The effects of volatile anesthetics on the Q-Tc interval

Propofol prevents further prolongation of QT interval during liver transplantation

Here, we aimed to compare the effects of two anesthetic methods (desflurane inhalation anesthesia vs. propofol-based total intravenous anesthesia (TIVA)] on corrected QT interval (QTc) values during living donor liver transplantation. Altogether, 120 patients who underwent living donor liver transplantation were randomized to either the desflurane or TIVA group. The primary outcome was intraoperative QTc change. Other electrocardiogram, hemodynamic findings and postoperative outcomes were examined as secondary outcomes. QTc values were prolonged intraoperatively in both groups; however, the change was smaller in the TIVA group than in the desflurane group (P_{Group × Time} < 0.001). More patients had QTc values of > 500 ms in the desflurane group than in the TIVA group (63.3% vs. 28.3%, P < 0.001). In patients with preoperative QTc prolongation, QTc was further prolonged in the desflurane group, but not in the TIVA group (P_{Group × Time} < 0.001). Intraoperative norepinephrine and vasopressin use were higher in the desflurane group than in the TIVA group. Propofol-based TIVA may reduce QTc prolongation during living donor liver transplantation compared to that observed with desflurane inhalational anesthesia, particularly in patients with preoperative QTc prolongation. Additionally, patients managed with propofol-based TIVA required less vasopressor during the procedure as compared with those managed with desflurane inhalational anesthesia.

Brugada Syndrome: anesthetic considerations and management algorithm

Brugada Syndrome is characterized by arrhythmogenic risk that may be exacerbated by different metabolic and pharmacological factors. Since its first description, knowledge of this syndrome and its detection by physicians belonging to different specialties have gradually increased. The risk of arrhythmias is well known to increase in the postoperative period, and this risk is particularly accentuated in patients with Brugada Syndrome. The purpose of this review is to analyze the relationship between this syndrome and anesthesia; establish recommendations for the safe management of these patients in the surgical setting; and update the relevant concepts regarding the safety of drug administration in individuals with Brugada Syndrome.

Anesthetic and Perioperative Management of Patients With Brugada Syndrome

Brugada syndrome (BrS) is an arrhythmogenic disease reported to be one among the leading causes of cardiac death in subjects under the age of 40 years. In these patients, episodes of lethal arrhythmias may be induced by several factors or situations, and for this reason, management during anesthesia and surgery must provide some precautions and drugs restrictions. To date, it is difficult to formulate guidelines for anesthetic management of patients with BrS because of the absence of prospective studies, and there is not a definite recommendation for neither general nor regional anesthesia, and there are no large studies in merit. For this reason, in the anesthesia management of patients with BrS, the decision of using each drug must be made after careful consideration and always in controlled conditions, avoiding other factors that are known to have the potential to induce arrhythmias and with a close cooperation between anesthetists and cardiologists, which is essential before and after surgery. In conclusion, given the absence of large studies in literature, we want to focus on some general rules, which resulted from case series and clinical practice, to be followed during the perioperative and anesthetic management of patients with BrS.

Brugada syndrome and its relevance in the perioperative period

Brugada syndrome is an autosomal dominant genetic disorder associated with an increased risk of sudden cardiac death, as well as ventricular tachyarrhythmias. The defective cardiac sodium channels result in usual electrocardiographic findings of a coved-type ST elevation in precordial leads V1 to V3. The majority of patients have uncomplicated courses with anesthesia, surgery, and invasive procedures. However there is risk of worsening ST elevation and ventricular arrhythmias due to perioperative medications, surgical insult, electrolyte abnormalities, fever, autonomic nervous system tone, as well as other perturbations. Given the increasing numbers of patients with inherited conduction disorders presenting for non-cardiac surgery that are at risk of sudden cardiac death, safe anesthetic management depends upon a detailed knowledge of these conditions.

Establishing in vitro to clinical correlations in the evaluation of cardiovascular safety pharmacology

Preclinical studies are vital in establishing the efficacy and safety of a new chemical entity (NCE) in humans. To deliver meaningful information, experiments have to be well defined and provide outcome that is relevant and translatable to humans. This review briefly surveys the various preclinical experiments that are frequently conducted to assess drug effects on cardiac conductivity in early drug development. We examine the different approaches used to establish correlations between non-clinical and clinical settings and discuss their value in the evaluation of cardiovascular risk.

General anaesthesia for insertion of an automated implantable cardioverter defibrillator in a child with Brugada and autism

A 14-year-old autistic boy presented with acute gastroenteritis and hypotension. The electrocardiogram showed a ventricular fibrillation rhythm – he went into cardiorespiratory arrest and was immediately resuscitated. On investigation, the electrocardiogram showed a partial right bundle branch block with a “coved” pattern of ST elevation in leads v₁–v₃. A provisional diagnosis of Brugada syndrome was made, for which an automated implantable cardioverter defibrillator (AICD) implantation was advised. Although the automated implantable cardioverter defibrillator implantation is usually performed under sedation, because this was an autistic child, he needed general anaesthesia. We performed the procedure uneventfully under general anaesthesia and he was discharged after a short hospital stay.

Brugada Syndrome – A Review of the Implications for the Anaesthetist

Brugada syndrome is characterised by specific electrocardiogram changes in the right precordial leads, a structurally normal heart and susceptibility to ventricular arrhythmias that may cause syncope or sudden death in otherwise fit young adults. Perioperative pharmacological and physiological changes may precipitate these events. Arrhythmias and symptoms typically occur at rest or sleep when vagal activity predominates. Although the condition is rare, the implications are serious and may result in death. Individual case reports describe diverse anaesthetic management. In this paper we critically appraise the literature to identify unifying features and determine whether specific management can be recommended. We found 18 clinical reports of anaesthesia including a total of 28 patients, most under general anaesthesia. Those with an implanted defibrillator should have it deactivated. All patients should have external defibrillator pads applied continuously throughout the perioperative period. Electrolyte imbalances should be corrected preoperatively. Propofol infusions for maintenance of general anaesthesia are probably safe if duration and dose are limited. Sevoflurane may be the preferred volatile anaesthetic. Autonomic changes, inadequate analgesia, light anaesthesia and postural changes should be all be minimised. The patient should be warmed or cooled to maintain normothermia. An isoprenaline infusion is advocated for intraoperative ST changes. Regional anaesthesia is possible if the dose is limited and systemic absorption restricted. Lignocaine is the drug of choice while bupivacaine is relatively contraindicated. Ropivacaine is possibly also not safe. Prolonged regional anaesthesia may therefore require continuous catheter techniques. Five-lead electrocardiogram monitoring and ST trend analysis should continue into the postoperative period.

Comparison of the effect of sevoflurane and desflurane on postoperative arrhythmia and QT dispersion

The aim of this study was to investigate the effect of sevoflurane and desflurane on cardiac arrhythmias in adult patients who will be anesthetized. A total of 40 patients who were in the ASA I–II group and who were to undergo elective surgery were included in the study. No pre-medication was administered to the patients. They were monitored with the Holter equipment at preoperative 24 hours, and also at postoperative 24 hours on condition that Holter monitoring will begin before induction. Following routine monitoring, the patients were randomly divided into two equal groups; group one was given sevoflurane and group two was given desflurane. In this study, desflurane and sevoflurane resulted in both a significant prolongation of QT and QTc and a significant increase in QT and QTc dispersion when compared with the basal values. In the sevoflurane group, there was no significant increase in postoperative ventricular arrhythmia, compared to that during the preoperative period. However, this increase was significant in the desflurane group (p = 0.009). Sevoflurane and desflurane result in an increase in QT dispersion. Postoperative rhythmic control should carefully be monitored, especially in the desflurane group.

[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.

Perioperative Management of a 7-Year-Old Child With Brugada Syndrome

Brugada syndrome results from abnormalities in the myocardial transmembrane conduction of sodium, resulting in the characteristic electrocardiographic changes of ST segment elevation in the precordial leads and incomplete right bundle branch block in an otherwise structurally normal heart. Affected patients are frequently asymptomatic until their presentation with potentially lethal arrhythmias including ventricular fibrillation. The youngest reported patient with Brugada syndrome to undergo anesthetic management is presented in this article; the pathophysiology of the syndrome is reviewed, and its perioperative implications are discussed.

Transgenic upregulation of IK1 in the mouse heart is proarrhythmic

The role of the cardiac current Ik1 in arrhythmogenesis remains highly controversal. To gain further insights into the mechanisms of IK1 involvement in cardiac excitability, we studied the susceptibility of transgenic mice with altered IK1 to arrhythmia during various pharmacological and physiological challenges. Arrhythmogenesis was studied in transgenic mice expressing either dominant negative Kir2.1-AAA or wild type Kir2.1 subunits in the heart, models of IK1 suppression (AAA-TG) and up-regulation (WT-TG), respectively. Under normal conditions, both anesthetized wild type (WT) and AAA-TG mice did not display any spontaneous arrhythmias. In contrast,WT-TG mice displayed numerous arrhythmias of various types. In isolated hearts, the threshold concentration for halothane-induced ventricular tachycardias (VT) was increased to 167% [corrected] in the AAA-TG and decreased to 54% [corrected] in WT-TG hearts when compared to WT hearts. The number of PVCs induced by AV node ablation combined with hypokalemia was reduced in AAA-TG hearts and increased in WT-TG mice. After AV node ablation AAA-TG hearts were more tolerant, and WT-TG less tolerant to isoproterenol- induced arrhythmias than WT hearts. Analysis of monophasic action potentials in isolated hearts shows a significant reduction in the dispersion of action potential repolarization in mice with suppressed IK1. The data strongly support the hypothesis that in the mouse heart upregulation of IK1 is proarrhythmic, and that under certain conditions IK1 blockade in cardiac myocytes may be a potentially useful antiarrhythmic strategy.

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 Surgical Patient with Brugada Syndrome: A Four-Case Clinical Experience

Brugada syndrome is characterized by a distinctive electrocardiographic pattern (right bundle branch block and ST segment elevation in precordial leads) and a high risk of cardiac arrest for malignant dysrhythmia. The genetic basis is a molecular defect of the cardiac sodium channel and the pattern of inheritance is autosomal dominant. Many factors during general anesthesia (medications, bradycardia, temperature changes) could precipitate malignant dysrhythmia in these patients. Because criteria to identify the surgical patient at high risk for developing malignant dysrhythmia are lacking, we can only speculate about the available studies on nonsurgical patients. We describe four patients during general anesthesia and propose intraoperative and postoperative monitoring (the first 36 h).

Clinical relevance and management of drug-related QT interval prolongation

Much attention recently has focused on drugs that prolong the QT interval, potentially leading to fatal cardiac dysrhythmias (e.g., torsade de pointes). We provide a detailed review of the published evidence that supports or does not support an association between drugs and their risk of QT prolongation. The mechanism of drug-induced QT prolongation is reviewed briefly, followed by an extensive evaluation of drugs associated with QT prolongation, torsade de pointes, or both. Drugs associated with QT prolongation are identified as having definite, probable, or proposed associations. The role of the clinician in the prevention and management of QT prolongation, drug-drug interactions that may occur with agents known to affect the QT interval, and the impact of this adverse effect on the regulatory process are addressed.

Toxicologic myocardial sensitization

Drug-induced polymorphic ventricular tachycardia (torsades de pointes) may lead to syncope or sudden cardiac death. One mechanism by which drugs and toxins may predispose to the development of this malignant dysrhythmia is through their ability to produce myocardial sensitization. The concept of myocardial sensitization actually represents a series of events involving altered cellular repolarization produced by blockade of myocardial potassium channels. Altered potassium ion flow raises the likelihood that an ectopic beat will occur via an early afterdepolarization and simultaneously alters the myocardial tissue to make it favorable for reentrant dysrhythmias, such as torsades de pointes, to propagate. Alternatively, calcium overload of the myocyte produces ectopy by causing delayed afterdepolarizations, which if the substrate for reentry is present, will result in ventricular tachycardia. This paper discusses the mechanisms underlying the production of both the altered myocardial substrate and the afterdepolarizations.

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.

Inhibitory effects of volatile anesthetics on currents produced on heterologous expression of KvLQT1 and minK in Xenopus oocytes

The slowly activating component of delayed rectifier K+ current (IKs) in the heart modulates the repolarization of cardiac action potential. We investigated the effects of the volatile anesthetics isoflurane and sevoflurane on cloned IKs coexpressed by KvLQT1 and minK. Currents were induced following injection into oocytes of KvLQT1 mRNA (10 ng) with or without minK mRNA (1 ng), which were transcribed in vitro from cDNAs of normal rats hearts. A two-electrode voltage-clamp recording technique was used to investigate the effects of isoflurane (0-1.5 minimum alveolar concentration, MAC) and sevoflurane (0-1.5 MAC) on IKs (KvLQT1 with minK) and KvLQT1 alone currents. Currents were activated by step depolarizations to a series of potentials from a holding potential of -80 mV and measured as the deactivating tail current on repolarization to -60 mV. Following a 2-s depolarization to 40 mV, isoflurane and sevoflurane caused potency-dependent reductions in IKs and KvLQT1 currents. Both of the volatile anesthetics tested accelerated the deactivation of IKs and KvLQT1 currents. We conclude that the significant inhibitory effect of volatile anesthetics on the cloned IKs may partly contribute to the clinical observations of the prolongation of the ventricular repolarization (Q-T interval) by the anesthetics.