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Tamas Szili-Torok

Publications and source records attributed to Tamas Szili-Torok.

18 recordsLinked to original sources
PubMed2006

Right diaphragmatic paralysis following endocardial cryothermal ablation of inappropriate sinus tachycardia.

Inappropriate sinus tachycardia (IST) is a rare disorder amenable to catheter ablation when refractory to medical therapy. Radiofrequency (RF) catheter modification/ablation of the sinus node (SN) is the usual approach, although it can be complicated by right phrenic nerve paralysis. We describe a patient with IST, who had symptomatic recurrences despite previous acutely successful RF SN modifications, including the use of electroanatomical mapping/navigation system. We decided to try transvenous cryothermal modification of the SN. We used 2 min applications at -85 degrees C at sites of the earliest atrial activation guided by activation mapping during isoprenaline infusion. Every application was preceded by high output stimulation to reveal phrenic nerve proximity. During the last application, heart rate slowly and persistently fell below 85 bpm despite isoprenaline infusion, but right diaphragmatic paralysis developed. At 6 months follow-up, the patient was asymptomatic and the diaphragmatic paralysis had partially resolved. This is the first report, we believe, of successful SN modification for IST by endocardial cryoablation, although this case also demonstrates the considerable risk of right phrenic nerve paralysis even with this ablation energy.

Catheter Ablation↗
PubMed2006

One-year follow-up in a prospective, randomized study comparing radiofrequency and cryoablation of arrhythmias in Koch's triangle: clinical symptoms and event recording.

AIMS: To rely solely on clinical symptoms of recurrent palpitations to evaluate the success of interventional procedures can be misleading. This study was designed to assess the efficacy of event recording in evaluating long-term success in patients treated for atrioventricular nodal reentrant tachycardia (AVNRT) or right posteroseptally located accessory pathways (RPS) either by radiofrequency (RF) or by cryoablation (CA). METHODS AND RESULTS: Sixty-three patients with AVNRT and eight with RPS were randomized. Patients were encouraged to activate an event recorder in the case of recurrent palpitations for the first 3 months. One year after the procedure, patients were asked specific arrhythmia related questions. Thirty-six patients underwent RF and 35 CA. Acute success was finally achieved in 34 (94%) patients in the RF and 33 (94%) in the CA groups. Assessment of long-term success demonstrated a similar proportion of palpitations in the RF and CA groups: 11 (31%) vs. 17 (49%). Only 12 patients activated the event recorder, four patients in RF, including one patient with chest pain, and eight in the CA group. Analysis of recordings revealed recurrent AVNRT or circus movement tachycardia in four patients (one RF and three CA), atrial fibrillation in one RF patient, and sinus tachycardia in six (one RF and five with CA). In addition, a complete 12 lead ECG of a recurrent arrhythmia was made in three RF and two CA patients (in-hospital or after the event recording). A total of seven patients underwent a second procedure (four RF and three CA). Without the event recorder, seven patients would have been misclassified as having recurrent arrhythmia. CONCLUSION: Event recording enhances the sensitivity of detecting arrhythmia recurrences in evaluating therapy efficacy and should be considered in every interventional follow-up study. Analysis of recordings showed that CA is as effective as RF in the treatment of AVNRT and RPS at long-term follow-up.

Arrhythmias, Cardiac↗
PubMed2006

A simple algorithm for defining the mechanism and the chamber of origin in atrial tachycardias.

INTRODUCTION: Although macroreentrant atrial tachycardia (MRAT) and focal atrial tachycardia (FAT) can be successfully cured by catheter ablation, the proper diagnosis and treatment of these arrhythmias can still be challenging. AIM: The objective of this study is to develop an algorithm allowing rapid diagnosis of the mechanism and the chamber of origin of atrial tachycardia based on intracardiac catheter recordings from the right atrium and the coronary sinus (CS). METHODS: A 2-stepped algorithm was designed: (1) The time of biatrial activation expressed as a percentage of the tachycardia cycle length served to discriminate FAT from MRAT. (2) In FAT, the direction of activation of the CS catheter and the earliest atrial activation were used to define the chamber of origin. In MRAT, the time of right atrium activation was determined or entrainment was used at different sites. Thirty-two intracardiac recordings were reviewed off-line after the algorithm by 4 electrophysiologists blinded to the mechanism and the chamber of origin. The results of their analysis were compared with the intraoperative diagnosis. RESULTS: The algorithm correctly identified 11 (100%) of 11 FATs and 19 (90.4%) of 21 MRATs. The site of origin was correctly identified in 8 (72.7%) of 11 FATs and in 20 of 21 (95.2%) MRATs. The site of origin was misidentified in 3 FATs, all arising from the CS ostium. CONCLUSIONS: This algorithm allows rapid discrimination between FAT and MRAT. The chamber of origin is detected with a high accuracy in MRAT. However, the earliest atrial activation taken as an isolated event is not a good predictor for the chamber of origin in FAT arising from the ostium of the CS.

Algorithms↗
PubMed2005

Defibrillation efficacy testing: long-term follow-up and mortality.

AIMS: Extensive defibrillation threshold testing is no longer necessary to perform as devices have become more effective. We assessed the lowest effective defibrillation (LED) level at implantation and before hospital discharge and related this to outcome. METHODS AND RESULTS: One hundred and twenty-seven consecutive patients with biphasic shock and active can devices were studied at intraoperative and predischarge testing. A subgroup of 67 patients had > or = 3 VF inductions at implant. Improvement was defined when LED decreased by > or = 3 J. The LED was significantly higher at implantation compared with predischarge (P < 0.001). Improvement was seen in 73/127 patients (58%). In the group with > or = 3 VF inductions, an implantation LED > 9 J was related to a lower LVEF (P < 0.01); 34/67 patients (51%) had improvement in LED. During follow-up, 18/127 patients died, four received heart transplantation. No different outcome was observed in patients with and without improvement. However, for those with > or = 3 VF inductions, an independent predictor of mortality was implantation LED > 9 J without improvement on the second test. Safety margin < 10 J was not related to mortality. CONCLUSION: Repeated defibrillation efficacy testing before hospital discharge may confirm that a relatively high defibrillation energy is required. This is related to a higher mortality in long-term follow-up.

Adult↗
PubMed2005

The presence of contractile reserve has no predictive value for the evolution of left ventricular function following atrio-ventricular node ablation in patients with permanent atrial fibrillation.

AIMS: Transcatheter ablation of the atrio-ventricular (AV) node followed by ventricular pacing has been shown to improve symptoms and quality of life (QOL) of patients with permanent atrial fibrillation (AF). In a considerable number of patients, cardiac function deteriorates after AV node ablation. We aimed to determine whether the absence of contractile reserve assessed by low dose dobutamine stress echocardiography (LDDSE) could identify those patients whose left ventricular (LV) function deteriorates after AV node ablation. METHODS: All 25 patients studied had permanent AF for at least 12 months. LVEF was determined 6 days and 3 months after AV node ablation by radionuclide ventriculography (RNV), at a paced rate of 80 beats/min. Deterioration in cardiac function was defined as a decrease in LVEF>5%. LDSE was performed in all patients before and after ablation. The presence of contractile reserve was defined as an improvement in regional function of >or=1 grade at low dose dobutamine in at least 4 segments. QOL measurements were taken using Minnesota, NHBP and MPWB questionnaires. RESULTS: LVEF showed no improvement in the overall group (52.8+/-11.1% vs. 51.8+/-9.8%, p=NS). QOL showed significant improvement in all questionnaires (Minnesota: 4.1+/-2.1 vs. 2.5+/-2, p=0.001; NHBP: 54.8+/-43.3 vs. 34.2+/-34.3, p=0.002; MPWB: 22.2+/-4.6 vs. 19.4+/-6.2, p=0.03). There was no significant difference in change of LVEF between patients with and without contractile reserve (-0.4+/-8.7 vs. 1.6+/-11.3, p=NS). However, patients with a preserved LVEF at baseline showed more frequently a reduced LVEF after AV node ablation (62.2+/-10.4% vs. 47.5+/-7.6%, p=0.001). CONCLUSIONS: (1) The absence of contractile reserve does not predict deterioration of cardiac function after AV node ablation. (2) AV node ablation results in a significant improvement in QOL, which is not necessarily associated with improvement of LVEF. (3) Higher baseline LVEF predicts deterioration of cardiac function. These data suggest that although AV node ablation is an excellent way of controlling symptoms, it should be avoided in patients with normal LV function.

Adult↗
PubMed2005

Slow and wide QRS complex tachycardia as a unique complication following radiofrequency catheter ablation of a left-sided accessory pathway in a child.

Radiofrequency lesions can, theoretically, be the substrate for new persistent arrhythmias. As far as we know, this has never previously been encountered after transcatheter ablation of accessory pathways. A child with Wolff-Parkinson-White syndrome was referred for radiofrequency catheter ablation of a left-sided accessory pathway. After successful ablation of the accessory pathway using a retrograde transaortic approach, the child developed an incessant wide QRS complex tachycardia at slow rate that was resistant to pharmacologic interventions. The focus of the tachycardia was identical to the ventricular site of insertion of the eliminated accessory pathway.

Catheter Ablation↗
PubMed2004

Ablation lesions in Koch's triangle assessed by three-dimensional myocardial contrast echocardiography.

BACKGROUND: Myocardial contrast echocardiography (MCE) allows visualization of radiofrequency (RF) ablation lesions in the left ventricle in an animal model. AIM: To test whether MCE allows visualization of RF and cryo ablation lesions in the human right atrium using three-dimensional echocardiography. METHODS: 18 patients underwent catheter ablation of a supraventricular tachycardia and were included in this prospective single-blind study. Twelve patients were ablated inside Koch's triangle and 6, who served as controls, outside this area. Three-dimensional echocardiography of Koch's triangle was performed before and after the ablation procedure in all patients, using respiration and ECG gated pullback of a 9 MHz ICE transducer, with and without continuous intravenous echocontrast infusion (SonoVue, Bracco). Two independent observers analyzed the data off-line. RESULTS: MCE identified ablation lesions as a low contrast area within the normal atrial myocardial tissue. Craters on the endocardial surface were seen in 10 (83%) patients after ablation. Lesions were identified in 11 out of 12 patients (92%). None of the control patients were recognized as having been ablated. The confidence score of the independent echo reviewer tended to be higher when the number of applications increased. CONCLUSIONS: 1. MCE allows direct visualization of ablation lesions in the human atrial myocardium. 2. Both RF and cryo energy lesions can be identified using MCE.

Catheter Ablation↗
PubMed2004

Guiding and optimization of resynchronization therapy with dynamic three-dimensional echocardiography and segmental volume--time curves: a feasibility study.

OBJECTIVE: To assess a new approach for guiding and hemodynamic optimization of resynchronization therapy, using three-dimensional (3D) transthoracic echocardiography. BACKGROUND: Resynchronization therapy for heart failure provides the greatest hemodynamic benefit when applied to the most delayed left ventricular (LV) site. Currently, the ideal LV pacing site is selected according to acute invasive hemodynamic assessment and/or tissue Doppler imaging. METHODS: A total of 16 patients with advanced heart failure and an implanted biventricular pacemaker were included in this study. Transthoracic apical LV images at equidistant intervals were obtained using a prototype, fast-rotating second harmonic transducer to reconstruct 3D LV datasets during sinus rhythm (SR), right ventricular (RV) apical and biventricular pacing mode. A semi-automated contour analysis system (4D LV analysis, TomTec, Germany) was used for segmental wall motion analysis and identification of the most delayed contracting segment and calculation of global LV function. RESULTS: Data acquisition duration was 10 s and analyzable 3D images were obtained in 12 patients. Of these patients, data during SR were available in 9 and during biventricular pacing in 11. The greatest contraction delay during SR was found in the anterior and antero-septal segments in five of nine patients. Biventricular pacing resulted in reduction of the contraction delay in seven of eight patients. The global LV function did not change significantly. CONCLUSION: 3D echocardiography with appropriate analytic software allows detection of the most delayed LV contracting segment and can be used to select the optimal pacing site during resynchronization therapy.

Aged↗
PubMed2004

Ice mapping during cryothermal ablation of accessory pathways in WPW: the role of the temperature time constant.

AIM: Cryothermal energy has the ability reversibly to demonstrate loss of function with cooling, ice mapping, at less deep temperatures. The purpose of this study was to investigate the time course of the temperature during ice mapping of accessory pathways. METHODS AND RESULTS: Thirteen patients with the Wolff-Parkinson-White (WPW) syndrome underwent cryoablation. After identification of a prospective ablation site, ice mapping was performed by cooling the tip to a minimum of -30 degrees C. Successful ice mapping was defined by loss of accessory pathway (AP) conduction. A total of 104 ice maps were analyzed. Successful ice mapping was demonstrated in 17 attempts. There was no significant difference in mapping temperature between successful and unsuccessful ice mapping (-29.4+/-3.2 degrees Celsius vs -30.4+/-1.7 degrees Celsius). The temperature time constant tau during successful ice mapping was significantly shorter compared with unsuccessful ice mapping (7.0+/-1.1 s vs 10.1+/-1.3 s; P<0.0001). The response time (RT) to mapping temperature of -30 degrees C was significantly prolonged in unsuccessful ice mapping attempts (35.8+/-4.5 s vs 53.5+/-11.0 s; P<0.0001). Significant correlations were found between successful ice mapping and the temperature time constant, and between RT and the temperature time constant (P<0.001). CONCLUSION: The ability to identify prospective ablation sites by ice mapping was demonstrated. Successful ice mapping attempts were characterized by a short temperature time constant and a short response time to mapping temperature with a sudden disappearance of pathway conduction.

Adult↗
PubMed2003

Dynamic three-dimensional echocardiography combined with semi-automated border detection offers advantages for assessment of resynchronization therapy.

Simultaneous electrical stimulation of both ventricles in patients with interventricular conduction disturbance and advanced heart failure improves hemodynamics and results in increased exercise tolerance, quality of life. We have developed a novel technique for the assessment and optimization of resynchronization therapy. Our approach is based on transthoracic dynamic three-dimensional (3D) echocardiography and allows determination of the most delayed contraction site of the left ventricle (LV) together with global LV function data. Our initial results suggest that fast reconstruction of the LV is feasible for the selection of the optimal pacing site and allows identifying LV segments with dyssynchrony.

Arrhythmias, Cardiac↗
PubMed2003

The Australian Intervention Randomized Control of Rate in Atrial Fibrillation Trial (AIRCRAFT).

OBJECTIVES: The Australian Intervention Randomized Control of Rate in Atrial Fibrillation Trial was a multicenter trial of atrioventricular junction ablation and pacing (AVJAP) compared with pharmacologic ventricular rate control (medication [MED]) in patients with mild to moderately symptomatic permanent atrial fibrillation (AF). BACKGROUND: There have been very few prospective randomized trials, undertaken in highly symptomatic patients, comparing AVJAP with pharmacologic methods of ventricular rate control for patients with permanent AF. METHODS: There were 99 patients (70 men, mean age 68 +/- 8.6 years) at five centers. Forty-nine patients were randomized to AVJAP while 50 patients were randomized to pharmacologic control. The primary end point was cardiac function measured by echocardiography and exercise tolerance. The secondary end points were ventricular rate control, evaluated by 24-h ambulatory electrocardiographic monitoring, and quality of life. Data were collected at randomization and then at one month, six months, and 12 months post-randomization. RESULTS: At 12 months follow-up there was no significant difference in left ventricular ejection fraction (AVJAP: 54 +/- 17%; MED: 61 +/- 13% [p = ns]) or exercise duration on treadmill testing (AVJAP: 4.1 +/- 2 min; MED: 4.6 +/- 2 min [p = ns]); however, the peak ventricular rate was lower in the AVJAP group during exercise (112 +/- 17 beats/min vs. 153 +/- 36 beats/min, p < 0.05) and activities of daily life (117 +/- 16 beats/min vs. 152 +/- 37 beats/min, p < 0.05). The CAST quality-of-life questionnaire revealed that patients in the AVJAP group had fewer symptoms at six months (p = 0.003) and at 12 months (p = 0.004). The observed relative risk reduction in symptoms at 12 months was 18%. Global subjective semiquantitative measurement of quality of life using the "ladder of life" revealed that the AVJAP group reported a 6% better quality of life at six months (p = 0.011). CONCLUSIONS: In this trial, AVJAP for patients with mild to moderately symptomatic permanent AF did not worsen cardiac function during long-term follow-up, and quality of life was improved.

Activities of Daily Living↗
PubMed2003

Effects of septal pacing on P wave characteristics: the value of three-dimensional echocardiography.

Interatrial septum (IAS) pacing has been proposed for the prevention of paroxysmal atrial fibrillation. IAS pacing is usually guided by fluoroscopy and P wave analysis. The authors have developed a new approach for IAS pacing using intracardiac echocardiography (ICE), and examined its effects on P wave characteristics. Cross-sectional images are acquired during pullback of the ICE transducer from the superior vena cava into the inferior vena cava by an electrocardiogram- and respiration-gated technique. The right atrium and IAS are then three-dimensionally reconstructed, and the desired pacing site is selected. After lead placement and electrical testing, another three-dimensional reconstruction is performed to verify the final lead position. The study included 14 patients. IAS pacing was achieved at seven suprafossal (SF) and seven infrafossal (IF) lead locations, all confirmed by three-dimensional imaging. IAS pacing resulted in a significant reduction of P wave duration as compared to sinus rhythm (99.7 +/- 18.7 vs 140.4 +/- 8.8 ms; P < 0.01). SF pacing was associated with a greater reduction of P wave duration than IF pacing (56.1 +/- 9.9 vs 30.2 +/- 13.6 ms; P < 0.01). P wave dispersion remained unchanged during septal pacing as compared to sinus rhythm (21.4 +/- 16.1 vs 13.5 +/- 13.9 ms; NS). Three-dimensional intracardiac echocardiography can be used to guide IAS pacing. SF pacing was associated with a greater decrease in P wave duration, suggesting that it is a preferable location to decrease interatrial conduction delay.

Adult↗
PubMed2002

Interatrial septum pacing guided by three-dimensional intracardiac echocardiography.

OBJECTIVES: Currently, the interatrial septum (IAS) pacing site is indirectly selected by fluoroscopy and P-wave analysis. The aim of the present study was to develop a novel approach for IAS pacing using intracardiac echocardiography (ICE). BACKGROUND: Interatrial septum pacing may be beneficial for the prevention of paroxysmal atrial fibrillation. METHODS: Cross-sectional images are acquired during a pull-back of the ICE transducer from the superior vena cava into the inferior vena cava by an electrocardiogram- and respiration-gated technique. Both atria are then reconstructed using three-dimensional (3D) imaging. Using an "en face" view of the IAS, the desired pacing site is selected. Following lead placement and electrical testing, another 3D reconstruction is performed to verify the final lead position. RESULTS: Twelve patients were included in this study. The IAS pacing was achieved in all patients including six suprafossal (SF) and six infrafossal (IF) lead locations all confirmed by 3D imaging. The mean duration times of atrial lead implantation and fluoroscopy were 70 +/- 48.9 min and 23.7 +/- 20.6 min, respectively. The IAS pacing resulted in a significant reduction of the P-wave duration as compared to sinus rhythm (98.9 +/- 19.3 ms vs. 141.3 +/- 8.6 ms; p < 0.002). The SF pacing showed a greater reduction of the P-wave duration than IF pacing (59.4 +/- 6.6 ms vs. 30.2 +/- 13.6 ms; p < 0.004). CONCLUSIONS: Three-dimensional ICE is a feasible tool for guiding IAS pacing.

Adult↗
PubMed2002

A cool ablation.

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Atrioventricular Node↗
PubMed2002

Transthoracic defibrillation of short-lasting ventricular fibrillation: a randomised trial for comparison of the efficacy of low-energy biphasic rectilinear and monophasic damped sine shocks.

BACKGROUND: Biphasic rectilinear shocks are more effective than monophasic shocks for transthoracic atrial defibrillation and for ventricular arrhythmias during electrophysiological testing. We undertook the present study to compare the efficacy of 100 J rectilinear biphasic waveform shocks with 150 J monophasic damped sine waveform shocks for transthoracic defibrillation of true ventricular fibrillation during defibrillation threshold testing (DFT). The second aim of the study was to analyse the influence of patch positions on the efficacy of defibrillation. METHODS: 50 episodes of 14 patients (age ranging from 37 to 82 years) who underwent DFT testing were randomised for back-up shocks with either a sequence of 100 and 200 J biphasic waveform, or a sequence of 150 and 360 J conventional monophasic shocks. A binary search protocol was used at implantation and before hospital discharge. Patients were also randomised to an anteroposterior position versus a right-anterior-apical position. A crossover was performed between implantation and pre-hospital discharge for biphasic versus monophasic sequence as well as for the 2 different positions. RESULTS: After failed internal shocks, 27 episodes were treated with biphasic, and 23 with monophasic shocks. The first attempt by the external device did not terminate II episodes (2 biphasic, 9 monophasic). The first shock efficacy was significantly greater with biphasic than with monophasic shocks (p < 0.02). The overall success rate was 93% with biphasic shocks and 64% with monophasic shocks. In multivariate regression analysis including patch position, arrhythmia duration, type of waveform, testing order and session, only waveform was associated with successful defibrillation (p < 0.02). CONCLUSION: For transthoracic defibrillation of ventricular fibrillation, low-energy rectilinear biphasic shocks are more effective than monophasic shocks. The position of the defibrillation shock pads has no influence on the biphasic shock efficacy, but anteroposterior pad position is more effective using monophasic shocks.

Adult↗