Diagnosis of peripheral arterial disease
Synonyms
Diagnosis of PAD, examination of peripheral arterial occlusive disease, Ratschow positioning test
diagnosis
The doctor asks at the beginning Medical history (Anamnese). The walking distance that can be managed without pain is particularly important. This is of particular importance for the staging of PAOD (see staging according to Fontaine-Ratschow).
Research will also be conducted into risk factors, especially smoking, Diabetes (Diabetes mellitus), Lipid metabolism disorders and others.
Then the physical examination. It starts with the inspection, i.e. assessing the affected extremity. Here, skin color (pale in the case of PAD), temperature (cold in the case of PAD), tissue loss, black discolouration and ulcers are checked. We also look for other signs of a nutritional disorder (trophic disorder) of the extremity, such as Muscle wasting (atrophy), impaired nail growth or hardening (fibrosis).
The doctor will then try to feel the various pulses (palpation), as this allows the location of the constriction to be narrowed down. These are weaker or not at all palpable in the affected area. For the leg these are 4 important ones:
- Groin pulse (Femoral artery)
- Pulse in the hollow of the knee (popliteal artery)
- Pulse on the back of the foot (A. dorsalis pedis)
- Pulse behind the medial malleolus (posterior tibial artery)
Even with that stethoscope a flow noise can be heard at the affected area, as the blood has to pass through a constriction at increased pressure. (Listening with the stethoscope: auscultation).
Storage sample according to Ratschow
Since the pain often occurs after lifting the leg (increased oxygen demand due to muscle work), the Ratschow position test can also be carried out. Here the patient has to move their feet with their legs upright until symptoms occur. The affected leg becomes paler. If the legs are now allowed to hang down again, a reddening of the leg will appear after a few seconds due to the increased blood flow. Peripheral arterial occlusive disease (PAD) takes longer to show up.
As the last procedure without further technical aids, the blood pressure is determined on both the arms and the legs. If the blood pressure of the arms is higher than that of the legs, this is an indication of a narrowing in the area of the legs.
Normally the pressure is higher in the legs, as they are lower and thus the blood above them also pushes downwards.
Another examination to be able to objectively determine the extent to which the impairment exists is the walking test. A treadmill is used to determine how long the pain-free walking distance is (important for the subdivision in stage II, see staging according to Fontaine-Ratschow).
The most important examination method is Doppler sonography, an ultrasound examination. It is non-invasive (no intervention in the body) and can be carried out quickly. This makes it possible to determine the flow velocity of the blood. Above the constriction, this is greatly increased, since the same volume of blood has to flow through a smaller inner diameter (lumen) here. This examination can also be used to detect certain changes behind the affected area.
Read more on the topic: Doppler sonography
Radiological examinations can be carried out to obtain more precise information about the location, length and extent of the narrowing. These include e.g. (3D) MRI angiography (a magnetic resonance tomographic examination), CT angiography (a computed tomography, a special X-ray procedure) or digital subtraction angiography (DSA, also a special X-ray procedure).
MRI is not possible in patients with cardiac pacemakers or metallic implants.
All of these examinations are carried out with the help of contrast media.
However, since there is always a certain risk of the vessel becoming completely closed, these examinations are usually only carried out if there are reasons for interventional therapy. Either in the form of a catheter procedure or surgery (see PAD therapy).
It is also important to carry out further examinations to determine whether the arteries supplying the brain or the coronary arteries are involved.
