How ECG can cause confusion in pulmonary embolism and how echocardiogram can help

Abstract

A case of pulmonary embolism in which the diagnosis was aided by transthorasic echocardiography is described. Echocardiography may be helpful in emergency presentations, as ECG changes can be neither sensitive nor specific for the diagnosis of acute massive pulmonary embolism.A 25 year old man presented with a 1 week history of non-productive cough and shortness of breath on exertion. Over the preceding month, he had experienced intermittent palpitations on several occasions. He had received antibiotics from his general practitioner for cellulitis in the left leg. There was no history of chest pain or haemoptysis. Past medical history was of mild asthma. There was no significant family history of medical problems. He was a non-smoker and occasionally drank alcohol.Examination revealed a moderately built man, who was apyrexial, tachypnoeic, and tachycardic, but not in respiratory distress. Blood pressure was 135/85, pulse regular and 110 beats/min, respiration rate 20 breaths/min, O 2 saturation 94% (on 2 litres of O 2 ). Chest auscultation revealed a loud second heart sound. An ejection systolic murmur was heard at the left sternal edge radiating to the neck. The chest was clear. There was minimal oedema of the left leg, with a swollen but non-tender calf. There were no abnormal abdominal or CNS findings.Blood results were: haemoglobin 16 g/l, white cell count 14.4610 9 /l, platelets 226610 9 /l, D-dimer 2 U (normal range 0-0.5). Troponin T and thrombophilia screens were negative. Arterial blood gases showed PO 2 of 10 kPa, PCO 2 of 3.9 kPa, and pH of 7.42. Chest x ray revealed enlarged pulmonary arteries, and ECG showed left axis deviation and anteroseptal ST/T depression (fig 1).A diagnosis of pulmonary embolism (PE) was made and anticoagulation with tinzaparin was initiated, followed by warfarin treatment. An early transthoracic echocardiogram revealed dilated right heart chambers with good left and right ventricle function and mild to moderate tricuspid regurgitation with estimated pulmonary artery systolic pressure of 68 mmHg. There was paradoxical septal motion due to right heart dilatation. A subsequent V/Q scan detected a number of significant unmatched perfusion defects in the left lung and one on the right, suggesting a high probability of PE.The patient made a good recovery and was allowed home with continuing warfarin treatment. DISCUSSIONThis case highlights the value of early echocardiogram in the diagnosis of acute massive PE. PE is both underdiagnosed and overdiagnosed. Acute PE causes up to 10% of all hospital deaths, with most occurring because of a delay in diagnosis, as PE is easily missed in elderly patients, patients with cardiorespiratory disease, and those presenting with isolated dyspnoea. A high index of suspicion is required to achieve an accurate diagnosis.Most ECG features in PE lack specificity and sensitivity, and the value of ECG for the diagnosis of PE is debatable. ECG can be normal in pulmonary embolism, and other recognised features of include sinus tachycardia (heart rate .10...