“Double Ball Valve Mechanism Obstructing Both Right Ventricular Inflow and Outflow”: Atypical Presentation of Right Atrial Myxoma Presenting as Right Ventricular Mass

Abstract

Large intracavitary masses such as those occupying most of a cardiac chamber and obstructing blood flow are not routinely encountered in clinical practice. The differential diagnosis includes neoplastic as well as nonneoplastic causes. Primary cardiac tumors by themselves are uncommon. We hereby report a rare case of a middle-aged female presenting with New York Heart Association Class III symptoms, whose transthoracic echocardiogram revealed a huge mass in right-sided chambers with a novel double ball valve type movement. She successfully underwent urgent surgical resection of the mass with histopathological confirmation of diagnosis.

INTRODUCTION

Intracardiac masses are readily detected by echocardiography. Most common masses are thrombus, vegetation, and tumors. However, very large masses such as occupying most of a chamber and causing inflow/outflow obstruction are uncommonly encountered in clinical practice. Nonneoplastic causes of such large masses include large thrombi, fungal ball, and rare case reports of tuberculoma, hydatid cyst, and giant eustachian valve. Neoplastic causes of a large cardiac mass in order of frequency include metastatic deposits and primary cardiac tumors such as myxomas, lipomas, sarcomas, and lymphomas.

CASE PRESENTATION

A 37-year-old female presented with complaints of gradually progressive effort intolerance, and dyspnea on exertion for the past 1½ years (New York Heart Association Class III on presentation). She also reported weight loss of about 10 kg over the past 1 year. She denied any history of prolonged fever, cough, expectoration, any swelling over body, tremors, palpitations, intolerance to heat or cold, menstrual irregularities, change in dietary, and bowel or bladder habits. There was no relevant past history or family history.

On general examination, she appeared thin with mild pallor and a body mass index of 19 kg/m ². She was afebrile, with heart rate 88 bpm, blood pressure 110/84 mmHg in the left upper arm, and raised jugular venous pressure with normal waveform. Cardiovascular examination revealed a normal apex beat, a soft first heart sound, normally split second heart sound, and a soft mid-diastolic murmur on left lower sternal edge. Lung fields were clear. Abdomen and neurological examination was normal. Extremities showed no edema, clubbing or cyanosis.

Electrocardiogram suggested right atrial enlargement. Chest radiograph showed slightly enlarged right atrium (RA) with diminished pulmonary vascular markings. Hemoglobin was 10.1 g/dl; white blood cell count and liver and renal function tests were normal.

Transthoracic echocardiogram revealed a huge mass measuring 8.6 cm × 4.6 cm in right-sided chambers occupying RA, whole of RV extending up to RV outflow tract (RVOT) [Figure 1]. The mass had an inhomogeneous echodensity with a lobulated appearance. It was highly mobile and obstructing RV inflow as well as outflow staging the “double ball valve phenomena”– a single mass staggering to-and-fro across tricuspid valve and RVOT [Videos 1 and 2]. Left-sided chambers were normal with normal left ventricular function. A provisional diagnosis of large RA/RV mass was kept with thrombus or tumor as differentials. Venous Doppler of both lower limbs and abdomen did not show any evidence of venous thromboses. Abdominal ultrasound was within normal limits.

Figure 1.

Transthoracic two-dimensional echocardiogram. (a) Apical four-chamber view showing huge inhomogeneous lobulated mass in right atrium-right ventricle obstructing tricuspid flow. (b) Parasternal short axis view at aortic valve level showing mass obstructing right ventricle inflow as well as right ventricle outflow tract – double ball valve obstruction. A1 / B1 - diastolic images, A2 / B2 - systolic images

Chest and cardiac computed tomography (CT) scan was done, and it revealed an inhomogeneous lobulated mass occupying RA and RV measuring 8.5 cm × 5 cm [Figure 2]. The point of attachment of the mass could not be ascertained. There were no mass lesions in lung fields.

Figure 2.

Cardiac computed tomography. (a) Right ventricle inlet-outlet view showing large mass occupying almost whole of right atrium-right ventricle and obstructing both inflow and outflow, (b) Four-chamber view showing lobulated mass

Patient underwent surgery under cardiopulmonary bypass, and a 9 cm × 5 cm × 5 cm, 122 g, semi-gelatinous yellowish-brown lobular mass, mottled with hemorrhage was carefully resected [Figure 3]. It was found to be attached to fossa ovalis. She was extubated after 24 h and made an uneventful recovery. Histopathological examination confirmed the presence of globular myxoma cells and vessel-like structures embedded within an abundant acid mucopolysaccharide ground substance characteristic of myxoma tumor [Figure 4].

Figure 3.

Resected mass. Gelatinous yellowish-brown lobular mass, mottled with hemorrhage

Figure 4.

Histology. Globular cells (a) and vessel-like structures (b) embedded within an acid mucopolysaccharide ground substance characteristic of myxoma

Postsurgical and predischarge echocardiogram showed no evidence of residual myxoma. There were normal RV function, mild tricuspid regurgitation, and normal pulmonary valve function. Patient was discharged on 5^th postoperative day.

DISCUSSION

Primary cardiac tumors are rare across all age groups, with reported prevalence of 0.001%–0.03% in autopsy series; in contrast, secondary tumor metastasis to heart occurs 20–40 times more commonly, in up to 1% of all cancer patients, and up to 5% patients dying of malignancy.[1] About 75% of all primary cardiac tumors are regarded as benign neoplasms, and about 50% of all these are myxomas. According to their anatomical location, these tumors produce obstructive, systemic, and embolic manifestations, which may even be fatal.[2]

In a meta-analysis of more than 1000 cardiac myxoma patients, left atrial location was present in 83%, right atrial in 12.7%, and biatrial in 1.3%. Rarely tumor occurred in right (1.7%) or left (0.6%) ventricle.[3] In our case also, tumor was found to be attached to fossa ovalis toward RA.

Any valve that allows flow in one direction but checks flow in the opposite direction by seating of a ball on opening is having a “ball valve mechanism.” The to-and-fro movement of pedunculated myxoma may give rise to this typical “ball valve obstruction.” In our patient, due to huge size of tumor, the tricuspid valve as well as RVOT, both were getting obstructed by a single mass and gave rise to clinical signs and symptoms.

Cardiac masses are one of the most challenging diagnostic entities because of uncommon occurrence and nonspecific clinical presentations. A thorough evaluation including a complete history, physical examination, appropriate laboratory tests, transthoracic/transesophageal echocardiography, and CT/magnetic resonance imaging is necessary to help support a possible diagnosis of a nonneoplastic mass or a primary or secondary cardiac tumor.[4,5] In our case also, final diagnosis is reached only after surgery and histopathological examination. A general approach to initial differential diagnosis is tabulated in Table 1.

Table 1.

Cardiac masses differential - by site, frequency and general imaging characteristics

CONCLUSION

Cardiac masses are readily identified by echocardiography. Primary cardiac tumors are rare but should always be considered in their differential diagnosis.

LEARNING OBJECTIVE

Large intracavitary masses obstructing blood flow have a differential diagnosis including neoplastic as well as nonneoplastic causes. Right atrial myxoma could present as a huge mass with right ventriclular inflow as well as outflow obstruction. Echocardiography plays a key role in diagnosis and planning management.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.