Alfentanil-midazolam anaesthesia has no electrophysiological effects upon the normal conduction system or accessory pathways in patients with Wolff-Parkinson-White syndrome

Remimazolam Tolerance in Long-term Benzodiazepine Users: A Case Report of 2 Cases

A 60-year-old woman with a 5-year history of anxiolytic use, a diazepam-equivalent daily dose of 15 mg, was scheduled for esophageal stent removal. She was given remimazolam (0.5 mg/kg) but remained fully alert. She only lost consciousness with propofol (40 mg). A 61-year-old man with a 1-year history of anxiolytic use, diazepam-equivalent daily dose of 20 mg, was scheduled for hand tumor resection. He was given remimazolam (0.3 mg/kg) but remained fully alert. He only lost consciousness after desflurane inhalation. In a patient with a history of long-term benzodiazepine use, anesthetic or sedative agents aside from remimazolam should be considered.

Perioperative management of patients with pre-excitation syndromes

Patients with pre-excitation abnormalities are at a high risk for life-threatening perioperative arrhythmias. In Wolff-Parkinson-White syndrome, the anaesthetics used for invasive diagnostic testing/ablation, should not affect cardiac electrophysiology; propofol, sevoflurane, fentanyl, sufentanil, alfentanil are suitable. In non-ablative surgery, propofol, sevoflurane, isoflurane, fentanyl, alfentanil, sufentanil have been used safely. Among neuromuscular blockers, cis-atracurium, rocuronium and vecuronium are good choices. Ketamine, pancuronium and pethidine should be avoided because of their sympathomimetic actions. Anticholinergic/ anticholinesterase combinations for neuromuscular block reversal should preferably be omitted, while sugammadex seems more attractive. In regional anaesthesia, addition of epinephrine and high sympathetic blocks should be avoided. Hypotension should be treated with pure alpha-adrenergic agonists. Other pre-excitation abnormalities associated with different accessory pathways are the Mahaim Fiber and Lown-Ganong-Levine syndrome. Sympathetic activation should be avoided. Total intravenous anaesthesia with propofol probably represents the safest option. A careful anaesthetic plan and close cooperation with cardiologists are mandatory for successful management.

Total intravenous anesthesia with target-controlled infusion of remifentanil and propofol for ablation of atrial fibrillation

BACKGROUND AND OBJECTIVES

Although ablation of atrial fibrillation (AF) is common in other centers, among us it is a new procedure. The choice of anesthesia, monitors, and anesthesiologic care for this procedure performed outside the surgical center has not been described. The objective of this report was to describe an anesthesia technique for ablation of AF.

CASE REPORT

This is a 49-year old female weighing 73 kg, 155 cm, and ASA II due to hypertension. The patient was monitored with a 12-lead ECG, pulse oximetry, heart rate, bispectral electroencephalography for BIS measurement, suppression rate (SR), and SEF95, and mean arterial pressure (MAP). Intravenous target-controlled infusion (TCI) of propofol with a target of 4 microg x mL(-1), intravenous TCI of remifentanil with a target of 3 ng x mL(-1), and intravenous bolus of rocuronium 0.2 mg x kg(-1) were used for induction of anesthesia. The pharmacokinetic model of propofol described by Marsh was used and incorporated into the propofol PFS pump. The pharmacokinetic model of remifentanil described by Minto was incorporated into the Alaris PK infusion pump. Local effector, or biophase, concentrations corresponded to the information obtained from the infusion pumps and represented predictive measurements of the concentrations of both drugs on their sites of action. The concentrations of propofol and remifentanil were regulated according to BIS and MAP, respectively.

CONCLUSIONS

Total intravenous anesthesia for ablation of AF can be a safe option considering the lack of electrophysiological changes in accessory pathways. The literature on this subject is scarce and new publications could justify, or not, this type of anesthesia during ablation of AF.

[Electrophysiological effects of sevoflurane in comparison with propofol in children with Wolff-Parkinson-White syndrome]

OBJECTIVE

To evaluate the electrophysiological effects of sevoflurane in children with Wolff-Parkinson-White (WPW) syndrome undergoing radiofrequency ablation.

METHODS

We performed a prospective study of 15 patients with WPW syndrome who were scheduled for an electrophysiological study (EPS) and radiofrequency ablation. Anesthesia was induced with fentanyl (2 microg/kg), propofol (3 mg/kg), and vecuronium (0.1 mg/kg), and initially maintained using propofol (100 microg/kg), with bolus administration of fentanyl and vecuronium as required. Four intracardiac catheters were introduced for the EPSpropofol, which included measurements of sinus-node function, sinoatrial-node conduction, refractory periods (atrial, AV-node, accessory pathway anterograde and retrograde, and ventricular), and the characteristics of induced orthodromic tachycardia. The propofol was then replaced with sevoflurane (1 MAC adjusted for age) and the measurements were repeated (EPSsevoflurane). The EPSpropofol and EPSsevoflurane data were compared using the Wilcoxon signed-rank test.

RESULTS

The mean (SD) age was 9.3 (6) years. After administration of sevoflurane, the duration of the antegrade effective refractory period of the accessory pathway increased (EPSpropofol, 283 (22) ms; EPSsevoflurane, 298 (25) ms; P = .004), as did the duration of the minimum pacing cycle with 1:1 atrioventricular conduction (EPSpropofol, 244 (41) ms; EPSsevoflurane, 273 (28) ms; P = .028). No significant changes were observed in the other parameters. Ablation of the accessory pathway was achieved in all patients.

CONCLUSIONS

Sevoflurane partially modified the properties of the accessory pathway but did not prevent ablation.

Effects of ventricular premature stimulus coupling interval on blood pressure and heart rate turbulence

BACKGROUND

Heart rate turbulence (HRT) is a promising noninvasive risk stratifier for mortality after myocardial infarction. On the basis of a study of ventricular premature complex coupling interval and sympathetic nerve burst amplitude, we hypothesized that measures of HRT would increase with increased prematurity of the coupling interval.

METHODS AND RESULTS

Twenty-eight patients undergoing programmed electrical stimulation were studied (12 with prior myocardial infarction, aged 60+/-18 years). An extrastimulus was delivered from the right ventricular apex after 20 sinus beats with a V-S(2) coupling interval decremented by 20 to 30 ms until refractoriness was reached. Turbulence slope (TS), turbulence timing (TT), and turbulence onset were calculated for each extrastimulus, and the linear regressions of these parameters on coupling interval and compensatory pause were calculated. Arterial blood pressure was measured with arterial catheter or a noninvasive continuous blood pressure transducer (Buffington cuff). TS and turbulence onset were abnormal in 4 and 13 patients, respectively. HRT parameters were significantly correlated with coupling interval or compensatory pause in only 2 or 3 patients for a given regression analysis. This absence of correlation was found likely to be due to lack of correlation between compensatory pause and systolic blood pressure after the compensatory pause. Heart rate and TS were correlated: Patients with high heart rate had low TS and late TT (TS=-2.7+0.01xsinus cycle length, P=0.018; TT=8.8 to 0.005xsinus cycle length, P=0.013).

CONCLUSIONS

HRT can be induced by programmed stimulation. In this setting, heart rate affects HRT but not ventricular premature complex prematurity. Induced HRT seems to be a valid method for measuring HRT parameters in patients with few ventricular premature complexes.

Pediatric Anesthesia for Cardiac Catheterization and Electrophysiology Studies

In recent years interventional procedures have been intro duced to the field of pediatric catheterization. These proce dures continue to develop and be applied to patients with reduced cardiovascular reserve as an alternative to cardiac surgery or when cardiac surgery with cardiopulmonary by pass is contraindicated. More frequently anesthesiologists are being called on to provide support in sedating, anesthe tizing, or resuscitating these patients. As more compli cated procedures are performed, the anesthetist plays a pivotal role in the management of the patient to prevent mortality and major morbidity in the cardiac catheterization laboratory.

Effects of isoflurane on electrophysiological measurements in children with the Wolff-Parkinson-White syndrome

This study was designed to assess the effects of isoflurane (ISO) on the electrophysiological properties of the accessory pathway, atrium, ventricle, and AV node in children with the Wolff-Parkinson-White (WPW) syndrome. The results of programmed electrical stimulation were analyzed in 51 patients (4 months to 17 years of age) with WPW. The study population was divided into two groups. Twenty-seven patients received local anesthesia and intramuscular injection of meperidine, promethazine, and chlorpromazine (MPC group). Twenty-four patients received general anesthesia with ISO inhalation (ISO group). We compared the antegrade effective refractory period of the accessory pathway (antegrade APERP), ventricular effective refractory period (VERP), atrial effective refractory period (AERP), AH interval, and cycle length of circus movement tachycardia (CMT-CL) in 12 pairs of age and sex matched patients selected from the MPC and ISO groups. Of the 12 pairs of age and sex matched patients, antegrade APERP in patients who received ISO (299 +/- 17 ms, mean +/- SEM) was significantly longer as compared with matched patients in the MPC group (262 +/- 5 ms, P < 0.025). The VERP and AERP in patients from the ISO group were significantly prolonged compared with the MPC patients (239 +/- 7 vs 210 +/- 8 ms, P < 0.025, and 228 +/- 11 vs 180 +/- 6 ms, P < 0.01, respectively). There was no significant difference in the AH interval or CMT-CL between the two subgroups. Thus, ISO prolongs the antegrade APERPs as well as the effective refractory periods of atrial and ventricular muscle in children with WPW, while the AH interval and CMT-CL appear to be unaffected. Care must be taken in interpreting measurements of the antegrade APERP made in patients under general anesthesia for RF ablation of accessory pathways.

Paediatric cardiac catheterization: innovations

In recent years interventional procedures have been introduced to the field of paediatric cardiac catheterization. These procedures continue to develop in complexity and increasingly are being applied to patients with reduced cardiovascular reserve, as an alternative to cardiac surgery or when cardiac surgery with cardiopulmonary bypass is contraindicated. More frequently anaesthetists are being called upon to provide support in sedating, anaesthetizing or/and resuscitating these patients. The purpose of this review is to give a comprehensive update of the interventional procedures and to review the anaesthetic management techniques as they apply to the catheterization laboratory. We will discuss possible complications and management strategies from our own experience and the experience of others. We have observed that as more complicated procedures are performed the anaesthetist plays a pivotal role in the management of the patient from arrival to departure from the cardiac catheterization laboratory, and in preventing mortality and major morbidity. Although the economic consequences of interventional cardiological techniques remain unclear, the field continues to expand and more complex procedures are continually being introduced.