Atrial Refractory Periods after Atrial Premature Beats in Patients with Paroxysmal Atrial Fibrillation

To study the effects of an atrial premature beat on atrial refractory periods, we investigated 11 patients (group A) who were the control group, 12 patients suffering from paroxysmal atrial fibrillation (group B), and 10 patients (group C) without arrhythmias but with cardiopathy or cardiomyopathy. At every eighth complex of a constant atrial electrostimulated rhythm a fixed premature extrastimulus was introduced, and effective and functional refractory periods (ERP and FRP) were measured in three different sites of the right atrium, before and after introduction of this extrastimulus. Average ERP and FRP shortened respectively in group A, from 220.28 ± 25.68 msec and 281.17 ± 28.15 msec before extrastimulation, to 190.58 ± 22.74 msec and 245.88 ± 19.86 msec after; in group B, from 219.44 ± 27.38 msec and 284 ± 30.06 msec to 191.66 ± 28.72 msec and 253.23 ± 34.01 msec; and in group C from 229.03 ± 29.65 msec and 289.67 ± 51.62 msec to 194.19 ± 24.6 msec and 237.74 ± 39.59 msec. The average dispersions of ERP and FRP in group A were, respectively: 41.81 ± 21.36 msec and 36.36 ± 18.04 msec before extrastimulation, 28.18 ± 18.14 msec and 35.45 ± 15.72 msec after. In group B: 26.66 ± 19.46 msec and 41.66 ± 16.96 msec versus 45.83 ± 23.91 msec and 45 ± 34.77 msec and in group C: 27 ±11.59 msec and 45 ± 29.15 msec versus 29 ± 18.52 and 27 ± 18.88. It is concluded that an atrial premature beat tends to shorten the dispersion of atrial refractory periods when patients are free of arrhythmias, and to lengthen them when paroxysmal atrial fibrillation are documented.     

Diaphragm Pacing with a Quadripolar Phrenic Nerve Electrode: An International Study

We sought to determine the international experience with the quadripolar diaphragm pacer system and to test two hypotheses: the incidence of pacer complications would be (1) increased among pediatric as compared to adult patients; and (2) highest among active pediatric patients with idiopathic congenital central hypoventilation syndrome (CCHS). Data were collected via a questionnaire coupled with the Atrotech Registry data for a total of 64 patients (35 children and 29 adults) from 14 countries. Thoracic implantation of electrodes and bilateral pacer use each occurred in 94% of all subjects. Tetraplegic (vs pediatric CCHS) patients were more typically paced 24 hours/day (P = 0.001). Pacing duration averaged 2.0 ± 1.0 years among children and 2.2 ± 1.1 years among adults. Infections occurred among 2.9% of surgical procedures, all in pediatric CCHS patients (vs pediatric tetraplegic patients, P = 0.01). The incidence of mechanical trauma was 3.8%, without significant differences among patient groups. The incidence of presumed electrode and receiver failure were 3.1% and 5.9%, respectively, with internal component failure greater among pediatric CCHS than pediatric tetraplegic patients (P < 0.01). Intermittent or absent function of 0–4 electrode combinations occurred among 19% of all patients, with increased frequency among pediatric CCHS than pediatric tetraplegic patients (P < 0.03). Complication- free successful pacing occurred in 60% of pediatric and 52% of adult patients. In all, 94 % of the pediatric and 86% of the adult patients paced successfully after the necessary intervention. Although pacer complications were not increased among pediatric as compared to adult patients, the incidence of complications was highest among the active pediatric patients with CCHS. Longitudinal study of these patients will provide invaluable information for modification and improvement of the quadripolar system.     

Long-Term Follow-Up After Right Atrial Radiofrequency Catheter Treatment of Paroxysmal Atrial Fibrillation

Catheter ablation of paroxysmal atrial fibrillation using long linear lesions in the right atrium is still under investigation, and its long-term follow-up is unknown. Methods: Thirty-six men and nine women (aged 51 ± 12 years) with symptomatic daily episodes of AF for 6 ± 5 years despite the use of 4.7 ± 1.5 antiarrhythmic drugs were studied between July 1994 and January 1996. Progressively longer ablation lines were performed in 3 groups of 15 consecutive patients each, using a 14-electrode catheter or a single-electrode dragging technique. Success was defined as atrial fibrillation elimination or recurrence for no longer than 6 hours over 3 months of observation. Patients who had fewer than 6 hours of atrial fibrillation per month were considered "improved." Medium- (11 ± 4 months) and long-term (26 ± 5 months) results were assessed clinically from a patient's diary and from Holter recordings. Results: After a follow-up of 11 months, 24 patients had a favorable result of the ablation procedure with or without additional antiarrhythmic drug therapy, representing 53% of the original cohort. After 26 ± 5 months of follow-up, these successful results were reduced to 17 patients (37%). Conclusions: After linear atrial ablation, a significant long-term attrition of arrhythmia-free patients was observed. This may be due to a combination of disease progression, incomplete linear block, and ineffective ablation of arrhythmogenic triggers.     

Incidence and Prevention of Cardiac Tamponade Complicating Ablation for Atrial Fibrillation

Cardiac tamponade complicating catheter ablation of atrial fibrillation (AF) occurs in approximately 1% of pulmonary vein isolation (PVI), and up to 6% of linear ablation procedures. We reviewed 348 consecutive AF ablation (including repeat) procedures over 1 year, which all included PVI, with additional linear lesions at the mitral isthmus in 73%, and cavotricuspid isthmus (CTI) in 76%. An irrigated-tip ablation catheter was used, with power limited to 25–35 W for PVI and 45–60 W for linear lesions. Tamponade occurred in seven men and three women (2.9% of the population) during the creation of linear ablation lesions. Mechanical perforations occurred in two patients, and "popping" during radiofrequency (RF) energy delivery at the mitral isthmus in six, and at the CTI in two patients. Peak RF power was significantly higher in patients with than without tamponade (53 ± 4 W vs 48 ± 7 W; P = 0.02), and was greater than 48 W in all cases of "popping." In the following year, RF power for linear ablation was limited to ≤42 W. Among 398 procedures, tamponade occurred in four patients (1.0%; P = 0.047 vs first year), three from "popping" and one from mechanical trauma. Procedural success rate remained the same despite reduction of power. Risk of tamponade was highest during linear ablation, mainly associated with high energy delivery and "popping." Reducing the energy limited, though did not eliminate this complication.     

Malignant Ventricular Tachycardia During Propafenone Treatment in a Child with Junctional Automatic Tachycardia: Effectiveness of Intravenous Molar Sodium Lactate

Propafenone may aggravate the preexisting arrhythmia or induce another one. Usually, such proarrhythmic effects occur in patients with spontaneous ventricular arrhythmias and/or coronary heart disease with poor left ventricular function. We report the case of a 5-year-old girl with Junctional automatic tachycardia and no structural heart disease, in whom malignant ventricular tachycardia occurring during propafenone treatment could be terminated by molar sodium lactate (MSL) infusion. The serum propafenone level obtained before MSL infusion was within the therapeutic range. Two hypothesis could explain the beneficial effects of MSL in our patient: (1) alkalinization facilitates the cell membrane hyperpolarization and thus can decrease the voltage-dependent effect of Class Ic drugs, (2) alkalinization could displace propafenone from its tissue receptor sites by an increase in the nonionized fraction.     

Pregnancy and prosthetic heart valves: a French cooperative retrospective study of 155 cases

A French cooperative retrospective study analysed 155 pregnanciesin 103 women with prosthetic heart valves: 95 mechanical prosthesis(MP) and 60 bioprostheses (BP). Among them 13 MP and 10 BP werebivalvular and four were mixed implants. In all, 182 (108 MPand 74 BP) prostheses were exposed to the risk of pregnancy.Among the 108 MP-bearing patients, 16 thromboembolic accidents(TEA) were recorded: 10 thromboses in 13 mitral, two aorticand one pulmonary MP. TEA were four times more frequent underoral anticoagulant therapy. Among the 74 BP, seven sufferedpremature valve failure. Ninety-nine infants were born to 50MP-bearing women (53%) and 48 BP-bearing patients (80%) (P<0.001).Twenty miscarriages were reported; they occurred more oftenunder anticoagulant treatment (17%) than without it (4%) P<0.02).Coumarin-induced embryopathies were rare (only one definitivelyidentified). Because pregnancy with an MP under anticoagulanttherapy is dangerous for the mother and may effect the fetus,the therapeutic indications for women of child-bearing age mustbe taken into consideration. In a women already with an MP atthe time of conception, the duration of heparin therapy shouldbe limited to the following two periods: from the 6th to the12th week (coumarin-induced embryopathies) and during the last2 weeks of gestation (haemorrhages during delivery and the neonatalperiod).     

Performance of a Radiation Protection Cabin During Implantation of Pacemakers or Cardioverter Defibrillators

Radioprotection for Cardiac Device Implant . Introduction: Pacemaker implants are associated with a high cumulative exposure of the operators to radiation. Standard radiation protection with lead aprons is incomplete and the cause of spine disorders. A radiation protection cabin offers complete protection by surrounding the operator, without requiring a lead apron. Methods: We randomly and evenly assigned 60 patients undergoing implantations of permanent pacemakers or cardioverter defibrillators (ICD) with (a) a radiation protection cabin (cabin group, n = 30) versus (b) standard protection with a 0.5 mm lead‐equivalent apron (control group, n = 30). Radiation exposure was measured using personal electronic dosimeters placed on the thorax, back, and head of the operator. Results: The patient, procedural, and device characteristics of the 2 study groups were similar. All procedures in the cabin group were performed as planned without increase in duration or complication rate compared with the control group. The mean radiation dose to the head, normalized for fluoroscopy duration, was significantly lower in the cabin (0.040 ± 0.032 μSv/min) than in the control (1.138 ± 0.560 μSv/min) group (p < 0.0001). The radiation doses to the thorax (0.043 ± 0.027 vs 0.041 ± 0.040 μSv/min) and back (0.038 ± 0.029 vs 0.033 ± 0.018 μSv/min) in the cabin versus control group (under the apron) were similar. Conclusions: The use of a radiation protection cabin markedly decreased the exposure of the operator to radiation, and eliminated the need to wear a lead apron, without increasing the procedural time or complication rate during implantation of pacemaker and ICD. (J Cardiovasc Electrophysiol, Vol. 21, pp. 428–430, April 2010)     

Course of infection by Babesia sp. BQ1 (Lintan) and B. divergens in sheep depends on the production of IFNγ and IL10

Ovine babesiosis is an important disease in China and responsible for economic losses. Several Babesia strains are involved, but Babesia sp. BQ1 (Lintan) and Babesia sp. BQ1 (Ningxian) are particularly prevalent in the Guansu region. Babesia divergens, in contrast, can experimentally infect spleen‐intact sheep, but does not induce clinical signs. The immune response of spleen‐intact sheep to Babesia sp. BQ1 (Lintan) and to B. divergens was therefore compared to identify the immune mechanisms involved in pathogenicity. The greater pathogenicity of Babesia sp. BQ1 (Lintan) than that of B. divergens was confirmed: sheep infected with Babesia sp. BQ1 (Lintan), but not with B. divergens, developed hyperthermia and showed patent parasitaemia in Giemsa‐stained blood smears from the ear vein. Furthermore, more parasites were also detected in the blood from the jugular vein of Babesia sp. BQ1 (Lintan)‐infected sheep. Pathogenicity of Babesia spp. involved cellular responses, but not humoral responses. Interferon‐gamma was produced only by specifically activated PBMC from B. divergens‐infected sheep and interleukin‐10 only by specifically activated PBMC from Babesia sp. BQ1 (Lintan)‐infected sheep. The role of these cytokines in the course of infection by Babesia spp. is discussed.     

European guidelines for the certification of professionals in sleep medicine: report of the task force of the European Sleep Research Society

In recent years, sleep medicine has evolved into a full-grown discipline, featuring a multidisciplinary approach to diagnosis and treatment of patients with sleep disorders. Sleep medicine cuts across the boundaries of different conventional disciplines and is therefore open to medical and non-medical professionals with different specialty backgrounds. The aim of the current paper is to introduce a qualification for those professionals whose main occupation is to practice sleep medicine in the setting of a sleep medicine centre. The drafting of guidelines dealing with requirements for such qualification was entrusted to a task force by the European Sleep Research Society. The guidelines are the result of a progressive consensus procedure in which standards were defined for education, training, and evaluation. The final step along this pathway is a theoretical and practical examination, providing proof of proficiency in the field of sleep medicine. This paper describes the object of specific competences, the scope of sleep medicine, and the qualification procedures that pertain to three professional categories: medical specialists, non-medical professionals with a university master degree (such as psychologists and biologists), and nurses and technologists. Indices of preceding practical experience and theoretical knowledge are presented in Appendices 1 and 2 . These guidelines are a European standard. They may be adapted in the future according to new scientific insights. National certification programs that comply with these guidelines may be subject to homologation by the ESRS.