Phased-array Intracardiac Echocardiography Research Articles

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.

Use of a novel 4D intracardiac echocardiography catheter to guide interventional electrophysiology procedures

Standard two-dimensional (2D), phased-array intracardiac echocardiography (ICE) is routinely used to guide interventional electrophysiology (EP) procedures. A novel four-dimensional (4D) ICE catheter (VeriSight Pro, Philips) can obtain 2D and three-dimensional (3D) volumetric images and cine-videos in real-time (4D). The purpose of this study was to determine the early feasibility and safety of this 4D ICE catheter during EP procedures. The 4D ICE catheter was placed from the femoral vein in ten patients into various cardiac chambers to guide EP procedures requiring transseptal catheterization, including ablation for atrial fibrillation and left atrial appendage closure. 2D- and 3D-ICE images were acquired in real-time by the electrophysiologist. A dedicated imaging expert performed digital steering to optimize and postprocess 4D images. Eight patients underwent pulmonary vein isolation (cryoballoon in seven patients, pulsed field ablation in one, additional radiofrequency left atrial ablation in one). Two patients underwent left atrial appendage closure. High quality images of cardiac structures, transseptal catheterization equipment, guide sheaths, ablation tools, and closure devices were acquired with the ICE catheter tip positioned in the right atrium, left atrium, pulmonary vein, coronary sinus, right ventricle, and pulmonary artery. There were no complications. This is the first experience of a novel deflectable 4D ICE catheter used to guide EP procedures. 4D ICE imaging is safe and allows for acquisition of high-quality 2D and 3D images in real-time. Further use of 4D ICE will be needed to determine its added value for each EP procedure type.

Intravascular Ultrasound-Guided Transvenous Biopsy of Abdominal and Pelvic Targets Difficult to Access by Percutaneous Needle Biopsy: Technique and Initial Clinical Experience

PurposeTo report initial clinical experience with intravascular ultrasound (US)-guided transvenous biopsy (TVB) for perivascular target lesions in the abdomen and pelvis using side-viewing phased-array intracardiac echocardiography catheters. Materials and MethodsIn this single-institution, retrospective study, 48 patients underwent 50 intravascular US-guided TVB procedures for targets close to the inferior vena cava or iliac veins deemed difficult to access by conventional percutaneous needle biopsy (PNB). In all procedures, side-viewing phased-array intracardiac echocardiography intravascular US catheters and transjugular liver biopsy sets were inserted through separate jugular or femoral vein access sheaths, and 18-gauge core needle biopsy specimens were obtained under real-time intravascular US guidance. Diagnostic yield, diagnostic accuracy, and complications were analyzed. ResultsIntravascular US-guided TVB was diagnostic of malignancy in 40 of 50 procedures for a diagnostic yield of 80%. There were 5 procedures in which biopsy was correctly negative for malignancy, with a per-procedure diagnostic accuracy of 90% (45/50). Among the 5 false negatives, 2 patients underwent repeat intravascular US-guided TVB, which was diagnostic of malignancy for a per-patient diagnostic accuracy of 94% (45/48). There were 1 (2%) mild, 2 (4%) moderate, and 1 (2%) severe adverse events, with 1 moderate severity adverse event (venous thrombosis) directly attributable to the intravascular US-guided TVB technique. ConclusionsIntravascular US-guided TVB performed on difficult-to-approach perivascular targets in the abdomen and pelvis resulted in a high diagnostic accuracy, similar to accepted thresholds for PNB. Complication rates may be slightly higher but should be weighed relative to the risks of difficult PNB, surgical biopsy, or clinical management without biopsy.

Utility of intracardiac echocardiography during transvenous lead extraction

Transvenous lead extraction (TLE) carries a significant risk of intraprocedural complications. Phased-array intracardiac echocardiography (ICE) is widely used during cardiac procedures; however, its utility during TLE has not been well described. We sought to define the utility of ICE imaging during TLE. Fifty patients referred for TLE were included. Patients underwent ICE imaging before and throughout TLE. Clinical characteristics of the patients, ICE findings, and procedural outcomes were collected and analyzed. Of the 50 patients, 18 (36%) were found to have visible binding sites in the ICE field of view; 13 (26%) had intracardiac binding sites only, and 5 (10%) had both superior vena cava (SVC) and intracardiac binding sites. Lead-adherent echodensities (LAEs) were found in 36 patients (72%), of whom 7 (14%) had bacteremia. Patients with SVC and/or intracardiac binding sites were more likely to have a complex extraction, defined as that requiring the use of internal jugular or femoral venous access, advancement of extraction apparatus beyond the SVC, disruption of lead structure during the procedure, or resulting in major complications (56% vs 0%; P ≤ .0001). ICE imaging during TLE can be used to assess the presence of lead binding sites, LAEs, and procedural complications. LAEs were found in the majority of patients, mostly in the absence of bacteremia. The presence of ICE-detected lead binding sites is predictive of a more complex extraction procedure.

Intracardiac Echo Guidance of Intervention

Interventional therapy for congenital and structural heart diseases has become more and more popular nowadays. Transesophageal echocardiography (TEE) has been successfully used for guiding the procedure but requires general anesthesia. Intracardiac echocardiography (ICE) uses a miniaturized ultrasound tipped catheter which is placed in the heart to obtain the image. Imaging with ICE has evolved from cross-sectional imaging using a rotating transducer (similar to intravascular ultrasound) to sector-based imaging using a phased-array transducer. Phased-array ICE has many advantages over rotational ICE including a greater frequency range, greater depth of field, steerability, and the possibility of acquiring Doppler and color flow imaging. With their steerability, phased-array catheters can be easily advanced and positioned through short sheaths rather than through long guide sheaths. The AcuNav (Siemens Medical) phased-array ICE was first introduced in Taiwan in December 2004. In our experience, ICE can provide excellent images for device closure of ASD, VSD, ruptured sinus Valsalva aneurysm and transseptal puncture eliminating the need of general anesthesia.

Visualization of the left atrial appendage by phased-array intracardiac echocardiography from the pulmonary artery in patients with atrial fibrillation

The left atrial appendage (LAA) represents the major source of cardiac thrombus formation in patients with atrial fibrillation (AF). Phased-array intracardiac echocardiography (ICE) has become available and frequently used during catheter ablation of AF. We attempted to study the feasibility of using ICE for the visualization and evaluation of the LAA from the pulmonary artery (PA) in patients with AF. Eighty patients with AF undergoing catheter ablation (70 males, 57.5 ± 9.1 years) were included. Transoesophageal echocardiography was performed on the prior day before the catheter ablation, and ICE was performed just before the transseptal puncture during the catheter ablation. The ICE catheter was advanced up into the PA from the femoral vein, where the LAA was clearly and entirely visualized by manipulating the ICE catheter. We compared the degree of spontaneous echo contrast, and the correlation was obtained between the ICE and TEE (κ = 0.534, P < 0.001). Furthermore, the LAA flow velocity (LAA emptying and filling velocities) measured by ICE had a good correlation to that measured by TEE (R = 0.872, P < 0.01 and R = 0.753, P < 0.01, respectively). No patients developed any complications. The utilization of ICE in the PA is feasible for the observation and evaluation of the LAA.

Safety of radiofrequency catheter ablation without coronary angiography in aortic cusp ventricular arrhythmias.

Ventricular arrhythmias (VAs) originating from the aortic root are common. Coronary angiography is typically recommended before catheter ablation to document proximity of the ablation catheter to the coronary ostia. To investigate how often catheter ablation in the aortic root could be guided by phased-array intracardiac echocardiography (ICE) and electroanatomic mapping without requiring aortography or coronary angiography. We reviewed consecutive patients referred for aortic root VAs to operators experienced in the use of ICE at a single center. An ICE catheter and a 3.5-mm irrigated ablation catheter were used in all cases, and the need for angiography before ablation was documented. Acute success and acute and 30-day complications were noted. Thirty-five patients (age 58 ± 13 years; 74% men) were referred for the ablation of VAs; 32 of 35 (91%) underwent ablation using ICE and 3-dimensional mapping without the need for coronary angiography. Successful acute ablation was achieved in 29 of 35 (83%) patients. In all cases, the catheter tip was directly visualized with ICE >1 cm from the coronary ostia. The site of origin of the earliest VA was the left cusp (17 of 35 [49%]), right cusp (9 of 35 [26%]), right-left cusp junction (8 of 35 [23%]), or right-noncoronary cusp junction (1 of 35 [3%]). There were no cases of coronary injury, embolic stroke, aortic root perforation, worsening of aortic regurgitation, or death acutely or at 30 days. Radiofrequency ablation of VAs originating from the aortic root may be safely performed using ICE and electroanatomic mapping in the majority of cases without the need for coronary angiography.

Intra-cardiac echocardiography guided catheter ablation of a right posterior accessory pathway in a patient with Ebstein׳s anomaly

We report a case of Ebstein׳s anomaly in which radiofrequency catheter ablation of an accessory pathway was successfully performed under intra-cardiac echocardiography. A 50-year-old woman was referred to our hospital for radiofrequency catheter ablation of a paroxysmal supraventricular tachycardia. A 12-lead surface electrocardiogram revealed ventricular pre-excitation associated with type B Wolff–Parkinson–White syndrome. In the baseline electrophysiological study, an orthodromic atrioventricular reciprocating tachycardia with a right posterior accessory pathway was induced. A phased-array intra-cardiac echo probe was positioned in the right atrium to visualize the atrioventricular junction. The key structures for catheter ablation, such as the atrialized right ventricle, atrioventricular junction, and tricuspid valve, were clearly visualized on intra-cardiac echocardiography. Radiofrequency current was successfully delivered at the atrioventricular junction, where a Kent potential was recorded. During a 6-month follow-up period, the patient was free from arrhythmias. The findings in this case suggest that phased-array intra-cardiac echocardiography is useful for ablation of right-sided accessory pathways in patients with Ebstein׳s anomaly.

Analysis of the left atrial appendage morphology by intracardiac echocardiography in patients with atrial fibrillation

Detailed information regarding the structure and dimensions of the left atrial appendage (LAA) is required to guide implantation of LAA occlusion devices in patients with atrial fibrillation (AF). Currently, this procedure is guided by transesophageal echocardiography (TEE). The objective of this study was to evaluate the accuracy of intracardiac echocardiography (ICE) in assessing LAA dimensions. The LAA anatomy was analyzed in 21 consecutive patients (age 62 ± 9years, five women, six paroxysmal AF) who underwent catheter ablation for AF. All patients had pre-procedural scans (computed tomography (CT), N = 9; magnetic resonance imaging (MRI), N = 12) of the left atrium (LA). An 8-Fr phased-array ICE catheter was used to obtain images of the LAA. The LAA was visualized with the ICE probe placed sequentially in the right atrium (RA, N = 21 patients), in the coronary sinus (CS, N = 20 patients), and in the LA (N = 21 patients). ICE imaging from the LA showed a LAA ostium diameter of 24 ± 4mm and a LAA depth of 32 ± 4mm. There was strong correlation between the measurements by ICE and the values obtained by CT and MRI. The LAA was visualized in all cases from all locations (RA, CS, and LA), but complete visualization of the LAA could not be obtained from the RA and the CS in a significant number of cases, preventing accurate measurements. Imaging of LAA using an ICE probe positioned in the LA results in accurate measurements of LAA dimensions. This imaging modality could potentially be used during implantation of LAA occlusion devices as an alternative to TEE.

Intracardiac echocardiography identifies the substrate of left ventricular papillary muscle ectopy

A patient without organic heart disease underwent an electrophysiology study guided by phased-array intracardiac echocardiography (ICE) for frequent, premature ventricular contractions (PVCs) with right bundle branch block and right …

Linear Radiofrequency Microcatheter Ablation Guided by Phased Array Intracardiac Echocardiography Combined with Temperature Decay

Fluoroscopy-guided catheter placement is limited in its ability to determine electrode-endocardial contact and involves radiation exposure. We hypothesized that (1) intracardiac echocardiography (ICE) would provide superior assessment of linear electrode contact compared to fluoroscopy and (2) slow temperature decay upon discontinuation of the radiofrequency current (time for temperature to fall 90% after a 10-second test application of the radiofrequency current T90) would indicate optimal electrode-myocardial contact. Sixty endocardial lesions were created in the atria and ventricles of six goats by simultaneous delivery of the radiofrequency current through two linear electrodes of a microcatheter with a central interelectrode thermocouple. Catheter placement was guided by fluoroscopy. A 7.5-MHz ICE transducer in the right atrium or ventricle assessed electrode contact. T90 and previously reported parameters of electrode contact and lesion formation were recorded. Histomorphometry was performed on the lesions. T90 was 4.27 +/- 4.98 seconds. Lesion depth significantly correlated with ICE assessment of electrode contact (r = 0.56, P = 0.001); T90 upon radiofrequency current offset (r = 0.48, P = 0.008), impedance fall upon radiofrequency current onset (r = 0.37, P = 0.008), bipolar pacing threshold preablation (r =-0.56, P = 0.001), bipolar electrogram amplitude preablation (r = 0.43, P = 0.02), but not with fluoroscopic assessment of the electrode contact (r = 0.18, n.s.). For the prediction of achieving a lesion depth of >2 mm, a T90 of >4.0 seconds yielded a specificity of 86% and a sensitivity of 52%, ICE yielded a specificity and sensitivity of 58% and 68%, respectively, while the specificity and sensitivity of fluoroscopy were 26% and 68%, respectively. Both ICE and T90 provide additional clinical relevance during guidance of cardiac microcatheter ablation.

Forward-looking intracardiac ultrasound imaging using a 1-D CMUT array integrated with custom front-end electronics

Minimally invasive catheter-based electrophysiological (EP) interventions are becoming a standard procedure in diagnosis and treatment of cardiac arrhythmias. As a result of technological advances that enable small feature sizes and a high level of integration, nonfluoroscopic intracardiac echocardiography (ICE) imaging catheters are attracting increasing attention. ICE catheters improve EP procedural guidance while reducing the undesirable use of fluoroscopy, which is currently the common catheter guidance method. Phased-array ICE catheters have been in use for several years now, although only for side-looking imaging. We are developing a forward-looking ICE catheter for improved visualization. In this effort, we fabricate a 24-element, fine-pitch 1-D array of capacitive micromachined ultrasonic transducers (CMUT), with a total footprint of 1.73 mm x 1.27 mm. We also design a custom integrated circuit (IC) composed of 24 identical blocks of transmit/ receive circuitry, measuring 2.1 mm x 2.1 mm. The transmit circuitry is capable of delivering 25-V unipolar pulses, and the receive circuitry includes a transimpedance preamplifier followed by an output buffer. The CMUT array and the custom IC are designed to be mounted at the tip of a 10-Fr catheter for high-frame-rate forward-looking intracardiac imaging. Through-wafer vias incorporated in the CMUT array provide access to individual array elements from the back side of the array. We successfully flip-chip bond a CMUT array to the custom IC with 100% yield. We coat the device with a layer of polydimethylsiloxane (PDMS) to electrically isolate the device for imaging in water and tissue. The pulse-echo in water from a total plane reflector has a center frequency of 9.2 MHz with a 96% fractional bandwidth. Finally, we demonstrate the imaging capability of the integrated device on commercial phantoms and on a beating ex vivo rabbit heart (Langendorff model) using a commercial ultrasound imaging system.

Image integration using intracardiac ultrasound to guide catheter ablation of atrial fibrillation

Three-dimensional (3D) reconstruction of the left atrium (LA) can be performed using real-time intracardiac echocardiography (ICE) to facilitate image integration during atrial fibrillation (AF) ablation. Current users of this technology generally image the LA indirectly from the right atrium (RA). The purpose of this study was to assess the feasibility and accuracy of image integration with placement of the ICE catheter directly in the LA to visualize the LA. Thirty consecutive patients undergoing an AF ablation with the CARTO-Sound system were enrolled. A 10-Fr phased-array ICE catheter was used to obtain two-dimensional echocardiographic images of the LA; in 15 patients the ICE probe was placed in the LA, and in 15 patients it was placed only in the RA. Sequential images were obtained and merged with a preacquired computed tomography/magnetic resonance image. The accuracy of image integration was assessed by the value of the average image integration error after surface registration. Thirty patients (60% paroxysmal AF, LA size = 42 +/- 7 mm, ejection fraction = 62% +/- 10%) were studied. There was no difference in the time required to create the LA anatomic map and perform image integration with imaging from the LA versus the RA (22 +/- 22 vs. 24 +/- 16 minutes; P = .8). The number of ultrasound contours obtained was also similar (LA = 26 +/- 17 vs. RA = 24 +/- 16; P = .7). The average integration error was less with direct LA imaging (LA = 1.83 +/- 0.32 vs. RA = 2.52 +/- 0.58 mm; P = .0004). Direct LA imaging with ICE is feasible and results in improved LA visualization and image integration.

Blinded correlation study of three-dimensional electro-anatomical image integration and phased array intra-cardiac echocardiography for left atrial mapping

The purpose of this study was to compare, in a prospective and operator-blinded fashion, the mapping accuracy of the three-dimensional (3D) electro-anatomical image integration and phased array intracardiac echocardiography (ICE) as a real-time imaging modality. Prospectively, 18 patients undergoing pulmonary vein antrum isolation (PVAI) were included. Patients underwent a cardiac computerized tomography scan to define PV and left atrial (LA) anatomy. Image segmentation and integration was performed by CARTOMERGE, followed by 3D volume rendering and image integration. Error profiles between ICE-guided to CARTO and CARTO-guided to ICE were performed in an operator-blinded fashion over PV predetermined points. All patients underwent successful PVAI. The mean age was 55 +/- 10 years, with a mean LA size of 4.5 +/- 0.3 cm. CARTOMERGE-guided catheter positioning was subject to spatial errors on the order of 0.5-1.0 cm relative to ICE imaging, with greatest magnitude near the LA appendage (LAA) and least near the RIPV. The magnitude of spatial error between these two methods is demonstrable regardless of the choice of reference. During electro-anatomical mapping of the LA, CARTO-guided navigation is associated with considerable spatial error relative to anatomic features as identified by ICE. Adjunctive real-time imaging is needed to ensure accurate delivery of radiofrequency lesions.

Accuracy of Intracardiac Echocardiography for Assessing the Esophageal Course Along the Posterior Left Atrium: A Comparison to Magnetic Resonance Imaging

Atrioesophageal fistula is a potentially fatal complication of ablation in the left atrium (LA) to treat atrial fibrillation. The objective of our study was to systematically evaluate the diagnostic potential of intracardiac echocardiography (ICE) for accurately assessing the esophageal course along the posterior LA. Thirty-five patients underwent magnetic resonance imaging (MRI) before and ICE during pulmonary vein (PV) isolation to visualize the esophagus. The location of the esophagus was determined in relation to the PVs and anatomic regions of the LA by both ICE and MRI. Using the MRI images as a reference, the accuracy of ICE localization was assessed. The most common location for the esophagus to appear was the mid-posterior wall (80% of patients by ICE, 71% of patients by MRI), followed by the left posterior wall (71% of patients by ICE, 63% of patients by MRI) and the right posterior wall (60% of patients by ICE, 51% of patients by MRI). The esophagus was seen to course near the left PV antrums (left superior PV antrum 34% of patients by ICE and MRI; left inferior PV antrum 34% of patients by ICE, 37% of patients by MRI), left superior PV (17% of patients by ICE, 20% of patients by MRI), left inferior PV (17% of patients by ICE and MRI), right inferior PV antrum (29% of patients by ICE, 37% of patients by MRI) and the right inferior PV (3% of patients by ICE, 17% of patients by MRI). The sensitivity for esophageal location by ICE compared to that by MRI ranged between 33% (right inferior PV) and 92% (left superior PV antrum, left inferior PV antrum, and mid-posterior wall). The specificity for esophageal location by ICE compared to that by MRI ranged between 60% (mid-posterior wall) and 100% (right inferior PV). The positive predictive value ranged between 80% (left inferior PV) and 100% (right inferior PV). The negative predictive value ranged between 84% (right inferior PV antrum) and 96% (left superior PV antrum). Phased array ICE provides rapid, real-time localization of the esophagus during LA ablation that is comparable to MRI.

Response to Letter Regarding Article “Comparison of Electrode Cooling Between Internal and Open Irrigation in Radiofrequency Ablation Lesion Depth and Incidence of Thrombus and Steam Pop”

We thank Drs Saul and Haemmerich for their comments regarding our article,1 but we respectfully disagree. Using the open-irrigation electrode in clinical practice in the “temperature control” mode with an adequate irrigation flow rate (17 mL/min at ≤30 W and 30 mL/min at 31 to 50 W) infrequently results in reaching the target electrode temperature (ET, 40°C to 45°C). Therefore, radiofrequency (RF) energy is delivered continuously at the power limit (ie, 30 W). This is essentially “power control.” Thrombus did not occur when the closed-loop electrode was used in the 8 RF applications with ET ≤40°C in high blood flow. However, in low blood flow, thrombus …

Endoscopic fiberoptic assessment of balloon occlusion of the pulmonary vein ostium in humans: Comparison with phased-array intracardiac echocardiography

Anatomic pulmonary vein (PV) variants may affect the ability to position balloon catheter systems at the left atrium (LA)-PV junction with complete circumferential contact, resulting in ineffective PV isolation. This feasibility study was performed to assess the use of the fiberoptic endoscopic light ring balloon catheter (ELRBC) in accessing the PVs and achieving adequate contact at the LA-PV junction, as visualized by phased-array intracardiac echocardiography (ICE). We enrolled five men (mean age 59 +/- 8 years) with drug-refractory atrial fibrillation. The ELRBC consisted of a 25-mm balloon catheter with an integral endoscope contained within the balloon and a custom deflectable sheath. At the end of conventional PV isolation, the ELRBC was inserted into the LA in an attempt to position the balloon at each PV ostium. The real position of the ELRBC at this level was assessed by ICE in all patients. All but two PVs (right inferior PVs) (89%) were accessed with the ELRBC in a mean time of 17 +/- 3 minutes, and complete circumferential contact was visualized with the fiberoptic endoscopic component in 15 of 16 PVs accessed (94%). Contact was also confirmed by the absence of color Doppler flow through the balloon-occluded PV, as seen on ICE. On two occasions a gap was seen with the fiberoptic endoscope and visualized by the ICE only after optimization of the echo window. No complications were observed. The ELRBC is able to access the PV without complications. The endoscope and ICE were complementary for positioning of the balloon at the LA-PV junction and for the definition of circumferential contact.

Experience with Intracardiac Echocardiography for Guiding Transcatheter Device Closure of Atrial Septal Defects

Background and Objectives:Phased-array intracardiac echocardiography (ICE) is a novel method for monitoring intracardiac procedures. We report our initial experience with ICE for guiding transcatheter device closure of atrial septal defects (ASD). Subjects and Methods:From April 2004 to March 2005, ICE was performed in 27 consecutive patients during percutaneous device closure of ASDs. The procedural feasibility, the procedure time, the fluoroscopic time, and the complication rate were compared with 27 prior cases that had utilized transesophageal echocardiography. Results:The procedure was performed successfully in all patients. The total procedure time (PT), device deployment time (DT), and fluoroscopic time (FT) were 65.7±22.3, 30.4±23.8, and 12.1±6.4 minutes for the study group, and 73.6±23.7, 29.8±16.1, and 11.9±6.0 for the control group, respectively, with no significant difference between the groups. However, PT and DT were significantly shorter in the later 14 cases of the study group compared to the 13 initial cases (52.1±10.9 and 13.2±4.2 vs. 80.3±22.4 and 48.8±22.2, p< 0.01, respectively). These differences were also significant compared to the control group, suggesting that there was a learning curve for the procedure. Conclusion:ICE is a feasible and relatively safe method for monitoring and guiding percutaneous transcatheter closure of ASDs, but a learning period can be expected to achieve better proficiency. (Korean Circulation J 2006;36:612-616)

Comparison of pulmonary vein ostial diameters by computed tomography and phased array intracardiac echocardiography during radiofrequency ablation of atrial fibrillation

Background: Pulmonary vein (PV) ostial diameters are measured to assist with decisions regarding optimal equipment during ablation of atrial fibrillation and to assess for post ablation stenosis. Knowing the diameter may assist choice of the multipolar loop catheter diameter for ideal mapping and ablation of the arrythmogenic foci at the perimeter of the PV ostia. Fluoroscopic venography relies on projections that may result in inaccurate estimation of PV diameters. Better methods may exist for making these important determinations including helical computerized tomography with 3 dimensional reconstruction (CT) and phased array intracardiac echocardiography (ICE).

A25-2 Feasibility of pulmonary vein isolation guided by phased array intracardiac echocardiography for atrial fibrillation

A25-2 Feasibility of pulmonary vein isolation guided by phased array intracardiac echocardiography for atrial fibrillation