Peripheral Arterial Disease: A Guide For GPs

Peripheral Arterial Disease (PAD) is a perilous condition silently affecting millions worldwide. [1] This blog is designed as a short guide for general practitioners and other medical professionals. It contains global and some local statistics of PAD prevalence, presents PAD risk groups, and discusses the compounding effect of smoking and multiple risk factors. It also features basic information on the Ankle-Brachial Index (ABI) as a diagnostic tool, explaining its reference scale and pulse waveform recording, as well as cases when the Toe-Brachial Index is used.

In this blog you will learn:

What is PAD and how frequent is it?

Peripheral Arterial Disease (PAD) is atherosclerosis (plaque buildup) in the arteries supplying the legs. [1] It is a frequent but underdiagnosed condition, often with severe consequences. They include death, stroke, coronary heart disease, amputations, dementia and cognitive impairment.

Here is some global and local information about its prevalence. PAD affects:

more than 230 million adults worldwide, [1]
6 million (9 %) of the UK population, [2]
4.5 million (5.3%) of the population in Germany, [3]
4-8 million (6-12%) of the population in France, [4]
3-5 million (5-8%) of the population in Italy, [5]
in Slovenia, 2000-3000 patients with PAD are discovered on a yearly basis. [6]

Why screen for PAD?

The latest AHA Scientific Statement recommends that PAD screening with ABI is urgently implemented in high-risk populations. TBI should be employed if suspecting medial artery calcification, e.g. in cases of chronic kidney disease (CKD) or diabetes. [1]

Effect of smoking

Smoking is a major risk factor in developing PAD. Smokers are at 2x greater risk of PAD compared to non-smokers. With former smokers, it takes up to 30 years for the PAD risk to reach the non-smoker level. [1]

Effect of combination of risk factors

The duration of hypercholesterolemia and diabetes, the severity of hypertension, and cumulative intensity of smoking show graded relationships with PAD risk. [7]

70% of patients with PAD do not experience symptoms and are thus not diagnosed. The TASC II consensus document recommends Ankle-Brachial Index measurement for all PAD risk groups. [8]

Ankle-Brachial Index. A simple tool in detecting PAD

The Ankle-Brachial Index (ABI) is an effective comparison of blood pressure in the legs and the arms. It is non-invasive and painless. Using MESI mTABLET ABI, the procedure is quick and simple. Therefore, the test can be implemented routinely in both primary and specialised care. The ABI test is extremely important for two reasons:

It is a reliable predictor of PAD.
Due to a high co-occurrence of PAD with other diseases, diagnosed patients have a great chance of early diagnosis of the other diseases such as:
coronary artery disease (CAD) or cerebrovascular disease (CVD): 32% [9],

renal insufficiency (RI): 39.7% [10],
diabetes: 49.7% [11],
metabolic syndrome: 58% [12]/63% (45+) [13],
hypertension: 35–55% [14],
hypercholesterolemia: 60% [15].

ABI pulse waveform recording and ABI reference scale

Let’s take a look at normal and abnormal results of the ABI pulse waveform recording on the MESI mTABLET ABI – a digital, automated ABI-measuring device.

Normal result

The oscillation graph forms a clear lemon shape. This means that the arteries are elastic and that they responded to being briefly compressed by the cuff. The pulse waveforms have these characteristics (cf. the illustration):

A rapid rise in the upstroke during systole
A very sharp peak
A gradual downstroke
A presence of dichrotic notch

Abnormal result

A flattened pulsewave recording or one without the typical lemon shape is an indicator of severe PAD.

The absence of the pulsations caused by occlusions in the artery makes it impossible to calculate the ankle pressures. Instead of the ABI value, the device will display a “PAD” result.

The illustration shows a flattened pulsewave recording.

ABI reference scale

ESC Guidelines state the following recommendations in connection with ABI measuring [16]:

Measurement of the ABI is indicated as a first-line non-invasive test for screening and diagnosis of LEAD (Lower-Extremity Artery Disease).
In the case of incompressible ankle arteries or ABI > 1.40, alternative methods such as the Toe-Brachial Index, Doppler waveform analysis or pulse volume recording are indicated.

Toe-Brachial Index

The Toe-Brachial Index (TBI) is a comparison of blood pressure in the toes and the arms. It is used in diagnosing PAD:

when the ABI measurement cannot be interpreted or is inadequate,
with non-compressible arteries in the legs (diabetes, insufficiency-related calcification),
in patients with excruciating pain in the lower extremities,
in end-stage renal disease,
in patients undergoing dialysis,
in very advanced age,
and/or in patients with lymphedema.