There are well known visual signs that are associated with the ischemia of advanced PAD, and these are taught to podiatrists and medicos as part of standard medical education. However, these signs are often mistakenly over-relied on in screening and diagnosis, as they are not present in early disease. The visual signs listed below are in fact, evidence only of peripheral ischemia, a secondary manifestation of late peripheral artery disease. In fact, many people with clinically important PAD are asymptomatic and have no visual signs at all.
The IWGDF guidelines 2019 gives the following recommendations:
- Clinical visual examination alone is insufficient to exclude PAD
- The presence of pulses does not exclude PAD
- Monophasic Doppler is useful to indicate PAD
- An ankle-brachial index (ABI) in the normal range does not exclude PAD
- Use the ‘WIfI’ classification with toe pressures; recommended for risk evaluation for people with a history of ulceration.
Visual signs indicate peripheral ischemia and only appear in late disease
Visual signs are not valid to screen for clinically important PAD and are not expected in primary PAD (which is the common and widespread vessel disease of atherosclerosis). Atherosclerosis may progress to advanced, life threatening stages before any ischemia of distal tissues occurs. In fact, many people have no visual signs but do have clinically important PAD, which confers risks to their mortality. https://twitter.com/PodiatryToday/status/1380503610451226627 See the featured case study for a clinical example.
Asymptomatic and invisible PAD occurs in silent, unappreciated disease and is potentially more dangerous for people, as they are less likely to have their modifiable cardiovascular risk factors addressed.
This is an exciting opportunity for podiatrists to take up to improve health outcomes in screening for vessel disease, which is the etiology behind cardiovascular disease: the greatest cause of mortality in Australia and worldwide. Statistics on this phenomenon are being presented in the next issue of STRIDE.