We describe a case report observed via an echocardiography of a venous thromboembolism (VTE) that crosses through the patent foramen ovale to the left atrium and is successfully treated with alteplase. This is a case report of a tertiary care hospital without cardiac surgery facilities. An 81-year-old female seeking medical attention for dyspnoea, arriving at hospital with hypoxaemia, hypotension and prerenal failure. A computed tomographic (CT) pulmonary angiography was carried out, revealing a VTE. A transesophageal echocardiography (TEE) was carried out, exposing emboli in the right cavities, said thrombus crossing through the patent foramen ovale to the left atrium. A systemic thrombolysis is carried out using alteplase which improves the patient's condition and results in the disappearance of thrombotic images in the various cardiac cavities. The evolution is positive and there is no evidence of embolic or haemorrhagic complications. When a paradoxical embolism is present, in the context of a serious VTE, carrying out thrombolysis could be a therapeutic option.