Search

Key Clinical Message: Effective and stable contact between the catheter tip and the tissue is crucial for both mapping and lesion formation during cardiac ablation procedures. Contact force catheter may be not only a therapeutic approach to arrhythmias, but also a tool for achieving accurate characterization of the arrhythmic substrate. Effective and stable contact between the catheter tip and the tissue is crucial for both mapping and lesion formation during cardiac ablation procedures. Contact force catheter may be not only a therapeutic approach to arrhythmias, but also a tool for achieving accurate characterization of the arrhythmic substrate [ABSTRACT FROM AUTHOR]

Background: Fluoroscopic guidance is the standard tool used in device implantation. This means that both the patient and the operator are exposed to radiation, which may sometimes be high. The possibility of single-lead permanent pacemaker implantation without fluoroscopy has already been demonstrated.Objective: The aim of our study was to investigate the feasibility and reliability of biventricular device implantation guided only by an electroanatomic navigation system.Methods: Sixty-one patients with heart failure underwent implantation of a cardiac resynchronization therapy (CRT) device with or without defibrillator (CRT-D; CRT-P). The procedure was performed with or without fluoroscopy guidance (Rx+; Rx0). In the latter case, the EnSite Velocity system was used; this system is able to reconstruct the anatomy and activation of the cardiac chambers by simultaneously collecting a "cloud" of anatomical points from multiple electrodes.Results: Lead positioning was achieved in 24 of 26 patients undergoing CRT implantation without fluoroscopy (92% success). No complications were observed during the procedure and no catheter dislodgment occurred the day after the implantation or during 1-month follow-up. Procedure time progressively decreased from 136 minutes in the first case to 59 minutes in the last one, suggesting that operators gradually gained confidence while using the new technique.Conclusion: Our study demonstrates the feasibility, efficacy, and safety of lead positioning guided only by the nonfluoroscopic EnSite Velocity mapping system without the use of fluoroscopy in CRT-P or CRT-D implantation. The benefits in terms of significantly reduced fluoroscopy exposure are associated with technical and clinical advantages. [ABSTRACT FROM AUTHOR]

Background: Radiation exposure related to conventional tachyarrhythmia radiofrequency catheter ablation (RFCA) carries small but not negligible stochastic and deterministic effects on health. These effects are cumulative and potentially more harmful in younger individuals. Nonfluoroscopic mapping systems can significantly reduce the radiological exposure and in some cases it can completely eliminate it.Objective: The aim of this study was to assess the safety, feasibility, and efficacy of a complete nonfluoroscopic approach for RFCA compared with ablation procedures performed under fluoroscopic guidance.Methods: RFCA was performed in 442 consecutive patients (mean age 58 ± 19 years). The first 145 patients (group 1) were treated only under fluoroscopic guidance, and the following 297 patients (group 2) were treated using a nonfluoroscopic electroanatomic mapping system (EnSite Velocity). RFCA was completely performed without fluoroscopy in 255 of 297 patients in group 2 (86%).Results: The acute success rate did not differ between group 1 and group 2 (97% vs 96%; P = .46), and there were no differences in either procedure time (87 ± 57 minutes vs 91 ± 52 minutes; P = .41) or complication rate. Fluoroscopic exposure in group 2 was significantly reduced in comparison with group 1 (14 ± 6 seconds vs 1159 ± 833 seconds; P < .0001).Conclusion: Compared with the conventional fluoroscopic technique, the near-zero radiation (RX) approach provides similar outcomes and may significantly reduce or eliminate ionizing radiation exposure in RFCA. These reductions are achieved without altering the duration or compromising the safety and effectiveness of the procedure. [ABSTRACT FROM AUTHOR]

Aim: Gender related differences in epidemiology, treatment, and prognosis of heart failure (HF) have been reported. We examined the sex influence in patients treated with cardiac resynchronization therapy (CRT). Methods and Results: Out of 334 consecutive HF patients (19.7% women) who underwent CRT, 195 patients reached clinical and echocardiographic evaluation at six and 12 months and were selected for analysis. A reduction in left ventricular (LV) end-diastolic volume/m2 (EDVi) and end systolic volume/m2 (ESVi) was evident in the overall population at six months (P < 0.001) and from six to 12 months (P < 0.001). Compared to men, women showed significantly greater changes in LV volumes at mid (P < 0.05) and long-term (P < 0.001) follow-up and a significantly higher LV ejection fraction (EF) (40.8 ± 12.3 vs 34.1 ± 10.1, P < 0.01) at one year. Multiple regression analysis, including several demographic and clinical parameters, revealed that female gender is independently associated with greater reduction in LV ESVi. At the 12-month follow-up, the proportion of responders (defined in terms of ESV reduction by at least 10%) was higher in women than in men (76.1% vs 59.3%, P < 0.05). Conclusions: CRT induced a gender specific LV remodeling response. [ABSTRACT FROM AUTHOR]

Aims In patients with atrial fibrillation right ventricular pacing can block antegrade conduction at pacing intervals longer than the shortest spontaneous R–R interval, causing the stabilization of ventricular rhythm. In this study the effects of pacing at two sites were compared in order to evaluate the role of conduction times in determining the stabilization of ventricular rhythm. Methods In eight patients with permanent atrial fibrillation, the ventricular rate was recorded before and during pacing at the right ventricular apex and the His bundle with different cycle lengths. Results In all patients, we obtained a reduction in spontaneous QRS complexes with respect to those anticipated at pacing rates slightly above the spontaneous mean rate, and the ventricular rhythm stabilized at pacing intervals longer than the spontaneous shortest R–R intervals. Between pacing sites we did not observe any difference in the reduction in spontaneous beats and the cycle stabilizing the rhythm. Moreover, simulation of the interaction between antegrade and retrograde impulses in a computer model confirmed that results obtained by pacing at the His bundle cannot be readily explained as a consequence of conduction delays. Conclusion This study suggests that the lag introduced by the His-Purkinje conduction cannot explain, as proposed, the stabilization of ventricular rhythm observed in patients with atrial fibrillation and right ventricular pacing. [ABSTRACT FROM PUBLISHER]

PADELETTI, L., et al.: Atrial Septal Pacing: A New Approach to Prevent Atrial Fibrillation. Atrial pacing may prevent the onset of atrial fibrillation (AF) because of: (1) prevention of the relative bradycardia that triggers paroxysmal AF; (2) prevention of the bradycardia induced dispersion of refractoriness; (3)suppression or reduction of premature atrial contractions that initiate reentry and predispose to AF; (4) preservation of AV synchrony, which might prevent switch induced changes in atrial repolarization predisposing to AF. Atrial pacing locations that decrease atrial activation and dispersion of refractoriness may be preferable in patients with a history of AF. Two different interatrial septum sites have been proposed: the Bachmann's bundle and the coronary sinus ostium. The results of two prospective randomized studies indicate that septal pacing, when compared to the traditional right atrial appendage pacing, significantly reduces : (1) paroxysmal AF recurrences and burden; and (2) progression to chronic AF. (PACE 2004; 27[Pt. II]:850–854) [ABSTRACT FROM AUTHOR]

PORCIANI, M.C., et al.: A Perspective on Atrioventricular Delay Optimization in Patients with a Dual Chamber Pacemaker. Atrioventricular delay (AVD) is critical in patients with DDD pacemakers (PM). Echo/Doppler evaluation of AVD providing the longest left ventricular filling time (FT) or the highest cardiac output (CO) is used for AVD optimization. Recently myocardial performance index (MPI) has been shown to improve by optimizing AVD. The aim was to compare the CO, FT, MPI derived optimal AVD, and to analyze systolic and diastolic performance at every optimal AVD. Twenty-five patients, 16 men 68 ± 11 years, ejection fraction ≥ 50%, with a DDD PM for third-degree AV block, without other major cardiomyopathies, underwent echo/Doppler AVD optimization. CO, FT, and MPI derived optimal AVDs were identified as the AVDs providing the highest CO, the longest FT, and the minimum MPI, respectively. Isovolumic contraction and relaxation time (ICT, IRT), ejection time (ET), ICT/ET, and IRT/ET ratios were also evaluated at every optimal AVD. CO, FT, and MPI derived optimal AVDs were significantly different (148 ± 36 ms, 116 ± 34 ms, and 127 ± 33 ms, respectively). ICT/ET was similar at CO, FT, and MPI derived optimal AVD (0.22 ± 0.10, 0.23 ± 0.11, and 0.21 ± 0.10, respectively). IRT/ET ratio was similar at FT and MPI derived optimal AVDs (0.34 ± 0.15 and 0.33 ± 0.15, respectively) and significantly shorter (P < 0.02) than at CO derived optimal AVD (0.40 ± 0.15). Different methods indicate different optimal AVDs. However analysis of systolic and diastolic performance shows that different AVDs result in similar systolic or diastolic performance. At MPI optimized AVD, a high CO combined with the most advantageous conditions of both isovolumic contraction and relaxation phases is achieved. (PACE 2004; 27:333–338) [ABSTRACT FROM AUTHOR]

Linear Ablation and Pacing Site in AF Prevention. Introduction: Right atrial linear lesions (RALL), either alone or in combination with antiarrhythmic drug therapy, may modify the substrate for maintenance of atrial fibrillation (AF). The aim of this prospective randomized study was to determine whether RALL provides additional benefit to right atrial appendage pacing (RAAP) and/or interatrial septum pacing (IASP) and drug therapy in patients with symptomatic paroxysmal AF and sinus bradycardia requiring permanent atrial pacing. Methods and Results: Sixty-four patients (33 men and 31 women, mean age 73 ± 10 years ) completed the 6-month follow-up. Patients were randomized to either RALL (n = 33) or non-right atrial linear lesions (NRALL), and then to either IASP (n = 32) or RAAP (n = 32) . Fifteen RALL patients were paced at the IAS and 18 at the RAA. Seventeen NRALL patients were paced at the IAS and 14 at the RAA. No statistical difference was observed with regard to the mean atrial tachyarrhythmia (AT) burden between NRALL (84 ± 169 min/day) and RALL patients (202 ± 219 min/day) . Mean AT burden was significantly lower in the IASP group (70 ± 150 min/day) than in RAAP group (219 ± 317 min/day; P < 0.016) . In the RALL group, the mean AT burden was 99 ± 180 min/day in the IASP patients and 288 ± 372 min/day in the RAAP patients (P < 0.046) . In the NRALL group, no statistical difference in the mean AT burden was observed between IASP patients (46 ± 117 min/day) and RAAP patients (130 ± 211 min/day) . Conclusion: The results of the present study indicate that RALL did not provide any additional therapeutic benefit to combined antiarrhythmic drug therapy and septal or nonseptal atrial pacing in patients with sinus bradycardia and paroxysmal AF. (J Cardiovasc Electrophysiol, Vol. 14, pp. 733-738, July 2003). [ABSTRACT FROM AUTHOR]

PIERAGNOLI, P.,et al.: A New Algorithm for Closed-Loop Stimulation: A Feasibility Study.Closed-loop stimulation (CLS) is a physiological system for adaptive rate pacing based on monitoring and processing of the intracardiac impedance. The “standard” CLS algorithm (SCLS) requires continuous ventricular pacing. A new, enhanced CLS algorithm (ECLS) provides rate modulation during sensed and paced ventricular depolarizations. The aim of this study was to validate ECLS and to compare its effectiveness with that of SCLS. Ten patients received Inos[sup 2+] CLS pulse generators. SCLS and ECLS were uploaded to the device and evaluated in a randomized, crossover fashion at 30 and 45 days after pacemaker implantation. At each follow-up visit, ambulatory and posture tests were performed. Heart rate (HR) during daily activity was evaluated based on 24-hour Holter recordings. During all phases of the ambulatory test, both algorithms provided physiologically appropriate rates in all patients. The proportion of sensed ventricular events was significantly higher in ECLS (93.9%) than in SCLS (0.7%). The proportion of paced ventricular events during 24 hours was substantially lower with ECLS (25.7%) than with SCLS (98.4%). Postural changes did not influence HR with either algorithm. The Holter recordings indicated prompt, safe, and effective rate modulation appropriate to patient activity. In conclusion, analysis of these clinical data demonstrated the safety and effectiveness of the ECLS algorithm. Moreover, with this algorithm the ventricle is paced only when required, which may be expected to retard battery depletion and retain the natural ventricular activation pattern whenever possible. (PACE 2003; 26[Pt. II]:229–232). [ABSTRACT FROM AUTHOR]

Aims Biventricular pacing (BVP) can improve haemodynamics in patients with dilated cardiomyopathy (DCM) and left bundle branch block by reducing interventricular delay (IVD). Since in DCM interatrial delay (IAD) and IVD frequently coexist, the aim of this study was to test the hypothesis that IVD reduction associated with IAD produces an imbalance between the programmed right atrioventricular (AV) delay and the effective AV delay on the left, and that interatrial septum pacing (IASP) combined with BVP overcomes this adverse effect. Methods and Results IAD, IVD, left and right mechanical atrioventricular delay (L-RMAVD) were measured by echo-Doppler in 29 patients with BVP: 17 patients (Group A) had the atrial lead in the right atrial appendage, 12 patients (Group B) who experienced paroxysmal atrial fibrillation had the atrial lead on the interatrial septum. In Group A, LMAVD was significantly shorter than RMAVD (172±24 vs 207±24 ms, P< 0·002), IAD was significantly longer than IVD (52±24 vs 21±18 ms, P< 0·0001). In Group B, no differences were observed between LMAVD and RMAVD (187±32 vs 185±28 ms, NS), and between IAD and IVD (11±12 vs 13±16 ms, NS). Conclusions IAD produces different left and right atrioventricular sequences in BVP. IASP combined with BVP, by resynchronizing both atria and ventricles, is able to avoid this adverse effect. [ABSTRACT FROM PUBLISHER]

Optimal management of atrial arrhythmias with dual chamber pacemakers requires proper performance of automatic mode switching (AMS). The aim of this study was to develop a reliable technique to test the AMS function by using an external electronic device capable of mimicking the occurrence of supraventricular arrhythmias (Supraventricular Arrhythmia Simulator [SAS]). The SAS delivers low voltage pulse trains (200 mV, 20 ms) through two skin electrodes. Each pulse train lasts 15 seconds and starts synchronously with a pacing pulse of the implanted pacemaker to avoid interference from the operator. The pulse train rate is set at 350, 250, and 160 beats/min to simulate AF, atrial flutter, and atrial tachycardia (AT), respectively. Thirty-five patients implanted with Vitatron pacemakers, whose AMS system has been previously validated, were enrolled. Atrial and ventricular sensing were programmed in unipolar mode at 0.5 mV and in bipolar mode at > 2 mV, respectively. All pulses from the SAS were detected by the atrial channel at an amplitude ranging from 1 to 3 mV. The test proved to be safe and reliable at rest and during exercise. AMS occurred immediately at onset or at offset of atrial arrhythmias, and no adverse interference on pacemaker function was seen from the SAS. In conclusion, the described technique and the SAS are safe and reliable for patient and pacemaker function and can be proposed as a useful method to verify proper performance of AMS function irrespective of the type of implanted devices. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate the spatial patterns of organization of fibrillation in the right atrium using bipolar recordings from a basket catheter in a population of 17 patients with persistent AF. The number of occurrences (NO) (i.e., the number of points laying on the baseline) was used as an objective measure of organization. This parameter significantly matches Wells' criteria for the classification of bipolar recordings during AF. The anatomic correspondence of the splines with eight atrial regions (namely anterior free wall, lateral free wall, posterolateral free wall, posterior free wall, posterior atrial septum, atrial septum, tricuspid valve, and anterior tricuspid valve) was assessed by fluoroscopic projections and electrogram morphology. Each region was further divided into high, mid-high, mid-low, and low segments. It was observed that individual and well-defined patterns of organization characterize the electrical activity of the right atrium in patients with persistent AF. When observed over 10 minutes, these patterns are rather stable in time. In each patient, the NO measurements were significantly different in the various right atrium regions (F < 0.0001 for all patients, Friedman test). The NO averaged over the population was significantly different among the regions (F < 0.001, Kruskal-Wallis test), owing to a common disorganized pattern observed in the tricuspid valve and anterior tricuspid valve regions. When these regions were removed from the analysis, the differences among the remaining regions were not statistically significant (F = 0.77). In conclusion, the quantitative assessment of organization in the entire right atrium showed an individual rather than common distribution. This may have implications in the choice of regions candidate for ablation. [ABSTRACT FROM AUTHOR]

Interatrial septum pacing (IASP) reduces interatrial conduction time and consequently may interfere with atrioventricular delay (AVD) optimization. We studied 14 patients with an implanted BEST Living system device able to measure peak endocardial acceleration (PEA) signal. The aims of our study were to compare the (1) optimal AVD (OAVD) in right atrial appendage pacing (RAAP) and IASP, and (2) OAVD derived by the PEA signal versus OAVD derived by Echo/Doppler evaluation of the left ventricular filling time (LVFT) and cardiac output (CO), Measurements were performed in DDD VDD modes Eight patients (group A) had RAAP and six patients (group B) had IASP. In group A, OAVD measured by LVFT, CO, and PEA was 185 ± 23 ms, 177 ± 19 ms, and 192 ± 23 ms in DDD and 147 ± 19 ms, 135 t 27 ms, and 146 ± 20 ms in VDD. respectively. OAVD measured by LVFT. CO, and PEA was significantly longer in DDD mode than in VDD (P < 0.01, P < 0.01, P < 0.001). In group B, OAVD measured by LVET, CO, and PEA was 116 ± 19 ms, 113 ± 10 ms, and 130 ± 30 ms in DDD and 106 ± 16 ms, 96 ± 15 ms, and 108 ± 26 ms in VDD, respectively. No statistical differences were observed between DDD and VDD. Significant correlations between OAVDs PEA derived and OAVDs LVFT and CO derived were observed (r = 0.71, r = 0.69, respectively). When new techniques of atrial stimulation, as IASP, are used an OAVD shorter and similar in VDD and DDD has to be considered. The BEST Living system could provide a valid method to ensure, in every moment, the exact required OAVD to maximize atrial contribution to CO. [ABSTRACT FROM AUTHOR]