In this article, we will discuss about various Investigations required for diagnosing Pulmonary Venous Thromboembolism. So, let’s get started.
Investigations
The chest x-ray may be normal; however, in case of positive x-ray following findings are frequently noted:
Atelectasis
Elevated hemidiaphragm
Enlargement of cardiac shadow
Enlarged pulmonary conus
Pleural effusion
Lung consolidation
Avascular lung zone (Westermark sign), wedge-shaped opacity above hemidiaphragm (Hampton’s hump) and enlarged right descending pulmonary artery (Palla’s sign) are also noted in the chest x-ray.
The ECG may be normal in mild to moderate cases with 70-80% cases just show sinus tachycardia. In severe cases, ECG shows P pulmonale wave acute right ventricular strain (T wave inversion in V1-V4) or myocardial ischemia (ST-segment depression I and II) or both. Right axis deviation and clockwise rotation are common. the SIQIII, TIII syndrome in which there is S wave in lead I and Q wave in lead III with inversion if present is highly suggestive of acute pulmonary embolism. The transient development of incomplete RBBB is indicative of acute pulmonary embolism. Recurrent episodes of arrhythmias, sinus tachycardia, atrial fibrillation may also occur.
Arterial blood gas analysis shows hypoxemia with respiratory alkalosis.
CT pulmonary angiography is considered a gold standard for the diagnosis of pulmonary embolism. It provides direct visualization of intraluminal filling defects or abrupt cut-off the vessel caused by pulmonary embolism.
Plasma D-dimer analysis helps in the diagnosis of pulmonary embolism.
The 2-D echocardiogram reveals right ventricular dilatation/dysfunction, hypokinesia, septal flattening, and tricuspid regurgitation.
Radioisotopic ventilation-perfusion ratio (V/Q scan) is the second line diagnostic test for pulmonary embolism. The hypoperfusion or under-perfused area of the lung is shown as cold spots or avascular zone in the scan. A high probable scan is defined as two or more segmental perfusion defects with normal ventilation indicates pulmonary embolism.
Spiral contrast chest CT is the principal imaging test for the diagnosis of pulmonary embolism. This approach is best suited for the identification of the emboli that are situated in the proximal pulmonary vessels; however, is unsuitable for the identification of emboli present in the distal vascular bed.
Diagnostic test (Doppler ultrasound, impedances plethysmography, contrast venography, contrast MRI, etc) which confirms the diagnosis of DVT raises the possibility of pulmonary thromboembolism.