Pulmonary thromboembolism in a patient with myotonic dystrophy type 1
A 38-year-old man was transferred to our emergency room for shortness of breath. Two hours before admission, he began to have sudden onset of dyspnea, and was intubated in another hospital. He reported to be healthy before this episode, and systemic review was negative. He did not have a remarkable past medical history, including surgery, allergy or specific medications. However, he had a family history of ischemic stroke; his father died of complication of ischemic stroke at the age of 65 years and his brother had ischemic stroke at the age of 39 years.\nIn the emergency department, he had respiratory distress and tachycardia, with an oxygen saturation of 81% even under the intubated state. The blood pressure fell to an unmeasurable level, and the heart rate was 102 beats/min. There were crackles in both lungs on auscultation. Chest X-ray revealed mediastinal widening and cardiomegaly with bilateral infiltrations. Computed tomography (CT) of the chest showed dilated pulmonary trunk, but there was no evidence of pulmonary thrombus, aortic dissection or lymphadenopathy. The patient was admitted to the intensive care unit with a tentative diagnosis of acute respiratory failure due to severe pneumonia.\nOn hospital day 3, chest X-ray showed decreased infiltration and vital signs were stabilized. However, he developed sudden onset of tachypnea and hypotension on the next day. Arterial blood gas analysis results while breathing ambient air were pH 7.21, PaO2 50.0 mmHg, PaCO2 71.4 mmHg and oxygen saturation 76%. A follow-up chest CT revealed a large thrombus in the right main pulmonary artery and marked dilatation of the pulmonary arteries []. In addition, atrophy of pectoralis and paravertebral muscles was detected []. Transthoracic echocardiogram (TTE) showed pulmonary arterial hypertension (right ventricular systolic pressure 60 mmHg) with D-shaped left ventricle. However, echocardiographic evidence of a thrombus was not identified.\nThe patient received thrombolytic therapy followed by subcutaneous low-molecular weight heparin, and his symptoms improved with the treatment. Screening tests for hypercoagulable state including protein C, protein S and anti-thrombin III were normal. Lupus anticoagulant, anti-cardiolipin antibodies and factor V Leiden mutation tests were also negative.\nDuring the admission, neurologic examinations performed by a consultant neurologist revealed mild ptosis in both eyes, frontal baldness, temporal wasting, elongated face, weakness of distal upper extremities and percussion myotonia. Electromyography showed typical myotonic discharges in proximal and distal extremities, consistent with myotonic dystrophy. The diagnosis of myotonic dystrophy type 1 was subsequently confirmed by an expansion of CTG repeat on chromosome 19. He was discharged to a rehabilitation facility, at which time he was functioning independently with nocturnal non-invasive ventilation.