Intracardiac echocardiography guided anatomical ablation of the arcuate ridge for drug refractory inappropriate sinus tachycardia

INTRODUCTION

Inappropriate sinus tachycardia (IST) is a common condition with frequently not tolerated beta-blockers or ivabradine and a high rate of complication in ablation strategy; we describe an alternative anatomical approach of sinus node (SN) modulation.

METHODS

This retrospective study describes a case series of 6 patients from two centers diagnosed with symptomatic IST undergoing SN ablation.

RESULTS

The mean age was 40.6 ± 13.9 years; five of the six patients were female, 100% of patients reported heart palpitations, and 66% reported dizziness, the average heart rate (HR) on a 24-h Holter was 93.2 ± 7.9 bpm. HR during the first stage of a stress test using a standard Bruce protocol was 150 ± 70 bpm, The average HR on 24-h Holter postablation was 75 ± 5.6 bpm, the sinus rate HR during stage 1 of a Bruce protocol exercise stress test was 120 ± 10 bpm.

CONCLUSION

This is the first case series reporting the acute and long-term results of a novel anatomical approach for SN modulation to treat IST targeting the arcuate ridge (AR) under intracardiac echography (ICE) guidance. The novel anatomic ICE-guided catheter ablation approach aimed to identify the earliest activation at the AR with an extension of RF lesions toward its septal region seems effective and safe to modulate the SN in symptomatic patients with IST refractory to medical treatment.

Dual linear lesions for right atrial flutter after mitral valve surgery via the superior transseptal approach

BACKGROUND

The superior transseptal approach (STA) for mitral valve surgery is associated with a higher risk of developing macroreentrant incisional atrial flutter (AFL) than the left atrial approach. This study aimed to describe the linear lesions for the complex AFL circuit after the STA and to propose an option for the linear ablation target site.

METHODS

Of the 26 patients who underwent radiofrequency catheter ablation for AFL after mitral valve surgery, data from seven patients with STA incisions were retrospectively analyzed.

RESULTS

All patients who had undergone the STA had incisional AFL rotated in a long loop within the right atrium (RA) and cavo-tricuspid isthmus (CTI)-dependent AFL. The linear lesions were created in the CTI, the superior RA vestibule, and between the RA-free wall incision or the septal incision and the inferior vena cava. Procedural success was achieved with dual linear lesions in the CTI and superior RA vestibule. Two of seven patients had AFL recurrence during a mean observation period of 22.5 ± 16.7 months. The circuits of recurrent AFL were CTI-dependent AFL and perimitral AFL, respectively. No AFL recurrence was noted with reconduction of the superior RA vestibular lesion.

CONCLUSION

Dual linear lesions in the CTI and superior RA vestibule are an effective treatment option for RA macroreentrant AFL after the STA.

A highly-detailed anatomical study of left atrial auricle as revealed by in-vivo computed tomography

The left atrial auricle (LAA) is the main source of intracardiac thrombi, which contribute significantly to the total number of stroke cases. It is also considered a major site of origin for atrial fibrillation in patients undergoing ablation procedures. The LAA is known to have a high degree of morphological variability, with shape and structure identified as important contributors to thrombus formation. A detailed understanding of LAA form, dimension, and function is crucial for radiologists, cardiologists, and cardiac surgeons. This review describes the normal anatomy of the LAA as visualized through multiple imaging techniques such as computed tomography (CT), magnetic resonance imaging (MRI), and echocardiography. Special emphasis is devoted to a discussion on how the morphological characteristics of the LAA are closely related to the likelihood of developing LAA thrombi, including insights into LAA embryology.

Anatomic, histologic, and mechanical features of the right atrium: implications for leadless atrial pacemaker implantation

BACKGROUND

Leadless pacemakers (LPs) may mitigate the risk of lead failure and pocket infection related to conventional transvenous pacemakers. Atrial LPs are currently being investigated. However, the optimal and safest implant site is not known.

OBJECTIVES

We aimed to evaluate the right atrial (RA) anatomy and the adjacent structures using complementary analytic models [gross anatomy, cardiac magnetic resonance imaging (MRI), and computer simulation], to identify the optimal safest location to implant an atrial LP human.

METHODS AND RESULTS

Wall thickness and anatomic relationships of the RA were studied in 45 formalin-preserved human hearts. In vivo RA anatomy was assessed in 100 cardiac MRI scans. Finally, 3D collision modelling was undertaken assessing for mechanical device interaction. Three potential locations for an atrial LP were identified; the right atrial appendage (RAA) base, apex, and RA lateral wall. The RAA base had a wall thickness of 2.7 ± 1.6 mm, with a low incidence of collision in virtual implants. The anteromedial recess of the RAA apex had a wall thickness of only 1.3 ± 0.4 mm and minimal interaction in the collision modelling. The RA lateral wall thickness was 2.6 ± 0.9 mm but is in close proximity to the phrenic nerve and sinoatrial artery.

CONCLUSIONS

Based on anatomical review and 3D modelling, the best compromise for an atrial LP implantation may be the RAA base (low incidence of collision, relatively thick myocardial tissue, and without proximity to relevant epicardial structures); the anteromedial recess of the RAA apex and lateral wall are alternate sites. The mid-RAA, RA/superior vena cava junction, and septum appear to be sub-optimal fixation locations.

Computationally Assessed 3D Anatomical Proximities and Spatial Relationships Among the Tricuspid Valve Annulus, Right Coronary Artery, and Triangle of Koch: Implications for Transcatheter Tricuspid Annuloplasty Repair

Background

Transcatheter-based annuloplasty therapies for tricuspid regurgitation have demonstrated significant development over recent years. However, the tricuspid valve and neighboring vasculature and conductive tissue regions can present anatomical and device deployment challenges. This present study investigated the anatomical dimensions and spatial relationships of the cardiac structures essential to percutaneous annuloplasty procedures: the tricuspid annulus (TA), right coronary artery (RCA), and triangle of Koch border region.

Methods

Measurements were derived from computational three-dimensional reconstructions of static magnetic resonance imaging scans of perfusion-fixed human hearts (n = 82) with preserved right-sided heart anatomies. This specimen set included heart samples presenting with prediagnosed atrioventricular valvular regurgitation.

Results

Our anatomical assessments demonstrated that the TA to RCA proximities were intensified with the presence of atrioventricular valvular regurgitation, compared with healthy heart specimens. The minimal distances were frequently located between the lateral and posterior annular points. This annular region corresponds to the RCA distal segments and posterior descending branch origins. Greater portions and incidences of the RCA coursing parallel or inferior to the TA plane were recorded for these diseased hearts. Patient demographic variables (gender, age, and body mass index) were insignificant determinants of change for a majority of our results.

Conclusions

These three-dimensional reconstructions provide insights to guide the development and future iterations of transcatheter tricuspid valve annuloplasty systems with regards to device anchoring, annular geometry, tissue proximities, and implantation considerations.

Mutual Arrangements of Coronary Blood Vessels within the Right Atrial Appendage Vestibule

Background: The aim of our study was to investigate the presence and mutual relationships of coronary vessels within the right atrial appendage (RAA) vestibule. Methods: We examined 200 autopsied hearts. The RAA vestibule was cross-sectioned along its isthmuses (superior, middle, and inferior). Results: The right coronary artery (RCA) was present in 100% of the superior RAA isthmuses but absent in 2.0% of hearts within the middle isthmus and in 6.5% of hearts within the inferior RAA isthmus. Its diameter was quite uniform along the superior (2.6 ± 0.8 mm), middle (2.9 ± 1.1 mm), and inferior (2.7 ± 0.9 mm) isthmuses (p = 0.12). The location of the RCA varied significantly, and it was sometimes accompanied by other accessory coronary vessels. In all the isthmuses, the RCA ran significantly closer to the endocardial surface than to the epicardial surface (p < 0.001). At the superior RAA isthmus, the artery was furthest from the right atrial endocardial surface and this distance gradually decreased between the middle RAA isthmus and the inferior RAA. Conclusions: This study was the most complex analysis of the mutual arrangements and morphometric characteristics of coronary blood vessels within the RAA vestibule. Awareness of additional blood vessels within the vestibule can help clinicians plan and perform safe and efficacious procedures in this region.

EHRA expert consensus statement and practical guide on optimal implantation technique for conventional pacemakers and implantable cardioverter-defibrillators: endorsed by the Heart Rhythm Society (HRS), the Asia Pacific Heart Rhythm Society (APHRS), and the Latin-American Heart Rhythm Society (LAHRS)

With the global increase in device implantations, there is a growing need to train physicians to implant pacemakers and implantable cardioverter-defibrillators. Although there are international recommendations for device indications and programming, there is no consensus to date regarding implantation technique. This document is founded on a systematic literature search and review, and on consensus from an international task force. It aims to fill the gap by setting standards for device implantation.

Morphology and Position of the Right Atrioventricular Valve in Relation to Right Atrial Structures

The right atrioventricular valve (RAV) is an important anatomical structure that prevents blood backflow from the right ventricle to the right atrium. The complex anatomy of the RAV has lowered the success rate of surgical and transcatheter procedures performed within the area. The aim of this study was to describe the morphology of the RAV and determine its spatial position in relation to selected structures of the right atrium. We examined 200 randomly selected human adult hearts. All leaflets and commissures were identified and measured. The position of the RAV was defined. Notably, 3-leaflet configurations were present in 67.0% of cases, whereas 4-leaflet configurations were present in 33.0%. Septal and mural leaflets were both significantly shorter and higher in 4-leaflet than in 3-leaflet RAVs. Significant domination of the muro-septal commissure in 3-leflet valves was noted. The supero-septal commissure was the most stable point within RAV circumference. In 3-leaflet valves, the muro-septal commissure was placed within the cavo-tricuspid isthmus area in 52.2% of cases, followed by the right atrial appendage vestibule region (20.9%). In 4-leaflet RAVs, the infero-septal commissure was located predominantly in the cavo-tricuspid isthmus area and infero-mural commissure was always located within the right atrial appendage vestibule region. The RAV is a highly variable structure. The supero-septal part of the RAV is the least variable component, whereas the infero-mural is the most variable. The number of detected RAV leaflets significantly influences the relative position of individual valve components in relation to right atrial structures.

State-of-the-Art Review: Anatomical and Imaging Considerations During Transcatheter Tricuspid Valve Repair Using an Annuloplasty Approach

Transcatheter techniques for the treatment of tricuspid regurgitation (TR) are being more frequently used and several new devices are in development. Since 90% of patients with TR have secondary TR, catheter based systems which reduce the dilated tricuspid annulus area are of particular interest. In order to perform an annuloplasty procedure effectively and safely, knowledge about the anatomy of the tricuspid valve apparatus and especially of the annulus in relation to the important neighboring structures such as the aortic root, the RCA, the electrical pathways and the CS is fundamental. In addition, comprehensive understanding of the device itself, the delivery system, its maneuverability and the individual procedural steps is required. Furthermore, the use of multi-modality imaging is important. For each step of the procedure the appropriate imaging modality as well as the optimal; imaging planes are crucial to provide the necessary information to best guide the individual procedural step.

Catheter ablation of the left and right atrial appendages without isolation in persistent atrial fibrillation

BACKGROUND

Electrical isolation of the left atrial appendage (LAA) improves outcomes of patients with persistent atrial fibrillation (AF) but may increase the risk of thromboembolism.

OBJECTIVE

The purpose of this study was to describe a method to map and ablate appendage drivers without complete electrical isolation.

METHODS

One hundred thirteen patients underwent an ablation procedure for persistent AF. The procedure was performed during AF and consisted of pulmonary vein and posterior LA isolation as well as ablation of the LAA. The right atrium (RA) was targeted in patients with a right-to-left gradient in cycle length (CL). The end point of appendage ablation was CL slowing or AF termination but not complete isolation.

RESULTS

Among the 113 patients (mean age 64.6 ± 8.6 years; ejection fraction 54% ± 13%; LA diameter 46 ± 6.5 mm), radiofrequency ablation terminated AF in 51 patients (45%). RA ablation was performed in 41 patients (36%) at the index or repeat procedure. The mean AF CL in the RA appendage (RAA) was shorter than that in the LAA (160 ± 32 ms vs 186 ± 29 ms; P < .01) in these patients. The most frequent target in the RA was the RAA (CLs approaching 50-60 ms). Discontinuing radiofrequency ablation upon AF termination or conduction slowing prevented LAA isolation. After a mean follow-up of 24 ± 15 months, 89 patients (78%) remained arrhythmia-free without antiarrhythmic medications.

CONCLUSION

An ablation strategy guided by the AF CL addresses LAA drivers without complete electrical isolation and also helps identify the RAA as a source of persistent AF.

Ablation of Accessory Pathways with Challenging Anatomy

Although catheter ablation of accessory pathways is deemed highly safe and effective, peculiar location of these pathways might lead to complex and potentially hazardous procedures requiring ablation in anatomic regions such as para-Hisian area, coronary sinus, and epicardial surface. The electrophysiologist should know these possible scenarios to plan the best strategy for safe and effective ablation of these uncommon accessory pathways.

Anatomy of the Atrioventricular Junction, Atrioventricular Grooves, and Accessory Pathways

Accessory pathways that bypass all or part of the normal atrioventricular conduction system traverse the atrioventricular junction. The atrioventricular junction comprises of a limited septal component and much more extensive right and left parietal components. Its composition forms a plane of insulation between atrial and ventricular myocardium, preventing direct continuity between them. Typical accessory atrioventricular pathways located anywhere along the atrioventricular junction are muscle bundles or may involve muscle around the walls of coronary sinus aneurysms or coronary veins. Increasingly, variants or unusual accessory pathways, some involving an accessory node, are reported in clinical studies.

Right atrial appendage aneurysm in a fetus-Does precise prenatal diagnosis matter?

Introduction

Congenital malformations of the right atrium-aneurysms and diverticula-are rare heart defects with only a few cases having been described prenatally. Early diagnosis of these anomalies is extremely important due to the possibility of such serious complications such as supraventricular arrhythmia, thromboembolic events and sudden death.

Topic Description

Although each of these anomalies is well known, there are still significant discrepancies in diagnosis. At the same time, there is no essential difference in the postnatal management of patients with right atrial aneurysms or diverticula. Treatment mode varies between centers and is selected individually depending on the presence of symptoms.

Discussion

We discuss the problems of terminology, ultrasound criteria and prenatal differential diagnosis, anatomic and histological features and current limitations for the accurate diagnosis of right atrial aneurysms and diverticula in utero. As a clinical example, we describe a case of right atrial appendage aneurysm diagnosed in a fetus.

Conclusions

Considering the prenatal diagnostic difficulties and similar management of such patients after birth, we suggest avoiding the use of exact terms in the fetus, leaving the precise diagnosis for the postnatal period.

Topographical anatomy of the right atrial appendage vestibule and its isthmuses

INTRODUCTION

The right atrial appendage (RAA) vestibule is an area located in the right atrium between the RAA orifice and the right atrioventricular valve annulus and may be a target for invasive transcatheter procedures.

METHODS AND RESULTS

We examined 200 autopsied human hearts. Three isthmuses (an inferior, a middle, and a superior isthmus) were detected. The average length of the vestibule was 67.4 ± 10.1 mm. Crevices and diverticula were observed within the vestibule in 15.3% of specimens. The isthmuses had varying heights: superior: 14.0 ± 3.4 mm, middle: 11.2 ± 3.1 mm, and inferior: 10.1 ± 2.7 mm (p < .001). The superior isthmus had the thickest atrial wall (at midlevel: 16.7 ± 5.6 mm), the middle isthmus had the second thickest wall (13.5 ± 4.2 mm), and the inferior isthmus had the thinnest wall (9.3 ± 3.0 mm; p < .001). This same pattern was observed when analyzing the thickness of the adipose layer (superior isthmus had a thickness of 15.4 ± 5.6 mm, middle: 11.7 ± 4.1 mm and inferior: 7.1 ± 3.1 mm; p < .001). The average myocardial thickness did not vary between isthmuses (superior isthmus: 1.3 ± 0.5 mm, middle isthmus: 1.8 ± 0.8 mm, inferior isthmus: 1.6 ± 0.5 mm; p > .05). Within each isthmus, there were variations in the thickness of the entire atrial wall and of the adipose layer. These were thickest near the valve annulus and thinnest near the RAA orifice (p < .001). The thickness of the myocardial layer followed an inverse trend (p < .001).

CONCLUSIONS

This study was the first to describe the detailed topographical anatomy of the RAA vestibule and that of its adjoining isthmuses. The substantial variability in the structure and dimensions of the RAA isthmuses may play a role in planning interventions within this anatomic region.

Imaging for Tricuspid Valve Repair and Replacement

Primary or secondary tricuspid regurgitation (TR) represents an important health care burden and challenge which has often been neglected or undertreated in the past. The expansion and reinforcement of the indications for tricuspid valve (TV) intervention in the 2017 editions of the guidelines as well as the introduction of transcatheter tricuspid valve intervention (TTVI) has considerably increased the attention of the community on the TV and the volume of TV interventions in the past years. Depending on the anatomic target, TTVI can be categorized as the following: 1) direct or indirect tricuspid restrictive annuloplasty; 2) direct (edge-to-edge repair) or indirect (coaptation device) restoration of leaflet coaptation; 3) heterotopic tricuspid valve implantation; and 4) transcatheter tricuspid valve replacement. Multimodality imaging has crucial role for the following: 1) patient selection for TTVI and procedure planning; 2) guiding and monitoring the procedure; and 3) assessing and following over time the results of the procedure. The key points for pre-procedural imaging are: 1) accurate quantitation of TR severity; 2) proper identification of the mechanism(s) responsible for the TR; and 3) quantitation of RV dysfunction and pulmonary arterial hypertension. This imaging work-up is essential to select the right type of intervention for the right patient and TV. Transesophageal echocardiography and fluoroscopy imaging is also key for guiding the TTVI procedures and fusion between these 2 modalities may further enhance the quality of procedure guiding.

Right Atrioventricular Valve Leaflet Morphology Redefined: Implications for Transcatheter Repair Procedures

OBJECTIVES

The authors aimed to comprehensively detail the right atrioventricular valve functional leaflet anatomies.

BACKGROUND

The rapid development of both surgical and percutaneous repair techniques for tricuspid regurgitation has renewed interest in variations in the morphology of the right atrioventricular valve.

METHODS

The functioning right atrioventricular valves of 40 reanimated human hearts were imaged using Visible Heart methodologies. Hearts were then perfusion-fixed and dissected, uniquely allowing for the comparative assessments of functional versus fixed valve anatomies from the same set of donor hearts.

RESULTS

The right atrioventricular valves have "3-leaflet" configurations in 57.5% and "4-leaflet" configurations in the remaining hearts. For 4-leaflet valves, extra leaflets were commonly observed in the most inferior regions of the annuli. No difference in valve perimeters between 2 valve types were observed (112.2 vs. 117.1 mm; p = 0.14). In 3-leaflet valves, septal, mural, and superior leaflets occupied 32.2 ± 6.5%, 15.9 ± 5.5%, and 25.5 ± 6.2% of the annulus, respectively, whereas in the 4-leaflet arrangements, these values were 27.0 ± 5.8% (septal), 12.0 ± 4.5% (inferior), 13.7 ± 9.4% (mural), and 19.8 ± 6.1% (superior). The muroseptal/inferoseptal commissures were usually located in the cavotricuspid regions, whereas the inferomural and superomural commissures were in the right atrial appendage vestibule area.

CONCLUSIONS

The right atrioventricular valve has 4 functional leaflets in more than 40% of cases. The authors found that the inferomural region is the most variable area of the valve and believe that anatomic variation is an important consideration for planned interventions.

Checking the shape and lobation of the right atrial appendage in view of their clinical relevance

Clinically, anatomy of the appendage of the atrium is associated with atrial fibrillation, with the shape and lobation of the appendage having been used to stratify the risk of thromboembolic events. The aim of this study was to examine the age-dependent change in the shape and lobation of the right atrial appendage. A cross-sectional evaluation of the heart of 172 adults and 61 children, fixed in 4% formalin solution was performed. The morphology of the atrial appendage was assessed based on its shape and number of lobes. The following shapes of the appendage were identified: horse head, parrot beak, anvil, sailboat, and undefined. Using the horse head shape as a reference, the risk for a thromboembolic event was higher for anvil, sailboat and undefined shapes of the appendage (p < 0.001). The number of lobes ranged between 1 and 6 in adults, and 1 and 5 in children. The number of lobes for each shape was equivalent between adults and children (p > 0.05). Our analysis indicated that the number of lobes and the distribution of shapes of the atrial appendage remained unchanged throughout life. The risk for a thromboembolic event increased with the morphological complexity of the appendage (anvil, sailboat, and undefined), with 21% of adult hearts being prone to intra-atrial thrombosis in cases of fibrillation.

Computed tomography for planning transcatheter tricuspid valve therapy

Aims

Percutaneous transcatheter tricuspid valve therapy is an evolving treatment option for patients with significant tricuspid regurgitation (TR) deemed too fragile for open heart surgery. The present study proposes comprehensive anatomical evaluation of the tricuspid valve, right ventricle (RV), and vena cavae and its spatial relationships with the right coronary artery (RCA) using computed tomography (CT) and investigates the implications for suitability for current technologies.

Methods and results

A total of 250 patients (mean age 80 ± 7.2 years, 52.4% men) undergoing CT were divided according to the presence of moderate or severe TR (≥3+, n = 40) and less than moderate TR (<3+, n = 210). Tricuspid valve annulus, RV, and vena cavae dimensions and the course of the RCA relative to the tricuspid annulus were evaluated. Patients with TR ≥ 3+ showed significantly larger dimensions of the tricuspid annulus, RV and vena cavae. In 64.8% of patients, the RCA coursed along the tricuspid valve annulus. Patients with TR <3+ showed more frequently a course of the RCA superior to the tricuspid annulus at the levels of the anterior and the posterior tricuspid leaflet compared with their counterparts (12.4% vs. 0%, P = 0.019). A less favourable course of the RCA (≤2.0 mm distance to the annulus) for current annuloplasty techniques was observed at the level of the anterior tricuspid and posterior leaflets in respective 12.5 and 27.5% of patients with TR ≥3+.

Conclusion

The present study proposes a first systematic approach based on CT to define the patient suitability for current transcatheter tricuspid valve devices.

Anatomy of the Tricuspid Valve, Pathophysiology of Functional Tricuspid Regurgitation, and Implications for Percutaneous Therapies

The tricuspid valve is a complex dynamic apparatus made up of many different closely linked structures: the annulus, the three leaflets, the chordae, the papillary muscles and the right ventricle. Other nearby structures, such as the coronary sinus ostium, the conduction system, the membranous septum, and the right coronary artery must be taken into account when dealing with the tricuspid. Annulus dilation and leaflet tethering due to right ventricular remodeling are the 2 major mechanisms responsible for most tricuspid regurgitation cases. Precise knowledge of tricuspid anatomy and function, as well as careful preoperative planning, is fundamental for successful transcatheter tricuspid procedures.

Bands, Chords, Tendons, and Membranes in the Heart: An Imaging Overview

Crests, bands, chords, and membranes can be seen within the different cardiac chambers, with variable clinical significance. They can be incidental or can have clinical implications by causing hemodynamic disturbance. It is crucial to know the morphology and orientation of normal structures, aberrant or accessory muscles, and abnormal membranes to diagnose the hemodynamic disturbance associated with them. Newer generation computed tomographic scanners and faster magnetic resonance imaging sequences offer high spatial and temporal resolution allowing for acquisition of high resolution images of the cardiac chambers improving identification of small internal structures, such as papillary muscles, muscular bands, chords, and membranes. They also help in identification of other associated complications, malformations, and provide a road map for treatment. In this article, we review cross-sectional cardiac imaging findings of normal anatomical variants and distinctive imaging features of pathologic bands, chords, or membranes, which may produce significant hemodynamic changes and clinical symptomatology.

Successful cryoablation of an incessant atrial tachycardia arising from the right atrial appendage

The right atrial appendage can be the origin of focal atrial tachycardias. Their ablation can be challenging owing to the complexity of the appendage anatomy. To our knowledge, we describe the first successful solid tip cryoablation of a focal tachycardia within the right atrial appendage in a patient presenting with tachycardia-induced cardiomyopathy.