Fluoroscopic “heart chamber” anatomy – the case for imaging modality-independent terminology
Interventional cardiologists have traditionally relied upon fluoro scopic imaging for percutaneous coronary interventions. Transcatheter structural heart interventions, however, require additional imaging modalities such as echocardiography and multislice computed tomography (MSCT) for pre-, intra- and post-proce-dural assistance. Unlike cardiac surgeons who have direct visuali-sation of structures during valve repair or replacement, physicians performing transcatheter heart valve interventions are entirely dependent on multimodal cardiac imaging for valve size selection and positioning; imaging becomes the “eyes of the Heart Team”.
MSCT has emerged as the critical imaging modality for patient and device selection prior to transcatheter structural heart interventions. MSCT is unique as it provides a complete 3-dimensional (3D) dataset of the heart and vasculature that is amenable to multiplanar reconstruction for 2-dimensional (2D) or volume-rendered interpretations. Herein, we present a modality-independent terminology for understanding volumetric images in the context of transcatheter heart valve therapies. The goal of this system is to allow physicians to readily interpret the orientation of fluoroscopic, MSCT, echocardiographic and MRI images, thus generalising their understanding of cardiac anatomy to all imaging modalities.
X-ray fluoroscopy provides excellent resolution and tracking of cardiac devices, but is limited by the requirement for contrast enhancement to visualise anatomical structures. Understanding fluoroscopic cardiac anatomy can, however, facilitate optimal positioning and deployment of prostheses during transcatheter valve repair/replacement, left atrial appendage occlusion, sep-tal defect closure, paravalvular leak closure, etc.
To date, these therapies have been performed using standardised fluoroscopic viewing angulations that do not account for the considerable variation in anatomy between patients. Two-dimensional fluoroscopy creates foreshortening and overlap of discrete cardiac structures and consequently the use of suboptimal fluoroscopic projections can yield suboptimal procedural outcomes.
Nicolo Piazza, Darren Mylotte and Pascal Theriault Lauzier