Biomedical subjects

F Gaita

Publications and source records attributed to F Gaita.

At least 19 recordsLinked to original sources

PubMed2001

Different patterns of atrial activation in idiopathic atrial fibrillation: simultaneous multisite atrial mapping in patients with paroxysmal and chronic atrial fibrillation.

OBJECTIVES: We aimed to evaluate: 1) the behavior of electrical activity simultaneously in different atrial regions during atrial fibrillation (AF); 2) the difference of atrial activation between paroxysmal and chronic AF; 3) the atrial refractoriness dispersion; and 4) the correlation between the effective refractory periods (ERPs) and the FF intervals. BACKGROUND: Little data exist on the electrophysiologic characteristics of the different atrial regions in patients with AF. A more detailed knowledge of the electrical activity during AF may provide further insights to improve treatment of AF. METHODS: Right and left atria were extensively mapped in 30 patients with idiopathic AF (18 paroxysmal and 12 chronic). In different atrial locations, we analyzed 1) the FF interval duration; and 2) the grade of organization and, in case of organized electrical activity, the direction of atrial activation. Furthermore, in patients with paroxysmal AF, we determined the atrial ERP, evaluated the ERP dispersion and assessed the presence of a correlation between the ERPs and the FF intervals. RESULTS: In patients with chronic AF, we observed a shortening of the FF intervals and a greater prevalence of disorganized activity in all the atrial sites examined. In patients with paroxysmal AF, a significant dispersion of refractoriness was observed. The right lateral wall showed longer FF intervals and more organized atrial activity and, unexpectedly, the shortest mean ERPs. In contrast, the septal area showed shorter FF intervals, greater disorganization and the longest mean ERPs. CONCLUSIONS: Electrical activity during AF showed a significant spatial inhomogeneity, which was more evident in patients with paroxysmal AF. The mean FF intervals did not correlate with the mean ERPs.

Adult↗

PubMed2001

Long-term follow-up of right ventricular monomorphic extrasystoles.

OBJECTIVES: The purpose of this study was to verify in a long-term follow-up whether frequent monomorphic right ventricle extrasystoles may progress to arrhythmogenic right ventricular dysplasia (ARVD). BACKGROUND: Frequent monomorphic right ventricle extrasystoles are generally considered benign. However, in patients with this pattern, cardiac magnetic resonance (MR) has recently shown anatomical and functional abnormalities of the right ventricle. METHODS: Sixty-one patients who had been classified by noninvasive examinations as having frequent idiopathic right ventricle ectopy were contacted after 15 +/- 2 years (12 to 20) and submitted to clinical examination, electrocardiogram (ECG), Holter monitoring, stress test, signal averaged ECG, echocardiography and, in 11 patients, cardiac MR. The primary end point was to ascertain the presence of cases of sudden death or progression to ARVD. RESULTS: At the end of the follow-up, 55 patients were alive; six died, none of sudden death; eight stated to be well but refused further examinations. The 47 patients examined had normal ECG; in 24 patients (51%), extrasystoles were no longer present at Holter monitoring; late potentials were present in up to 15% of the patients; the right ventricle was normal at echocardiography. In 8 of 11 patients (73%), cardiac MR showed focal fatty replacement and other abnormalities of the right ventricle. CONCLUSIONS: In this long-term follow-up study, no patient died of sudden death nor developed ARVD; two-thirds of the patients were asymptomatic, and, in half of the patients, ectopy had disappeared. Focal fatty replacement in the right ventricle was present in most.

Adolescent↗

PubMed2001

Accessory pathway potential recording in a case of permanent junctional reciprocating tachycardia with decremental conduction localized on the atrial site.

Permanent junctional reciprocating tachycardia (PJRT) is an uncommon form of atrioventricular reentrant tachycardia due to the presence of an accessory pathway characterized by slow and decremental retrograde conduction. We report a case of PJRT where we demonstrated the possibility of recording a distinct accessory pathway potential. Decremental retrograde conduction was evident using ventricular extrastimuli and it was also adenosine-sensitive. Delivering ventricular extrastimuli a prolongation of the accessory pathway potential-atrium interval was seen demonstrating that decremental conduction was located at the atrial insertion of the pathway. The accessory pathway was successfully ablated using the potential as the target of radiofrequency delivery. These electrophysiological findings seem to support the hypothesis that a nodal-like structure may be responsible for this arrhythmia.

Catheter Ablation↗

PubMed2001

Comparison of defibrillation thresholds using monodirectional electrical vector versus bidirectional electrical vector.

BACKGROUND: Currently, two main lead configurations are used for implantable cardioverter-defibrillators (ICD). One generates a monodirectional electrical vector by using the can surface as an active part (hot can) together with a right ventricular defibrillation coil. The other one (TRIAD) produces a bidirectional electrical vector by adding a proximal defibrillation electrode on the same lead. The purpose of this prospective study was to determine whether there is a difference between these configurations in terms of the acute defibrillation threshold (DFT). The secondary objective was to evaluate the possible sequential effect of successive arrhythmia induction and defibrillation shocks on the final DFT value. METHODS: In 44 patients (37 males, 7 females, mean age 59.18 +/- 12.05 years; mean ejection fraction 35.21 +/- 11.69%), a Hot Can Ventak family ICD (Guidant, St. Paul, MN, USA) was implanted in a left pectoral pocket. During the implant procedure, step-down to failure DFT testing was performed twice in each patient using the two different above-mentioned configurations: the bidirectional and the monodirectional. The first configuration to be tested was determined by a 1:1 randomization by center. RESULTS: The step-down DFT protocol was followed in 35 patients. The average DFT was 8.6 +/- 4.0 J for TRIAD and 10.4 +/- 4.3 J for the monodirectional (p = 0.009) lead configuration; this represents a 16.3% decrease in the DFT using a bidirectional configuration. Furthermore, no relationship between the final DFT and the number of ventricular fibrillation inductions and shocks received was observed, confirming the secondary objective. CONCLUSIONS: Compared to the monodirectional electrical vector, the bidirectional electrical vector is clearly more beneficial for the patient.

Adult↗

PubMed2000

Should stimulation therapy for congestive heart failure be combined with defibrillation backup?

Biventricular pacing has been proposed to resynchronize ventricular contraction in patients with congestive heart failure (CHF) and interventricular conduction delay. However, the sudden death rate is still high despite the improvement in cardiac performance. Devices combining biventricular pacing with implantable cardioverter defibrillator (ICD) backup are now under clinical investigation to demonstrate whether they can decrease sudden death. From the first implant of an ICD with biventricular transvenous pacing on August 1998 to April 2000, 96 patients underwent such implants: 67 (70%) received pacemakers alone and 29 (30%), who had class I ICD indications, received combined pacemaker/ICD systems. During a mean follow-up of 283 +/- 170 days, 13 (14%) patients died: 5 of 29 (17%) in the ICD group and 8 of 67 (12%) in the pacemaker group. A total of 15 patients (52%) had ICD shocks and 6 patients (21%) had 113 episodes of ventricular tachyarrhythmias, of which 96 (85%) were converted to sinus rhythm with antitachypacing. The echocardiograms showed a narrowing of the delay between the onset of right and left ventricular outflow from 40 +/- 37 msec to 17 +/- 16 msec (p = 0.03) and a reduction of the mitral regurgitation area from 7 +/- 3.8 cm2 to 5 +/- 4 cm2 (p = 0.04) at 3 months. Functional class improved from 2.8 +/- 0.7 to 1.6 +/- 0.5 (p <0.001) 3 months after implant. Thus, ischemic patients with reduced left ventricular ejection fraction and ventricular tachyarrhythmias seem good candidates for biventricular pacing with ICD backup. The sudden death risk for those with idiopathic dilated cardiomyopathy, however, is difficult to stratify, and the choice of ICD backup has to be considered on the basis of patient safety, as well as of costs.

Aged↗

PubMed2000

Limited posterior left atrial cryoablation in patients with chronic atrial fibrillation undergoing valvular heart sugery.

OBJECTIVES: We sought to evaluate whether a limited surgical cryoablation of the posterior region of the left atrium was safe and effective in the cure of atrial fibrillation (AF) in patients with associated valvular heart disease. BACKGROUND: Extensive surgical ablation of AF is a complex and risky procedure. The posterior region of the left atrium seems to be important in the initiation and maintenance of AF. METHODS: In 32 patients with chronic AF who underwent heart valve surgery, linear cryolesions connecting the four pulmonary veins and the posterior mitral annulus were performed. Eighteen patients with AF who underwent valvular surgery but refused cryoablation were considered as the control group. RESULTS: Sinus rhythm (SR) was restored in 25 (78%) of 32 patients immediately after the operation. The cryoablation procedure required 20 +/- 4 min. There were no intraoperative and perioperative complications. During the hospital period, one patient died of septicemia. Thirty-one patients reached a minimum of nine months of follow-up. Two deaths occurred but were unrelated to the procedure. Twenty (69%) of 29 patients remained in SR with cryoablation alone, and 26 (90%) of 29 patients with cryoablation, drugs and radiofrequency ablation. Three (10%) of 29 patients remained in chronic AF. Right and left atrial contractility was evident in 24 (92%) of 26 patients in SR. In control group, two deaths occurred, and SR was present in only four (25%) of 16 patients. CONCLUSIONS: Linear cryoablation with lesions connecting the four pulmonary veins and the mitral annulus is effective in restoration and maintenance of SR in patients with heart valve disease and chronic AF. Limited left atrial cryoablation may represent a valid alternative to the maze procedure, reducing myocardial ischemic time and risk of bleeding.

Aged↗

PubMed2000

Adipose replacement and wall motion abnormalities in right ventricle arrhythmias: evaluation by MR imaging. Retrospective evaluation on 124 patients.

We reevaluated the magnetic resonance (MR) examinations of 38 healthy volunteers (control group, CG) and of 124 patients with RV arrhythmia with left bundle branch block (LBBB) morphology: 45 with episodes of RV sustained tachycardia and of polymorphic RV premature beats (RVST-PPB group); 36 with only RV outflow tract sustained or not sustained tachycardia (RVOTT group); 43 with RV monomorphic premature beats (RVMPB group). All the examinations were reevaluated in a blinded fashion for detecting myocardial adipose replacement (AR) and wall bulges or aneurysms. In RVST-PPB patients, no AR was observed in 9%; 1 RV region involvement, 0%; 2 regions, 4%; > or = 3 regions, 87%; left ventricle (LV), 15%. RVOTT patients: 28%, 53%, 14%, 5%, and 0% [corrected], respectively. RVMPB patients: 33%, 46%, 19%, 2%, and 0% [corrected], respectively. In CG, AR was observed in 11% (in RV outflow tract), RV bulges were detected in 75% [corrected] of RVST-PPB, 39% of RVOTT, and 14% of RVMPB patients, none of the CG; RV aneurysms in 33% of RVST-PPB patients, none of RVOTT patients, RVMBP patients, and CG. A significant difference among groups for RV and LV AR as well as RV bulges and aneurysms was found (p < 0.0001). In the direct comparisons, significant differences were found for: disease duration (RVST-PPB vs. RVMPB, p = 0.0396); RV AR (all the patients groups vs. CG, RVST-PPB vs. RVOTT or RVMPB, p < 0.0001); RV aneurysms (RVST-PPB vs. CG, RVST-PPB vs. RVOTT or RVMPB, p < 0.0002); bulges (all comparisons, p < 0.0174). AR is confirmed as a structural substrate in RV arrhythmias. Number and extension of MR abnormalities are correlated to different degrees of RV arrhythmias.

Adolescent↗

PubMed2000

Impact of biventricular pacing on mortality in a randomized crossover study of patients with heart failure and ventricular arrhythmias.

Biventricular (BV) pacing is under clinical investigation for the treatment of heart failure. Its impact on mortality is unknown. Patients with heart failure and ventricular tachyarrhythmias received an implantable cardioverter defibrillator with BV pacing capability. Patients were randomized 1:1 to BV pacing or no pacing, then crossed over to the alternate mode after 3 months. All-cause mortality was measured in each arm up to the point of crossover. Fifteen of 222 patients died between implant and crossover. Five patients died while programmed to BV pacing and 19 died while programmed to no pacing. Survival in the BV pacing arm was 93 +/- 4% versus 86 +/- 6% in the no pacing arm (P = 0.18). In a patient population with symptomatic heart failure and ventricular arrhythmias, BV pacing does not appear to be associated with excess mortality. Larger and longer studies will be needed to determine if BV pacing confers a survival benefit.

Aged↗

PubMed2000

Performance of a new steroid-eluting coronary sinus lead designed for left ventricular pacing.

The Ventak CHF/CONTAK CD Biventricular Pacing Study is a prospective randomized trial to examine the safety and efficacy of biventricular (BV) pacing in patients with standard indications for an ICD, symptomatic heart failure, a LVEF < or = 0.35, and a QRS > or = 120 ms. Patients underwent implantation of a BV pacing and sensing system with backup defibrillation capability, which includes a steroid-eluting coronary venous lead that is advanced into the coronary venous vasculature by over-the-wire techniques. LV pacing threshold, BV impedance, and BV R wave amplitude were measured in 58 consecutive patients. Using a percutaneous over-the-wire insertion technique, steroid-eluting coronary venous leads were associated with satisfactory mean LV pacing threshold, BV impedance, and BV R wave amplitude acutely up to 4 months after implantation. Pacing threshold stabilized 2 weeks after lead implantation and sensing threshold remained stable from the time of implant.

Cardiac Surgical Procedures↗

PubMed2000

Efficacy of biventricular sensing and treatment of ventricular arrhythmias.

While much is known concerning the hemodynamic effects of biventricular (BV) pacing, little has been reported concerning the efficacy of BV sensing and pacing in the detection and treatment of ventricular tachyarrhythmias. Two hundred nineteen heart failure (HF) patients with VT or VF and a QRS > or = 120 ms during sinus rhythm received an ICD capable of BV pacing and sensing. Detection times of induced VF and success rates for terminating induced VT were measured. The ICD system used a left ventricular epicardial lead implanted via thoracotomy (52 patients) or a specially designed percutaneous, over-the-wire lead inserted in the coronary venous system. VF detection times and VT termination rates by antitachycardia pacing (ATP) were compared with those measured in a population of recipients of ICD using a RV lead alone. Median induced VF detection times were comparable (2.0-s BV vs 1.8-s RV). Termination of induced VT on the first attempt was comparable with BV pacing (87.4%) versus RV pacing (89.6%). The time to detect induced VF was not different with ICDs using BV sensing versus conventional ICDs using RV sensing alone. Similarly, the rates of successful termination of induced VT by ATP with BV or RV pacing were comparable.

Cardiac Pacing, Artificial↗

PubMed2000

Typical atrial flutter ablation: conduction across the posterior region of the inferior vena cava orifice may mimic unidirectional isthmus block.

INTRODUCTION: The aim of this study was to map the low right atrium before and after radiofrequency ablation of the inferior vena cava-tricuspid annulus (IVC-TA) isthmus in patients with typical atrial flutter (AFI) to better understand the electrophysiologic meaning of incomplete or unidirectional block following the ablation procedure and its relationship with AFI recurrence. METHODS AND RESULTS: We performed atrial mapping in 12 patients using a "basket" catheter in the IVC orifice, Halo catheter in the right atrium, and multipolar catheters in the coronary sinus (CS) and His region. In patients in sinus rhythm, atrial activation was analyzed during pacing from the CS and low lateral right atrium (LLRA) before and after ablation. Atrial activation propagated across the isthmus and posterior region of the IVC orifice simultaneously before ablation. Mapping during AF1 in four patients showed that the crista terminalis was a site of functional block. After ablation, evaluation of Halo catheter recordings in three patients showed apparent unidirectional counterclockwise block, whereas analysis of basket catheter recordings demonstrated complete bidirectional block. The apparent conduction over the isthmus during pacing from proximal CS was due to conduction along the posterior part of the IVC orifice, which activated the LLRA despite complete isthmus block. CONCLUSION: Our results demonstrate that limited endocardial mapping may yield a pattern compatible with unidirectional block in the IVC-TA isthmus, although bidirectional block is present at this anatomic level.

Atrial Flutter↗

PubMed2000

Electrophysiology of atrial fibrillation: evolving insights.

In the last few years many studies have been performed to better understand the pathophysiological nature of atrial fibrillation (AF). These recent observations provide new insights into the initiation and perpetuation of AF, underlying the importance of the pulmonary veins as major sources of atrial triggers and introducing new concepts such as atrial electrical remodeling and spatial heterogeneity of the electrophysiologic characteristics of this arrhythmia. The purpose of this review was to provide current knowledge about AF electrophysiology in an effort to unite old models and new concepts.

Animals↗

PubMed1999

Living anatomy of the atrioventricular junctions. A guide to electrophysiologic mapping. A Consensus Statement from the Cardiac Nomenclature Study Group, Working Group of Arrhythmias, European Society of Cardiology, and the Task Force on Cardiac Nomenclature from NASPE.

Current nomenclature for the atrioventricular (AV) junctions derives from a surgically distorted view, placing the valvar rings and the triangle of Koch in a single plane with antero-posterior and right-left lateral coordinates. Within this convention, the aorta is considered to occupy an anterior position, although the mouth of the coronary sinus is shown as being posterior. Although this nomenclature has served its purpose for the description and treatment of arrhythmias dependent on accessory pathways and atrioventricular nodal reentry, it is less than satisfactory for the description of atrial and ventricular mapping. To correct these deficiencies, a consensus document has been prepared by experts from the Working Group of Arrhythmias of the European Society of Cardiology and the North American Society of Pacing and Electrophysiology. It proposes a new anatomically sound nomenclature that will be applicable to all chambers of the heart. In this report, we discuss its value for description of the AV junctions, establishing the principles of this new nomenclature.

Atrioventricular Node↗

PubMed1999

Which strategy is "best" after myocardial infarction? The Beta-blocker Strategy plus Implantable Cardioverter Defibrillator Trial: rationale and study design.

The Beta-blocker Strategy plus Implantable Cardioverter Defibrillator (BEST-ICD) Trial is a multicenter prospective randomized trial that started in June 1998, in 95 centers in Italy and Germany. The trial will test the hypothesis whether, in high-risk post myocardial infarction (MI) patients already treated with beta blockers, electrophysiologic study (EPS)-guided therapy (including the prophylactic implantation of implantable cardioverter defibrillator [ICD] in inducible patients) will improve survival compared with conventional therapy. Patients eligible for the study are survivors of recent MI (> or = 5 and < or = 21 days), aged < or = 80 years, with left ventricular ejection fraction < or = 35% and > or = 1 of the following additional risk factors: (1) ventricular premature beats > or = 10/hour; (2) decreased heart rate variability (standard deviation of unusual RR intervals < 70 msec); and (3) presence of ventricular late potentials. Furthermore, all enrolled patients must be able to tolerate at least 25 mg of metoprolol per day. These patients constitute about 9% of all patients with recent MI and are expected to have a 2-year all-cause mortality > 25% of which 50% is anticipated to be from sudden death. The main criteria of exclusion from the study are (1) a history of sustained ventricular arrhythmia; (2) documentation of nonsustained ventricular tachycardia during the screening phase; and (3) the need for myocardial revascularization and contraindications or intolerance to beta-blocker therapy. Eligible patients will be randomized to 2 different therapeutic strategies: conventional strategy or EPS/ICD strategy. Patients allocated to the EPS/ICD strategy will undergo further risk stratification, and electrophysiologically inducible patients (approximately 35%) will receive prophylactic ICDs, in addition to the conventional therapy, whereas noninducible patients will be only conventionally treated. The primary endpoint of the study will be death from all causes. By hypothesizing a 30% reduction in the 2-year mortality (from 20% to 14%) in the EPS/ICD group compared with conventionally treated patients, 1,200 patients will have to be included. A triangular, 2-sided sequential design with preset boundaries, for a 5% significance level and 90% power to detect a reduction in 2-year mortality from 20% to 14%, will be used to permit early termination of the trial if the strategy is found to be efficacious, no difference, or inefficacious.

Adrenergic beta-Antagonists↗

PubMed1999

Interruption of the inferior extension of the compact atrioventricular node underlies successful radio frequency ablation of atrioventricular nodal reentrant tachycardia.

A recent anatomic study has revived interest in the inferior extensions of the compact atrioventricular node in humans. The rightward extension is on the right atrial aspect, close to the septal attachment of the tricuspid valve leaflet and, hence, closely related to the anticipated slow pathway considered to play a role in atrioventricular nodal reentrant tachycardia (AVNRT). This report documents a patient, 65 years of age, with dilated cardiomyopathy and AVNRT. The tachycardia was successfully terminated using selective radiofrequency (RF) ablation, delivered at a site where a slow potential was recorded and validated by atrial pacing, located between the tricuspid valve and the os of the coronary sinus (CS), close to its superior rim. In subsequent years the patient developed progressive heart failure and eventually died. Histopathologic examination revealed extensive scar tissue at the site of the burn, extending onto the crest of the underlying ventricular septum. Serial sections revealed the compact AV node superiorly and an inferior extension surfacing from the scar which could be traced inferiorly beyond the os of the CS. This is the first documentation of RF ablation interrupting an inferior extension of the compact AV node in a patient successfully ablated for AVNRT. The observation suggests that the slow pathway in this patient found its anatomic substrate in the inferior extension of the compact AV node.

Aged↗

PubMed1999

Living anatomy of the atrioventricular junctions. A guide to electrophysiological mapping. A Consensus Statement from the Cardiac Nomenclature Study Group, Working Group of Arrythmias, European Society of Cardiology, and the Task Force on Cardiac Nomenclature from NASPE. North American Society of Pacing and Electrophysiology.

Current nomenclature for atrioventricular junctions derives from a surgically distorted view, placing the valvar rings and the triangle of Koch in a single plane with antero-posterior and right-left lateral coordinates. Within this convention, the aorta is considered to occupy an anterior position, while the mouth of the coronary sinus is shown as being posterior. While this nomenclature has served its purpose for the description and treatment of arrhythmias dependent on accessory pathways and atrioventricular nodal re-entry, it is less than satisfactory for the description of atrial and ventricular mapping. To correct these deficiencies, a consensus document has been prepared by experts from the Working Group of Arrhythmias of the European Society of Cardiology, and the North American Society of Pacing and Electrophysiology. It proposes a new, anatomically sound, nomenclature that will be applicable to all chambers of the heart. In this report, we discuss its value as regards the description of the atrioventricular junctions, establishing the principles of this new nomenclature.

Atrioventricular Node↗

PubMed1999

Catheter ablation in a patient with a congenital giant right atrial diverticulum presented as Wolff-Parkinson-White syndrome.

A young woman symptomatic for tachycardia showed right ventricular preexcitation on the surface ECG with a pattern during induced atrial fibrillation suggestive of multiple APs. Noninvasive imaging techniques performed prior to catheter ablation demonstrated the presence of a giant right atrial diverticulum confirmed by hemodynamic procedure. This structure functioned as an enormous accessory AP. We performed catheter ablation of this pathway using a special 4-mm multipolar catheter inside the diverticulum. This is the first case of such as anomaly being successfully treated with catheter ablation.

Adult↗

PubMed1999

ESCWGA/NASPE/P experts consensus statement: living anatomy of the atrioventricular junctions. A guide to electrophysiologic mapping. Working Group of Arrhythmias of the European Society of Cardiology. North American Society of Pacing and Electrophysiology.

Current nomenclature for the AV junctions derives from a surgically distorted view, placing the valvar rings and the triangle of Koch in a single plane with anteroposterior and right-left lateral coordinates. Within this convention, the aorta is considered to occupy an anterior position, whereas the mouth of the coronary sinus is shown as being posterior. Although this nomenclature has served its purpose for the description and treatment of arrhythmias dependent on accessory pathways and AV nodal reentry, it is less than satisfactory for the description of atrial and ventricular mapping. To correct these deficiencies, a consensus document has been prepared by experts from the Working Group of Arrhythmias of the European Society of Cardiology and from the North American Society of Pacing and Electrophysiology. It proposes a new, anatomically sound, nomenclature that will be applicable to all chambers of the heart. In this report, we discuss its value for description of the AV junctions and establish the principles of this new nomenclature.

Atrioventricular Node↗