A double-chambered left ventricle with a giant thrombus: a case report.

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A double-chambered left ventricle (DCLV) is an extremely rare congenital disease that is often asymptomatic and undiagnosed until adulthood. The incidence of a double-chambered right ventricle is estimated to be 1 in 36000 patients, while the incidence of DCLV is certainly even lower. To date, only a handful of cases of DCLV have been reported. A 4-year-old boy was admitted to the local hospital in 2019 due to chest discomfort. He had mild tachypnoea and wheezing. Upon physical examination, his heart was found to be enlarged without any obvious cardiac murmur. Cardiac percussion also revealed an enlargement of the heart, and further echocardiography confirmed a diagnosis of a 'dual-chamber left ventricle'. No other cardiac or systemic abnormalities were observed. In January 2022, the patient came to our hospital for further diagnosis and treatment. The laboratory results including coagulation testing showed no obvious abnormality. The 24-hour Holter monitor revealed a sinus rhythm with a left bundle branch block (I°). The bedside chest X-ray indicated an abnormal protrusion of the left margin of the heart. Transthoracic echocardiography showed that the left ventricle was divided into main and accessory chambers by a thick muscle bundle in the middle of the left ventricular cavity. Cardiac magnetic resonance (CMR) imaging confirmed this, and additionally found a giant thrombus in the accessory cavity. A DCLV is an extremely rare congenital heart disease that is often asymptomatic and undiagnosed until adulthood. The aetiology of DCLV is still unclear; however, some reports have suggested that it may be related to a hypoplasia of the regional myocardial intra-trabecular sinusoids or an intra-myocardial aneurysm during the embryonic period. Additionally, some cases have indicated that DCLV may be a subtype of genetic cardiomyopathies. A DCLV is characterized by a subdivision of the left ventricle into two chambers by an abnormal septum or by muscle bands. This case report introduces a patient with DCLV and a giant thrombus, in which CMR imaging plays an important role in both diagnosis and differential diagnosis.