Epidemiology and morbidity of regional anesthesia in children: a follow-up one-year prospective survey of the French-Language Society of Paediatric Anaesthesiologists (ADARPEF)

Background: The French‐Language Society of Paediatric Anaesthesiologists (ADARPEF) designed a 1‐year prospective, multicenter and anonymous study to update both epidemiology and morbidity of regional anesthesia in children. Methods: From November 2005 to October 2006, data from participating hospitals were recorded using an identification form, a data recording form, and a complication form. Information collected included the characteristics of the hospitals, the number and type of regional anesthetics (RA), the age of the involved children as well as the incidence, and type of complications. Results: Data collected in 47 institutions included 104 612 pure general anesthesias (GAs), 29 870 GAs associated with regional blocks, and 1262 pure regional blocks. Central blocks accounted for 34% of all RA. Peripheral blocks (66%) were upper or lower limb blocks (29% of peripheral blocks), trunk blocks, and face blocks (71%). In children aged ≤3 years, the percentage of central blocks was similar to the peripheral ones (45% vs 55), while in older children, peripheral blocks were more than four times used than central ones. Complications (41 involving 40 patients) were rare and usually minor. They did not result in any sequelae. The study revealed an overall rate of complication of 0.12%; CI 95% [0.09–0.17], significantly six times higher for central than for peripheral blocks. Conclusions: As a result of the low rate of complications, RA techniques have a good safety profile and can be used to provide postoperative analgesia. In addition, the results should encourage anesthesiologists to continue to use peripheral instead of central (including caudal) blocks as often as possible when appropriate.     

Association Between Nonreentrant Supraventricular Tachycardia and Atrioventricular Node Reentrant Tachycardia: A Presentation of Dual AV Node Physiology

Persistent simultaneous conduction of P waves over a fast and a slow nodal pathway defines the nonreentrant type of supraventricular tachycardia, usually not associated with reciprocating movements. We report a unique association between this uncommon tachycardia and a usual AV nodal reentrant tachycardia, made possible by the existence of three different nodal pathways.     

Differential Effects of Quinidine, Flecainide, and Cibenzoline on Anisotropic Conduction in the Isolated Porcine Heart

Differential Drug Effects on Anisotropic Conduction. Introduction:Anisotropic conduction characteristics, expressed as the ratio of conduction velocities in the longitudinal (V_l) and transverse (V_t) fiber directions, may play a role in the mechanism of some ventricular tachycardias and is influenced by pharmacologic interventions. Discrepancies exist among the reported orientation-dependent effects of available Class I antiarrhythmic drugs. The aim of this study was to assess the respective effects of quinidine (Class IA), flecainide (Class IC), and cibenzoline (not subclassifled) on the anisotropic conduction of porcine hearts, in corroboration of their effects on ventricular action potentials. Methods and Results: We studied the actions of 3 and 10 μM quinidine, 1 and 3 μM flecainide, and 0.3 and 1 μM cibenzoline on V_l and V_t determined from 128 electrograms recorded with a plaque electrode on the anterior left ventricle of isolated perfused hearts (spacing 2.5 mm). V_l and V_t were computed from isochronal maps displaying ellipsoid activation during stimulation from the center of the plaque. The effects on the maximal rate of depolarization (V˙_max) of action potentials were obtained from ventricular muscle exposed to the same drugs. Flecainide [1 μM] and cibenzoline [0.3 μM] did not alter V_l, and V_t, significantly. Quinidine [3 μM] predominantly depressed V_l at rapid pacing rates, hut the V_l/V_t ratio was not significantly altered. Quinidine [10 μM] and flecainlde [3 μM] reduced V_l and V_t in a frequency dependent fashion. Conversely, cibenzoline [1 μM] mostly decreased V_l and thus decreased the V_l/V_t ratio and increased the V_l/V_t at all pacing rates. This different effect was not related to a greater depressant effect on V˙_max. Conclusion: Quinidine and flecainide act similarly on the anisotropic pattern of conduction (both drugs increase the V_l/V_t ratio), whereas cibenzoline exerts opposite effects. Orientation dependent effects are different among Class I antiarrhythmic drugs and may be of importance in their therapeutic efficacy or proarrhythmic potential.     

Reverse Electrical Remodeling by Cardiac Resynchronization Therapy: Prevalence and Clinical Impact

Intrinsic QRS Narrowing with CRT . Background: Cardiac resynchronization therapy (CRT) improves left ventricular ejection fraction (LVEF) in patients with congestive heart failure, LV systolic dysfunction, and a wide QRS complex. Previous reports suggest that CRT may also induce electrical remodeling but the impact on clinical outcome remains unknown. Objective: We sought to determine (1) if chronic CRT induces a relevant shortening of the intrinsic QRS (iQRS), (2) whether changes in the native conduction system correlate with clinical or echocardiographic response to CRT, and (3) to identify predictors of iQRS width shortening. Methods: We prospectively included 85 consecutive patients with left bundle‐branch block who received a CRT device in 3 French centers. NYHA class, iQRS duration, LVEF, and left ventricular volumes were assessed before and 1 year after CRT implantation. Clinical and echocardiographic CRT responders were defined respectively as NYHA class improvement >1 class without heart failure hospitalization and an increase of LVEF by ≥10% and/or a decrease in LVESV by ≥15%. Electrocardiographic responders were defined as a decrease in iQRS duration by ≥20 ms. Results: Baseline and 1‐year follow‐up mean iQRS durations were, respectively, 168.0 ± 19.7 ms and 149.6 ± 31.6 ms (P < 0.0001). Electrocardiographic response, observed in 43/85 patients (51%), was associated with a greater rate of clinical (P = 0.035) and echocardiographic (P = 0.023) response. Younger age, male gender, and longer baseline QRS width were independent predictors of electrocardiographic response. Conclusion: CRT decreases iQRS duration. A reduction of at least 20 ms in iQRS duration is associated with better clinical and echocardiographic response. (J Cardiovasc Electrophysiol, Vol. 23, pp. 1219–1227, November 2012)     

Pacemaker‐Mediated Tachycardia: Manufacturer Specifics and Spectrum of Cases

Pacemaker‐mediated tachycardia (PMT) is the term used to describe a repetitive sequence of sensed retrograde P waves followed by ventricular pacing at or below the maximum tracking rate. The following events can promote atrioventricular (AV) dissociation, retrograde conduction, and the onset of PMT: ventricular or atrial extrasystole, an excessively long programmed AV delay, external interference or myopotentials sensed by the atrial channel, atrial sensing or pacing failure, the absence of postventricular atrial refractory period extension after removal of a magnet, and VDD pacing at a higher rate than sinus rate. In contemporary devices, each manufacturer has a proprietary algorithm to detect and terminate PMT. Because of the increase in the number and complexity of the pacing algorithms and because of manufacturer‐driven differences, a basic understanding of these new algorithms is important for patient care. We review here the main elements of the physiopathology of this type of tachycardia, describe the specific characteristics of the different manufacturers, and present representative clinical cases.     

Discovery of a pituitary adenoma following a gonadotropin-releasing hormone agonist in a patient with prostate cancer

Gonadotropin-releasing hormone (GnRH) agonists have become the treatment of choice for locally advanced and metastatic prostate cancer. We report a case of prostate cancer in which this treatment led to severe symptoms of intracranial hypertension due to the concomitant presence of an asymptomatic functional pituitary adenoma. A 70-year-old white man was initially evaluated for a multifocal adenocarcinoma, Gleason score 6 (3+3) with perineural invasion suggesting an extracapsular extension. A conformational external beam radiation (74 Gy) with a concomitant GnRH agonist (leuprolide) was initiated. Almost 10 days after the administration of leuprolide the patient complained of visual disturbance, diplopia and other symptoms of intracranial hypertension. Magnetic resonance imaging (MRI) of the brain demonstrated a large sella mass lesion. To relieve the patient's symptoms, a transsphenoidal subtotal tumorectomy was necessary. The histopathological examination revealed an invasive gonadotroph pituitary adenoma. Two years later, there is no sign of progression either on his prostatic disease (prostate-specific antigen of 0.21 ng/mL) or on his pituitary disease (FSH, 4.7 UI/L, LH, 3.1 UI/L and total testosterone, 627 ng/dL) with values of the hypothalamic-pituitary axis in the normal range. We advocate that a high index of suspicion of pituitary tumor must be considered in any case of intracranial hypertension following the administration of GnRH agonist. Abarelix could have a place in such cases.     

Can improvements in water supply reduce childhood diarrhoea?

The effects of improving the water supply on the incidence ofdiarrhoea in 1096 children from three neighbouring villagesof the Kirotshe rural health district. Northern Kivu, Zairewere investigated. Two of these villages had piped water, whilethe third village had no such facility. Children aged underfour years on registration were visited fortnightly for oneyear. Median diarrhoea incidence per two weeks proved to besignificantly lower in the two intervention villages than inthe control village. In the two intervention villages, mediandiarrhoea incidence per two weeks was halved in children wholived in households located less than a five-minute walk fromthe public standpipe, or in households using more than 50 litresof water a day. The association between diarrhoea incidenceand facility use did not differ after stratification by socioeconomicvariables. These findings underscore the fact that children in householdsthat use standpipes are exposed to a lower risk of diarrhoea.Therefore, it is important to stress that those in charge ofthe planning and implementation of water supply interventionsinvestigate the access to, and use of, water amongst the targetpopulation.     

Relationship Between Interatrial Conduction Times and Left Atrial Dimension in Patients Undergoing Atrioventricular Stimulation

Interatrial conduction time (IACT) and left atrial dimension (LAD) were determined in 75 patients (41 males, 34 females, mean age 78.2 ± 7,9 years) undergoing atrioventricular (AV) stimulation. The LAD was measured by M mode echocardiography as the distance between the posterior aortic wall and the posterior left atrial wall. The IACT was determined during a transvenous dual chamber pacemaker implant done under local anesthesia (lidocaine). The spontaneous interatrial conduction time (SIACT) was measured from the intrinsic deflection (ID) of the right atrium recorded in a unipolar mode (unipolar J-shaped had positioned in the right appendage) to the ID of the left atrium (bipolar esophageal lead, left atrial positive deflection equal to the negative one) during sinus rhythm. The right atrium then was paced at a rate slightly greater than the spontaneous one. The paced interatrial conduction time (PIACT) was measured from the stimulus artifact to the left atrial ID. The PIACT was also measured during incremental right atrial pacing (10 beats/min step increase to 180 beats/min) and, from these measurements, the maximum increase of PIACT (MIPIACT) was deduced. The LAD was measured at 39.5 ± 8.7 mm, SIACT at 70.3 ± 24.8 msec, PIACT at 118.8 ± 27.9 msec, and MIPIACT at 16.5 ± 16.4 msec. We found highly significant relationships between SIACT and LAD(P = 0.0006, r - 0.39), PIACT and LAD (P = 0.0001, r = 0.45), and MIPIACT and LAD (P = 0.0006, r = 0.38). We also noted that the LAD was greater in patients in whom MIPIACT was >10 msec than in patients in whom the MIPIACT was negligible (P < 0.002). However, the “r” values indicate that IACT is probably determined by multiple factors, and LAD appears to be one of the most important. Thus, we demonstrated the existence of highly significant relationships between the LAD determined by M mode echocardiography and the IACT when sensing and pacing the right atrium. We also demonstrated that the LAD was greater in patients in whom PIACT increased by an appreciable duration during fast atrial pacing. These results must be kept in mind when choosing a mode of stimulation and determining the AV delay (dual chamber pacemaker), particularly in patients with left atrial enlargement in whom the contribution of the atrial contraction and its timing are hemodynamically determinant.