A Stunning Giant Mass in Right Ventricle: A Challenge for Treatment

A 61-year-old man with a history of partial liver resection 2 years previously for hepatocellular carcinoma (HCC) was referred to our university hospital from an outside clinic. He was experiencing dyspnea on exertion and had New York Heart Association functional class III heart failure. Emergency laboratory examination revealed a substantial rise in the levels of coagulation markers (D-dimer level, 6.48 mg/L; fibrin degradation product level, 19.8 μg/mL) and an obvious increase in N-terminal pro-B-type natriuretic peptide levels to 2,035 pg/mL. Analysis of tumor marker levels indicated an elevated cancer antigen-125 level of 275.10 U/mL, and a normal α-fetoprotein level (1.86 ng/mL). ECG at admission showed a right bundle branch block and right axis deviation. A CT scan of the thorax and abdomen revealed no suspicious nodules in the liver. Subsequently, transthoracic echocardiography (TTE) was performed (Fig 1, Video 1). Question 1: What is the differential diagnosis for this patient, based on clinical history and the TTE findings in Video 1, and what is the next step in diagnosis? Question 2: How should pacemaker implantation be carried out, considering the presence of residual tumor tissue in the right ventricle? Answer to Question 1: The differential diagnosis included thrombus or isolated right ventricular metastasis of HCC. The next step in diagnosis is contrast echocardiography (CE). CE was performed after 2 days of anticoagulation therapy. The mass had not decreased in size. It showed contrast hyperenhancement compared with the surrounding myocardium after the administration of a contrast agent, suggesting a highly vascular or malignant tumor (Fig 2, Video 2). Because of his progressive dyspnea, the patient required surgical resection of the mass to relieve the obstruction of the right ventricular outflow tract (Fig 3). The tricuspid valve was replaced with a bioprosthetic valve (Mosaic valve, 27 mm; Medtronic). Histopathology of the surgically extracted masses revealed HCC metastasis (Fig 3). Recovery went well until postoperative day 27, when the patient experienced sudden ventricular tachycardia (VT) followed by dyspnea, undetectable BP, and transient dilation of the pupils. After successful electrical cardioversion, the patient recovered consciousness. Considering that 24-hour Holter ECG detected atrioventricular block (AVB) before this emergency, VT occurred secondary to AVB. A risk of Adams-Stokes syndrome and sudden death remained. Therefore, permanent pacemaker implantation was necessary. Answer to Question 2: Because of the residual tumor tissue in the right ventricle (RV), it was impossible to carry out traditional RV pacing, and the patient could not undergo full sternotomy again for epicardial pacing. Here, after comprehensive and careful evaluation, the electrophysiologist decided to use the transseptal approach with a new pacing technique (pacing leads [model 3830; Medtronic] delivered through a fixed-curve sheath [C315HIS; Medtronic]) (Fig 4, Video 3). Left ventricular septal myocardial pacing (LVSP) was then confirmed by intracavity electrogram (GE Healthcare). The patient did not experience cardiac arrhythmia over 8 months of follow-up. In this extraordinary case, a patient with a metastatic relapse of HCC and a prominent RV mass received implantation of a special permanent pacemaker after surgical debulking and tricuspid valve replacement. The incidence of intraventricular masses is generally low (the estimated prevalence is 0.195%).1Bugra Z. Emet S. Umman B. et al.Intracardiac masses: single center experience within 12 years: I-MASS Study.Am Heart J Plus. 2022; 13100081Google Scholar Intracardiac thrombus represents the most commonly encountered intraventricular mass in clinical practice; however, the differential diagnosis includes neoplastic masses, including primary cardiac tumors as well as intracardiac metastases.1Bugra Z. Emet S. Umman B. et al.Intracardiac masses: single center experience within 12 years: I-MASS Study.Am Heart J Plus. 2022; 13100081Google Scholar HCC most commonly metastasizes to the lungs, followed by the intraabdominal lymph nodes, bones, adrenal glands and, rarely, the brain.2Uka K. Aikata H. Takaki S. et al.Clinical features and prognosis of patients with extrahepatic metastases from hepatocellular carcinoma.World J Gastroenterol. 2007; 13: 414-420Crossref PubMed Scopus (301) Google Scholar, 3Choi H.J. Cho B.C. Sohn J.H. et al.Brain metastases from hepatocellular carcinoma: prognostic factors and outcome: brain metastasis from HCC.J Neurooncol. 2009; 91: 307-313Crossref PubMed Scopus (89) Google Scholar, 4Katyal S. Oliver III, J.H. Peterson M.S. Ferris J.V. Carr B.S. Baron R.L. Extrahepatic metastases of hepatocellular carcinoma.Radiology. 2000; 216: 698-703Crossref PubMed Scopus (534) Google Scholar Tumors can spread to the heart through four alternative paths: by direct extension, through the bloodstream, through the lymphatic system, and by intracavitary diffusion through either the inferior vena cava or the pulmonary veins. However, isolated RV metastasis without right atrial and inferior vena cava involvement is extremely rare.5Bussani R. De-Giorgio F. Abbate A. Silvestri F. Cardiac metastases.J Clin Pathol. 2007; 60: 27-34Crossref PubMed Scopus (415) Google Scholar CE helps us easily distinguish thrombi from tumors. Tumors show contrast hyper- or hypoenhancement whereas thrombi show no enhancement. Although cardiac MRI is more useful in the identification of the nature of a cardiac mass, CE is more rapid and convenient, especially in patients who are not able to tolerate cardiac MRI or who have contradictions for MRI. The usefulness of CE has now been extended beyond the analysis of cardiac structure and functional assessment to evaluate perfusion of both the myocardium and the intracardiac structures. It has been demonstrated that this modality can be used to characterize the vascularity of cardiac masses and assist with the differentiation of malignant, highly vascular tumors from benign tumors or thrombi. Most malignancies have abnormal neovascularization that supplies rapidly growing tumor cells, often in the form of highly concentrated, dilated vessels.6Porter T.R. Mulvagh S.L. Abdelmoneim S.S. et al.Clinical applications of ultrasonic enhancing agents in echocardiography: 2018 American Society of Echocardiography guidelines update.J Am Soc Echocardiogr. 2018; 31: 241-274Abstract Full Text Full Text PDF PubMed Scopus (200) Google Scholar This patient was treated with surgical resection. Fan and colleagues7Fan C.T. Lin W.W. Chen M.J. Shiu S.I. Isolated right ventricular metastasis in a woman with advanced hepatocellular carcinoma after palliative therapy.Case Rep Gastroenterol. 2019; 13: 487-497Crossref PubMed Scopus (1) Google Scholar have reported that surgical resection for isolated metastatic HCC in the RV might be beneficial not only in alleviating symptoms but also in improving survival after an individualized and comprehensive evaluation. Treatments for cardiac mass are mainly surgical, and the prognosis is rather poor, with survival times ranging from 0 months (death immediately after surgery) to 9 months. Therefore, the prognosis remains poor.8Zhang X.T. Li Y. Ren S.H. et al.Isolated metastasis of hepatocellular carcinoma in the right ventricle.BMC Cardiovasc Disord. 2019; 19: 287Crossref PubMed Scopus (5) Google Scholar In this case, the tricuspid valve was infiltrated by metastatic HCC, and a bioprosthetic valve replacement was also performed. The atrioventricular node is known to reside in the triangle of Koch, which borders the septal leaflet of the tricuspid valve. Because of these anatomic features, atrioventricular nodes are highly susceptible to damage and result in a risk of AVB. In this case, AVB was detected, and VT and a cardiac emergency occurred. Permanent pacemaker implantation was necessary to reduce the risk of sudden death. Traditional RV pacing methods were not applicable. Electrophysiologists have developed 3830 pacing leads, which can be screwed deep into the basal segment of the septum, bypassing residual tumor tissue in the right ventricle. More recently, newer pacing techniques such as His-Purkinje conduction system pacing have emerged. LVSP and direct capture of the left Tawara bundle (left bundle branch pacing), using the transseptal approach, have been described.9Huang W.J. Su L. Wu S.J. et al.A novel pacing strategy with low and stable output: pacing the left bundle branch immediately beyond the conduction block.Can J Cardiol. 2017; 33: 1736.e1-1736.e3Abstract Full Text Full Text PDF PubMed Scopus (371) Google Scholar According to the appearance of the ECG,10Jastrzębski M. Kiełbasa G. Curila K. et al.Physiology-based electrocardiographic criteria for left bundle branch capture.Heart Rhythm. 2021; 18: 935-943Abstract Full Text Full Text PDF PubMed Scopus (69) Google Scholar we finally confirmed LVSP. The patient did not experience cardiac arrhythmia over 8 months of continued follow-up. See Narration Video for a detailed explanation of Videos 1-3. 1.Physicians should be aware of the potential risk of isolated right ventricular metastasis in patients with hepatocellular carcinoma, even after standard partial hepatectomy.2.Understanding contrast echocardiography helps easily distinguish thrombi from tumors.3.Early surgical debulking should be considered to improve symptoms; pacemaker implantation prevents sudden death and improves survival. This study was supported as a Xiamen Key Project of Medical and Health Sciences (3502Z20191103) and as a Science and Technology Planning Project of Xiamen (3502Z20214ZD2183).