A young lady presented with an 8-day history of cramping pain in her right hand with ischaemic index and middle fingers (figure 1). Examination revealed no palpable pulses in the right upper limb, no aneurysms, thrills or audible heart murmurs. An electrocardiogram was normal. An arterial duplex scan showed turbulent waveforms in the subclavian artery and triphasic waveforms distally.
Arch angiography showed an aberrant right subclavian artery (figure 2) and small thrombi occluding the digital vessels of the index and middle fingers. She developed progressive lower-limb oedema and a venous duplex confirmed a non-occlusive thrombus in the right iliofemoral veins extending to the inferior vena cava.
A trans-thoracic echo showed poor views of the mitral and tricuspid valves and no obvious thrombus. However, a trans-oesophageal echo showed a patent foramen ovale (PFO) with bi-directional shunting, visible without having to perform a valsalva manoeuvre (video 1).
The digital ischaemia was ascribed to a paradoxical embolus via a PFO.
Paradoxical embolism is a rare cause of acute limb ischaemia.1 Probe patient PFO occurs in approximately 30% of the population, but larger defects able to admit the tip of a pencil occur in 7%.2
Trans-esophageal echo has a higher sensitivity (79%), specificity (75%) and positive predictive value (65%) than trans-thoracic echo (7%, 100% and 50%, respectively) in detecting a PFO.3
This highlights not only the need for a diagnosis in patients with acute ischaemia and no obvious source of emboli, but also the importance of trans-oesophageal echo in detecting PFO.