Dr. Usman's Cardiology Notes

 Pericardial Fat Pad Mimicking Cardiomegaly: Cause of Increased Cardiothoracic Ratio on Chest X-Ray Introduction An increased cardiothoracic ratio (CTR) on chest X-ray (CXR) is commonly interpreted as cardiomegaly. However, not all apparent cardiac enlargement reflects true cardiac pathology. One important and often overlooked cause is a pericardial fat pad, which can enlarge the cardiac silhouette without any increase in actual heart size. Recognizing this entity is essential to avoid misdiagnosis and unnecessary investigations. --- What Is a Pericardial Fat Pad? Pericardial fat refers to adipose tissue located: Epicardial fat: between the myocardium and visceral pericardium Paracardial (mediastinal) fat: outside the parietal pericardium When excessive, this fat can project over the cardiac borders on CXR, producing a falsely increased CTR. --- Why It Increases CTR on Chest X-Ray CTR is calculated as the ratio of maximal transverse cardiac diameter to maximal thoracic diameter (no...

A 68 year old female with atrial fibrillation and dementia presented to the hospital with sudden onset of dyspnea that had begun 1 hour earlier. Before admission, he had not been taking anticoagulation therapy on the basis of discussions of his preferences with his primary care physician. Physical examination was notable for tachypnea and tachycardia. On chest radiography, the pulmonary vasculature was not visible in the right lung fields. In addition, the right descending pulmonary artery was enlarged. These radiograph findings display Westermark’s sign, which indicates an area of oligemia distal to a pulmonary embolism, and Palla’s sign, an enlargement of the right descending pulmonary artery. Computed tomographic (CT) pulmonary angiography of the chest confirmed the presence of pulmonary emboli in both pulmonary arteries, predominantly on the right side. The CT scan also showed oligemia in the lung parenchyma on the right side. Source: NEJM