What is the likely diagnosis?
Congestive cardiac failure and interstitial oedema.
What are these lines called? What do they represent?
Kerley B lines. They represent fluid accumulating in the interlobular septae.
What do Kerley A lines represent?
2 - 6 cm long oblique lines that are < 1 mm thick and course towards the hilar. They represent thickening of the interlobular septa that contain lymphatic connections between the perivenous and bronchoarterial lymphatics deep within the lung parenchyma.
The heart is enlarged and permanent pacemaker (PPM) is in situ. The interstitial marking of the lungs are increased with numerous peripheral horizontal lines abutting the lateral pleura.