Myocardial densification insufficiency, also known as left ventricular densification insufficiency, left ventricular high trabeculation, or spongy myocardium. Normal densification of the lax reticular structures of the ventricular myocardium occurs in the first trimester of pregnancy in normal fetuses and causes the disease if the densification process stops in utero. The disease has been reported in children and adults of various ages. Echocardiographic features are segmental hypertrophy of the left ventricular wall containing 2 layers: a thin dense dirty layer and an extremely thickened non-dense endocardium, the latter with prominent trabecular structures with deep depressions. The apical and mid-ventricular segments of the inferior and lateral walls are most frequently involved. The disease involves the left ventricle and may be associated with right ventricular involvement, resulting in ventricular diastolic and systolic insufficiency and clinical signs of heart failure. It is often not associated with congenital cardiac malformations, but a pathologic face may be present. 1/4 of cases have a familial history. The most common complication is heart failure, followed by thromboembolism, ventricular arrhythmias and the W-P-W anticipatory syndrome. Even with proper treatment, the disease will continue to progress. Treatment is mainly anti-heart failure, such as digitalis, diuretics, ACEI, but also includes oral anticoagulants, ICD implantation and heart transplantation.