Cardiovascular Care

How podiatrists can shine: screening for peripheral artery disease

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7 min. reading time

Sylvia has been involved in a number of peer reviewed publications regarding peripheral vascular assessment. Her doctoral project involved using toe-brachial pressure indices to measure outcomes using transdermal glyceryl trinitrate. Now she provides podiatry services at a large multidisciplinary medical practice in Wodonga, Victoria. She is involved in education for evidence-based best practice in peripheral vascular screening.

Podiatric screening for peripheral artery disease (PAD) provides a non-invasive clinical assessment opportunity to flag the likelihood of vessel disease, a disease that is likely to exist in more than one vascular bed.

People at risk are putting their feet in podiatrists’ hands. However, screening for PAD is often conducted only on people with symptoms or visual signs.

This needs to change.

“Although some people are symptomatic, in which case their disease has usually been diagnosed, an important proportion of people with CVD are asymptomatic, and these people often remain undiagnosed.”

First of all, PAD screening has been recommended by international guidelines as follows:

For people with known vascular disease risk factors, such as diabetes, high-risk ethnicity, smoking history, an abnormal pulse, hypertension, elevated cholesterol, existing cardiovascular disease or a history of vascular surgery.
There is current recommendation not to perform PAD screening in asymptomatic people using the ankle-brachial index (ABI). However doppler, toe pressure and toe-brachial index (TBI) screening are useful.
For people over 65 or 70 years of age.
Frequency of screening depends on risk level and clinical imperatives but is advised at least annually. People with diabetes and neuropathy are recommended to have a neurovascular screening every three to six months, or every one to three months if they have a history of foot ulcers.

Why is PAD important?

Because “Life is Why”. Identifying PAD can make life and limb-saving differences to people’s lives, since podiatrists care for people with various levels of cardiovascular disease (CVD).

Although some people are symptomatic, in which case their disease has usually been diagnosed, an important proportion of people with CVD are asymptomatic, and these people often remain undiagnosed.

Why does PAD so often go undiagnosed?

Historically, classification of PAD relied on visual signs and symptoms, especially intermittent claudication and loss of pulses. However 66% of people with PAD have palpable pulses.
PAD is symptomatic in only about 25% of people with the disease.
You can't actually see PAD unless there is tissue damage that occurs in advanced disease.
People can have feet that look and feel absolutely normal, yet have clinically significant PAD with operable lower-limb stenoses.
Only a minor percentage of people with PAD have claudication - 11% in an elderly population.

We can potentially save lives

Ischaemic heart disease (IHD) and stroke are the most common manifestations of PAD, and these were the top two causes of death in 2019. Prior to the COVID pandemic, IHD was responsible for the largest increase in deaths over the last two decades.

A majority of these people with IHD will be developing asymptomatic vascular disease in their peripheral arteries, with a strong predilection for the vessels in the lower limb, before they are diagnosed with cardiac or brain vessel disease.

Most importantly, up to one quarter of people who die from a heart attack or stroke had no known CVD risk factors prior to their death and people with no previously known risk factors have higher fatality rates in the days after their heart attacks.

“A majority of these people with IHD will be developing asymptomatic vascular disease in their peripheral arteries, with a strong predilection for the vessels in the lower limb, before they are diagnosed with cardiac or brain vessel disease.”

"The handheld doppler ultrasound test can save lives by flagging PAD as an indicator of the risk of cardiovascular disease in cases where vessel disease is otherwise silent."

"The combination of more than one valid vascular test gives the most reliable and useful results."

Early identification provides opportunities for risk reduction

Peripheral artery disease is present in most people with cardiovascular disease. The presence of PAD is a marker of underlying atherosclerotic disease affecting other vascular beds. In fact, 61% of people with any vascular disease of the heart or brain also have PAD.

Types of vascular disease

Vascular disease usually manifests in several conditions concurrently.

For example:

Cerebrovascular disease (stroke blockage or an aneurysm - CVA)
Coronary artery disease (myocardial infarction - MI)
Carotid artery disease (strokes- CVA)
Renal artery stenosis (chronic kidney disease - CKD)
Visceral artery disease (e.g.ischaemia of intestines, liver or spleen)
Ophthalmic artery disease (retinal hemorrhages)
PAD (predominantly affecting the lower limb- chronic or acute ischaemia).

Why does peripheral artery disease remain under-recognised and under-treated?

This has been due to a combination of barriers to screening, including knowledge deficit, and lack of human and clinical resources.

The main test historically used for PAD screening, the ankle brachial index (ABI), has significant inherent problems just now being recognised. With advancing atherosclerotic disease, the likelihood of false negatives from the ABI increases.

Emerging evidence

Dr Peta Tehan and a team at Newcastle University, published research in 2018 showing that a monophasic handheld doppler tracing is indicative of PAD, with accuracy comparable to a lower-limb angiogram. Angiogram is considered the reference test most accurate for indicating vessel disease, but because it is invasive and expensive, it's reserved for surgical planning.

The handheld doppler ultrasound test can save lives by flagging PAD as an indicator of the risk of cardiovascular disease in cases where vessel disease is otherwise silent.

The combination of more than one valid vascular test gives the most reliable and useful results. Toe pressure is a meaningful predictor of non-healing as recommended by guidelines of the Society for Vascular Surgery. The toe-brachial index (TBI) shows promise as an indicator of PAD.

Test your PAD knowledge

Question 1. Which of these statements are true about the prevalence of PAD at 60 years of age?

A) At least 10 - 15% in the general population

B) At least 30% in at-risk groups

C) Rises exponentially with age and increasing disease

D) All of the above

Question 2. Asymptomatic PAD is less common than symptomatic PAD.

True or false?

Question 3. Morbidity and mortality are greater when PAD is symptomatic 11.

True or false?

Answers: 1. D, 2. False, 3. False

“Australian cricket legend, Dean Jones died suddenly at 59 years of a stroke, initially reported as a heart attack, seemingly without previously appreciated cardiovascular risk factors” (SMH)

Time for change

By giving space for cardiovascular issues in this digital format of STRIDE, the APodA is raising awareness and preparing for systemic change where podiatrists have an increasing role as leaders in clinical diagnosis of PAD.