Aneurysm of the pars membranacea

Right Ventricular Outflow Tract Obstruction by an Aneurysm of the Ventricular Membranous Septum: A Systematic Review of Case Reports

“…During an autopsy in 1826, Laënnec 36 was the first to report an aneurysm of the ventricular membranous septum (quoted from Thurnam's paper 37 ). Massig 38 described a patient in whom a part of the aneurysmal sac was formed by the septal leaflet of the tricuspid valve (quoted from Hamby's paper 39 ). Chesler et al 14 reported a similar pathological finding.…”

“…However, it may be impossible to distinguish a tricuspid pouch from a true membranous septal aneurysm angiographically. 39 Anderson et al 41 reported the mechanisms of closure as follows: reduplication of the tricuspid valve (N = 16), adhesion of tricuspid valve leaflets (N = 6), and subaortic tissue tags (N = 2), which might have originated from the remnant of the membranous septum. Meanwhile, Kaplan et al reported that the perioperative exploration revealed a perforated true aneurysmal sac in 7 of 12 patients.…”

Electro-Anatomical Approach to Membranous Septal Aneurysm: Potential as a Focus of Critical Ventricular Arrhythmias

“…Aneurysm of the membranous portion, which was first described in 1826, is a congenital structure protruding into the right ventricle and can be associated with various pathologies such as rupture, obstruction in the right ventricle and arrhythmias [1]. Ventricular tachycardia (VT) and complete atrioventricular block (AVB) were presented as complications of membranous septal aneurysm (MSA) in old reports [2] and still described as crucial problems in current literatures [3,4], however, only few studies performed electrophysiological investigation for MSA in its long history. To address the underlying mechanisms of such arrhythmias, both anatomical and electrophysiological approaches are indispensable, however, they have not been implemented due to the rarity and difficulty to approach.…”