What does the lucency to the left of the spinal column, with a radiopaque marker at its tip represent?
An intra-aortic balloon pump.
Has this film been obtained during systole or diastole?
As the balloon is inflated (with carbon dioxide) the film must have been obtained during diastole.
How does an intra-aortic balloon pump work?
As the balloon forcibly inflates it displaces blood both forwards and backwards, known as diastolic augmentation. As such it provides not only additional forward momentum to the blood in the distal descending aorta but more importantly increases perfusion to the vessels arising from the arch of the aorta, most importantly the coronary arteries which are perfused primarily during diastole. This has a dual effect: firstly it decreases left ventricular afterload, decreasing myocardial oxygen requirements, and secondly increases myocardial perfusion (during diastole)
Where should the tip of the balloon catheter be located?
Just distal to the origin of the subclavian artery (it is correctly positioned in this patient).
What other lines are present?
Endotracheal tube, Swan-Ganz catheter, ECG leads, temporary pacing leads, mediastinal / chest drain.
Intra-aortic balloon pump (partially inflated) in situ along with the usual post cardiac surgery lines (ETT, SGC, chest drain).