Intracardiac Echo Research Articles

Remote controlled robot assisted cardiac navigation: feasibility assessment and validation in a porcine model

Despite the recent advances in catheter design and technology, intra-cardiac navigation during electrophysiology procedures remains challenging. Incorporation of imaging along with magnetic or robotic guidance may improve navigation accuracy and procedural safety. In the present study, the in vivo performance of a novel remote controlled Robot Assisted Cardiac Navigation System (RACN) was evaluated in a porcine model. The navigation catheter and target sensor were advanced to the right atrium using fluoroscopic and intra-cardiac echo guidance. The target sensor was positioned at three target locations in the right atrium (RA) and the navigation task was completed by an experienced physician using both manual and RACN guidance. The navigation time, final distance between the catheter tip and target sensor, and variability in final catheter tip position were determined and compared for manual and RACN guided navigation. The experiments were completed in three animals and five measurements recorded for each target location. The mean distance (mm) between catheter tip and target sensor at the end of the navigation task was significantly less using RACN guidance compared with manual navigation (5.02 ± 0.31 vs. 9.66 ± 2.88, p = 0.050 for high RA, 9.19 ± 1.13 vs. 13.0 ± 1.00, p = 0.011 for low RA and 6.77 ± 0.59 vs. 15.66 ± 2.51, p = 0.003 for tricuspid valve annulus). The average time (s) needed to complete the navigation task was significantly longer by RACN guided navigation compared with manual navigation (43.31 ± 18.19 vs. 13.54 ± 1.36, p = 0.047 for high RA, 43.71 ± 11.93 vs. 22.71 ± 3.79, p = 0.043 for low RA and 37.84 ± 3.71 vs. 16.13 ± 4.92, p = 0.003 for tricuspid valve annulus. RACN guided navigation resulted in greater consistency in performance compared with manual navigation as evidenced by lower variability in final distance measurements (0.41 vs. 0.99 mm, p = 0.04). This study demonstrated the safety and feasibility of the RACN system for cardiac navigation. The results demonstrated that RACN performed comparably with manual navigation, with improved precision and consistency for targets located in and near the right atrial chamber.

Noncompacted ventricular myocardium: characterization by intracardiac echo

We report a patient with clinical manifestation of arrhythmias and evidence of noncompacted myocardium in both left and right ventricular apex. The diagnosis was made with intracardiac echo performed during the electrophysiologic study. This method has allowed the diagnosis of noncompaction of the ventricular myocardium due to its high resolution. Color Doppler showed trabecular recesses in communication with the ventricular cavity that could not be identified with transthoracic echocardiography.

Intercommissural Lead Placement into a Right Ventricular Coronary Sinus-Utility of Intracardiac Echo Guidance

Patients with congenital heart disease and prosthetic valves frequently present management dilemmas related to cardiac pacing and lead placement. Permanent pacing of the right ventricle across a bioprosthetic tricuspid valve presents discreet issues related to its potential for traumatic injury and subsequent prosthetic valve dysfunction. Coronary sinus (CS) lead placement is being used more frequently to avoid valvular dysfunction. We report an unusual case in which the CS ostium was located ventricular to the tricuspid prosthesis. Intracardiac echocardiography was used to position a CS lead between the commissures of the tricuspid prosthesis resulting in trivial regurgitation acutely and at 1-year follow-up.

Radiofrequency Hot Balloon Catheter Ablation of Atrial Fibrillation: Results of a Multicenter Clinical Trial in Japan

Background: We evaluate the safety and efficacy of a radiofrequency hot balloon catheter (Toray-Satake Balloon; TSB) for the treatment of the patients with AF. Methods and Results: A total of thirty patients (26 men, 60±9 years) with drug-resistant AF (paroxysmal n=26, persistent n=4) were enrolled in this study. Under general anesthesia (n=12) or deep sedation (n=18), we performed isolation of all PVs including PV antrum, only by use of TSB. The center temperature of the balloon (60–70C) and the delivery time of RF energy (90–240 seconds) were determined by the wall thickness of each PV, measured by intra-cardiac echo. Complete PV isolation was observed in 110 of 121 PVs (91%), and decreased PV potentials were left in 4/31 (13%) at right superior PV, 4/30 (13%) at left superior PV, and 3/30 (10%) at left inferior PV. Total procedure times were (102±27 min). Total fluoroscopic times and total application times were (31±14 min) and (12±2 times), respectively. After a single procedure, twenty-seven of 30 patients (87%) were free from AF without anti-arrhythmic drugs during 6 months follow-up period. There were no complications such as stroke, esophageal fistula, symptomatic PV stenosis, phrenic nerve palsy, pyloric spasm. Conclusion: Ablation by TSB might be time-saving, safety and quite promising therapy for the patients with AF.

Intracardiac echocardiography off piste? Closure of the left atrial appendage using ICE and local anesthesia

Left atrial appendage (LAA) occlusion is increasingly accepted to reduce the risk of stroke in patients with atrial arrhythmia who are unsuitable for routine anticoagulation. It is generally performed under general anesthesia, guided by transoesophageal echocardiography with accurate imaging being essential for correct deployment of the device. We present a case where LAA occlusion was done under local anesthesia in a high-anesthetic risk patient, using novel placement of an intracardiac echo probe via a Mullins sheath in the right ventricular outflow tract and pulmonary artery. This allowed accurate visualization of device deployment in the LAA. This technique may increase the spectrum of patients who may benefit from the procedure and decrease procedure time, fluoroscopy, and procedure-related morbidity.

The Association of Patent Foramen Ovale Morphology and Stroke Size in Patients With Paradoxical Embolism

Patent foramen ovale (PFO) has been implicated in the pathogenesis of cryptogenic stroke through paradoxical embolization to the cerebral circulation. This study evaluated the relationship between the morphological and functional size of the PFO by echocardiography compared with cerebral infarct volume identified on MRI. Patients who were referred to interventional cardiology with the diagnosis of cryptogenic stroke were included and had either a transesophageal echocardiogram or an intracardiac echo and a brain MRI at the time of stroke. Transesophageal echocardiogram or intracardiac echo was used to obtain PFO measurements. MRI of the brain with 3 sequences (T2, diffusion-weighted imaging, and fluid-attenuated inversion recovery) was used to diagnose acute stroke and measure the infarct volume. In the 72 patients studied, the median measured stroke volume was 4.3 cm(3) on diffusion-weighted imaging, 4.1 cm(3) on T2, and 3.5 cm(3) on fluid-attenuated inversion recovery. There was no significant correlation between the PFO height, length, septum secundum thickness, or echo bubble grade and the infarct volume measured from the 3 MRI sequences. There was a significant correlation between septal excursion distance and infarct volume (r=0.35; P=0.005), but the 12 patients with atrial septal aneurysm did not have the largest strokes. This analysis revealed that septal excursion distance correlates with stroke size by MRI. However, smaller PFO size without the presence of atrial septal aneurysm may still be associated with significant strokes. There was no significant association between PFO height, length by echo, or shunt grade by transcranial Doppler study and brain infarct volume. Therefore, PFO size or morphology should not be the only criteria to decide whether a PFO should be closed.

138 Catheter ablation of atrial fibrillation whilst taking therapeutic warfarin: a british experience: Abstract 138 Table 1

Introduction Peri-procedural anticoagulation of patients undergoing catheter ablation of atrial fibrillation (AF) reduces thromboembolism risk but with potential haemorrhagic complications. In the UK, warfarin is generally discontinued pre-procedure and low molecular weight heparin (LMWH) used to bridge the sub-therapeutic period. In some institutions around the world ablation is performed with a therapeutic International Normalised Ratio (INR) and problems with LMWH administration are reduced, but the trans-septal puncture is usually performed under intracardiac echo (ICE) guidance. In the UK, cost prevents routine ICE use but we aimed to see if this could still be done safely within our system. Methods Fifty-six consecutive AF ablation patients were studied prospectively (warfarin group). A target INR of 2–3 was used for the procedure. A double trans-septal puncture technique was used. Unfractionated heparin was still used to maintain ACT between 300 and 350. Wide area circumferential ablation was performed along with any other ablation clinically indicated. If the INR was less than two at the time of ablation, LMWH was used afterwards until it was two or more. A group of 56 patients prior (bridging LMWH group) were compared. Endpoints were minor bleeding (haematomas), major bleeding (transfusion requiring), pericardial effusions, and stroke. Results In two patients the INR was >3 so the procedure was delayed. In 11 the INR was Conclusions AF ablation can be performed safely with therapeutic warfarin in the UK, with a low rate of procedure cancellation. Although the number of patients studied was relatively small, there was a lower incidence of minor bleeding with this approach than with bridging LMWH and a low rate of other complications in both groups. This strategy also reduces the need for LMWH after ablation which has both cost and patient comfort implications.

Diagnosis and therapy for pulmonary arteriovenous fistula in patients with presumed patent foramen ovale

An increasing number of patients are being referred for PFO closure for prevention of recurrent paradoxical embolism. Diagnosis is usually made using hand agitated echo bubble contrast with transthoracic or transesophageal echo. It is inevitable that some of these patients will have pulmonary arteriovenous fistulae (PAVF), either with or without associated PFO, which may be the sole cause of paradoxical embolism, or remain after PFO closure as a source of continued embolization. Intravenous contrast echo for the diagnosis of PFO is both insensitive and nonspecific. We describe a method to diagnose and localize PAVF during a catheterization procedure using intracardiac echo in conjunction with selective injection of bubble contrast into the pulmonary arteries. This allows for the rapid and accurate diagnosis of PAVF when a PFO is not found and for the exclusion of associated PAVF when PFO exists.

Esophageal Fistula Formation Despite Esophageal Monitoring and Low-Power Radiofrequency Catheter Ablation for Atrial Fibrillation

Esophageal fistula is a rare but devastating complication that may occur after catheter ablation of atrial fibrillation.1 The mechanism of esophageal injury is not known. Potential mechanisms for injury include direct thermal injury and ischemic injury from damage to the esophageal blood supply. Current ablation strategies use various methods to avoid esophageal injury. We describe an unusual manifestation of esophageal injury despite multiple preventive measures. A 45-year-old man with a medical history of hypertension, mild aortic stenosis, body mass index of 26.78 kg/m2 (weight, 192 pounds; height, 5 feet, 11 inches), and symptomatic recurrent persistent atrial fibrillation refractory to amiodarone for 4 years underwent a radiofrequency catheter ablation procedure under general anesthesia using sevoflurane, fentanyl, midazolam and rocuronium. A preprocedure computed tomography (CT) scan was used to create 3D reconstruction of the left atrium and pulmonary veins. Intracardiac echo (Carto Sound, Biosense Webster, Diamond Bar, Calif) was used to create left atrial and pulmonary vein geometry, and this was merged with the CT image (Figure 1). An orogastric tube was placed in the esophagus at the level of left atrium, and barium was injected to obtain fluoroscopic images of …

Right Atrial Thrombus Aspiration Guided by Intracardiac Echocardiography During Catheter Ablation for Atrial Fibrillation

A 56-year-old man with psoriasis and a 2-year history of paroxysmal atrial fibrillation and flutter was admitted for catheter ablation. The procedure was performed under general anesthesia. The patient arrived to the electrophysiology laboratory in atrial flutter. A preprocedural transesophageal echocardiogram confirmed the absence of intraatrial thrombus. The patient was chronically anticoagulated with warfarin, and the international normalized ratio (INR) on the day of the procedure was 2.4. After vascular access was obtained, a duodecapolar catheter was placed from the left femoral vein with the 10 distal electrodes in the coronary sinus and 10 proximal electrodes in the right atrium (RA). A phased-array intracardiac echo (ICE) catheter was placed via the left femoral vein into the RA. Intravenous heparin, 5000 U, was given after initial catheter placement. The presence of typical clockwise atrial flutter was confirmed by activation and entrainment mapping. A cavo-tricuspid isthmus ablation line …

Multidetector computed tomography with delay imaging for detection of left atrial thrombus

1934 5925/$ see front matter 2009 doi:10.1016/j.jcct.2009.05.018 A 51-year-old woman with nonobstructive hypertrophic cardiomyopathy and symptomatic atrial fibrillation underwent preoperative dual-source gated cardiac CT (DSCT) (Somatom Definition; Siemens Medical Solutions Forchheim, Germany). A filling defect was identified in the left atrial appendage (LAA) by DSCT which persisted on repeat images at a 1-minute delay. (Fig. 1A and B and Supplementary Movies 1 and 2). Transesophageal echocardiography performed later that day (Fig. 1C) showed moderate spontaneous echo contrast (SEC) but no thrombus. Left atrial ablation was done with the use of intracardiac echo before transseptal puncture, which confirmed the absence of an LAA thrombus. The strength of DSCT for evaluation of the LAA is its high negative predictive value (ie, a normal contrast-filled LAA excludes LAA thrombus with high probability).

An Ultrasound-based Localization Algorithm for Catheter Ablation Guidance in the Left Atrium

We present a method for catheter localization in the left atrium based on the unscented particle filter (UPF), a Monte Carlo method employed in stochastic state estimation. Using an intracardiac echo (ICE) ultrasound catheter, we acquire ultrasound images of the atrium from multiple configurations and iteratively determine the catheter’s pose with respect to anatomy. At each time step, the catheter’s change in pose is determined using either a six-degree-of-freedom electromagnetic pose sensor or a robotic guide catheter whose kinematics serve as a pseudo-pose measurement. Sensor and kinematic model uncertainties are explicitly considered when computing the localization estimate. Acquired ultrasound images are compared with simulated ultrasound images based on segmented computed tomography (CT) or magnetic resonance (MR) data of the left atrium. The results of these comparisons are used to refine the localization estimate. After considering less than 30 seconds’ worth of ICE data, our algorithm converges to an accurate pose estimate. Furthermore, our algorithm is robust to sensor drift and kinematic model errors, as well as gradual, unmodeled movements in the anatomy. Such problems typically complicate traditional image-based localization.

A probabilistic framework for freehand 3D ultrasound reconstruction applied to catheter ablation guidance in the left atrium

The catheter ablation procedure is a minimally invasive surgery used to treat atrial fibrillation. Difficulty visualizing the catheter inside the left atrium anatomy has led to lengthy procedure times and limited success rates. In this paper, we present a set of algorithms for reconstructing 3D ultrasound data of the left atrium in real-time, with an emphasis on automatic tissue classification for improved clarity surrounding regions of interest. Using an intracardiac echo (ICE) ultrasound catheter, we collect 2D-ICE images of a left atrium phantom from multiple configurations and iteratively compound the acquired data into a 3D-ICE volume. We introduce two new methods for compounding overlapping US data-occupancy-likelihood and response-grid compounding-which automatically classify voxels as "occupied" or "clear," and mitigate reconstruction artifacts caused by signal dropout. Finally, we use the results of an ICE-to-CT registration algorithm to devise a response-likelihood weighting scheme, which assigns weights to US signals based on the likelihood that they correspond to tissue-reflections. Our algorithms successfully reconstruct a 3D-ICE volume of the left atrium with voxels classified as "occupied" or "clear," even within difficult-to-image regions like the pulmonary vein openings. We are robust to dropout artifact that plagues a subset of the 2D-ICE images, and our weighting scheme assists in filtering out spurious data attributed to ghost-signals from multi-path reflections. By automatically classifying tissue, our algorithm precludes the need for thresholding, a process that is difficult to automate without subjective input. Our hope is to use this result towards developing 3D ultrasound segmentation algorithms in the future.

Real-time imaging in electrophysiology: from intra-cardiac echo to real-time magnetic resonance imaging

Interventional electrophysiology using catheter ablation is a rapidly growing field that has allowed for the cure of arrhythmias originating from every cardiac chamber as well as the great vessels. The keys to the success of the ablation procedure are targeting critical areas required to initiate and sustain the arrhythmias as well as insuring the delivery of effective ablation lesions. Understanding the intricate relationship between the anatomical structures and their functional relationship to the arrhythmia, or the ‘electro-anatomical substrate’, represents the greatest limitation to the success of the ablation procedure. For atrial fibrillation, the electro-anatomical substrate largely consists of the posterior wall of the left atrium which includes the pulmonary vein antra,1 and most operators aim for at least electrical isolation of the pulmonary veins and consider this to be an acceptable endpoint for the procedure.2,3 Several technological tools are currently available to guide catheter navigation with more advances coming down the pipeline. When used in combination, these have made ablation procedures safer, shorter, and more successful.4 These include X-ray fluoroscopy, electro-anatomical mapping systems with … *Corresponding author. Tel: +1 801 581 2572, Fax: +1 435 658 1527. Email: nassir.marrouche{at}hsc.utah.edu

Transapical endovascular implantation of neochordae using a suction and suture device☆

Neochordae implantation is a standard method for treatment of mitral valve prolapse. We describe a transcatheter technology enabling transapical endovascular chordal implantation. Six adult pigs were anesthetized. Two 10F sheaths were introduced in the femoral vessels for monitoring and intracardiac echo. After midline sternotomy, the pericardium was opened, the apex was punctured inside two 2-0 polypropylene purse strings. A 0.035 in J tipped guidewire was introduced in the left ventricle and an ultra stiff 14F sheath (guide catheter) inserted through the apex. A suction-and-suture device was introduced in the left ventricle. The mitral valve was crossed under echo guidance. Using suction, either the anterior (two cases) or posterior (four cases) leaflet was captured and a loop of 4-0 polypropylene was thrown at the edge of the leaflet. The loop, with a pledget, was exteriorized through the introducer. The introducer was removed and the purse-string tied. Under echo guidance, the neochordae suture was pulled and tied over a pledget to evoke leaflet tethering. The animals were sacrificed and gross anatomy reviewed. Leaflet capture was feasible in the intended location in all cases. Following suture tethering, variable degrees of MR were obtained. At gross anatomy, the neochordae were positioned at 1-4mm from the leaflet free edge, and were firmly attached to the leaflets. Transcatheter endovascular neochordae implantation is feasible. A prolapse model is needed to further demonstrate feasibility under pathologic conditions. The apical approach allows easy and direct route to transcatheter beating heart minimally invasive mitral repair.

Impact of a comprehensive safety program on radiation exposure during catheter ablation of atrial fibrillation: a prospective study

Pulmonary vein antral isolation (PVAI) is an effective treatment for atrial fibrillation and involves prolonged procedure and fluoroscopy times. This study assesses the impact of a comprehensive radiation safety program on patient and operator radiation exposure during PVAI. We evaluated a comprehensive radiation safety program including: (1) verbal reinforcement of previous fluoroscopy times (2) effective collimation (3) minimizing source-intensifier distance and (4) effective lead shield use. Exposure doses in 41 consecutive patients without (group-I, n = 21) and with (group-II, n = 20) the use of radiation safety program were assessed. PVAI was done using intracardiac echo (ICE) guided roving circular mapping catheter. A 3-dimensional mapping system was used in 27% cases for additional guidance. Operator and patient exposure was measured during the PVAI. The age, gender, body mass index and AF duration were similar in both of the groups. The total procedure (166 +/- 56 vs 178 +/- 38 min, p = 0.54) and fluoroscopy times (74 +/- 24 vs 70 +/- 20 min, p = 0.72) were comparable. Group-II had significantly lower dose area product (234 +/- 120 vs 548 +/- 363 Gy cm(2), p = 0.03) compared to group-I. The mean operator exposure was reduced by half and mean patient peak skin dose by three to ten times with comprehensive radiation safety program. None of the patients were noted to have radiation related skin injuries. Additional lifetime cancer risk was significantly lower in group-II patients (0.08 vs 0.2%, p < 0.001) than group-I. Implementation of a comprehensive radiation safety program described above significantly decreases the radiation exposure to the patient as well as the operator.

Abstract 4089: Unique Epicardial Substrate in Non-Ischemic CM: Echo Signature, Electrogram Correlates and Outcome with Substrate Based Ablation

We present a unique series of patients (pts) with non-ischemic cardiomyopathy (NICM) and unmappable ventricular tachycardia (VT) who demonstrated predominantly normal left ventricular (LV) endocardial (ENDO) voltage and abnormal epicardial (EPI) substrate defined by intracardiac echo (ICE) and fractionated electrograms (EGMS). This substrate served as an appropriate ablation target for VT. All patients underwent ICE imaging and detailed ENDO and EPI voltage mapping to further characterize the substrate and define the EGM correlates. 5 pts with NICM had increased echogenicity in the lateral epicardium by ICE imaging. Detailed LV ENDO mapping (199 ± 94.5 points) identified no voltage abnormalities in 4 pts. In one pt, a 16.2cm2 low voltage area in the LV ENDO was present and adjacent to the EPI abnormality. In all pts, detailed EPI mapping (477 ± 158 points) revealed a distinct area (20.6 ± 3.6 cm2) of low voltage (&lt;1.0mV) that correlated with the echogenic area. These areas displayed low amplitude EGMS that were wide (&gt;80msec), split, and late (beyond QRS). (Figure 1 ). After excluding coronary branch vessels and the course of the phrenic nerve, all pts underwent substrate based ablation based on pace-mapping and targeting of abnormal EGMS to eliminate the targeted VT. No VT has recurred during mean follow-up of 20mo (range 1–30 mo). Unique EPI substrate in NICM, defined by echo imaging and confirmed by EGM correlates, can be successfully targeted for RF ablation to provide effective VT control.

Use of the Monoplane Intracardiac Imaging Probe in High‐Risk Infants during Congenital Heart Surgery

Imaging options are limited in high-risk infants with small or abnormal oropharyngeal anatomy during congenital heart surgery. All cases in which the monoplane intracardiac echo probe was used for transesophageal intraoperative imaging over a 15-month period at a single institution were reviewed. Eleven patients underwent intraoperative imaging using the intracardiac probe. Patient weight ranged from 1.96 kg to 4 kg. Adequate images of the anatomy relevant to the surgical repair were obtained in all cases. No adverse events related to probe use occurred. Transesophageal echocardiography using the monoplane intracardiac echo probe provides safe and effective imaging in patients who are not candidates for standard transesophageal echocardiography.

Intracardiac ECHO Integration With Three Dimensional Mapping: Role in AF Ablation

Intracardiac ECHO Integration With Three Dimensional Mapping: Role in AF Ablation

Intracardiac ECHO Integration with Three Dimensional Mapping: Role in AF Ablation.

Background: Catheter ablation of atrial fibrillation (AF) is typically guided by 3D mapping. This involves point-by-point reconstruction of the 3D virtual anatomy and may be time consuming and require substantial fluoroscopy exposure. Intracardiac echocardiography (ICE) affords real time imaging of the cardiac structures during mapping and ablation. Methods: Between February and May 2007, 15 patients (100% men, 10 with paroxysmal AF) presenting for AF ablation were offered mapping using a novel system integrating 3D mapping and ICE. A modified ICE probe with a location sensor tracked by the mapping system was positioned in the right atrium (RA). This allowed acquisition of ECG gated images of the left atrium (LA). Endocardial contours were traced on each image and were used to generate a registered 3D map. Results: 3D maps took a mean of 51+/-25 minutes to create, PRIOR to entering the LA and without fluoroscopy. Pulmonary veins and the esophagus were rendered in 3D. A complete map was built from a mean of 46+/-19 contours. Upon instrumentation of the left atrium, the maps were easily distorted if points collected by the mapping catheter were combined with the original map, due to deformation of the left atrial geometry by the relatively stiff ablation catheter. Pulmonary vein antrum isolation was guided by a circular mapping catheter. Since this catheter could not be visualized on the CARTO map, fluoroscopy was used to track its position and the contact between the ablation catheter and the circular mapping catheter. No substantial reduction in fluoroscopy time was thus realized, as expected. At 10+/-1 months of followup, 73% of the patients were in sinus rhythm after the initial three month blanking period. No patient suffered any complications related to the procedure or in follow-up. Conclusions: A mapping system combining ICE and 3D electroanatomical mapping can feasibly reconstruct a 3D shell of the LA and the pulmonary veins without the need to enter the left heart. The map created is sensitive to distortion during point-by-point mapping with the standard ablation catheter.