Left atrial dissection usually acts as a complication of mitral valve replacement surgery and results in a cavity within the wall of the left atrium. In severe cases, hemodynamic collapse sometimes happens and needs immediate surgical intervention. Here, we present a case of severe mitral valve obstruction caused by left atrial dissection, which is successfully handled by surgical treatment.
A 44-year-old man was admitted to the hospital because of exertional dyspnoea, lower extremity edema, diarrhea, and cachexia. Blood tests were unremarkable excepting eosinophilia. Echocardiogram noticed a large mass in the left atrium with smooth edges, thickened wall, and a central cavity [Figure 1A] [Supplementary Video 1, https://links.lww.com/CD9/A6], leading to mitral valvular orifice obstruction [Figure 1B] [Supplementary Video 2, https://links.lww.com/CD9/A7]. A perforation was observed at the root of the posterior mitral leaflet, with an abnormal shunt from the left ventricle to the cavity [Figure 1C]. Besides hydrothorax, intrahepatic and extrahepatic bile duct dilatation, and celiac lymphadenopathy, computed tomography also confirmed an occupation in the left atrium [Figure 1D and 1E], which is consistent with the finding of echocardiogram and made the evidence solid.
Due to the severe mitral valvular orifice obstruction and the status of cardiogenic shock, this patient underwent an emergency thoracotomy. Different from echocardiographic findings, surgery corrected the perforation locating on the basal posterior wall of the left ventricle, adjacent to the root of the posterior mitral valve [Figure 1F], which resulted in a sub-endocardial dissection of the left atrial wall and followed by a pseudinoma in the left atrium [Figure 1G], as well as mitral valvular orifice obstruction. Hence, left atrial mass resection, left ventricular posterior wall repairment, mitral annular reinforcement, and mitral valvuloplasty were conducted [Figure 1H].
A further epidemiologic investigation revealed an addiction history of 7 years to raw food such as frogs and tadpoles. However, surgical cardiac histopathology only noticed endocardial hematoma with nonspecific inflammation, and no microbial pathogen could be found. For highly suspecting parasite infection, repeated tests of stools were performed. Eventually, several parasite eggs were identified in the patient's feces, including eggs of liver fluke, heterophyidae fluke, and echinoderm fluke. The combination of the clinical history of omophagia, parasite eggs in the stool, and left atrium dissection were discussed by a multidisciplinary team meeting, and the diagnostic agreement of parasite infection by food-borne trematodiases was reached. This patient was then prescribed deworming medications containing praziquantel and dexamethasone and recovered very well after a follow-up of 3 years.
Here, we reported a case with surgical findings of left atrial dissection, left ventricular endo-myocardial perforation, and mitral valvular obstruction. Left atrial dissection is rare with a reported prevalence of 0.16%, which is often seen as a surgical complication of mitral valve replacement. However, in this case, mass formed in the atrium leads to mitral valve obstruction and results in left atrial dissection in a mechanical way. Parasite infection is not confirmed but suspected, which may migrate through the peripheral circulation to the heart and colonized on the left ventricular endo-myocardium below of the mitral posterior valve, where the velocity of blood flow is relatively low. Therefore, the basal posterior wall of the left ventricle might be vulnerable to worms. Following clues will be helpful to indicate cardiac parasite infection. Firstly, the parasite can lead to several cardiac injuries such as myocarditis, valvular disease, and heart failure simultaneously. Secondly, patients with parasite infection are usually manifested as multiple system involvement, such as hepatosplenomegaly, lymphadenopathy, polyserositis, recurrent fever, and eosinophilia. More importantly, most of them are characterized by diarrhea, emaciation, and edema. Lastly, special personal history matters, such as addiction to frogs or raw seafood.
Conflicts of Interest
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