Anatomy of the true interatrial septum for transseptal access to the left atrium

2024 European Heart Rhythm Association/Heart Rhythm Society/Asia Pacific Heart Rhythm Society/Latin American Heart Rhythm Society expert consensus statement on catheter and surgical ablation of atrial fibrillation

In the last three decades, ablation of atrial fibrillation (AF) has become an evidence-based safe and efficacious treatment for managing the most common cardiac arrhythmia. In 2007, the first joint expert consensus document was issued, guiding healthcare professionals involved in catheter or surgical AF ablation. Mounting research evidence and technological advances have resulted in a rapidly changing landscape in the field of catheter and surgical AF ablation, thus stressing the need for regularly updated versions of this partnership which were issued in 2012 and 2017. Seven years after the last consensus, an updated document was considered necessary to define a contemporary framework for selection and management of patients considered for or undergoing catheter or surgical AF ablation. This consensus is a joint effort from collaborating cardiac electrophysiology societies, namely the European Heart Rhythm Association, the Heart Rhythm Society (HRS), the Asia Pacific HRS, and the Latin American HRS.

2024 European Heart Rhythm Association/Heart Rhythm Society/Asia Pacific Heart Rhythm Society/Latin American Heart Rhythm Society expert consensus statement on catheter and surgical ablation of atrial fibrillation

In the last three decades, ablation of atrial fibrillation (AF) has become an evidence-based safe and efficacious treatment for managing the most common cardiac arrhythmia. In 2007, the first joint expert consensus document was issued, guiding healthcare professionals involved in catheter or surgical AF ablation. Mounting research evidence and technological advances have resulted in a rapidly changing landscape in the field of catheter and surgical AF ablation, thus stressing the need for regularly updated versions of this partnership which were issued in 2012 and 2017. Seven years after the last consensus, an updated document was considered necessary to define a contemporary framework for selection and management of patients considered for or undergoing catheter or surgical AF ablation. This consensus is a joint effort from collaborating cardiac electrophysiology societies, namely the European Heart Rhythm Association, the Heart Rhythm Society, the Asia Pacific Heart Rhythm Society, and the Latin American Heart Rhythm Society.

Optimizing transseptal puncture guided by three-dimensional mapping: the role of a unipolar electrogram in a needle tip

AIMS

A three-dimensional electroanatomic mapping system-guided transseptal puncture (3D-TSP), without fluoroscopy or echocardiography, has been only minimally reported. Indications for 3D-TSP remain unclear. Against this background, this study aims to establish a precise technique and create a workflow for validating and selecting eligible patients for fluoroless 3D-TSP.

METHODS AND RESULTS

We developed a new methodology for 3D-TSP based on a unipolar electrogram derived from a transseptal needle tip (UEGM tip) in 102 patients (the derivation cohort) with intracardiac echocardiography (ICE) from March 2018 to February 2019. The apparent current of injury (COI) was recorded at the muscular limbus of the foramen ovalis (FO) on the UEGM tip (sinus rhythm: 2.57 ± 0.95 mV, atrial fibrillation: 1.92 ± 0.77 mV), which then disappeared or significantly reduced at the central FO. Changes in the COI, serving as a major criterion to establish a 3D-TSP workflow, proved to be the most valuable indicator for identifying the FO in 99% (101/102) of patients compared with three previous techniques (three minor criteria) of reduction in atrial unipolar or bipolar potential and FO protrusion. A total of 99.9% (1042/1043) patients in the validation cohort underwent successful 3D-TSP through the workflow from March 2019 to July 2023. Intracardiac echocardiography guidance was required for 6.6% (69/1042) of patients. All four criteria were met in 740 patients, resulting in a 100% pure fluoroless 3D-TSP success rate.

CONCLUSION

In most patients, fluoroless 3D-TSP was successfully achieved using changes in the COI on the UEGM tip. Patients who met all four criteria were considered suitable for 3D-TSP, while those who met none required ICE guidance.

2024 European Heart Rhythm Association/Heart Rhythm Society/Asia Pacific Heart Rhythm Society/Latin American Heart Rhythm Society expert consensus statement on catheter and surgical ablation of atrial fibrillation

In the last three decades, ablation of atrial fibrillation (AF) has become an evidence-based safe and efficacious treatment for managing the most common cardiac arrhythmia. In 2007, the first joint expert consensus document was issued, guiding healthcare professionals involved in catheter or surgical AF ablation. Mounting research evidence and technological advances have resulted in a rapidly changing landscape in the field of catheter and surgical AF ablation, thus stressing the need for regularly updated versions of this partnership which were issued in 2012 and 2017. Seven years after the last consensus, an updated document was considered necessary to define a contemporary framework for selection and management of patients considered for or undergoing catheter or surgical AF ablation. This consensus is a joint effort from collaborating cardiac electrophysiology societies, namely the European Heart Rhythm Association, the Heart Rhythm Society, the Asia Pacific Heart Rhythm Society, and the Latin American Heart Rhythm Society .

Atrial septal pouches and ridges: Morphological features and potential implications in clinical practice

Incomplete or irregular fusion of the interatrial septum may result in several anatomic variants, including atrial septal pouches and ridges, whose knowledge and recognition are still poorly widespread in clinical practice. An educational review focused on the definition, clinical significance and diagnostic work-up of these anatomic findings was performed using PubMed, MEDLINE, Embase and Cochrane Central databases up to June 2023. Atrial septal pouches and ridges have been associated with an increased difficulty of catheter-based interventions requiring a transseptal approach, due to procedural challenges for transseptal puncture and the restricted motion of guidewires and catheters through the transseptal access. Additionally, left atrial septal pouch may serve as a thrombogenic nidus and a source of systemic embolism, mostly in the presence of factors leading to higher left atrial pressure and/or atrial blood stasis, which increase the risk of thrombus formation and embolic events, rather than for the only presence of left atrial septal pouch itself. Further investigations are needed in order to better elucidate the implications of such anatomic findings in daily clinical practice, and to provide the most appropriate decision-making strategies.

Design and Validation of a Soft Robotic Simulator for Transseptal Puncture Training

OBJECTIVE

Transseptal puncture (TP) is the technique used to access the left atrium of the heart from the right atrium during cardiac catheterization procedures. Through repetition, electrophysiologists and interventional cardiologists experienced in TP develop manual skills to navigate the transseptal catheter assembly to their target on the fossa ovalis (FO). Cardiology fellows and cardiologists that are new to TP currently train on patients to develop this skill, resulting in increased risk of complications. The goal of this work was to create low-risk training opportunities for new TP operators.

METHODS

We developed a Soft Active Transseptal Puncture Simulator (SATPS), designed to match the dynamics, static response, and visualization of the heart during TP. The SATPS includes three subsystems: (i) A soft robotic right atrium with pneumatic actuators mimics the dynamics of a beating heart. (ii) A fossa ovalis insert simulates cardiac tissue properties. (iii) A simulated intracardiac echocardiography environment provides live visual feedback. Subsystem performance was verified with benchtop tests. Face and content validity were evaluated by experienced clinicians.

RESULTS

Subsystems accurately represented atrial volume displacement, tenting and puncture force, and FO deformation. Passive and active actuation states were deemed suitable for simulating different cardiac conditions. Participants rated the SATPS as realistic and useful for training cardiology fellows in TP.

CONCLUSION

The SATPS can help improve catheterization skills of novice TP operators.

SIGNIFICANCE

The SATPS could provide novice TP operators the opportunity to improve their TP skills before operating on a patient for the first time, reducing the likelihood of complications.

The Role of Echocardiography in the Assessment of the Interatrial Septum and Patent Foramen Ovale as an Emboligenic Source

A comunicação do septo atrial (CIA) representa, aproximadamente, de 6%-10% dos defeitos cardíacos congênitos, com incidência de 1 em 1.500 nascidos vivos.1 Forame oval patente (FOP) é mais comum e está presente em mais de 20%-25% dos adultos.2 Síndromes clínicas associadas a CIA e FOP são variáveis, com implicações abrangendo a medicina pediátrica e adulta, neurologia e cirurgia.

O interesse adicional na anatomia do septo interatrial (SIA) aumentou substancialmente nas últimas duas décadas, com evolução simultânea dos procedimentos percutâneos envolvendo cardiopatia estrutural do lado esquerdo e procedimentos eletrofisiológicos. Idealmente, essas intervenções baseadas em cateter requerem rota direta para o átrio esquerdo (AE) através do SIA, necessitando completo entendimento de sua anatomia. Atualmente, tecnologias de imagem sofisticadas e não invasivas como ecocardiografia transesofágica bidimensional (ETE 2D) e tridimensional (ETE 3D), ressonância cardíaca (RMC) e tomografia computadorizada (TC) passaram por um extraordinário desenvolvimento tecnológico, fornecendo detalhes anatômicos das estruturas cardíacas visualizadas em formato 2D e 3D e são essenciais para diagnóstico e tratamento de pacientes com doenças cardíacas.

A avaliação da anatomia e anormalidades do SIA, portanto, requer abordagem padronizada e sistemática, integrando modalidades diagnósticas e fornecendo avaliação adequada e uniforme para terapias cirúrgicas e transcateter.

Three-dimensional transoesophageal echocardiography: how to use and when to use-a clinical consensus statement from the European Association of Cardiovascular Imaging of the European Society of Cardiology

Three-dimensional transoesophageal echocardiography (3D TOE) has been rapidly developed in the last 15 years. Currently, 3D TOE is particularly useful as an additional imaging modality for the cardiac echocardiographers in the echo-lab, for cardiac interventionalists as a tool to guide complex catheter-based procedures cardiac, for surgeons to plan surgical strategies, and for cardiac anaesthesiologists and/or cardiologists, to assess intra-operative results. The authors of this document believe that acquiring 3D data set should become a 'standard part' of the TOE examination. This document provides (i) a basic understanding of the physic of 3D TOE technology which enables the echocardiographer to obtain new skills necessary to acquire, manipulate, and interpret 3D data sets, (ii) a description of valvular pathologies, and (iii) a description of non-valvular pathologies in which 3D TOE has shown to be a diagnostic tool particularly valuable. This document has a new format: instead of figures randomly positioned through the text, it has been organized in tables which include figures. We believe that this arrangement makes easier the lecture by clinical cardiologists and practising echocardiographers.

Overview of the Interatrial Septum: Review of Cardiac Nomenclature for Transseptal Puncture

Transseptal puncture is an increasingly common procedure undertaken to gain access to the left side of the heart during structural heart disease interventions. Precision guidance during this procedure is paramount to ensure success and patient safety. As such, multimodality imaging, such as echocardiography, fluoroscopy, and fusion imaging, is routinely used to guide safe transseptal puncture. Despite the use of multimodal imaging, there is currently no uniform nomenclature of cardiac anatomy between the various imaging modes and proceduralists, and echocardiographers tend to use imaging modality-specific terminology when communicating among the various imaging modes. This variability in nomenclature among imaging modes stems from differing anatomic descriptions of cardiac anatomy. Given the required level of precision in performing transseptal puncture, a clearer understanding of the basis of cardiac anatomic nomenclature is required by both echocardiographers as well as proceduralists; enhanced understanding can help facilitate communication across specialties and possibly improve communication and safety. In this review, the authors highlight the variation in cardiac anatomy nomenclature among various imaging modes.

Correlation between percutaneous patent foramen ovale closure and recurrence of unexplained syncope

Background

The relationship between patent foramen ovale (PFO) and unexplained syncope remains to be illustrated. Therefore, this study aimed to explore the outcomes and prognostic factors for syncope recurrence after PFO closure.

Methods

Patients with both large right-to-left shunting (RLS) PFO and unexplained syncope who visited the cardiovascular department of Xiangya Hospital Central South University from 1 January 2017 to 31 December 2021 were consecutively enrolled in our study. The recurrence rate of syncope was compared between the non-closure group (n = 20) and the closure group (n = 91).

Results

A total of 111 patients were finally included. After 31.11 ± 14.30 months of follow-up, only 11% of patients in the closure group had recurrent syncope, which was much lower than that of the non-closure group (11.0 vs. 35%, P = 0.018). We further investigated the possible prognostic factors for syncope recurrence in the closure group and found syncope occurring more than five times preoperatively, hypertension, and residual RLS at 12-month follow-up were significantly correlated with a higher number of recurrences.

Conclusions

PFO closure reduced the recurrence rate of unexplained syncope. The efficacy of prevention was prognosticated by factors including the presence or absence of syncope induction, the frequency of syncope episodes, and the presence or absence of hypertension. Syncope recurrence was also related to residual shunts post closure.

Persistent left superior vena cava: An anatomical variation

The persistent left superior vena cava (LSVC) is a common anomaly of congenital heart disease. The presence of LSVC is commonly associated with other congenital cardiac anomalies such as atrial septal defect, tetralogy of fallot, aortic coarctation, ventricular septal defect and very rarely it occurs as an isolated finding. During a routine dissection for undergraduate students, a persistent LSVC along with variation in anterior cardiac vein and right septal pouch (RSP) was observed in heart of an approximately 48-year-old male cadaver. The persistent LSVC was draining into the right atrium via coronary sinus. The persistent LSVC is usually insignificant haemodynamically as commonly it drains into right atrium via coronary sinus, but incidental finding of LSVC is important to surgeons, interventional nephrologists and radiologists before placement of central venous access device. The insertion of central venous catheter via left internal jugular vein is difficult in presence of persistent LSVC. The right superior vena cava was normal. An anterior cardiac vein joined with the right marginal vein to form a common vein. The common vein opened into the right atrium. We also observed a RSP attached to the limbus fossa ovalis inferiorly which is a kangaroo pouch-like structure. A septal pouch is potential site predispose to thrombus formation and is more common on left side. In this case report we discuss embryology, clinical significance and review of literature related to persistent LSVC, anterior cardiac vein and SP.

Prevalence of left atrial septal pouch among patients with embolic stroke of undetermined source or stroke of known etiology: A retrospective study

Background and objectives

Cryptogenic strokes can be defined by the criteria established for an embolic stroke of undetermined source (ESUS). Some embolic events might be caused by a left atrial septal pouch (LASP), due to the potential of thrombus formation. In this study we aimed to determine if LASP is a risk factor for ESUS when compared to a population of strokes of known origin, the LASP screening rate in our institution and if LASP dimensions influences the risk of ESUS.

Methods

We retrospectively analyzed transesophageal echocardiograms (TEEs) in a large cohort of patients that had experienced ischemic strokes. Two authors performed blinded, independent searches for LASPs by reviewing 1152 TEEs from patients that had experienced a stroke or transient ischemic attack. We excluded 26 TEEs, due to incorrect imaging. Next, we reviewed patient medical files.

Results

Among the 1126 included patients, 148 had an ESUS (ESUS+ group) and 978 had strokes of known origin (ESUS– group). A LASP was present in 176 patients, including 32 patients (21.6% of LASPs) in the ESUS+ group and 144 patients (14.7% of LASPs) in the ESUS– group. In multivariate analysis, LASP was independently associated with ESUS (P = 0,019). 61.9% of LASPs that we found were not mentioned in reports from the original TEE operators.

Conclusion

This study demonstrated that LASPs were more prevalent in patients with ESUS than in patients with strokes of known origin. Our results gave rise to the question of whether anticoagulation would be appropriate for some patients with ESUS. New large-scale, prospective studies should be conducted to address this issue. Additionally, considering the low rate of LASP descriptions, we concluded that the awareness of operators should be raised to improve their success in identifying LASPs.

Prevalence of left atrial septal pouch among patients with embolic stroke of undetermined source or stroke of known etiology: A retrospective study

Background and objectives

Cryptogenic strokes can be defined by the criteria established for an embolic stroke of undetermined source (ESUS). Some embolic events might be caused by a left atrial septal pouch (LASP), due to the potential of thrombus formation. In this study we aimed to determine if LASP is a risk factor for ESUS when compared to a population of strokes of known origin, the LASP screening rate in our institution and if LASP dimensions influences the risk of ESUS.

Methods

We retrospectively analyzed transesophageal echocardiograms (TEEs) in a large cohort of patients that had experienced ischemic strokes. Two authors performed blinded, independent searches for LASPs by reviewing 1152 TEEs from patients that had experienced a stroke or transient ischemic attack. We excluded 26 TEEs, due to incorrect imaging. Next, we reviewed patient medical files.

Results

Among the 1126 included patients, 148 had an ESUS (ESUS+ group) and 978 had strokes of known origin (ESUS– group). A LASP was present in 176 patients, including 32 patients (21.6% of LASPs) in the ESUS+ group and 144 patients (14.7% of LASPs) in the ESUS– group. In multivariate analysis, LASP was independently associated with ESUS (P = 0,019). 61.9% of LASPs that we found were not mentioned in reports from the original TEE operators.

Conclusion

This study demonstrated that LASPs were more prevalent in patients with ESUS than in patients with strokes of known origin. Our results gave rise to the question of whether anticoagulation would be appropriate for some patients with ESUS. New large-scale, prospective studies should be conducted to address this issue. Additionally, considering the low rate of LASP descriptions, we concluded that the awareness of operators should be raised to improve their success in identifying LASPs.

Transseptal puncture: Review of anatomy, techniques, complications and challenges, a critical view

Transseptal puncture (TSP) was initially described to gain access to the left heart for hemodynamic assessment. Continuous evolution from its origins allows interventionists to perform a myriad of procedures that otherwise would be impossible to accomplish. In the recent years, the number of procedures in cardiology that require TSP has grown exponentially. Namely, transcatheter mitral valve repair and replacement, pulmonary vein isolation and left atrium appendage occlusion. In skilled hands, it is a safe and straightforward procedure; however, a lack of knowledge of the materials, anatomy of the interatrial septum and the technique can be met with life-threatening complications. Therefore, it is imperative that interventional cardiologists master this technique to successfully overcome these obstacles and ensure clinical outcomes in patients requiring TSP. The purpose of the following review is to critically analyze the available evidence regarding TSP, provide a step-by-step approach to the technique, the available materials and tips and tricks to overcome difficulties and manage complications.

Morphological Study of Fossa Ovalis in Formalin-Fixed Human Hearts and Its Clinical Importance

Background and Objectives: Our study aimed to investigate the gross anatomy aspects of the fossa ovalis (FO) and the presence of some anatomical variation resulting from the incomplete fusion of septum primum and septum secundum, such as an atrial septal pouch (SP) and left atrial septal ridge. Materials and Methods: Thirty-one adult human hearts removed from formalin-fixed specimens were examined to provide information about the morphology of the FO. The organs were free of any gross anatomically visible pathological conditions. Results: The most common variants were the FO located in the inferior part of the interatrial septum (64.51%), circular (61.3%), with a net-like structure (51.62%), prominent limbus (93.55%), and patent foramen ovale (PFO) (25.8%). The right SP was observed in 9.67% of specimens, the left SP was observed in 29.03% of cases, and in 51.61% of cases, a double SP was observed. One sample presented a right SP and a double left SP, and one case showed a triple left SP, which was not reported previously to our knowledge. Conclusions: Knowledge of the interatrial septal anatomy becomes important for interventional cardiologists and should be documented before transeptal puncture.

Transseptal puncture: procedural guidance, challenging situations and management of complications

A number of interventional procedures based on the transseptal puncture (TSP) have been developed in recent years. The increasing number of interventional procedures, as well as the use of large-bore sheaths and complex devices, has led to improvements in technique and equipment. The combined use of fluoro-scopy and of transoesophageal echocardiography (TEE) has increased safety and precision. However, TSP still represents a tricky procedure, which may become even more difficult in cases of challenging interatrial septa, and life-threatening complications may occur. Consequently, an in-depth knowledge of procedural steps, equipment, echocardiographic views, fossa ovalis anatomy and how to manage the most frequent complications is critical to performing a successful TSP.

Patent Foramen Ovale Channel Morphometric Characteristics Associated with Cryptogenic Stroke: The MorPFO Score

BACKGROUND

It is still disputable whether the specific morphologic properties of patent foramen ovale (PFO) may contribute to the occurrence of stroke. The aim of this study was to evaluate the differences in the morphometric and functional features of the PFO channel in patients with cryptogenic stroke and those without stroke.

METHODS

PFO channel morphology in 106 consecutive patients with cryptogenic stroke and 93 control patients without stroke with diagnosed PFO (by transesophageal echocardiography) was analyzed using transesophageal echocardiography. A validation cohort was established that consisted of 31 patients with cryptogenic stroke and 30 without stroke.

RESULTS

Multivariable regression logistic analyses indicated PFO channel length change (odds ratio [OR], 2.50; 95% confidence interval [CI], 1.75-3.55; P < .001), PFO length/height ratio during the Valsalva maneuver (OR, 0.75; 95% CI, 0.60-0.95; P = .015), septum primum thickness (OR, 0.34; 95% CI, 0.14-0.80; P = .013), septum secundum height (OR, 0.91; 95% CI, 0.84-0.98; P = .013), the presence of an atrial septal aneurysm (OR, 3.38; 95% CI, 1.27-8.97; P = .014), and large shunt (OR, 2.49; 95% CI, 1.13-5.46; P = .022) as PFO-related stroke factors. The Morphologic Stroke Factors of PFO (MorPFO) score was developed, in which six factors were included: PFO channel length reduction (≥21%; 7 points), short septum secundum (<8.6 mm; 5 points), thin septum primum (<1.6 mm; 3 points), large right-to-left shunt (3 points), low PFO channel length/height ratio during the Valsalva maneuver (≤2.1; 2 points), and atrial septal aneurysm presence (1 point). Patients with scores of 0 to 7 points have low-risk PFO channels, those with scores of 8 to 11 points have intermediate-risk PFO channels, and those with scores of 12 to 21 points have high-risk PFO channels. External validation showed good MorPFO score performance (C index = 0.90).

CONCLUSIONS

Transesophageal echocardiography can be used to differentiate pathogenic from incidental PFO channels on the basis of their morphologic characteristics. The MorPFO score may help identify high-stroke-risk PFO channels.

A modified percutaneous atrial balloon septoplasty for difficult transseptal puncture

Catheter ablation of atrial fibrillation sometimes encounters difficulty in passing the interatrial septum. This study reports a modified percutaneous atrial balloon septoplasty with short balloon to gain access to left atrium (LA) during challenging transseptal puncture (TSP).We retrospectively analyzed 20 patients (61.75 ± 7.31 years, 45% male) who received modified percutaneous atrial balloon septoplasty from August 2015 to October 2018. Soft-headed balance middle weight (BMW) guidewire was inserted into left superior pulmonary vein (LSPV) and short non-compliant balloon (15 mm in length and 4.0 or 5.0 mm in diameter) was used for atrial balloon septoplasty (ABS). Interatrial septum was located with inflated balloon and contrast "Hitting Wall" sign. All patients were followed-up for iatrogenic atrial septal defect (iASD) and other related complications.ABS and LA access were performed successfully without complications in all 20 patients. Time needed for ABS was correlated to the number of prior TSP (P = .007). During the 6-month follow-up, no remaining iASD was found by echocardiography.For atrial fibrillation patients with difficulty in passing the interatrial septum, this modified percutaneous ABS might be an alternative strategy which is safe to obtain transseptal access without short or long term complications.

Left atrial decompression as a palliative minimally invasive treatment for congestive heart failure caused by myxomatous mitral valve disease in dogs: 17 cases (2018-2019)

OBJECTIVE

To determine whether left atrial decompression (LAD) would reduce left atrial pressure (LAP) in dogs with advanced myxomatous mitral valve disease (MMVD) and left-sided congestive heart failure (CHF) and to describe the LAD procedure and hemodynamic alterations and complications.

ANIMALS

17 dogs with advanced MMVD and left-sided CHF that underwent LAD.

PROCEDURES

The medical record database was retrospectively reviewed for all LAD procedures attempted in dogs with MMVD and left-sided CHF between October 2018 and June 2019. Data were collected regarding signalment (age, breed, weight, and sex), clinical signs, treatment, physical examination findings, and diagnostic testing before and after LAD. Procedural data were also collected including approach, technique, hemodynamic data, complications, and outcome.

RESULTS

18 LAD procedures performed in 17 patients were identified. Dogs ranged in age from 7.5 to 16 years old (median, 11 years) and ranged in body weight from 2.9 to 11.6 kg (6.4 to 25.5 lb) with a median body weight of 7.0 kg (15.4 lb). Minimally invasive creation of an atrial septal defect for the purpose of LAD was successful in all dogs without any intraoperative deaths. Before LAD, mean LAP was elevated and ranged from 8 to 32 mm Hg with a median value of 14 mm Hg (reference value, < 10 mm Hg). Following LAD, there was a significant decrease in mean LAP (median decrease of 6 mm Hg [range, 1 to 15 mm Hg]). Survival time following LAD ranged from 0 to 478 days (median, 195 days).

CONCLUSIONS AND CLINICAL RELEVANCE

For dogs with advanced MMVD and left-sided CHF, LAD resulted in an immediate and substantial reduction in LAP.

Morphometric study of fossa ovale in human cadaveric hearts: embryological and clinical relevance

Atrial septal defect (ASD) is the 5th common congenital abnormality at birth. Secundum atrial defect and patent foramen ovale (PFO) are the most common atrial septal defects. In this setting, the anatomical functional characterization of the interatrial septum seems to be of paramount importance not only for device selection but also for therapeutic intervention. This study was carried out to evaluate the morphometric parameters of fossa ovale (FOv) in the human adult cadaveric hearts. For this study, 50 normal cadaveric human hearts available in the department of Anatomy over the period of 3 years were used where size, position, shape, nature of the FOv was noted. The size of the fossa was measured and prominence, location, and extent of the limbus fossa ovalis were observed. The probe patency of foramen ovale (FO) was confirmed. In most specimens, the fossa was oval (80%), the average transverse diameter was 24.21 mm, and the vertical diameter 26.84 mm. In 84% rim was raised. In 56% of cases, the fossa was present at the middle of the interatrial septum. The patency of foramen was observed in 3%. The findings of the present study provide pertinent information on the morphology of the FOv, which may be useful for device selection in treating ASDs and PFO. This would definitely help the clinicians in a deeper understanding of the region as very few cadaveric studies are available in the literature at present.

Newly-found channels in the interatrial septum of the heart by dissection, histologic evaluation, and three-dimensional microcomputed tomography

A minute thrombus can pass through a small type of interatrial communication, which can result in a stroke or transient ischemic attack and several associated symptoms. This study sought to investigate a new type of interatrial communication. Thirty-one hearts from embalmed adult cadavers were investigated. Each interatrial channels (IACs) was classified as either an open or obstructed channel according to the connection of each hole on the right and left surfaces of the interatrial septum. Open channels were found in two specimens (6.5%). Both open and obstructed IACs followed tortuous courses through the interatrial septum. On the right surface of the interatrial septum, the hole was usually found adjacent to the left border of the interatrial septum between the opening of the superior vena cava into the right atrium and the superior margin of the fossa ovalis. Conversely, holes on the left surface of the interatrial septum were usually found in the upper and middle parts adjacent to the left border of the interatrial septum. This novel finding is expected to support our understanding of the onset of possible symptoms such as stroke in the absence of classical atrial septal defects.

An Unusual Complication of Transseptal Puncture

The interatrial septum is a structure with complex embryological development. The true atrial septum is a circumscribed structure, and transgression outside of this area during transseptal puncture may result in entry into the extracardiac space or aorta that may result in a pericardial effusion or cardiac tamponade. (Level of Difficulty: Intermediate.).

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

OBJECTIVES

This 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.

BACKGROUND

Traditional 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.

METHODS

The 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.

RESULTS

A 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.

CONCLUSIONS

Electrographic 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.

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.

Presence of the annular ridge and location of the coronary sinus ostium as morphological features ofthe right atrium and interatrial septum in healthy common marmosets (Callithrix jacchus)

To effectively use a common marmoset (Callithrix jacchus) as an experimental animal species, it is critical to establish a normal characteristics and morphology of the organs of the common marmoset. Although gross morphology of the common marmoset heart is reportedly the same as that of humans, little information is available regarding detailed morphology of the right atrium and the interatrial septum. Heart specimens were collected from three male and 10 female marmosets aged 9 to 65 months to determine the morphological features of the right atrium and the interatrial septum. Ten specimens were evaluated morphologically with a stereoscopic microscope in accordance with preparation and investigation methods designed to facilitate evaluation. Three specimens were histologically evaluated after being stained with hematoxylin-eosin, Elastica van Gieson and periodic acid Schiff. An annular ridge that is not present in the human heart was present in the right atrium and the interatrial septum of the common marmoset hearts. Tissue structure of the annular ridge was similar to atrial myocardial fibers. Furthermore, location of the coronary sinus ostium was different to that in humans. Present findings were used to create a schematic view of the annular ridge in the common marmoset heart. In the common marmoset heart, the annular ridge may function as a valve of the superior vena cava ostium, inferior vena cava ostium, and coronary sinus ostium. Present study provides morphological evidence that common marmosets have a valve-like structure in the right atrium.

Fluoroscopic Anatomy of Right-Sided Heart Structures for Transcatheter Interventions

Performing transcatheter tricuspid valve interventions requires a thorough knowledge of right-heart imaging. Integration of chamber views across the spectrum of imaging modalities (i.e., multislice computed tomography, fluoroscopy, and echocardiography) can facilitate transcatheter interventions on the right heart. Optimal fluoroscopic viewing angles for guiding interventional procedures can be obtained using pre-procedural multislice computed tomography scans. The present paper describes fluoroscopic viewing angles necessary to appreciate right-heart chamber anatomy and their relationship to echocardiography using multislice computed tomography.

Topographic characteristics of the left atrial medial isthmus

BACKGROUND

The purpose of this study was to provide detailed topography of the left atrial medial isthmus (situated between the right inferior pulmonary vein ostium and the medial part of the mitral annulus).

METHODS

Two hundred human hearts (Caucasian, 22.5% females, 48.7 ± 4.9 years old) were investigated.

RESULTS

The mean length of the medial isthmus was 42.4 ± 8.6 mm. Additionally, the medial isthmus line was divided by the oval fossa into three sections with equal mean lengths (upper: 14.2 ± 7.2 vs middle: 14.1 ± 6.1 vs lower: 14.9 ± 4.6 mm; P > .05). The left upper section of the atrial wall was thinner than the lower section (2.5 ± 1.1 vs 3.4 ± 1.6 mm; P < .0001). This study noted three separate spatial arrangements of the isthmus line. Type I (54.5%) had an oval fossa located outside the isthmus line; type II (32.5%) had an oval fossa crossed by the isthmus line, and type III (13.0%) had an oval fossa rim located tangentially to the isthmus line. In 68.5% of the examined specimens, the isthmus area had a smooth surface. Conversely, the remaining 31.5% had additional structures within its borders such as diverticula, recesses, and tissue bridges.

CONCLUSION

This study is the first to describe the morphometric and topographical features of the left atrial medial isthmus. Interventions within the medial isthmus line should be performed cautiously, especially when they are transected by the oval fossa (32.5%). Careful navigation of the area is also recommended due to the possibility of existent additional structures. The latter could lead to catheter entrapment during ablation procedures.

Acute Procedural Complications of Cryoballoon Ablation: A Comprehensive Review

Catheter ablation is increasingly performed for treatment of atrial fibrillation (AF). Balloon based procedures have been developed aiming at safer, easier and more effective treatment as compared to point to point ablation. In the present review article, we aimed to discuss acute procedural complications of cryoballoon ablation.

Distances between transseptal puncture site and anatomical landmarks

The aim of the study was to provide quantitative data and to look for new landmarks useful during transseptal puncture (TSP) using a fluoroscopy-guided approach. METHODS AND RESULTS: A total of 104 patients at mean age 57 ± 12 years, of whom 92% underwent pulmonary vein isolation, were analysed. Before TSP catheters were placed in the coronary sinus (CS) and His bundle region. A guidewire running from femoral vein through great veins was left loose in superior vena cava. Before TSP X-ray images were taken in right anterior oblique (RAO) 45° and RAO 53° projections. Locations posterior to TSP site in RAO were described with negative values and those anterior with positive values. The measured distances in millimeters were as follows: (a) between TSP site and posterior atrial wall (RAO 45 = -21 ± 7 mm; RAO 53 = -19 ± 6 mm (b) between TSP site and free guidewire (RAO 45 = -5 ± 4 mm, RAO 53 = -3 ± 4 mm (c) between TSP site and CS ostium (RAO 45 = 9 ± 6 mm; RAO 53 = 8 ± 5 mm (d) between TSP site and His region (RAO 45 = 29 ± 8 mm; RAO 53 = 30 ± 8 mm). We observed correlations between measured distances and age, body mass index and sizes of cardiac chambers. The distance between TSP site and the line projected by the guidewire running between great veins, measured in mid-RAO projections, was very small. CONCLUSION: The distances between TSP site and standard anatomical landmarks used during TSP vary with regard to age, physique and cardiac chamber dimensions. TSP site, as assessed in mid RAO, is in direct vicinity to the line projected by a guidewire running between the great veins.

Flap valve of the heart foramen ovale revisited: macroscopic and histologic observations of human near-term fetuses

We assessed the flap valve of the foramen ovale (FO valve) by examining 30 hearts from human fetuses of gestational age 30-40 weeks. We dissected the hearts, examined their macroscopic morphology, and then prepared semiserial sagittal sections across the valve. Although the primary septum is expected to extend along the left atrial face, eight hearts had a superior rim of the fossa ovalis on the left atrial face that was too thick and high, so there was no smooth continuation with the valve. Moreover, three of these eight hearts each had a flap valve that was fused with a long and narrow plate arising from the caval orifice. Histological analysis indicated that 21 specimens each had a candidate primary septum that contained myocardium, although the left sinuatrial valve (LSAV) contained fibrous tissue, but little or no myocardium. In each of 17 hearts, a candidate primary septum was attached to the left atrial face of the fossa, and parts of the LSAV extended to and approached the right atrial face. However, seven of these 17 hearts each had a folded small primary septum. Another four of these 17 hearts each had an LSAV that extended widely to the fossa, and a candidate primary septum (which might be a remnant) attached to the left atrial side of the LSAV. These variations suggest that the LSAV makes a major contribution to the FO valve in some fetal hearts. Consequently, the fetal FO valve appears to have heterogeneous morphology and origin.

Revisiting Anatomy of the Interatrial Septum and its Adjoining Atrioventricular Junction Using Noninvasive Imaging Techniques

Interest in the anatomy of the interatrial septum (IAS) and its adjoining atrioventricular (AV) junction has risen enormously in the past two decades with the simultaneous evolution of left-sided percutaneous structural heart disease and complex electrophysiologic procedures. These procedures require, in fact, a direct route to the left atrium through the IAS. Thus, a thorough understanding of the complex anatomy of the IAS and AV junction is essential for performing a safe and effective transseptal puncture. There is a large amount of literature carefully describing the anatomy of the IAS and AV junction. These studies are based almost exclusively on anatomic specimens. Conversely, in this review the authors emphasize the role of noninvasive imaging techniques, in particular cardiac magnetic resonance, two- and three-dimensional transesophageal echocardiography, and computed tomography in visualizing specific aspects of the normal IAS and AV junction. Where appropriate, the authors present images side by side, with corresponding anatomic specimens.

Morphological variations of the interatrial septum in ovine heart

Smooth septum interatrial septum, patent foramen ovale (PFO) channel and atrial septal pouches (SPs) are commonly described variants in humans. Recent discoveries on the clinical significance of left-sided SP may encourage the creation of new strategies and devices for the management of SPs. However, these strategies may first be tested in the ovine model before implementation in humans. Unfortunately, little is known about the presence of SPs in ovine. In this study a total of 60 ovine (Ovis aries) hearts were examined. The interatrial septum morphology was assessed and the PFO channel and SPs were measured. The most commonly occurring variant were PFO channels (25.0%) with channel lengths of 5.4±2.3 mm. Smooth septums were observed in 18.3% of hearts. In the remaining cases, septums had a left septal ridge (15.0%), left SP (11.7%), left septal bridge (10.0%), right SP (10.0%), or had both a right SP and left septal ridge (10.0%). No double SPs were observed. The mean right SP depth was 3.4 ± 1.2 mm, and its mean ostium width and height were 7.9±1.8 mm and 2.8±1.0, respectively. For the left SP, the mean depth was 6.0±1.7mm, the ostium width was 7.9±2.4mm, and the ostium height was 4.1±1.6mm (range: 2.3-6.4mm). In conclusion the interatrial septum of ovine hearts exhibit morphologies that are more similar to humans than they are to swine, which should be taken into account during experimental studies. The presence of a left SP in sheep hearts make ovine models a promising alternative to the human heart for developing left-sided SP management devices and techniques.

Porcine heart interatrial septum anatomy

BACKGROUND

The left-sided atrial septal pouch (SP), a recently re-discovered anatomical structure within the human interatrial septum, has emerged as a possible source of thrombi formation and a trigger for atrial fibrillation, thereby potentially increasing the risk for ischemic stroke. In many studies, the swine interatrial septum has been used as model of the human heart. Also, possible new strategies and devices for management of the SPs may first be tested in this pig model. Therefore, in this study, we aimed to evaluate swine interatrial septum morphology and to compare it with the human analog, especially in the light of SP occurrence.

METHODS

A total of 75 swine (Sus scrofa f. domestica) hearts were examined. The interatrial septum morphology was assessed, and SPs were measured.

RESULTS

The most common variant of the interatrial septum was smooth septum (26.6%) followed by the patent foramen ovale channel and right SP (both 22.7%). No left or double SPs were observed. In 28.0% of all cases the fold of tissue (left septal ridge) was observed on the left side of the interatrial septum in the location where the left-sided SP should be expected. The mean length of the patent foramen ovale channel was 7.1±1.5mm. The mean right SP depth was 6.3±2.2mm, and its ostium width and height were 5.8±1.2 and 5.3±1.6mm, respectively.

CONCLUSIONS

There are significant differences between human and porcine interatrial septum morphology that should be taken into account during experimental studies. The absence of the left SP in swine results in the inability to use porcine heart as an experimental model for left-sided SP management.

Recognizing and reacting to complications of trans-septal puncture

INTRODUCTION

The transseptal puncture (TSP) enables access to the left heart, through the fossa ovalis (FO), both in electrophysiology and in cardiac interventional procedures. TSP is usually safe in experienced hands. Sometimes TSP can be technically demanding and carries the risk of severe complications in approximately 1%. While performing a TSP, every effort should be taken in order to avoid complications. In the event of complications, prompt recognition and reaction are essential and a combined 'heart-team' management may be the most effective approach. Areas covered: Main TSP-related complications are cardiac tamponade, aortic root puncture, embolic stroke, transient ST elevation of inferior leads and iatrogenic atrial septal defect. A challenging TSP may be expected in presence of difficult IAS-FO anatomies, previous TSP, IAS occluder device and previous IAS surgical repair. Use of echo imaging and special needles (ie., radiofrequency needle and J-shaped guidewire) may avoid TSP-related complications in difficult settings. Expert commentary: Some tools are available to help minimize the risks of TSP. However, their availability might be limited. To increase safety of TSP, an adequate training of physicians, identification of patients in whom it might be difficult and a prompt recognition of complications seem to be the most important background.

Predicting the Dimensions of an Intracardiac Partial-Assist Pump for Percutaneous Delivery by Analytical and Numerical Methods

A minimally invasive ventricular assist device is under development for percutaneous insertion into the left atrium via transseptal access from the right atrium (RA). This study aimed to mathematically describe the vascular anatomy along possible insertion pathways to determine the device's maximum outer dimensions. We developed 2-dimensional mathematical models describing the vascular anatomy to the RA from three access points: subclavian vein (SCV), internal jugular vein (IJV), and femoral vein (FV). All pathways terminated by turning from the superior or inferior vena cava (SVC/IVC) into the RA. The model equations were based on restriction points in the pathways and were solved using anatomic size values 1 SD below published mean values so that the device will accommodate most patients. Vessels were considered rigid so that vessel deformation (and therefore risk) is minimized during device insertion. Maximum device length was calculated for a range of device diameters. The length at the most constraining angle in each turn was the maximum allowable device length. The least restrictive pathway was from the right FV, the turn from the IVC through the atrial septum being the most restrictive point. For a 10-mm diameter device, the length restriction for this pathway was 45 mm, whereas those for the right IJV and SCV were 42 and 21 mm, respectively. Medical device developers can apply these models to determine size specifications of new devices, whereas interventional physicians can apply them to determine if an existing device is appropriate for an individual patient.

Persistent left superior vena cava

Persistent left superior vena cava (PLSVC) is the most common congenital malformation of thoracic venous return and is present in 0.3 to 0.5% of individuals in the general population. This heart specimen was dissected from a 35-year-old male cadaver whose cause of death was determined as non-cardiac. The heart was examined and we found a PLSVC draining into the coronary sinus. The right superior vena cava was present with a small-diameter ostium. An anomalous pulmonary vein pattern was observed; there was a common trunk to the left superior and left inferior pulmonary veins (diameter 17.8 mm) and an additional middle right pulmonary vein (diameter 2.7 mm) with two classic right pulmonary veins. The PLSVC draining into the coronary sinus had led to its enlargement, which could have altered the cardiac haemodynamics by significantly reducing the size of the left atrium and impeding its outflow via the mitral valve.

A practical guide for building a highway between atria during transseptal puncture without radiation

OBJECTIVE

To investigate whether switching the ablation catheter between the right and left atria through transseptal puncture site can be accurately performed without fluoroscopy.

METHODS

Forty patients with persistent atrial fibrillation (mean age, 60.2±7.4 years; 65% males) got "2C3L" approach were randomized in a 1:1 ratio to undergo either crossing interatrial septum guided by fluoroscopy (trackless group) or crossing septum guided by track image that was mapped by Carto3 system (track group).

RESULTS

The three-dimensional image of the track could be mapped smoothly and shown clearly. No significant differences were found in the success rates between the two groups (100% vs. 100%, p>0.05). However, the procedure of crossing septum was completed without any fluoroscopy use in track group, which showed a shorter procedure time than trackless group (4±3 s vs. 20±10 s, p<0.01).

CONCLUSION

Visualizing the track passing through the puncture site using Carto3 system can guide the ablation catheter in safely crossing the intra-atrial septum quickly with zero fluoroscopy.

Transseptal puncture - Review of anatomy, techniques, complications and challenges

In recent years, the transseptal puncture approach has enabled passage of increasingly large and complex devices into the left atrium. Traditional tools remain effective in creating and dilating the initial puncture, with an acceptable safety profile. Even for skilled operators, the procedure is technically demanding and requires sound understanding of atrial anatomy. Intracardiac echocardiography is useful in cases of previous septal repair, poorly defined fossa ovalis anatomy or when considering patent foramen ovale portal crossing. Iatrogenic atrial septal defect (iASD) is the most commonly encountered long-term complication and there is increasing evidence that larger devices are leading to symptomatic defects. The size of the sheath crossing the septum is the strongest predictor of iASD formation but other factors such as longer procedure times, significant catheter manipulation and high pulmonary pressures also contribute. Transcatheter mitral valve repair involves the use of large 22 Fr catheters which carry alarmingly high rates of defect persistence with precipitation of symptoms and possible influence on mortality. Long-term follow up data, particularly beyond the 12-month period are lacking and resultantly, evidence to guide management is sparse. Refinements of conventional instruments, as well as innovations to puncture the septum without mechanical pressure, herald a progressively safer future for the transseptal technique.