Sevoflurane progressively prolongs the QT interval in unpremedicated female adults:

Efficacy and safety of propofol in preventing emergence agitation after sevoflurane anesthesia for children

Application of propofol in preventing emergence agitation after sevoflurane anesthesia in children was evaluated. Clinical data of 200 children who received sevoflurane anesthesia in Children's Hospital of Xuzhou Medical University were retrospectively analyzed. Among them, 120 patients who received inhaled sevoflurane for pediatric anesthesia and intravenous infusion of propofol (2 mg/kg) were included in observation group. The remaining 80 cases who were directly anesthetized by sevoflurane alone were the control group. T PAED scores, modified Aldrete scores, extubation time, PACU time and adverse reactions (gastrointestinal tract and respiratory response) were analyzed and compared between the control and observation group. PAED scores, extubation time, PACU time and incidence of adverse reactions were significantly lower in observation than in control group, and the modified Aldrete scores were higher in observation than in control group (P<0.05). Spearman's correlation analysis showed that the PAED scores were negatively correlated with modified Aldrete scores and positively correlated with extubation time. There was positive correlation between the PACU time and incidence of adverse reactions and between the PAED scores and extubation time. There was negative correlation between PACU time and incidence of adverse reactions and between Aldrete scores and extubation time (P<0.05). Therefore, we conclude that propofol can be used to prevent agitation after sevoflurane anesthesia in children.

Anaesthetists’ Knowledge of the QT Interval in a Teaching Hospital

Many drugs used in anaesthesia may prolong the QT interval of the electrocardiogram (ECG), and recent U.S. Food and Drug Administration guidelines mandate monitoring of the ECG before, during and after droperidol administration. We surveyed 41 trainee and consultant anaesthetists in our Department to determine current practice and knowledge of the QT interval to investigate if this is a practical proposition. A response rate of 98% (40/41) was obtained. The majority of respondents expressed moderate to high levels of confidence in interpreting the ECG, and this was related to years of training (rho 0.36, P=0.024). A total of 27 respondents (65%) were able to correctly identify the QT interval on a schematic representation of the ECG, trainees 70% vs consultants 60%, P=0.51. When asked to name drugs that altered the QT interval, droperidol was included by 11 of the 40 respondents (28%); trainees 10% vs consultants 45%, OR 7.4 (95% CI: 1.3–41), P=0.013. Torsades de Pointes was correctly identified as a possible consequence of a prolonged QT interval by 65% of trainees and 70% of consultants, P=0.83. The results suggest that QT interval measurement is not widely practised by anaesthetists, although its clinical significance is well known, and interpretation would be unreliable without further education.

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.

A Comparison of the Effects of Sevoflurane and Desflurane on Corrected QT Interval Prolongation in Patients Undergoing Living Donor Liver Transplantation: A Prospective Observational Study

BACKGROUND

QT interval prolongation has frequently been observed in patients with advanced liver disease. We investigated the influence of inhalation anesthetics on the corrected QT (QTc) interval prolongation during surgery in patients undergoing living-donor liver transplantation.

METHODS

Our study included 43 patients who were assigned to 2 groups: sevoflurane (n = 22) or desflurane anesthesia (n = 21). QTc intervals were measured at perioperative determined time points and calculated using Fridericia's formula.

RESULTS

Intraoperative QTc intervals increased during the peri-intubation period versus baseline (P = .003) and were prolonged during the peri-reperfusion period (P < .001). However, there was no significant difference in intraoperative QTc interval changes between patients given sevoflurane or desflurane (P = .59).

CONCLUSIONS

In this prospective observational study, there was no significant difference in QTc intervals between sevoflurane and desflurane. QTc intervals increased during intubation and reperfusion relative to preoperative values in patients given either sevoflurane or desflurane.

Intravenous palonosetron increases the incidence of QTc prolongation during sevoflurane general anesthesia for laparotomy

Background

Palonosetron is a recently introduced 5-hydroxytryptamine-3 (5-HT₃) receptor antagonist useful for postoperative nausea and vomiting prophylaxis. However, 5-HT₃ receptor antagonists increase the corrected QT (QTc) interval in patients who undergo general anesthesia. This retrospective study was performed to evaluate whether palonosetron would induce a QTc prolongation in patients undergoing general anesthesia with sevoflurane.

Methods

We reviewed a database of 81 patients who underwent general anesthesia with sevoflurane. We divided the records into palonosetron (n = 41) and control (n = 40) groups according to the use of intraoperative palonosetron, and analyzed the electrocardiographic data before anesthesia and 30, 60, 90, and 120 min after skin incision. Changes in the QTc interval from baseline, mean blood pressure, heart rate, body temperature, and sevoflurane concentrations at each time point were compared between the two groups.

Results

The QTc intervals at skin incision, and 30, 60, 90, and 120 min after the skin incision during general anesthesia were significantly longer than those at baseline in the two groups (P < 0.001). The changes in the QTc intervals were not different between the two groups (P = 0.41). However, six patients in the palonosetron group showed a QTc interval > 500 ms 30 min after skin incision, whereas no patient did in the control group (P = 0.01). No significant differences were observed between the two groups in mean blood pressure, body temperature, heart rate, or sevoflurane concentrations.

Conclusions

Palonosetron may induce QTc prolongation during the early general anesthesia period with sevoflurane.

The effect of beta1-adrenergic receptor gene polymorphism on prolongation of corrected QT interval during endotracheal intubation under sevoflurane anesthesia

Background

The hemodynamic responses to endotracheal intubation are associated with sympathoadrenal activity. Polymorphisms in the beta1-adrenergic receptor (β₁AR) gene can alter the pathophysiology of specific diseases. The aim of this study is to investigate whether the Ser49Gly and Arg389Gly polymorphism of the β₁AR gene have different cardiovascular responses during endotracheal intubation under sevoflurane anesthesia.

Methods

Ninety-one healthy patients undergoing general anesthesia were enrolled. Patients underwent slow inhalation induction of anesthesia using sevoflurane in 100% oxygen. Vecuronium 0.15 mg/kg was given for muscle relaxation. Endotracheal intubation was performed by an anesthesiologist. The mean arterial pressure (MAP), heart rate (HR), and the corrected QT (QTc) interval were measured before induction, before laryngoscopy, and immediately after tracheal intubation. Genomic DNA was isolated from the patients' peripheral blood and then evaluated for the β₁AR-49 and β₁AR-389 genes using an allele-specific polymerase chain reaction method.

Results

No differences were found in the baseline values of MAP, HR, and the QTc interval among β₁AR-49 and β₁AR-389, respectively. In the case of β₁AR-49, the QTc interval change immediately after tracheal intubation was significantly greater in Ser/Ser genotypes than in Ser/Gly genotypes. No differences were observed immediately after tracheal intubation in MAP and HR for β₁AR-49 and β₁AR-389.

Conclusions

We found an association between the Ser49 homozygote gene of β₁AR-49 polymorphism and increased QTc prolongation during endotracheal intubation with sevoflurane anesthesia. Thus, β₁AR-49 polymorphism may be useful in predicting the risk of arrhythmia during endotracheal intubation in patients with long QT syndrome.

Anesthesia induction with sevoflurane and propofol: evaluation of P-wave dispersion, QT and corrected QT intervals

The present study compared the effects of anesthesia induction with sevoflurane and propofol on hemodynamics, P-wave dispersion (Pwd), QT interval and corrected QT (QTc) interval. A total of 72 adult patients were included in this prospective study. All patients had control electrocardiograms (ECGs) before anesthesia induction. Anesthesia was induced with sevoflurane inhalation or intravenous propofol. Electrocardiography for all patients was performed during the 1(st) and 3(rd) minutes of induction, 3 minutes after administration of muscle relaxant, and at 5 minutes and 10 minutes after intubation. Pwd and QT intervals were measured on all ECGs. QTc intervals were determined using the Bazett formula. There was no significant difference in Pwd and QT and QTc intervals on control ECGs. In the sevoflurane group, except for control ECGs, Pwd and QTc interval on all ECGs were significantly longer than those in the propofol group (p < 0.05). We conclude that propofol should be used for anesthesia induction in patients with a predisposition to preoperative arrhythmias, and in those whose Pwd and QTc durations are prolonged on preoperative ECGs.

Drug-induced arrhythmias

The objective of this review is to characterize the mechanisms, risk factors, and offending pharmacotherapeutic agents that may cause drug-induced arrhythmias in critically ill patients. PubMed, other databases, and citation review were used to identify relevant published literature. The authors independently selected studies based on relevance to the topic. Numerous drugs have the potential to cause drug-induced arrhythmias. Drugs commonly administered to critically ill patients are capable of precipitating arrhythmias and include antiarrhythmics, antianginals, antiemetics, gastrointestinal stimulants, antibacterials, narcotics, antipsychotics, inotropes, digoxin, anesthetic agents, bronchodilators, and drugs that cause electrolyte imbalances and bradyarrhythmias. Drug-induced arrhythmias are insidious but prevalent. Critically ill patients frequently experience drug-induced arrhythmias; however, enhanced appreciation for this adverse event has the potential to improve prevention, treatment, patient safety, and outcomes in this patient population.

Effects of propofol or etomidate on QT interval during electroconvulsive therapy

BACKGROUND

Because patients with major depression have an altered autonomic nervous system activity, the risk of arrhythmias and sudden cardiac death may be increased. In addition, electroconvulsive therapy (ECT) may cause an acute rise in QT dispersion, which may predispose to arrhythmias. In this study, we investigated the effects of propofol or etomidate on the corrected QT (QTc) interval during ECT in patients with major depression.

MATERIALS AND METHODS

Fourteen unpremedicated American Society of Anesthesiologists I patients, each scheduled for 6 ECT sessions for major depression, were included in a prospective, randomized crossover study. The patients randomly received either 1-mg/kg propofol (propofol group) or 0.2-mg/kg etomidate (etomidate group). The mean arterial pressure (MAP), heart rate (HR), and electrocardiogram were recorded before anesthetic induction, 0 and 1 minute after the seizure ended, and 3 and 10 minutes after the seizure ended (T3 and T4, respectively).

RESULTS

In the propofol group, the QTc interval was shorter than the baseline at 0 minute after the seizure ended. The QTc interval increased from the baseline at T3 and T4 in the etomidate group. In the etomidate group, the QTc interval was longer at T3 and T4 than that in the propofol group (P < 0.05). In the etomidate group, the HR increased at T3 and T4, but the MAP increased at all measurement times from the baseline value. The HR and the MAP were lower at T3 and T4 in the propofol group than in the etomidate group (P < 0.05).

CONCLUSIONS

Propofol did not induce prolongation of the QT interval and controlled the hemodynamic response better than etomidate during ECT. Therefore, propofol may be more suitable than etomidate for ECT treatments.

[Long QT syndrome and anaesthesia]

The long QT syndrome (LQTS) is a rare, congenital or acquired disease, which may lead to fatal cardiac arrhythmias (torsade de pointes, TdP). In all LQTS subtypes, TdPs are caused by disturbances in cardiac ion channels. Diagnosis is made using clinical, anamnestic and electrocardiographic data. Triggers of TdPs are numerous and should be avoided perioperatively. Sufficient sedation and preoperative correction of electrolyte imbalances are essential. Volatile anaesthetics and antagonists of muscle relaxants should be avoided and high doses of local anaesthetics are not recommended to date. Propofol is safe for anaesthesia induction and maintenance. The acute therapy of TdPs with cardiovascular depression should be performed in accordance with the guidelines for advanced cardiac life support and includes cardioversion/defibrillation and magnesium. Torsades de pointes may be associated with bradycardia or tachycardia resulting in specific therapeutic and prophylactic measures.

Effects of fentanyl pretreatment on the QTc interval during propofol induction

Prolongation of the corrected QT (QTc) interval is associated with various anaesthetic drugs. The QTc prolongation may become more exacerbated during laryngoscopy and intubation, which is possibly caused by sympathetic stimulation. The aim of this study was to investigate the effects of fentanyl on the QTc interval during propofol induction in healthy patients. The patients were randomly allocated to receive either fentanyl (n = 25) or saline (n = 25) before induction. The QTc interval was significantly prolonged immediately after intubation in control group compared to preceding values, but it did not change in the fentanyl group. The number of patients with the prolonged QTc interval exceeding 20 ms immediately after intubation compared to the baseline values was 14 in the control group and seven in the fentanyl group. In conclusion, pretreatment with fentanyl 2 microg x kg(-1) significantly attenuated QTc prolongation associated with laryngoscopy and tracheal intubation during propofol induction.

Targeted deletion of kcne2 impairs ventricular repolarization via disruption of I(K,slow1) and I(to,f)

Mutations in human KCNE2, which encodes the MiRP1 potassium channel ancillary subunit, associate with long QT syndrome (LQTS), a defect in ventricular repolarization. The precise cardiac role of MiRP1 remains controversial, in part, because it has marked functional promiscuity in vitro. Here, we disrupted the murine kcne2 gene to define the role of MiRP1 in murine ventricles. kcne2 disruption prolonged ventricular action potential duration (APD), suggestive of reduced repolarization capacity. Accordingly, kcne2 (-/-) ventricles exhibited a 50% reduction in I(K,slow1), generated by Kv1.5--a previously unknown partner for MiRP1. I(to,f), generated by Kv4 alpha subunits, was also diminished, by approximately 25%. Ventricular MiRP1 protein coimmunoprecipitated with native Kv1.5 and Kv4.2 but not Kv1.4 or Kv4.3. Unexpectedly, kcne2 (-/-) ventricular membrane fractions exhibited 50% less mature Kv1.5 protein than wild type, and disruption of Kv1.5 trafficking to the intercalated discs. Consistent with the reduction in ventricular K(+) currents and prolonged ventricular APD, kcne2 deletion lengthened the QT(c) under sevoflurane anesthesia. Thus, targeted disruption of kcne2 has revealed a novel cardiac partner for MiRP1, a novel role for MiRPs in alpha subunit targeting in vivo, and a role for MiRP1 in murine ventricular repolarization with parallels to that proposed for the human heart.

Electrophysiologic Mechanism Underlying Action Potential Prolongation by Sevoflurane in Rat Ventricular Myocytes

Background:

Despite prolongation of the QTc interval in humans during sevoflurane anesthesia, little is known about the mechanisms that underlie these actions. In rat ventricular myocytes, the effect of sevoflurane on action potential duration and underlying electrophysiologic mechanisms were investigated.

Methods:

The action potential was measured by using a current clamp technique. The transient outward K+ current was recorded during depolarizing steps from −80 mV, followed by brief depolarization to −40 mV and then depolarization up to +60 mV. The voltage dependence of steady state inactivation was determined by using a standard double-pulse protocol. The sustained outward current was obtained by addition of 5 mm 4-aminopyridine. The inward rectifier K+ current was recorded from a holding potential of −40 mV before their membrane potential was changed from −130 to 0 mV. Sevoflurane actions on L-type Ca2+ current were also obtained.

Results:

Sevoflurane prolonged action potential duration, whereas the amplitude and resting membrane potential remained unchanged. The peak transient outward K+ current at +60 mV was reduced by 18 ± 2% (P &lt; 0.05) and 24 ± 2% (P &lt; 0.05) by 0.35 and 0.7 mm sevoflurane, respectively. Sevoflurane had no effect on the sustained outward current. Whereas 0.7 mm sevoflurane did not shift the steady state inactivation curve, it accelerated the current inactivation (P &lt; 0.05). The inward rectifier K+ current at −130 mV was little altered by 0.7 mm sevoflurane. L-type Ca2+ current was reduced by 28 ± 3% (P &lt; 0.05) and 33 ± 1% (P &lt; 0.05) by 0.35 and 0.7 mm sevoflurane, respectively.

Conclusions:

Action potential prolongation by clinically relevant concentrations of sevoflurane is due to the suppression of transient outward K+ current in rat ventricular myocytes.

A Comparison of the Effect on Dispersion of Repolarization of Age-Adjusted MAC Values of Sevoflurane in Children

BACKGROUND

QT interval prolongation is associated with torsades des pointes (TdP), but is a poor predictor of drug torsadogenicity. Susceptibility to TdP arises from increased transmural dispersion of repolarization (TDR) across the myocardial wall, rather than QT interval prolongation per se. TDR can be measured on the electrocardiogram as the time interval between the peak and end of the T-wave (Tp-e). Thus Tp-e is a readily measured assay of drug torsadogenicity. Several anesthetic drugs prolong the QT interval, but their effect on TDR is largely unknown.

METHODS

We investigated the effects of sevoflurane on corrected QT (QTc) and Tp-e intervals in 54 unpremedicated ASA I-II children, aged 3-10 yr, who were randomized to receive sevoflurane 1, 1.25, or 1.5 MAC, age-adjusted. Twelve-lead electrocardiograms were recorded before and after sevoflurane exposure. QTc and Tp-e were compared within and among groups using 2-way analysis of variance. Change in Tp-e after sevoflurane exposure was the primary outcome measure.

RESULTS

Sevoflurane significantly prolonged preoperative QTc at all doses (P < 0.005), with no dose-response relationship, but had no effect on preoperative Tp-e.

CONCLUSION

Sevoflurane markedly prolongs the QTc in healthy children, but does not increase dispersion of repolarization as measured by the Tp-e interval, indicating low or no torsadogenicity, and making it unlikely to increase predisposition to TdP.

Effects of Positioning in Laparoscopic Adnexal Surgery on QT Dispersion and Heart Rate Variability Under Sevoflurane Anesthesia

PURPOSE

This study compared the intraoperative changes in the corrected QT dispersion and heart rate variability, predictors of autonomic cardiac function, in laparotomic and laparoscopic adnexal surgery.

MATERIALS AND METHODS

The study was conducted on 46 American Society of Anaesthesiologists class I/II patients, aged 33-51 years, randomized to one of two groups, for elective gynecologic laparotomy or laparoscopy for a benign adnexal mass. Anesthesia was induced and maintained with sevoflurane. Corrected QT dispersion and spectral powers of heart rate variability were measured at baseline, before the induction of anesthesia, and intraoperatively during the adnexal surgery for 15 minutes. The lithotomy and Trendelenburg positions were set at 145 degrees and 30 degrees between thigh and body, respectively. Pneunoperitoneum was established at 12 mm Hg. Laparoscopic surgery was performed via one principal and two ancillary ports. Data were analyzed using the Wilcoxon and Mann-Whitney tests.

RESULTS

A significant increase was observed in intraoperative standard deviation of RR interval values of heart rate variability in both groups compared to preoperative values (P < 0.05). The corrected QT dispersion and low and high frequency heart rate variability showed no significant changes between the two groups.

CONCLUSION

Gynecologic laparoscopy with pneumoperitoneum in the lithotomy and Trendelenburg positions is as safe as laparatomy and seems not to deteriorate the autonomic cardiac function.

Effects of sevoflurane on QT dispersion and heart rate variability

The purpose of this study was to use estimates of corrected QT dispersion (QTcd) and heart rate variability (HRV) to assess the effects of sevoflurane, an inhalation agent used frequently in clinical practice, on autonomic cardiac function. This study was conducted prospectively and in a blind manner on 20 women between 38 and 51 y of age who were classified as American Society of Anesthesiologists stage I-II and whose treatment required total abdominal hysterectomy. Electrocardiograms were recorded by 12-lead Holter monitor for 5 min before sevoflurane induction and again for 5 min at 10 min after tracheal intubation. Data on the first recording were considered as baseline; those on the second recording were viewed as final data. The study was terminated at this point, and surgery was allowed to proceed. QTcd and HRV values were assessed by a cardiologist, who was blinded to all data. All parameters were expressed as a mean value +/- standard deviation. Wilcoxon's test was used to compare baseline and final data. Statistical significance was considered as P<.05. No significant changes were observed between baseline and final QTcd values and between low- and high-frequency components (LF and HF) of HRV; nor were changes seen in the LF/HF ratio. With the patient under sevoflurane/ nitrous oxide anesthesia, no significant changes were detected in QTcd, LF, and HF values, and in the LF/HF ratio, whereas a significant increase (P=.001) was seen in standard deviation of the R-R interval, which was used as a measure of cardiac autonomic tone.

The Effects of Sevoflurane and Propofol on QT Interval and Heterologously Expressed Human Ether-A-Go-Go Related Gene Currents in Xenopus Oocytes

Sevoflurane can induce prolongation of the cardiac QT interval by inhibiting the repolarization phase of the action potential. This may occur as a result of inhibition of the human ether-a-go-go related gene (HERG) channel. To clarify the mechanisms of anesthetics on HERG channels, we monitored the electrocardiogram and measured QT intervals in the guinea pig in the presence of sevoflurane and propofol. Sevoflurane (1%-4%) prolonged QTc dose-dependently (7.5%-21.2%), but propofol did not affect it. Furthermore, HERG channels were expressed in Xenopus oocytes and outward HERG currents were obtained on step depolarization from a holding potential of -70 mV. Repolarization to -70 mV from positive test potentials resulted in large outward tail currents. Sevoflurane (1%-4%), in a dose-dependent manner, inhibited the HERG outward tail currents (9.7%-26.6%), whereas steady-state currents were inhibited only at large concentrations. The time constant of the converging current was decreased in the presence of sevoflurane, but the inactivation and activation curves were not shifted. Propofol did not affect these currents within the clinically relevant concentration. In conclusion, compared with steady-state currents, sevoflurane was more potent in inhibiting the outward tail currents, suggesting that sevoflurane may modulate the HERG channel kinetics in its inactivated state.

The Influence of desflurane on QTc interval

Volatile anesthetics may prolong the QTc interval and this may result in grave cardiac arrhythmias. We assessed the effect of desflurane on the QTc interval in 40 ASA physical status I or II patients. Volatile anesthetic induction with desflurane was performed, and after obtaining adequate level of anesthesia, QTc interval, heart rate, and noninvasive arterial blood pressure were measured. Prolongation of the QTc interval was observed within the first minute of anesthesia. There were no differences in QTc interval changes between sexes at any time. We conclude that desflurane prolongs the QTc interval, but that there are no differences between genders in sensitivity to this action.

IMPLICATIONS

We assessed the effect of desflurane on QTc interval in patients without cardiac diseases. Prolongation of the interval was evident by the first minute of desflurane anesthesia. There were no differences between female and male patients.

The Effects of Propofol and Sevoflurane on the QT Interval and Transmural Dispersion of Repolarization in Children

Prolongation of the QT interval is associated with torsades de pointes (TdP), especially in children or young adults with long QT syndromes. Susceptibility to TdP arises from increased transmural dispersion of repolarization (TDR) across the myocardial wall. Several anesthetic drugs prolong the QT interval, but their effect on TDR is unknown. TDR can be measured on the electrocardiograph (ECG) as the time interval between the peak and end of the T wave (Tp-e). We investigated the effects of propofol and sevoflurane on the corrected QT (QTc) and Tp-e intervals in 50 unpremedicated ASA physical status I-II children, aged 1-16 yr, who were randomized to receive propofol (group P) or sevoflurane (group S). Twelve-lead ECGs were recorded preoperatively and intraoperatively. Sevoflurane significantly prolonged the preoperative QTc; propofol did not. Neither anesthetic had any significant effect on the preoperative Tp-e. Sevoflurane increases the duration of myocardial repolarization in children to a larger extent than does propofol, but as the dispersion of repolarization appears unaffected, the risk of TdP is likely to be minimal with either anesthetic.

Alterações eletrocardiográficas em cães pré-medicados com levomepromazina e submetidos à anestesia por propofol e sevoflurano

Avaliaram-se as variáveis eletrocardiográficas em cães submetidos à anestesia pelo sevoflurano. Foram empregados 16 cães clinicamente sadios, adultos, machos ou fêmeas, com peso médio de 15±3,5kg. Administrou-se levomepromazina (1,0 mg/kg) seguida pela administração de propofol (5,0 mg/kg), ambos pela via endovenosa. Os animais foram intubados e submetidos à anestesia inalatória com sevoflurano diluído em oxigênio, através de circuito semi-fechado na concentração de 3,5V%. As aferições das freqüências cardíaca e respiratória, oximetria, capnometria, pressões arteriais sistólica, diastólica e média e das variáveis eletrocardiográficas foram realizadas imediatamente antes da administração da levomepromazina, 15 minutos após e imediatamente antes da administração do propofol, após 15 minutos da administração do agente inalatório e consecutivamente a cada 20 minutos. Após administração de levomepromazina, propofol e sevoflurano observou-se decréscimo das pressões arteriais sistólica e média. A levomepromazina ocasionou prolongamento do intervalo QT. O sevoflurano promoveu prolongamento da onda P e aumento de sua amplitude aos 70 e 130 minutos de anestesia, respectivamente, além de prolongamento do intervalo QT. Concluiu-se que a anestesia por sevoflurano, nas condições deste experimento, promoveu prolongamento do intervalo QT, sem no entanto incorrer em arritmias.