Acoustic Radiation Force Impulse Imaging Visualization of Chronic Atrial Fibrosis and Ablation Lesions and Fibrosis During Catheter Ablation for Atrial Flutter (original) (raw)
Related papers
Heart Rhythm, 2012
Background: Arrhythmia recurrence after cardiac radiofrequency ablation (RFA) for atrial fibrillation has been linked to conduction through discontinuous lesion lines. Intraprocedural visualization and corrective ablation of lesion line discontinuities could decrease postprocedure atrial fibrillation recurrence. Intracardiac acoustic radiation force impulse (ARFI) imaging is a new imaging technique that visualizes RFA lesions by mapping the relative elasticity contrast between compliant-unablated and stiff RFA-treated myocardium. Objective: To determine whether intraprocedure ARFI images can identify RFA-treated myocardium in vivo. Methods: In 8 canines, an electroanatomical mapping–guided intracardiac echo catheter was used to acquire 2-dimensional ARFI images along right atrial ablation lines before and after RFA. ARFI images were acquired during diastole with the myocardium positioned at the ARFI focus (1.5 cm) and parallel to the intracardiac echo transducer for maximal and uniform energy delivery to the tissue. Three reviewers categorized each ARFI image as depicting no lesion, noncontiguous lesion, or contiguous lesion. For comparison, 3 separate reviewers confirmed RFA lesion presence and contiguity on the basis of functional conduction block at the imaging plane location on electroanatomical mapping activation maps. Results: Ten percent of ARFI images were discarded because of motion artifacts. Reviewers of the ARFI images detected RFA-treated sites with high sensitivity (95.7%) and specificity (91.5%). Reviewer identification of contiguous lesions had 75.3% specificity and 47.1% sensitivity. Conclusions: Intracardiac ARFI imaging was successful in identifying endocardial RFA treatment when specific imaging conditions were maintained. Further advances in ARFI imaging technology would facilitate a wider range of imaging opportunities for clinical lesion evaluation.
Journal of cardiovascular electrophysiology, 2014
Visual confirmation of radiofrequency ablation (RFA) lesions during clinical cardiac ablation procedures could improve procedure efficacy, safety, and efficiency. It was previously shown that acoustic radiation force impulse (ARFI) imaging can identify RFA lesions in vitro and in vivo in an animal model. This is the "first-in-human" feasibility demonstration of intracardiac ARFI imaging of RFA lesions in patients undergoing catheter ablation for atrial flutter (AFL) or atrial fibrillation (AF). Patients scheduled for right atrial (RA) ablation for AFL or left atrial (LA) ablation for drug refractory AF were eligible for imaging. Diastole-gated intracardiac ARFI images were acquired using one of two equipment configurations: (1) a Siemens ACUSON S2000™ ultrasound scanner and 8/10Fr AcuNav™ ultrasound catheter, or (2) a CARTO 3™ integrated Siemens SC2000™ and 10Fr SoundStar™ ultrasound catheter. A total of 11 patients (AFL = 3; AF = 8) were imaged. ARFI images were acquired ...
Journal of …, 2010
Introduction: Lesion placement and transmurality are critical factors in the success of cardiac transcatheter radiofrequency ablation (RFA) treatments for supraventricular arrhythmias. This study investigated the capabilities of catheter transducer based acoustic radiation force impulse (ARFI) ultrasound imaging for quantifying ablation lesion dimensions. Methods and Results: RFA lesions were created in vitro in porcine ventricular myocardium and imaged with an intracardiac ultrasound catheter transducer capable of acquiring spatially registered B-mode and ARFI images. The myocardium was sliced along the imaging plane and photographed. The maximum ARFI-induced displacement images of the lesion were normalized and spatially registered with the photograph by matching the surfaces of the tissue in the B-mode and photographic images. The lesion dimensions determined by a manual segmentation of the photographed lesion based on the visible discoloration of the tissue were compared to automatic segmentations of the ARFI image using 2 different calculated thresholds. ARFI imaging accurately localized and sized the lesions within the myocardium. Differences in the maximum lateral and axial dimensions were statistically below 2 mm and 1 mm, respectively, for the 2 thresholding methods, with mean percent overlap of 68.7 ± 5.21% and 66.3 ± 8.4% for the 2 thresholds used. Conclusion: ARFI imaging is capable of visualizing myocardial RFA lesion dimensions to within 2 mm in vitro. Visualizing lesions during transcatheter cardiac ablation procedures could improve the success of the treatment by imaging lesion line discontinuity and potentially reducing the required number of ablation lesions and procedure time. (J Cardiovasc Electrophysiol, Vol. 21, pp. 557-563, May 2010)
Catheter Ablation Lesion Visualization With Intracardiac Strain Imaging in Canines and Humans
IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
Catheter ablation is a common treatment for arrhythmia, but can fail if lesion lines are non-contiguous. Identification of gaps and non-transmural lesions can reduce the likelihood of treatment failure and recurrent arrhythmia. Intracardiac myocardial elastograph is a strain imaging technique that provides visualization of the lesion line. Lesion size estimation and gap resolution was evaluated in an open chest canine model (n=3), and clinical feasibility was investigated in patients undergoing ablation to treat typical cavotricuspid isthmus atrial flutter (n=5). A lesion line consisting of three lesions and two gaps was generated in each canine left ventricle via epicardial ablation. One lesion was generated in one canine right ventricle. Average lesion and gap areas were measured with high agreement (33 ± 14 mm 2 and 30 ± 15 mm 2 , respectively) when compared against gross pathology (34 ± 19 mm 2 and 26 ± 11 mm 2 , respectively). Gaps as small as 11 mm 2 (3.6 mm on epicardial surface) were identifiable. Absolute error and relative error in estimated lesion area were 9.3 ± 8.4 mm 2 and 31 ± 34 %; error in estimated gap area was 11 ± 9.0 mm 2 and 40 ± 29 %. Flutter patients were imaged throughout the procedure. Strain was shown to be capable of differentiating between baseline and after ablation completion as confirmed by conduction block. In all patients, strain decreased in the cavotricuspid isthmus after ablation (mean paired difference of-17 ± 11 %, p < 0.05). IME could potentially become a useful ablation monitoring tool in the clinic.
Radiofrequency Ablation Lesions Contrast in Intracardiac Acoustic Radiation Force Impulse Images of
We have previously shown that intracardiac acoustic radiation force impulse (ARFI) imaging visualizes tissue stiffness changes caused by radiofrequency ablation (RFA). The objectives of this in vivo study were to (1) quantify measured ARFI-induced displacements in RFA lesion and unablated myocardium and (2) calculate the lesion contrast (C) and contrast-to-noise ratio (CNR) in two-dimensional ARFI and conventional intracardiac echo images. In eight canine subjects, an ARFI imaging-electroanatomical mapping system was used to map right atrial ablation lesion sites and guide the acquisition of ARFI images at these sites before and after ablation. Readers of the ARFI images identified lesion sites with high sensitivity (90.2%) and specificity (94.3%) and the average measured ARFI-induced displacements were higher at unablated sites (11.23 ± 1.71 µm) than at ablated sites (6.06 ± 0.94 µm). The average lesion C (0.29 ± 0.33) and CNR (1.83 ± 1.75) were significantly higher for ARFI images than for spatially registered conventional B-mode images (C = −0.03 ± 0.28, CNR = 0.74 ± 0.68).
Contrast in Intracardiac Acoustic Radiation Force Impulse Images of Radiofrequency Ablation Lesions
Ultrasonic Imaging, 2014
We have previously shown that intracardiac acoustic radiation force impulse (ARFI) imaging visualizes tissue stiffness changes caused by radiofrequency ablation (RFA). The objectives of this in vivo study were to (1) quantify measured ARFI-induced displacements in RFA lesion and unablated myocardium and (2) calculate the lesion contrast (C) and contrast-to-noise ratio (CNR) in two-dimensional ARFI and conventional intracardiac echo images. In eight canine subjects, an ARFI imaging-electroanatomical mapping system was used to map right atrial ablation lesion sites and guide the acquisition of ARFI images at these sites before and after ablation. Readers of the ARFI images identified lesion sites with high sensitivity (90.2%) and specificity (94.3%) and the average measured ARFI-induced displacements were higher at unablated sites (11.23 ± 1.71 µm) than at ablated sites (6.06 ± 0.94 µm). The average lesion C (0.29 ± 0.33) and CNR (1.83 ± 1.75) were significantly higher for ARFI images than for spatially registered conventional B-mode images (C = −0.03 ± 0.28, CNR = 0.74 ± 0.68).
MRI Assessment of Ablation-Induced Scarring in Atrial Fibrillation: Analysis from the DECAAF Study
Journal of Cardiovascular Electrophysiology, 2015
Background: There is limited knowledge on the extent and location of scarring that results from catheter ablation and its role in suppressing atrial fibrillation (AF). We examined the effect of atrial fibrosis and ablation induced scarring on catheter ablation outcomes in AF. Methods: We conducted a prospective multicenter study that enrolled 329 AF patients presenting for catheter ablation. Delayed enhancement magnetic resonance imaging (DE-MRI) of the left atrium was obtained pre-ablation. Scarring was evaluated in 177 patients with a DE-MRI scan obtained 90 days post-ablation. We evaluated residual fibrosis, defined as pre-ablation atrial fibrosis not covered by ablation scar. The primary outcome was freedom from recurrent atrial arrhythmia. Results: In the analysis cohort of 177 patients, pre-ablation fibrosis was 18.7±8.7% of the atrial wall. Ablation aimed at pulmonary vein (PV) isolation was performed in 163 patients (92.1%). Ablation-induced scar averaged 10.6±4.4% of the atrial wall. Scarring completely encircled all 4 PVs only in 12 patients (7.3%). Residual fibrosis was calculated at 15.8 ± 8.0%. At 325 days follow-up 35% of patients experienced recurrent arrhythmia. Multivariable Cox proportional hazards models demonstrated that baseline atrial fibrosis (HR and 95%
Journal of Cardiovascular Electrophysiology, 2013
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.
F1000 - Post-publication peer review of the biomedical literature, 2011
Introduction-Left atrial (LA) fibrosis and ablation related scarring are major predictors of success in rhythm control of atrial fibrillation (AF). We used delayed enhancement MRI (DE-MRI) to stratify AF patients based on pre-ablation fibrosis and also to evaluate ablation-induced scarring in order to identify predictors of a successful ablation. Methods and Results-One hundred and forty-four patients were staged by percent of fibrosis quantified with DE-MRI, relative to the LA wall volume: minimal or Utah stage 1; <5%, mild or Utah stage 2; 5-20%, moderate or Utah stage 3; 20-35%, and extensive or Utah stage 4; >35%. All patients underwent pulmonary vein (PV) isolation and posterior wall and septal debulking. Overall, LA scarring was quantified and PV antra were evaluated for circumferential scarring 3 months post ablation. LA scarring post ablation was comparable across the 4 stages. Most patients had either no (36.8%) or 1 PV (32.6%) antrum circumferentially scarred. Forty-two patients (29%) had recurrent AF over 283 ± 167 days. No recurrences were noted in Utah stage 1. Recurrence was 28% in Utah stage 2, 35% in Utah stage 3, and 56% in Utah stage 4. Recurrence was predicted by circumferential PV scarring in Utah stage 2 and by overall LA wall scarring in Utah stage 3. No recurrence predictors were identified in Utah stage 4. Conclusions-Circumferential PV antral scarring predicts ablation success in mild LA fibrosis, while posterior wall and septal scarring is needed for moderate fibrosis. This may help select the proper candidate and strategy in catheter ablation of AF.