The safety of modern anesthesia for children with long QT syndrome

Prediction of anesthetic torsadogenicity using a human ventricular cell model

This simulation study was designed to predict the torsadogenicity of sevoflurane and propofol in healthy control, as well as type 1 and type 2 long QT syndrome (LQT1 and LQT2, respectively), using the O'Hara-Rudy dynamic model. LQT1 and LQT2 models were simulated by decreasing the conductances of slowly and rapidly activating delayed rectifier K+ currents (IKs and IKr, respectively) by 50%, respectively. Action potential duration at 50% repolarization level (APD50) and diastolic intracellular Ca2+ concentration were measured in epicardial cell during administration of sevoflurane (1 ~ 5%) and propofol (1 ~ 10 μM). Torsadogenicity can be predicted from the relationship between APD50 and diastolic intracellular Ca2+ concentration, which is classified by the decision boundary. Whereas the relationships in control and LQT1 models were distributed on nontorsadogenic side in the presence of sevoflurane at all tested concentrations, those in LQT2 models were shifted to torsadogenic side by concentrations of ≥ 2%. In all three models, propofol shifted the relationships in a direction away from the decision boundary on nontorsadogenic side. Our findings suggest that sevoflurane, but not propofol, exerts torsadogenicity in patients with reduced IKr, such as LQT2 patients. Caution should be paid to the occurrence of arrhythmia during sevoflurane anesthesia in patients with reduced IKr.

Anesthetic Considerations for Cesarean Delivery in a Parturient With Severe Gitelman Syndrome

Gitelman syndrome is an autosomal recessive inherited disorder that impairs the function of thiazide-sensitive sodium-chloride cotransporters in the distal convoluted tubule of the nephron. During labor and delivery, avoidance of sympathetic overactivity, meticulous hemodynamic monitoring, and expedited repletion of potassium and magnesium are required to avoid adverse outcomes. We present a parturient with severe Gitelman syndrome, requiring continuous electrolyte and fluid infusions, who underwent successful cesarean delivery. Potential severe morbidity was avoided with multidisciplinary planning and management.

Anesthesia for a Child with Congenital Long QT Syndrome, a Case Report and Literature Review

Long QT syndrome is an inherited disorder of the heart's electrical activity that may also be associated with malignant arrhythmia and cause sudden death. In addition to this inherited condition, several commonly used anesthetic drugs can prolong the QT interval. We present here a 17-month-old male patient who underwent general anesthesia for a cochlear implant. No cardiac arrhythmia was observed in the patient, whose muscle relaxant effect was reversed using sugammadex. The application of intravenous anesthetics was preferred to maintain anesthesia for this patient and was safely applied.

Elevation of propofol sensitivity of cardiac IKs channel by KCNE1 polymorphism D85N

BACKGROUND AND PURPOSE

The slowly activating delayed rectifier K⁺ channel (I_Ks ), composed of pore-forming KCNQ1 α-subunits and ancillary KCNE1 β-subunits, regulates ventricular repolarization in human heart. Propofol, at clinically used concentrations, modestly inhibits the intact (wild-type) I_Ks channels and is therefore unlikely to appreciably prolong QT interval in ECG during anaesthesia. However, little information is available concerning the inhibitory effect of propofol on I_Ks channel associated with its gene variants implicated in QT prolongation. The KCNE1 single nucleotide polymorphism leading to D85N is associated with drug-induced QT prolongation and therefore regarded as a clinically important genetic variant. This study examined whether KCNE1-D85N affects the sensitivity of I_Ks to inhibition by propofol.

EXPERIMENTAL APPROACH

Whole-cell patch-clamp and immunostaining experiments were conducted in HEK293 cells and/or mouse cardiomyocyte-derived HL-1 cells, transfected with wild-type KCNQ1, wild-type or variant KCNE1 cDNAs.

KEY RESULTS

Propofol inhibited KCNQ1/KCNE1-D85N current more potently than KCNQ1/KCNE1 current in HEK293 cells and HL-1 cells. Immunostaining experiments in HEK293 cells revealed that pretreatment with propofol (10 μM) did not appreciably affect cell membrane expression of KCNQ1 and KCNE1 proteins in KCNQ1/KCNE1 and KCNQ1/KCNE1-D85N channels.

CONCLUSION AND IMPLICATIONS

The KCNE1 polymorphism D85N significantly elevates the sensitivity of I_Ks to inhibition by propofol. This study detects a functionally important role of KCNE1-D85N polymorphism in conferring genetic susceptibility to propofol-induced QT prolongation and further suggests the possibility that the inhibitory action of anaesthetics on ionic currents becomes exaggerated in patients carrying variants in genes encoding ion channels.

Recurrent syncope in a child and video assisted thoracoscopic surgery - The long and short of it

Long QT syndrome (LQTS) is a myocardial repolarisation disorder caused by cardiac ion channelopathy and one of its common presentations is recurrent syncope. This reduced repolarisation reserve in LQTS can be unmasked by perioperative factors like electrolyte imbalance, drugs, hypothermia and changes in cardiac autonomic tone. We report the anaesthetic management of left thoracoscopic sympathectomy in a 5-year-old child with LQTS and epicardial pacemaker in situ. It is very challenging to isolate the lung on one hand and prevent the predisposition to torsadogenic potential on the other.

Cochlear implantation in children with congenital long QT syndrome: Introduction of an evidence-based pathway of care

Congenital long QT syndrome (cLQTS) is an inherited cardiac ion channelopathy characterized by a long corrected-QT interval on the ECG, associated with a risk of syncope and sudden death as a result of arrhythmias. The archetypal arrhythmia associated with cLQTS is torsade de pointes which may degenerate into ventricular fibrillation. Children with Jervell and Lange-Neilsen syndrome have the combination of cLQTS and congenital sensorineural deafness and may present for cochlear implantation (CI). Sympathetic stimulation and administration of QT-prolonging medications may trigger arrhythmias in children with cLQTS and thus the perioperative period is a time of increased risk of adverse events, with deaths reported in the CI literature. Our Paediatric Cochlear Implant Programme had previously elected to discontinue offering CI to children with cLQTS following a perioperative death. However, subsequent demand for this service by parents led us to develop and introduce a multidisciplinary, evidence-based pathway of care. This pathway modifies the perioperative management of these children to reduce the associated risk. We present the cases of four children with cLQTS who underwent CI in our specialist children's hospital.

Sevoflurane prolonged the QTc interval and increased transmural dispersion of repolarization in a patient with long QT syndrome 3: a case report

We report that sevoflurane not only caused marked QTc interval prolongation but also increased transmural dispersion of repolarization in a patient with long QT syndrome 3 (LQT3). A 16-year-old male with LQT3 underwent a shoulder operation. He experienced no episode of syncope or cardiac arrest, but his preoperative electrocardiography (ECG) showed marked QTc interval prolongation (631 ms) and Tp-e interval prolongation (126 ms). Anesthesia was induced with propofol and maintained with 2% sevoflurane and remifentanil. Although no lethal arrhythmias occurred in the perioperative period, not only the QTc interval but also Tp-e interval was further prolonged by sevoflurane. While sevoflurane has been recognized as a safe anesthetic in terms of QT interval prolongation, even in patients with long QT syndromes, we believe that sevoflurane might be avoided for poorly controlled LQT3 patients.

Anaesthesia for the paediatric outpatient

PURPOSE OF REVIEW

The aim of this review was to discuss recent developments in paediatric anaesthesia, which are particularly relevant to the practitioner involved in paediatric outpatient anaesthesia.

RECENT FINDINGS

The use of a pharmacological premedication is still a matter of debate. Several publications are focussing on nasal dexmedetomidine; however, its exact place has not yet been defined. Both inhalational and intravenous anaesthesia techniques still have their advocates; for diagnostic imaging, however, propofol is emerging as the agent of choice. The disappearance of codeine has left a breach for an oral opioid and has probably worsened postoperative analgesia following tonsillectomy. In recent years, a large body of evidence for the prevention of postoperative agitation has appeared. Alpha-2-agonists as well as the transition to propofol play an important role. There is now some consensus that for reasons of practicability prophylactic antiemetics should be administered to all and not only to selected high-risk patients.

SUMMARY

Perfect organization of the whole process is a prerequisite for successful paediatric outpatient anaesthesia. In addition, the skilled practitioner is able to provide a smooth anaesthetic, minimizing complications, and, finally, he has a clear concept for avoiding postoperative pain, agitation and vomiting.

[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 Year in Review

Congenital cardiac anesthesiology is a rapidly expanding field at both ends of the life spectrum. The care of the unborn child with congenital heart disease is becoming highly specialized in regional centers that offer advanced imaging techniques, coordinated specialist care, and potentially fetal interventions. As more children with congenital heart disease survive to adulthood, patients and their health care providers are facing new challenges. The growing volume of publications reflects this expanding field of congenital cardiac anesthesiology. This year in review article highlights some developing trends in the literature.