Figure 3.1 Arterial System
Atherosclerosis is the commonest cause of arterial disease. Less common causes are thromboembolism, vasculitis, Raynaud’s disease and cold injury (Haslet et al. 1999, Veller 2011).
Atherosclerosis is a local thickening (plaque) of the inner most layer of elastic and muscular arteries (intima), such as the aorta, coronary, cerebral, internal carotid, iliac, femoral and mesenteric arteries. Blood vessels of a diameter of less than 3µm are not affected (Tortora & Derrickson, 2014).
This condition presents as fatty deposits called atheroma, are laid down in the arteries. The flow of blood through the artery can become impaired by the build-up of atheroma.
Figure 3.2 Atherosclerosis
The artery can also become completely blocked by this build up, or from a blood clot forming on the rough surface of the deposits. Smokers are more likely to develop atherosclerosis (Powell, 2010; ASH, 2016).
There are also other risk factors for the development of atherosclerosis, which include;
- Cigarette smoking
- Physical inactivity
- Age 65+
- History of coronary artery disease
- Family history
- Diabetes mellitus
- Oxidative Stress (e.g. Angiotensin II – free radical)
There are a number of clinical conditions caused by atherosclerosis:
|Cerebrovascular disease||Renal artery disease|
|Transient ischaemic attacks||Renal failure|
|Cerebral thrombosis (stroke)||Hypertension|
|Coronary artery disease||Mesenteric artery disease|
|Stable angina||Intestinal angina|
|Thorax & abdomen||Lower limbs|
|Aortic artery disease||Peripheral vascular disease|
|Aortic dissection||Intermittent claudication|
|Aortic aneurysm||Critical limb ischaemia|
|Acute limb ischaemia
These atherosclerosis-derived conditions are caused by the effects of reduced or occluded blood flow to an area of tissue and this results in pain, dysfunction and, at the worst end of the spectrum, tissue death (Ockenden, 2001).
Arterial ulceration (explained further in Module 4) results from a lack of adequate blood supply to adequately perfuse tissues. Atherosclerosis is the reason for reduced blood supply and therefore the commonest cause for arterial ulceration (Moffatt 2001, Wound Source 2019).
Peripheral Vascular Disease (PVD)
The term peripheral arterial disease is widely used to refer to atherosclerotic disease that obstructs the blood supply to the lower limbs (Mohler & Jaff 2008, NHSUK 2019)
A major indicator of PVD is intermittent claudication (IC), described below. The reduced blood flow to the limbs can cause the following physical changes;
- The foot may develop dusky erythema as the blood vessels dilate in an attempt to increase blood supply to the tissues that are oxygen deprived
- Hair loss from the limbs
- Diminished or absent foot pulses
- The reduced skin perfusion that can result in inadequate tissue oxygenation, which will promote the development of arterial ulcers of the leg or foot (Vuolo, 2009).
Ischemic digital toes in patient with peripheral vascular disease.
lschemia can cause reduced blood flow to the lower limb and consequently poor tissue oxygenation, this then leads to the changes seen. Ischemia is a severe condition that can cause tissue damage and result in loss of limbs. This condition will not improve on its own and requires appropriate medical intervention.
Arterial leg ulcer.
They develop as the result of damage to the arteries and a lack of blood flow to tissue, PAD/PVD. Arterial ulcers are often painful and non-healing ulcers may require urgent treatment is to improve the blood supply.
Intermittent Claudication (IC)
Intermittent claudication is an important indicator of PVD. IC is a symptom related to reduced perfusion through an artery caused by atheroma. During exercise the reduced perfusion causes hypoxia in the muscle distal to the site of atheroma and a cramping pain is experienced. This pain is relieved by rest. Pain in the calf (the most common area) or foot, indicates disease of the femoral or popliteal arteries, and pain in the buttocks and upper thighs indicate disease of the aortoiliac arteries (Vuolo, 2009).
It is important to assess the distance a patient can walk prior to the onset of pain, and the ways in which patients find they can relieve the pain. This shows the extent of the patient’s PVD (Vuolu, 2009).
With regular exercise and lifestyle changes IC symptoms can be resolved (Dealey, 2005). Lifestyle changes will depend upon an individual’s circumstances but they include; smoking cessation, weight reduction, control of hyperlipidaemia, eating a healthy diet and foot care.
However if PVD progresses, IC pain may become continuous and prevent the patient from sleeping. At this stage, patients find that the symptoms are relieved when their legs are dependant (not elevated). Therefore they may hang their leg down out of the bed or sleep in a chair to relieve pain. This can progress to chronic critical limb ischaemia (Vuolo, 2009).
Other causes of arterial ulceration include:
- Trauma that interrupts blood flow
- Raynaud’s disease
- Cold injuries such as frostbite
Patients may also develop arterial ulcers due to acute events such as an arterial embolism or severe injury that disrupts blood flow (Moffatt 2001, Veller 2011).
Venous Disease and Venous Leg Ulcers
Figure 3.3 Diagram of Venous System
Blood is pumped back to the heart through the veins by the calf muscles. Venous valves exist to prevent the back flow of blood (vuolo, 2009).
Figure: 3.4 Diagram of a Healthy Calf Pump
Poor valve performance can be caused by congenital or familial defect, damage from a previous deep vein thrombosis (DVT), surgery, pregnancy, varicose veins, injury or a mechanical defect due to a higher obstruction to venous return. Regular ‘chair sleeping’ combined with poor mobility can also significantly impair venous return (Vuolo, 2009).
Diagram 3.5 Diagram showing normal and faulty valves.
The presence of oedema slows down gaseous exchange within the microcirculation, it also results in reduced tissue oxygenation and inadequate toxin removal (EWMA 2016). Eventually, tissue health suffers and skin lesions appear, often without any trauma to the tissues. Patients are often unaware of the problem until they notice staining on their clothing.
Mixed Venous and Arterial Disease
It is very common for a patient to have both arterial and venous vascular problems. A careful assessment of all lower limb wounds must be undertaken by an experienced practitioner to establish the underlying cause because the management of these wounds must address the underlying issues.
Mixed ulcers will be discussed in detail in Module 4, Section 6: Leg Ulcers