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Biomedical subjects

G Tomassoni

Publications and source records attributed to G Tomassoni.

At least 19 recordsLinked to original sources
PubMed2001

Ventricular tachycardias arising from the aortic sinus of valsalva: an under-recognized variant of left outflow tract ventricular tachycardia.

OBJECTIVES: To describe a normal heart left bundle branch block, inferior axis ventricular tachycardia (VT), that could not be ablated from the right or left ventricular outflow tracts. BACKGROUND: Whether these VTs are epicardial and can be identified by a specific electrocardiographic pattern is unclear. METHODS: Twelve patients with normal heart left bundle branch block, inferior axis VT and previously failed ablation were included in this study. Together with mapping in the right and left ventricular outflow tracts, we obtained percutaneous epicardial mapping in the first five patients and performed aortic sinus of Valsalva mapping in all patients. RESULTS: No adequate pace mapping was observed in the right and left ventricular outflow tracts. Earliest ventricular activation was noted in the epicardium and the aortic cusps. All patients were successfully ablated from the aortic sinuses of Valsalva (95% CI 0% to 18%). The electrocardiographic pattern associated with this VT was left bundle branch block, inferior axis and early precordial transition with Rs or R in V2 or V3. Ventricular tachycardia from the left sinus had rS pattern in lead I, and VT from the noncoronary sinus had a notched R wave in lead I. None of the patients had complications and all remained arrhythmia-free at a mean follow-up of 8 +/- 2.6 months. CONCLUSIONS: Normal heart VT with left bundle branch block, inferior axis and early precordial transition can be ablated in the majority of patients from either the left or the noncoronary aortic sinus of Valsalva.

Adolescent↗
PubMed2001

A simple method of mapping atrial premature depolarizations triggering atrial fibrillation.

Atrial premature depolarizations (APDs) originating from focal sites, particularly the pulmonary veins (PV), may become triggers of atrial fibrillation (AF). Accurate mapping of APDs with conventional methods may be time consuming and expose the patient to unnecessary instrumentation of the left atrium. We hypothesized that the atrial activation sequence recorded using a simple system that includes an esophageal catheter and a custom-made 16-electrode catheter with two sets of floating electrodes eight in the coronary sinus and eight in the high right atrium) could be sufficient to localize the APDs. The study included 29 patients with frequent APDs and AF refractory to antiarrhythmic medications. The APD site of origin was confirmed with single-point sequential mapping techniques using the CARTO system ten patients) or by placement of multielectrode catheters in the right and left PV (19 patients). Of the 29 patients, 20 patients had a single APD focus; 8 patients had two different APD morphologies; and 1 patient had three APD foci. Mapping for ablation of the APD foci showed earliest activation in the left superior PV in 12 patients, right superior PV in 15 patients, right middle PV in 4 patients, right inferior PV in 1 patient, the lingular branch of the left superior PV in 2 patients, left inferior PV in 2 patients, and right atrium along the crista terminalis in 3 patients. The activation sequence and relative timing of the recordings obtained with our catheter configuration was highly predictive of right and left atrial origin and, more importantly, of right and left PV foci.

Atrial Fibrillation↗
PubMed2001

Ablation of incisional atrial tachycardias using a three-dimensional nonfluoroscopic mapping system.

Incisional atrial reentrant tachycardias are macroreentrant arrhythmias in which surgical scars or prosthetic material constitute one of the constraining barriers of the circuit. Accurate reconstruction based on fluoroscopy-guided endocardial mapping of the reentrant circuit is often incomplete and time consuming explaining, at least in part, the modest long-term results of this technique. Mapping and ablation of these arrhythmias using a three-dimensional nonfluoroscopic mapping system that allows electroanatomic reconstruction of the reentrant circuit could help in identifying the ablation targets and improve long-term outcome. The study included 20 patients (12 men, mean age 45+/-18 years) with corrected congenital heart disease (4 patients), coronary artery bypass surgery (7 patients), mitral or aortic valve replacement or reconstruction (6 patients), valve replacement and coronary revascularization (2 patients), and mitral valve replacement with maze procedure for atrial fibrillation (1 patient). Endocardial mapping with this novel system was complemented by standard electrophysiological techniques used to identify a critical isthmus of conduction. Two or more nonconductive areas of atrial tissue or surgical prosthetic material delimiting a critical isthmus of conduction were identified in every patient. Radiofrequency linear applications spanning two to more boundaries successfully eliminated the tachycardia in every patient. At a follow-up of 11.5+/-5.1 months (range 17-5 months), two (10%) patients developed a new clinical arrhythmia. The remaining 18 had no recurrences off medical therapy. Mean fluoroscopy time was 45.7+/-15.2 minutes for patients with a single scar and 89+/-41.2 minutes in patients with two or more scars. In conclusions, this new nonfluoroscopic mapping system offers the opportunity to achieve a high rate of cure of complex macroreentrant atrial tachycardias by facilitating reconstruction of the macroreentrant circuit and its boundaries.

Adult↗
PubMed2001

Empirical pulmonary vein isolation in patients with chronic atrial fibrillation using a three-dimensional nonfluoroscopic mapping system: long-term follow-up.

The purpose of this study was to assess the feasibility and long-term results of empirical isolation of both superior pulmonary veins in patients with chronic AF. Although localizing and ablating the focal triggers of AF has been proven an effective approach, this strategy is time consuming, often requires multiple procedures, and carries the risk of pulmonary vein stenosis. Whether ostial electrical isolation of the superior pulmonary veins, without initial detailed mapping, is a more efficient approach is not known. The study included 71 consecutive patients who had chronic AF. Using a nonfluoroscopic electroanatomic mapping system, the left and right superior pulmonary veins were ablated circumferentially at the venoatrial junction, with the aim of achieving electrical isolation of the veins. Following ablation, if frequent atrial ectopies were present, mapping and ablation were considered. The patients were periodically followed with 48-hour Holter and loop recorder monitoring. After the ablation of the right and left superior pulmonary veins 59 (83%) of 71 patients maintained sinus rhythm without premature atrial beats. The remaining 12 patients underwent further mapping and ablation including 5 patients who required isolation of the left inferior pulmonary veins. True electrical isolation could be achieved only in 45 (31%) of the 147 targeted veins. At the latest follow-up (mean 29 +/- 8 months), 80% of the patients with upper vein isolation remained in sinus rhythm off medications, 62% of the patients maintained sinus rhythm on previously ineffective medications, and 17% continued to be in AF. Fourteen (20%) patients developed intermittent episodes of left atrial flutter, and mapping in these patients revealed large electrically silent areas in the left atrium. Empirical isolation of pulmonary veins appeared to be an effective approach to help maintain sinus rhythm in patients with chronic AF. True electrical isolation of the pulmonary veins was associated with a higher likelihood of long-term success. Left atrial flutter was seen in a significant number of patients at long-term follow-up.

Atrial Fibrillation↗
PubMed2000

Prospective randomized comparison of antiarrhythmic therapy versus first-line radiofrequency ablation in patients with atrial flutter.

BACKGROUND: Despite the high success rate of radiofrequency (RF) ablation, pharmacologic therapy is still considered the standard initial therapeutic approach for atrial flutter. OBJECTIVE: We prospectively compared the outcome at follow-up of patients with atrial flutter randomly assigned to drug therapy or RF ablation. METHODS: Patients with at least two episodes of symptomatic atrial flutter in the last four months were randomized to regimens of either antiarrhythmic drug therapy or first-line RF ablation. After institution of therapy, end points included recurrence of atrial flutter, rehospitalization and quality of life. RESULTS: A total of 61 patients entered the study, 30 of whom were randomized to drug therapy and 31 to RF ablation. After a mean follow-up of 21 +/- 11 months, 11 of 30 (36%) patients receiving drugs were in sinus rhythm, versus 25 of 31 (80%) patients who underwent RF ablation (p < 0.01). Of the patients receiving drugs, 63% required one or more rehospitalizations, whereas post-RF ablation, only 22% of patients were rehospitalized (p < 0.01). Following RF ablation, 29% of patients developed atrial fibrillation which was seen in 53% of patients receiving medications (p < 0.05). Sense of well being (pre-RF 2.0 +/- 0.3 vs. post-RF 3.8 +/- 0.5, p < 0.01) and function in daily life (pre-RF 2.3 +/- 0.4 vs. post-RF 3.6 +/- 0.6, p < 0.01) improved after ablation, but did not change significantly in patients treated with drugs. CONCLUSION: In a selected group of patients with atrial flutter, RF ablation could be considered a first-line therapy due to the better success rate and impact on quality of life, the lower occurrence of atrial fibrillation and the lower need for rehospitalization at follow-up.

Aged↗
PubMed2000

Catheter ablation approach on the right side only for paroxysmal atrial fibrillation therapy: long-term results.

We report the long-term follow-up of a right side only catheter ablation approach for paroxysmal AF. Eighteen patients with AF refractory to drugs entered the study. Ablation was attempted in the right atrium only by creating linear lesions based on a specific design including from two to four linear lesions. Induction of AF was attempted before ablation and after placement of the lesions. A septal lesion was performed in nine patients. In ten patients atrial defibrillation thresholds (ADFTs) before ablation and following creation of the linear lesions were compared. After a mean follow-up of 22 +/- 11 months, seven patients had recurrence of AF, and another nine patients experienced atrial flutter or atrial tachycardia. Five patients remained in sinus rhythm without medications and four required the use of drugs. Three patients had sporadic AF and six were in chronic AF. The recurrence rate was similar in patients with and without the septal lesion. However, a cure with right side ablation appeared to be predicted by the presence of disorganized and earlier activity in the high right atrium and crista terminalis. Linear lesions in the right atrium were associated with a lower ADFT (pre 2.6 +/- 04 J vs post 1.7 +/- 0.6 J). In conclusion, in a small number of patients, control of AF can be obtained with a right side only approach. Certain activation patterns may identify patients suitable to this approach. No specific lesion pattern appeared more effective. Right atrial linear lesions resulted in lower ADFT.

Atrial Fibrillation↗
PubMed1999

Effect of increased parasympathetic and sympathetic tone on internal atrial defibrillation thresholds in humans.

UNLABELLED: Although changes in autonomic tone affect ventricular defibrillation, little is known about the effect of increased parasympathetic or sympathetic tone on the atrial defbrillation threshold. METHODS: To evaluate the effect of reflexly increased parasympathetic and increase alpha- and beta-adrenergic tone on the atrial defibrillation threshold (ADFT), atrial fibrillation was induced in 14 patients. ADFTs, right atrial refractory period (RARP), and monophasic action potential duration (MAPD) were determined before and after autonomic intervention. ADFTs were determined with a step-up protocol using 3/3-ms biphasic shocks delivered through decapolar catheters in the right atrial appendage and coronary sinus. Two groups were studied. Group I (N = 8) had ADFTs determined at baseline, after receiving phenylephrine (PE), and with PE plus atropine (A). Group 2 (N = 6) had ADFTs determined at baseline and after receiving isoproterenol (ISO). RESULTS: Group I: PE significantly increased sinus cycle length (SR-CL) compared to baseline (742 +/- 123 to 922 +/- 233 ms) without significantly changing RARP, MAPD, or ADFT (2.3 +/- 1.3 J vs 2.3 +/- 0.8 J). With PE + A, SR-CL significantly decreased (529 +/- 100 ms vs 742 +/- 123 ms) and MAPD shortened (231 +/- 41 ms vs 279 +/- 49 ms) without altering RARP or ADFT (1.94 +/- 0.9 J vs 2.25 +/- 1.25 J). Group 2: ISO decreased SR-CL (486 +/- 77 ms vs 755 +/- 184 ms) and MAPD (169 +/- 37 ms vs 226 + 58 ms) but not RARP or ADFT (2.25 +/- 1.21 J vs 2.33 +/- 1.75 J). CONCLUSIONS: Increasing parasympathetic, alpha-, or beta-adrenergic tone does not affect the ADFT despite causing significant electrophysiological changes in the atria.

Adolescent↗
PubMed1999

AV node ablation and pacemaker implantation after withdrawal of effective rate-control medications for chronic atrial fibrillation: effect on quality of life and exercise performance.

We assess whether AV node ablation and pacemaker implantation after discontinuation of effective rate-control medical therapy for chronic atrial fibrillation had a positive impact on quality of life and exercise performance. To assess the possibility of a placebo effect following pacemaker implantation, the study included three groups of patients. Group 1 underwent an echocardiogram, treadmill exercise, and quality of life measurement 1 month prior to and 6 months following AV node ablation and pacemaker implantation associated with discontinuation of rate-control medications. Group 2 underwent AV node ablation and pacemaker implantation without discontinuation of antiarrhythmic rate-control drugs. Group 3 underwent pacemaker implantation without performing AV node ablation and continuing rate-control medical therapy. At the 1- and 6-month evaluation, the patients in group 1 showed a significant improvement of left ventricular ejection fraction, quality of life, and activity scores. The exercise duration and the maximal VO2 consumption, however, did not change significantly. A slight improvement of the quality of life and physical activity scores was observed in the group undergoing AV node ablation without withdrawal of medications. However, no significant changes were observed in the group receiving only the pacemaker without modification of medical therapy and with intact AV node conduction. In conclusion, in patients with chronic atrial fibrillation, discontinuation of effective rate-control medical therapy followed by AV node ablation and permanent pacing appeared to improve quality of life and activity scores despite no change in exercise duration. The improvement observed does not seem to reflect a placebo effect.

Aged↗
PubMed1999

Epicardial mapping and radiofrequency catheter ablation of ischemic ventricular tachycardia using a three-dimensional nonfluoroscopic mapping system.

Endocardial radiofrequency catheter ablation of ischemic left ventricular tachycardia has been of variable success due to multiple factors. Two such factors include the location of the reentrant circuit in the deep myocardium or on the epicardial surface and the inherent limitations of fluoroscopy as a guide for target localization. We report a patient in whom successful epicardial mapping and radiofrequency catheter ablation of an ischemic left ventricular tachycardia was performed using pericardial access and the CARTO electroanatomic mapping system.

Aged↗
PubMed1998

Use of sublingual nitroglycerin during head-up tilt-table testing in patients >60 years of age.

Previous work had demonstrated a reduced specificity associated with head-up tilt protocols using high-dose isoproterenol in patients between 20 and 50 years of age. We evaluated the specificity of head-up tilt testing using different isoproterenol infusion doses and administration of nitroglycerin in patients aged >60 years. In addition, whether the same protocols have impact on the sensitivity of the test was also assessed. One hundred sixty subjects were included in this study. Seventy-six were volunteers randomized to either head-up tilt test with low-dose, 3- and 5-microg/min of isoproterenol (group I) or to a protocol including 0.4 mg of sublingual nitroglycerin (group II). In addition, after an upright tilt drug-free state, 58 patients with a history of syncope underwent repeat head-up tilt with increasing doses of isoproterenol infusion, followed by sublingual nitroglycerin if the test result remained negative. The remaining 33 patients were subjected to the nitroglycerin protocol after the drug-free state phase. In the control groups, the incidence of false-positive responses was 88% and 95%, respectively. In patients with syncope after a negative test result during 5 microg of isoproterenol infusion, nitroglycerin administration increased the number of positive responses from 45% to 79%. The percentage of positive tilt in patients undergoing nitroglycerin administration after the drug-free state part of the protocol was 78%. Administration of nitroglycerin was the most significant predictor of a positive upright tilt in patients with syncope. In subjects aged >60 years, head-up tilt protocols with high-dose isoproterenol infusion and nitroglycerin maintained an adequate specificity. In this subset of patients, nitroglycerin seemed to provide a better sensitivity than isoproterenol.

Administration, Sublingual↗
PubMed1998

QT prolongation and dispersion in myocardial ischemia and infarction.

The ability of QT interval dispersion to predict the occurrence of ventricular fibrillation (VF) after acute myocardial infarction treated with thrombolytic therapy is controversial. Continuous 12-lead electrocardiographic (ECG) monitoring for 48 hours or longer provides an opportunity to detect transient changes of QT dispersion and correlate such changes with the clinical outcome. In 543 consecutive patients enrolled in the TAMI-9 and GUSTO I studies, serial changes of the QT dispersion were analyzed in an attempt to predict the occurrence of VF with a system that monitored continuously the 12-lead ECG and stored it at least every 20 minutes. Measurements of QT dispersion were made at a median time of 2.37 hours after the onset of chest pain and at 24- and 48-hour intervals. A total of 43 patients experienced VF during the acute phase of myocardial infarction; of these patients, 33 (77%) had anterior infarcts. However, despite the higher preponderance of anterior myocardial infarcts in the VF group, patients with anterior infarcts did not have longer QT dispersion than those with other infarct locations. Similarly, no significant differences in the QT dispersion were observed at any time between the group with VF and that without. Women had increased QT dispersion in the initial and 24-hour ECG as compared with men (P = .005). However, this normalized at the 48-hour measurements. Despite this difference, there was no higher incidence of VF in female patients. In conclusion, the data suggest that QT dispersion alone is not sufficient to explain the occurrence of VF in the acute phase of myocardial infarction after thrombolytic therapy.

Electrocardiography↗
PubMed1998

Prospective evaluation of new and old criteria to discriminate between supraventricular and ventricular tachycardia in implantable defibrillators.

This study was designed to evaluate the ability to distinguish between supraventricular tachycardias (SVTs) and ventricular tachycardias (VTs) based on onset, stability, and width criteria in an implantable defibrillator. Inappropriate detection of atrial fibrillation and sinus tachycardia is a common problem in patients with implantable defibrillators. The onset, stability, and width criteria were studied in 17 patients who underwent implantation of a Medtronic 7218C implantable defibrillator by inducing sinus tachycardia and atrial fibrillation. Additional data on the width criteria was obtained by pacing at separate sites in both the left and right ventricle. Patients were studied at different times for up to 6 months to determine any changes in the criteria. The onset and stability criteria caused inappropriate detections in 36% and 12% of the episodes, respectively. The addition of the width criteria decreased the inappropriate detection using the onset and stability criteria to 5% and 2%, respectively. Pacing from the RV apex, RV outflow tract, and LV apex was appropriately detected as wide in 76%, 41%, and 94%, respectively. The width criteria changed over time in individual patients, but was stable by 6 months in all but one patient. No single criterion is satisfactory for distinguishing between SVT and VT in this patient population, but the combination of criteria seems to provide better discrimination. The width criteria can change dramatically over time and needs to be monitored carefully. Newer algorithms will need to be developed to allow better detection of supraventricular tachycardias.

Aged↗
PubMed1998

Effect of the superior vena cava electrode surface area on defibrillation threshold in different lead systems.

Little data is available comparing the efficacy of the Transvene, Endotak C 70 series, and the active CAN configuration on defibrillation success. In addition, the impact of the superior vena cava (SVC) electrode surface area and length on the active CAN system is unknown. Therefore, we compared the defibrillation efficacy of the Transvene and Endotak C 70 series lead systems with and without the active CAN in dogs. Defibrillation threshold (DFT) testing was randomly performed in 20 dogs. In protocol I (10 dogs), DFT energy was compared in three RV/SVC lead systems with an SVC electrode defibrillating surface area of 90 mm2 (Transvene-90), 160 mm2 (Transvene-160), 617 mm2 (Endotak), and an RV/CAN configuration. In protocol II (10 dogs), DFT comparison was performed in the Transvene-90/CAN, Transvene-160/CAN, Endotak/CAN, and RV/CAN configurations. In protocol I, increasing the SVC surface area from 90 to 160 mm2 and from 160 to 617 mm2 significantly lowered DFT energy. The Endotak and the RV/CAN systems provided the lowest DFT energy requirements. In protocol II, the Endotak/CAN system significantly lowered DFT energy compared to the other three lead configurations. In both protocols, the impedance decreased as the SVC surface area increased from 90 to 160 mm2. However, no significant reduction in DFT impedance occurred as the SVC surface area increased from the Transvene-160 to the Endotak lead. Increasing the SVC surface area from 90 to 617 mm2 in a two coil lead system lowered DFT energy to similar levels provided by the RV/CAN configuration. The addition of an SVC electrode with a surface area of 90 or 160 mm2 did not reduce DFT energy compared to the RV/CAN configuration. The Endotak/CAN system, however, provided the lowest DFT requirements.

Animals↗
PubMed1998

Effect of skin electrode location on radiofrequency ablation lesions: an in vivo and a three-dimensional finite element study.

INTRODUCTION OBJECTIVES: To assess the effect of skin electrode location on radiofrequency (RF) ablation lesion dimensions and energy requirements. BACKGROUND: Little is known about the effects of skin electrode location on RF ablation lesion dimensions and efficiency. METHODS AND RESULTS: Temperature-controlled ablation at 60 degrees C for 60 seconds was performed in six sheep. Paired lesions were created in the lateral, anterior, posterior, and septal walls of both the ventricles. For group 1 lesions, the skin electrode was positioned directly opposite the catheter tip (optimal). For group 2 lesions, we used either the standard posterior location or an anterior location if the posterior skin electrode location was used for group 1. Group 1 lesions were 5.8+/-0.8 mm deep and 9.3+/-1.9 mm wide, compared with 4.6+/-1.0 mm deep and 7.7+/-1.9 mm wide group 2 lesions (P < or = 0.001). Group 1 lesion dimensions also had less variability. A finite element model was used to simulate temperature-controlled ablation and to study the effect of skin electrode locations on lesion dimensions, ablation efficiency, and blood heating. The optimal location was 1.6 times more efficient, and the volume of blood heated to > or = 90 degrees C was 0.005 mm3 for optimal versus 2.2 mm3 for the nonoptimal location. CONCLUSION: Optimal skin electrode placement: (1) creates deeper and larger lesions; (2) reduces lesion size variability; and (3) decreases blood heating.

Animals↗