Interventional Cardiology The Expanding Role of Echocardiography in Interventional Cardiology
Lindsay A Smith, Amit Bhan and Mark J Monaghan Department of Non-Invasive Cardiology, King’s College Hospital, London
Abstract
Echocardiography provides excellent realtime imaging of the heart, making it the imaging modality of choice immediately before, during and after cardiac interventional procedures. It helps to guide case selection and execution of the intervention, evaluates the effects of the intervention and enables early detection of complications. Advances in the design and technology of medical devices and delivery systems, coupled with demand for alternative non-surgical therapies for common medical problems, have led to an increase in the volume, variety and complexity of non-coronary cardiac interventional procedures performed. Many of these procedures require a multidisciplinary team approach and demand optimal imaging to ensure successful outcomes. The aim of this article is to review the expanding role of echocardiography in non-coronary interventional cardiology in adults.
Keywords
Echocardiography, cardiac ultrasound, transoesophageal echocardiography, intra-cardiac echocardiography, 3D echocardiography, valvular heart disease, congenital heart disease, atrial septal defect, patent foramen ovale, balloon mitral valvuloplasty, mitral valve repair, aortic stenosis, transseptal catheterisation, pericardiocentesis, myocardial biopsy, alcohol septal ablation, left atrial appendage occlusion
Disclosure: Lindsay A Smith has no conflicts of interest to declare. Amit Bhan has received honoraria from Philips. Mark J Monaghan has received research support and honoraria from GE, Philips, Siemens and TomTec. Received: 26 April 2010 Accepted: 24 May 2010 Citation: European Cardiology, 2010;6(2):71–6 Correspondence: Mark J Monaghan, Department of Non-Invasive Cardiology, King’s College Hospital, Denmark Hill, London, SE5 9RS, UK. E:
mark.monaghan@
nhs.net
The field of non-coronary cardiac intervention is undergoing rapid expansion, driven by advances in technology and increasing demand for alternative, non-surgical therapies for common structural heart diseases. As a result, the volume, variety and complexity of percutaneous catheter-based procedures being performed in cardiac catheterisation laboratories are increasing. Traditionally, fluoroscopy has been used to guide such procedures, but it has important limitations, such as significant radiation exposure, a 2D perspective and limited tissue differentiation, as well as the requirement for radiographic contrast use. The greater complexity of these newer procedures, particularly those involving heart valve intervention, necessitates more sophisticated and exacting imaging techniques, both to facilitate appropriate case selection and to provide procedural guidance, thus increasing the likelihood of successful outcome. Contemporary advances in echocardiography imaging techniques ensure these modalities are well suited to the imaging requirements of this exciting and expanding field of interventional cardiology.
Realtime 3D imaging, made possible by the development of a full matrix transducer capable of acquiring pyramidal-shaped ultrasound data sets, has been a major advance in transthoracic echocardiography (TTE). Furthermore, transducers and systems capable of single-beat 3D acquisitions, thus eradicating stitching artefacts, are now available. Miniaturisation of this 3D technology has enabled coupling with a transoesophageal echocardiography (TEE) probe providing high-quality 3D TEE images. Data acquisition with 3D TEE can be performed in three different modes: narrow-
© TOUCH BRIEFINGS 2010
angle acquisition, displaying realtime images; 3D zoom mode, generating a realtime truncated pyramidal data set; and wide-angle full-volume mode, enabling a larger pyramidal data set but requiring electrocardiographic gating and acquisition over one to seven cardiac cycles. The wide-angle full-volume mode is currently the only mode to support colour Doppler imaging. Unlike the cumbersome 3D predecessors, current data sets can be readily manipulated either online or offline to display cardiac structures or to enable quantitative analysis.
Intra-cardiac echocardiography (ICE) is a recent application of ultrasound technology that offers imaging of comparable or even superior quality to TEE. Early ICE acquired cross-sectional images using a rotating transducer similar to intra-vascular ultrasound (rotational ICE). The incorporation of miniaturised phased-array technology into an intra-cardiac catheter has now enabled sector- based imaging (phased-array ICE). Rotational ICE provides good near- field but more limited far-field imaging. However, phased-array ICE has deeper penetration and better far-field imaging than rotational ICE, in addition to being steerable and allowing Doppler imaging.
The ideal echocardiography modality would provide high-quality, realtime 3D imaging in a format easily comprehended by the interventional cardiologist, with minimal interference to the flow of the interventional procedure being performed. It would be safe, minimally invasive and widely available at low cost. Currently, no one echocardiography imaging modality fulfils all these criteria. Each has
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