The role and indications for imaging in patients with cardiovascular disease is dependent on the clinical characteristics, presentation, and overall patient conditions. Professional societies have developed numerous guidelines,
1,
2,
3,
4,
5 appropriateness use criteria, decision pathways for management,
6,
7 and other standards documents that help the clinician approach patients according to their existing or suspected pathology and decide when—and which—imaging modality may be warranted.
The overall goals and roles of cardiac imaging in the patient with structural heart disease are listed in
Table 39.1. A roadmap to the imaging needs and goals for the currently approved transcatheter procedures can be found in
Table 39.2 (transcatheter aortic valve replacement [
TAVR]),
Table 39.3, (mitral valve repair with MitraClip©) and
Table 39.4 (implantation of left atrial appendage occluder devices). Examples of images obtained during preprocedural planning and intraprocedural imaging are displayed in
Figures 39.1, 39.2, 39.3 and 39.4.
Preprocedural Imaging
Transthoracic echocardiogram (
TTE) is usually the initial imaging modality to evaluate patients with valvular disease or other suspected structural heart diseases, because it is widely available, noninvasive, and has almost no contraindications. A complete
TTE allows for a comprehensive evaluation of cardiac chamber size and function, including visualization of valves and identification of most cardiac pathologies. The use of Doppler imaging (color and spectral) in addition to two- and three-dimensional (2D and 3D)
TTE is critical to evaluate hemodynamic abnormalities such as intracardiac shunts, valvular stenosis, and valvular regurgitation. On certain occasions,
TTE can be improved by using related techniques such as agitated saline injection (for detection of right-to-left shunts), ultrasound enhancing agents (for better delineation of the endocardium, intracardiac thrombus or masses, and myocardial perfusion imaging for alcohol septal ablation), or myocardial strain imaging (for left ventricular [LV] function).
Once a pathology is identified, a thorough evaluation must include quantifying severity, size, morphology, and mechanisms underlying the pathology, as well as the
consequences of the pathology to other structures within the heart (ie, ventricular or atrial remodeling, pulmonary hypertension, etc).
Although
TTE frequently provides most of the information needed, the cardiac imager must understand the limitations of this modality and utilize alternative imaging modalities (ie, transesophageal echo [
TEE], cardiac computed tomography [CT], cardiac magnetic resonance imaging [
CMR]) when some of the needed information cannot be addressed with confidence by
TTE. Although the severity of valvular disease or shunts is best assessed with
TTE, detailed anatomy and morphology is best evaluated with
TEE or CT. Furthermore, 3D imaging provides anatomic information that cannot be obtained from 2D imaging and allows for more accurate measurements of structures in all their dimensions, including perimeter, volume, area, and circumference, which is critical for the selection of the appropriate-sized devices. For the most part, 3D imaging for structural procedures can be obtained through
TEE, multislice cardiac CT, or
CMR.
TEE offers better spatial resolution than
TTE (structures are better seen except those in the apex of the LV) with a similarly high temporal resolution; however, it is more invasive and requires moderate sedation.
TEE‘s main contraindication is known or suspected obstructive disease of the upper gastrointestinal tract (ie, oropharyngeal, esophageal, or gastric).
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