Laboratory and instrumental methods of diagnosis of PE Pulmonary embolism is diagnosed using varieties of techniques such as chest X-ray, blood gas analysis and an electrocardiogram, D-dimer, echocardiography, spiral computed tomography, contrast-enhanced (CT angiography) of the chest, ventilation-perfusion lung scintigraphy, angiography, and other methods of diagnosis of thrombosis of deep lower limbs (ultrasound, CT venography). Electrocardiography (ECG) is most widely used method of investigation for PE. The ECG investigation shows the present of arrhythmias, conduction disorders , voltage and complex ventricular repolarization process, signs of overload of the right heart. Acute pulmonary embolism leads to the sudden appearance of pulmonary hypertension and development of acute pulmonary heart disease . The following signs have been shown on ECG in patients with pulmonary embolism: Q III -S I (QR III -RS ...