Haemodialysis increases QT(c) interval but not QT(c) dispersion in ESRD patients without manifest cardiac disease.

BACKGROUND: HD has been reported to determine an increase in QTc interval and QTc dispersion (QT(max)-QT(min))-risk factors that predispose to severe ventricular arrhythmias and sudden death. However, most studies have included end-stage renal disease (ESRD) patients with significant heart pathology. We therefore aimed to study the impact of a single HD session in subjects without manifest cardiac disease. METHODS: Sixty-eight stable, non-diabetic HD patients (47.1% males, age 40.2+/-12.7 years, HD duration 57+/-36 months and 37% hypertensive), with normal maximal ECG stress test and sub-endocardiac viability index and without ECG left ventricular hypertrophy were included. QT interval was calculated 10 min pre- and post-HD, as an average of three consecutive complexes, and corrected for heart rate using Bazett's formula (QTc=QT/(R-R)(1/2)). Na(+), K(+), Ca(2+), PO(4), pH and BP levels were also determined pre- and post-HD. RESULTS: The QTc interval increased significantly post-HD to 434+/-29 from 421+/-26 ms pre-HD (P=0.005); an abnormally prolonged QTc (>440 ms) was recorded in 34% cases pre-HD and in 46% post-HD, i.e. 1.5-2.3 times higher than in the high risk EURODIAB IDDM population. However, this effect was not homogeneous. Only 47 subjects had an increase in QTc duration after a dialysis session, while in 21 a decrease in QTc duration was recorded. The increase in QTc post-HD correlated with Ca(2+) homeostasis. Patients with greater increases in QTc after dialysis had higher baseline plasma calcium levels (r=0.47, P<0.001); also, a larger decrease in Ca(2+) post-HD correlated with higher increases in QTc interval (r=0.33, P<0.05). In contrast with QTc behaviour and with data from the literature, in this young HD population without manifest cardiac disease and with a low prevalence of HTA, post-HD QTc dispersion was similar to pre-HD values, increasing in only 39 patients. Furthermore, changes in QTc dispersion were not related to changes in electrolytes and BP following dialysis. However, changes in QTc dispersion and in QTc interval were directly correlated (r=0.37, P=0.42). There were no relationships between pre-HD measured echocardiographic variables, including: LV ejection fraction, internal diameters, wall thickness, mass and mass index and baseline or changes in QTc or QTc-d. CONCLUSIONS: Haemodialysis increases the QTc interval in ESRD patients, mainly related to rapid changes in electrolyte plasma concentrations. However, the impact on QTc dispersion is less important in the absence of significant coexisting cardiac disease.     

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 syndrome: anaesthetic management at delivery

We describe the anaesthetic management of a spontaneous vaginal delivery at 39 weeks' gestation in a 22-year-old patient with congenital long QT syndrome. With a strong family history of sudden deaths, the patient had an initial QT interval corrected for rate (QTc) of >600 ms. Following a once-daily 50-mg dose of atenolol over the previous 11 months, her QTc remained prolonged at 560 ms. To minimise any increase in catecholamine levels and consequent risk of malignant ventricular arrhythmias, a combined spinal-epidural technique was selected using intrathecal diamorphine and levobupivacaine, with intravenous and oral magnesium and potassium supplementation. Levobupivacaine was substituted for routine racemic bupivacaine to decrease the risk of drug-induced cardiotoxicity. Delivery outcome was successful and uneventful. We outline the pathophysiology, risks and treatments of long QT syndrome, and discuss the analgesic management of this patient in labour with congenital long QT syndrome.     

Carbon monoxide poisoning - a cause of increased QT dispersion

BACKGROUND: Carbon monoxide (CO) poisoning is associated with direct cardiovascular toxicity. QT dispersion (QTd) of the ECG is an indirect measure of heterogeneity of ventricular repolarization, which may contribute to ventricular arrhythmias. Our aim was to study QTd in patients with acute CO poisoning. METHODS: CO intoxication was confirmed by arterial blood gas analysis. A control group consisted of age- and sex-matched individuals admitted to the hospital for unrelated clinical conditions. 12-lead ECG's were recorded on admission and repeated 1 week after discharge from the hospital. QT dispersion was defined as the difference between the greatest and the least QT intervals in any of the 12 leads. RESULTS: Seventeen intoxicated patients, aged 5-46 years, had mean carboxyhemoglobin levels of 22.5 +/- 11.1%. On admission, corrected QT intervals of the intoxicated patients were significantly increased compared to the control group (431 +/- 18 ms vs. 404 +/- 28 ms, P = 0.008), but not the QT interval (358 +/- 25 ms vs. 345 +/- 20 ms, P = 0.17). Mean QTd and cQTd values (46 +/- 15 ms and 62 +/- 13 ms) of the intoxicated patients were significantly increased compared to the control group (17 +/- 4 ms and 33 +/- 15 ms, P < 0.0001 for both). Both QTd and cQTd decreased significantly after discharge from the hospital (P = 0.0001). CONCLUSION: Although QT dispersion increased in patients with CO poisoning, none of ECG's showed ventricular arrhythmia. Increased QTd in the absence of QT interval prolongation may have a lowered arrhythmogenic potential of CO poisoning.     

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.     

常用麻醉药物对QT间期的影响

背景 迄今为止,临床资料显示有近30多种药物会对QT间期(QT interval,QTc)产生影响,其中包括某些麻醉药物.目的 了解各种常用麻醉药物对QTc的不同影响,有助于临床合理选择麻醉用药.内容 常用的麻醉药及麻醉辅助用药对QTc的不同影响.趋向 通过了解常用麻醉药物对QTc的不同影响,有助于麻醉医师针对不同患者选择合适的麻醉药物,从而有效预防一些可能发生的不良症状.     

Long QT syndrome and anaesthesia

Br J Anaesth 2003; 90: 349–66     

Perioperative management of patients with congenital or acquired disorders of the QT interval

QT prolongation can be attributable to various causes that can be categorised as acquired or congenital. Arrhythmias related to QT prolongation can result in clinical presentations, such as syncope and sudden cardiac death. The perioperative period presents a number of issues that may affect a patient's risk of developing polymorphic ventricular tachycardia or torsades de pointes. Although most patients may have an unremarkable perioperative course, some may have complications; this review article aims to help clinicians avoid potential complications, and to help them address treatment for perioperative issues that may occur.     

Effects of halothane and sevoflurane on QT dispersion in paediatric patients

BACKGROUND: The QT dispersion (QTd) of the ECG is an indirect measure of heterogeneity of ventricular repolarization which may contribute to complex ventricular arrhythmias. We compared the effects of halothane and sevoflurane on QTd, and heart-rate corrected QT dispersion (QTcd). METHODS: Fifty ASA physical status I patients, aged 5-15 years, undergoing general anaesthesia were studied. A control ECG recording was printed before induction of anaesthesia. In the halothane group, anaesthesia was induced with halothane 4% in 2 : 1 ratio of air : O2 mixture and in the sevoflurane group with sevoflurane 8% in 2 : 1 ratio of air : O2 mixture. The ECG was recorded 1 and 3 min after induction of anaesthesia, 1 and 3 min after the administration of vecuronium 0.08 m.kg(-1) intravenous and 1 and 3 min after the tracheal intubation. All ECGs were analysed by two cardiologists blinded to the anaesthetic. RESULTS: Although QTd increased in both groups following intubation, this difference was not statistically significant when compared with control values. Following intubation five patients in the halothane group had ventricular arrhythmias of short duration, whereas no arrhythmias were recorded in the sevoflurane group (P = 0.052). Following intubation, QTd (45 +/- 15 ms vs 40 +/- 14 ms) and QTcd (60 +/- 17 ms vs 55 +/- 16 ms) values in the halothane group were significantly greater than the sevoflurane group (P < 0.05). CONCLUSION: Neither sevoflurane nor halothane caused a significant increase in QTd compared with control values before induction. Only QTd following intubation was significantly greater in the halothane group than the sevoflurane group.     

QT interval dispersion in dialysis patients

The leading cause of mortality in dialysis patients is cardiovascular complications, including ventricular arrhythmias and sudden cardiac death. A reliable non-invasive predictive test of sudden death is therefore important. The interlead variation in duration of the QT interval on the surface electrocardiogram corrected with heart rate (QTc dispersion) might serve as a surrogate for ventricular arrhythmia. Prolonged QTc dispersion is commonly encountered in dialysis patients and possesses an increased risk of all mortality, including cardiovascular mortality. QT dispersion might be affected by shifts of the intracellular electrolytes during dialysis and increasing deposition of iron in cardiac muscles in these patients who have underlying heart diseases. Although no well-designed study has been done, the factors contributing to prolongation of QTc dispersion should be avoided. We summarize the results of the currently available clinical studies that examined QTc dispersion in dialysis patients.     

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.     

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.     

Reversible increase in QT dispersion during carbon monoxide poisoning

Increased QT dispersion is a marker for cardiac morbidity and mortality. Carbon monoxide (CO) is a potent myocardial toxin and this report describes the change in QT dispersion during intensive care therapy for severe CO poisoning.     

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.     

Torsade de pointes during sevoflurane anesthesia in a child with congenital long QT syndrome

We present a case of congenital long QT syndrome which developed torsade de pointes during sevoflurane anesthesia for implantation of an internal cardioverter-defibrillator. The diagnosis, implications and treatment are discussed.     

围术期急性心肌梗死患者心电图Q-T离散度改变与猝死的关系

目的　了解围术期急性心肌梗死患者心电图 Q- T离散度 ( Q- Td)改变与猝死的关系。方法　分析 10年间围术期急性心肌梗死患者 3 3例及 3 5例同期心电图正常组的 Q - Td、J- Td及 Q-Tcd的变化。结果　围术期急性心肌梗死组的 Q- Td、J- Td及 Q- Tcd分别是 63 .4± 2 0 .7,5 8.4± 19.5和 ( 68.4± 2 0 .9) m s,均显著高于对照组 ( P<0 .0 1)。并发于心肌梗死猝死组 Q- Td显著高于心肌梗死存活组 ( P<0 .0 1)。结论　心电图 Q- Td对判断围术期急性心肌梗死患者病情程度有重要参考价值。     

QT intervals and QT dispersion in patients with subarachnoid hemorrhage

Purpose. To clarify the clinical significance of QT dispersion and the longest QT intervals (L-QTc) in patients with subarachnoid hemorrhage (SAH). Methods. ECGs, clinical features, and laboratory data were analyzed in 38 patients with SAH (R) and 30 with unruptured cerebral aneurysms (U). Standard 12-lead ECGs obtained on admission were analyzed manually, and the longest QT interval (L-QTc) and the QT dispersion (difference between longest and shortest QTc) were compared between groups. Results. There were no differences between groups R and U in age, sex, or location of aneurysms. The QT dispersion and L-QTc were greater in R than in U (109 ± 49 vs 64 ± 21 ms and 503 ± 63 vs 435 ± 38 ms, respectively; P < 0.01). The QT dispersion and L-QTc were longer in patients with premature ventricular contractions (PVCs) than in patients without PVCs (185 ± 30 vs 85 ± 41 ms and 586 ± 47 vs 467 ± 59 ms, respectively; P < 0.01). There were positive correlations between QT dispersion or L-QTc and preoperative Hunt and Hess grade (rs = 0.560 and rs = 0.615, respectively; P < 0.01). QT dispersion and L-QTc tended to correlate negatively with serum K⁺ (r = −0.365 and r = −0.376, respectively). Conclusion. QT dispersion in patients with SAH is prolonged, especially in high-grade cases. Received: July 19, 2000 / Accepted: November 9, 2000     

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.