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Biomedical subjects

Bernhard Zrenner

Publications and source records attributed to Bernhard Zrenner.

At least 37 records · Page 2Linked to original sources
PubMed2005

Paradoxical atrial undersensing due to inappropriate atrial noise reversion of atrial fibrillation in dual-chamber pacemakers.

UNLABELLED: Paradoxical atrial undersensing. BACKGROUND: Paradoxical atrial undersensing at high atrial sensing levels was described as false atrial noise reversion of dual-chamber pacemakers during atrial fibrillation in a sheep model. It is unknown whether this phenomenon occurs in humans. METHODS: In total, 71 patients with implanted dual-chamber pacemakers and atrial fibrillation were tested for the occurrence of paradoxical atrial undersensing. After determination of the sensing threshold of atrial fibrillation (30 seconds of continuous mode switch), the atrial sensing level was stepwise increased. If, after correct mode switch behavior at insensitive levels, loss of mode switch occurred at higher sensing levels and if the pacing mode was consistent with atrial noise reversion, paradoxical atrial undersensing was assumed. RESULTS: Paradoxical atrial undersensing could be provoked in 9 of 71 (13%) patients at a median sensing level of 0.4 (range 0.15-2.0) mV. Six different pacemaker models of five different manufacturers were affected. The occurrence of paradoxical atrial undersensing was significantly associated with the sensing threshold of atrial fibrillation (2.7+/-1.5 mV for patients with paradoxical undersensing compared to 1.6+/-1.3 mV for those without, P=0.02). Decreasing the atrial sensing level avoided paradoxical undersensing in 8 of 9 patients while maintaining an adequate safety margin for the detection of atrial fibrillation. CONCLUSION: Paradoxical atrial undersensing is inherent to all current dual-chamber pacemakers. The incidence is about 13% when using very high atrial sensing levels. Inappropriate atrial noise reversion can be resolved in most of the cases by decreasing atrial sensing levels and knowledge of this phenomenon is important to avoid unwarranted atrial lead revisions.

Aged↗
PubMed2004

Transvenous cryoablation versus radiofrequency ablation of the slow pathway for the treatment of atrioventricular nodal re-entrant tachycardia: a prospective randomized pilot study.

AIMS: This is a prospective, randomized study comparing transvenous cryoablation with radiofrequency (RF) ablation of atrioventricular nodal re-entrant tachycardia (AVNRT). METHODS AND RESULTS: In this pilot trial, 200 patients with AVNRT were randomized to undergo cryoablation or RF ablation of the slow pathway. A 7 Fr 4-mm-tip cryocatheter (Cryocath) was used for cryomapping and cryoablation. Cryomapping was performed at the temperature of -30 degrees C to test the effect on the candidate ablation site. Following successful cryomapping, cryoablation was performed to produce an irreversible lesion by freezing to -75 degrees C. Procedural success, defined as elimination of the slow pathway or noninducibility of AVNRT, was achieved in 97/100 (97%) patients in the Cryo group vs. 98/100 (98%) patients in the RF group. No permanent complete AV-block occurred in either group. During a median of 246 days of follow-up, 8 patients in the Cryo group and 1 in the RF group had AVNRT recurrence. The cumulative incidence of primary endpoint (a combination of procedural failure, permanent complete AV-block and AVNRT recurrence) was significantly higher in the Cryo group than in the RF group (P=0.03, Log-rank test). CONCLUSIONS: The results of this pilot study indicate that transvenous cryoablation using a 4-mm-tip cryocatheter is associated with a comparable acute success rate but a higher recurrence rate as compared with RF ablation in patients with AVNRT. Potential benefits of cryoablation for ablation of AVNRT need to be determined in a larger multi-centre trial.

Adult↗
PubMed2004

Occurrence and management of atrial arrhythmia after long-term Fontan circulation.

OBJECTIVES: In patients after the Fontan operation, we determined risk factors for late failure and for intra-atrial re-entrant tachycardia at 15 to 20 years' follow-up. Midterm results after electrophysiologic ablation therapy for these tachycardias were also evaluated. METHODS: Current follow-up was available in 162 patients (2005 patient-years) with a wide range of underlying diagnoses operated on between February 1978 and May 1995. Risk factor analysis included patient-related and procedure-related variables, with late failure and the incidence of re-entrant tachycardia as outcome parameters. RESULTS: Forty late failures were observed (2.0 per 100 patient-years). At 15 years, Kaplan-Meier estimated survival was significantly (P =.007) better for patients with tricuspid atresia (93%) compared with that for patients with complex congenital malformation (71%). The sole multivariable risk factor for Fontan failure was the type of underlying diagnosis. At 20 years' follow-up, overall freedom from tachycardia was estimated to be 46% +/- 12%. Acute success of electrophysiologic ablation was seen in 25 (83%) of 30 patients, and Kaplan-Meier estimated freedom from recurrent tachycardia was 81% +/- 10% at 3 years. Multivariate analysis identified duration of Fontan circulation as the sole risk factor for re-entrant tachycardias. CONCLUSION: After the modified Fontan operation, long-term survival in patients with tricuspid atresia was significantly better compared with that in patients with complex congenital malformations. As first-choice therapy for atrial re-entrant tachycardias, we recommend electrophysiologic ablation therapy.

Adolescent↗
PubMed2004

Preventricular far-field sensing in the atrial channel of dual chamber pacemakers--an occasional cause of inappropriate mode switch.

INTRODUCTION AND AIMS OF THE STUDY: Atrial oversensing may trigger false positive mode switch to an asynchronous mode in dual chamber pacemakers. While myopotential oversensing and far-field R wave sensing within the postventricular atrial refractory period are well characterized, data about oversensing (near-field P wave or far-field R wave) within the atrioventricular delay is limited. Aim of the study was to determine the incidence of preventricular oversensing in the atrial channel of current dual chamber pacemakers. METHODS: Consecutive patients with dual chamber pacemakers who were in sinus rhythm and who showed no myopotential oversensing were included in the study. Atrial sensitivity was programmed to the maximal available value and atrioventricular delay was prolonged when necessary for intrinsic atrioventricular conduction. RESULTS: Ten out of 100 (10%) patients showed oversensing within the atrioventricular delay at highest levels of atrial sensitivity, median sensing threshold for the signals was 0.35 mV, and the median coupling interval between preventricular atrial oversensing and the ventricular sensed event was 20 ms. CONCLUSION: The incidence of inappropriate mode switch caused by atrial preventricular oversensing related to near-field P wave or far-field R wave oversensing in dual chamber pacemakers is up to 10%. Interpretation of pacemaker Holters should consider oversensing within the atrioventricular delay as a differential diagnosis to true episodes of atrial tachyarrhythmias.

Adolescent↗
PubMed2004

Necessity for biatrial ablation to achieve bidirectional cavotricuspid isthmus conduction block in a patient following senning operation.

We report the case of a 28-year-old male patient with a 17-year history of recurrent symptomatic atrial tachyarrhythmia following Senning operation for transposition of the great arteries. Biatrial electroanatomic mapping and entrainment mapping revealed counterclockwise peri-tricuspid annulus reentry in which cavotricuspid isthmus tissue in both systemic and pulmonary venous atria was involved. Linear ablation of the cavotricuspid isthmus in the pulmonary venous atrium terminated the tachycardia but did not block the isthmus conduction, and the tachycardia was reinduced. Bidirectional isthmus conduction block could be achieved only after additional linear ablation targeting the cavotricuspid isthmus tissue in the systemic venous atrium. We conclude that biatrial ablation may be necessary in order to achieve bidirectional isthmus block and prevent tachycardia recurrence in some patients following Senning or Mustard operation.

Adult↗
PubMed2004

Incidence of antitachycardia therapy suspension due to magnet reversion in implantable cardioverter defibrillators.

Electromagnetic interference may result in transient or persistent suspension of antitachycardia therapies in ICDs. The incidence of such events has not been assessed so far. Patient charts were retrospectively analyzed for the occurrence of temporary suspension of antitachycardia therapies as it is stored in the Holter of St. Jude Medical or Ventritex ICDs. Follow-up data of 46 patients and 83.7-patient years were analyzed. Overall, 43 episodes of transient ICD inactivation occurred. Twenty-two of these episodes were related to intentional ICD inactivation in the emergency room or during surgery and 12 episodes were related to ICD follow-up. In nine episodes an environmental source of electromagnetic interference is presumed. None of the interactions resulted in persistent ICD inactivation or reprogramming of the devices. The risk for temporary suspension of ICD therapies unrelated to surgery, intentional magnet application in the emergency room, or routine follow-up is 11% per patient and year. Evaluation of its potential sources and the prevalence of ICD inhibition is warranted.

Adolescent↗
PubMed2003

Do airport metal detectors interfere with implantable pacemakers or cardioverter-defibrillators?

OBJECTIVES: The aim of this study was to determine whether airport metal detector gates (AMDGs) interfere with pacemakers (PMs) or implantable cardioverter-defibrillators (ICDs). BACKGROUND: It is currently unknown whether AMDGs interfere with implanted PMs or ICDs. METHODS: A total of 348 consecutive patients (200 PM and 148 ICD recipients) have been tested for the occurrence of electromagnetic interference (EMI) within the electromagnetic field of a worldwide-used airport metal detector. RESULTS: No interference, such as pacing or sensing abnormalities, was observed in any of the 200 PM and 148 ICD patients; also no reprogramming occurred. CONCLUSIONS: In vivo testing of PM and ICD systems showed no EMI with a standard AMDG. Clinically relevant interactions with implanted PMs or ICDs seem unlikely.

Adolescent↗
PubMed2003

Circumferential mapping and electric isolation of pulmonary veins in patients with atrial fibrillation.

Information about the clinical efficacy and complications of the circumferential mapping and isolation of the pulmonary veins (PVs) in patients with atrial fibrillation (AF) is still limited. The present study included 75 patients (mean age 58 +/- 11 years, 20 women) with paroxysmal (n = 69) or persistent AF (n = 6). Mapping of PVs was performed with a circumferential mapping catheter. After preferential PV-left atrium (LA) electric inputs were defined, radiofrequency ablation was performed until complete isolation of the PVs from the LA was achieved. A total of 226 PVs were mapped; 195 (86%) showed typical PV potentials. Complete isolation of PVs from the LA was achieved in 173 PVs (89%). Detailed follow-up, including 7-day Holter monitoring at 1, 4, 9, and 12 months after intervention was performed. If AF reoccurred, PVs were mapped and reisolated. After a mean follow-up period of 230 +/- 133 days, 38 of 75 patients (51%) were in sinus rhythm. At 1, 4, and 9 months of follow-up, 31 of 65 patients (48%), 36 of 53 patients (68%, p = 0.04 as compared with the first month), and 21 of 28 patients (75%, p = 0.025 as compared with the first month), respectively, were in sinus rhythm. During follow-up, 30 patients (40%) underwent a second ablation procedure due to recurrence. Recurrences were related to resumption of PV muscle-left atrial conduction (27 patients) and/or extra PV foci (12 patients) or nonablated PVs (8 patients). Complications occurred in 17 patients (22%). PV stenosis was detected in 13 patients (25% to 50% in 7 patients and >50% in 6 patients). Pericardial effusion occurred in 4 patients. It was concluded that isolation of the PV from the LA is moderately effective in the prevention of AF recurrence and could be associated with serious acute and long-term complications.

Adult↗
PubMed2003

Emergency hospital admissions and three-year survival of adults with and without cardiovascular surgery for congenital cardiac disease.

OBJECTIVE: This study determined the quantity and nature of emergencies leading to unscheduled hospital admissions of adults with congenital cardiac disease and their mid-term survival. RESULTS: During 1 year, 429 adults with congenital cardiac diseases were admitted 571 times, and 124 admissions (22%) of 95 patients (22%) were emergency admissions. Fifteen of the 95 patients were seen for the first time in 1 of the participating centers. The underlying anomalies were Fallot's tetralogy and pulmonary atresia (n = 26/7), univentricular heart after Fontan procedure (n = 25), atrial septal defect (n = 18), Eisenmenger syndrome (n = 12), complete transposition (n = 11), and others (n = 25). Indications for admission were cardiovascular complications (n = 103; 83%) (arrhythmia, cardiac failure, syncope, pacemaker problems, pericardial tamponade, and sudden death), infections (n = 8, 6%) (endocarditis, pacemaker infection, pneumonia, and cerebral abscess), acute chest pain (n = 7; 6%), and acute abdominal pain (n = 4; 3%). All patients required immediate emergency care, and 16 patients (17%) required urgent cardiovascular or abdominal surgery. Six patients died during the hospital stay. During a follow-up of 2.9 years (SD 0.8), 16 (18%) of the discharged patients died, and 2 additional patients underwent heart or heart-lung transplantation. CONCLUSION: Adults with congenital cardiac disease often experience serious emergency situations with a high in-hospital and mid-term post-hospital mortality. Care given by physicians with special expertise is important in this specific group of patients.

Adolescent↗
PubMed2003

Acute and long-term results of radiofrequency ablation of common atrial flutter and the influence of the right atrial isthmus ablation on the occurrence of atrial fibrillation.

AIMS: The purpose of this study was to evaluate the acute success rate and long-term efficacy of radiofrequency ablation of common type atrial flutter (AFL) by using a standardised anatomical approach in a large series of patients and to assess the influence of right atrial isthmus ablation on the occurrence of atrial fibrillation. There are no large scale prospective or retrospective multicentre studies for radiofrequency ablation of AFL. METHODS AND RESULTS: The study population consisted of 363 consecutive patients with AFL (mean age 58+/-16 years, 265 men) who underwent radiofrequency ablation at the inferior vena cava-tricuspid annulus (IVC-TA) isthmus using a standardised anatomic approach. Bidirectional isthmus block at the IVC-TA was achieved in 328 patients (90%). Following radiofrequency ablation, 343 patients (95%) were followed for a mean of 496+/-335 days. During the follow-up period, 310 patients (90%) remained free of AFL recurrences. Multivariate analysis identified five independent predictors of AFL recurrence: fluoroscopy time (p<0.001), atrial fibrillation after AFL ablation (p=0.01), lack of bidirectional block (p=0.02), reduced left ventricular function (p=0.035) and right atrial dimensions (p=0.046). Atrial fibrillation occurrence was significantly reduced after AFL ablation (112 in 343 patients, 33%) as compared to occurrence of atrial fibrillation before radiofrequency ablation (198 in 363 patients, 55%, p<0.001). CONCLUSIONS: The current anatomical ablation approach for AFL and criteria for evaluation of the IVC-TA isthmus block is associated with an acute success rate of 90% and a long-term recurrence rate of 10%. Radiofrequency ablation of common AFL results in a significant reduction in the occurrence of atrial fibrillation.

Acute Disease↗
PubMed2003

Strategies to avoid inappropriate therapies due to ventricular double detection in biventricular pacing implantable cardioverter/defibrillators.

Implantation of biventricular pacing implantable cardioverter/defibrillators (ICD) is a new therapeutic approach for the treatment of chronic heart failure and the prevention of sudden cardiac death. Due to a common left and right ventricular sensing channel in first generation biventricular pacing ICD, ventricular double sensing and subsequent delivery of inappropriate therapies occurs in some patients. A case of inappropriate anti-tachycardia pacing due to ventricular double detection is described. After programming short postventricular atrial refractory period, abandoning postventricular atrial refractory period extension in case of ventricular premature beats, increased upper rate limits and after careful selection of tachycardia detection criteria and anti-tachycardia programming no further inappropriate therapy occurred.

Aged↗
PubMed2003

Impact of atrial fibrillation on the voltage of bipolar signals acquired from the left and right atria.

A detailed analysis of the impact of atrial fibrillation (AF) on the voltage of the atrial signals acquired from various right and left atrial regions has not been reported. Thirteen patients (mean age 55 +/- 11 years, range 39-67 years, 5 women) with AF were included in this study. Mapping of the left and the right atrium was performed with 64-electrode basket catheters. AF cycle lengths were calculated over 10-second time intervals using a custom-made software. Voltage of the bipolar signals during AF was calculated by measuring the amplitudes of 30 consecutive signals in the left and the right atria. During sinus rhythm voltage differences between the left (3 +/- 2.9 mV) and the right atrium (2.8 +/- 2.4 mV, P = 0.15) were insignificant. During AF, as compared to sinus rhythm, voltages of the bipolar signals were significantly reduced in the left (0.9 +/- 0.6 mV) and the right (1.3 +/- 1.1 mV) atria (P < 0.001 compared with sinus rhythm). In the left atrium, the posterior wall showed the most pronounced voltage reduction (1.1 +/- 0.8 mV vs 5.3 +/- 4.6 mV, P < 0.001). In the right atrium the septal wall showed the greatest reduction in voltage amplitude (0.8 +/- 0.6 mV vs 2.5 +/- 1.5 mV, P < 0.001). There was a close correlation between the voltage values and the AF cycle length. The smallest voltage values and greatest amplitude reductions were observed during faster and more disorganized AF activity. It is concluded that during AF, the voltage of bipolar signals is significantly reduced as compared to sinus rhythm. The reduction in voltage expresses atrial and regional disparity and correlates strongly with local AF cycle lengths and the degree of AF disorganization.

Adult↗
PubMed2003

Characterization of onset mechanism and waveform analysis in patients with atrial fibrillation using a high-resolution noncontact mapping system.

INTRODUCTION: Information on the spatiotemporal organization of atrial activity at the onset of atrial fibrillation (AF) is limited. METHODS AND RESULTS: The study consisted of 26 consecutive patients (22 men and 4 women; mean age 56 +/- 9 years) with AF in whom the left atrium (LA) was mapped using a noncontact mapping system. At the onset of AF, the AF cycle lengths and wavefronts were analyzed at the site of origin of the triggering atrial premature complex (APC) and five predefined sites within the LA (superior, anterior, posterior, lateral, and septal walls). If repetitive activity was observed at the site of origin of APCs, triggered AF episodes were considered as focally driven. APCs that induced AF had shorter coupling intervals than APCs that did not induce AF (300 +/- 41 msec vs 392 +/- 64 msec, P < 0.001). Immediately after AF onset, repetitive firing was crucial for maintenance of arrhythmia in 52 (80%) of 65 AF episodes. In 13 AF onset episodes (20%), AF was maintained by other mechanisms. The number of LA wavefronts after AF onset was lower in focally driven AF episodes compared with episodes in which no focally driven activity was observed (1.9 +/- 0.6 v. 2.3 +/- 2.3 wavefronts, P < 0.05). After the onset of AF, the posterior wall of the LA showed the earliest disorganized activity (after 5.2 +/- 3.1 cycles). CONCLUSION: In the majority of AF episodes (80%), repetitive firing from the triggering foci may play an important role in maintaining AF immediately after arrhythmia onset. In 20% of the episodes, AF at early stages seems to be maintained by other mechanisms. The capability of APCs to induce AF depends on the coupling interval and the focus localization. The posterior wall of the LA shows the earliest disorganization of wavefronts at the onset of AF.

Adult↗
PubMed2003

Delineation of intra-atrial reentrant tachycardia circuits after mustard operation for transposition of the great arteries using biatrial electroanatomic mapping and entrainment mapping.

INTRODUCTION: Intra-atrial reentrant tachycardia (IART) circuits after Mustard operation remain incompletely understood due to the complex atrial anatomy after extensive surgical procedures. The aim of this study was to delineate IART circuits and their relations to the individual anatomic boundaries in Mustard patients. METHODS AND RESULTS: Twelve patients (10 men and 2 women; age 29 +/- 4.6 years) with atrial tachyarrhythmias after Mustard operation were included in this study. During 14 IARTs and 2 focal atrial tachycardias, electroanatomic mapping and entrainment mapping were performed in both the systemic venous atrium and the pulmonary venous atrium. The latter was accessed via a retrograde transaortic approach. Thirteen IARTs used a single-loop reentrant circuit, and 1 IART used a dual-loop reentrant circuit. Ten (77%) of 13 single-loop reentrant circuits used the tricuspid annulus (TA) as their central barrier. The remaining 3 IARTs rotated around the inferior vena cava (IVC) (n = 2) or ostium of the right upper pulmonary vein (n = 1). In 6 (60%) of the 10 peritricuspid IARTs, both pulmonary venous atrium and systemic venous atrium components of the mid-portion of the TA-IVC isthmus were demonstrated to be part of the reentry. Overall, 12 (86%) of 14 IARTs in 10 patients were successfully ablated by bridging two barriers that constrained the reentrant circuit. Eight (80%) of 10 peritricuspid circuits were abolished by linear ablation connecting the TA to the IVC (n = 4), incisional scar (n = 2), patch (n = 1), and atriotomy (n = 1). CONCLUSIONS: In Mustard patients, the TA serves as the most frequent central barrier of IART. Biatrial electroanatomic mapping combined with entrainment mapping facilitates delineation of IART circuits in relation to their anatomic barriers and enables the design of individual ablation strategies to achieve high success.

Adult↗
PubMed2003

Simultaneous multisite endocardial mapping of sustained and non-sustained atrial fibrillation in humans.

The aim of this study was to investigate the differences between sustained and non-sustained forms of human atrial fibrillation (AF) using multielectrode endocardial recordings. Methods. Sixty-four pole basket catheters were deployed in the right atrium (RA) of 3 groups of patients: 1) patients with persistent AF (> 48 hours); 2) induced sustained AF (> 15 minutes); and 3) induced non-sustained AF (< 15 minutes). Beat to beat AF intervals (FF) were evaluated for each bipole. On the basis of signal characteristics and direction of wavefront propagation, the degree of spatial and temporal organization of AF was assessed. Results. Persistent AF showed the shortest FF intervals (161 ms) and lowest overall degree of AF organization, induced non-sustained AF the longest FF intervals (192 ms) and highest degree of organization. FF intervals of induced sustained AF were only slightly longer (169 ms) compared to persistent AF. Within each AF group, the lateral wall showed the highest degree of organization, the septal region the lowest. Conclusion. In humans, FF interval and overall degree of AF organization were found to increase significantly from sustained to non-sustained AF. Persistent and induced sustained AF, however, only slightly differed in these parameters.

Adult↗
PubMed2002

Biatrial multisite mapping of atrial premature complexes triggering onset of atrial fibrillation.

Pulmonary veins are considered to be the most common origin of the focal activity that triggers the onset of atrial fibrillation (AF). However, little is known about the importance of ectopic activity located outside the pulmonary veins. This study included 45 patients (8 women and 37 men, mean age 55 +/- 12 years) with paroxysmal (n = 25) and persistent (n = 20) AF in whom multisite mapping of the right and left atria was performed using a 64-electrode basket catheter (n = 21) or a noncontact mapping system (n = 24). Spontaneous or orciprenaline-induced atrial premature complexes (APCs) were mapped. In all, 94 AF onsets from 38 distinct foci in 30 patients were observed and analyzed. Of these foci, 20 (53%) were located in pulmonary veins and 18 (47%) were located outside the pulmonary veins in other parts of the atria. In 22 patients (73%), AF was reproducibly induced by APCs from a single focus (59 episodes). In 8 patients (27%), AF originated from 2 distinct foci (35 episodes). Additionally, 20 of 30 patients (67%) who developed AF had APCs in different locations not inducing AF. APCs inducing AF had shorter coupling intervals than APCs not inducing AF (307 +/- 54 vs 409 +/- 76 ms, p <0.001). This study showed that 47% of ectopic foci triggering the onset of AF were located outside the pulmonary veins in extravenous parts of the left atrium and the right atrium, and 27% of patients had AF onsets of bifocal origin. These data challenge the current opinion that extrapulmonary foci play a minor role in inducing AF.

Atrial Fibrillation↗
PubMed2002

Application of right atrial contiguous linear lesions: an in vivo efficacy validation of multipolar ablation catheters in an animal model.

Catheter ablation of atrial flutter and catheter Maze procedures require the creation of linear lesions. The efficacy of different multipolar catheters to create linear contiguous transmural lesions was studied in a sheep model. In 19 sheep a multipolar ablation catheter was inserted into the right atrium. In nine sheep a steerable 7 Fr catheter (C1) with six 6-mm electrodes and in five sheep a steerable 7 Fr catheter (C2) with four 5-mm electrodes were placed. In five sheep a 3.7 Fr catheter (C3) with eight electrodes of 6-mm length was deployed (steerable sheath). A total of 72 linear lesions were created and evaluated. Catheter types C1, C2, and C3 produced continuous lesions with at least two adjacent electrodes in 45%, 79%, and 87% of the lesions. The mean lesion length achieved by C3 was longer compared to C1 and C2 (27 +/- 14 vs 10 +/- 5 and 11 +/- 6 mm; P < 0.05). The ability to produce contiguous lesions by all available electrodes was low: C1, 5%; C2, 5%; and C3, 6%. C3 was most effective in exerting transmural lesions (93% vs C1 75% and C2 57%; P < 0.0001). Microscopic endocardial fibrinous adhesions and macroscopic mild electrode carbonizations were caused by all catheter types. In conclusion, (1) all three catheter types do not create contiguous lesions along all electrodes. Gaps of viable tissue remain in most instances; (2) lesion depths and transmurality varies with different catheters; and (3) potentially hazardous thrombotic material was observed during radiofrequency ablation with all three catheters.

Animals↗