Role of imaging in interventions on structural heart disease

Abstract

Recent technological progresses have led to the development of new devices and procedures which have greatly improved the chance to effectively treat structural heart diseases in both children and adults. Interventional cardiology has been receiving fast and wide implementation as an effective alternative treatment to surgery for several congenital and acquired diseases. The advent of transcatheter valve implantation/repair techniques constitutes one of the main breakthroughs of the last decades. Such development and implementation is strictly related to a continuous progress in cardiac imaging as well. Indeed, multimodality cardiac imaging (such as X-ray, echocardiography, MRI, multidetector computed tomography) has become essential in providing accurate patient selection and in monitoring the interventional procedures in order to optimize the success rate and minimize the frequency of complications. The current article aims at reviewing the role of multimodality imaging for planning and guiding interventions in several structural heart diseases.

Keywords::

• interventional cardiology
• multimodality cardiac imaging
• non-invasive imaging techniques
• patient selection
• percutaneous treatment
• procedural guidance
• structural heart disease

Acknowledgements

Expert Review of Cardiovascular Therapy was granted permission to use figures by Abbott Vascular (IL, USA), who holds full rights.

Financial & competing interests disclosure

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending or royalties.

No writing assistance was utilized in the production of this manuscript.

Key issues

• • Transthoracic echocardiography (TTE) is the most widely used imaging tool for evaluation of size and hemodynamic significance of atrial septal defects (ASDs) and for decision-making.

• • Transesophageal echocardiography (TEE), coupled with fluoroscopy, is a fundamental imaging modality for guidance of percutaneous closure of ASD in terms of real-time information about rims defect, device deployment and release, final results.

• • Real-time three-dimensional transesophageal echocardiography (RT3DTEE) allows three-dimensional imaging in real time without the need for multiple-beat acquisition and is particularly useful for guidance of percutaneous procedures especially when multiple devices are used.

• • Intracardiac echocardiography (ICE) technique overcomes the need for intubation and general anesthesia but is only feasible in adults and older children. It provides monoplane bidimensional imaging and has the advantage, compared with TEE, of better imaging of the postero-inferior portion of the atrial septum.

• • TTE, done with a saline bubble test, can be useful in diagnosing a clinically relevant intracardiac shunt through a patent foramen ovale (PFO), at rest and after Valsalva maneuver.

• • The contrast-enhanced transcranial Doppler ultrasonography does not help imaging the PFO, but is much sensitive in detecting a right-to-left shunt if more than 10 air micro-bubble spikes in the middle cerebral artery are detected.

• • TEE, performed routinely in the diagnostic evaluation of a PFO, provides multiple information about the anatomical features. Coupled with a bubble test, it's useful to detect the presence and direction of interatrial shunt.

• • Inlet, doubly committed and malalignment-type ventricular septal defects (VSDs) classically cannot be approached percutaneously.

• • Pre-procedural TTE evaluation is mandatory to assess the size, number, location of the VSD and to rule out VSD-related aortic valve dysfunction.

• • Percutaneous VSD closure is routinely performed under fluoroscopy and two-dimensional transesophageal echocardiography (2DTEE) guidance.

• • 3DTEE displays an en face view of the VSD from both ventricles, providing additional information in terms of shape, dimensions and relationships. It often yields accurate guidance for positioning of the delivery system and deployment of the occluder device.

• • Recently pre-procedural assessment of post-infarction defects by cardiac magnetic resonance (CMR) has been suggested, potentially providing detailed anatomic imaging of size, location and tissue margins.

• • Pre-procedural TEE is mandatory to assess the clinical significance of a paravalvular leak (PVL) and the likelihood of percutaneous closure.

• • Most mitral paravalvular defects are crescentic or oblong and often have serpiginous tracks, rather than being cylindrical holes.

• • The 3DTEE is particularly useful in analyzing PVLs and guiding the percutaneous closure by using orthogonal views.

• • Posterior aortic PVL are usually best seen by TEE, while anterior PVL are usually best imaged by TTE or ICE with the probe located in the right ventricular outflow tract (RVOT).

• • One major problem is the estimation of leak regurgitation severity due to presence of ‘garden-hose’ effect or shadowing.

• • Conventional catheter angiography is considered the gold standard for assessing the morphology and hemodynamics in patients with aortic coarctation (AoCoA).

• • CMR, with 3D reconstruction, has become the preferred non-invasive diagnostic tool for both initial evaluation and late surveillance after surgical or interventional AoCoA treatment.

• • Important issues to address are restenosis and/or aneurysm formation after AoCoA treatment.

• • One of the CMR major limitations is to achieve good quality pictures after stent implantation, due to the presence of signal dropout artifact. In this regard, computed tomography (CT) is the most suitable non-invasive modality for a good assessment during follow-up, being able to discover stent fractures as well.

• • The most common problem for adults and children following repair of complex congenital heart disease is dysfunction of the RVOT and pulmonary valve.

• • CMR has been shown to be accurate in the evaluation of a wide range of right ventricular (RV) structural and functional parameters, pulmonary artery anatomy and geometry.

• • Normalized RV end-diastolic volume is one of the most important preoperative measures of RV dimensions and function.

• • CMR with 3D RVOT and pulmonary arteries reconstruction is crucial in pre-procedural assessment for percutaneous pulmonary valve implantation, as certain anatomic criteria are to be met for the safe anchoring of the percutaneous valve.

• • Conventional angiography and CT scan play a key role in the selection of the vascular access before transcatheter aortic valve implantation (TAVI).

• • TAVI procedure exclusively relies on imaging to select the device; in this regard, aortic annulus measure is crucial.

• • Conventional TTE and TEE are largely used in clinical practice, although the majority of investigators relies on multi-slice computed tomography (MSCT) for measuring the annulus diameters (minimum, maximum and medium), the perimeter and the height of coronary ostia.

• • It may be valuable to consider data from both TEE and MSCT, and mainly in the presence of evident inter-test incongruity, to cautiously review both. This ‘multimodality’ evaluation may reduce the chance for error.

• • TEE and MSCT are crucial to define anatomy of left atrial appendage (LAA) that may be multilobated and very variable in size.

• • 2D + 3DTEE, along with fluoroscopy, are pivotal to guide LAA percutaneous closure.

• • Currently, the sole method to perform a percutaneous repair of a regurgitant mitral valve consists of the Mitraclip System that is clearly inspired by the ‘edge-to-edge’ surgical technique.

• • A complete TEE evaluation is necessary for a detailed assessment of the mitral valve anatomy in order to evaluate the feasibility of the percutaneous procedure.

• • Important parameters to achieve are: coaptation length, coaptation depth, presence of one or more prolapsing scallops and their extent/severity, height and width of the flail.

• • Color Doppler should identify the origin of the regurgitant jet that must be between A2 and P2 scallops.

• • TEE is pivotal during every phase of the procedure: transseptal puncture, clip positioning and acute result evaluation while the clip is still not released.

• • The 3D X-plane view can be helpful to simultaneously visualized perpendicular planes.

• • 3D ‘surgical view’ provides a clear image of the mitral anatomy and the open arms of the clip in order to achieve a correct grasping of the leaflets.

Notes