Paolo Zecchi

Electromagnetic interference of digital and analog cellular telephones with implantable cardioverter defibrillators: in vitro and in vivo studies.

The present study examines the potential electromagnetic interference effects induced by cellular telephones on ICDs. We developed ad hoc protocols to conduct both in vitro and in vivo trials on most of the implantable cardioverter defibrillators available on the international market. Trials were conducted with three cellular telephones: two GSM (Global System for Mobile Communication) and one TACS (Total Access Communication System). A human trunk simulator was used to carry out in vitro observations on six ICDs from five manufacturers. In vivo tests were conducted on 13 informed patients with eight different ICD models. During the trials in air, GSM telephones induced interference effects on 4 out of the 6 cardioverter defibrillators tested. Specifically, pulse inhibition, reprogramming, false ventricular fibrillation, and ventricular tachycardia detections occurred, which would have entailed inappropriate therapy delivery had this been activated. Effects were circumscribed to the area closely surrounding the connectors. When the ICD was immersed in saline solution, no effects were observed. Three cases of just ventricular triggering with the interfering signal were observed in vivo.

Safety and Feasibility of Coronary Sinus Left Ventricular Leads Extraction: A Preliminary Report

Background: transvenous positioning of the left ventricular (LV) lead in a branch of the coronary sinus (CS) is generally the preferred implantation technique in biventricular pacing. Very few data are reported about removal of LV pacing leads positioned in a CS branch. Aim of the study was to describe our experience with percutaneous extraction of LV pacing leads in order to evaluate feasibility and safety of this procedure.Methods: we enrolled 392 patients who underwent a biventricular pacing implant. The indication for catheter removal was considered in case of definite diagnosis of infection and in some cases of lead dislodgement or diaphragmatic stimulation. LV lead extraction was first attempted by manual traction; in case of failure a locking stylet or locking stylet plus radiofrequency could be used.Results: twelve of 392 patients implanted needed LV lead removal. The leads had been in place for 13.9 ± 11.7 months. Extraction was indicated in 5 of them for LV lead dislodgement or diaphragmatic stimulation, and in 7 patients for lead infection. In all cases manual traction succeeded to remove the LV lead. In 7 cases of infection, the right atrial and ventricular leads were removed. The mean total procedure time was 69 ± 22 min. No complications were observed.Conclusions: our study suggests that CS leads could be easily and safely removed without any complication, also when placed in a CS branch, at least for relatively young catheters.

A Randomized Comparison of Alternative Techniques to Achieve Coronary Sinus Cannulation During Biventricular Implantation Procedures

AbstractIntroduction: Biventricular pacing system implantation is a time-consuming and challenging procedure. A critical step in biventricular pacemaker implantation is coronary sinus (CS) cannulation. CS cannulation can be achieved either using dedicated guiding catheters (guiding catheter alone positioning strategy, GCA) or with the aid of an electrophysiology catheter advanced inside the guiding catheter (electrophysiology catheter aided positioning strategy, EPA). Aim of the study: To evaluate whether the EPA technique is useful for reducing CS cannulation time compared to a conventional GCA technique. Methods: Thirty-four consecutive patients were randomly assigned to the GCA (18 patients) or EPA (16 patients) CS cannulation strategy. Results: Time to successful catheterization of CS was 5.0 ± 2.4 min in the EPA group versus 10.1 ± 5.4 min in the GCA group p = 0.004. Fluoroscopy time was 4.6 ± 2.3 min in the EPA group versus 9.2 ± 4.9 min in the GCA group p = 0.004. Total contrast dye volume to search and engage the CS ostium was 0.0 ml in the EPA group versus 14.3 ± 3.4 ml in the GCA group p < 0.001. Conclusions: Cannulation of CS with the adjunct of an electrophysiology catheter to dedicated delivery systems significantly reduces procedural time, fluoroscopy time and contrast dye volume compared to a conventional strategy.

Right ventricular substrate mapping using the Ensite Navx system: Accuracy of high-density voltage map obtained by automatic point acquisition during geometry reconstruction

BACKGROUND Contact point-to-point electroanatomic mapping (Pt-Map) is a validated tool to evaluate right ventricular (RV) substrate. When using the EnSite NavX system (St. Jude Medical, St Paul, Minnesota), geometry reconstruction by dragging the mapping catheter (Geo-Map) allows for quicker acquisition of a large number of points and better definition of anatomy, but it is not validated for substrate mapping. OBJECTIVE This study evaluates the feasibility and accuracy of Geo-Map. METHODS Thirteen patients (mean age 38 +/- 12 years) with RV arrhythmias and an apparently normal heart underwent cardiac magnetic resonance imaging (MRI), Pt-Map, and Geo-Map. The 2 maps were compared in terms of mapping procedural time, radiation time, and total number of points acquired. We finally compared the number and characteristics of low-potential areas on each patients Pt-Map, Geo-Map, and cardiac MRI. RESULTS Geo-Map required significantly shorter mapping and radiation times in comparison to Pt-Map (12.4 +/- 4.6 vs. 31.9 +/- 10.1 and 5.8 +/- 2.1 vs. 12.1 +/- 3.9, P <.001). Furthermore, Geo-Map was based on a significantly higher density of points in comparison to Pt-Map (802 +/- 205 vs. 194 +/- 38, P <.001). Taking into consideration the total number of RV regions analyzed, the Pt-Map and Geo-Map disagreed in 2 of 65 (3%) regions (P = NS), which only Geo-Map identified as low-potential areas and indeed corresponded to wall motion abnormalities on MRI. CONCLUSION Voltage maps obtained through RV geometry acquisition have accuracy comparable to that of conventional point-by-point mapping in detecting low-voltage areas, have a good correlation with MRI wall motion abnormalities, and allow a significant reduction in procedural time and x-ray exposure.

Rationale and design of the NO-PARTY trial: near-zero fluoroscopic exposure during catheter ablation of supraventricular arrhythmias in young patients

INTRODUCTION Radiofrequency catheter ablation is the mainstay of therapy for supraventricular tachyarrhythmias. Conventional radiofrequency catheter ablation requires the use of fluoroscopy, thus exposing patients to ionising radiation. The feasibility and safety of non-fluoroscopic radiofrequency catheter ablation has been recently reported in a wide range of supraventricular tachyarrhythmias using the EnSite NavX™ mapping system. The NO-PARTY is a multi-centre, randomised controlled trial designed to test the hypothesis that catheter ablation of supraventricular tachyarrhythmias guided by the EnSite NavX™ mapping system results in a clinically significant reduction in exposure to ionising radiation compared with conventional catheter ablation. METHODS The study will randomise 210 patients undergoing catheter ablation of supraventricular tachyarrhythmias to either a conventional ablation technique or one guided by the EnSite NavX™ mapping system. The primary end-point is the reduction of the radiation dose to the patient. Secondary end-points include procedural success, reduction of the radiation dose to the operator, and a cost-effectiveness analysis. In a subgroup of patients, we will also evaluate the radiobiological effectiveness of dose reduction by assessing acute chromosomal DNA damage in peripheral blood lymphocytes. CONCLUSIONS NO-PARTY will determine whether radiofrequency catheter ablation of supraventricular tachyarrhythmias guided by the EnSite NavX™ mapping system is a suitable and cost-effective approach to achieve a clinically significant reduction in ionising radiation exposure for both patient and operator.

Electrograms for identification of the atrial ablation site during catheter ablation of accessory pathways.

Background: Catheter ablation of accessory pathways using radiofrequency current has been shown to be effective in patients with Wolff‐Parkinson‐White syndrome, by using either the ventricular or atrial approach. However, the unipolar electrogram criteria for identifying a successful ablation at the atrial site are not well established. Methods and Results: One hundred patients with Wolff‐Parkinson‐White were treated by delivering radiofrequency energy at the atrial site. Attempts were considered successful when ablation (disappearance of the delta wave) occurred in < 10 seconds. In eight patients with concealed pathway, the accessory pathway location was obtained by measuring the shortest V‐A interval either during ventricular pacing or spontaneous or induced reciprocating tachycardia. In 92 patients both atrioventricular valve annuli were mapped during sinus rhythm, in order to identify the accessory pathway (K) potential before starting the ablation procedure. When a stable filtered (30–250 Hz) “unipolar” electrogram was recorded, the following time intervals were measured: (1) from the onset of the atrial to the onset of the K potential (A‐K); (2) from the onset of the delta wave to the onset of the K potential (delta‐K); and (3) from the onset of the K potential to the onset of the ventricular deflection (K‐ V). During unsuccessful versus successful attempts, A‐K (51 ± 11 ms vs 28 ± 8 ms, P < 0.0001 for left pathways [LPs]; and 44 ± 8 ms vs 31 ± 8 ms, P < 0.02 for right pathways [RPs]) and delta‐K intervals (2 ± 9 ms vs ‐18 ± 10 ms, P < 0.0001 for LPs; and 13 ± 7 ms vs 5 ± 8 ms, P < 0.02 ms for RPs) were significantly longer. Conclusions: Short A‐K interval (< 40 ms), and a negative delta‐K interval recorded from the catheter positioned in the atrium are strong predictors of successful ablation of LPs and RPs. Therefore, the identification of the K potential appears to be of paramount importance for positioning of the ablation catheter, followed by analysis of A‐K and delta‐K unipolar electrogram intervals. However, it appears that the mere recording of K potential is not, per se, predictive of successful outcome, but rather the A‐K and delta‐K interval.

Fossa ovalis radiofrequency perforation in a difficult case of conventional transseptal puncture for atrial fibrillation ablation

A 65-year-old man was referred for atrial fibrillation ablation to our center. Routine pre-procedure transthoracic and transoesophageal echocardiography and cardiac computed tomography examinations showed a normal interatrial septum and fossa ovalis anatomy. Access to left atrium was initially planned using a conventional transseptal needle puncture. During the procedure, several consecutive attempts in conjunction with intracardiac echocardiography support, failed to cross the septum. The procedure was then successfully carried out using a specifically designed radiofrequency transseptal catheter.

The linear ablation of atrial fibrillation in the Right atrium: Can the isthmus ablation improve its efficacy?

AbstractObjectives: The aims of this study were to compare the efficacy of a 2- versus a 3 RF lesions ablation procedure in the RA in patients with paroxysmal AF, and to map right atrial activation during AF. Background: RF catheter-mediated ablation lines mimicking the Maze operation have been proposed as a novel curative approach for AF. The relationship between this type of ablation and right atrial mapping has not been extensively studied. Methods: Twenty-four patients with recurrent, drug-refractory, paroxysmal AF underwent an extensive mapping of the RA before attempting linear lesion RF ablation. Patients were divided into two groups: 15 patients received two linear lesions (Group 1), 9 patients three linear lesions (Group 2). Results: One-month success rate AF did not recur in 40% of Group 1 patients (6/15) and in 66% (6/9) of Group 2 patients. 27% of patients in Group 1 and 11% of patients in Group 2 had recurrences controlled by drugs. No benefit in 33% of Group 1 patients and 22% of Group 2. Long-term follow-up In the absence of any drug treatment, no AF recurrences were observed in 26% of Group 1 patients (FU: 23 to 47 months) and 55% of Group 2 (FU: 14 to 23 months). No complications were reported. Conclusions: Right atrial linear ablation is safe and may be proposed for AF treatment in selected patients.

A 60-year-old man with chest pain following pacemaker implantation.

A 60-year-old man with variant angina was taking verapamil to prevent coronary spasm. Symptomatic second-degree atrioventricular block developed, and he required implantation of a permanent dual-chamber pacemaker. However, during the implantation procedure, repeated attempts to penetrate the left

Which Patients with ICD May Really Benefit from DDD Pacing, and Which Won’t?

The efficacy of implantable cardioverter-defibrillators (ICD) in preventing sudden death has been shown by several trials. Nonetheless two functions need to be improved: (1) the identification of arrhythmias other than VF (supraventricular or ventricular fibrillation) in order to reduce inappropiate shocks, (2) the quality of cardiac pacing. Dual-chamber pacing should be the stimulation method of choice in patients with depressed sinus node function, or in those who are pacemaker dependent, when effective atrial pacing and sensing can be achieved. In contrast, patients with an implatable cardioverter defibrillator (ICD) who also need antibradycardia pacing, can currently receive only fixed rate ventricular pacing, even though most of them have depressed sinus node function. Furthermore, positive hemodynamic effects of atrioventricular sequential pacing in patients with left ventricular dysfunction have been described so far [1, 2]. In fact the preservation of atrioventricular synchronization can result in a positive effect on the morbility and perhaps on the mortality of pacemaker dependent patients [1].