Joint Position Paper of the Working Group of Pacing and Electrophysiology of the French Society of Cardiology (SFC) and the Société française d'imagerie cardiaque et vasculaire diagnostique et interventionnelle (SFICV) on magnetic resonance imaging in patients with cardiac electronic implantable devices.

Magnetic resonance imaging (MRI) has become the reference imaging for the management of a large number of diseases. The number of MR examinations increases every year, simultaneously with the number of patients receiving a cardiac electronic implantable device (CEID). A CEID was considered an absolute contraindication for MRI for years. The progressive replacement of conventional pacemakers and defibrillators by MR-conditional CEIDs and recent data on the safety of MRI in patients with "MR-nonconditional" CEIDs have progressively increased the demand for MRI in patients with a CEID. However, some risks are associated with MRI in CEID carriers, even with "MR-conditional" devices because these devices are not "MR-safe". A specific programing of the device in "MR-mode" and monitoring patients during MRI remain mandatory for all patients with a CEID. A standardized patient workflow based on an institutional protocol should be established in each institution performing such examinations. This joint position paper of the Working Group of Pacing and Electrophysiology of the French Society of Cardiology and the Société française d'imagerie cardiaque et vasculaire diagnostique et interventionnelle (SFICV) describes the effect and risks associated with MRI in CEID carriers. We propose recommendations for patient workflow and monitoring and CEID programming in MR-conditional, "MR-conditional nonguaranteed" and MR-nonconditional devices.

Comparative anatomy and angiography of the cardiac coronary venous system in four species: human, ovine, porcine, and canine.

INTRODUCTION: The coronary arterial system has been the subject of greater investigation than its venous system due to the importance of human coronary artery disease. With the advent of new percutaneous treatments, the anatomy of the coronary venous system has increasing relevancy. We compared the organization of the coronary venous circulation in three species commonly used in research and compared these to normal humans using both macroscopic anatomic and angiographic studies. ANIMALS: The anatomy of five explanted hearts from healthy dogs, pigs, and sheep were studied macroscopically, and 10 explanted hearts per animal species and 10 clinically normal human were examined by angiography. METHODS: Animal hearts were injected with latex and dissected macroscopically. The coronary venous system of humans was evaluated from clinical angiographic studies. In the animal hearts, a retrograde angiographic study was performed via a Foley catheter in the coronary sinus. RESULTS: The general organization of the coronary venous circulation was similar among humans, dogs, sheep, and pigs. Despite overall similarities to humans, animal hearts demonstrated the absence of the oblique vein of the left atrium and differences in position and organization of venous valves; venous diameters; number of tributary veins; and presence of an anastomosis between the left and right (human anterior and posterior) venous tree. The left azygos of the pig and sheep joined the coronary sinus. CONCLUSIONS: Anatomical differences must be considered when planning biomedical and veterinary studies incorporating cardiac veins. This study provides baseline data regarding structure and organization of the cardiac venous system.

Imaging paleoslabs in the D″ layer beneath Central America and the Caribbean using seismic waveform inversion.

D″ (Dee double prime), the lowermost layer of the Earth's mantle, is the thermal boundary layer (TBL) of mantle convection immediately above the Earth's liquid outer core. As the origin of upwelling of hot material and the destination of paleoslabs (downwelling cold slab remnants), D″ plays a major role in the Earth's evolution. D″ beneath Central America and the Caribbean is of particular geodynamical interest, because the paleo- and present Pacific plates have been subducting beneath the western margin of Pangaea since ~250 million years ago, which implies that paleoslabs could have reached the lowermost mantle. We conduct waveform inversion using a data set of ~7700 transverse component records to infer the detailed three-dimensional S-velocity structure in the lowermost 400 km of the mantle in the study region so that we can investigate how cold paleoslabs interact with the hot TBL above the core-mantle boundary (CMB). We can obtain high-resolution images because the lowermost mantle here is densely sampled by seismic waves due to the full deployment of the USArray broadband seismic stations during 2004-2015. We find two distinct strong high-velocity anomalies, which we interpret as paleoslabs, just above the CMB beneath Central America and Venezuela, respectively, surrounded by low-velocity regions. Strong low-velocity anomalies concentrated in the lowermost 100 km of the mantle suggest the existence of chemically distinct denser material connected to low-velocity anomalies in the lower mantle inferred by previous studies, suggesting that plate tectonics on the Earth's surface might control the modality of convection in the lower mantle.

[Rate control in patients with atrial fibrillation]. / Contrôler la fréquence ventriculaire?

The objectives of rate control in patients with atrial fibrillation is to reduce symptoms, improve quality of live and minimize the risk of heart failure development. Based upon results of large randomized studies, this strategy can be chosen as a first line therapy in some patients including those with heart failure. The target ventricular rate is

[The best of arrhythmia in 2005]. / L'essentiel de 2005 en rythmologie.

In 2005, one of the major areas of interest in the field of electrophysiology remains ablation of atrial fibrillation (AF). Identification of specific atrial sites, likely playing a role in the perpetuation of this arrhythmia has taken part in the ablation technique refinement. An increase in the rate of asymptomatic AF following ablation has been reported this year, which underlined the need for long lasting ECG recordings to demonstrate ablation success. The role of ventricular programmed stimulation remained controversial in the management of Brugada syndrome. Nevertheless, in the report of the second consensus conference, result of ventricular programmed stimulation was still considered as important in the decision making process. The third form of short QT syndrome (SQT3) has been found to be caused by a mutation in the KCNJ2 gene, leading to an increase in the function of Ik1 channel. Right ventricular dilation seemed to be the most frequent echocardiography anomaly in patients with right ventricular dysplasia as defined by the criteria published in 1994. Ablation of frequent (>20% on Holter monitoring) ventricular premature beats has been shown to improve hemodynamics in patients with left ventricular dilation and impaired ejection fraction. Safety and efficacy of implantable cardioverter defibrillator (ICD) have been demonstrated in high risk patients with hypertrophic cardiomyopathy in a large clinical study. However, the use of high energy ICD and the systematic determination of the defibrillation threshold were recommended. Despite the presence of sophisticated algorithms to discriminate VT from SVT, high rates of inappropriate therapies were still reported in recent ICD studies.

[The best of arrhythmia in 2004]. / L'essentiel de 2004 en rythmologie.

As for the preceding years, important studies regarding several remaining clinical issues for electrophysiologists have been reported in 2004. Large randomized studies have underlined the need for an EP study in asymptomatic patients with overt ventricular preexcitation. In addition to a short antegrade refractory period, arrhythmia induction (atrial fibrillation or reciprocating tachycardia) argues for accessory pathway ablation. Although currently leading to fairly good results, atrial fibrillation ablation technique is still evolving. Encircling pulmonary vein and the surrounding atrial tissue seems to give better long term clinical results as compared to ostial pulmonary vein disconnection. Large series have confirmed that whatever cardiomyopathy etiology, prophylactic ICD implantation was associated with a reduction of sudden arrhythmic death during follow-up in patients with low ejection fraction. However, in order to save one patient more and more patients have to be implanted because of the increasing efficacy of pharmacological treatment for heart failure. Three clinical series of arrhythmogenic right ventricular dysplasia implanted with AICD have been published this year. The prognostic factors for the occurrence of severe ventricular arrhythmia are hemodynamically ill tolerated ventricular tachycardia, and VT induction during EP study. Management of patients with Brugada syndrome is still far from being well defined. Interestingly in a recent report, hydroquinidine has been found to reduce the incidence of ventricular arrhythmia in the follow-up as well as the rate of ventricular arrhythmia induction in the EP lab. Yet, prophylactic ICD implantation remains the treatment of choice in symptomatic and inducible patients.

[Coronary sinus in rhythmology]. / Le sinus coronaire en rythmologie.

Because of its complex anatomical structure and its position in the heart, the coronary sinus, plays a major role in many diagnostic and therapeutic EP procedures. Anatomy of the coronary sinus is crucial during biventricular pacemaker implantation. Mapping of the coronary sinus is of primary importance during left-sided accessory pathway evaluation and ablation. More recently, the coronary sinus musculature and its connections to left and right atrium and to left ventricle have been identified as playing an important role in various types of supraventricular arrhythmias.

Myocardial connections between left atrial myocardium and coronary sinus musculature in man.

INTRODUCTION: Anatomic studies have shown that muscle morphologically identical to that of the atrial myocardium consistently surrounds the coronary sinus (CS). The CS musculature is connected to the left atrial (LA) myocardium in a variable fashion, with fewer connections in its distal portion. The aim of this study was to document the presence of connections between the LA myocardium and the CS musculature, using pacing maneuvers in man, and to study their potential association with natural atrial arrhythmia occurrence. METHODS AND RESULTS: Thirty patients (19 men; mean age 50.5 years) underwent electrophysiologic study, during which a decapolar catheter with 2-mm interelectrode spacing every 10 mm was inserted into the CS, with the proximal electrode pair positioned at the ostium. Associated atrial arrhythmias were paroxysmal atrial fibrillation in 5, typical atrial flutter in 13, LA flutter in 1, and other in 11. Baseline S1 and a single extrastimulus were delivered during distal and proximal CS pacing, while recordings were obtained from the four remaining bipoles. During distal CS pacing, double potentials with increasing interpotential interval from proximal to distal CS as a function of extrastimulus prematurity were detected in nine patients, suggesting block in a discrete local pathway distally connecting the CS to the LA and leading to reversion of low LA activation. Local delay in this pathway without complete CS-LA block resulting in LA activation fusion was observed in eight patients. A single nonfractionated potential at the distal CS, even at the shortest attainable S1-S2 coupling interval, which was interpreted as no block within distal CS-LA connection(s), was observed in the other 13 patients. History of atrial fibrillation or atypical atrial flutter was found in 8 of 9 patients with block at the distal CS-LA connection but in only 3 of 13 patients with no CS-LA connection block (P = 0.004). CONCLUSION: The ability to dissociate the LA from the distal CS suggests the presence of discrete connections between these structures in man. This observation appears to be associated with the clinical occurrence of atrial arrhythmias.

Catheter ablation of typical atrial flutter: a randomized comparison of 2 methods for determining complete bidirectional isthmus block.

BACKGROUND: Complete bidirectional isthmus conduction block (CBIB) was initially assessed by sequential detailed activation mapping at both sides of the ablation line during proximal coronary sinus and anteroinferior right atrium pacing. Mapping only the ablation line ("on-site" atrial potential analysis) was recently reported as a means of CBIB identification. The study was designed to compare these 2 techniques prospectively regarding the diagnosis of CBIB. METHODS AND RESULTS: In 76 consecutive patients (mean age, 63.4+/-10.5 years), typical atrial flutter ablation was performed using either the activation mapping technique (group I) or on-site atrial potential analysis (group II). Criteria for CBIB using on-site atrial potential analysis was the recording of parallel, widely spaced double atrial potentials along the ablation line. The CBIB criterion was retrospectively searched using the alternative technique at the end of the procedure. In successful patients, the mean radiofrequency delivery duration was longer in group II (845+/-776 versus 534+/-363 s; P:=0.03). On-site, clear-cut, widely spaced double atrial potentials and activation mapping suggesting CBIB were concomitantly observed in only 47 patients (54%), and ambiguous/atypical double potentials were recorded in 31 patients (39%). CONCLUSIONS: Although feasible, the on-site atrial potential analysis seemed to be inferior to the classic activation mapping technique, mainly because of the ambiguity of electrogram interpretation along the ablation line. However, when combined with the activation mapping technique, it provided additional information regarding isthmus conduction properties in some cases. Therefore, optimally, both methods should be used concomitantly.

Comparison of effectiveness of an 8-mm versus a 4-mm tip electrode catheter for radiofrequency ablation of typical atrial flutter.

An 8-mm catheter does not appear superior to 4-mm tip electrode for atrial flutter ablation. The potential advantage of allowing higher energy delivery on a larger surface is compensated by the lack of consistent contact with the endocardial surface.

Randomized comparison of two targets in typical atrial flutter ablation.

Typical atrial flutter ablation has become anatomically guided to 2 separate sites within the isthmus at the inferior right atrium: (1) between the inferior vena cava and the tricuspid annulus (anterior side of the isthmus [A]), (2) between the eustachian crest, the coronary sinus ostium and tricuspid annulus (posterior side of the isthmus [P]). We prospectively compared ablation results at these sites in 72 consecutive patients. Patients were randomized in group P or A according to the initial target site. If ablation failed at 1 site after 15 radiofrequency (RF) pulses, the other side of the isthmus was targeted. Before 15 RF pulses, complete bidirectional isthmus block was achieved in 30 of 36 group A patients and in 25 of 36 group P patients, with similar mean RF pulses number, procedure time, and fluoroscopy time. After shifting to the other target, success was finally obtained at P in 2 of 6 group A patients, and at A in 8 of 11 group P patients before a maximum of 30 RF pulses. Among successful patients, number of RF pulses, procedure time, and fluoroscopy time were significantly lower in group A (7.2 +/- 5.4 vs 11.0 +/- 8.1 pulses, p = 0.03; 131 +/- 44 vs 163 +/- 66 minutes, p = 0.03; 31 +/- 19 vs 46 +/- 24 minutes, p = 0.01, respectively). Impairment of atrioventricular (AV) nodal conduction occurred in 5 patients only during ablation at P. AV block was transient in 4 patients and permanent in 1. Although atrial flutter ablation is equally effective at P and A, success seems easier to obtain when A is first targeted. Ablation at P is associated with a significant risk of AV block.

[New invasive cartography techniques in electrophysiology]. / Les nouvelles techniques de cartographie invasive en électrophysiologie.

Fulguration, a widely used technique in the 80s, has been replaced by radiofrequency ablation. The limited and better controlled intra-cardiac lesions obtained by this method allowed the elimination of a large number of tachycardias with a high success rate. However, there are many arrhythmias, particularly at the atrial level, which are so complex that a limited analysis at a number of points of endocardial recording is inadequate. Recently, a number of systems has been introduced which considerably increased the acuity of observation of arrhythmias and the efficacy of their ablation. First of all, there are improved techniques of classical electrophysiological recording. Then, new systems of temporo-spatial recordings were developed and are described in this article. These use computer systems and enable particularly reliable and detailed approaches to cardiac anatomy and electrophysiology. However, the optimal use of these techniques can only be in specialised centres, by highly trained cardiologists in classical electrophysiology, for which they are complementary to rather than substitute for.

Pacing in prevention of atrial fibrillation: the PIPAF studies.

The PIPAF trials are a set of randomized multicenter studies which seeks to evaluate the potential preventive effect of different modes of pacing in patients with drug refractory paroxysmal atrial fibrillation by means of a permanent pacemaker. The objective of the studies are (1) to significantly prolong the time to first recurrence of atrial arrhythmia and (2) to significantly reduce the cumulative arrhythmia duration. The role of the atrial pacing site (left or right), the overdriving of the sinus rate, and the suppression of the post extrasystolic compensatory pause are evaluated alone or in association, giving rise to four distinct pacing protocols. Over a period of 2 years, 220 patients will be included in 35 centers from 5 different countries.

Entrainment of typical AV nodal reentrant tachycardia using para-Hisian pacing: evidence for a lower common pathway within the AV node.

INTRODUCTION: Despite the ability to cure atrioventricular nodal reentrant tachycardia (AVNRT) by radiofrequency catheter ablation with a high success rate, the exact localization of the tachycardia circuit is still not well established. The presence of AV nodal tissue between the typical AVNRT circuit and the His bundle, constituting a lower common pathway (LCP), remains controversial. METHODS AND RESULTS: Entrainment of AVNRT during para-Hisian stimulation allows accurate measurement of the His- to- atrial (HA) interval which is part of the same circuit as that of the tachycardia. With an LCP, during tachycardia, there is simultaneous conduction from the low turnaround of the circuit to the atrium (via the fast pathway) and to the His bundle (via the LCP). However, during entrainment by para-Hisian pacing, the impulse has to retrogradely depolarize sequentially the LCP and the fast pathway. Therefore, in the presence of an LCP, the HA interval duration during tachycardia (HAt) should be shorter than that of during entrainment by para-Hisian stimulation (HAe). We considered an LCP present when Hae - HAt was > or = 10 msec. Entrainment of typical AVNRT with para-Hisian stimulation was performed in 23 consecutive patients (21 females) with a mean age of 45+/-17 years. LCP was considered to be present in 18 of 23 patients (78%). In addition, transient His-bundle dissociation from the ongoing tachycardia occurred in seven patients (30%). CONCLUSION: These results support the presence of a LCP during typical AVNRT.

Presence and significance of the left atrionodal connection during atrioventricular nodal reentrant tachycardia.

It has been suggested that the anatomic substrates of dual atrioventricular nodal pathways are likely to be the atrionodal connections. During atrioventricular nodal re-entrant tachycardia (AVNRT) or ventricular pacing (VP), an earliest retrograde atrial activation in the coronary sinus (CS) distal to the ostium (CS breakthrough) would suggest the presence of an exit from a left atrionodal connection. The aim of the study was to evaluate the incidence of such an atrial retrograde activation in the CS during AVNRT and VP. The retrograde atrial activation was recorded during typical AVNRT (38 patients, 27 women, mean age 44 +/- 18 years) by a multipolar catheter in the CS, a decapolar catheter in the His bundle position, and a deflectable quadripolar catheter along the tricuspid annulus anterior to the CS ostium. In 31 patients the retrograde atrial activation was recorded also during VP at a similar cycle length. A CS breakthrough was found in 18 patients during AVNRT (47%) and in 13 patients during VP (42%). Presence or absence of CS breakthrough was concordant between AVNRT and VP in 90% of the patients. A CS breakthrough, suggesting a left-sided atrionodal connection, is frequently recorded both during AVNRT and VP. In patients with a CS breakthrough pattern, the absence of correlation between the His bundle to the earliest CS retrograde atrial electrogram interval and AVNRT cycle length, or any other atrial activation times recorded in the posterior and anterior region of the Koch's triangle, would suggest that the left-sided atrionodal connection is a bystander during typical AVNRT.

[Indications for electrophysiological investigation of tachycardia]. / Indications des explorations électrophysiologiques dans les tachycardies.

Cardiologists are often confronted by the situation of discussing the indications for invasive electrophysiological procedures. In this field, the recommendations of American scientific societies have been published but they are relatively dated and require updating. These procedures require the introduction of one or more catheters by a femoral venous or arterial approach, or by the endoesophageal route for positioning at different sites in the heart. The first stage of the procedure is usually to evaluate the electrophysiological properties of the cardiac chamber under investigation; followed by provocative manoeuvres such as electrical stimulation, injection of a drug, the delivery of a CEE electrical shock percutaneously or by an intracardiac radiofrequency stimulation, according to the type of procedure or the centre concerned. Schematically, the indications of these procedures may be determined in different contexts according to the benefits that may be expected in a given clinical situation. This article is devoted to the principal rhythmological situations which may be encountered but, however, the indications of radiofrequency ablation are not discussed.

How smart should pacemakers Be?

The concept of the "smart" pacemaker has been continuously changing during 40 years of progress in technology. When we talk today about smart pacemakers, it means optimal treatment, diagnosis, and follow-up for patients fitting the current indications for pacemakers. So what is smart today becomes accepted as "state of the art" tomorrow. Originally, implantable pacemakers were developed to save lives from prolonged episodes of bradycardia and/or complete heart block. Now, in addition, they improve quality of life via numerous different functions acting under specific conditions, thanks to the introduction of microprocessors. The devices have become smaller, with the miniaturization of the electrical components, without compromising longevity. Nevertheless, there are still some unmatched objectives for these devices, for example, the optimization of cardiac output and the management of atrial arrhythmias in dual-chamber devices. Furthermore, indications continue to evolve, which in turn require new, additional functions. These functions are often very complex, necessitating computerized programming to simplify application. In addition, the follow-up of these devices is time-consuming, as appropriate system performance has to be regularly monitored. A great many of these functions could be automatically performed and documented, thus enabling physicians and paramedical staff to avoid losing time with routine control procedures. In addition, modern pacemakers offer extensive diagnostic functions to help diagnose patient symptoms and pacemaker system problems. Different types of data are available, and their presentation differs from one company to the other. This huge amount of data can only be managed with automatic diagnostic functions. Thus, the smart pacemaker of the near future should offer high flexibility to permit easy programming of available therapies and follow-up, and extensive, easily comprehensible diagnostic functions.

Radiofrequency catheter ablation of common atrial flutter: significance of palpitations and quality-of-life evaluation in patients with proven isthmus block.

BACKGROUND: Creation of a complete bidirectional inferior vena cava-tricuspid annulus isthmus block (CBIB) by radiofrequency catheter ablation is now a well-accepted criterion for prevention of common atrial flutter (AFl) recurrences. However, some patients still complain of palpitations after ablation, and it is not known whether these are related to AFl recurrences or to other arrhythmias. METHODS AND RESULTS: Among 100 consecutive patients referred to our institution for AFl ablation, CBIB was created in 83. There were 54 patients (group A) in whom AFl was the only documented arrhythmia before ablation and 29 patients (group B) in whom atrial fibrillation (AFib) had been documented in addition to AFl. An electrophysiological control study was performed in 40 patients 1 to 3 months after ablation. Arrhythmic events, medications, and functional status were evaluated at midterm follow-up (n=77; 14. 7+/-8.4 months; range, 4 to 34 months). The SF-36 questionnaire and the Symptom Checklist--Frequency and Severity Scale specific for cardiac arrhythmia were used to assess quality of life in 63 patients at long-term follow-up (27.1+/-8.5 months). Recurrence of AFl was documented in only 1 patient 6 months after ablation. AFib was recorded in 28 patients (36.4%), and atypical AFl was found in 3 patients. Thirty-two group A patients (66.7%) and 17 group B patients (58.6%) were still arrhythmia free at midterm follow-up. Even at long-term follow-up and in group B patients, AFl ablation was followed by a clear improvement in quality of life. CONCLUSIONS: Palpitations after creation of CBIB are due mostly to AFib but not to AFl recurrence. This technique provides a significant and persistent clinical benefit and may suppress all atrial arrhythmia in a subset of patients suffering from both AFl and AFib.