P1333 The importance of multimodality imaging in the characterization of a congenital myocardial diverticulum
Authors: Ramirez-Escudero Ugalde G , Arantza Manzanal Rey A M R , Nora Garcia Ibarrondo N G I , Mireia Codina Prat M C P , Lara Ruiz Gomez L R G , Maria Castellanos Alcalde M C A , Amaia Lambarri Izaguirre A L I , Koldo Ugedo Alzaga K U A , Roberto Candina Urizar R C U , Cristina Asla Ormaza C A O 
Published: January 2020

Abstract
Congenital ventricular diverticulum is a rare cardiac malformation, usually detected on echocardiographic examinations in asymptomatic patients. However, they can also cause embolisms, arrhythmias and sudden death due to ventricular rupture. Multimodality imaging can help in the characterization of its morphology and in the differential diagnosis.
We report a case of an 83-year-old woman, pacemaker carrier due to complete atrioventricular block, who consulted for paroxysmal episodes of palpitations, being diagnosed of atrial fibrillation. A transthoracic echocardiogram was performed, observing an appendix at basal septal level with contractility of its wall and with doppler-colour inside, suggestive of myocardial diverticulum. Echocardiographic contrast was injected for better delimitation and characterization of the cavity. MRI was after performed for better characterization of this structure, confirming the presence of an accessory chamber with muscular wall and normal contractility at the level of the basal interventricular septum, without pathological enhancements. We reviewed an angioCT performed for other reasons some years ago, confirming the presence of the same structure, which went unnoticed in that study. The patient followed controls and remained asymptomatic, without evolutionary echocardiographic changes, so that a conservative attitude was maintained.
Congenital ventricular diverticulum is formed by an appendix of the entire left ventricular (LV) wall. It can be differentiated into two types: muscular (more frequent, not prone to rupture and associated with other congenital malformations) or fibrous (frequently localized at the base of the heart or in subvalvular areas).
Differential diagnosis may include true LV aneurysms (abnormal LV contour with systolic dyskinesia and involving thinned fibrous tissue) and LV pseudoaneurysms (acute contained rupture of the ventricle wall, often after myocardial infarction, also akinetic or dyskinetic).
Congenital cardiac diverticulum is characterized by a rapid contrast filling and a narrow neck. MRI provide tissue characterization and is an important tool that helps in the differential diagnosis. In cardiac diverticulums, a thinned but contractile wall is present, without pathological delayed enhancements. In true aneurysms, the wall shows delayed enhancement (scar tissue). Pseudoaneurysms are only composed by pericardium, and the border of the aneurysms show enhancement indicating peri-aneurysmal infarcted area. Left ventricular catheterization can also be useful assessing the morphology and dynamics of the left ventricular chamber.
In small, muscular and asymptomatic diverticulums, conservative treatment with follow-up is often recommended. When symptoms appear, medical or surgical treatment should be proposed.
Abstract P1333 Figure. Congenital myocardial diverticulum