Yet Again: Accessary Left Ventricle Mistaken for Ventricular Septal Defect.

Abstract

Description of Clinical Presentation: A 37-year-old female presented a diagnostic challenge to the outpatient echocardiography laboratory when she was noted to have a possible large ventricular septal defect (VSD) on the background of previously reported spontaneously closed peri membranous VSD as a child. She had recent acute hospitalisation with shortness of breath and random chest pains and only past medical history of controlled asthma. Physical examination was unremarkable apart from a murmur. She had normal routine blood tests, inflammatory markers, and NT- pro-BNP. 12 lead ECG revealed incomplete RBBB. D Dimer slightly but Lung VQ scan excluded pulmonary emboli. Diagnostic Techniques and Their Most Important Findings: Initial 2D/3D transthoracic echocardiography (TTE) showed an abnormal contractile chamber around the right heart connected to the left ventricle through the wide defect with bidirectional flow located proximal to aortic valve at left ventricular outflow tract (LVOT) level (Fig 1). Cardiac magnetic resonance imaging (CMRI) confirmed the TTE findings of a small muscular contractile chamber with similar wall thickness and trabeculation as of the left main ventricle and no communication with the right ventricle. No intracardiac shunt identified on the phase contrast measurement of flow through the great arteries (Qp: Qs = 1.0) (Fig 2). Prospective gated computed tomography cardiac angiogram (CTCA) confirmed the findings of the TTE and CMRI, excluding premature coronary artery disease but revealing abnormal coronary anatomy. There was left coronary dominance with left main stem trifurcating into an LAD, LCX and a separate coronary artery to this abnormal contractile chamber. Also, a large calibre RV branch seen arising from the LAD running along anterolateral surface of the right ventricle supplying the territory normally supplied by the right coronary artery. RCA itself was a very recessive vessel. All the above scans confirmed this rare incidental congenital cardiac condition as being an accessary left ventricle than a true VSD (Fig 3). Associated dynamic LVOT obstruction was ruled out with a semi supine exercise bike stress echocardiogram with no associated exercise induced dysrhythmias or myocardial ischaemia. Patient reassured and clinic follow up arranged. Learning Points from this Case: Although rare2, appearance of ALV on routine bedside imaging can lead to diagnostic challenges. The differentials include an LV pseudoaneurysm, double chambered right ventricle (DCRV), LV diverticulum, persistent VSD, and accessary left ventricle. An LV pseudoaneurysm was considered unlikely because of the synchronous contraction of the structure with rest of the ventricle3. LV diverticulum was ruled out due to wide connection with the main LV4. Absence of the advanced cyanotic heart disease signs led to accurate diagnosis of ALV rather than large VSD. From our experience, systematic clinical and multi-modality imaging approach nicely illustrated in confirming the final diagnosis. [Formula presented] [Formula presented] [Formula presented] Author Disclosure: S Roghani: Nothing to disclose; M Shahid: N/A; I Cox: N/A; J Lee: N/ACopyright � 2024