A rare giant atrial septal cardiac blood cyst in an adult: a case report

Abstract

Introduction

Cardiac blood cysts are exceedingly rare cardiac tumours, typically found on cardiac valves during infancy.¹ We discuss the diagnosis and management of a unique case of a giant atrial septal cardiac blood cyst in an adult.

Summary figure

Case presentation

A 59-year-old Chinese lady with history of hypertension, hyperlipidemia, and transient ischaemic attack was admitted for intermittent, non-exertional, central chest discomfort of 3 days duration. There were no associated symptoms of shortness of breath, palpitations or lower limb swelling. She had no fever. She was a non-smoker and had no other cardiovascular risk factors.

Physical examination revealed a blood pressure of 125/85 mmHg, heart rate of 110/min, respiratory rate of 16/min and an oxygen saturation of 99% on room air. Cardiovascular examination revealed an elevated jugular venous pressure with a pan-systolic murmur best heard over the left lower sternal edge. Lungs were clear on auscultation. She had no pedal oedema.

Full blood count, renal, liver, thyroid, and coagulation panels were normal. Cardiac troponins were not significantly elevated. NT-proBNP was 105 pg/mL (≤99 pg/mL).

Chest radiography (Figure 1A) depicted clear lung fields, mild cardiomegaly, and an uptilted cardiac apex. Electrocardiogram (Figure 1B) showed sinus tachycardia, extreme axis deviation, p pulmonale, and features of right ventricular strain.

Figure 1

(A) Chest radiograph depicting mild cardiomegaly and an uptilted cardiac apex. (B) Electrocardiogram showing features of right ventricular strain.

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In view of the above presentation, transthoracic echocardiogram (TTE) was performed.

Her TTE (Figure 2 and Supplementary material online, Video S1) showed a large relatively echo-lucent intracardiac mass with some internal calcification, measuring 5.8 × 4.6 cm. It was attached to the interatrial septum and prolapsed into the right ventricle (RV) during each cardiac cycle. Right heart chambers were dilated. RV systolic function was normal. The tricuspid annulus was dilated with incomplete coaptation of the tricuspid valve leaflets with moderate tricuspid regurgitation. There was no significant tricuspid stenosis. Left ventricular (LV) systolic function was normal with no regional wall motion abnormalities. There was anterior mitral leaflet prolapse (A2 scallop) with moderate mitral regurgitation. Pulmonary artery systolic pressure was 33 mmHg.

Figure 2

Transthoracic echocardiogram showing the large ovoid right atrial (RA) mass (denoted with white arrows) attached to the interatrial septum and prolapsing into the right ventricle (RV). (A) Short axis view in systole, (B) Short axis view in diastole depicting the RA mass. (C) Tricuspid inflow view. (D) Tricuspid inflow view with colour Doppler showing moderate tricuspid regurgitation. (E) Apical RV focused view showing the RA mass prolapsing into the RV. (F) Subcostal view showing the attachment of the RA mass to the interatrial septum. (G) Tricuspid Doppler depicting tricuspid valve gradients.

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With a diagnosis of intracardiac mass, as per ESC guidelines,² we proceeded with further non-invasive assessment with a computerized tomography (CT) of the thorax, abdomen, pelvis, and CT pulmonary angiogram concurrently.

Her CT scan (Figure 3) showed a smoothly marginated hypodense homogenous mass measuring 6.3 × 5.0 × 4.7 cm attached by a stalk to the interatrial septum. There was no evidence of infiltration of surrounding tissues, metastasis or pulmonary embolism. As imaging information was adequate, transesophageal echocardiogram (TEE) was not performed. Further characterization of the mass with cardiac magnetic resonance imaging (MRI) would’ve been technically challenging as the mass was highly mobile and hence was not performed.

Figure 3

Computed tomography imaging showing a large pedunculated hypodense smooth marginated right atrial mass (6.3 × 5.0 × 4.7 cm) arising from the interatrial septum.

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As she was symptomatic from the intracardiac mass and it was hemodynamically significant on imaging, heart team consensus was to proceed with surgical resection. Pre-operative coronary angiogram showed minor coronary artery disease (30% stenosis in mid-left anterior descending artery).

She underwent open heart surgery and intra-operatively, a 6 × 5 cm pedunculated right atrial tumour was noted to be attached to the interatrial septum. The right atrial tumour was excised at the base of its stalk, dissecting deep into the muscular layer to remove the entire tumour. Interatrial septum was intact. The epicardial defect was then closed primarily. As moderate to severe tricuspid regurgitation was noted on intra-operative TEE during rewarming, tricuspid annuloplasty was performed with minimal residual tricuspid regurgitation. No intervention was performed for her moderate mitral regurgitation as the mitral annulus was not dilated. Post-operative TTE showed normal LV size and function, normal RV size with impaired RV systolic function, moderate mitral regurgitation, and no tricuspid regurgitation.

The patient was discharged well after an uncomplicated post-operative recovery. She remained well during a follow-up visit at two weeks, and her chest pain had resolved. She has been well at 4 months post-surgery. A follow-up TTE is planned in a year for surveillance of mitral regurgitation.

Histologic evaluation showed a blue-grey cystic mass measuring 6 × 5.5 × 4 cm with a stalk measuring 1 × 1 × 1 cm. It had a glistening external surface (Figure 4A). Cut sections revealed a cystic space containing altered blood (Figure 4B). The wall of the lesion was thin (0.1 cm) with no solid areas; focal calcification was noted within the wall. Microscopically, the lining of the lesion consisted of benign-appearing endothelium. These findings were in keeping with a cardiac blood cyst.

Figure 4

Cardiac blood cyst. (A) Gross Specimen. (B) Cut Sections.

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Discussion

Primary cardiac tumours have an incidence of 0.001%³ with over 90% of them benign (predominantly myxomas in adults, rhabdomyomas in children).² First described by Elsasser⁴ in 1844, cardiac blood cysts are extremely rare benign cardiac tumours very rarely seen in adults. They usually are found in newborns and infants and generally disappear during growth.¹ To date, less than 100 cases have been reported in adults.⁵ They normally involve the cardiac valves and commonly measure 1–3 cm in size.⁶ The most common valve involved is the mitral valve⁶ though blood cysts on other valves have been reported.^7,8 Blood cysts attached to the interatrial septum are extremely rare.^6,9 While often solitary, multiple blood cysts on both leaflets of the mitral valve has been previously reported.¹⁰

Pathogenesis of the cardiac blood cyst remains unclear to this day with multiple theories and no consensus. Earlier theories suggested that blood cysts occurred due to changes in valve cusp vasculature.¹¹ It is however now known that the heart valves are largely avascular structures making the above unlikely. Dow and Harper support the view of Haushalter and Thiry that blood cysts originate from blood in the heart cavity which has been pressed into a valve cusp. They postulate that during the embryonic stage, traction of the chordae tendineae make a furrow in the meshed fibrous structure of the valve cusps and fusion of the edges of the furrow lead to cardiac blood cyst development.¹² These theories as well as the echocardiographic findings would indicate a chronic process, despite the patients’ clinical presentation.

Though benign, they have been associated with outflow tract obstruction,¹³ valvular regurgitation,¹³ and embolization¹⁴ (myocardial infarction/stroke). Symptomatic patients do well with surgical resection⁶ while long-term outcomes in asymptomatic patients followed up with serial TTEs are mixed with cyst enlargement,⁸ cyst rupture¹⁵ and embolic events¹⁴ reported. Due to its rarity, existing literature is limited to case reports and small case series and prior to the ESC guidelines,² there was a lack of guidelines on management.⁶

Echocardiography is the most commonly used imaging modality for identification and characterization of intracardiac masses.² Our patient’s TTE had some classical atrial myxoma features—polypoid mass attached to the interatrial septum through a stalk moving to-and-fro into the cavity, sometimes prolapsing into the ventricular cavity across the atrioventricular valve, she also fit the typical patient profile. Another possible differential was a cardiac cyst due to internal echo-lucency. Clinically, there was no suspicion of infective endocarditis and there were no imaging features to suggest abscess or infiltration of surrounding structures. Due to lack of internal septations and lack of deformation during the cardiac cycle, hydatid cyst was less likely. TEE has superior resolution in highlighting the relationship of intracardiac masses to surrounding structures and can help differentiate tumours from infective complications like abscesses. It is superior to cardiac MRI especially in small and highly mobile masses.

Our case report serves to highlight this unique presentation of an exceedingly rare intracardiac tumour.

Lead author biography

Dr Jonathan Ong graduated from the Yong Loo Lin School of Medicine, National University of Singapore in 2012. He obtained his Masters of Medicine and MRCP (UK) in 2016 and attained specialist accreditation in Cardiology in 2022. He currently works as an Associate Consultant in National Heart Centre Singapore. His subspecialty interest is in Electrophysiology and Pacing.

Supplementary material

Supplementary material is available at European Heart Journal – Case Reports online.

Acknowledgements

Uppaluri Srinivas Anandswaroop (Senior Consultant, Department of Radiology, Sengkang General Hospital, Singapore) for his assistance in CT image interpretation.

Consent: The authors confirm that written consent for submission and publication of this case report including images and associated text has been obtained from the patient in line with COPE guidance.

Funding: None declared.

Data availability

The data underlying this article are available in the article and in its online Supplementary material.

References

Author notes