Teaching Case

A 65-year-old male without any comorbidities suffered an embolic neurological stroke 4 months back. 2D Echocardiography performed at the time of the event revealed a cystic mass over the mitral valve, no patent foramen ovale identified. Blood cultures were negative, leucocyte counts were normal, C-Reactive protein level was normal.  Carotid and lower limb venous doppler showed no significant disease. There was no history of prior cardiac imaging or interventions. Thus the cardiac mass was the presumed aetiology for the embolic stroke. He was managed conservatively with dual antiplatelet therapy and is currently referred for MR evaluation of cardiac mass.

A 2.0 x 2.0 cm sized well defined cystic lesion with a thin imperceptible wall is noted at the left ventricular (LV) aspect of the anterior mitral leaflet along the chordae tendinae of the anterolateral papillary muscle. It moves with the mitral leaflet. Moderate mitral regurgitation is seen. No dynamic left ventricular outflow tract obstruction is seen. (Figure 1, Figure2, Video1 and Video2)

On dynamic post-contrast images, the centre of the cystic lesion shows contrast enhancement matching the blood pool in all phases. The centre shows late gadolinium enhancement (LGE) whereas the cyst wall is non-enhancing. (Figure 3, Video 3)

Introduction [1]

Intracardiac blood cysts are congenital malformations seen commonly in infants below 2 months of age and regress spontaneously in the first 6 months. Presentation in adults is rare. These are located in the endocardium of semilunar or atrioventricular valves and their supporting structures and can be seen in any cardiac chamber.

Symptoms [1,2]

Intracardiac blood cysts have variable clinical outcomes. Most of them are asymptomatic and are detected incidentally. Left ventricular outflow obstruction, valvular dysfunction/non-coaptation or cyst rupture may cause other rare presentations to include dyspnoea, chest pain, syncope, embolic stroke or transient ischemic attack.  

Aetiology [1,3]

Multiple hypotheses have been proposed to explain the development of blood cysts

• Abnormal development of cardiac mesothelial progenitor cells
• Hematoma formation in subvalvular apparatus.
• Trapping of blood in crevices during valve development  
• Valvular blood vessel ectasia
• Acquired cysts after a cardiac catheterization, valvular surgeries & blunt trauma

Imaging [1-6]

Echocardiography is an excellent screening tool and the usual first-line investigation for the detection of blood cysts. Typical ultrasound features include well defined, thin-walled, anechoic cystic lesions which can move along with the cardiac cycle. Contrast echocardiography can be used to accurately assess the nature, attachment and perfusion. 

On computed tomography, they can appear as well defined non-enhancing hypodense lesions within cardiac chambers.

Cardiac magnetic resonance imaging is useful to assess tissue characteristics. They appear hyperintense on T2WI, isointense on turbo spin echo, and/or with prolonged T1 relaxation time in inversion recovery sequences. Early or late gadolinium enhancement is uncommon. In some cases, it may enhance depending upon the size of vascular channels that permit the passage of blood and contrast to and fro into the cyst.

Management [2-4]

Treatment is controversial. Surgical excision is preferred for symptomatic cysts, valvular dysfunction or obstruction is seen on imaging. Minor asymptomatic cysts without hemodynamic significance should be followed up with serial imaging for potential risk of embolism and development of valvular dysfunction  

Take home message

Presentation of intracardiac blood cyst in an adult is rare. These are usually discovered incidentally. It must be considered as a differential for cystic cardiac masses. The most widely accepted approach to management is the surgical excision of symptomatic blood cysts and monitoring of minor asymptomatic cysts with serial imaging.

Written informed patient consent for publication has been obtained.