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Angel Arenal

Publications and source records attributed to Angel Arenal.

16 recordsLinked to original sources
PubMed2006

Activation of inward rectifier potassium channels accelerates atrial fibrillation in humans: evidence for a reentrant mechanism.

BACKGROUND: It is unclear whether atrial fibrillation (AF) drivers in humans are focal or reentrant. To test the hypothesis that functional reentry is involved in human AF maintenance, we determined the effects of adenosine infusion on local dominant frequency (DF) at different atrial sites. By increasing inward rectifier potassium channel conductance, adenosine would increase DF of reentrant drivers but decrease it in the case of a focal mechanism. METHODS AND RESULTS: Thirty-three patients were studied during AF (21 paroxysmal, 12 persistent) using recordings from each pulmonary vein-left atrial junction (PV-LAJ), high right atrium, and coronary sinus. DFs were determined during baseline and peak adenosine effect. In paroxysmal AF, adenosine increased maximal DF at each region compared with baseline (PV-LAJ, 8.03+/-2.2 versus 5.7+/-0.8; high right atrium, 7+/-2.2 versus 5.4+/-0.7; coronary sinus, 6.6+/-1.1 versus 5.3+/-0.7 Hz; P=0.001) and increased the left-to-right DF gradient (P=0.007). In contrast, in persistent AF, adenosine increased DF only in the high right atrium (8.33+/-1.1 versus 6.8+/-1.2 Hz; P=0.004). In 4 paroxysmal AF patients, real-time DF mapping of the left atrium identified the highest DF sites near the PV-LAJ, where adenosine induced an increase in DF (6.7+/-0.29 versus 4.96+/-0.26 Hz; P=0.008). Finally, simulations demonstrate that the frequency of reentrant drivers accelerates proportionally to the adenosine-modulated inward rectifier potassium current. CONCLUSIONS: Adenosine accelerates drivers and increases frequency differently in paroxysmal compared with persistent human AF. The results strongly suggest that AF is maintained by reentrant sources, most likely located at the PV-LAJ in paroxysmal AF, whereas non-PV locations are more likely in persistent AF.

Adenosine↗
PubMed2006

First postpacing interval after tachycardia entrainment with correction for atrioventricular node delay: a simple maneuver for differential diagnosis of atrioventricular nodal reentrant tachycardias versus orthodromic reciprocating tachycardias.

BACKGROUND: The difference between the first postpacing interval (PPI) after tachycardia entrainment from the right ventricular apex and the tachycardia cycle length (TCL) can be used as an index of proximity to the circuit. OBJECTIVES: The purpose of this study was to determine whether the response to entrainment of tachycardia during ventricular stimulation with correction for AV node delay is a useful, simple maneuver for differentiating AV nodal reentrant tachycardia (AVNRT) from orthodromic reciprocating tachycardia (ORT) using a concealed accessory pathway. METHODS: The study consisted of 193 consecutive patients who underwent electrophysiologic study and ablation of regular paroxysmal supraventricular tachycardia without preexcitation during sinus rhythm. Tachycardia entrainment was attempted through trains of 5 to 15 right ventricular apex pacing pulses. The increment in AV nodal conduction time in the first PPI was subtracted from the PPI-TCL difference (corrected PPI-TCL). RESULTS: Electrophysiologic study demonstrated ORT in 84 patients and AVNRT in 109 patients. Transient entrainment was achieved in all but 12 patients. The mean corrected PPI-TCL difference was significantly shorter in 77 patients with ORT (66 +/- 27 ms) than in 104 AVNRT patients (151 +/- 28 ms; P <.0001). Patients with septal accessory pathways had shorter corrected PPI-TCL differences than patients with free-wall accessory pathways. The presence of a corrected PPI-TCL difference <110 ms identified all but one patient with ORT, and no patients with AVNRT had such a difference. CONCLUSION: The return cycle after tachycardia entrainment by right ventricular apex stimulation with correction for AV node delay is a rapid, useful maneuver for differential diagnosis of AVNRT vs ORT in patients without preexcitation. The presence of a corrected PPI-TCL <110 ms accurately identified with high reliability those patients with ORT.

Adult↗
PubMed2006

Improvement of quality of life by means of antitachy pacing: from PainFREE to the ADVANCE-D Trial.

BACKGROUND: Implantable cardioverter-defibrillators (ICD) can terminate ventricular tachyarrhythmias with shocks (painful) or antitachycardia pacing (painless). According to the results of the Pacing Fast VT Reduces Shock ThErapies Trials, antitachycardia pacing (ATP) can avoid painful shocks and also increase device longevity. The purpose of the ADVANCE-D (Atp DeliVery for PAiNless ICD ThErapy) study is to determine the most appropriate ventricular tachycardia (VT) therapy, so as to optimize painless therapy for life-threatening arrhythmias. METHODS AND RESULTS: The ADVANCE-D is a prospective, multicenter, parallel, two-arm randomized study designed to evaluate the efficacy of two different sequences of ATP therapies (burst 15 pulses, 88%, vs burst 8 pulses, 88%), during an episode of spontaneous arrhythmia classified as fast VT (FVT) in patients with a Class I or IIA indication for ICD implantation (single and dual chamber devices). The primary endpoint is to compare the efficacy of two ATP therapies for FVT episodes. The study will enroll a minimum of 900 patients within 2 years, followed-up for 12 months. The investigation is expected to be completed in 2007. CONCLUSIONS: The ADVANCE-D trial is the first large randomized clinical investigation aimed to evaluate optimal programming and efficacy of ATP.

Cardiac Pacing, Artificial↗
PubMed2005

Utility of nonfluoroscopic three-dimensional electroanatomical mapping in accessory pathways with prior unsuccessful ablation attempts.

Three-dimensional electroanatomic mapping was performed to guide radiofrequency catheter ablation in 17 patients with accessory pathways (APs) who had undergone 2.0 +/- 0.9 previous unsuccessful conventional procedures. In 14 patients, activation mapping was directed at the atrial insertion of the bypass during tachycardia (6 patients) or right ventricular pacing (7 patients) or by mapping atrial stimulus-delta-wave intervals. The ventricular insertion of the bypass was mapped and targeted for ablation in the remaining 3 patients. Successful AP ablation was obtained in all but 1 patient (94%) after a mean of 8 +/- 7 radiofrequency pulses, without recurrences during a mean follow-up of 16 +/- 15 months. On the basis of mapping results and successful ablation outcomes, the most likely causes of previous failed ablation attempts were anatomic or mapping reasons (13 patients), catheter manipulation-related problems (2 patients), and miscellaneous reasons (1 patient).

Adolescent↗
PubMed2005

Epicardial idiopathic ventricular tachycardia originating within the left main coronary artery ostium area: identification using the LocaLisa nonfluoroscopic catheter navigation system.

Idiopathic ventricular tachycardia (IVT) in patients without structural heart disease commonly arises from the right or left outflow tracts, but there remain arrhythmias that can only be ablated by an epicardial approach. We report a case of an epicardial ventricular tachycardia originating within the left main coronary artery ostium area, as identified using the LocaLisa nonfluoroscopic catheter navigation system. Due to the high risk of coronary artery thrombosis, ventricular tachycardia was successfully ablated by a transthoracic surgical approach using cryoenergy. Ventricular ectopy disappeared and ventricular tachycardia did not recur during long-term follow-up.

Adult↗
PubMed2005

[Spanish implantable cardioverter-defibrillator registry. First official report of the spanish society of cardiology working group on implantable cardioverter-defibrillators (2002-2004)].

OBJECTIVE: To report the 2002-2004 findings of the Spanish National Implantable Cardioverter-Defibrillator (ICD) Registry, established by the Spanish Society of Cardiology Working Group on Implantable Cardioverter-Defibrillators. MATERIAL AND METHOD: Data were collected prospectively after implantation using a single-page questionnaire returned to the Spanish Society of Cardiology. Participation was voluntary. RESULTS: The registry received reports on 925, 1,046 and 1414 implants, respectively, in the years 2002, 2003 and 2004. These figures represent 63%, 59% and 67.5%, respectively, of the total number of ICDs implanted. The reported implantation rates were 22, 24 and 33 per million, respectively, and the estimated total implantation rates were 35, 41 and 49, per million, respectively. The number of device replacements increased from 20% to 30% between 2002 and 2004. The majority of patients were male, their median age was 66 years, they had severe or moderate left ventricular dysfunction, and they were in functional class I or II. The most common underlying heart disease was ischemic heart disease. The main indications for an ICD were sustained monomorphic ventricular tachycardia and aborted sudden cardiac death, though the number of prophylactic indications has increased. Most ICDs were implanted in an electrophysiology laboratory by a cardiac electrophysiologist. The implantation rates of dual-chamber ICDs and ICDs with cardiac resynchronization therapy were approximately 30% and 15%, respectively. Very few complications occurred during implantation. CONCLUSIONS: The Spanish National ICD Registry contains a representative sample of ICD implantations performed in the country. The registry is one of the largest reported.

Adolescent↗
PubMed2004

Tachycardia-related channel in the scar tissue in patients with sustained monomorphic ventricular tachycardias: influence of the voltage scar definition.

BACKGROUND: Endocardial mapping before sustained monomorphic ventricular tachycardia (SMVT) induction may reduce mapping time during tachycardia and facilitate the ablation of unmappable VT. METHODS AND RESULTS: Left ventricular electroanatomic voltage maps obtained during right ventricular apex pacing in 26 patients with chronic myocardial infarction referred for VT ablation were analyzed to identify conducting channels (CCs) inside the scar tissue. A CC was defined by the presence of a corridor of consecutive electrograms differentiated by higher voltage amplitude than the surrounding area. The effect of different levels of voltage scar definition, from 0.5 to 0.1 mV, was analyzed. Twenty-three channels were identified in 20 patients. The majority of CCs were identified when the voltage scar definition was < or =0.2 mV. Electrograms with > or =2 components were recorded more frequently at the inner than at the entrance of CCs (100% versus 75%, P< or =0.01). The activation time of the latest component was longer at the inner than at the entrance of CCs (200+/-40 versus 164+/-53 ms, P< or =0.001). Pacing from these CCs gave rise to a long-stimulus QRS interval (110+/-49 ms). Radiofrequency lesion applied to CCs suppressed the inducibility in 88% of CC-related tachycardias. During a follow-up of 17+/-11 months, 23% of the patients experienced a VT recurrence. CONCLUSIONS: CCs represent areas of slow conduction that can be identified in 75% of patients with SMVT. A tiered decreasing-voltage definition of the scar is critical for CC identification.

Aged↗
PubMed2004

Acute and long-term outcome of transvenous cryoablation of midseptal and parahissian accessory pathways in patients at high risk of atrioventricular block during radiofrequency ablation.

The ability of transvenous cryothermal catheter ablation to create reversible lesions (cryomapping) and to avoid catheter dislodgment (cryoadherence) has been shown to be safe and highly effective in elimination of atrioventricular nodal reentrant tachycardia. In addition, cryoablation may be useful in the management of perinodal accessory pathways, but its efficacy and safety in patients at high risk of atrioventricular block during radiofrequency catheter ablation is unknown. This study prospectively evaluated the efficacy and safety of cryoablation in patients with midseptal and parahissian accessory pathways.

Adolescent↗
PubMed2004

Predictors of in-hospital ventricular fibrillation or torsades de pointes in patients with acute symptomatic bradycardia.

Severe bradyarrythmias remain as an important cause for hospital urgent admission and these patients can suffer potentially lethal complications (such as ventricular fibrillation [VF] and torsades de pointes [TdP]) between hospital admission and final therapy. Incidence and predictors of these tachyarrhythmias have not been well established. We retrospectively studied all consecutive patients (N = 243, age 75 +/- 10 years; 47% men) admitted to the emergency department of a general hospital between January 1998 and July 2000 for symptomatic bradyarrhythmia. Concomitant therapy included diuretics (25%), digitalis (10%), beta-blockers (10%), amiodarone (2%), and verapamil or diltiazem (8%). Syncope was the most frequent symptom at admission (54%). The most prevalent inclusion bradyarrhythmia was > or =second-degree AV block (82%). Eleven patients (4.5%) presented VF or TdP. Univariate predictors for these complications were previous amiodarone or diuretic intake, presentation as syncope, low serum potassium level, and longer QTc at admission. Multivariate analysis with logistic regression showed only therapy with diuretics and/or amiodarone and QTc at admission as significant predictors for TdP or VF development. Incidence of VF or TdP in patients admitted for symptomatic bradyarrhythmia is relatively important. A prolonged QTc interval and/or therapy with amiodarone or diuretics can predict their presentation.

Adult↗
PubMed2004

Basic assessment of paced activation sequence mapping: implications for practical use.

Some experiences support the use of atrial paced activation sequence mapping, but there is no systematic study assessing its spatial resolution, reproducibility, and influence of pacing parameters. The aim of this study was to evaluate these issues by using a 24-pole catheter positioned at the atrial aspect of the tricuspid and mitral annuli in 15 patients. Bipolar pacing was performed at two sites (right and left atria), 2 cycle lengths (300 and 500 ms) and two outputs (twice and tenfold the late diastolic threshold voltage for 2-ms pulses). The elapsed time between the atrial activation at the two dipoles adjacent to the pacing dipole (activation time [AT]) was measured during each pacing sequence. Changes in cycle length did not modify the AT. The increase in voltage slightly modified the AT (maximum -2 ms at the RA; 95% CI -3 to -1 ms) due to a greater shortening of the conduction time to the dipole located next to the anode. The 95% limits of the intraobserver and interobserver agreements in the AT measurement were -2 to 3 ms and -3 to 3 ms, respectively. The spatial resolution was studied in ten patients by measuring the AT during pacing from each dipole of a 20-pole catheter with a 1-3-1 mm interelectrode distance. The mean AT change was 10 +/- 4 ms per 6 mm of pacing site displacement (95% CI 8-11 ms, range 2.5-20 ms). In conclusion, paced atrial activation sequence analysis is reproducible, accurate, and relatively independent of pacing parameters.

Cardiac Pacing, Artificial↗
PubMed2004

[Non-fluoroscopic electroanatomical mapping (CARTO system) in the ablation of atrial tachycardias].

INTRODUCTION AND OBJECTIVES: The recent introduction of navigation systems has made substantial improvements in cardiac electrophysiological mapping. We present our experience with non-fluoroscopic electroanatomical mapping in patients with atrial tachycardias. PATIENTS AND METHOD: We studied 24 consecutive patients with atrial tachycardias (10 of whom had undergone previous radiofrequency ablation which failed). In all patients we performed electroanatomical mapping of the atria with the CARTO system, which combines electrophysiological and spatial information and allows visualization of atrial activation in a three-dimensional anatomical reconstruction of the atrial cavity. Mapping was performed during tachycardia (22 patients) or in sinus rhythm (2 patients), using a left atrial approach in 12 patients. Cooled-tip ablation was performed in 3 patients. RESULTS: Three-dimensional mapping distinguished clearly and rapidly between reentrant (9 patients) and focal mechanisms (15 patients). Radiofrequency catheter ablation was aimed at the critical isthmus of conduction (voltage maps) in patients with macroreentrant tachycardias. For focal tachycardias the catheter was re-navigated within the target area (activation maps) to the earliest focus of ectopic impulses. Acute success was obtained in 19 patients (79.2%), with early recurrence in 2 of them. Fluoroscopy time was 60 (21 min). CONCLUSIONS: Visualization of atrial activation in a three-dimensional reconstruction of the atria with the CARTO electroanatomical mapping system facilitated the integration of electrophysiological and anatomical information in patients with atrial tachycardias. This technique is potentially helpful in ensuring successful treatment of the substrate of tachycardia in this selected group of patients.

Adolescent↗
PubMed2003

Ablation of electrograms with an isolated, delayed component as treatment of unmappable monomorphic ventricular tachycardias in patients with structural heart disease.

OBJECTIVES: We sought to evaluate the feasibility of identifying and ablating the substrate of unmappable ventricular tachycardia (VT). BACKGROUND: Noninducible and nonstable VT cannot be ablated by the conventional approach. METHODS: We studied 24 patients with documented monomorphic VT. Twenty-one patients had ischemic cardiomyopathy, two had nonischemic cardiomyopathy, and one had tetralogy of Fallot. Twelve patients had an implantable cardioverter-defibrillator. Conventional activation mapping was not possible in 18 patients: at least 1 of the clinical VTs or the clinical VT was not inducible in 12 patients, and VT was not tolerated in 6 patients. This group had experienced between 1 and 106 VT episodes in the month before the ablation procedure. Endocardial electroanatomic activation maps (Carto System) during sinus rhythm (SR) and right ventricular apex (RVA) pacing were obtained to define areas for which an electrogram displayed isolated, delayed components (E-IDC). These electrograms were characterized by double or multiple components separated by >/=50 ms. RESULTS: One area of E-IDC was recorded in 20 patients, and 2 or more were recorded in 4 patients. In 23 patients, these areas were detected during RVA pacing; in only 14 during SR. An E-IDC area related to the clinical VT was identified in each patient. Ablation guided by E-IDC suppressed all but one clinical VT whose inducibility suppression was tested. During a follow-up period of 9 +/- 4 months, three patients had recurrences of the ablated VT and two of a different VT. CONCLUSIONS: Electrograms with IDCs related to clinical VT can be identified in the majority of patients during RVA pacing. Radiofrequency ablation of E-IDC seems effective in controlling unmappable VT.

Adult↗
PubMed2003

[Successful ablation of an automatic rhythm originating from his bundle].

Automatic junctional tachycardias are rare supraventricular tachyarrhythmias observed mainly in infants and children. This arrhythmia has a high mortality rate. We report the case of a 22-month-old infant in which the electrophysiological study disclosed an incessant junctional tachycardia originating from an automatic focus located in the His bundle region. Radiofrequency pulse delivery to the His bundle with controlled progressive heating of this region resulted in a definitive ablation of the ectopic focus without complications.

Bundle of His↗
PubMed2002

Irrigated tip catheter ablation in right posteroseptal accessory pathways resistant to conventional ablation.

Although RF ablation is an effective treatment of arrhythmias due to atrioventricular accessory pathways, there are cases refractory to conventional catheter ablation. Irrigated tip catheter ablation causes larger and especially deeper lesions than conventional ablation. This article discusses using irrigated tip catheter ablation in cases of right posteroseptal accessory pathways resistant to conventional ablation. Four consecutive patients with no structural heart disease and symptomatic arrhythmias related to right posteroseptal accessory pathways underwent irrigated tip catheter ablation. Conventional RF ablation had been unsuccessful in at least two procedures at more than one center (in three patients at the authors' center). The irrigated tip catheter (Chilli, Cardiac Pathways Corporation) uses a cooling system that is a closed circuit with a saline solution circulating at 0.6 mL/s. Temperature, power, and impedance were monitored during the RF applications. The procedure was successful in all four cases with no complications. In three of them, only one or two applications were necessary. Patients showed no recurrent arrhythmia during several months of follow-up. The results of the present study suggest that RF ablation using an irrigated tip catheter can be useful (and seems to be safe) for the treatment of some right posteroseptal accessory pathways resistant to conventional ablation.

Adult↗
PubMed2002

Usefulness of paced activation sequence mapping in catheter ablation of accessory pathways.

INTRODUCTION: Radiofrequency (RF) ablation of accessory pathways (APs) is often a time-consuming procedure, mainly because conventional criteria have modest accuracy. Thus, additional mapping criteria are desirable. Our hypothesis was that comparison of paced atrial activation sequences with that obtained during orthodromic AV reentrant tachycardia might be useful for locating the atrial insertion of single APs. METHODS AND RESULTS: The study included 15 patients with a single AP referred for ablation. Analysis of the atrial activation sequence was simplified by measuring the activation time (AT) that elapsed between two atrial reference points placed next to the AV annulus on either side of the area containing the AP. Ablation was guided by conventional criteria. Before each RF delivery, a short pacing train was delivered from the ablation catheter and, after verification of atrial capture, the AT was compared with the AT obtained during orthodromic tachycardia. Fifty sites of RF delivery were appropriate for analysis. The multivariate model with the highest predictive power included a deviation of AT between pacing and tachycardia < or = 5 msec (P < 0.001), a local AV ratio > or = 1 (P = 0.04), and stability of the local electrogram (P = 0.05). The combination of all these criteria predicted a successful application with high sensitivity, specificity, and positive predictive value (92%, 86%, and 71% respectively). To validate the method prospectively, 10 additional consecutive patients underwent an AP ablation procedure guided by these criteria. CONCLUSION: This technique seems to be highly accurate in selecting the atrial site for RF ablation of single APs.

Accessory Nerve↗