Paraguayan President Fernando Lugo, who has lymphatic cancer, was urgently transported from capital city Asuncion to a hospital in Brazil, after doctors detected a blood clot in a vein near his heart, officials said.
The health of the 59-year-old Lugo has, however, improved.
He "woke up without any problems, in good general condition," Alfredo Boccia, one of the doctors attending the president, said late Sunday.
The Office of the President said in a statement that Lugo, who is in the intensive care unit of Sao Paulo's Syrian Lebanese Hospital, will be thoroughly examined again.
After undergoing new tests Saturday night in Paraguay, doctors said Lugo had suffered a "thrombosis (stationary blood clot) in the superior vena cava due to a catheter installed to deal with the effects of the chemotherapy" which he has had recently.
The superior vena cava is a large diameter, yet short, vein that carries deoxygenated blood from the upper half of the body to the heart's right atrium.
"Given the said diagnosis, specific clinical treatment has been initiated with 'auspicious' results," the statement said.