Hendrik Lambert | Ghent University (original) (raw)

Papers by Hendrik Lambert

Springer eBooks, 2000

Background-In patients with atrial fibrillation, intracardiac atrial defibrillation causes discom... more Background-In patients with atrial fibrillation, intracardiac atrial defibrillation causes discomfort. An easily applicable, short-acting analgesic and anxiolytic drug would increase acceptability of this new treatment mode. Methods and Results-In a double-blind, placebo-controlled manner, the effect of intranasal butorphanol, an opioid, was evaluated in 47 patients with the use of a step-up internal atrial defibrillation protocol (stage I). On request, additional butorphanol was administered and the step-up protocol continued (stage II). Thereafter, if necessary, patients were intravenously sedated (stage III). After each shock, the McGill Pain Questionnaire was used to obtain a sensory (S), affective (A), evaluative (E), and total (T) pain rating index (PRI) and a visual analogue scale analyzing pain (VAS-P) and fear (VAS-F). For every patient, the slope of each pain or fear parameter against the shock number was calculated and individual slopes were averaged for the placebo and butorphanol group. All patients were cardioverted at a mean threshold of 4.4Ϯ3.3 J. Comparing both patient groups for stage II, the mean slopes for PRI-T (Pϭ0.0099), PRI-S (Pϭ0.019), and PRI-E (Pϭ0.015) became significantly lower in the butorphanol group than in the placebo group. Comparing patients who received the same shock intensity ending stage I and going to stage II, in those patients randomized to placebo the mean VAS-P (Pϭ0.023), PRI-T (Pϭ0.029), PRI-S (Pϭ0.030), and PRI-E (Pϭ0.023) became significantly lower after butorphanol administration. Conclusions-During a step-up internal atrial defibrillation protocol, intranasal butorphanol decreased or stabilized the value of several pain variables and did not affect fear. Of the 3 qualitative components of pain, only the affective component was not influenced by butorphanol. The PRI evaluated pain more accurately than the VAS. (Circulation.

Journal of Cardiovascular Electrophysiology, Jun 1, 1998

Electrode Length for Atrial Deflbrillation. Introduction: Catheter-based electrodes have heen use... more Electrode Length for Atrial Deflbrillation. Introduction: Catheter-based electrodes have heen used previously to terminate episodes of atrial flhrillation in animals and man. Typically, these electrodes span 6 to 7 cm, and lowest energy requirements are achieved when these electrodes are positioned in the distal coronary sinus and in the right atrium. The purpose of this study was to evaluate the use of longer electrode lengths for atrial deflbrillation. Methods and Results: In 15 patients, two decapolar catheters were inserted, one into the distal coronary sinus and one in the right atrium. To provide longer electrodes lengths, a third catheter was inserted and alternated positioned in the right atrium or coronary sinus. A 6-cm electrode span was ohtained by using the distal 8 rings on the coronary sinus catheter or 8 consecutive electrodes on the right atrial catheter and increased from 6 to 11 cm by connecting 5 consecutive, nonoverlapping rings of the third catheter with the 10 rings of the initial right atrial or coronary sinus catheter. Atrial defihrillation thresholds were determined twice, in a randomized order, in each patient for each of the three combinations of electrode lengths. All 15 patients could he successfully converted to sinus rhythm without complications; however, one patient could be converted reproducihiy with only 2 of the 3 electrode combinations. Mean thresholds were 306 ± 102 V, 5.9 ± 4.0 J for the 6 cm/6 cm electrode length comhination with an impedance of 72 ± 18 U. For the electrode combination using the U-cm electrode in the right atrium, the deHhrillation threshold was 296 ± 107 V, 5.8 ± 3.9 J with an impedance of 61 ± 17 SI and was 294 ± 91 V, 5.6 ± 3.6 J with an impedance of 55 ± 11 n for the 11-cm electrode in the coronary sinus. There were no .significant differences in defihrillation voltage or energy (P > 0.05) associated with the longer electrode lengths; however, the longer electrode lengths did significantly lower shock impedance (P < 0.05). Conclusion: The use of longer electrodes, when using the right atrium to coronary sinus shock vector, does not lower the defibrillation requirements for restoration of sinus rhythm.

Heart Rhythm, 2012

OBJECTIVES The aim of this multicenter study was to evaluate the device-and procedure-related saf... more OBJECTIVES The aim of this multicenter study was to evaluate the device-and procedure-related safety of a novel force-sensing radiofrequency (RF) ablation catheter capable of measuring the real-time contact force (CF) and to present CF data and its possible implications on patient safety. BACKGROUND The clinical outcome of RF ablation for the treatment of cardiac arrhythmias may be affected by the CF between the catheter tip and the tissue. Insufficient CF may result in an ineffective lesion, whereas excessive CF may result in complications. METHODS Seventy-seven patients (43 with right-sided supraventricular tachycardia [SVT] and 34 with atrial fibrillation [AF]) received percutaneous ablation with the novel studied catheter. The CF applied and safety events related to the procedure were reported. RESULTS CF values at mapping ranged from 8 Ϯ 8 to 60 Ϯ 35 g and from 12 Ϯ 10 to 39 Ϯ 29 g in the SVT group and the LA group, respectively, showing a significant interinvestigator variability (P Ͻ .0001). High transient CFs (Ͼ100 g) were noted in 27 patients (79%) of the LA group. One device-related complication (tamponade, 3%) occurred in the AF group.

Heart Rhythm, Nov 1, 2012

Journal of Cardiovascular Electrophysiology, 2010

Effect of Ablation Electrode Contact Force. Introduction: Ablation electrode-tissue contact has b... more Effect of Ablation Electrode Contact Force. Introduction: Ablation electrode-tissue contact has been shown to be an important determinant of lesion size and safety during nonirrigated ablation but little data are available during irrigated ablation. We aimed to determine the importance of contact force during irrigated-tip ablation. Methods and Results: Freshly excised hearts from 11 male pigs were perfused and superfused using fresh, heparinized, oxygenated swine blood in an ex vivo model. One-minute ablations were placed using one of 3 different power control strategies (impedance control-15 target impedance drop, and 20 W or 30 W fixed power) and 3 different contact forces (2 g, 20 g, and 60 g) to give a grid of 9 ablation groups. The force sensing catheter (Tacticath TM , Endosense SA) was irrigated at 17 mL/min for all of the ablations. Of a total 101 ablations, no thrombus formation was noted but popping was seen in 17 lesions. The lesion depth and incidence of pops was 5.0 ± 1.3 mm /0%, 5.0 ± 1.6 mm /10% and 6.7 ± 2.5 mm /45% for the 15 , 20 W, and 30 W groups (P < 0.01), respectively, and 4.4 ± 1.8 mm /3%, 5.8 ± 1.6 mm /17% and 6.6 ± 2.0 mm /37% for the 2 g, 20 g, and 60 g groups, respectively (P < 0.01). The impedance drop in the first 5 seconds was significantly correlated to catheter contact force: 9.7 ± 9.9 , 22.3 ± 11.0 , and 41.7 ± 22.1 , respectively, for the 2 g, 20 g, and 60 g groups (Pearson's r = 0.65, P < 0.01). Conclusion: Catheter contact force has an important impact on both ablation lesion size and the incidence of pops.

Circulation, Sep 8, 2015

Background-Contact force (CF) is a major determinant of lesion size and transmurality and has the... more Background-Contact force (CF) is a major determinant of lesion size and transmurality and has the potential to improve efficacy of atrial fibrillation ablation. This study sought to evaluate the safety and effectiveness of a novel irrigated radiofrequency ablation catheter that measures real-time CF in the treatment of patients with paroxysmal atrial fibrillation. Methods and Results-A total of 300 patients with symptomatic, drug-refractory, paroxysmal atrial fibrillation were enrolled in a prospective, multicenter, randomized, controlled trial and randomized to radiofrequency ablation with either a novel CF-sensing catheter or a non-CF catheter (control). The primary effectiveness end point consisted of acute electrical isolation of all pulmonary veins and freedom from recurrent symptomatic atrial arrhythmia off all antiarrhythmic drugs at 12 months. The primary safety end point included device-related serious adverse events. End points were powered to show noninferiority. All pulmonary veins were isolated in both groups. Effectiveness was achieved in 67.8% and 69.4% of subjects in the CF and control arms, respectively (absolute difference, −1.6%; lower limit of 1-sided 95% confidence interval, −10.7%; P=0.0073 for noninferiority). When the CF arm was stratified into optimal CF (≥90% ablations with ≥10 g) and nonoptimal CF groups, effectiveness was achieved in 75.9% versus 58.1%, respectively (P=0.018). The primary safety end point occurred in 1.97% and 1.40% of CF patients and control subjects, respectively (absolute difference, 0.57%; upper limit of 1-sided 95% confidence interval, 3.61%; P=0.0004 for noninferiority). Conclusions-The CF ablation catheter met the primary safety and effectiveness end points. Additionally, optimal CF was associated with improved effectiveness.

Circulation-arrhythmia and Electrophysiology, Apr 1, 2013

Background-Pulmonary vein isolation is the most prevalent approach for catheter ablation of parox... more Background-Pulmonary vein isolation is the most prevalent approach for catheter ablation of paroxysmal atrial fibrillation. Long-term success of the procedure is diminished by arrhythmia recurrences occurring predominantly because of reconnections in previously isolated pulmonary veins. The aim of the EFFICAS I multicenter study was to demonstrate the correlation between contact force (CF) parameters during initial procedure and the incidence of isolation gaps (gap) at 3-month follow-up. Method and Results-A radiofrequency ablation catheter with integrated CF sensor (TactiCath, Endosense, Geneva, Switzerland) was used to perform pulmonary vein isolation in 46 patients with paroxysmal atrial fibrillation. During the ablation procedure, the operator was blinded to CF information. At follow-up, an interventional diagnostic procedure was performed to assess gap location as correlated to index procedure ablation parameters. At follow-up, 65% (26/40) of patients showed ≥1 gaps. Ablations with minimum Force-Time Integral (FTI) <400 gs showed increased likelihood for reconnection (P<0.001). Reconnection correlated strongly with minimum CF (P<0.0001) and minimum FTI (P=0.0007) at the site of gap. Gap occurrence showed a strong trend with lower average CF and average FTI. CF and FTI are generally higher on the right side, although the left anterior segment presents a unique challenge to achieve stable position with good CF. Conclusions-Minimum CF and minimum FTI values are strong predictors of gap formation. Optimal CF parameter recommendations are a target CF of 20 g and a minimum FTI of 400 gs for each new lesion. (Circ Arrhythm Electrophysiol. 2013;6:327-333.

Physics in Medicine and Biology, 1994

Circulation, Nov 22, 2011

Objectives Results of the EFFICAS I study illustrate that in patients with paroxysmal atrial fibr... more Objectives Results of the EFFICAS I study illustrate that in patients with paroxysmal atrial fibrillation (PAF) undergoing pulmonary vein isolation (PVI), ablation using low Force-Time Integral (FT...

Journal of Cardiovascular Electrophysiology, Nov 8, 2013

Left Atrial Scar Formation After Contact Force-Guided AF Ablation. Background: Catheter contact f... more Left Atrial Scar Formation After Contact Force-Guided AF Ablation. Background: Catheter contact force (CF) is an important determinant of radiofrequency (RF) lesion quality during pulmonary vein isolation (PVI). Late gadolinium enhancement (LGE) magnetic resonance imaging (MRI) allows good visualization of ablation lesions. Objective: This study describes a new technique to examine the relationship between CF during RF delivery and LGE signal intensity (SI) following PVI. Methods: Six patients underwent PVI for paroxysmal AF using a CF-sensing catheter and following preprocedural MRI. During ablation, CF-time integral (FTI) and position was documented for each RF application. All patients underwent repeat LGE MRI 3 months later. The LGE SIs were projected onto a MRI-derived 3-dimensional left atrial (LA) shell and a CF map was generated on the same shell. The entire LA surface was divided into 5 mm 2 segments. Force and LGE maps were fused and compared for each 5 mm 2 zone. An effective lesion was defined when MRI-defined scar occupied >90% of a 5 mm 2 analysis zone. Results: Acute PVI was achieved in 100%. Two hundred sixty-eight RF lesions were tagged on the LA shells and given a lesion-specific FTI. Increasing FTI correlated with increased LGE SI, which was greater when the FTI was >1,200 gs. Below an FTI of 1,200 gs, an increment in the FTI resulted in only a small increment in scar, whereas above 1,200 gs an increment in the FTI resulted in a large change of scar. Conclusion: There is a correlation between FTI and LGE SI in MRI following AF ablation. Real-time FTI maps are feasible and may prevent inadequate lesion formation.

Physics in Medicine and Biology, 1994

Springer eBooks, 2000

Background-In patients with atrial fibrillation, intracardiac atrial defibrillation causes discom... more Background-In patients with atrial fibrillation, intracardiac atrial defibrillation causes discomfort. An easily applicable, short-acting analgesic and anxiolytic drug would increase acceptability of this new treatment mode. Methods and Results-In a double-blind, placebo-controlled manner, the effect of intranasal butorphanol, an opioid, was evaluated in 47 patients with the use of a step-up internal atrial defibrillation protocol (stage I). On request, additional butorphanol was administered and the step-up protocol continued (stage II). Thereafter, if necessary, patients were intravenously sedated (stage III). After each shock, the McGill Pain Questionnaire was used to obtain a sensory (S), affective (A), evaluative (E), and total (T) pain rating index (PRI) and a visual analogue scale analyzing pain (VAS-P) and fear (VAS-F). For every patient, the slope of each pain or fear parameter against the shock number was calculated and individual slopes were averaged for the placebo and butorphanol group. All patients were cardioverted at a mean threshold of 4.4Ϯ3.3 J. Comparing both patient groups for stage II, the mean slopes for PRI-T (Pϭ0.0099), PRI-S (Pϭ0.019), and PRI-E (Pϭ0.015) became significantly lower in the butorphanol group than in the placebo group. Comparing patients who received the same shock intensity ending stage I and going to stage II, in those patients randomized to placebo the mean VAS-P (Pϭ0.023), PRI-T (Pϭ0.029), PRI-S (Pϭ0.030), and PRI-E (Pϭ0.023) became significantly lower after butorphanol administration. Conclusions-During a step-up internal atrial defibrillation protocol, intranasal butorphanol decreased or stabilized the value of several pain variables and did not affect fear. Of the 3 qualitative components of pain, only the affective component was not influenced by butorphanol. The PRI evaluated pain more accurately than the VAS. (Circulation.

Journal of Cardiovascular Electrophysiology, Jun 1, 1998

Electrode Length for Atrial Deflbrillation. Introduction: Catheter-based electrodes have heen use... more Electrode Length for Atrial Deflbrillation. Introduction: Catheter-based electrodes have heen used previously to terminate episodes of atrial flhrillation in animals and man. Typically, these electrodes span 6 to 7 cm, and lowest energy requirements are achieved when these electrodes are positioned in the distal coronary sinus and in the right atrium. The purpose of this study was to evaluate the use of longer electrode lengths for atrial deflbrillation. Methods and Results: In 15 patients, two decapolar catheters were inserted, one into the distal coronary sinus and one in the right atrium. To provide longer electrodes lengths, a third catheter was inserted and alternated positioned in the right atrium or coronary sinus. A 6-cm electrode span was ohtained by using the distal 8 rings on the coronary sinus catheter or 8 consecutive electrodes on the right atrial catheter and increased from 6 to 11 cm by connecting 5 consecutive, nonoverlapping rings of the third catheter with the 10 rings of the initial right atrial or coronary sinus catheter. Atrial defihrillation thresholds were determined twice, in a randomized order, in each patient for each of the three combinations of electrode lengths. All 15 patients could he successfully converted to sinus rhythm without complications; however, one patient could be converted reproducihiy with only 2 of the 3 electrode combinations. Mean thresholds were 306 ± 102 V, 5.9 ± 4.0 J for the 6 cm/6 cm electrode length comhination with an impedance of 72 ± 18 U. For the electrode combination using the U-cm electrode in the right atrium, the deHhrillation threshold was 296 ± 107 V, 5.8 ± 3.9 J with an impedance of 61 ± 17 SI and was 294 ± 91 V, 5.6 ± 3.6 J with an impedance of 55 ± 11 n for the 11-cm electrode in the coronary sinus. There were no .significant differences in defihrillation voltage or energy (P > 0.05) associated with the longer electrode lengths; however, the longer electrode lengths did significantly lower shock impedance (P < 0.05). Conclusion: The use of longer electrodes, when using the right atrium to coronary sinus shock vector, does not lower the defibrillation requirements for restoration of sinus rhythm.

Heart Rhythm, 2012

OBJECTIVES The aim of this multicenter study was to evaluate the device-and procedure-related saf... more OBJECTIVES The aim of this multicenter study was to evaluate the device-and procedure-related safety of a novel force-sensing radiofrequency (RF) ablation catheter capable of measuring the real-time contact force (CF) and to present CF data and its possible implications on patient safety. BACKGROUND The clinical outcome of RF ablation for the treatment of cardiac arrhythmias may be affected by the CF between the catheter tip and the tissue. Insufficient CF may result in an ineffective lesion, whereas excessive CF may result in complications. METHODS Seventy-seven patients (43 with right-sided supraventricular tachycardia [SVT] and 34 with atrial fibrillation [AF]) received percutaneous ablation with the novel studied catheter. The CF applied and safety events related to the procedure were reported. RESULTS CF values at mapping ranged from 8 Ϯ 8 to 60 Ϯ 35 g and from 12 Ϯ 10 to 39 Ϯ 29 g in the SVT group and the LA group, respectively, showing a significant interinvestigator variability (P Ͻ .0001). High transient CFs (Ͼ100 g) were noted in 27 patients (79%) of the LA group. One device-related complication (tamponade, 3%) occurred in the AF group.

Heart Rhythm, Nov 1, 2012

Journal of Cardiovascular Electrophysiology, 2010

Effect of Ablation Electrode Contact Force. Introduction: Ablation electrode-tissue contact has b... more Effect of Ablation Electrode Contact Force. Introduction: Ablation electrode-tissue contact has been shown to be an important determinant of lesion size and safety during nonirrigated ablation but little data are available during irrigated ablation. We aimed to determine the importance of contact force during irrigated-tip ablation. Methods and Results: Freshly excised hearts from 11 male pigs were perfused and superfused using fresh, heparinized, oxygenated swine blood in an ex vivo model. One-minute ablations were placed using one of 3 different power control strategies (impedance control-15 target impedance drop, and 20 W or 30 W fixed power) and 3 different contact forces (2 g, 20 g, and 60 g) to give a grid of 9 ablation groups. The force sensing catheter (Tacticath TM , Endosense SA) was irrigated at 17 mL/min for all of the ablations. Of a total 101 ablations, no thrombus formation was noted but popping was seen in 17 lesions. The lesion depth and incidence of pops was 5.0 ± 1.3 mm /0%, 5.0 ± 1.6 mm /10% and 6.7 ± 2.5 mm /45% for the 15 , 20 W, and 30 W groups (P < 0.01), respectively, and 4.4 ± 1.8 mm /3%, 5.8 ± 1.6 mm /17% and 6.6 ± 2.0 mm /37% for the 2 g, 20 g, and 60 g groups, respectively (P < 0.01). The impedance drop in the first 5 seconds was significantly correlated to catheter contact force: 9.7 ± 9.9 , 22.3 ± 11.0 , and 41.7 ± 22.1 , respectively, for the 2 g, 20 g, and 60 g groups (Pearson's r = 0.65, P < 0.01). Conclusion: Catheter contact force has an important impact on both ablation lesion size and the incidence of pops.

Circulation, Sep 8, 2015

Background-Contact force (CF) is a major determinant of lesion size and transmurality and has the... more Background-Contact force (CF) is a major determinant of lesion size and transmurality and has the potential to improve efficacy of atrial fibrillation ablation. This study sought to evaluate the safety and effectiveness of a novel irrigated radiofrequency ablation catheter that measures real-time CF in the treatment of patients with paroxysmal atrial fibrillation. Methods and Results-A total of 300 patients with symptomatic, drug-refractory, paroxysmal atrial fibrillation were enrolled in a prospective, multicenter, randomized, controlled trial and randomized to radiofrequency ablation with either a novel CF-sensing catheter or a non-CF catheter (control). The primary effectiveness end point consisted of acute electrical isolation of all pulmonary veins and freedom from recurrent symptomatic atrial arrhythmia off all antiarrhythmic drugs at 12 months. The primary safety end point included device-related serious adverse events. End points were powered to show noninferiority. All pulmonary veins were isolated in both groups. Effectiveness was achieved in 67.8% and 69.4% of subjects in the CF and control arms, respectively (absolute difference, −1.6%; lower limit of 1-sided 95% confidence interval, −10.7%; P=0.0073 for noninferiority). When the CF arm was stratified into optimal CF (≥90% ablations with ≥10 g) and nonoptimal CF groups, effectiveness was achieved in 75.9% versus 58.1%, respectively (P=0.018). The primary safety end point occurred in 1.97% and 1.40% of CF patients and control subjects, respectively (absolute difference, 0.57%; upper limit of 1-sided 95% confidence interval, 3.61%; P=0.0004 for noninferiority). Conclusions-The CF ablation catheter met the primary safety and effectiveness end points. Additionally, optimal CF was associated with improved effectiveness.

Circulation-arrhythmia and Electrophysiology, Apr 1, 2013

Background-Pulmonary vein isolation is the most prevalent approach for catheter ablation of parox... more Background-Pulmonary vein isolation is the most prevalent approach for catheter ablation of paroxysmal atrial fibrillation. Long-term success of the procedure is diminished by arrhythmia recurrences occurring predominantly because of reconnections in previously isolated pulmonary veins. The aim of the EFFICAS I multicenter study was to demonstrate the correlation between contact force (CF) parameters during initial procedure and the incidence of isolation gaps (gap) at 3-month follow-up. Method and Results-A radiofrequency ablation catheter with integrated CF sensor (TactiCath, Endosense, Geneva, Switzerland) was used to perform pulmonary vein isolation in 46 patients with paroxysmal atrial fibrillation. During the ablation procedure, the operator was blinded to CF information. At follow-up, an interventional diagnostic procedure was performed to assess gap location as correlated to index procedure ablation parameters. At follow-up, 65% (26/40) of patients showed ≥1 gaps. Ablations with minimum Force-Time Integral (FTI) <400 gs showed increased likelihood for reconnection (P<0.001). Reconnection correlated strongly with minimum CF (P<0.0001) and minimum FTI (P=0.0007) at the site of gap. Gap occurrence showed a strong trend with lower average CF and average FTI. CF and FTI are generally higher on the right side, although the left anterior segment presents a unique challenge to achieve stable position with good CF. Conclusions-Minimum CF and minimum FTI values are strong predictors of gap formation. Optimal CF parameter recommendations are a target CF of 20 g and a minimum FTI of 400 gs for each new lesion. (Circ Arrhythm Electrophysiol. 2013;6:327-333.

Physics in Medicine and Biology, 1994

Circulation, Nov 22, 2011

Objectives Results of the EFFICAS I study illustrate that in patients with paroxysmal atrial fibr... more Objectives Results of the EFFICAS I study illustrate that in patients with paroxysmal atrial fibrillation (PAF) undergoing pulmonary vein isolation (PVI), ablation using low Force-Time Integral (FT...

Journal of Cardiovascular Electrophysiology, Nov 8, 2013

Left Atrial Scar Formation After Contact Force-Guided AF Ablation. Background: Catheter contact f... more Left Atrial Scar Formation After Contact Force-Guided AF Ablation. Background: Catheter contact force (CF) is an important determinant of radiofrequency (RF) lesion quality during pulmonary vein isolation (PVI). Late gadolinium enhancement (LGE) magnetic resonance imaging (MRI) allows good visualization of ablation lesions. Objective: This study describes a new technique to examine the relationship between CF during RF delivery and LGE signal intensity (SI) following PVI. Methods: Six patients underwent PVI for paroxysmal AF using a CF-sensing catheter and following preprocedural MRI. During ablation, CF-time integral (FTI) and position was documented for each RF application. All patients underwent repeat LGE MRI 3 months later. The LGE SIs were projected onto a MRI-derived 3-dimensional left atrial (LA) shell and a CF map was generated on the same shell. The entire LA surface was divided into 5 mm 2 segments. Force and LGE maps were fused and compared for each 5 mm 2 zone. An effective lesion was defined when MRI-defined scar occupied >90% of a 5 mm 2 analysis zone. Results: Acute PVI was achieved in 100%. Two hundred sixty-eight RF lesions were tagged on the LA shells and given a lesion-specific FTI. Increasing FTI correlated with increased LGE SI, which was greater when the FTI was >1,200 gs. Below an FTI of 1,200 gs, an increment in the FTI resulted in only a small increment in scar, whereas above 1,200 gs an increment in the FTI resulted in a large change of scar. Conclusion: There is a correlation between FTI and LGE SI in MRI following AF ablation. Real-time FTI maps are feasible and may prevent inadequate lesion formation.

Physics in Medicine and Biology, 1994