PMC9262377_01
Coronary angiography. (A) Left coronary artery showing abnormal vascular structures (arrow) suggestive of arteriovenous fistula and a highly vascularized mass. Marginal branch demonstrates proximal 90% obstruction (Supplementary Video 1). (B) Right coronary artery shows no obstruction, abnormal vascular structures are also present (arrow).
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The study showed abnormal and significant neovascularization within the left atrium and a 90% obstruction at the origin of the marginal branch, which suggested neovascularization of an atrial mass. (Figures 1A,B and Supplementary Video 1).
Echocardiogram. (A) 2D-TTE four-chamber view shows a large echogenic oval mass that occupies practically the entire left atrium, with regular borders, heterogeneous echogenicity, adhered to the interatrial septum by a short pedicle and moderate to severe mitral regurgitation in the color Doppler. (B) 2D-Transesophageal echocardiogram and color-Doppler evidenced significant vascularization inside the mass. (C) 3D-TTE shows the mass protruding through the mitral valve into the left ventricle during end-diastole (Supplementary Video 2). Ao, aorta; RA, right atrium; RV, right ventricle; TTE, transthoracic echocardiogram; TV, tricuspid valve.
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TAPSE-21 mm). Two dimensional-Doppler-transesophageal echocardiography showed a giant vascularized heterogeneous mass. 3D-TTE accurately identified the mass protruding through the mitral valve into the left ventricle during end-diastole and the 2D-TTE color flow and continuous wave Doppler in four chamber view showed a diastolic mitral peak velocity of 2.08 m/s, maximum gradient of 17 mmHg and mean gradient of 10.33 mmHg (Figures 2A-C and Supplementary Video 2).
(A,B) Coronary Computed Tomography Angiography. Hypodense mass located in the left atrium attached to the interatrial septum, with a dense network of blood vessels within. The intra- atrial mass protrudes through the mitral valve into the left ventricle during diastole, causing impairment of the atrial emptying and mitral valve closure. (C,D) Coronary Computed Tomography Angiography reconstruction. Complex blood vessel network (arrows) anastomosed to branches of the circumflex artery and the right coronary artery (Supplementary Video 3). Ao, aorta; Cx, circumflex artery; LA, left atrium; LV, left ventricle; RCA, right coronary artery.
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After the echocardiographic findings, the heart team agreed on performing a CCTA, which showed a non-infiltrative and very vascularized mass attached to the interatrial septum (Figures 3A,B). A 3D-CCTA reconstruction additionally showed the significant vascularity of the tumor, characterized the anatomy of the coronary arteries and the origin of the neovascularization (Figure 3C). Double arterial blood supply was observed, with anomalous vessels arising from the right coronary artery and the circumflex artery (Figure 3D and Supplementary Video 3).
Macroscopic and microscopic specimen findings. (A) Oval mass of 80 grams, 7 x 4 x 5 cm of diameter with a smooth surface showing white/yellow colors with zones of hemorrhagic aspect. Intact capsule that delimits the entire mass, compatible with its benign and non-invasive nature. (B) On the left side, a pattern of glanduloid/vascular cavities with abundant inflammatory lymphocytic infiltrate. On the right side, homogeneous stroma with clear spaces and isolated myxoma cells with fusi morphology. H/E10x (C) Myxoma's stroma shows decreased cellular density and multiple blood vessels (asterisks). Stellate appearance cells present eosinophilic cytoplasm and round nucleus (white arrow). Syncytial Cells with a string morphology (black arrow). H/E 40x. (D) Follow-up echocardiogram. 2D and color flow TTE in four-chamber view with 2 jets of mild mitral regurgitation (white arrows) and no cardiac mass in the left atrium. Abbreviations as before.
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Pathologic findings were consistent with a LAM (Figures 4A-C). One month after surgery, a 2D-TTE demonstrated a diastolic mitral peak velocity of 0.67 m/s, maximum gradient of 1.79 mmHg, and mean gradient of 1.07 m/s and mild MR (Figure 4D).