Intracardiac Echocardiography Imaging Research Articles

The intracardiac echocardiographic findings during rewarming using catheter-based cryoablation

Abstract Introduction Cryoablation unlike radiofrequency ablation (RFA) does not damage the endothelium and lining and causes less physical damage, and the mechanisms remain unclear. The increased myocardial echogenicity (iME) observed by intracardiac echocardiography (ICE) during RFA has been reported as the ablation indicator. Purpose To evaluate the ICE findings during ablation using catheter-based cryoablation. Methods In an extra vivo experiment, we set the bovine myocardium to 36°C in a constant temperature bath and experimented on a water tank that generated a non-pulsatile flow. Catheter-based cryoablation was applied to the bovine myocardium at -80 degrees for 240 seconds. The ICE images were evaluated using ViewFlex Xtra during catheter-based cryoablation. Results Macroscopic change (Figure 1): Four seconds after the start of cooling, a thin film of ice began to form between the myocardium and the catheter, and after 7 seconds, the tip of the catheter was covered with ice and the surface of the myocardium was covered with ice. After that, it grew rapidly and an ice ball was formed. There was no change after 18 seconds of cooling. ICE findings (Figure 2): 4 seconds after cooling started, the ME around the catheter tip began to increase, and the ME gradually increased with flickering. The iME stopped after cooling down for 18 seconds and did not change after that. Immediately after stopping cooling, severe flickering occurred and the area of iME began to shrink. The ME gradually returned to its original state with slight bubbles from the central ablation site. Macroscopic change and ICE findings were reproducibly confirmed. Myocardial findings after ablation: The area of cooling was discernible, but the color difference from the surrounding area was not obvious. Conclusions The catheter-based cryoablation ablation shows the severest change detected by ICE immediately after stopping cooling. In addition to tissue damage during the freezing stage, the rewarming may be more associated with tissue damage.

Left bundle branch area pacing guided by intracardiac echocardiography imaging

Left bundle branch area pacing guided by intracardiac echocardiography imaging

Ventricular tachycardia mapping and ablation using MIXture of well-established approaches. The MIX-VT study

Abstract Introduction Ablation for ventricular tachycardia (VT) is still challenging despite impressive technology development, especially in mid- or low-volume centers. The most frequently used approach is homogenization of scar area responsible for VT, combined with standard electrophysiological (EP) approaches such as VT inducibility and mapping. However, in real life long-term efficacy of VT ablation in such centers does not exceed 50%. We hypothesized that an approach consisting of the mixture of various well-established parameters would be more effective than scar homogenization and VT non-inducibility as the endpoints. Purpose To compare the outcome of VT ablation using the standard approach (scar homogenization) and a more complex approach, called the MIX-VT protocol, using late potential mapping + pace mapping with rapid change of VT morphology to localize the critical isthmus + core isolation. All procedures were performed using the 3D mapping system, Pentaray mapping catheter, Smart-Touch ablation catheter and intracardiac echocardiography (ICE). Methods 48 consecutive patients (41 male, mean age 71.5 years) with ischemic cardiopathy referred for urgent VT ablation were included: 23 patients underwent "standard" VT ablation between December 2018 and December 2019, whereas the next 25 patients underwent ablation using the MIX-VT protocol between January 2020 and December 2020. First step in the MIX-VT group was to perform ICE imaging of the scar area from the right ventricle. Next, left ventricular maps were created during rhythm at which spontaneous VT occurred (sinus or paced). Areas of late potentials were identified to localize the critical isthmus where the abrupt change in the paced-QRS axis was seen. Finally, areas delineated by these two above-mentioned maneuvers where ablated in order to achieve core isolation (Figure 1). The patients were followed for 12 months in the outpatient clinic during ICD examination. The composite end-point for follow-up was VT recurrences terminated by anty-tachycardia pacing (ATP) or shock, or death. Results Clinical and demographic variables were similar between the two groups (Figure 2), except for a higher prevalence of diabetes mellites and number of previous ablations in the standard group (4/25 [16%] vs 10/23 [43%], p=0.03 and 2/24 vs 8/23 [34.8], p=0.03, respectively). Three patients from the MixVT group and one patient from the standard group were lost to follow-up. During follow-up, VT recurrences were significantly less frequent in the MIX-VT group (3/22 [13.6] vs 10/22 [45.4]. p=0.02. It was mostly driven by less ATP therapy. (Figure 2). One patient from the standard approach groups died. Conclusion Ablation for VT in low- or medium volume centers using the combination of well-established various EP approaches resulted in the improvement in overall survival and arrythmia-free survival. The presented approach does not involve additional resource utilization.

3D Navigation and Intraprocedural Intracardiac Echocardiography Imaging for Tricuspid Transcatheter Edge-to-Edge Repair

3D Navigation and Intraprocedural Intracardiac Echocardiography Imaging for Tricuspid Transcatheter Edge-to-Edge Repair

Collateral coronary flow in the interventricular septum detected on intracardiac echocardiographic imaging

Collateral coronary flow in the interventricular septum detected on intracardiac echocardiographic imaging

Intramyocardial Hematoma During Catheter Ablation for Scar-Related Ventricular Tachycardia.

Intramural hematoma during ablation for scar-related ventricular tachycardia (VT) is a rare but life-threatening complication. The goal of this study was to describe the features and outcomes of intramural hematoma during ablation for scar-related VT. From 2010 to 2022, >3,514 ablations for ventricular arrhythmias were performed at 2 institutions. Four cases of intramural hematoma complicating VT ablation for scar-related VT were identified. Intraprocedural details, imaging data, and surgical notes were reviewed to create a recognizable pattern of events highlighting this complication. In 3 of 4 cases, intramural hematoma occurred during catheter ablation with an open irrigated 3.5mm tipped catheter using normal saline for irrigation. In one case, hematoma was noted after ablation using an investigational needle electrode catheter. The occurrence of a steam pop preceded detection of an expanding intramural hematoma in 3 cases. ST-segment elevation on electrocardiography was evident in 3 cases; intracardiac echocardiographic imaging detected the hematoma in all cases. Epicardial rupture and pericardial effusion requiring drainage occurred in 3 cases, whereas 1 hematoma was self-contained and did not require intervention. Surgical intervention was performed in 2 cases, with successful outcomes. One patient who was deemed not a surgical candidate died of progressive cardiogenic shock. Intramural hematoma during ablation for scar-related VT is a rare but potentially catastrophic complication that requires prompt recognition. Steam pops during ablation frequently precede the hematoma formation. Surgical intervention may be life-saving, although contained hematomas can occasionally be managed conservatively.

The Emerging Role of Intracardiac Echocardiography (ICE) in Left Atrial Appendage Closure (LAAC).

Intracardiac echocardiography (ICE) has emerged as a powerful imaging tool to guide percutaneous left atrial appendage closure (LAAC). Herein, we review an imaging protocol for ICE-guided LAAC and discuss the evidence for its use. Standardized imaging protocols have been proposed but have not been fully validated. ICE imaging yields similar procedural and clinical outcomes when compared to transesophageal echocardiography (TEE) to guide LAAC. Despite benefits of avoiding general anesthesia, TEE, and multiple physicians for LAAC procedures, ICE imaging remains under-utilized. Novel ICE catheters with 3D imaging capabilities may improve accuracy and efficiency of LAAC device implantation. ICE guidance is feasible, safe, and effective for LAAC. As the field evolves, further studies will be necessary to assess this technological advancement in imaging guidance.

Imaging Modality to Guide Left Atrial Appendage Closure: Current Status and Future Perspectives.

Atrial fibrillation (AF) is the most common cardiac arrhythmia in adults. The left atrial appendage (LAA) is the most likely source of thrombus formation in patients with non-valvular atrial fibrillation (NVAF). Left atrial appendage closure (LAAC) represents an effective alternative to NOAC in patients with NVAF. Expert consensus documents recommend intraprocedural imaging by means of either transesophageal echocardiography (TEE) or intracardiac echocardiography (ICE) in addition to standard fluoroscopy to guide LAAC. TEE-guided LAAC usually requires general anesthesia. The ICE technique is a "minimalist approach", without general anesthesia, but ICE imaging techniques are not yet simplified and standardize, and the ICE may result in inferior image quality compared with that of TEE. Another "minimalist approach" can be the use of ICE via the esophageal route (ICE-TEE), that jet is validated to identify the presence of LAA thrombi in patients and to perform other procedures. In our cath laboratory ICE-TEE to guide LAAC is used in some complex patients. Indeed, our single center experience suggests that ICE-TEE could be a good alternative imaging technique to guide LAAC procedure without general anesthesia.

Intracardiac echocardiographic imaging with a cartosound module for guidance of left atrial appendage closure: a comparative study with transesophageal echocardiographic imaging.

In most clinical trials, intracardiac echocardiography (ICE) has provided fewer views than the four standard views provided by transesophageal echocardiography (TEE) when assessing left atrial appendage closure (LAAC) devices. This study aimed to determine if ICE guided by the CartoSound system achieve adequate high-quality views and similar clinical outcomes as TEE during LAAC. This study prospectively enrolled 202 patients who underwent LAAC using either ICE (n = 69), TEE (n = 121), or a combination of ICE and TEE (n = 12) as the procedural imaging under local anesthesia. A novel multi-angled "FLAVOR" approach was used for assessment in the ICE group. ICE allowed visualization of the implanted devices in all patients at all proposed angles with long-axis views while two-dimensional (2D) TEE showed short-axis views in 1 or 2 angles in 24.2% of cases, which was more prevalent when the pulmonary ridge was covered by the occluder. In the combined ICE-TEE cohort, 2D-TEE failed to detect peri-device leak in 1 patient. The complication rates were similar between the ICE and TEE groups. Shorter fluoroscopy time, lower radiation dose and contrast usage were founded in the ICE group. At first TEE follow-up, the rate and degree of peri-device leak were similar between the ICE and TEE groups. A systematic ICE protocol using a CartoSound module to guide LAAC was reliable for comprehensive long-axis imaging assessment compared with 2D/3D TEE under local anesthesia with a shorter fluoroscopy time, lower radiation dose, and less use of contrast.

PO-04-045 HOW TO VISUALIZE BIPOLAR ABLATION CATHETERS ON 3D MAPPING FOR BIPOLAR RADIOFREQUENCY CATHETER ABLATION AND MINIMIZE FLUOROSCOPY

Bipolar radiofrequency catheter ablation (RFCA) strategy using two ablation catheters may require prolonged fluoroscopy time because of challenges with catheter positioning. Intracardiac echocardiographic images may only offer limited views to help maneuver both ablation catheters. To simultaneously visualize both ablation catheters on the 3D mapping system for localizing the ablation target and minimizing fluoroscopy. A bipolar RFCA system was set up with connections to the grounding pad and two distal pins connected to the distal electrodes of the THERMOCOOL SMARTTOUCH® SF ablation catheter (Biosense Webster) with 1-6-2mm spacing (Figure A). Case 1: A 51-year-old male with familial HCM presented with VT storm for which he was externally cardioverted. The patient underwent VT ablation during which the VT was localized to LV summit. Due to difficulty achieving transmural lesions with unipolar ablation, bipolar RFCA with two ablation catheters on posteroseptal RVOT and below the RCC was performed with successful elimination of the clinical VT. The distal 3rd and 4th electrodes on the second ablation catheter was connected to our bipolar circuit, which was visualized on CARTO® 3D mapping (Biosense Webster) (Figure B). Case 2: A 62-year-old male with a CRT-D for cardiac sarcoidosis and non-ischemic cardiomyopathy, and a recent endocardial VT ablation in the setting of VT storm presented with multiple ICD shocks. Patient underwent repeat ablation with further endocardial substrate modification and epicardial ablation. With the second ablation catheter on the epicardium, the distal 3rd and 4th electrodes were visualized, and the dome of the catheter tip was created on CARTO® (Figure C). The patient underwent an extensive endocardial and epicardial ablation but remained inducible with slower VT for which he underwent further heart transplant evaluation. Utilizing a novel bipolar RFCA set-up that allows visualization of both ablation catheters on the 3D mapping system may offer better target localization and less fluoroscopy exposure.

PO-04-016 FIRST REPORT OF LEADLESS PACEMAKER IMPLANTATION IN A PATIENT WITH BOTH A TRANSCATHETER TRICUPID VALVE REPAIR (TRICLIP) AND SURGICAL TRICUSPID VALVE ANNULOPLASTY

An increasing number of patients with valvular heart disease are undergoing novel structural valve interventions with subsequent need for pacemaker implantation. Leadless cardiac pacemakers (LCP) may be particularly suitable in patients with prior tricuspid valve interventions. However, the process of navigating previously repaired tricuspid valves (surgical or percutaneous) can be challenging. To our knowledge, implantation of an LCP in a patient with both surgical TV repair (annuloplasty) and transcatheter TV repair (TriClip, TTVr) has not been reported. In this case, intracardiac echocardiography (ICE) was used to navigate the LCP to its final implant position. To describe the feasibility of implanting an LCP in a patient with surgical and percutaneous tricuspid valve repairs, and the utility of ICE-guided implantation. N/A A 69 year old female with prior inferior vena cava (IVC) filter, percutaneous mitral valve repair (MitraClip) and transcatheter tricuspid valve repair (TriClip) underwent a BioBentall procedure with tricuspid valve repair (annuloplasty band). The existing clips were not removed at the time of surgery. She ultimately developed an indication for back-up ventricular pacing (intermittent high-degree AV block) and an LCP was recommended (Micra, Medtronic Inc., Minneapolis, MN). Under fluoroscopic guidance, the LCP introducer sheath (27 French outer diameter) was first traversed through the IVC filter into the right atrium. Then, using ICE to visualize the tricuspid valve and taking note of the clip position, the deflectable delivery system was maneuvered through the residual tricuspid valve orifice into the right ventricle while avoiding the clips via a superior and anterior approach. Positioning of the delivery system in the apical right ventricular septum in respect to the annuloplasty band and clips was confirmed on ICE imaging and fluoroscopy before and after deployment. LCP sensing, pacing threshold and impedance values were within normal limits. The severity of pre-existing moderate residual tricuspid regurgitation remained unchanged on follow up transthoracic echocardiography. Implantation of a leadless pacemaker after both transcatheter tricuspid valve repair and surgical tricuspid valve annuloplasty band is feasible. Steering through an anatomically challenging tricuspid valve neo-orifices can be performed safely and effectively under intracardiac echocardiography guidance.

PO-04-060 FOUND WITH SOUND: INTRACARDIAC ECHOCARDIOGRAPHY CORRELATED WITH MEDIUM-OUTPUT PACING TO AVOID PHRENIC NERVE INJURY WITH RIGHT ATRIAL ABLATION

Catheter ablation within the right atrium can be limited by proximity to the phrenic nerve and potential for hemi diaphragmatic paralysis. High output pacing is frequently employed to map phrenic position relative to endocardium, particularly in relation to the superior vena cava and the right superior pulmonary vein. The use of intracardiac echocardiography (ICE) in correlation with lower output pacing to rigorously map the course of the right phrenic nerve along the right atrium has not been previously described. We describe a case of incessant right atrial tachycardia successfully mapped and ablated close to the phrenic nerve using a combination of ICE imaging and medium-output pacing to rigorously map the phrenic nerve. n/a An 18-year-old man with incessant atrial tachycardia was referred for repeat ablation following unsuccessful attempt at ablation at an outside institution. Prior ablation was limited by proximity to the phrenic nerve and transient phrenic nerve palsy with cryoablation at the mid crista terminalis. Epicardial access to deflect the phrenic nerve was anticipated. Atrial tachycardia was mapped endocardially prior to obtaining epicardial access. An ICE catheter was advanced to the SVC and used to identify the phrenic nerve. The course of the phrenic nerve was rigorously mapped with ICE and integrated into the CARTO navigational system (Biosense Webster). Pacing along the course of the phrenic nerve was performed at 10 mA to further refine the course of the phrenic nerve within the SVC and right atrium. Regions in close anatomic proximity to the phrenic nerve with loss of pace-capture correlated with sites of physiologic effusion, where pericardial fluid was concentrated and separation of the phrenic nerve from the visceral epicardium was noted. After mapping the phrenic nerve, endocardial ablation of atrial tachycardia was successfully performed in the absence of phrenic nerve injury without the need for epicardial access. Phrenic nerve injury may be prevented by rigorous mapping of the phrenic nerve within the right atrium using intracardiac ultrasound with medium-output pacing.

MP-453087-3 REMOVAL OF A CHRONICALLY-IMPLANTED MICRA LEADLESS VENTRICULAR – SINGLE CENTER EXPERIENCE

Leadless cardiac pacemakers (LPs) are an effective and safe alternative to transvenous pacemakers for single-chamber ventricular pacing. However, the feasibility of retrieving and replacing chronically implanted LPs is not well understood. We report an unique single center series of chronically implanted MICRA TPS™ leadless pacemakers. Since 2014 there were 227 MICRA LP devices implanted successfully to the right ventricle (RV) position. In 8 patients with average time of 685 ± 373 days retrieval procedure was indicated. The main indication for LP extraction was: a) pacemaker syndrome; b) battery depletion (in two patients together with WiSE EBR left ventricle (LV) co-implant); c) needs to upgrade VVI pacing for resynchronization therapy with LV systolic dysfunction. In all 8 patients we used MICRA delivery catheter with single loop 7 mm snare inserted into the central lumen of the original delivery catheter. Besides fluoroscopy we guided the retrieval procedure with intracardiac echocardiography (ICE). The retrieval procedure was successful in 7 out of 8 petients (87,5%). Average time of the index retrieval procedure was 118 ± 27 minutes and average fluoroscopy time was 26.6 ± 10.5 minutes. In the case with retrieval procedure failure (348 days after implant) we couldn’t snare the docking bottom of the device. In rest of the cases where we were able to snare it and connect with the delivery catheter cap, we were able to reach the insertion of the LP to the tissue and apply contratraction force with 100% success. When we analysed ICE images, the LP retrieval failure was associated with massive tissue overgrow around the device capsule. In 6 patients new MICRA TPS™ LP was implanted with excellent pacing parameters and optimal sensing and impedance during the same procedure. In one patient we implanted CRT-D transvenous system due to LV dysfunction. This series demonstrates the feasibility of retrieval of even long-term chronically-implanted MICRA LPs. The dedicated retrieval system for LPs with anchors will be of interest when we can consider needs to exchange of LPs specifically in younger patients.

Visualization and mapping of the right phrenic nerve by intracardiac echocardiography during atrial fibrillation ablation.

This study aimed to evaluate the feasibility of real-time visualization and mapping of the right phrenic nerve (RPN) by using intracardiac echocardiography (ICE) during atrial fibrillation (AF) ablation. RPN injury is a complication associated with the ablation of AF. Multiple approaches are currently being used to prevent and detect RPN injuries. However, none of these approaches can directly visualize the RPN in real-time during the ablation procedure. The RPN was detected using ICE. The RPN and its adjacent structures were analysed. The relationship between the RPN's distance from the superior vena cava (SVC) and its pacing capture threshold was quantified. The safety of SVC isolation guided by the ICE-visualized RPN was evaluated. Thirty-eight people were enrolled in this study. The RPN was visualized by ICE in 92% of patients. It ran through the space between the SVC and the mediastinal pleura and had a 'straw'-like appearance upon ICE imaging. The course of the RPN was close to the SVC (minimum 1.0 ± 0.4 mm) and the right superior pulmonary vein (minimum 14.1 ± 7.3 mm). There was a positive linear correlation between the RPN's capture threshold and its distance from the SVC (Spearman's correlation coefficient = 0.728, < 0.001). SVC isolation was guided by the RPN; none of the patients developed an RPN injury. RPN can be visualized by ICE in most patients, thus providing a novel approach for the real-time detection of RPN during AF ablation.

Safety of continuous left atrial phased-array intracardiac echocardiography during left atrial ablation for atrial fibrillation.

Pulmonary vein (PV) isolation using radiofrequency ablation (RFA) to treat atrial fibrillation (AF) requires delivery of contiguous transmural lesions at the PV antra while avoiding injury to the esophagus. Continuous 2-dimensional phased-array intracardiac echocardiography (ICE) from within the left atrium (LA) can provide consistent high-resolution images of catheter tip contact and location during ablation. The purpose of this study was to compare near-term safety outcomes of therapeutic AF ablation with and without ICE imaging from within the LA. The study cohort included 590 consecutive patients undergoing RFA for AF including continuous ICE imaging during ablation from within either the right atrium (RA) or the LA. Subjects were followed prospectively, and periprocedural complications within 30 days were identified and recorded. All subjects had RA ICE imaging to guide transseptal catheterization. Ultrasound imaging from both RA and LA was used in 243 (41.2%). Respectively, the LA vs RA only imaging cohorts were comparable with respect to age (median 64 [interquartile range 57.4-71.2] years vs 64 [56.2-70.6] years; P = .425); history of hypertension (64.0% vs 67.2%; P = .421); diabetes mellitus (23.1% vs 19.4%; P = .268); previous cerebrovascular accident/transient ischemic attack (10.8% vs 8.4%; P = .331); and AF type (P = .241). There were no significant differences in major complications within 30 days between the 2 cohorts (P = .649) and no identified cases of esophageal or phrenic nerve injury or PV stenosis. Routine continuous LA ICE imaging seems to be safe and holds potential to facilitate lesion delivery during RFA for AF.

Abstract 14437: Safety of Fluoroless Radiofrequency Ablation for Atrial Fibrillation in Patients With Pre-Existing Cardiac Implantable Electronic Device

Introduction: Radiofrequency catheter ablation (RFA) for atrial fibrillation (AF) is being increasingly performed without fluoroscopy. There is limited experience in flouroless RFA for AF in patients with pre-existing cardiac implantable electronic devices (CIED). Hypothesis: The safety of Fluoroless RFA for AF in patients with pre-existing CIED is uncertain. Methods: In this single-center study, we retrospectively evaluated patients undergoing fluoroless RFA for AF with pre-existing CIED in situ. A total of two hundred and sixty-four (264) consecutive fluoroless RFA procedures for AF from 6/1/2019 to 5/2/2022 were evaluated. All procedures were performed with intracardiac echocardiography (ICE) support. We assessed rates of CIED-related complications and changes in lead parameters over 30 days of follow-up. Pre and post-ablation device interrogations were reviewed for interval changes and compared for any change in the device or lead parameters. Patients were tracked for any subsequent device malfunction. Results: Among 264 fluoroless AF ablations patients, 25 (9.5%) had pre-existing CIED (13 dual-chamber pacemakers, 4 dual-chamber defibrillators, 4 single-chamber defibrillators/pacemakers, and 4 biventricular devices). Mean age was 71.2 ± 6.0 years with mean duration of indwelling CIED was 1821.1 ± 1586.8 days (see Table). Two (0.07%) patients had lead-related fibrin on ICE imaging. There was no significant difference in lead(s) threshold, impedance, or sensing post-procedure or at 30-days follow-up compared to pre-procedure (see Table). There were no intra- or post-op thromboembolic events or subsequent device infection over 30 days of follow-up. None of the patients required lead revision. One patient underwent CIED extraction after 11 months for an unrelated secondary device infection. Conclusion: Radiofrequency catheter ablation for AF can be safely performed without fluoroscopy in patients with CIED.

Intracardiac echocardiography from coronary sinus.

Intracardiac echocardiography (ICE) has become an essential tool and is an integral part of percutaneous interventional and electrophysiology (EP) procedures. Intracardiac echocardiography offers real-time, high-quality, near-field evaluation of cardiac anatomy. Standard ICE imaging includes placing the catheter in the right atrium (RA), right ventricle (RV), or left atrium (LA, via the transeptal approach). Coronary sinus echocardiography (CSE) is another alternative, where the ICE catheter is positioned in the coronary sinus (CS). This approach offers better catheter stability and allows operators to visualize cardiac structure with particularly excellent views of the LA, LAA, left ventricle (LV), and mitral annulus. Additionally, CSE is an attractive alternative in cases with unfavorable interatrial septum or fossa ovalis anatomical features that could lead to difficulty advancing ICE catheter in left atrium. In this article focusing on CSE, we provide illustration-based guidance to help operators identify critical cardiac structures from CSE.

Pulsed Field Ablation of the Porcine Ventricle Using a Focal Lattice-Tip Catheter.

Our understanding of catheter-based pulsed field ablation (PFA) of the ventricular myocardium is limited. We conducted a series of exploratory evaluations of ventricular PFA in swine ventricles. A focal lattice-tip catheter was used to deliver proprietary biphasic monopolar PFA applications to swine ventricles under general anesthesia, with guidance from electroanatomical mapping, fluoroscopy, and intracardiac echocardiography. We conducted experiments to assess the impact of (1) delivery repetition (2×, 3×, or 4×) at each location, (2) epicardial PFA delivery, and (3) confluent areas of shallow healed endocardial scar created by prior PFA (4 weeks earlier) on subsequent endocardial PFA. Additional assessments included PFA optimized for the ventricle, lesion visualization by intracardiac echocardiography imaging, and immunohistochemical insights. Experiment no. 1: lesions (n=49) were larger with delivery repetition of either 4× or 3× versus 2×: length 17.6±3.9 or 14.2±2.0 versus 12.7±2.0 mm (P<0.01, P=0.22), width 13.4±1.8 or 10.6±1.3 versus 10.5±1.1 mm (P<0.01, P=1.00), and depth 6.1±2.1 or 5.1±1.3 versus 4.2±1.0 mm (P<0.01, P=0.21). Experiment no. 2: epicardial lesions (n=18) were reliably created and comparable to endocardial lesions: length 24.6±9.7 mm (n=5), width 15.6±4.6 mm, and depth 4.5±3.7 mm. Experiment no. 3: PFA (n=16) was able to penetrate to a depth of 4.8 (interquartile range, 4.5-5.4) mm in healthy myocardium versus 5.6 (interquartile range, 3.6-6.6) mm in adjacent healed endocardial scar (P=0.79), suggesting that superficial scar does not significantly impair PFA. Finally, we demonstrate, PFA optimized for the ventricle yielded adequate lesion dimensions, can result in myocardial activation, can be visualized by intracardiac echocardiography, and have unique immunohistochemical characteristics. This in vivo evaluation offers insights into the behavior of endocardial or epicardial PFA delivered using the lattice-tip catheter to normal or scarred porcine ventricular myocardium, thereby setting the stage for future clinical studies.

PO-626-08 LEFT ATRIAL APPENDAGE OCCLUSION WITH LEFT ATRIAL FOUR DIMENSIONAL INTRACARDIAC ECHOCARDIOGRAPHY

Left atrial appendage occlusion, using intracardiac echocardiography (ICE) continues to evolve. One of the more recent advancements is the Siemens 4-D ACUSON AcuNav Volume ICE® (Siemens, Malvern PA). This catheter allows for 4D images to optimize the provider’s implant visibility and minimize the maneuvers required to assess the LAA. Although right atrial imaging has been more commonly described, left atrial 4-D ICE imaging may allow for better unobstructed imaging. Demonstrate implant technique using 4-D ICE (ACUSON AcuNav Volume ICE®, Siemens, Malvern PA) guided LAAO using optimal left atrial imaging. The 4-D ICE catheter is a 12.5 Fr catheter that is initially guided into the RA to assist in navigating transspetal puncture. The probe obtains a field of view which is 90 degrees by 50 degrees with frame rate of 16 volumes per second. The catheter visualizes the septum/fossa ovalis for transseptal puncture. Following successful puncture, the ICE catheter and LAAO Sheath can be guided through a single puncture with fluoroscopic and 4-D ICE guidance. Using multiplanar reconstruction, 4-D ICE requires a single catheter position to visualize the entirety of the left atrial appendage. We evaluate the mid left atrium with posterior flexion and counterclockwise rotation to visualize the LAA ostium. Multiplanar reconstruction can be manipulated to demonstrate the enface LAA ostium view the maximal length of the appendage. The landing zone dimensions are calculated using the reconstructions (Figure 1). Once the LAA has been appropriately visualized, the Watchman access sheath is advanced to the LA. Cineangiographic images of the LAA are obtained and the Watchman device is sized and delivered. Our single center experience has recorded more than 75 successful LAAO implants using this 4D ICE left atrial imaging technique. The advancement in visibility and ability to get a thorough assessment of the LAA, without complex manipulation of a 2-D ICE or TEE probe is ideal. The evolution of ICE with 4-D technology has allowed for an improved imaging experience during implant, especially when imaging from within the left atrium.

Automated catheter tip repositioning for intra-cardiac echocardiography.

Intra-Cardiac Echocardiography (ICE) is a powerful imaging modality for guiding cardiac electrophysiology and structural heart interventions. ICE provides real-time observation of anatomy and devices, while enabling direct monitoring of potential complications. In single operator settings, the physician needs to switch back-and-forth between the ICE catheter and therapy device, making continuous ICE support impossible. Two operator setups are sometimes implemented, but increase procedural costs and room occupation. ICE catheter robotic control system is developed with automated catheter tip repositioning (i.e., view recovery) method, which can reproduce important views previously navigated to and saved by the user. The performance of the proposed method is demonstrated and evaluated in a combination of heart phantom and animal experiments. Automated ICE view recovery achieved catheter tip position accuracy of [Formula: see text] mm and catheter image orientation accuracy of [Formula: see text] in animal studies, and [Formula: see text]mm and [Formula: see text] in heart phantom studies, respectively. Our proposed method is also successfully used during transseptal puncture in animals without complications, showing the possibility for fluoro-less transseptal puncture with ICE catheter robot. Robotic ICE imaging has the potential to provide precise and reproducible anatomical views, which can reduce overall execution time, labor burden of procedures, and X-ray usage for a range of cardiac procedures.