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Fiorenzo Gaita

Publications and source records attributed to Fiorenzo Gaita.

13 recordsLinked to original sources
PubMed2003

Short QT Syndrome: a familial cause of sudden death.

BACKGROUND: A prolonged QT interval is associated with a risk for life-threatening events. However, little is known about prognostic implications of the reverse-a short QT interval. Several members of 2 different families were referred for syncope, palpitations, and resuscitated cardiac arrest in the presence of a positive family history for sudden cardiac death. Autopsy did not reveal any structural heart disease. All patients had a constantly and uniformly short QT interval at ECG. METHODS AND RESULTS: Six patients from both families were submitted to extensive noninvasive and invasive work-up, including serial resting ECGs, echocardiogram, cardiac MRI, exercise testing, Holter ECG, and signal-averaged ECG. Four of 6 patients underwent electrophysiological evaluation including programmed ventricular stimulation. In all subjects, a structural heart disease was excluded. At baseline ECG, all patients exhibited a QT interval <or=280 ms (QTc <or=300 ms). During electrophysiological study, short atrial and ventricular refractory periods were documented in all and increased ventricular vulnerability to fibrillation in 3 of 4 patients. CONCLUSIONS: The short QT syndrome is characterized by familial sudden death, short refractory periods, and inducible ventricular fibrillation. It is important to recognize this ECG pattern because it is related to a high risk of sudden death in young, otherwise healthy subjects.

Adolescent↗
PubMed2003

Functional and echocardiographic improvement following multisite biventricular pacing for congestive heart failure.

BACKGROUND: Heart failure remains a major cause of morbidity and mortality despite advances in pharmacological treatment. Recently, multisite biventricular pacing has been used in the treatment of patients with heart failure. OBJECTIVES AND METHODS: The short and medium term effects of this treatment modality were assessed, and the association between baseline clinical characteristics and the positive response to treatment was investigated. Consecutive patients who received this treatment modality were included. They underwent comprehensive clinical and echocardiographic assessment including a 6 min walk at baseline, one month and three months. RESULTS: Between January 1998 and June 1999, 95 patients received multisite biventricular pacing therapy in the three participating hospitals. In 63 patients with complete three-month follow-ups, there were improvements from baseline to three-month follow-up in New York Heart Association heart failure (3.3 +/- 0.5 to 2.2 +/- 0.6, P<0.001) and 6 min walk (305 +/- 120 to 403 +/- 113 m, P<0.001). Significant salutary changes in echocardiographic measurements were also observed in left ventricular (LV) diastolic dimension, ejection fractions (EFs), interventricular contraction delay and severity of mitral regurgitation (MR). The 63 patients were categorized into responders (n=42) and nonresponders (n=21) based on the clinical response. Clinical characteristics were similar between the two groups. The responders had a more pronounced decrease in QRS width. An increase in LVEF and a reduction in LV diastolic dimension, interventricular mechanical delay and severity of MR were observed in the responders but not in the nonresponders. Furthermore, there was a positive association between the reduction in QRS width and the increase in LVEF. CONCLUSIONS: Cardiac resynchronization by means of multisite pacing appears to be a promising therapy in the treatment of heart failure. The salutary clinical response is associated with echocardiographic improvement.

Aged↗
PubMed2003

Safety and efficacy of cryoablation of accessory pathways adjacent to the normal conduction system.

UNLABELLED: Cryoablation of Septal Accessory Pathways. INTRODUCTION: Catheter ablation has become a routine treatment for patients with Wolff-Parkinson-White syndrome because of its low risk and high efficacy; however, radiofrequency ablation in the septum close to the AV node or His bundle still carries a definite risk for AV block. Cryoenergy catheter ablation has recently become available. This technique has specific features, such as the ability to create reversible loss of function to predict the effects of ablation (ice mapping) and the adherence of the catheter tip to the endocardium with freezing, which avoids the risk for dislodgment. Both of these characteristics may minimize the risk of complications. The aim of this study was to analyze the effectiveness and safety of catheter cryoablation in 20 patients with para-Hisian or midseptal accessory pathways (AP). METHODS AND RESULTS: Eleven patients with para-Hisian and 9 patients with midseptal AP underwent catheter cryoablation. Ice mapping at -30 degrees C was performed to ascertain the disappearance of AP conduction and the absence of impairment of AV nodal conduction. If the expected result was obtained, cryoablation was performed by lowering the temperature to -75 degrees C for 4 minutes in order to create a permanent lesion. Cryoablation was successful in all patients using a mean of 1.2 +/- 0.4 applications. Recurrences occurred in 4 patients (20%) who underwent a second successful cryoablation session. No complications were observed. CONCLUSION: Cryoablation appears to be a safe and effective technique for ablation of APs close to the AV node or His bundle because of the ability to predict the acute effects of ablation with ice mapping before creation of an irreversible lesion.

Arrhythmias, Cardiac↗
PubMed2003

Percutaneous catheter cryothermal ablation of atrioventricular nodal reentrant tachycardia: efficacy and safety of a new ablation technique.

BACKGROUND: Radiofrequency catheter ablation is nowadays a widely used technique for the treatment of arrhythmias; however, due to the possible complications such as atrioventricular block when radiofrequency is delivered in the septal area, this type of energy is not optimal. In contrast, cryoenergy has several positive features; first of all, it allows for the creation of reversible lesions and hence to test the effects of the ablation while the lesion is still forming thus reducing the number of ineffective and useless lesions. In addition, it also allows for the evaluation of the acute effects on the structures adjacent to the ablation site. The aim of the present study was to analyze the effectiveness and safety of catheter cryoablation in the treatment of atrioventricular nodal reentrant tachycardia (AVNRT). METHODS: Thirty-two patients presenting with AVNRT underwent catheter cryoablation using a 7F catheter. When the optimal parameters were recorded, "ice mapping" at -30 degrees C was performed for 80 s to validate the ablation site by means of a reversible lesion. If the expected result was achieved, the cryoablation was carried out lowering the temperature to -75 degrees C for 4 min thus creating a permanent lesion. RESULTS: Slow pathway ablation guided by a slow pathway potential was successfully performed in 31 out of the 32 patients with a mean of 2.6 +/- 1.0 cryoapplications. No complications occurred in any patients. Transient AH prolongation was observed in 2 patients in a midseptal site during the ice mapping phase of AVNRT ablation. CONCLUSIONS: Cryoablation is a safe and effective technique for AVNRT ablation. It may be useful particularly when the ablation must be performed close to the atrioventricular node or His bundle, due to the possibility of validating the site of ablation by means of ice mapping that creates only a reversible lesion.

Adolescent↗
PubMed2003

Electropharmacological effects of antiarrhythmic drugs on atrial fibrillation termination. Part I: Molecular and ionic fundamentals of antiarrhythmic drug actions.

In the last few years many studies have been performed with the aim of gaining a better understanding of the pathophysiological nature of atrial fibrillation. These recent observations provide new insights into the initiation and perpetuation of atrial fibrillation, underlying the importance of the pulmonary veins as major sources of atrial triggers and introducing new concepts such as the atrial electrical remodeling and the spatial heterogeneity of the electrophysiological characteristics of this arrhythmia. The increasing knowledge about the cardiac ion channel structure and function and about the electrophysiological actions of the antiarrhythmic drugs may contribute to a better comprehension of the mechanisms of the pharmacological termination of the arrhythmia. In part I of the review we try to give a unified vision of the old models and new concepts about the molecular and ionic fundamentals of antiarrhythmic drug actions.

Anti-Arrhythmia Agents↗
PubMed2003

Electropharmacological effects of antiarrhythmic drugs on atrial fibrillation termination. Part II: New insights into the electrophysiological mechanisms of atrial fibrillation termination.

Antiarrhythmic drugs have been largely used to convert atrial fibrillation to sinus rhythm. Classes Ia, Ic and III antiarrhythmic agents are all known to be effective. Nevertheless, the electrophysiological properties of such agents even of the same class are very different. The mechanisms of the pharmacological termination of atrial fibrillation is an interesting issue that has not been so extensively studied yet. In this review we try to summarize the principal concepts about the electrophysiological substrate of atrial fibrillation and to give a unified and modern overview of the issue of the mechanisms of the pharmacological termination of the arrhythmia.

Anti-Arrhythmia Agents↗
PubMed2002

Surgical approaches to atrial fibrillation.

Atrial fibrillation (AF) remains an unsurmounted hurdle toward the cure of supraventricular arrhythmias. Despite its high prevalence, a definitive treatment approach has not been established. AF is triggered in most cases by early premature atrial beats and is maintained by anomalies of the substrate. Elimination or modification of either one or both may be effective in the cure of AF. Surgical ablation, which originated with the favorable results of the Maze procedure developed by Cox, has an important role in the cure of AF associated with heart diseases that require cardiac surgery. This is due to the high success rate and to the simplification of the procedure now used which has resulted in reduction of the procedural time and complications. Various techniques have been proposed, however, it is noteworthy that the posterior part of the left atrium and the ostia of pulmonary veins are involved in all approaches despite the different energy sources used (radiofrequency or cryo energy) and the different design of the intended lesion. These results imply that the posterior part of the left atrium is crucial in the genesis and maintenance of atrial fibrillation. On the other hand, it is not clear if the results of the ablation are due to the linear lesions that modify the substrate or to the electrical isolation that eliminate the triggers. A thorough electrophysiological evaluation post ablation has been performed only in few cases. Greater understanding of the mechanism of success of surgical ablation may advance the development and success of other approaches. Considering that surgical ablation is usually performed in patients with permanent AF, linear lesions modifying the substrate together with pulmonary vein isolation have shown better results than the elimination of the triggers with a pure electrical isolation of the pulmonary veins. Prevention of AF recurrences has been relatively good, however some severe complications (atrioesophagus fistula, coronary artery damage, etc.) have been reported. Considering the relatively benignity of AF in absence of associated cardiopathy, the risk of complications should discourage widespread application of surgical ablation in patients with lone AF. On the contrary it should be routinely proposed in most patients with permanent or paroxysmal AF undergoing cardiac surgery.

Atrial Fibrillation↗
PubMed2002

Cryothermic ablation within the coronary sinus of an epicardial posterolateral pathway.

Radiofrequency ablation inside the coronary sinus (CS) is associated with the risk of vein stenosis, or perforation or damage to the circumflex artery. Cryothermic ablation has proved less harmful, but there are no data on its use within a venous structure. A patient with a posterolateral accessory pathway underwent several unsuccessful attempts at endocardial ablation. Ablation then was performed with cool energy within the CS, where the shortest VA interval and a possible Kent potential were recorded. Selective left coronary angiography showed a normal circumflex artery and the absence of lesions of the CS. Six months later, the patient was asymptomatic without taking antiarrhythmic drugs. We conclude that cryoablation within the CS may be effective and safe.

Adult↗
PubMed2002

A method for quantifying atrial fibrillation organization based on wave-morphology similarity.

A new method for quantifying the organization of single bipolar electrograms recorded in the human atria during atrial fibrillation (AF) is presented. The algorithm relies on the comparison between pairs of local activation waves (LAWs) to estimate their morphological similarity, and returns a regularity index (rho) which measures the extent of repetitiveness over time of the detected activations. The database consisted of endocardial data from a multipolar basket catheter during AF and intraatrial recordings during atrial flutter. The index showed maximum regularity (rho = 1) for all atrial flutter episodes and decreased significantly when increasing AF complexity as defined by Wells (type I: rho = 0.75 +/- 0.23; type II: rho = 0.35 +/- 0.11; type III: rho = 0.15 +/- 0.08; P < 0.01). The ability to distinguish different AF episodes was assessed by designing a classification scheme based on a minimum distance analysis, obtaining an accuracy of 85.5%. The algorithm was able to discriminate among AF types even in presence of few depolarizations as no significant rho changes were observed by reducing the signal length down to include five LAWs. Finally, the capability to detect transient instances of AF complexity and to map the local regularity over the atrial surface was addressed by the dynamic and multisite evaluation of rho, suggesting that our algorithm could improve the understanding of AF mechanisms and become useful for its clinical treatment.

Algorithms↗
PubMed2002

Local electrogram assessment of unidirectional isthmus block is sufficient to predict the acute and long-term success of cavo-tricuspid isthmus ablation.

BACKGROUND: This study investigated whether a minimal approach to typical atrial flutter ablation using an 8 mm tip catheter with a 150 W generator with only the documentation of clockwise block by means of local criteria predicts a good long-term outcome. METHODS: Seventy patients underwent typical atrial flutter ablation. A multipolar catheter was inserted into the coronary sinus (CS) and an 8 mm tip ablation catheter was used to ablate and map the isthmus. The ablation line was performed in the posteroseptal region. The clockwise block was confirmed by recording a corridor of double potentials along the line and by counterclockwise activation of the portion of the isthmus just beyond the lesion line as demonstrated by measuring the conduction times during CS pacing. RESULTS: In case of block, the mean distance between the two split atrial electrograms was 129 +/- 31 ms. Acute isthmus block was achieved in all 70 patients. The median of the radiofrequency pulses was 10 (range 1-36). No immediate or late complications were noted. The long-term follow-up (19.5 +/- 4 months) revealed recurrence of typical atrial flutter in 2 cases (2.8%). CONCLUSIONS: Our results demonstrate that the acute success rate following typical atrial flutter isthmus ablation using an 8 mm tip catheter with a 150 W generator is high. No complications occurred. Moreover, the documentation of just the clockwise isthmus block using a minimal approach according to local electrogram criteria is a good predictor of the long-term success.

Atrial Flutter↗
PubMed2002

[Refractory heart failure. Multisite stimulation].

The pathophysiological background of cardiac resynchronization therapy is represented by the intraventricular conduction delay such as left bundle branch block, present in about one third of patients with dilated cardiomyopathy. Intraventricular conduction block, with or without atrioventricular delay, adversely influences ventricular function due to unsynchronized contraction and is associated with a poor prognosis. Contractile dyssynchrony and abnormal atrioventricular delay can be corrected by non-conventional stimulation modalities such as left ventricular pacing or biventricular pacing associated with preexcitation to restore the physiological atrioventricular timing. Over the last decade several studies have reported the short- or long-term favorable effects of resynchronization therapy on the left ventricular function and remodeling, the quality of life, the functional capacity, the adrenergic activity, and the reduced rehospitalization rate. The most significant results have been reported in patients with a QRS duration > or = 150 ms, while the InSync Italian Registry has shown improvement even in patients with a QRS duration < 150 ms as well as in patients with atrial fibrillation. On the basis of such data it may be argued that the activation sequence of the different walls of the left ventricle is likely more important than the QRS duration. Inclusion criteria commonly used in the published or ongoing trials are: moderate to severe congestive heart failure (NYHA functional class III-IV) on optimized pharmacological treatment; left ventricular ejection fraction < or = 35%; left ventricular diastolic diameter > 60 mm; end-diastolic mitral regurgitation; no need of conventional pacing. While with regard to the surrogate endpoints the results of published trials are very encouraging, we do not yet know whether resynchronization therapy prolongs the life expectancy of patients with heart failure. Studies able to provide important answers to these problems are near completion. In the meanwhile, in agreement with the guidelines of the European Society of Cardiology, it seems prudent to employ such a therapy only in case of patients satisfying the above-mentioned criteria.

Heart Failure↗