Right ventricular apical thrombus detected by transthoracic echocardiography: impact of right ventricular modified apical four-chamber view

Abstract

An 86-year-old woman was admitted to our hospital because of persistent dyspnea developing three days ago. She was receiving treatment for chronic myeloproliferative disorders with hydroxycarbamide. Electrocardiography showed T-wave inversion in leads II, III, aVF, and V1–V4. Blood test showed elevated levels of D-dimer (4.5 μg/mL). Transthoracic echocardiography (TTE) showed preserved left ventricular ejection fraction (58%), however, parasternal short-axis view (PSAX) showed a D-shaped deformation of the left ventricle. The right ventricle (RV) was dilated, with reduced contractility (TAPSE: tricuspid annular plane systolic excursion 13 mm). Continuous-wave Doppler imaging showed a tricuspid valve regurgitation (TR) velocity of 3.3 m/s. PSAX, apical four-chamber view (A4C), and RV-focused A4C showed no abnormality in the RV cavity (Fig. 1a, b). RV-modified A4C revealed an iso-high echoic mass (18 × 15 mm) in the RV apex (RVA) (Fig. 1c). The mass had a round margin and poor mobility and was attached to the RV wall. Echocardiographic differential diagnosis was a thrombus or myxoma [1]. Contrast-enhanced computed tomography revealed pulmonary artery embolism and deep vein contrast defect in both legs. Heparin (17,500 U/day) was administered. TTE was scheduled weekly after anticoagulant therapy. The mass gradually shrank. In the third week, the RVA mass disappeared (Fig. 1d), which indicated that the mass was a thrombus complicated by pulmonary artery thromboembolism and deep vein thrombosis. TAPSE recovered to the normal range (18 mm) and the TR velocity was reduced to 2.7 m/s. Afterwards, She had an uneventful course. Right heart thrombus complicates 4–18% of acute pulmonary embolism cases [2], increasing the mortality to > 44% [3]. Most RV thrombi originate from peripheral veins, protrude around the RV inflow-outflow towards the lungs, and a worm-like shape mass is detected by TTE [4]. A RV thrombus formed in situ is rare [1]. The guidelines of the American Society of Echocardiography show three types of A4Cs (routine A4C, RV-focused A4C, RV-modified A4C) (Fig. 1a’–c’) [5]. In this case, RV-modified A4C revealed a thrombus in the RVA, indicating in situ thrombus formation. the whole RVA cannot be visualized by routine PSAX because of RV dilatation. Likewise, routine screening of the A4C and RV-focused A4C can only visualize limited areas of the RVA (Fig. 1a, b). RV-modified A4C is visualized by sliding the echo probe slightly toward RVA and is an essential view that complements routine TTE screening in suspected cases of pulmonary thromboembolism, especially those with RV dilatation.