Case Report: Acute Intracardiac Thrombosis in Children With Coronavirus Disease 2019 (COVID-19) od Hamid Bigdelian, Hamid Bigdelian, Mohsen Sedighi, Mohammad Reza Sabri, Bahar Dehghan, Chehreh Mahdavi, Alireza Ahmadi, Mehdi Ghaderian, Hamid Rahimi, Atefeh Sadeghizadeh, Monirsadat Emadoleslami, Seyed Nasser Mostafavi, Rana Saleh, Niloofar Javadi, Maryam Derakhshan, Zahra Pourmoghaddas, Shima Sarfarazi Moghadam