone. The approach assesses beat-to-beat variability in the duration of the QT and U wave in conventional surface electrocardiographic recordings, as well as determines the heart rate variability (HRV) from the same recording. As opposed to T wave alternans, QTVI assesses variance in repolarization at all frequencies. Nineteen studies have published data on QTVI in healthy individuals, while 20 have evaluated its performance in cohorts with cardiovascular disease. Six studies have assessed the utility of QTVI in predicting VT/VF, cardiac arrest, or cardiovascular death. A prospective study utilizing QTVI to determine therapy allocation has not been performed, and therefore the final determination of the value of the metric awaits definitive exploration.

The clinical significance of QT interval prolongation in anesthesia and pain management: what you should and should not worry about

The most feared drug-induced complication is fatal cardiac arrest. Torsades de pointes (TdP) is a polymorphic ventricular tachycardia occurring in the setting of a QT interval prolongation and is the most frequent type of drug-induced pro-arrhythmia. The most common mechanism of QT prolongation and TdP is blockade of the rapid component of the delayed rectifier repolarizing potassium conductance IKr. Anesthesiologists have extensive experience with QT prolonging drugs, but there are relatively few reports of TdP occurring in the perioperative setting. Nevertheless, regulatory concern regarding the drug droperidol resulted in a significant reduction in its use. Concern regarding two other agents that potently block IKr, i.e., sevoflurane and methadone, has grown, and practitioners are worried that these valuable agents may meet the same fate. In this review, the data regarding the TdP risk of droperidol, sevoflurane, and methadone are compared with particular emphasis on the different settings in which they are employed. While the three drugs are potent IKr inhibitors, little evidence exists to suggest that droperidol or sevoflurane are associated with significant proarrhythmia in the perioperative setting. Due to factors such as inhibition of the parasympathetic nervous system, prevention of hypoxia and hypercarbia, and attention to serum electrolytes, TdP is a very rare occurrence in the perioperative environment. Methadone, however, is typically given to outpatients, over long periods, and in combination with agents that inhibit its metabolism or are QT prolonging in their own right. Thus, pre- and post-drug electrocardiograms may be appropriate when prescribing methadone for outpatients, while the much lower risk for TdP (and the difficulties inherent in QT measurement in the perioperative period) render this approach unfruitful and worthy of reevaluation.