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

Optimal Localization of the Foramen Ovale for Transseptal Puncture Using the Vertebral Body Units

Background and Objectives: Although transesophageal or intracardiac echocardiography and radiofrequency needles are employed to guide transseptal puncture, their routine utilization is associated with substantial expense. No reports have analyzed the use of the foramen ovale position to effectively guide transseptal punctures on chest X-rays or computed tomography scout views, which are more cost-effective approaches to safely and effectively guide the procedure. We aimed to find the foramen ovale position on chest computed tomography scout views to effectively guide percutaneous transseptal punctures. Materials and Methods: The study population included 31 patients treated with extracorporeal membrane oxygenation (ECMO) for cardiogenic shock, 32 patients diagnosed with atrial fibrillation (AF) who underwent MDCT, and 197 patients who underwent MDCT for non-cardiac conditions. Vertebral body units, defined as the distance between two adjacent vertebral bodies (the sixth and seventh thoracic spines) inclusive of the intervertebral disk space, were used to express the distance from the carina to the foramen ovale on computed tomography scout views. Results: The mean vertebral body units, distance from the carina to the foramen ovale (carina-foramen ovale), and distance from the carina to the foramen ovale on chest computed tomography scout views (carina-foramen ovale vertebral body units-1) were 2.3 ± 0.2 cm, 6.9 ± 0.9 cm, and 3.0 ± 0.3, respectively. Multivariate analysis showed significant correlations between the carina-foramen ovale vertebral body units-1 and sex (β = 0.080; p = 0.028), body mass index (β = -0.020; p < 0.001), age (β = 0; p = 0.013), and the application of extracorporeal membrane oxygenation or the presence of atrial fibrillation (β = 0.130; p = 0.004). Conclusions: Although a three-dimensional approach was not employed, the foramen ovale position may serve as a radiologic guide in various clinical settings where transseptal punctures are required. This technique may be an effective aid in transseptal puncture procedures.

Twenty-five years of research in cardiac imaging in electrophysiology procedures for atrial and ventricular arrhythmias

Catheter ablation is nowadays considered the treatment of choice for numerous cardiac arrhythmias in different clinical scenarios. Fluoroscopy has traditionally been the primary imaging modality for catheter ablation, providing real-time visualization of catheter navigation. However, its limitations, such as inadequate soft tissue visualization and exposure to ionizing radiation, have prompted the integration of alternative imaging modalities. Over the years, advancements in imaging techniques have played a pivotal role in enhancing the safety, efficacy, and efficiency of catheter ablation procedures. This manuscript aims to explore the utility of imaging, including electroanatomical mapping, cardiac computed tomography, echocardiography, cardiac magnetic resonance, and nuclear cardiology exams, in helping electrophysiology procedures. These techniques enable accurate anatomical guidance, identification of critical structures and substrates, and real-time monitoring of complications, ultimately enhancing procedural safety and success rates. Incorporating advanced imaging technologies into routine clinical practice has the potential to further improve clinical outcomes of catheter ablation procedures and pave the way for more personalized and precise ablation therapies in the future.

Characterization of the interatrial septum by high-field cardiac MRI: a comparison with multi-slice computed tomography

Background

Assessment of the interatrial septum (IAS) has become an attractive area of interest for a variety of important interventional procedures. Newer imaging modalities like multi-slice computed tomography (MSCT) and cardiac MRI (CMR) can provide higher resolution and wider field of view than echocardiography. Moreover, high-field (3-Tesla) CMR can even enhance spatial and temporal resolution.

The characteristics of the interatrial septum were retrospectively studied in 371 consecutive subjects (201 men, 31–73 years old) in whom MSCT was performed primarily for non-invasive evaluation of the coronary arteries. All subjects underwent both MSCT and MRI scans within 0–30 day’s interval. A 3D volume covering the whole heart was acquired across the heart with and without contrast enhancement. Also, patients underwent cardiac MSCT examinations using 64-row MSCT scanners.

Results

The mean scan time of MSCT was 10.4 ± 2.8 s and 9.7 ± 2.9 min for CMR. The mean length of IAS by CMR and CT was 39.65 ± 4.6 mm and 39.28 ± 4.7 mm, respectively. The mean maximal thickness of IAS by CMR and CT was 3.1 ± 0.97 mm and 3.15 ± 0.95 mm, respectively. The mean thickness of fossa ovalis by CMR and CT was 1.04 ± 0.36 mm and 1.04 ± 0.44 mm, respectively. The mean length of fossa ovalis by CMR and CT was 12.8 ± 3.7 mm and 12.8 ± 3.5 mm, respectively. Finally, the mean angle of IAS by CMR and CT was identical (155 ± 9.2°). Measurements of various morphological features of IAS showed no statistically significant difference between CMR and CT, with an excellent correlation and close relationship regarding IAS length, maximal IAS thickness, fossa ovalis thickness, fossa ovalis length, and IAS angle (r = 0.98, 0.98, 0.95, 0.96, and 0.92, respectively).

Conclusion

Whole-heart 3D acquisition at 3-T MRI using a free-breathing technique provides a valuable non-invasive imaging tool for excellent assessment of the interatrial septum—as compared to MSCT—that may have significant clinical implication for diagnostic purposes and therapeutic interventional procedures, as it may facilitate planning, improve outcome, and shorten its duration.

Automated segmentation of the atrial region and fossa ovalis towards computer-aided planning of inter-atrial wall interventions

BACKGROUND AND OBJECTIVE

Image-fusion strategies have been applied to improve inter-atrial septal (IAS) wall minimally-invasive interventions. Hereto, several landmarks are initially identified on richly-detailed datasets throughout the planning stage and then combined with intra-operative images, enhancing the relevant structures and easing the procedure. Nevertheless, such planning is still performed manually, which is time-consuming and not necessarily reproducible, hampering its regular application. In this article, we present a novel automatic strategy to segment the atrial region (left/right atrium and aortic tract) and the fossa ovalis (FO).

METHODS

The method starts by initializing multiple 3D contours based on an atlas-based approach with global transforms only and refining them to the desired anatomy using a competitive segmentation strategy. The obtained contours are then applied to estimate the FO by evaluating both IAS wall thickness and the expected FO spatial location.

RESULTS

The proposed method was evaluated in 41 computed tomography datasets, by comparing the atrial region segmentation and FO estimation results against manually delineated contours. The automatic segmentation method presented a performance similar to the state-of-the-art techniques and a high feasibility, failing only in the segmentation of one aortic tract and of one right atrium. The FO estimation method presented an acceptable result in all the patients with a performance comparable to the inter-observer variability. Moreover, it was faster and fully user-interaction free.

CONCLUSIONS

Hence, the proposed method proved to be feasible to automatically segment the anatomical models for the planning of IAS wall interventions, making it exceptionally attractive for use in the clinical practice.

Atrial Fibrillation Ablation: Do We Really Need Preprocedural Imaging?

Atrial fibrillation is the most common human arrhythmia, causing significant mortality and morbidity. Because of the potential for complications, it is important that procedures be made as safe and effective as possible by combining safe procedural planning with effective therapy delivery. To change the current approach, large randomized studies are needed to guide the selection of patients who may safely undergo ablation without transesophageal echocardiography to exclude thrombus. For institutions routinely using computed tomography and magnetic resonance imaging to assess pulmonary vein anatomy before procedures, the possibility of excluding intracardiac thrombi using these imaging modalities should be considered.

Imaging in catheter ablation for atrial fibrillation: enhancing the clinician's view

Catheter ablation is an effective treatment for symptomatic atrial fibrillation. A thorough understanding of the left atrium anatomy and its adjacent structures is critical for the success of the procedure and for avoiding complications. Pre-procedural imaging aims at determining left atrial size, anatomy, and function and is also used to rule out an atrial thrombus. During the procedure, while fluoroscopy remains the gold standard imaging modality for guiding transseptal catheterization and catheter ablation, numerous other imaging modalities have been developed to improve 3D navigation and ablation. Finally, post-operative imaging intends to monitor heart function and to search for potential complications like pulmonary vein stenosis or the rare but dramatic atrio-oesophageal fistula. This review discusses the relative merits of all imaging modalities available in the context of catheter ablation of atrial fibrillation.