Primary Noncompaction of the Ventricular Myocardium from the Morphogenetic Standpoint

Abstract

This review compiles the current knowledge of normal and abnormal myocardial morphogenesis to facilitate an unambiguous diagnosis of primary myocardial noncompaction. During the early stages of development, the formation of trabeculae with the resulting increase in myocardial surface is a adaptation of the rapidly growing heart to improve nourishment by exchange diffusion from the cardiac lumen. Once the coronary vasculature has developed, the switch to cardiac nutrient supply through active circulation from the subepicardial space is paralleled by gradual compaction of the myocardial trabeculae. This results in a decrease of the inner, trabeculated myocardial layer with a parallel increase in thickness of the outer, compact myocardial layer. Similar to the direction of coronary arterial development, this process proceeds from the epicardium toward the endocardium and from the base of the heart to the apex. Based on developmental data, congenital myocardial noncompaction represents a failure of normal embryonic myocardial maturation. The time of arrest of this process will determine the extension of myocardial noncompaction within the ventricle. Whereas disturbances of myocardial microcirculation are frequent in these hearts, direct communications between the myocardial cavity and the coronary arteries (sinusoids) do not belong to this morphogenetic entity.

Left ventricular non‐compaction: Prevalence in congenital heart disease

“…Alternatively, hemodynamic alterations during fetal life may be a cofactor for the development of ventricular non-compaction in a patient with genetic predisposition. 24,25 The purpose of this study was to explore the association between congenital heart defects and LVNC and to report its prevalence within adults with a distinct type of congenital cardiac defect.…”

Estimation of Prevalence of the Left Ventricular Noncompaction Among Adults

“…This is deemed a distinct form of cardiomyopathy whose pathophysiology can mimic either a hypertrophic or a dilated cardiomyopathy. Its etiology is unknown and however, is associated with many ill-defined genetic abnormalities, besides familial clustering and isolated cases are reported in otherwise healthy children and young adults (1)(2)(3)(4)(5). LVNC is a phenotypic diagnosis based on a set of criteria by the transthoracic echocardiography (1, 3, 5 -20).…”

Left ventricular hypertrabeculation/noncompaction in gylcogenosis type 1b

“…Usually, LVHT is restricted to the apex and the lateral wall. Only rarely are the interventricular septum or the basal segments affected [3].…”