Transseptal left heart catheterisation guided by intracardiac echocardiography

Radiofrequency Catheter Septal Ablation via a Trans-Atrial Septal Approach Guided by Intracardiac Echocardiography in Hypertrophic Obstructive Cardiomyopathy: One-Year Follow-Up

Background

Percutaneous radiofrequency catheter ablation (RFA) in hypertrophic obstructive cardiomyopathy (HOCM) with intracardiac echocardiography (ICE) guidance is a novel method that has been proven to be safe and effective in a small sample size study. RFA of the interventricular septum through a trans-atrial septal approach in HOCM patients with a longer follow-up has not been reported.

Methods

62 consecutive patients from March 2019 to February 2022 were included in this study. The area between the hypertrophied septum and anterior mitral valve (MV) leaflet was established using the three-dimensional system (CARTO 3 system), and all patients received atrial septal puncture under the guidance of intracardiac echocardiography (ICE). Point-by-point ablation was performed to cover the contact area. After ablation, the patients were followed up for 1, 3, 6, and 12 months. Transthoracic echocardiography was performed at 1, 3, 6, and 12 months, and resting and exercise-provoked left ventricular outflow tract (LVOT) gradients were obtained.

Results

During the 1-year follow-up, most patients' symptoms improved. The NYHA grading of the patient decreased from 2 (2, 3) at baseline to 2 (1, 2) (p < 0.001). LVOT peak gradient at rest was decreased from 59 ( ± 27) mmHg to 30 ( ± 24) mmHg (p < 0.001), and the provoked peak gradient was decreased from 99 ( ± 33) mmHg to 59 ( ± 34) mmHg (p < 0.001). The average maximum septal thickness was reduced from 21 ( ± 4) mm to 19 ( ± 4) mm (p < 0.001).

Conclusions

After a 1-year follow-up, ice-guided radiofrequency ablation for HOCM might be a safe, accurate, and effective method. The catheter might be reliably attached to the ablation target area via trans-atrial septal access.

Direct ICE imaging from inside the left atrial appendage during ablation of persistent atrial fibrillation

We present the case of a 59-year-old patient with persistent atrial fibrillation, referred for atrial fibrillation ablation. The procedure was performed with the help of NAVX 3D mapping system (Saint Jude Medical) and iLAB Ultra ICE Plus ultrasound imaging catheter (Boston Scientific). The catheter permits cross-sectional images perpendicular to catheter's long axis. From inside left atrial appendage (LAA) looks trabeculated, due to pectinate muscles running parallel to each other. The presence of a thrombus was excluded from the appendage. The contractility of LAA was also assessed using multiple frames recorded on videotape. Our case demonstrates that LAA's morphology and function can be directly assessed by intracardiac ultrasound with the probe inserted inside the appendage.

Wire- and needle potentials facilitating transseptal puncture

BACKGROUND

Transseptal puncture for left heart interventions became a routine procedure guided by fluoroscopy and echocardiography. The use of intracardiac potentials derived from the sheath-transseptal-needle/guidewire-combination may provide helpful information to increase safety of this procedure.

METHODS AND RESULTS

We recorded the intracardiac potentials from the sheath-transseptal-needle/guidewire-combination during the transseptal puncture procedure in 31 consecutive patients (mean age 67.2±8.2years; 21 in sinus rhythm, 10 in atrial fibrillation) designated for ablation of atrial fibrillation by the Cryo-balloon ® technique (Medtronic, Minnesota, USA). The EP-Navigator ® 3-D-image integration tool (Philips Healthcare, Hamburg, Germany) was used for visualization of the device position in relation to the cardiac structures. Typical and reproducible potentials could be derived in all patients for the different device localizations at transseptal puncture procedure. Especially the transition from the muscular interatrial septum into the fossa ovalis could be easily depicted by the changes of both morphology and magnitude of the atrial signal (6.1±2.3mV in sinus rhythm [SR]/3.5±0.9mV in atrial fibrillation [AF] at the muscular interatrial septum and 0.5±0.2mV in SR/0.5±0.1mV in AF in the fossa ovalis).

CONCLUSIONS

The crucial steps of a transseptal procedure can be verified by typical changes (morphology and amplitude) of the intracardiac signals derived from the sheath-transseptal-needle/guidewire-combination in patients with sinus rhythm as well as in atrial fibrillation.

Latest advances in transseptal structural heart interventions-Percutaneous Mitral Valve Repair and Left Atrial Appendage Occlusion

Recent advances in structural heart intervention have produced increasing demand for transseptal access, which was first introduced as a diagnostic tool to directly measure left atrial pressure. Transseptal access allows safe and adequate approach to the left atrium and surrounding structures. Percutaneous transcatheter mitral valve repair using the MitraClip device is a safe and less invasive treatment for selected patients with significant mitral regurgitation, who are at high risk for surgery. This is an echocardiographic- and fluoroscopic-guided procedure requiring accurate transseptal access of the left atrium and clipping of the mitral leaflets at the precise location of their malcoaptation. Percutaneous transcatheter closure of the left atrial appendage is another novel procedure that requires transseptal access of the left atrium, followed by closure or ligation of the left atrial appendage. This catheter-based therapy has been shown to be a safe and effective alternative to long-term anticoagulant therapy for the prevention of stroke in patients with atrial fibrillation. In this article, we systematically review these novel structural heart interventions.

Added value of transoesophageal echocardiography during transseptal puncture performed by inexperienced operators

AIMS

Transseptal puncture (TP) appears to be safe in experienced hands; however, it can be associated with life-threatening complications. The aim of our study was to demonstrate the added value of routine use of transoesophageal echocardiography (TEE) for the correct positioning of the transseptal system in the fossa ovalis, thus potentially preventing complications during fluoroscopy-guided TP performed by inexperienced operators.

METHODS AND RESULTS

Two hundred and five patients undergoing pulmonary vein isolation procedure (PVI) for drug-resistant paroxysmal or persistent atrial fibrillation were prospectively included. When the operator (initially blinded to TEE) assumed that the transseptal system was in a correct position according to fluoroscopical landmarks, the latter was then checked with TEE unblinding the physician. If necessary, further refinement of the catheter position was performed. Refinement >10 mm, or in case of catheter pointing directly at the aortic root or posterior wall were considered as major repositioning. Thirty-four patients required major repositioning. Regression analysis revealed age (P: 0.0001, Wald: 12.9, 95% confidence interval: 1.04-1.16), left atrial diameter (P: 0.01, Wald: 6.6, 95% confidence interval: 1.04-1.34), previous PVI (P: 0.01, Wald: 6.3, 95% confidence interval: 1.31-8.76), and atrial septal thickness (P: 0.03, Wald: 4.5, 95% confidence interval: 1.05-3.4) as independent predictors of major revision with TEE.

CONCLUSION

Routine 2D TEE in addition to traditional fluoroscopic TP appears to be very useful to guide the TP assembly in a correct puncture position and thus, to avoid TP-related complications. However, further randomized prospective comparative studies are necessary to support these suggestions.

Assisted circulation using the TandemHeart during very high-risk PCI of the unprotected left main coronary artery in patients declined for CABG

OBJECTIVES

In a single center experience, we retrospectively evaluated the short-term safety and efficacy of the TandemHeart percutaneous transseptal left ventricular assist (PTVA) system to deliver extracorporeal circulatory support during catheter based treatment of the unprotected left main coronary artery (ULMCA).

BACKGROUND

Percutaneous Coronary Intervention (PCI) of the ULMCA usually has been restricted to patients who are hemodynamically unstable or ineligible for coronary artery bypass grafting (CABG). High-risk patients for CABG should be considered at increased risk for PCI as well. In these patients the TandemHeart PTVA System (p-LVAD) may provide a valuable safeguard to reduce procedural risks.

METHODS AND RESULTS

Between July 2002 and May 2008 the TandemHeart was used in 9 very high risk patients (Logistic Euro score: 13.64 (7.46-29.67); Syntax score:43 (41-50); Mayo Clinic Risk score (MCRS) 7 (6-8); age: median 65 (range 55-71) undergoing elective PCI for the novo lesions on the ULMCA. All patients were declined for CABG by a heart team. A ''true'' percutaneous insertion technique was used in all patients, technical success rate was 100%. The median (range) time for implementation of circulatory support was 27 min (24-30). A median (range) pump flow up to 4.36 (3.40-5.54) L/min was achieved with significant reduction of left ventricular filling pressures, pulmonary capillary wedge pressure and a small increase of systemic arterial pressures. Median (range) duration of support was 93 min (50.4-102). Successful weaning was achieved in all patients. There was no in hospital death, survival at 6 months was (89%), whereas vascular access site complications were seen in 4 patients (44.4%).

CONCLUSIONS

In very high risk PCI, assisted circulation using the TandemHeart-PTVA provides effective, total left ventricular support and may contribute to a reduced procedural risk and improved survival. The rate of device related cardiac and vascular complications was acceptable.

Echocardiography-guided interventions

A major advantage of echocardiography over other advanced imaging modalities (magnetic resonance imaging, computed tomographic angiography) is that echocardiography is mobile and real time. Echocardiograms can be recorded at the bedside, in the cardiac catheterization laboratory, in the cardiovascular intensive care unit, in the emergency room-indeed, any place that can accommodate a wheeled cart. This tremendous advantage allows for the performance of imaging immediately before, during, and after various procedures involving interventions. The purpose of this report is to review the use of echocardiography to guide interventions. We provide information on the selection of patients for interventions, monitoring during the performance of interventions, and assessing the effects of interventions after their completion. In this document, we address the use of echocardiography in commonly performed procedures: transatrial septal catheterization, pericardiocentesis, myocardial biopsy, percutaneous transvenous balloon valvuloplasty, catheter closure of atrial septal defects (ASDs) and patent foramen ovale (PFO), alcohol septal ablation for hypertrophic cardiomyopathy, and cardiac electrophysiology. A concluding section addresses interventions that are presently investigational but are likely to enter the realm of practice in the very near future: complex mitral valve repairs, left atrial appendage (LAA) occlusion devices, 3-dimensional (3D) echocardiographic guidance, and percutaneous aortic valve replacement. The use of echocardiography to select and guide cardiac resynchronization therapy has recently been addressed in a separate document published by the American Society of Echocardiography and is not further discussed in this document. The use of imaging techniques to guide even well-established procedures enhances the efficiency and safety of these procedures.

The magnetic navigation system allows avoidance of puncturing a baffle during ablation of a postincisional macroreentrant tachycardia

An 18-year-old female patient with tricuspid atresia, discordant ventriculo-arterial connections, a total cavo-pulmonary connection, and a Damus-Kaye-Stansel suffered with atrial tachycardia. Use of a magnetically navigated catheter made it possible to create an electro-anatomical map of both atriums using a retrograde approach. It then proved possible to ablate successfully the tachycardia in the left atrium thanks to the unique capabilities of the magnetic navigation system.

Atrial Septal Defect and Atrial Fibrillation: The Known and Unknown

Atrial fibrillation (AF) is a common complication in patients with atrial septal defects (ASDs). The link between AF and ASD is fairly complex and entails modifications in electrophysiologic, contractile and structural properties, at the cellular and tissue level, of both atria, mainly due to chronic atrial stretch and dilation. Surgical repair or percutaneous closure of ASDs are equally effective in reducing mortality and symptoms but limited in preventing or curbing AF, unless combined with an arrhythmia-specific procedure. Transesophageal echocardiography (TEE) and intracardiac echocardiography (ICE) have improved the safety and success of the above procedures. Finally, clearer understanding of the pathophysiology of AF in patients with ASD (and CHF, in general) has led to target-specific advances in medical management.

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.

[Treatment of arrhythmias associated with congenital heart disease using transcatheter ablation]

Rhythm disturbances are common long after surgical repair of congenital heart disease. These arrhythmias caused by the progression of the disease itself, however, a significant proportion is a result of the presence of surgical scar. Although interventional electrophysiology procedures are complex and encounter difficulties, pharmacological therapy is often very disappointing.

AIM AND METHODS

In the present study we aimed to describe our experience obtained between 2004 and 2006 in patients undergoing transcatheter ablation long after surgery for congenital heart disease.

RESULTS

During this period 26 patients underwent catheter ablation. The procedure was successful in 24 out of the 26 patients (92%). Three patients required redo ablations due to arrhythmia recurrences (11%). There were no major complications related to the intervention. In four patients minor complications occurred (small hematomas).

CONCLUSIONS

Our descriptive data indicate that transcatheter ablation for arrhythmias after surgery for congenital heart disease is a effective safe and more importantly curative procedure. It is associated with reasonable success rate, low complication rate, but slightly higher recurrence rate as compared to the classical electrophysiological interventions.

Value of CT localization of the fossa ovalis prior to transseptal left heart catheterization for left atrial ablation

AIMS

Transseptal puncture (TP) can be a difficult procedure and is not without risk of complications. The purpose of this study was to evaluate the use of three-dimensional multi-detector row computed tomography (MDCT) to localize the fossa ovalis (FO) and facilitate TP in patients undergoing left atrial catheter ablation.

METHODS AND RESULTS

Fourteen consecutive patients were studied. Thirteen patients underwent pulmonary vein isolation and one patient had ablation for left atrial flutter. All patients underwent cardiac MDCT imaging pre-ablation for use in conjunction with electroanatomic mapping. Prior to puncturing the interatrial septum, standard fluoroscopic views of the transseptal sheath were compared with corresponding MDCT images tagging the FO. Successful, uncomplicated TP was achieved in all 14 patients. The mean duration of TP was 15.6 +/- 10.0 min. The average fluoroscopy time was 8.5 +/- 7.4 min. The MDCT images were deemed helpful in facilitating TP in 13 patients (93%).

CONCLUSION

This study demonstrates the feasibility of MDCT to localize the FO and aid TP. For patients undergoing left atrial ablation in whom MDCT imaging is undertaken pre-ablation, tagging the FO can be easily performed and is a novel tool for guiding transseptal catheterization without additional risk.

Right atrial angiography facilitates transseptal puncture for complex ablation in patients with unusual anatomy

OBJECTIVE

The number of transseptal punctures performed worldwide has increased exponentially with the development of ablation therapies for atrial arrhythmias. Safe access into the left atrium in these procedures is often complicated by abnormal anatomy. We assessed the potential of right atrial angiography to facilitate transseptal puncture for atrial ablation.

METHODS AND RESULTS

We examined all transseptal punctures performed for complex left atrial ablation in our centre over a 29-month period. In cases where conventional transseptal techniques failed, we performed orthogonal right atrial angiography to define cardiac anatomy and orientation. During the study period, 255 transseptal procedures were performed. Of these, 16 cases were complicated by distorted atrial anatomy, extreme cardiac rotation or unexpected location of the atria in relation to the diaphragm, preventing left atrial access using conventional fluoroscopy. The application of right atrial angiography facilitated successful transseptal puncture in all patients when use of conventional mapping catheters and fluoroscopy proved unhelpful. There were no complications relating to right atrial angiography.

CONCLUSION

These cases highlight a number of difficulties encountered when performing transseptal punctures. Previously reported adjunctive techniques require specialised equipment, general anaesthesia or multiple catheters that may be unavailable or impede the procedure. Right atrial angiography is a simple and safe adjunct to conventional techniques to facilitate complex transseptal procedures.

Trans-septal catheterization in the electrophysiology laboratory: data from a multicenter survey spanning 12 years

OBJECTIVES

We report the data from the Italian Survey on trans-septal catheterization (TSP-C) for catheter ablation of arrhythmias in the left heart that covered 2003 and previous years.

BACKGROUND

Over the last decade the use of TSP-C in the electrophysiology laboratory has greatly increased. Recent data on number of procedures, accomplishment rate, and complications related to this procedure are lacking in a large cohort of patients.

METHODS

Thirty-three centers participated in the survey. The data collected retrospectively for 2003 included the number of procedures, indications, methods, and the number and reason for unaccomplished cases along with complications. Retrospective data collected for previous years included the annual number of procedures and cumulative data concerning indications, accomplishments, and complications.

RESULTS

Since 1992, 5,520 TSP-C procedures were used in arrhythmia ablation, with the peak increase in the use occurring in 2001. Trans-septal catheterization was performed for atrial fibrillation (AF) ablation in 78.3% of the procedures in 2003. The electrophysiologist independently performed the procedure in 29 of 33 centers. Trans-septal catheterization was successfully performed in 99.1% of the cases; the main reason for TSP-C not being performed was related to fossa ovalis/atrial septum anatomy. Complications were low both in 2003 and in the previous years (0.79% and 0.74%, respectively).

CONCLUSIONS

Trans-septal catheterization in the electrophysiology laboratory is associated with a high success and low complication rate. The use of TSP-C has progressively increased over the last decade and is currently used primarily for AF ablation. Although possible, severe complications were rare.

Intracardiac Ultrasound Detection of Thrombus on Transseptal Sheath: Incidence, Treatment, and Prevention

BACKGROUND

Transseptal (TS) catheterization is used for left atrial (LA) ablation procedures and a major risk is thromboembolism. The purpose of this study was to assess (1) the value of intracardiac ultrasound (ICUS) monitoring during LA ablation procedures, and (2) a new technique to reduce the risk of thrombus formation.

METHODS AND RESULTS

One hundred and eighty consecutive patients underwent TS catheterization under ICUS guidance with two sheaths for atrial fibrillation ablation and one for other LA procedures. Group I included the initial 90 patients in whom TS sheaths were flushed with a standard 2 U/cc concentration of heparin; group II consisted of the next 90 patients in whom sheaths were flushed with 1,000 U/cc concentration. All patients received bolus and infusion of heparin to maintain ACT between 250-300 seconds. ICUS was monitored throughout. In group I, echodense material at the tip of the sheath consistent with thrombus was observed on ICUS in 8 of 90 patients (9%) within 5-15 minutes of entering the LA. In group II, only 1 of 90 patient (1%) demonstrated thrombus (P < 0.001). There were no significant clinical differences in group I patients with and without thrombus. In all nine patients, the clot was removed with vigorous aspiration. No patients suffered a neurological event.

CONCLUSION

Thrombus formation on TS sheath, detected by ICUS, may be more common than expected despite adequate anticoagulation. Using a higher concentration of heparin for the TS system before deployment reduced the risk. The thrombus was retrieved with aspiration without the need to abort the procedure.

Preventing complicated transseptal puncture with intracardiac echocardiography: case report

Background

Recently, intracardiac echocardiography emerged as a useful tool in the electrophysiology laboratories for guiding transseptal left heart catheterizations, for avoiding thromboembolic and mechanical complications and assessing the ablation lesions characteristics. Although the value of ICE is well known, it is not a universal tool for achieving uncomplicated access to the left atrium. We present a case in which ICE led to interruption of a transseptal procedure because several risk factors for mechanical complications were revealed.

Case presentation

A case of a patient with paroxysmal atrial fibrillation and atrial flutter, and distorted intracardiac anatomy is presented. Intracardiac echocardiography showed a small oval fossa abouting to an enlarged aorta anteriorly. A very small distance from the interatrial septum to the left atrial free wall was seen. The latter two conditions were predisposing to a complicated transseptal puncture. According to fluoroscopy the transseptal needle had a correct position, but the intracardiac echo image showed that it was actually pointing towards the aortic root and most importantly, that it was virtually impossible to stabilize it in the fossa itself. Based on intracardiac echo findings a decision was made to limit the procedure only to ablation of the cavotricuspid isthmus and not to proceed further so as to avoid complications.

Conclusion

This case report illustrates the usefulness of the intracardiac echocardiography in preventing serious or even fatal complications in transseptal procedures when the cardiac anatomy is unusual or distorted. It also helps to understand the possible mechanisms of mechanical complications in cases where fluoroscopic images are apparently normal.

Sixteen multidetector row computed tomography of pulmonary veins: 3-months' follow-up after treatment of paroxysmal atrial fibrillation with cryothermal ablation

The aim of the study was to assess pulmonary veins (PVs) for the presence of stenosis 3 months after cryothermal ablation (CA) with a new method of electrical isolation of PVs using contrast-enhanced 16 multidetector row computed tomography (MDCT). Twenty four patients with symptomatic atrial fibrillation underwent CA in 46 PVs. MDCT of PVs was performed before the treatment and after 3-months' follow-up. Following cryoablation, 13/24 (54%) patients showed clinical improvement and had reduced attacks of atrial fibrillation. The dimensions of the treated PVs remained unchanged: the coronal ostial diameter was 19.1+/-2.4 preprocedural versus 18.6+/-2.4 mm at follow-up, p>0.05; the ratio of the coronal and axial diameters at the ostium was 1.2+/-0.2 versus 1.2+/-0.1, p>0.05, respectively, and the coronal diameter of the proximal 10 mm was 17.1+/-2.5 mm versus 16.5+/-2.2 mm, p>0.05, respectively. CA is a promising technique for electrical isolation of PVs that has not been associated with stenosis at the orifice and the proximal 10 mm of the PVs after 3-months' follow-up. MDCT is a noninvasive, fast and comfortable method for assessment of PVs in a three-dimensional manner prior to ablative treatment and during the follow-up.

Visualization of elusive structures using intracardiac echocardiography: insights from electrophysiology

Electrophysiological mapping and ablation techniques are increasingly used to diagnose and treat many types of supraventricular and ventricular tachycardias. These procedures require an intimate knowledge of intracardiac anatomy and their use has led to a renewed interest in visualization of specific structures. This has required collaborative efforts from imaging as well as electrophysiology experts. Classical imaging techniques may be unable to visualize structures involved in arrhythmia mechanisms and therapy. Novel methods, such as intracardiac echocardiography and three-dimensional echocardiography, have been refined and these technological improvements have opened new perspectives for more effective and accurate imaging during electrophysiology procedures. Concurrently, visualization of these structures noticeably improved our ability to identify intracardiac structures. The aim of this review is to provide electrophysiologists with an overview of recent insights into the structure of the heart obtained with intracardiac echocardiography and to indicate to the echo-specialist which structures are potentially important for the electrophysiologist.

Catheter-based intracardiac echocardiography in the interventional cardiac laboratory

Recent advances in technology have engendered a renewed enthusiasm in the use of intracardiac echocardiography (ICE) to guide and assess cardiac interventions. AcuNav is a phased-array sector imaging probe equipped with color and spectral Doppler capabilities. Previous-generation imaging catheters yielded unfamiliar limited-depth radial images with no flow information. Current imaging technology such as the AcuNav has not only consolidated the role of ICE but opened newer applications in the interventional laboratory. ICE has clear advantages over transesophageal echocardiography as the imaging modality of choice in the cardiac catheterization and electrophysiological laboratories. We review the technical evolution of ICE and describe the expanded utility of the AcuNav imaging catheter during cardiac interventions.

First Dutch experience with percutaneous left atrial appendage transcatheter occlusion

BACKGROUND

Patients with atrial fibrillation (AF) have an increased risk of thromboembolic stroke, dependent on clinical variables. Oral anticoagulation significantly decreases the risk of stroke or embolism, but sometimes this is difficult to manage and may be contraindicated. Approximately 90% of atrial thrombi in nonrheumatic AF are found in the left atrial appendage (LAA). A new device has been developed which allows percutaneous LAA occlusion (PLAATO) and might be an alternative to oral anticoagulation. Feasibility in dogs and humans was described previously.

METHODS AND RESULTS

As part of an international multicentre trial, three patients received a percutaneous transcatheter LAA occlusion device. Implantations were performed without general anaesthesia, guided by intracardiac and transoesophageal echocardiography and without major complications. The implantations were well tolerated by the patients, who entered a long-term follow-up to be compared with a historical control group.

CONCLUSION

Transseptal percutaneous LAA occlusion is feasible. Its role as an alternative to oral anticoagulation, however, needs to be further defined.

Electrical isolation of pulmonary veins using cryothermal energy: study design and initial results

BACKGROUND

Atrial fibrillation (AF) is the most frequently encountered arrhythmia. Radiofrequency pulmonary vein (PV) ablation is promising for symptomatic paroxysmal AF, but is associated with a significant risk of PV stenosis.

OBJECTIVES

To assess the efficacy of cryothermal PV ablation and the incidence of PV stenosis.

METHODS

Highly symptomatic patients with paroxysmal or persistent AF were eligible for cryothermal ablation. Multislice spiral CT scans were performed before, and three months after ablation. AF burden was assessed using transtelephonic ECG recording and by telephonic enquiry.

RESULTS

An attempt was made to isolate 27 PVs in 15 patients. In total, 20 PVs could be isolated (74% acute success). No significant difference in PV diameter was seen before and after ablation. Five out of 12 patients with paroxysmal AF were completely without AF after one ablation procedure. An additional two patients reported a significant reduction in symptoms. In the three patients with persistent AF no improvement was reported.

CONCLUSION

Cryothermal PV ablation was effective in isolation of the targeted PVs. It appears to be safe, as no PV stenosis was seen in this study three months after the ablation. Taking into account a learning curve, we consider the clinical results to be very promising.

Effects of septal pacing on P wave characteristics: the value of three-dimensional echocardiography

Interatrial septum (IAS) pacing has been proposed for the prevention of paroxysmal atrial fibrillation. IAS pacing is usually guided by fluoroscopy and P wave analysis. The authors have developed a new approach for IAS pacing using intracardiac echocardiography (ICE), and examined its effects on P wave characteristics. Cross-sectional images are acquired during pullback of the ICE transducer from the superior vena cava into the inferior vena cava by an electrocardiogram- and respiration-gated technique. The right atrium and IAS are then three-dimensionally reconstructed, and the desired pacing site is selected. After lead placement and electrical testing, another three-dimensional reconstruction is performed to verify the final lead position. The study included 14 patients. IAS pacing was achieved at seven suprafossal (SF) and seven infrafossal (IF) lead locations, all confirmed by three-dimensional imaging. IAS pacing resulted in a significant reduction of P wave duration as compared to sinus rhythm (99.7 +/- 18.7 vs 140.4 +/- 8.8 ms; P < 0.01). SF pacing was associated with a greater reduction of P wave duration than IF pacing (56.1 +/- 9.9 vs 30.2 +/- 13.6 ms; P < 0.01). P wave dispersion remained unchanged during septal pacing as compared to sinus rhythm (21.4 +/- 16.1 vs 13.5 +/- 13.9 ms; NS). Three-dimensional intracardiac echocardiography can be used to guide IAS pacing. SF pacing was associated with a greater decrease in P wave duration, suggesting that it is a preferable location to decrease interatrial conduction delay.

Interatrial septum pacing guided by three-dimensional intracardiac echocardiography

OBJECTIVES

Currently, the interatrial septum (IAS) pacing site is indirectly selected by fluoroscopy and P-wave analysis. The aim of the present study was to develop a novel approach for IAS pacing using intracardiac echocardiography (ICE).

BACKGROUND

Interatrial septum pacing may be beneficial for the prevention of paroxysmal atrial fibrillation.

METHODS

Cross-sectional images are acquired during a pull-back of the ICE transducer from the superior vena cava into the inferior vena cava by an electrocardiogram- and respiration-gated technique. Both atria are then reconstructed using three-dimensional (3D) imaging. Using an "en face" view of the IAS, the desired pacing site is selected. Following lead placement and electrical testing, another 3D reconstruction is performed to verify the final lead position.

RESULTS

Twelve patients were included in this study. The IAS pacing was achieved in all patients including six suprafossal (SF) and six infrafossal (IF) lead locations all confirmed by 3D imaging. The mean duration times of atrial lead implantation and fluoroscopy were 70 +/- 48.9 min and 23.7 +/- 20.6 min, respectively. The IAS pacing resulted in a significant reduction of the P-wave duration as compared to sinus rhythm (98.9 +/- 19.3 ms vs. 141.3 +/- 8.6 ms; p < 0.002). The SF pacing showed a greater reduction of the P-wave duration than IF pacing (59.4 +/- 6.6 ms vs. 30.2 +/- 13.6 ms; p < 0.004).

CONCLUSIONS

Three-dimensional ICE is a feasible tool for guiding IAS pacing.

The development and evaluation of a three-dimensional ultrasound-guided breast biopsy apparatus

We have designed a prototype three-dimensional ultrasound guidance (3D USB) apparatus to improve the breast biopsy procedure. Features from stereotactic mammography and free-hand US-guided biopsy have been combined with 3D US imaging. This breast biopsy apparatus accurately guides a needle into position for the sampling of target tissue. We have evaluated this apparatus in three stages. First, by testing the placement accuracy of a needle in a tissue mimicking phantom. Second, with tissue mimicking phantoms that had embedded lesions for biopsy. Finally, by comparison to free-hand US-guided biopsy, using chicken breast phantoms. The first two stages of evaluation quantified the mechanical biases in the 3D USB apparatus. Compensating for these, a 96% success rate in targeting 3.2 mm "lesions" in chicken breast phantoms was achieved when using the 3D USB apparatus. The expert radiologists performing biopsies with free-hand US guidance achieved a 94.5% success rate. This has proven an equivalence between our apparatus, operated by non-experts, and free-hand biopsy performed by expert radiologists, for 3.2 mm lesions in vitro, with a 95% confidence.

Ablation of atrial fibrillation

Associated with significant morbidity and mortality, atrial fibrillation is one of the most common cardiac rhythm disorders. Cure of this arrhythmia has been elusive over the years, despite development of different antiarrhythmic drugs and advances in the understanding of its pathophysiology. Initial experience with catheter ablation procedures based on the creation of linear lesions in both atria has been disappointing, but has led to the key observation that focal triggers localized in the pulmonary veins are responsible for initiation of atrial fibrillation, and thus are suitable targets for catheter ablation. With advances in technology and larger experience, it has become clear that electrical isolation of all four pulmonary veins from the left atrium provides the higher cure rates. However, the procedure is still operator dependent and is associated with a small but significant risk of pulmonary vein stenosis. Further simplification of the isolation techniques and refinement in the catheter design will allow more widespread use of this procedure and higher success rate.