Crypts, Diverticula, and Left Ventricular Noncompaction

Abstract

Left ventricular noncompaction (LVNC), crypts, and diverticula are rare myocardial phenotypes that could be identified in different settings not always representing a pathological condition. Crypts (clefts, fissures, or crevices) are narrow invaginations within the myocardium, composed of normal myocardial fibers, with systolic obliteration. Congenital diverticula (muscular diverticula) are outpouchings extending beyond the myocardial border (key difference with crypts), containing all the three ventricular layers (endocardium, myocardium, and epicardium) and showing synchronous systolic contraction. Crypts and diverticula should be differentiated from aneurysms (large thin-walled akinetic or dyskinetic outpouchings composed of fibrotic myocardium, usually connected to LV cavity through a wide neck, being either congenital or acquired) and pseudoaneurysms (large thin-walled akinetic or dyskinetic outpouchings derived from myocardial wall rupture, composed only of the epicardial layer, usually connected to LV cavity through a narrow neck).

Cardiac MRI is pivotal in the diagnosis of these abnormalities, thanks to the better image quality when compared to echocardiography and to its capability to assess the presence of late gadolinium enhancement whose identification is associated with worse prognosis. In this chapter, anatomical definition will be provided together with a clinical overview, in order to enable the reader to recognize and manage these rare conditions. Moreover, a descriptive and self-explicative image series of clinical cases is included to support and better convey to the readers the anatomical features of the three conditions together with clinical setting in which they have been encountered.