Interatrial septal puncture without the use of fluoroscopy—reducing ionizing radiation in left atrial ablation procedures

Ablation for atrial fibrillation is now widespread and may involve the delivery of relatively high doses of ionizing radiation to both patients and operators. Until now, atrial septal puncture has mandated the use of either fluoroscopy or additional expensive imaging modalities for its safe deployment. We describe a novel technique using the EnSite NavX three-dimensional imaging system for visualization of the transseptal needle throughout the puncture-without the need for either fluoroscopy or additional imaging. This may be important in reducing the need for fluoroscopy for left atrial ablation procedures.     

Localization of fossa ovalis and Brockenbrough needle prior to left atrial ablation using three-dimensional mapping with EnSite Fusion™

Background  

Transseptal catheterization of the interatrial septum has traditionally been performed under the guidance of fluoroscopy, echocardiography, and hemodynamic pressure monitoring. We hypothesized that the fossa ovalis could be identified on pre-ablation chest computerized tomography (CT) scan utilizing EnSite Verismo™ and Fusion™ software thereby permitting its real-time visualization during transseptal puncture.     

Learning process for transseptal puncture guided by intracardiac echocardiography

We prospectively analyzed the learning process for transseptal catheterization guided by intracardiac echocardiography, in 50 patients who underwent radiofrequency ablation for left atrial arrhythmias. In 20 patients the intracardiac echocardiography catheter was positioned in the right atrium to visualize the fossa ovalis and the tenting of the fossa caused by the Brockenbrough needle. In the other 30 patients, the intracardiac echocardiography catheter was positioned so that it impinged upon the fossa ovalis, and the needle was advanced alongside the intracardiac echocardiography catheter under fluoroscopic guidance in two orthogonal projections. In all but one patient, transseptal catheterization was performed successfully on the first attempt. The learning process for transseptal puncture guided by intracardiac echocardiography was uncomplicated, resulting in a procedure that is safe and effective. The intervention is simplified by positioning the echocardiography catheter at the fossa ovalis and using this as a reference point for fluoroscopic monitoring of the progress of the Brockenbrough needle.     

Nonfluoroscopic Transseptal Catheterization:

ICE-Guided Transseptal Catheterization. Introduction : Recently, there has been a revival in the use of transseptal catheterization due to the development of balloon mitral valvuloplasty and radiofrequency catheter ablation. Complications of transseptal puncture, although rare, can be serious and life-threatening. In the present study, we evaluated the use of intracardiac echocardiography (ICE) as the sole imaging modality to guide transseptal puncture and catheterization.
Methods and Results : In each animal. 10 transseptal punctures were performed guided solely by ICE. The standard approach to transseptal catheterization using a Brockenbrough needle and long vascular sheath was used except for the use of ICE instead of fluoroscopy. A 6.2-French/12.5-MHz and 9-Frencb/9-MH7, ICE catheter was used for imaging. At the end of each study, pathologic evaluation was performed. Transseptal puncture was performed safely, guided solely by ICE, in each of 100 attempts (five attempts guided by each ICE catheter in 10 dogs). While the fossa ovalis was easily visualized with both ICE catheters, the 9-Frcnch/9-MHz catheter offered an enhanced field of view. On pathologic evaluation, there was no evidence of perforation of either the right or left atrium outside of the fossa ovalis.
Conclusion : Both ICE catheters used in this trial allowed for excellent visualization of the fossa ovalis and safe transseptal puncture. Intracardiac echocardiography may be a better imaging modality than fluoroscopy for guiding transseptal atheterization, especially in less experienced hands.     

Transseptal Catheterization with Transesophageal Guidance in High Risk Patients

Atrial transseptal catheterization is usually performed with fluoroscopic guidance of the needle. We report our experience with both fluoroscopic and transesophageal guidance in patients who would otherwise have been at risk by using only fluoroscopy. A total of eleven procedures were performed during a 4 year period. The relative contraindications (some patients had several contraindications) included prior valve replacement (5 patients), prior myocardial revascularization (4 patients), severe dilatation of the left atrium (4 patients), severe dilatation of the ascending aorta (4 patients), and kyphoscoliosis (3 patients). All eleven patients had the transesophageal guided transseptal catheterization performed without complications and without significantly prolonging the procedure. The results of this preliminary, small, and retrospective study suggest that transesophageal echocardiography may enhance the safety of transseptal catheterization in high risk patients. Further prospective studies are needed.     

3-Dimensional Transseptal Puncture Based on Electrographic Characteristics of Fossa Ovalis: A Fluoroscopy-Free and Echocardiography-Free Method

ObjectivesThis study sought to define electrographic characteristics of the fossa ovalis (FO) and use these findings in developing a 3-dimensional (3D) transseptal puncture (TSP) technique that does not rely on fluoroscopy or echocardiography.BackgroundTraditional TSP method based on fluoroscopy or echocardiography is basically a 2-dimensional (2D) technique. A valid 3D method of TSP has not been sufficiently clarified.MethodsThe shape of the FO and its center were “electrographically” defined by comparing their potential characteristics to those of the surrounding limbus. After validation by intracardiac echocardiography, this FO mapping was incorporated into 3D electroanatomical reconstruction of the right atrium. Using a new catheter connection, the transseptal needle could be visualized nonfluoroscopically and directed to the precise localization of the FO on the electroanatomic map.ResultsA total of 276 patients who underwent atrial fibrillation ablation were included. The central FO was identified in all cases with atrial electrogram voltage at 0.33 ± 0.21 mV. The amplitude of atrial potential at the FO annulus was 1.70 ± 0.72 mV (p < 0.001). By incorporating the electrographically defined FO into the 3D electroanatomic mapping and using the transseptal needle visualization approach, TSP was successful in all patients, with 91% of the cases at the first attempt. Atrial fibrillation ablation was completed in all patients with no major complication.ConclusionsElectrographic characteristics of the FO center are distinct from those of the surrounding regions. This information can be leveraged to define the FO on 3D electroanatomic mappings, thereby facilitating safe TSP without the need of ancillary imaging with fluoroscopy or echocardiography.     

Intracardiac echocardiography to guide transseptal left heart catheterization for radiofrequency catheter ablation

INTRODUCTION: The purpose of this study was to assess the feasibility and safety of intracardiac echocardiography to guide transseptal puncture for radiofrequency catheter ablation. METHODS AND RESULTS: Transcatheter intracardiac echocardiography (9 MHz) was utilized to guide transseptal puncture in 53 patients undergoing radiofrequency catheter ablation. The anatomy and relationship of intra- and extracardiac structures were visualized with the ultrasound transducer positioned at the fossa ovalis. The tip of the transseptal dilator and tenting of the fossa ovalis and the left atrial wall were simultaneously visualized in a single ultrasound image in all patients. With maximum tenting of the fossa ovalis, the mean distance from the fossa to the left atrial wall was 11.9 +/- 5.8 mm (range: 1.8 to 25.6 mm). In four patients (8%), the tented fossa ovalis abutted the left atrial wall and the transseptal dilator was redirected with ultrasound guidance. Puncture of the interatrial septum was achieved through the fossa ovalis in each patient and required a single attempt in 51 patients (96%). The mean number of punctures per patient was 1.1 +/- 0.4. The mean time to perform transseptal catheterization was 18.2 +/- 6.8 minutes. There were no complications. CONCLUSION: Intracardiac echocardiography delineated the anatomy of intra- and extracardiac structures not identified with fluoroscopy and simplified correct positioning of the transseptal dilator, puncture of the fossa ovalis, and cannulation of the left atrium in a timely and uncomplicated fashion.     

Transseptal left heart catheterisation guided by intracardiac echocardiography

OBJECTIVE—To develop a novel approach of transseptal puncture guided by intracardiac echocardiography and to assess its efficacy.
METHODS—Transcatheter intracardiac echocardiography with a 9 MHz rotating transducer was performed to guide transseptal puncture in 12 patients (mean age 43.1 years, range 31-68) who underwent radiofrequency catheter ablation of left sided accessory pathways. Initially, the echocardiography and transseptal catheters were placed adjacent to each other in the superior vena cava and were withdrawn to the level of the fossa ovalis.
RESULTS—The successful puncture site was associated with visualisation of the fossa ovalis (12 patients, 100%) and the aorta (12 patients, 100%), tenting of the fossa (six patients, 50%), penetration of the needle visualised by the ultrasound catheter (12 patients, 100 %), and echocardiographic contrast material applied in the left atrium (12 patients, 100%). The characteristic jump of the needle onto the fossa ovalis was observed simultaneously with fluoroscopy and intracardiac ultrasound (12 patients, 100%). All procedures were successful. There were no complications associated with the transseptal procedure.
CONCLUSIONS—Intracardiac echocardiography is feasible to guide transseptal puncture. The optimal puncture site can be assessed by simultaneous detection of the characteristic downward jump of the transseptal needle onto the fossa ovalis by intracardiac ultrasound and fluoroscopy.


Keywords: intracardiac echocardiography; transseptal catheterisation     

Einsatz des Navigationssystems NavX® bei der Ablationsbehandlung von Vorhofflimmern

Catheter ablation, notably the electric isolation of pulmonary veins, has become a well-established therapeutic approach in symptomatic atrial fibrillation. The NavX navigation system has been described to facilitate pulmonary vein isolation in patients with AF. EnSite NavX (Endocardial Solutions, St. Jude Medical, Inc., St. Paul, MN, USA) is a novel navigation system that measures the local voltage on every standard intra-cardiac electrode and calculates the electrode position in three-dimensional (3D) space. Any individual electrode of each catheter in 3D-space can be displayed and labelled individually. The geometry of any cardiac chamber can be reconstructed and additional information, e.g. electrical activation spreading, can be displayed colour coded on the surface. Recent studies investigating the possible advantages of this system in the ablation of persistent or paroxysmal atrial fibrillation are summarized. All reports showed a significant reduction in fluoroscopy and procedure time by the use of the NavX system compared to conventional fluoroscopic catheter guidance. This benefit can be obtained with simple visualisation of all intracardiac catheters alone or with additional reconstruction of the left atrium and pulmonary veins.     

Intraoperative characterization of interventricular mechanical dyssynchrony using electroanatomic mapping system—a feasibility study

Background

Interventricular mechanical dyssynchrony (VVMD) is a strong predictor of cardiac resynchronization therapy (CRT) response. However, no simple and reliable clinical method of measuring VVMD during CRT implant is currently available. We tested the hypothesis that the EnSite? NavX? system (St. Jude Medical, St. Paul, MN, USA) can be used intraoperatively to determine VVMD, thereby facilitating CRT optimization.

Methods

During CRT implant, the leads in the right atrium (RA), right ventricle (RV), and left ventricle (LV) were connected to the EnSite? NavX? system to record the real-time 3D motion of the lead electrodes. The distances from RA to RV lead electrodes (RA–RV) and RA to LV lead electrodes (RA–LV) were computed over ten cardiac cycles during each of RV pacing and biventricular (BiV) pacing, respectively. The degree of synchrony was computed from the distance waveforms between RA–RV and RA–LV by a cross-covariance method to characterize VVMD. Septal-to-posterior wall motion delay (SPWMD) from M-mode echocardiography (echo) was measured for reference at each pacing intervention. VVMD was present in all five patients undergoing CRT implant.

Results

Four of the five patients demonstrated clear improvement in EnSite? NavX?-derived VVMD during BiV versus RV pacing, which corresponded to the SPWMD results by echo.

Conclusions

It is feasible to characterize VVMD and resynchronization in CRT patients with the EnSite? NavX? system during implant, demonstrating its potential as a tool for intraoperative CRT optimization.     

A radiofrequency transseptal needle: Initial animal studies

Objectives: The objective of this study was to demonstrate the safety and efficacy of a new transseptal needle design with a radiofrequency (RF) tip combined with the ease of use of the needle configuration. Background: RF transseptal puncture to enter the left heart, with a RF wire‐catheter system is a successful technique in patients with complex access using a standard transseptal needle. Methods: The RF transseptal needle (NRG? Transseptal Needle; Baylis Medical, Montreal, Canada) was designed for RF percutaneous transseptal access to the left heart. Eight pigs underwent transvenous cardiac catheterization with baseline intracardiac electrograms and right atrial pressure waveforms. Transseptal RF puncture was performed followed by left atrial pressure waveform monitoring. Results: An intracardiac electrogram was recorded in each animal while dragging the needle tip from the superior caval vein across the atrial septum and into the inferior caval vein. Contrast staining of the atrial septum was accomplished in all animals, with subsequent RF septal puncture. After 0.1 sec, impedance increased from 300 to 1,200 Ohms with the creation of a vapor layer, and voltage increased steadily to a threshold of 230 volts over the first 0.4 sec. This dielectric breakdown results in tissue vaporization and tissue perforation. The needle's location within the left atrium was confirmed by the pressure waveform and contrast injection. Repeated RF punctures with the NRG? was compatible with various manufactures transseptal sheaths. Conclusion: RF puncture of the interatrial septum using the NRG? Transseptal Needle facilitates an alternative effective technique to enter the left atrium. © 2010 Wiley‐Liss, Inc.     

Rationale and design of the NO-PARTY trial: near-zero fluoroscopic exposure during catheter ablation of supraventricular arrhythmias in young patients

Introduction Radiofrequency catheter ablation is the mainstay of therapy for supraventricular tachyarrhythmias. Conventional radiofrequency catheter ablation requires the use of fluoroscopy, thus exposing patients to ionising radiation. The feasibility and safety of non-fluoroscopic radiofrequency catheter ablation has been recently reported in a wide range of supraventricular tachyarrhythmias using the EnSite NavX? mapping system. The NO-PARTY is a multi-centre, randomised controlled trial designed to test the hypothesis that catheter ablation of supraventricular tachyarrhythmias guided by the EnSite NavX? mapping system results in a clinically significant reduction in exposure to ionising radiation compared with conventional catheter ablation. METHODS: The study will randomise 210 patients undergoing catheter ablation of supraventricular tachyarrhythmias to either a conventional ablation technique or one guided by the EnSite NavX? mapping system. The primary end-point is the reduction of the radiation dose to the patient. Secondary end-points include procedural success, reduction of the radiation dose to the operator, and a cost-effectiveness analysis. In a subgroup of patients, we will also evaluate the radiobiological effectiveness of dose reduction by assessing acute chromosomal DNA damage in peripheral blood lymphocytes. CONCLUSIONS: NO-PARTY will determine whether radiofrequency catheter ablation of supraventricular tachyarrhythmias guided by the EnSite NavX? mapping system is a suitable and cost-effective approach to achieve a clinically significant reduction in ionising radiation exposure for both patient and operator.     

Limiting left-sided catheter dwelling time using 3-D NavX to mark and reaccess the left atrium via prior transseptal puncture site

Introduction

Ablations requiring transseptal access to the left heart place patients at increased risk for stroke, bleeding, and post-procedural cognitive dysfunction and other complications. Diminishing left atrial catheter dwelling time may decrease these risks. 3-D NavX can be used to facilitate reaccess of transseptal puncture sites to allow catheter removal from the left atrium immediately after ablation, with reaccess through the prior transseptal site if required. Here, we describe the techniques employed and our experience using 3-D NavX to limit left atrial catheter dwelling time by marking and reaccess of the left atrium via the previously marked transseptal puncture site, a potentially radiation-free technique.

Methods

With the use of 3-D NavX, a right atrial geometry is created. The patent foramen ovale is marked by using a standard EP catheter, or the transseptal puncture site is marked using 3-D NavX by creating a unipolar electrode on the transseptal needle at the time of puncture and at the time of catheter withdrawal of the ablation catheter from the left atrium. Marking the access site allows the catheter to be removed from the left side of the heart immediately after the ablation. If reaccess to the left atrium is required, the previously marked transseptal site is used to navigate the ablation catheter to reaccess the left atrium. All patients <30 years who had undergone this technique were evaluated. Data gathered included patient demographics, need for and success of transseptal reaccess, left atrial catheter dwelling time, and complications.

Results

The transseptal site was marked by 3-D NavX in 54 patients. We were able to successfully reaccess the transseptal puncture site using 3-D guidance in all 10 patients where it was desired. In these 54 patients, the complication rate was low with one small post-procedural pulmonary embolism and one right bundle branch block. No other complications were noted. The median procedure time was 105 min (range 58–446 min), the median total fluoroscopic time for the entire procedure was 1.3 min (range 0.0–30.8 min), and the median left-sided catheter dwelling time was 21 min (range 6–112 min).

Conclusions

In our retrospective review, reaccess of transseptal puncture site was reproducible, and early removal of the catheter from the left side was without the need for repeat transseptal punctures. This technique decreases the time the catheter dwells in the left atrium, which could decrease risks such as clotting, bleeding, and cognitive dysfunction.     

Transseptal catheterization technique: a simple safety procedure

The major complication of transseptal catheterization, that of inadvertent perforation of other structures, can best be avoided by maintenance of the correct needle tip position during introduction and maneuvering of the assembly. The addition of a needle-stop to the transseptal needle shaft and a sterile ruler to check its present position assures the maintenance of the needle tip position, freeing the operator's concern for accurate location of landmarks. The method of utilizing and setting the needle-stop is described.     

Interventional Echocardiography

Echocardiography guidance for interventions in the catheterization laboratory allows for reduction in radiation exposure from fluoroscopy as well as superior anatomic definition and visualization. The additional information provided over fluoroscopy has translated into an increasing use during interventional procedures. Procedures such as transeptal puncture, percutaneous valvular interventions, myocardial biopsy, echo-guided pericardiocentesis and other interventions have evolved to a complexity level that requires combined echocardiographic and fluoroscopic guidance. Different imaging modalities are utilized in the catheterization laboratory including intracardiac echocardiography, two-dimensional (2D) or three-dimensional (3D) transthoracic echocardiography, and 2D or 3D transesophageal echocardiography. This review is intended to provide an overall summary of the impact echocardiography has had in the catheterization laboratory. We will describe how echocardiography is utilized to guide a diverse array of interventional procedures, emphasizing specific practical issues with respect to echocardiographic guidance of interventional procedures and also pointing out the limitations of echocardiography.     

Balloon and blade atrial septostomy facilitated by two-dimensional echocardiography

Two-dimensional echocardiography (2-D echo) was used as an imaging device for the performance of balloon atrial septostomy (n = 25) and blade atrial septostomy (n = 3). Biplane fluoroscopy with 2-D echo or 2-D echo alone were used in the cardiac catheterization laboratory to place the balloon or blade septostomy catheter in the left atrium. Echocardiography confirmed the position of the septostomy catheter before pullback. Balloon inflation and balloon or blade pullback to the right atrium was performed with 2-D echocardiographic visualization. In 8 critically ill newborn infants, balloon atrial septostomy was done in the neonatal intensive care unit without flouroscopy. The safety and efficacy of 2-D echo to assist balloon or blade atrial septostomy in the catheterization laboratory or as the sole imaging device in the neonatal intensive care unit are confirmed. Use of the subcostal 4-chamber and sagittal views to image cardiac anatomy and catheter position during the procedure are emphasized. Two-dimensional echo is particularly helpful in cases of cardiac malposition and during transseptal puncture of the atrial septum before blade septostomy, and lowers radiation dose when used in conjunction with fluoroscopy.     

Visualization of multiple catheters in left atrial ablation procedures

Background

Visualization of intracardiac catheters placed in predefined anatomic locations is a cornerstone for successful atrial fibrillation (AF) ablation. The 3D mapping system Carto3? (Biosense Webster, Diamond Bar, CA, USA) released in 2009 provides the possibility to visualize more than one intracardiac catheter at a time. The aim of the study was to evaluate the feasibility and safety of the system, to show the learning curve, and to compare it to the established Ensite NavX? system regarding procedural handling parameters.

Methods

A total of 100?patients were enrolled in the study. The Carto3? system was used by a team of four specialized operators in 50?patients (mean age 62±9?years, paroxysmal AF n=28, persistent AF n=17, left atrial flutter n=5). Patients were consecutively enrolled and matched (regarding type of ablated arrhythmias, ablation strategy, left atrial size, age, and gender) with patients ablated during the same time period with the EnSite NavX? system. In patients with paroxysmal AF, ostial pulmonary vein isolation (PVI) was performed. Patients with persistent AF underwent PVI plus additional ablation of complex fractionated atrial electrograms (CFAE) and patients with left atrial flutter were treated with specific lines.

Results

In 50?case-control pairs, all procedures were performed as planned without complications in both groups except one?cardiac tamponade in 1?patient in the Ensite NavX? control group. The learning curve using the Carto3? system was fast regarding x-ray time and procedural duration and reached the level of the EnSite NavX? system after 15?and 25?patients, respectively.

Conclusion

The Carto3? system with its feature of visualizing several catheters is feasible and safe compared to an established system, e.g., Ensite NavX?. The learning curve is steep regarding reduction of x-ray time and procedural duration.     

Fossa ovalis radiofrequency perforation in a difficult case of conventional transseptal puncture for atrial fibrillation ablation

A 65-year-old man was referred for atrial fibrillation ablation to our center. Routine pre-procedure transthoracic and transoesophageal echocardiography and cardiac computed tomography examinations showed a normal interatrial septum and fossa ovalis anatomy. Access to left atrium was initially planned using a conventional transseptal needle puncture. During the procedure, several consecutive attempts in conjunction with intracardiac echocardiography support, failed to cross the septum. The procedure was then successfully carried out using a specifically designed radiofrequency transseptal catheter.     

Intracardiac echocardiography during radiofrequency catheter ablation of cardiac arrhythmias in humans

Objectives. The purpose of this study was to describe our preliminary experience using catheter-based intracardiac echocardiography as an adjunct to biplane fluoroscopy for guiding radiofrequency catheter ablation of atrial arrhythmias in the right side of the heart.Background. Catheter ablation requires precise positioning and stable ablation electrode-endocardial contact. This procedure is currently guided by an analysis of intracardiac electrograms and fluoroscopy. However, the use of fluoroscopy does not allow the endocardium and certain anatomic landmarks to be identified and is associated with the hazards of radiation exposure.Methods. Seventeen symptomatic patients were studied. A 10F 10-MHz intracardiac imaging catheter was used to visualize specific anatomic landmarks in the right atrium for directing the ablation electrode in 15 patients undergoing radiofrequency ablation of 19 arrhythmias and to assist with interatrial septal puncture in 3 patients.Results. Continuous intracardiac imaging was performed for a mean ± SD of 63.6 ± 39.2 min and demonstrated distal electrode-endocardial tissue contact in 81 (60%) of 134 radiofrequency applications. Movement of the catheter was demonstrated during 36 (44%), microcavitations during 39 (48%) and thrombus during 15 (19%) of the 81 imaged applications. In 7 of 10 procedures for atrial flutter, successful ablation was directed at anatomic corridors in the right atrium visualized with intracardiac echocardiography. During ablation of atrial tachycardia, imaging identified abnormal atrial anatomy related to previous surgery and guided successful ablation of a reentrant tachycardia circulating around these anatomic obstacles. In two procedures for slow pathway modification of atrioventricular node reentrant tachycardia, intracardiac echocardiography confirmed catheter stability at the tricuspid annulus anterior to the coronary sinus.Conclusions. During catheter ablation, intracardiac echocardiography augments fluoroscopy by visualizing anatomic landmarks, ensuring stable endocardial contact and assisting in transseptal puncture. Ablation of typical atrial flutter can be successfully directed at anatomic corridors identified using intracardiac imaging.     

Transseptal puncture guided by intracardiac echocardiography during percutaneous transvenous mitral commissurotomy in patients with distorted anatomy of the fossa ovalis.

Positioning of the transseptal needle during percutaneous transvenous mitral commissurotomy (PTMV) can become a difficult and risky procedure when distortion of the interatrial septum exists. We present two cases where intracardiac echocardiography (ICE) facilitated the transseptal puncture in the presence of bulging of the fossa ovalis into the right atrium.