This is the CXR of my toughest single chamber pacemaker cases, ever. (Used with patient permission).
It demonstrates massive right and left atrial enlargement from severe, longstanding mitral and tricuspid insufficiency. It also nicely demonstrates the "double-bubble" sign, with the right atrium outlined but the pacemaker lead descending down the margin of the right atrium from the superior vena cava, and the left atrial free wall nearly touching her right chest wall.
The patient was nearly 96 years old and collapsed while in her bathroom, striking her head and causing an asymptomatic subarachnoid hemorrhage while on coumadin for long-standing atrial fibrillation. She was found to have a regular junctional escape rhythm at 35-40 and was on no rate-slowing medications. Her lead dislodged six times during the case as it was forcefully ejected from the right ventricle. Fortunately, this morning she was doing well with great pacing thresholds.
Massive left atrial enlargement was also described by Ortner in the setting of mitral stenosis where the left atrium was so large that it compressed the recurrent laryngeal nerve as it passed beneath the tracheal bifurcation, giving rise to Ortner's Syndrome.
Ah, just another day at the office...