Drug‐induced long QT syndrome and fatal arrhythmias in the intensive care unit

Long QT syndrome (LQTS) is a genetic or acquired condition characterised by a prolonged QT interval on the surface electrocardiogram (ECG) and is associated with a high risk of sudden cardiac death because of polymorph ventricular tachyarrhythmia called Torsade de Pointes arrhythmia. Drug‐induced LQTS can occur as a side effect of commonly used cardiac and non‐cardiac drugs in predisposed patients, often with baseline QT prolongation lengthened by medication and/or electrolyte disturbances. Hospitalised patients often have several risk factors for proarrhythmic response, such as advanced age and structural heart disease. Patients in the intensive care unit (ICU) are particularly prone to develop drug induced LQTS because they receive several different intravenous medications. Additionally, they might have impaired drug elimination because of reduced kidney and/or liver function, and also drug‐drug‐interactions. The clinical symptoms and signs of LQTS range from asymptomatic patients to sudden death because of malignant arrhythmias, and it is therefore important to recognise the clinical characteristics and typical ECG changes. Treatment of acquired LQTS is mainly awareness, identification and discontinuation of QT prolonging drugs, in addition to eventually supplement of magnesium and potassium. Overdrive cardiac pacing is highly effective in preventing recurrences, and antiarrhythmic drugs should be avoided. Recent data suggest that QT prolongation is quite common in ICU patients and adversely affects patient mortality. Thus, high‐risk patients should be sufficiently monitored, and the use of medications known to cause drug‐induced LQTS might have to be restricted.     

Brief review: Anesthetic implications of long QT syndrome in pregnancy

PURPOSE: To review the effects of the long QT syndrome (LQTS) in the parturient and the current anesthetic management of patients with LQTS. SOURCE: Relevant articles were obtained from a MEDLINE search spanning the years 1980-2006 and a PubMed search spanning the years 1949-2006. Bibliographies of retrieved articles were searched for additional articles. PRINCIPAL FINDINGS: The prevalence of LQTS in the developed world is one per 1,100 to 3,000 of the population. Clinically, LQTS is characterized by syncope, cardiac arrest and occasionally, by a history of seizures. The QT interval can also be prolonged by drugs, electrolyte imbalances, toxins and certain medical conditions. Long QT syndrome patients are at risk of torsades de pointes and ventricular fibrillation. Medical management aims to reduce dysrhythmia frequency. The LQTS is subdivided into different groups (LQT1-6) depending on the cardiac ion channel abnormality. Torsades can be precipitated by adrenergic stimuli such as stress or pain (LQT1 and 2), sudden noises (LQT2) or whilst sleeping (LQT3). Patients with LQTS require careful anesthetic management as they are at high risk of torsades perioperatively despite minimal data on the effects of anesthetic agents on the QT interval. While information on effects of LQTS in pregnancy is limited, the incidence of dysrhythmia increases postpartum. Isolated case reports of patients with LQTS women highlight several peripartum dysrhythmias. CONCLUSION: An understanding of LQTS and the associated risk factors contributing to dysrhythmias is important for anesthesthesiologists caring for parturients with LQTS.     

QT间期延长综合征与麻醉

QT间期延长综合征(long QT syndrome,LQTS)是由于离子通道变异,可引起致死性心律失常的一类疾病.围术期是LQTS的高危时期.此文总结了各种麻醉药物对QT间期的影响,以及LQTS患者围术期处理的注意事项,但尚不能确定最合理的麻醉方法,未来的研究应着重于手术期间的生理和药理对跨壁复极离散度的影响.     

Torsade de pointes during sevoflurane anesthesia and fluconazole infusion in a patient with long QT syndrome. A case report

We present the occurrence of 'torsade de pointes' induced by the combination of peroperative fluconazole administration and sevoflurane anesthesia in a patient with 'long QT syndrome' (LQTS) scheduled for resection of a sacral abscess. Eight minutes following uneventful induction of anesthesia 'torsade de pointes' occurred, terminated by a counter shock. At this time the end-tidal concentration of sevoflurane was 2%. The fluconazole infusion was disconnected and the operation was continued. Post-operatively the patient awakened uneventfully. The direct postoperative ECG showed a QTc of 531 ms (preoperative QTc of 442 ms.) and remained prolonged afterwards. A long QT syndrome was the most likely diagnosis. LQTS is classified as either congenital or acquired. Patients with acquired LQTS may have an underlying predisposition for QT prolongation. Many drugs have shown to be associated with a prolonged QT interval (1). The syndrome in this particular patient was unmasked by sevoflurane. Concomitant administration of fluconazole might have further predisposed the patient to the development of 'torsade des pointes'. Although LQTS is relatively rare, it is important for the anesthesiologist to be familiar with the disease because of the associated morbidity and mortality and the potential for anesthesia to induce malignant arrhythmias in asymptomatic carriers.     

Left thoracoscopic sympathectomy and stellate ganglionectomy for treatment of the long QT syndrome

The long QT syndrome (LQTS) is a rare inherited cardiac disorder that may induce fatal cardiac arrhythmias. Patients diagnosed with this disorder generally have several treatment options, including beta-blockade, cardiac pacing, an implantable automatic defibrillator, or a high thoracic left sympathectomy. We report the case of a 6-year-old girl with the LQTS treated by left thoracoscopic sympathectomy and stellate ganglionectomy. The procedure was performed after an initial thorascopic attempt at another institution failed due to inadequate resection of the sympathetic chain. Operative time was 85 min and blood loss was minimal. There were no intraoperative or postoperative complications. The girl's QT interval decreased and she was discharged on the 4th postoperative day. After 9 months of follow-up, she remains asymptomatic. We conclude that the LQTS patients who fail medical treatment can be treated successfully with left thoracoscopic cervicothoracic sympathectomy. We recommend that the extent of sympathectomy for treating the LQTS be T1-T4 and either the entire stellate ganglion or at least the inferior one-third.     

Spinal anesthesia for Cesarean section in a parturient with long QT syndrome

PURPOSE: To report the first use of spinal anesthesia for Cesarean section (CS) in a parturient with a long QT syndrome (LQTS) and an automatic implantable cardiac defibrillator (AICD). Although both general and epidural anesthesia have been described for CS in patients with LQTS, there are no previous case reports on the use of spinal anesthesia. The clinical features, diagnosis, treatment and anesthetic management of LQTS are discussed. CLINICAL FEATURES: A 31-yr-old woman, gravida 2 para 1 known to have LQTS and an AICD, presented in labour at 35 weeks gestation, three weeks before her scheduled CS. Her previous delivery by CS under spinal anesthesia at our institution was uneventful. On this occasion, we elected to administer spinal anesthesia because she was asymptomatic (no arrhythmia or cardiac arrest) for the last few years, was hemodynamically stable, and had received uneventful spinal anesthesia before. CONCLUSION: Spinal anesthesia was used safely for CS in this parturient with LQTS.     

The treatment of the long QT syndrome

General principles of long QT syndrome (LQTS) management are presented first. The management of pause-dependent LQTS includes the following steps: A. recognition of torsades de pointes type of ventricular tachycardia and of the ecg warning signs, B. termination of the arrhythmia and the ecg warning signs by interventions which do not shorten the QT interval and by interventions which also shorten the QT interval. The management of adrenergic-dependent LQTS includes the following steps: A. individual risk stratification, B. avoidance of deleterious sympathetic stress, C. recognition of the arrhythmia and of the ecg warning signs, D. termination of the arrhythmia, E. prevention of relapses using beta-blockers, high left cervico-thoracic sympathectomy, permanent pacemakers and automatic implantable cardioverter-defibrillators.     

Anesthesia for videoscopic left cardiac sympathetic denervation in children with congenital long QT syndrome and catecholaminergic polymorphic ventricular tachycardia – a case series

Objective: To describe our experience in the anesthetic management of pediatric patients who have undergone left cardiac sympathetic denervation (LCSD) for congenital long QT syndrome (LQTS) and catecholaminergic polymorphic ventricular tachycardia (CPVT). Background: Long QT syndrome and CPVT predispose patients to ventricular arrhythmias and sudden death. One treatment option for these patients is LCSD. When these patients present for LCSD or other surgical procedures, anesthetic management is challenging, as many medications may exacerbate QT prolongation. Methods: Retrospective review of the electronic medical records of 22 pediatric patients who underwent LCSD between November 2005 and December 2008. Results: Six patients (27%) received midazolam as a premedication. Eleven patients (50%) underwent inhalation induction with sevoflurane. Eighty‐six percentage received either sevoflurane or isoflurane for maintenance of anesthesia, while the remaining 14% received a propofol infusion. Nine patients (41%) received esmolol infusions intraoperatively, while one patient (4.5%) received a labetalol infusion. Three patients (14%) received lidocaine infusions. No significant cardiac or other events occurred in any of these patients in the perioperative period. Conclusions: Important anesthetic considerations in this population include avoidance of sympathetic stimulation, correction of any abnormal electrolytes, and the immediate availability of a defibrillator and magnesium sulfate to treat arrhythmias. Anxious patients may benefit from premedication to reduce sympathetic tone. We have safely used both volatile agents and propofol for induction and maintenance of anesthesia. In our experience, intraoperative infusions of β‐blockers and lidocaine seem to be helpful in reducing arrhythmogenic potential, especially in patients with profound QT prolongation.     

Perioperative management of long QT syndrome in a child with congenital heart disease

During cardiac catheterization, a 2(1/2)-year-old boy developed sudden cardiac arrest. The presence of a long QT interval in the electrocardiogram (ECG) along with ventricular arrhythmia and syncope at that moment enabled us to diagnose long QT syndrome (LQTS). Immediate defibrillation and beta-blocker (metoprolol) therapy saved the life of the child. Cardiac catheterization was completed and the child was planned for Fontan operation. Beta-blocker coverage, prevention of sympathetic stimulation and avoidance of agents which prolong the QT interval made anesthesia uneventful. There were episodes of ventricular fibrillation (VF) in the postoperative period. The child was managed with electrical defibrillation, metoprolol and magnesium.     

Manifestation of Long QT syndrome with normal QTc interval under anesthesia: a case report

Patients with congenital Long QT are known to have normal QT interval in symptom-free period and in the early years of life. Precipitating factors like surgical stress, interactions with anesthetic agents prolonging QT interval, and electrolyte imbalances can manifest with life threatening arrhythmias in congenital or acquired Long QT syndrome. We report a case of concealed LQTS manifesting under anesthesia and its subsequent perioperative course.     

Long QT interval syndrome with increased QT dispersion

This case report describes the anaesthetic management of a patient with sporadic-type long QT interval syndrome (LQTS), and increased QT dispersion, who presented for removal of an ovarian cyst. Beta adrenergic blockade and adequate depth of anaesthesia for successful management is emphasized. The Successful use of epidural administration of lignocaine and opioids in addition to general anaesthesia is described.     

Total intravenous anesthesia for repositioning an implantable defibrillator in a patient with long QT syndrome

We report the case of a 27-year-old woman with congenital long QT syndrome (LQTS) who was scheduled for surgery to reposition an implantable defibrillator. Given the risk of sudden death due to fatal ventricular arrhythmia, the woman required implantation of a defibrillator with pacemaker capability. Combined anesthesia-analgesia was used in order to minimize the risk of ventricular arrhythmia caused by increased serum concentrations of catecholamines. When cardioversion, defibrillation and anti-tachycardia functions had been deactivated, anesthesia was induced with propofol, fentanyl and rocuronium. Anesthesia was maintained with an infusion of propofol and remifentanil. We describe the pathophysiology and treatment of LQTS and discuss anesthetic management for repositioning a defibrillator in a patient with congenital LQTS.     

The effect of two different protocols of potassium haemodiafiltration on QT dispersion.

BACKGROUND: The risk of developing cardiovascular diseases is higher in patients on haemodialysis than in the general population. These patients may develop arrhythmias that depend on the extra- and intracellular concentrations of potassium. ECG findings, particularly the QT interval and its dispersion (QT(d)) and the QT(c) (QT interval corrected for heart rate according to Bazett's formula) and its dispersion (QT(cd)), may be direct indicators of the risk of developing arrhythmia. METHODS: Our cohort comprised 28 patients who were dialysed for 3.5-4 h three times per week, first with haemodiafiltration with a constant potassium concentration (HDF) in the dialysis bath then with haemodiafiltration with variable concentrations of potassium (HDF(k)). ECGs were done at different time intervals: at the start of dialysis (T(0)), at 15 (T(15)), 45 (T(45)), 90 (T(90)) and 120 min (T(120)) after the beginning of the session, and at the end of treatment (T(end)). ECG-derived data (QT, QT(d), QT(c) and QT(cd)) were measured. At the same time points, plasma electrolytes, intra-erythrocytic potassium and the electrical membrane potential at rest (REMP) of the erythrocytic membrane were measured. RESULTS: Plasma potassium concentration diminished more gradually in HDF(k) than in HDF, the difference being statistically significant at T(15) and T(45) (P<0.05), and T(90) (P<0.01). The intra-erythrocytic potassium concentration remained constant throughout the observation period. In both HDF and HDF(k), REMP was lower at all points after T(0) (P<0.05), but the reduction was greater and more significant in HDF than in HDF(k) at T(15) and T(120) (P<0.05). ECG revealed a statistically significant diminution in HDF(k) vs HDF in the measures of dispersion of QT and QT(c) at T(15), T(90), T(120) and T(end) (P<0.01) and of QT(cd) at T(45) (P<0.05). The mean of QT(d), adjusted for plasma potassium, increased over time in HDF with large alternate mean increase and decrease peaks and error intervals. In HDF(k), instead, there was a progressive and constant diminution with minor error intervals. QT(cd) adjusted for plasma potassium had the same trend. A marked difference was found between the final values in standard HDF and those in HDF(k). CONCLUSIONS: HDF and HDF(k) have significantly different effects on QT(c). ECG data demonstrate that the risk of arrhythmia could be lower, with a variable removal of potassium during haemodialysis. With HDF but not HDF(k), hyperpolarization of the cell membrane is detected, and this could have a destabilizing effect on different types of cardiac cell, giving rise to retrograde circuits.     

Cardiac Arrest During Laparoscopic Roux-en-Y Gastric Bypass in a Bariatric Patient with Drug-Associated Long QT Syndrome

Obese patients often may demonstrate an acquired prolonged QTc interval due to alteration in cardiac physiology, electrolyte disturbances, and/or medication use. Intraoperatively, bariatric surgery may further contribute additional cardiac stressors to obese patients with long QT syndrome (LQTS). We present a case report of an obese woman with LQTS who underwent laparoscopic Roux-en-Y gastric bypass surgery and sustained an intraoperative cardiac arrest. We discuss identification, prevention, and treatment strategies for LQTS in the bariatric surgery patient.     

Electrocardiographic changes during and after isoflurane-induced hypotension for neurovascular surgery

We evaluated the effects of isoflurane anaesthesia and induced hypotension in 33 neurosurgical patients by electrocardiographic monitoring and serial cardiac enzyme measurements. An electrocardiogram (ECG) and serum enzymes were obtained preoperatively, intraoperatively and postoperatively in the recovery room and for three consecutive days. ECG leads II, V1 and V5 were monitored continuously during anaesthesia. Patients who had had a subarachnoid haemorrhage and a high incidence of abnormal preoperative ECG (42 per cent). Ten patients developed ECG changes intraoperatively, but these changes were unrelated to isoflurane-induced hypotension. Fifty-three per cent of patients developed an abnormal postoperative ECG. These abnormalities consisted mostly of nonspecific ST segment or T wave changes. At no time was there an elevation in cardiac enzyme activity. We found that nonspecific ECG changes are relatively common in patients undergoing vascular neurosurgical procedures. There was no enzymatic evidence of myocardial infarction and we can only speculate that these ECG changes are related to intracranial surgical manipulation.     

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.     

Laparoscopic surgery: does it increase the probability of atrial and ventricular arrhythmias in children?

PURPOSE: Despite the minor physiologic changes those occur during laparoscopic procedures, pneumoperitoneum with CO2 insufflation may induce alterations in electrocardiographic (ECG) variables, which may predict severe atrial and ventricular arrhythmias. This study aims to assess QT dispersion (QTD) and P wave dispersion (PWD) changes in children who have undergone laparoscopic appendectomy. PATIENTS AND METHODS: Sixteen patients (12 males and 4 females) who had preoperative diagnosis of appendicitis were included in the study. As laparoscopic exploration revealed appendicitis in all patients, laparoscopic appendectomy was performed. Preinsufflation (ECG1), postinsufflation (ECG2), predesufflation (ECG3), and postdesufflation (ECG4) ECGs were achieved at a speed of 25 mm/s for QTD and PWD analyses. RESULTS: Although mean corrected QTD and PWD at ECG2 and ECG3 were significantly greater than ECG1 and ECG4, those changes induced by insufflation of CO2 were reversible. CONCLUSIONS: The clinical significance of pneumoperitoneum, which causes an increase in corrected QTD and PWD in children, remains to be determined with further studies.     

Acquired long QT syndrome and elective anesthesia in children

We present the case of a child who had had a previous episode of torsades de pointes (TdP) and who was scheduled for elective surgery under general anesthesia. The pathophysiology of this condition and the anesthesia concerns are discussed. An 8-year-old male with a history of osteogenic sarcoma had undergone an uneventful limb salvage procedure 2 years earlier. During a subsequent admission to the hospital, he had had a cardiopulmonary arrest with complete recovery. Telemetry electrocardiogram (ECG) rhythm recordings obtained during the event showed TdP that degenerated into ventricular fibrillation, which then terminated spontaneously. On a subsequent ECG, the QTc interval was 694 ms. The prolonged QT interval was attributed to homeopathic use of cesium chloride supplements and the QT interval normalized after cesium was stopped. He presented for an elective procedure and, with an anesthetic plan that emphasized medications without known effect on the QT interval, had an uneventful perioperative course. The optimal anesthesia plan for patients with prolonged QT or those suspected to be at risk for prolongation of the QT interval has not been well described. Available evidence suggests that using total intravenous anesthesia with propofol may be the safest and was used uneventfully in this case. Additionally, this case emphasizes the need to inquire about the use of supplements and naturopathic medications, even in children, that may have life-threatening side effects or interactions with anesthetic agents.     

Ventricular fibrillation related to reversal of the neuromuscular blockade in a patient with long QT syndrome

The long QT syndrome (LQTS) is associated with syncopal attacks or even sudden death at a young age due to ventricular fibrillation. We report a patient with an undiagnosed LQTS who had an episode of cardiac arrest during the final part of general anesthesia, immediately after the drugs for reversal of the neuromuscular blockade were given. We suggest that the administration of glycopyrronium might have been the provoking factor in this patient.     

Effects of sevoflurane versus propofol on QT interval.

BACKGROUND: Prolongation of the QT interval is an alteration of the electrocardiogram (ECG) that may result in a potentially dangerous polymorphic ventricular tachycardia known as torsade de pointes. Michaloudis et al. investigated the effect of isoflurane and halothane on the QT interval in premedicated and non premedicated children, and in premedicated adults. Isoflurane significantly prolonged the QTc interval, in contrast to halothane, which shortened the QTc interval. The aim of the study was to evaluate the effect of sevoflurane on the QT interval in patients undergoing non-cardiac surgery. METHODS: One hundred and eighty patients classified as ASA physical status I-III were enrolled and 102 were excluded. Patients had been scheduled for elective non cardiac surgery. Exclusions criteria were: cardiovascular impairment or chronic obstructive lung disease, medication affecting QT interval, and an abnormal prolongation of the QTc interval (440 ms). The patients were then randomly allocated to one of two groups, one receiving sevoflurane anesthesia and the other receiving propofol anesthesia. In all patients, a 12 lead ECG was recorded before surgery, after intubation, after extubation. The investigators reading the ECG were blinded to the type of induction and anesthesia used. The following variables were recorded or calculated: heart rate, P-R interval, QRS interval, QT interval, QTc interval according to Bazett's formula, systolic, diastolic and mean blood pressure. RESULTS: The sevoflurane significantly prolongs the QT and the QTc interval, whereas the induction and total intravenous anesthesia with propofol significantly shortens the QT but not the QTc interval. CONCLUSIONS: The amount the sevoflurane-associated QT prolongation may possibly be of clinical significance in some patients presenting long QT syndrome, hypokalemia, or in presence of other agents or factors that lengthen QT.