Cardiomegaly on CXR
Cardiomegaly on CXR: X-ray chest PA view showing cardiomegaly. Right pulmonary artery (RPA) and right atrium (RA) are prominent. Tracheal shadow is seen in the mid line. Lower down, trachea is seen dividing into a more horizontal left bronchus (LB) and a more vertical right bronchus (RB). Aortic knuckle (Ao) is seen along the left upper border. Tracheal indentation on the left side at the lower end by the aortic arch can be appreciated near the tracheal bifurcation.
Upper lobe vessels (ULV) are prominent. Since it is difficult to make out whether the prominent upper lobe vessels are arteries or veins, usually they are called just like that. Most often in this context they are dilated veins due to pulmonary venous hypertension secondary to elevated left atrial pressure and pulmonary capillary pressure. Prominent upper lobe vessels have other eponyms: cephalisation, antler sign, inverted mustache sign and redistribution. Cephalisation and redistribution indicate the change from the normal pattern in which lower zone vessels are more prominent than the upper zone vessels, due to the effect of gravity. When there is pulmonary venous hypertension, lower zone vessels are constricted and there is a redistribution of flow to the upper zones. The antler sign is so named because of the resemblance of the upper lobe vessels to the horns of the antler.