An annotation-independent algorithm based on electrogram characteristics to guide the identification of ventricular tachycardia isthmuses in patients with structural heart disease.

Background: Criteria such as electrograms voltage or late potentials have been largely utilized in the past to help identify areas of substrate maps that are within the ventricular tachycardia (VT) isthmus; yet their specificity and positive predictive value are quite low. The Lumipoint fractionation tool of the Rhythmia system illuminates regions with fractionated electrograms irrespective of their timing and annotation. We aimed to ascertain whether the use of this tool can rapidly identify areas within VT isthmuses from substrate maps.

One-year outcomes in patients undergoing very high-power short-duration ablation for atrial fibrillation.

Background: The very high-power short-duration (vHPSD) temperature-controlled ablation (vHPSD) improves the efficiency of pulmonary vein isolation (PVI) procedures. We evaluated the procedural and 12-months outcomes in atrial fibrillation (AF) patients undergoing PVI by means of vHPSD ablation. In patients with AF or atrial tachyarrythmia (AT) recurrence undergoing a redo procedure the durability of the PVI was investigated.

[Cardiac resynchronization therapy: mortality, rehospitalization, and procedure-related complications. A three-year single-center observational study within the Italian Health System].

Background: The aim of this study was to evaluate whether the benefit of cardiac resynchronization therapy with an implantable defibrillator (CRT-D) may differ among classes of indications to device therapy.

Methods: All-cause mortality, first hospitalization for non-fatal heart failure, stable improvement of NYHA functional class (responders), and implant-related complications were evaluated retrospectively in 103 patients selected among those (n = 133) who received consecutively CRT-D between 2006 and 2009. Patients were divided into three groups: group IA (n = 65) included patients receiving CRT-D for a class IA indication; group IIa (n = 26) included patients with atrial fibrillation and QRS ≥ 130 ms receiving CRT-D for a class IA indication; nonconventional group (NC) (n = 12) included patients with an indication to defibrillator implantation extended to CRT-D because of NYHA class III-IV and echocardiographic evidence of electromechanical dyssynchrony.

Noninvasive assessment of left ventricular contractility by pacemaker stress echocardiography.

Background: Estimating contractility of the left ventricle with noninvasive techniques is an important yet elusive goal. Positive inotropic interventions are mirrored by smaller end-systolic volumes and higher end-systolic pressures. An increased heart rate progressively increases the force of ventricular contraction (Bowditch treppe or staircase phenomenon).

Biventricular pacing via a persistent left superior vena cava: report of four cases.

Persistence of left superior vena cava (LSVC) is an uncommon finding during pacemaker implantation, which may be particularly relevant in performing LV transvenous pacing. Rarely, it is further complicated by the presence of atresia of the coronary sinus ostium (CSO). This article reports the authors experience with biventricular pacing (Biv-P) in this unusual clinical setting.

Programmed electrical stimulation in Brugada syndrome: how reproducible are the results?

Introduction: Inducibility of ventricular arrhythmias at programmed electrical stimulation (PES) ranges between 50% and 80% of patients with Brugada syndrome. However, the variety of PES protocols and the lack of data relative to a control group or to ventricular arrhythmia reproducibility contribute to a still undefined interpretation of PES outcome in Brugada syndrome.

Methods And Results: Twenty-one patients with Brugada syndrome (18 men and 3 women; mean age 34 years; 9/21 symptomatic; 8/21 with SCN5A gene mutation) underwent a PES protocol from two right ventricular sites.

Clinical and molecular characterization of patients with catecholaminergic polymorphic ventricular tachycardia.

Background: Mutations in the cardiac ryanodine receptor gene (RyR2) underlie catecholaminergic polymorphic ventricular tachycardia (CPVT), an inherited arrhythmogenic disease occurring in the structurally intact heart. The proportion of patients with CPVT carrying RyR2 mutations is unknown, and the clinical features of RyR2-CPVT as compared with nongenotyped CPVT are undefined.

Methods And Results: Patients with documented polymorphic ventricular arrhythmias occurring during physical or emotional stress with a normal heart entered the study.

How to test mode switching in pacemakers implanted in patients: the MOST study.

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.

Inferior vena cava loop of the implantable cardioverter defibrillator endocardial lead: a possible solution of the growth problem in pediatric implantation.

The ICD is an important treatment option in adults and children with life-threatening tachyarrhythmias. The possibility of lead displacement caused by growth and the lack of dedicated leads and devices poses special problems in pediatric ICD implantation. We describe our experience in three children in whom we left a redundant lead loop within the inferior vena cava (IVC) is allow for further growth.

Long-term follow-up after atrioventricular nodal ablation and pacing: low incidence of sudden cardiac death.

Sudden cardiac death (SCD) has been reported in patients with drug refractory AF who underwent AV nodal ablation and pacing. However, whether SCD in these patients is related to the underlying heart disease or to the ablating and pacing procedure remains uncertain. Between May 1987 and January 1997, AV nodal ablation was performed in 585 patients (mean age 66 +/- 11 years) with drug-resistant, paroxysmal (n = 308) or chronic (n = 277) AF in 12 Italian centers.

Noncontact system-guided simplified right atrial linear lesions using radiofrequency transcatheter ablation for treatment of refractory atrial fibrillation.

This article describes our experience with a staged "hybrid" approach to the treatment of drug resistant AF, in which the completeness of a single linear lesion in the RA was verified with a noncontact mapping system. Inferior vena cava-tricuspid annulus ablation was performed and followed by the creation of a single intercaval lesion. The study population consisted of 24 patients with a 3.

Determinants of efficacy of atrial pacing in preventing atrial fibrillation recurrences.

Introduction: Several studies have shown that single or dual site atrial pacing is effective in reducing the frequency of recurrent atrial fibrillation (AF) in selected patients. However, it is still unclear what the best predictors are of long-term efficacy of atrial pacing.

Methods And Results: Forty-seven patients with paroxysmal AF requiring demand pacing underwent electrophysiologic study and dual chamber pacemaker implant.

Feasibility and safety of two French electrode catheters in the performance of electrophysiological studies.

Unlabelled: The aim of this study was to analyze prospectively the feasibility and safety of using 2 Fr versus 6 Fr standard electrode catheters for diagnostic electrophysiological study.

Methods: Two hundred and five consecutive patients were randomized to receive the 6 Fr approach (3 quadripolar, 6 Fr, electrode catheters inserted through the left or right femoral vein and placed in the high right atrium, right ventricular apex, and His bundle area) or the 2 Fr approach (3 quadripolar, 2 Fr, electrode catheters inserted through a single, 7 Fr, triple lumen, guiding catheter and positioned at the same sites as the 6 Fr approach).

Results: Introduction time was shorter in the 2 Fr group (133.

Radiofrequency modification of the atrioventricular node in patients with chronic atrial fibrillation: comparison between anterior and posterior approaches.

Introduction: We compared, in a prospective and randomized fashion with a cross-over design, the anterior and posterior approaches to radiofrequency (RF) modification of the AV node in patients with chronic atrial fibrillation.

Methods And Results: Thirty-three patients were randomized to receive first an anterior (group I) or posterior (group II) approach for RF modification of AV nodal conduction. Patients who did not fill the endpoint ventricular rate (< 90 beats/min) were crossed over to the alternative approach.

Alterations in ultrasonic backscatter during exercise-induced myocardial ischemia in humans.

Background: Experimentally induced myocardial ischemia in animals causes tissue modifications that alter characteristics of the ultrasonic beam backscattered from the myocardial muscle. Alterations of backscatter parameters have been evidenced in human subjects with acute or remote myocardial infarction and during ischemia induced by angioplasty balloon occlusion or pharmacological stimuli. The effects of transient effort ischemia in humans have not been reported.

Protective effect of beta-blockade on dipyridamole-induced myocardial ischaemia. Role of heart rate.

This study was designed to investigate the effect of heart rate changes on dipyridamole echocardiographic tests in patients with coronary artery disease treated with propranolol. We prospectively studied 12 patients (8 men and 4 women; mean age 56.5 +/- 8.

Deceptive surgical results in three siblings with familial Wolff-Parkinson-White syndrome.

Three siblings with familial Wolff-Parkinson-White syndrome and two instances of sudden death are described. In all of them, multiple accessory pathways with a very short anterograde refractory period and rapid ventricular responses during atrial fibrillation had been documented, thus surgical ablation of the bypass tracts had been performed. Although abolition of the accessory pathway conduction had been demonstrated post-operatively, an electrophysiologic evaluation performed after 2-8 years showed resumption of conduction over the anomalous connections, with life-threatening arrhythmias during induced fast atrial rhythms.

Catheter-mediated electrical ablation: the relation between current and pulse width on voltage breakdown and shock-wave generation.

Voltage waveform breakdown is characteristic of barotraumatic shock-wave generation during electrical catheter ablation of cardiac arrhythmias. The purpose of this investigation was to avoid barotrauma by defining, in vitro, the limits of pulse amplitude and pulse width for rectangular constant-current pulses that do not result in voltage breakdown and subsequently to determine what pulsing frequency is safe for use when high-energy trains of pulses are used. Electric pulses were delivered with a variable waveform modulator with a wide dynamic range and bandwidth capable of delivering pulses of 30-10,000-mu sec duration with amplitudes of up to 25 A.

The automatic implantable cardioverter/defibrillator: transesophageal atrial pacing discloses the potential for erroneous discharges.

We report the occurrence of erroneous discharge from an implanted automatic cardioverter/defibrillator during transesophageal atrial pacing. Transesophageal pacing was performed as part of a study protocol on the inducibility of ventricular tachycardia from the atrium in patients with ischemic heart disease. At an induced heart rate of 166 beats per minute (a value just above the cut-off rate of the device), the cardioverter/defibrillator was triggered.

Developments, complications and limitations of catheter-mediated electrical ablation of posterior accessory atrioventricular pathways.

Nineteen patients with posterior accessory pathways and disabling, refractory arrhythmias, underwent catheter ablation using standard defibrillator pulses at energy settings of 150 to 400 J. Accessory pathway ablation was successful in 13 of 19 (68%). Effective catheter ablation correlated with local ventriculoatrial (VA) intervals determined from the coronary sinus catheter at the site of earliest retrograde atrial activation during orthodromic reciprocating tachycardia.

Catheter-mediated electrical ablation: the relation between current and pulse width on voltage breakdown and shock-wave generation.

Barotrauma from arc induced shock waves may result in dangerous sequelae during ablation of arrhythmogenic foci. In this report, maximum pulse amplitude and pulse width determinations were made to assess avoidance of shock-wave generation using rectangular constant current pulses. Energy delivery appears to be optimal between 80-100 microseconds.

Double tachycardia following surgery for recurrent ventricular arrhythmias.

Simultaneous accelerated "junctional" rhythm and atrial flutter were observed postoperatively in a patient who had undergone electrophysiologic surgery for recurrent ventricular fibrillation. Digitalis toxicity was excluded, based on the low serum level of the drug and on the recurrence of the tachycardia after withdrawal of digitalis. While atrial flutter probably represented a postoperative recurrence of a clinically occurring arrhythmia, the accelerated "junctional" rhythm at unusually fast rates most likely developed as a consequence of a cryolesion applied to the ventricular septum as part of the surgical treatment.