Minimal fluoroscopy approach for right-sided supraventricular tachycardia ablation with a novel ablation technology: Insights from the multicenter CHARISMA clinical registry.

BACKGROUND: No data exist on the ability of the novel Rhythmia 3-D mapping system to minimize fluoroscopy exposure during transcatheter ablation of arrhythmias. We report data on the feasibility and safety of a minimal fluoroscopic approach using this system in supraventricular tachycardia (SVT) procedures. METHODS: Consecutive patients were enrolled in the CHARISMA registry at 12 centers. All right-sided procedures performed with the Rhythmia mapping system were analyzed. The acquired electroanatomic information was used to reconstruct 3-D cardiac geometry; fluoroscopic confirmation was used whenever deemed necessary. RESULTS: Three hundred twenty-five patients (mean age = 56 ± 17 years, 57% male) were included: 152 atrioventricular nodal reentrant tachycardia, 116 atrial flutter, 41 and 16 right-sided accessory pathway and atrial tachycardia, respectively. Overall, 27 481 s of fluoroscopy were used (84.6 ± 224 s per procedure, equivalent effective dose = 1.1 ± 3.7 mSv per patient). One hundred ninety-two procedures (59.1%) were completed without the use of fluoroscopy (zero fluoroscopy, ZF). In multivariate analysis, the presence of a fellow in training (OR = 0.15, 95% CI: 0.05-0.46; p = .0008), radiofrequency application (0.99, 0.99-1.00; p = .0002), and mapping times (0.99, 0.99-1.00; p = .042) were all inversely associated with ZF approach. Acute procedural success was achieved in 97.8% of the cases (98.4 vs. 97% in the ZF vs. non-ZF group; p = .4503). During a mean of 290.7 ± 169.6 days follow-up, no major adverse events were reported, and recurrence of the primary arrhythmia was 2.5% (2.1 vs. 3% in the ZF vs. non-ZF group; p = .7206). CONCLUSIONS: The Rhythmia mapping system permits transcatheter ablation of right-sided SVT with minimal fluoroscopy exposure. Even more, in most cases, the system enables a ZF approach, without affecting safety and efficacy.

Early rhythm-control ablation therapy to prevent atrial fibrillation recurrences: Insights from the CHARISMA Registry.

BACKGROUND: An early, comprehensive rhythm-control therapy is needed in order to treat atrial fibrillation (AF) effectively and to improve ablation outcomes. METHODS: A total of 153 consecutive patients from the CHARISMA registry undergoing AF ablation at eight centers were included. Patients with de novo PVI were classified as having undergone early treatment (ET) if the procedure was performed within 6 months after the first AF episode, and as having undergone delayed treatment (DT) if ablation was performed over 6 months after the first AF episode. RESULTS: One-hundred fifty-three patients were enrolled (69.9% male, 59 ± 10 years, 61.4% paroxysmal AF, 38.6% persistent AF). The time from the first AF episode to the ablation procedure was 1034 ± 1483 days. The ET group comprised 36 patients (25.3%), the DT group 60 (39.2%) and Redo cases were 57 (37.3%). During a mean follow-up of 366 ± 130 days, 18 patients (11.8%) suffered an AF/AT recurrence. More DT patients than ET patients suffered recurrences (15.7% vs. 2.2%, p = 0.0452) and the time to AT/AF recurrence was shorter in the group of patients who received an ablation treatment after 6 months (HR = 6.19, 95% CI: 1.7 to 21.9; p = 0.0474). On multivariate Cox analysis, only hypertension (HR = 4.86, 95% CI: 1.6 to 14.98, p = 0.0062) was independently associated with recurrences. Beyond the hypertension risk factor, ET was associated with a low risk of recurrence; recurrence rate ranged from 0% (ET patients without hypertension) to 25.0% (DT patients with hypertension). CONCLUSIONS: An early rhythm-control ablation therapy in the absence of common risk factors was associated with the lowest rate of recurrences.

An efficient algorithm based on electrograms characteristics to identify ventricular tachycardia isthmus entrance in post-infarct patients.

AIMS: Our study assesses the value of electrograms (EGMs) characteristics to identify a ventricular tachycardia (VT) isthmus entrance in patients with post-infarct VT. Post-infarct VTs are mostly due to a re-entrant circuit. A pacemapping (PM) approach is able to localize the VT isthmus during sinus rhythm. Limited data are available about the role of local EGMs in defining VT isthmus location. METHODS AND RESULTS: Twenty consecutive patients (70% male) referred for post-infarct VT catheter ablation were included in the present study. The VT isthmus was defined according to the PM method. At each recording site, 10 characteristics of the local EGM were assessed to predict the location of the VT isthmus entrance. In total, 924 EGMs were acquired, of which 127 were located in the VT isthmus entrance. Logistic regression analysis showed that bipolar voltage, number of EGM positive peaks, and sQRS interval were independently associated with VT isthmus entrance location. The ROC curve best fitted the model at the cut-off 0.1641 (sensitivity 72%, specificity 75.2%, positive predictive value 31.3%, negative predictive value 94.4%, area under the curve 0.78, P < 0.001). Based upon these results, we developed an algorithm implemented in an automatic calculator to determine the likelihood that an EGM is located at a VT isthmus entrance. CONCLUSION: Our study suggests that three EGM characteristics: bipolar voltage, number of positive peaks, and sQRS interval can successfully identify a VT isthmus entrance in post-infarct patients.

Very long-term outcome following transcatheter ablation of atrial fibrillation. Are results maintained after 10 years of follow up?

Aims: Atrial fibrillation (AF) transcatheter ablation is a safe and effective procedure. However, outcome over 10 years of follow-up has never been reported. The aim of this study is to assess outcome, describe predictors of recurrences, and report on quality of life (QoL) the decade after an AF ablation. Methods and results: Patients referred for AF ablation in a single high volume centre from June 2004 to June 2006 were enrolled and followed in a prospective fashion by yearly clinical assessment and Holter monitoring. Among 255 patients (42.7% paroxysmal AF, 77% males, after a follow-up of 125 ± 7 months), 132 (52%) were arrhythmia-free including (58, 32% after a single procedure) while 27 (10%) progressed to permanent AF. At multivariate analysis, a greater left atrium antero-posterior diameter (HR 1.05 95% CI 1.02-1.09, P = 0.02) related to arrhythmic recurrences, while no increase in blood pressure (HR 0.06 95% CI 0.02-0.20, P = 0.01), BMI (HR 0.06 95% CI 0.02-0.09, P < 0.001), and fasting glucose (HR 0.58 95% CI 0.36-0.92, P = 0.02) during follow-up were protective for arrhythmic recurrences. Overall QoL improved significantly, significantly related to the absence of recurrences, arrhythmic burden reduction and blood pressure, and BMI control (P < 0.001). Conclusion: The outcome of AF ablation over more than 10 years is characterized by a low incidence of progression towards permanent AF. Greater LA anteroposterior diameter related to arrhythmic recurrences, while blood pressure, BMI, and fasting blood glucose control emerged as predictors of sinus rhythm maintenance. Eventually, QoL improved significantly over the follow-up.

Autonomic Tone Activity Before the Onset of Atrial Fibrillation.

INTRODUCTION: The autonomic nervous system has been proven to play a major role in the onset of atrial fibrillation (AF), along with a predisposing substrate and a specific trigger event usually consisting of a premature supraventricular ectopic beat (SVEB). By means of heart rate variability (HRV) analysis, we investigated the activity of the autonomic nervous system before SVEBs nontriggering and triggering AF. METHODS AND RESULTS: We evaluated 28 patients with at least 1 episode of sustained AF (>30 seconds) recorded during 24-hour Holter monitorings. We performed HRV analysis during the hour preceding 35 AF onsets and compared these results with the HRV values before nontriggering SVEBs with similar prematurity. According to the low frequency (LF)/high frequency (HF) ratio in the 5 minutes before the onset, AF episodes were classified as either vagal (LF/HF ratio <1.5) or adrenergic (LF/HF ratio ≥1.5).Vagal episodes (16) showed a decrease in LF (from 50.81 ± 1.67 to 32.73 ± 3.54) and an increase in HF (from 36.00 ± 2.30 to 54.7 ± 3.69) throughout the hour preceding the onset. Adrenergic episodes (19) had opposite changes in LF (from 55.4 ± 4.95 to 67.51 ± 5.24) and HF (from 33.78 ± 5.82 to 27.96 ± 3.51) during the same period. No similar trends were observed before the selected nontriggering SVEBs. CONCLUSION: Only SVEBs occurring during a phase of hyperactivity of one of the 2 branches of the autonomic nervous system are able to trigger episodes of AF.

The dream of near-zero X-rays ablation comes true.

While radiation exposure related to natural sources plays a minor role, medicine-related exposure, represents, to date, a major exposure source. Within this exposure interventional electrophysiology is a relevant contributor. Unfortunately, no safe dose in radioprotection exists, the negative acute and long-term effects of radiological exposure may emerge at any radiation exposure dose. For this reason, patients and physicians should be aware of the risk of radiation exposure and the benefits of the imaging/procedure balanced by the required radiation exposure. Given this, performing a near to zero X-rays transcatheter ablation procedure should therefore represent an aim for all electrophysiological lab. Fortunately, the introduction of electroanatomic mapping systems, have provided the possibility to perform simple and complex electrophysiological procedures avoiding, or at least, limiting the use of radiations. The present review summarizes state of the art of feasibility and safety of the near to zero approach for the main electrophysiological procedures, highlighting the potential health benefits.

Early minimally invasive percutaneous fixation of displaced intra-articular calcaneal fractures with a percutaneous angle stable device.

The Minimally Invasive Reduction and Osteosynthesis System(®) (MIROS) is a percutaneous angle stable device for the treatment of fractures. The aim of the present study was to evaluate the clinical and radiographic results of an early minimally invasive osteosynthesis with the MIROS device. A total of 40 consecutive patients were treated for an intra-articular fracture of the calcaneus. We evaluated the clinical and radiographic outcomes after treatment of intra-articular calcaneal fractures with the MIROS hardware. Soft tissue damage was noted. The patients completed the American Orthopaedic Foot and Ankle Society survey at 12 and 24 months and underwent radiologic evaluations. A statistically significant association between the American Orthopaedic Foot and Ankle Society score and type of soft tissue lesion. A Sanders type II, III, and IV fracture was found in 15, 20, and 15 of 50 fractures, respectively. Postoperatively, restoration of the posterior facet was reached in 13 of 15, 18 of 20, and 11 of 15 with a type II, III, and IV fracture, respectively. The American Orthopaedic Foot and Ankle Society scale mean score was 85 at the final follow-up visit. No significant association was found between the score and the preoperative variables (p > .09), although patients with bilateral fractures had a significantly lower score. The MIROS device for early treatment of intra-articular calcaneus fractures resulted in excellent clinic and radiologic results. The standardized technique we have reported, with the elastic wires acting as a girder for the fractured and displace subtalar joint and the collapsed lateral calcaneal wall, has permitted early weightbearing with positive stimuli for the bone healing. The drainage effect of the percutaneous wires likely prevented compartment syndrome when applied within the first hours after the trauma.

[Criteria of the OCRA method in evaluating the structural assembly of aircrafts: preliminary data]. / Criteri applicativi del metodo OCRA nella valutazione dell'assemblaggio strutturale degli aeromobili: dati preliminari.

In the aircraft productive sector, the risk assessment of repetitive occupational activities through the OCRA method presents some major obstacles: - high number of different tasks (more than 20) carried out during the work shift. - definite identification of the number of technical actions per cycle. Risk assessment through the traditional OCRA method provides in this sector a index which varies according to the sampling of the occupational tasks, rather than reflecting the effective risk level. The study raises an OCRA-based method which is applicable in the aircraft production sector and defines the overall ergonomic load for homogeneous groups of exposed workers, based on production data specified for each aircraft model.

Iatrogenic atrial septal defects following atrial fibrillation transcatheter ablation: a relevant entity?

AIMS: The previous literature has suggested that the iatrogenic atrial septal defects (IASDs) may follow left atrial (LA) access by transseptal (TS) puncture, especially in the case of a single TS for more than one catheter. The aim of the present study is to describe the prevalence of patent foramen ovale (PFO) and IASDs in a cohort of atrial fibrillation (AF) patients undergoing redo catheter ablation (CA) procedures in a high-volume centre accessing LA by a standardized single TS puncture. METHODS AND RESULTS: Patients (n = 197) who underwent at least one redo AFCA, between 2004 and 2012, were retrospectively enroled. Transoesophageal echocardiography was performed before each procedure during which LA was accessed via a PFO, if present, or by single TS for both the mapping and ablation catheters. At baseline, PFO was detected in 43 (21.8%) patients. Clinical and echocardiographic parameters recorded did not differ within patients presenting with or without PFO. Left atrium was accessed via PFO in 39 (90.7% of those with PFO) patients during the first procedure. New-onset IASD occurred in 11 (5.6%) patients following the first procedure and in 1 (2.2%) patient following the second procedure. The clinical and echocardiographic parameters did not differ within the patients irrespective of whether IASD was reported or not. No TS-related complications occurred. CONCLUSION: In the present cohort, LA access by PFO or single TS for both the mapping and ablation catheters lead to a small risk of asymptomatic IASD, not increased by redo procedures, confirming that it represents a safe approach. No clinical and/or echocardiographic parameters seemed to predict IASD occurrence.

Very long-term results of electroanatomic-guided radiofrequency ablation of atrial arrhythmias in patients with surgically corrected atrial septal defect.

AIMS: Atrial tachycardias are common after repair of atrial septal defect (ASD). Although ablation has shown promising results in the short and mid-term follow-up, little data regarding the very long-term success exist. Our aim was to assess very long-term follow-up in patients who have undergone electroanatomic-guided radiofrequency (RF) ablation of late-onset atrial arrhythmias after ASD surgery. METHODS AND RESULTS: Forty-six consecutive patients with surgically repaired ASD were referred for atrial tachycardia ablation. Electrophysiological (EP) study and ablation procedure with the aid of an electroanatomic mapping (EAM) system were performed. Mean age was 49 ± 13 years (females 61%). The presenting arrhythmias were typical atrial flutter (48%), atypical atrial flutter (35%), and atrial tachycardia (17%). In 41% of patients, atrial fibrillation was also present. The EP study showed a right atrial macroreentrant circuit in all the patients. In 12 of 46 (26%), the circuit was localized in the cavo-tricuspid isthmus, whereas in the remaining 34 patients (74%) was atriotomy-dependent. Acute success was 100%. Clinical arrhythmia recurred in 24% of the patients. Nine patients underwent a second and two a third ablation procedure, reaching an overall efficacy of 87% (40 of 46) at a mean follow-up of 7.3 ± 3.8 years since the last procedure. With antiarrhythmic drugs the success rate increased to 96% (44 of 46). No complications occurred. CONCLUSION: In patients with surgically corrected ASD, EAM-guided RF ablation of late-onset macroreentrant atrial arrhythmias demonstrated a high success rate in a very long-term follow-up. Therefore, RF ablation could be considered early in the management of late-onset macroreentrant atrial tachycardias.

Incidence of cerebral thromboembolic events during long-term follow-up in patients treated with transcatheter ablation for atrial fibrillation.

AIMS: Net clinical benefit of long-term oral anticoagulation therapy (OAT) continuation after successful atrial fibrillation (AF) ablation is still controversial. To evaluate long-term thromboembolic (TE) and haemorrhagic events incidence according to OAT strategy used after AF transcatheter ablation. METHODS AND RESULTS: Three months after AF ablation, OAT was discontinued in patients with CHADS2 ≤ 1 if no recurrences were documented, while OAT was maintained in patients with CHADS2 ≥ 2 regardless of AF recurrences. CHA2DS2VASc and HAS-BLED scores have been retrospectively evaluated. Seven hundred and sixty-six patients were followed for a median of 60.5 months. Six (6/267 = 2.2%) and five (5/499 = 1%) TE events occurred in the ON and the OFF-OAT patients, respectively (P = 0.145), all in concomitance with the AF recurrence. CHADS2 and CHA2DS2VASc ≥ 2 were associated with high TE incidence (P = 0.047 and P = 0.020). Among patients with a CHADS2 score of 0 or 1, a CHA2DS2VASc score ≥ 2 was predictive of TE events (P = 0.014). Overall, the incidence of the TE events in patients with CHA2DS2VASc ≥ 2 was 0.6 per 100 patient-years whereas seven haemorrhagic events occurred, all of them in the ON-OAT patients (7/267 = 2.6%). CONCLUSION: Patients with AF undergoing transcatheter ablation have a lower incidence of TE events as compared with the general AF population, regardless of OAT maintenance. The unpredictable risk of AF recurrence, mandate the routine use of the CHADS2, CHA2DS2VASc, and HAS-BLED scores to guide clinical decision regarding OAT management in this peculiar setting of patients. The potential protective role of rhythm control strategy in the TE events needs to be confirmed by future large randomized trials.

Long-term efficacy and safety of two different rhythm control strategies in elderly patients with symptomatic persistent atrial fibrillation.

BACKGROUND: We prospectively compared the efficacy, safety, and quality of life (QoL) impact of catheter ablation versus antiarrhythmic drugs (AAD) in elderly patients with persistent atrial fibrillation (AF). METHODS AND RESULTS: Four hundred and twelve consecutive patients, aged ≥ 70 years, underwent ablation (Group A, 153 patients) or AAD (Group B, 259 patients). Study endpoints: treatment failure (any AF/AT lasting >30 seconds) and treatment-related adverse events (acute when ≤1 month of procedure and long term when >1 month). At a follow-up of 60 ± 17 months, 43% and 46% patients in Group B versus 58% and 76% in Group A were in sinus rhythm (SR), respectively, after one (P = 0.003) and 2 procedures (P < 0.001). Fifteen acute adverse events occurred (6.7% in Group A vs 1% in Group B, P < 0.001), mainly periprocedural cerebral thromboembolism (3.3% in Group A vs 0.7% in Group B, P = 0.058). Previous TIA/stroke resulted the only independent predictor of periprocedural cerebrovascular accidents (OR 1.2, 95%IC 1.1-1.3). At follow-up, 74 long-term adverse events occurred (7.7% in Group A vs 23.9% in Group B, P < 0.001) with Group B patients more often experiencing AAD-related adverse events (12.7% vs 2.6%, P < 0.001). Group A and absence of AF/AT recurrences significantly improved QoL scores (P < 0.001). CONCLUSIONS: In elderly persistent AF patients, catheter ablation is more effective in maintaining SR and in improving QoL than AAD but is affected by a higher risk of embolic complications, particularly in patients with previous TIA/stroke. Over time, Group A patients more likely discontinued AAD with a reduction of long-term adverse events.

[Management of postoperative arrhythmias in the tetralogy of Fallot: a literature review]. / Gestione delle aritmie cardiache dopo correzione chirurgica della tetralogia di Fallot: revisione della letteratura.

Tetralogy of Fallot (ToF) occurs in about 4 births/1000/year and represents about one tenth of all congenital heart diseases. Nowadays 86% of patients reach adulthood with corrective surgery. Before the 1980s, these patients were treated only with "surgical palliation", which consisted in the creation of a systemic to pulmonary artery shunt or a pulmonary valvulotomy, whereas after the introduction of extracorporeal circulation, corrective surgery is performed electively between 3 and 6 months of life. After repair patients during their life may develop hemodynamic lesions, including right ventricular outflow tract dysfunction, and arrhythmias which can occur in over 30% of cases. It is estimated that these patients present a risk of sudden death of 0.2%/year. Therefore, for the prevention and treatment of arrhythmic events, a periodic follow-up in specialized centres for adult congenital heart disease is mandatory, because most often arrhythmias are triggered by the presence of hemodynamic lesions, first of all pulmonary regurgitation.

Electrical cardioversion of persistent atrial fibrillation: acute and long-term results stratified according to arrhythmia duration.

BACKGROUND: Current definition of persistent atrial fibrillation (PAF) enrolls a heterogeneous population with different atrial fibrillation (AF) exposure and degree of atrial substrate. Study aims were to evaluate acute and long-term results of electrical cardioversion (ECV) and to identify temporal cutoff of previous AF exposure to reclassify PAF in subgroups with different chance of sinus rhythm (SR) maintenance. METHODS: Five hundred twenty-one patients (66% men; age 69 ± 10 years) with PAF undergoing ECV, were divided in four groups according to AF duration at the time of ECV: group A with AF ≤2 months (141 patients); group B with AF >2 and ≤4 months (176 patients); group C with AF >4 and ≤6 months (89 patients); and group D with AF >6 months and <1 year (115 patients). RESULTS: There was no difference in term of acute success among groups (98.5% vs 97.1% vs 98.9% vs 96.5%, respectively, P = 0.95). At 5-year follow-up, 198 (41%) patients were in SR: 50% in group A, 44% in group B, 42% in group C, and 25% in group D (P < 0.001). At the multivariate analysis, previous ECV (hazard ratio [HR] 1.55, P < 0.001), left atrium enlargement (HR 1.39, P = 0.013), and AF duration >6 months at time of procedure (HR 1.59, P = 0.001) independently predict ECV failure. CONCLUSION: ECV is associated with high acute success rate and low complications rate. Long-term results are strongly related with AF duration at time of ECV: a cutoff of >6 months helps in selecting patients that can take greater advantage of the procedure.

Adjunctive hypnotic communication for analgosedation in subcutaneous implantable cardioverter defibrillator implantation. A prospective single center pilot study.

BACKGROUND: Subcutaneous implantable cardioverter defibrillator (S-ICD) is a well-established therapy for sudden death prevention. Considering the painful nature of the procedure anaesthesia may be required for analgo-sedation. Hypnosis is emerging as a promising therapeutic strategy for pain control. Few data are available regarding the use of hypnosis as adjunctive technique for pain control during S-ICD implantation. METHODS: Thirty consecutive patients referred to our centre for S-ICD implantation were prospectively and alternatively allocated with 1:1 ratio in two groups: A) Standard analgo-sedation approach (Hypnosis non responder patients) B) Standard analgo-sedation approach with the addition of hypnotic communication (Hypnosis responder patients). Peri-procedural pain perception and anxiety, perceived procedural length, type and dosage of administered analgesic drugs have been measured using validate scores and compared. RESULTS: Hypnotic communication was offered to 15 patients of which was successful in 11 patients (73%). There were no statistical differences between the two study groups according to baseline characteristics. Hypnosis communication resulted in significant pain perception reduction (Group A 6,9 ± 1,6 Vs Group B 1,1 ± 0,9, p value < 0,01), peri-procedural anxiety (Group A 3,5 ± 1,6 Vs Group B 1,9 ± 0,5, p value < 0,01) and reduced perceived procedural length (Group A 58,7 ± 13,4 min Vs Group B 44,7 ± 5,5 min, p value < 0,01). Fentanyl dosage was significantly lower in Group B patients. CONCLUSIONS: Our results demonstrated a significant reduction of perceived pain, anxiety, procedural time and use of analgesic drugs in hypnosis responder patients. These results reinforce the beneficial effects of the hypnotic technique in patients undergoing S-ICD implantation.

Zero-fluoroscopy atrial fibrillation ablation in the presence of a patent foramen ovale: a multicentre experience.

INTRODUCTION: Atrial fibrillation ablation has historically been guided by fluoroscopy, with the related enhanced risk deriving from radiation. Fluoroscopy exposure may be confined to guide the transseptal puncture. Small sample size study presented a new methodology to perform a totally fluoroless atrial fibrillation ablation in the case of a patent foramen ovale (PFO). We evaluated this methodology in a large sample size of patients and a multicentre experience. METHODS AND RESULTS: Two hundred and fifty paroxysmal atrial fibrillation patients referred for first atrial fibrillation ablation with a CARTO3 electroanatomic mapping system were enrolled. In 58 out of 250 patients, a PFO allowed crossing of the interatrial septum, and a completely fluoroless ablation was performed applying the new method (Group A). In the remaining patients, a standard transseptal puncture was performed (Group B). Pulmonary vein isolation was achieved in all patients with comparable procedural and clinical outcomes at short- and long-term follow-up. CONCLUSION: The presence of a PFO may allow a completely fluoroless well tolerated and effective atrial fibrillation ablation. Probing the fossa ovalis looking for the PFO during the procedure is desirable, as it is not time-consuming and can potentially be done in every patient undergoing atrial fibrillation ablation.

Catheter Treatment of Ventricular Tachycardia: A Reference-Less Pace-Mapping Method to Identify Ablation Targets.

OBJECTIVE: A novel method is developed to identify ablation targets for the catheter treatment of ventricular tachycardia (VT). METHODS: The method is based on pace-mapping, which is a validated technique to determine the catheter ablation targets. Conventionally, it consists of stimulating the heart ventricle from various sites and comparing the resulting activation pathways to that of a clinical VT by the analysis of surface electrocardiograms (ECG). In this paper, a novel pace-mapping method is presented, which does not require a reference ECG recording of the VT. A three-dimensional correlation gradient map is reconstructed by semiautomatic analysis of ECG morphological changes within the network of pace-mapping sites. In these maps, abnormal points are identified by high correlation gradient values (i.e., corresponding to slow propagation of the electric influx, as in the core of the reentrant VT circuit). The relation between the conventional and reference-less method is described theoretically and evaluated in a retrospective study including 24 VT ablation procedures. RESULTS: The "reference-less" method was able to identify normal points with a high accuracy (negative predictive value: NPV = 97%), and to detect more abnormal points, as predicted by the theory. Correlation gradients computed by the proposed method were significantly higher in ablation zones than in other zones of the ventricle (p < 10-12), indicating excellent prediction of the ablation targets. SIGNIFICANCE: The reference-less method might either be used in complement of the conventional method or to treat patients in whom VT cannot be induced during the intervention.

Electrocardiogram Acquisition During Remote Magnetic Catheter Navigation.

Electrocardiogram (ECG) acquisition is required during catheter treatment of cardiac arrhythmias. The remote magnetic navigation technology allows the catheter to be moved automatically inside the heart chambers using large external magnets. Each change of position of the catheter requires fast motion of the magnets, therefore magnetic fluxes are created through the ECG cables, causing large distortions of the ECG signals. In this study a novel ECG sensor is proposed for reducing such distortions. The sensor uses short cables to connect the electrodes to the amplification and optical conversion circuit, using a technology similar to that used for magnetic resonance imaging. The proposed sensor was compared to the conventional 12-lead ECG device during various operation modes of the magnets. Quantitative morphological analysis of the different waves of the ECG was performed in two healthy subjects and on a conductivity phantom reproducing various cardiac pathologies. In healthy subjects the beat-to-beat correlation coefficients were improved with the proposed sensor for the PR interval (80-93% vs. 49-89%), QRS complex (93-96% vs. 74-94%), ST segment + T wave (95-98% vs. 67-99%), and whole PQRST wave (82-97% vs. 55-96%). Similar observations were made with the conductive gel in the whole PQRST wave in the pathological morphologies of the ECG for the VT (99% vs. 56-98%), AT (95% vs. 26-89%), STE (96-97% vs. 20-91%) and STD (96% vs. 28-90%). The new sensor might be used for better (uninterrupted) monitoring of the patient during catheter interventions using remote magnetic navigation. It has the potential to improve the robustness and/or duration of certain clinical procedures such as ventricular tachycardia ablation.