Transesophageal echocardiography to guide pulmonary vein mapping and ablation for atrial fibrillation

Relationship between anatomical characteristics of pulmonary veins and atrial fibrillation recurrence after radiofrequency catheter ablation: a systematic review and meta-analysis

Background

The aim of the current study was to investigate the potential relationship between anatomical characteristics of pulmonary veins (PVs) and atrial fibrillation recurrence (AFR) following radiofrequency catheter ablation (RFCA), specifically focusing on PV diameter and cross-sectional orifices index (CSOA). The analysis was based on a comprehensive review of currently available literature, providing valuable insights for the prevention and treatment of AFR.

Methods

Data was collected from five databases, including PubMed, MEDLINE, EMBASE, and Cochrane, spanning the period from 2004 to October 2022. The search strategy utilized Medical Subject Headings (MeSH) terms related to PV diameter, PV size, PV anatomy, and AFR. Indicators of PV diameter and CSOA from the included studies were collected and analyzed, with Weight mean difference (WMD) and 95% confidence intervals (CIs) representing continuous variables.

Results

The meta-analysis included six studies. The results revealed that patients with AFR had a significant larger mean PV diameter compared to those without AFR (MD 0.33; 95% CI: 0.01, 0.66; P = 0.04; I2 = 33.80%). In a meta-analysis of two studies involving a total of 715 participants, we compared the diameters of the left superior pulmonary vein (LSPV), left inferior pulmonary vein (LIPV), right superior pulmonary vein (RSPV), right inferior pulmonary vein (RIPV) between patients with AFR and patients without AFR. The results showed that there were no statistically significant differences between the two groups in any of the four data items (all P > 0.05). Additionally, the pooled estimate revealed that LSPV-CSOA, LIPV-COSA, RSPV-COSA, and RIPV-CSOA were greater in the AFR group compared to the non-AFR group, but the differences were not statistically significant (all P > 0.05).

Conclusion

We found evidence supporting the notion that the PV diameter of patients who experienced AFR after RFCA was significantly larger than that of patients without AFR. The findings suggested that the PV diameter could serve as a potential predictor of the risk of AFR following RFCA.

Impact of the pulmonary vein orifice area assessed using intracardiac echocardiography on the outcome of radiofrequency catheter ablation for atrial fibrillation

PURPOSE

The purposes of this study were to investigate pulmonary vein cross-sectional orifice area (PV-CSOA) using intracardiac echocardiography (ICE) and to determine its association with atrial fibrillation (AF) recurrence after radiofrequency catheter ablation (RFCA).

METHODS

We studied 77 patients undergoing initial RFCA for AF (55 paroxysmal and 22 persistent AF patients, mean age 61 ± 12 years, 59 men). The PV-CSOA was measured in each patient and expressed as an index divided by the body surface area-left superior (LSPV-CSOA), left inferior (LIPV-CSOA), right superior (RSPV-CSOA), and right inferior (RIPV-CSOA).

RESULTS

After a mean follow-up of 21 ± 14 months, 61 patients maintained sinus rhythm (non-recurrence group) and AF recurred in 16 patients (recurrence group). The LSPV-CSOA index was significantly greater in the recurrence group compared with the non-recurrence group (146 ± 41 vs. 126 ± 30 mm²/m², p = 0.04). A Cox regression multivariate analysis revealed that the LSPV-CSOA was the independent predictor of AF recurrence (HR 1.02, 95% CI 1.01-1.04, p = 0.01). The LSPV-CSOA cutoff value of 154 mm²/m² predicts AF recurrence with 50% positive predictive value and 89% negative predictive value.

CONCLUSIONS

The present study suggests that ICE can be used as an alternative imaging tools for assessing the PV-CSOA during RFCA and that the LSPV-CSOA index was a useful independent predictor of AF recurrence after RFCA.

Transesophageal echocardiography during pulmonary vein cryoballoon ablation for atrial fibrillation

We describe our first 20 cases of cryoablation of atrial fibrillation (AF) using transesophageal echocardiography (TEE). Continuous procedural monitoring with TEE by a cardiologist and senior sonographer assists the electrophysiologist in performance of the cryoballoon procedure of AF. Previously using intracardiac echocardiography (ICE) we have found TEE to have better overall procedural imaging, and monitoring for pericardial effusion or thrombus formation. We have found TEE monitoring to be helpful with positioning for interatrial septal (IAS) puncture, catheter tip avoidance of the left atrial appendage (LAA), and guidance of the balloon catheter into each pulmonary vein (PV), with proper positioning within each PV orifice, and documentation of PV occlusion for the cryoballoon procedure. Procedural equipment and the cryoballoon protocol used are presented in detail. The role of TEE imaging during the procedure and in preventing potential dangers is illustrated. It is the goal of this study to demonstrate how the electrophysiology and echocardiography laboratories work together in this cryoablation procedure.

[Ultrasound in the electrophysiological cardiac catheterization laboratory]

During recent years the need for intraprocedural imaging has increased. Fluoroscopy and angiography are frequently supplemented by pre-procedural magnetic resonance or computed tomography imaging as well as electroanatomic mapping techniques. However, poor real-time imaging quality of soft tissue, radiation exposure, and contrast media consumption are disadvantageous. Ultrasound techniques are characterized by high-quality imaging of soft tissue that can be obtained in real time. All relevant anatomical structures and their relationships to catheters can be evaluated at any time during the procedure. Moreover, functional analysis, e.g., flow measurements and monitoring for complications, is possible. Transesophageal and especially intracardiac echocardiography (ICE) contribute enormously to effectiveness and safety of complex procedures. ICE has been shown to be useful in transseptal procedures like atrial fibrillation ablation but also in ablation procedures for ventricular tachycardias.

Pulmonary vein isolation using a single size cryoballoon chosen according to transesophageal echocardiography information

BACKGROUND

Pulmonary vein isolation (PVI) using cryoballoon (CB) catheter is a new technique for atrial fibrillation (AF) ablation. Previous studies used computer tomography (CT) or magnetic resonance imaging (MRI) scan to determine the pulmonary vein (PV) diameter and anatomy for choosing the CB size. We evaluated pre-ablation transoesophageal-echocardiography (TEE) as an alternative to CT/MRI scan in patients undergoing AF ablation for determining the appropriate size of the CB.

METHODS

Fifty-five consecutive patients (men=43, women=12) with a mean age of 63 ± 12.5 years, and with drug-refractory paroxysmal AF (34 patients) or persistent AF (21 patients) were included in this prospective study. All patients underwent pre-ablation TEE.

RESULTS

Hypertension was present in 19 patients (34%). Mean anterior-posterior left atrium diameter was 45.1 ± 8.9 mm. In total, 217 PV were targeted using a single 23-mm (n=14) or 28-mm (n=40) CB catheter chosen according to TEE-obtained measurements. PVI was achieved in 195 PV (90%). Mean number of CB applications per patient was 9.8 ± 2.1 (range 8-14). Mean procedure duration and fluoroscopy times were 131 ± 27 min (90-190 min) and 36 ± 12 min (22-66 min) respectively. Phrenic nerve palsy occurred in 3 patients (5.4%) and was transient (<1 month) in all of them.

CONCLUSION

This study suggests that TEE is an easily available and effective tool to select the size of the CB for PVI according to evaluated PV diameters and anatomy.

Real-time three-dimensional transesophageal echocardiography for guiding interventional electrophysiology: feasibility study

At present, there are limited methods of acquiring three-dimensional visualization of cardiac structure and function in real-time during interventional electrophysiology procedures. Images acquired for integration of computerized tomography and magnetic resonance imaging with electroanatomic mapping systems are static and are obtained earlier in time. The purpose of this study was to test the feasibility of real-time three-dimensional transesophageal echocardiography for the guidance of interventional electrophysiological studies. A matrix array transducer with 504 channels operating at 5 MHz in a 1 cm diameter steerable esophageal probe was used in conjunction with a scanner capable of real-time 3D scanning of pyramidal volumes from 65 degrees to 120 degrees at rates up to 30 volumes per second. This device has a spatial resolution of approximately 3 mm at 5 cm depth. The authors acquired real-time three-dimensional images of anatomic landmarks of value for electrophysiological procedures in five closed chest canines. Real-time, three-dimensional ultrasound imaging was also used for visualization and guidance of interventional catheter devices within the canine heart. Real-time three-dimensional images of the atria, pulmonary veins, and coronary sinus were acquired. Real-time 3-D color flow Doppler was employed to confirm patency. Multiple image planes of image volumes and rendered views were used to track catheter position and orientation. Images of left veno-atrial junctions have been confirmed by dissection. This study has demonstrated the feasiblity of using real-time three-dimensional transesophageal echocardiography for guiding interventional electrophysiology. The technology has the potential to fill a niche as an adjunct modality for cost-effective real-time interventional guidance and assessment, providing catheter and pacing lead visualization simultaneously with functional volumetric cardiac imaging.

Detection of pulmonary vein stenosis by transesophageal echocardiography: comparison with multidetector computed tomography

OBJECTIVE

The objective of this study is to compare the use of transesophageal echocardiography (TEE) vs multidetector computed tomography (MDCT) for detecting pulmonary vein stenosis.

BACKGROUND

Pulmonary vein isolation is increasingly used to treat atrial fibrillation. Pulmonary vein stenosis remains a potential complication of pulmonary vein isolation and ideal methods for detection of stenosis are still to be determined.

METHODS

Thirty-six subjects who underwent pulmonary vein isolation returned for follow-up MDCT and TEE. Percent diameter loss was reported for each pulmonary vein stenosis by MDCT. A 50% narrowing was considered as an indication of a stenosis. Pulsed-wave Doppler using TEE was used to measure peak velocities of all pulmonary veins.

RESULTS

Multidetector computed tomography and TEE were performed in all subjects (58 +/- 10 years) at 4 +/- 2 months after pulmonary vein isolation. Atrial fibrillation was present in 14% at time of follow-up. Multidetector computed tomography was able to evaluate all 4 (100%) pulmonary veins in 36 subjects, whereas full interrogation by TEE was possible in 138 (96%) of 144 veins. Pulmonary vein stenosis >50% by MDCT was present in 7 pulmonary veins. Analysis of the receiver operating curve for TEE showed that it had optimum detection of pulmonary vein stenosis at peak velocities approximately 100 cm/s with 86% sensitivity and 95% specificity. Area under the curve for TEE was 0.93. Clinically significant stenosis was observed in 2 subjects and was detected by both TEE and MDCT.

CONCLUSIONS

Transesophageal echocardiography was able to detect most pulmonary veins with good sensitivity and specificity in comparison to MDCT. Pulmonary veins may be visualized more frequently by MDCT; however, TEE provides additional data about the functional significance of a pulmonary vein stenosis.

Usefulness of transesophageal echocardiography in the isolation of pulmonary veins in the treatment of atrial fibrillation

BACKGROUND

New imaging strategies for atrial fibrillation (AF) ablation should enhance the safety of this technique. The role of transesophageal echocardiography (TEE) in this setting has not been prospectively evaluated.

METHODS

Under general anesthesia, 85 patients underwent TEE-guided AF ablation. A hybrid technique was performed with circular pulmonary veins (PV) lesions and antrum and ostial electrical isolation guided by TEE. TEE excluded left atrial (LA) thrombus, guided transseptal puncture and catheter positioning, and helped to identify PV ostia and their velocities. The TEE probe localized the esophagus, its temperature (T degrees ) and micro bubbles formation.

RESULTS

Overall, one patient had a LA clot. The esophagus was located close to left PV in 38%, the right PV in 28%, midline in 17% and with an oblique course in 17% of patients. Right and left superior PV velocities were detected in 100%, left inferior PV in 88% and right inferior PV in 82% of patients. Microbubbles were detected in 9 patients (11%). Elevation of TEE T degrees occurred in 14 patients (16%) and was regularly observed when lesions were applied over the TEE probe shadow, in close proximity to the posterior wall. Two major complications (1 tamponade, 1 PV laceration) occurred and were detected early by TEE.

CONCLUSIONS

TEE offers advantages compared to a map-guided only approach. It is a reliable tool to assess esophagus T degrees and localization, guide transseptal puncture, delineate the PV ostia, and monitor complications.

Cardiovascular Imaging in the Management of Atrial Fibrillation

Atrial fibrillation (AF) is he most commonly encountered arrhythmia in clinical practice, with an overall prevalence of 0.4% in the general population. Recent advances in technology and in the understanding of the pathophysiology of AF have led to more definitive and potentially curative therapeutic approaches. Echocardiography has a well-established role in the assessment of cardiac structure and function and risk stratification, and has become an essential part of the guidelines for management of AF. The development of intracardiac echocardiography has led to real-time guidance of percutaneous interventions, including radiofrequency ablation and left atrial appendage closure procedures for patients with AF. Other imaging modalities, including computed tomography and magnetic resonance angiography, have allowed for more accurate measurement and better understanding of the cardiac anatomy. We review the impact of various imaging modalities in the evaluation and management of AF.

Effect of 3D ultrasound probes on the accuracy of electromagnetic tracking systems

In the last few years, 3D ultrasound probes have became readily available. New fields of image-guided surgery applications are opened by attaching small electromagnetic position sensors to 3D ultrasound probes. However, nothing is known about the distortions caused by 3D ultrasound probes regarding electromagnetic sensors. Several trials were performed to investigate error-proneness of state-of-the-art electromagnetic tracking systems when used in combination with 3D ultrasound probes. It was found that 3D ultrasound probes do distort electromagnetic sensors more than 2D probes do. When attaching electromagnetic sensors to 3D probes, maximum errors of 5 mm up to 119 mm occur. The distortion strongly depends on the electromagnetic technology as well on the probe technology used. Thus, for 3D ultrasound-guided applications using electromagnetic tracking technology, the interference of ultrasound probes and electromagnetic sensors have to be checked carefully.

Abnormalities of pulmonary venous flow in patients with lone atrial fibrillation†

AIMS

Mechanisms underlying lone atrial fibrillation (LAF) are poorly defined. We sought to investigate indices of left atrial (LA) function in patients with recurrent LAF, in comparison with that in healthy subjects.

METHODS AND RESULTS

Investigations were performed in 42 patients aged 51.8 +/- 8.7 at least 30 days after the last episode of LAF and in 38 healthy controls. Each subject underwent echocardiographic evaluation including left ventricular parameters and LA function indices. LA ejection fraction served as a measure of LA systolic performance, and acceleration (SAT) and deceleration time (SDT) of systolic phase of pulmonary venous flow (PVF) corresponded to LA relaxation and compliance, respectively. Patients with LAF showed significantly lower values of SAT (179.1 +/- 63.2 vs. 199.2 +/- 45.1 ms, P < 0.02) and higher values of SDT (250.8 +/- 81.6 vs. 211.7 +/- 57.3 ms, P < 0.01) when compared with controls. No significant differences were found with respect to other measured parameters. The combination of SAT < 185 ms and SDT > 239 ms showed a positive predictive value of 92% in the identification of patients prone to LAF.

CONCLUSION

This study suggests that (i) patients with LAF have abnormalities of the systolic phase of PVF and (ii) Doppler estimation of PVF seems to be very valuable in the evaluation of patients with LAF.

Image-based guidance for minimally invasive surgical atrial fibrillation ablation

PURPOSE

Atrial fibrillation (AF) is the most common arrhythmia and results in an increased risk of ischaemic stroke. Recently, a European consortium has developed a new ablation device for minimally invasive surgical AF treatment. The device is controlled by a medical robot. Due to the minimal invasive usage, surgery using the new device needs appropriate navigation support. In this paper, we describe an image-based navigation application to guide the new device intraoperatively.

METHODS

The navigation procedure is based on intraoperative ultrasound. Variations in the position of the ablation device are transferred from the software controlling the robot to the navigation system. Due to the flexibility of the ablation device, a deformation model predicts the behaviour during repositioning. Ablation lines are interactively planned. Actually burned ablation lines are visualized during surgery. Several in vitro and ex vivo experimental set-ups were built up to test the feasibility.

RESULTS

The navigation workflow was implemented into navigation software using well-known open-source software toolkits. The navigation system has been integrated and tested successfully within the overall system. The ablation device could be localized on in vitro and ex vivo ultrasound images.

CONCLUSION

The performed trials proved the applicability of the navigation procedure. More in vivo tests are currently being performed to make the new device and the described navigation procedure ready for clinical use.

Changes of Pulmonary Vein Orifice Size and Location throughout the Cardiac Cycle: Dynamic Analysis Using Magnetic Resonance Cine Imaging

INTRODUCTION

Anatomically guided left atrial ablation is used increasingly for treatment of atrial fibrillation (AF). Three-dimensional mapping systems used for pulmonary veins (PV) encircling ablation procedures anticipate a stable size and position of the PV orifice. The aim of the current study was therefore to analyze changes of PV orifice size and location throughout the cardiac cycle using cine magnetic resonance imaging (MRI).

METHODS AND RESULTS

Twenty-five healthy volunteers were studied using a 1.5 Tesla MRI system. MR angiograms were acquired with a breath-hold three-dimensional fast-spoiled gradient-echo imaging (3D FSPGR) sequence in the coronal plane before and after gadolinium injection. Maximum intensity projections and multiplanar reformations were performed to reconstruct images of the PV. Bright blood cine imaging in the axial view was acquired by a steady-state free precession pulse sequence. Twenty bright blood images were obtained per cardiac cycle. The axial (anterior-posterior) PV orifice diameter was measured in all 20 images. For analysis of PV movement the location of the orifice posterior edge was plotted on scale paper. PV orifice size depends on the stage of the cardiac cycle with the largest diameter in late atrial diastole and a mean decrease of 32.5% during atrial systole. Location changes of the PV orifice are in the range of up to 7.2 mm and larger in the coronal (lateral-medial) than in the sagittal (anterior-posterior) direction.

CONCLUSION

PV orifice size and location is not as stable as anticipated by three-dimensional mapping systems used for PV encircling left atrial ablation procedures. RF application close to the presumed orifice location should therefore be avoided to minimize the risk of PV stenosis.