Ventricular septal crypt in hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is characterized by diverse patterns of left ventricular (LV) hypertrophy. Recently, unusual structural convolutions of the LV wall have been reported, including non-compaction in the distal chamber, and ‘clefts’, ‘crypts’, and ‘crevices’ in portions of the LV free wall. With cardiovascular magnetic resonance (CMR), we have recently identified a striking and unusual configuration of the basal ventricular septum that does not resemble in appearance or location any of the aforementioned patterns. Notably, this particularly deep crypt in the septum differs considerably in appearance from the relatively shallow indentations reported in the posterior (inferior) free wall of HCM gene carriers without LV hypertrophy (suggested as premonitory to the appearance of wall thickening). The clinical significance of this novel morphology, identified only by CMR, is uncertain at this time, although its clinical relevance may emerge as investigators image increasing numbers of HCM patients with CMR. (Panel A) CMR horizontal long-axis diastolic cross-sectional image from a 25-year-old asymptomatic woman with non-obstructive HCM and maximal LV thickness situated in anterior free wall (23 mm). The particularly deep myocardial crypt in the basal ventricular septum (VS) penetrates the myocardium to a depth of 12 mm leaving only 2 mm of residual septal wall (arrow). Wall thickness in the adjacent area of septum is 15 mm. (Panel B) CMR short-axis image with a linear blood containing area in the posterior (inferior) portion of VS (arrows) identifies the location of the crypt in this plane. (Panel C) Post-contrast image showing delayed enhancement that is confined to anterior free wall (arrows). (Panel D) Post-contrast short-axis image corresponding to Panel B showed no evidence of delayed enhancement. LV, left ventricle; RV, right ventricle; VS, ventricular septum. This patient had a normal global ejection fraction (75%), absence of regional wall motion abnormalities, and mild systolic anterior motion of the mitral valve without obstruction to LV outflow; coronary arteries were normally positioned at their origins from the aorta. The myocardial crypt was not visualized in standard echocardiographic cross-sectional planes. ECG showed narrow deep Q-waves in II, III, AVF, V3–V6, and delayed progression of precordial R-waves, with diminished or absent R-wave in V1–V3, a not uncommon pattern in HCM. Commercial genetic testing was negative for nine sarcomere genes known to be disease-causing for HCM, as well as LAMP2, PRKAG2, and Fabry disease, a result that occurs in ∼50% of patients with clinically diagnosed HCM. This work was supported in part by a grant from The Hearst Foundations, New York, NY.