Chapter 3 – THE PROBLEMS OF BLOOD CIRCULATION IN THE DIABETIC FOOT.

Obliterative Arteriosclerosis (ASO) describes a slow, chronic occlusion of arteries caused by arteriosclerotic plaques—abnormal hardening and thickening of the artery walls. ASO affects large and medium-sized arteries, including the common iliac arteries in the pelvic area, the femoral artery above the knee, the popliteal artery, and the tibial artery behind the knee.

In diabetic patients, blood circulation issues are compounded by microangiopathy, a condition affecting the small arteries and capillaries of the foot, where the blood vessel walls thicken. This combination makes circulation problems in diabetic feet both more severe and more common.

Risk factors for arteriosclerosis are well established and include cigarette smoking, high blood pressure, high blood cholesterol, and diabetes. Occlusions in the arteries above the pelvis, such as in the common iliac arteries, can lead to sexual impotence and thigh or leg cramps during walking. In contrast, occlusions of the popliteal and tibial arteries are more frequently seen in diabetic patients. The progression of arterial occlusion can be rapid, moderate, or slow; when it is slow, collateral arteries may develop at the site of the blockage, potentially resulting in only mild or even absent symptoms.

When there is a rapid occlusion, it is usually due to an arterial embolism—a small blood clot that travels within the artery—indicating advanced arteriosclerosis. A sudden development of gangrene can be the result of such an embolism. Additionally, if you have a heart problem combined with diabetes, your heart may pump less blood, further reducing circulation to the foot.

There are several signs and symptoms that indicate circulation problems in a diabetic foot. For example, when the foot is raised above the level of the heart, the toes may turn pale (See Fig. 3-1), which is a common indicator of poor blood flow.

But as soon as you stand up, the toes may turn dark and bluish. This color change is characteristic of arterial problems. The skin on the foot and leg may appear smooth, shiny, and paper-thin, while the toenails can become brittle and yellowish due to a lack of blood circulation. The foot typically feels cold and wet, and the pulses in the foot are often absent. Occasionally, pulses can be felt when the foot is at rest, but they tend to disappear during or after exercise. If one foot is colder than the other, this is more concerning than if both feet are equally cold. Additionally, hair loss on the toes, top of the foot, and lower leg may occur, and the thigh and leg muscles can shrink due to insufficient blood supply. In some cases, you may experience intermittent claudication, which is described as pain and cramping in the thigh and/or leg muscles after walking a certain distance (See Fig. 3-4).

Pain and cramps may be temporarily relieved by stopping walking and massaging the leg. However, as the disease progresses, the distance you can walk without experiencing cramps and pain decreases significantly. In its most severe form, you might even feel pain at night in the buttock, thigh, or calf—pain that is relieved when you get out of bed and walk around. This pattern indicates that your leg is congested with blood, increasing the gravitational stress when standing. At this advanced stage, even minimal trauma to the foot can put you at the highest risk for gangrene. Furthermore, in this advanced stage of the disease, a foot ulcer may develop, and these ulcers might show no signs of bleeding, which further complicates the condition and increases the risk of severe complications.

This is called an ischemic ulcer, and it can be very painful. However, in diabetics the ulcer might be painless due to the presence of neuropathy.

Symptoms of arterial disease can alert an experienced podiatrist to perform appropriate diagnostic tests. One simple yet specific test is measuring capillary filling time with the patient lying down, which helps gauge the extent of arterial perfusion in the toes. Your doctor may initially order an ultrasound test of your lower extremities to assess blood flow. This measurement can be taken both with the patient standing and after exercise. An experienced physician can discern the different sounds produced by blood flow during an ultrasound examination. The ultrasound also measures blood pressure in the arm and foot—a crucial parameter for proper wound healing. Unfortunately, if there are calcified (hardened) arteries in the diabetic foot, the ultrasound may inaccurately measure blood pressure, making the test unreliable. In fact, the diabetic foot can sometimes be deceptive even to an experienced doctor, because circulation problems in these feet are often misinterpreted. The foot may feel warm, the toes might not turn pale when elevated, and pulses may still be present despite significant underlying arterial disease.

Nowadays, contrast angiography enables clinicians to directly visualize the lumen of the artery. More recently, Magnetic Resonance Angiography has gained significant popularity among vascular surgeons as a non-invasive diagnostic tool. Additionally, 3D CT scanning is also proving useful for detailed evaluation of vascular structures.

Once you have been diagnosed with arterial disease in your feet, you need to understand the consequences of presenting this significant problem. The foot amputation rate in diabetic people is "fifteen times higher" than in the non-diabetic population. The initial lesion of the skin, be it a blister or a callus, occurs in the painless neuropathic foot. However, there is an arterial circulatory problem that hinders these foot injuries, so that they may not heal. The impaired circulation stimulates necrosis of the tissue around the skin lesion. Bacteria thrive in a rich environment of diabetic foot necrotic tissue where the arterial supply is impaired. The decrease in blood flow to the foot prevents the arrival of antibiotics as well as the cells that fight infection which are called leukocytes. Also, the decrease in oxygen to the contagious site promotes the growth of bacteria that do not require oxygen, and which are very destructive to the foot. Neuropathy as well as damaged blood circulation and infection make diabetic people very susceptible to a crisis that will lead to foot amputation.

Diabetic foot arterial disease is a lifelong condition that requires you to make significant lifestyle changes. You need to quit smoking, lower your cholesterol and blood pressure, and manage your diabetes intensively. Regular exercise is crucial because it promotes the formation of collateral blood circulation, which may help prevent the need for surgical treatments or even amputation. Aim to exercise daily—walk until you begin to feel a cramp in your leg muscles or pain, then stop, and repeat this three to four times a day.

Daily foot care is essential. Inspect your feet every day for signs of infection or cuts, and wash them with warm water and a mild soap. Have your toenails and calluses checked regularly by your doctor or podiatrist. Wear only appropriate shoes (see Chapter 10) and use orthotic insoles if you have neuropathy and circulation problems. These insoles are important because they redistribute pressure away from ulcers on the sole of the foot, promoting healing.

Additionally, fungal infections can further compromise your already damaged foot by leading to bacterial infections and gangrene. Remember that even small infections— such as those caused by ingrown toenails —can progress to ulcers, become gangrenous, and ultimately require amputation. Taking these proactive steps is essential for preventing severe complications.

There are several surgical procedures that can benefit people with severe arterial occlusive disease. If you experience foot pain at rest, non-healing foot ulcers, frank gangrene, or signs of impending gangrene, discuss surgical options with your doctor. Some surgeries can prevent a major leg amputation. Vascular surgeons, for instance, can perform revascularization procedures to improve blood flow to the foot or leg, potentially limiting the level of any necessary amputation.

However, not everyone is a candidate for vascular reconstructive surgery. A vascular surgeon can evaluate your condition—often using an arteriogram—to determine if you are a suitable candidate. In cases where occlusion affects the small arteries of the foot, amputation of one or several toes might be indicated. With large artery occlusions, such as in ASO, surgery may be unavoidable. In such instances, a below-the-knee amputation is preferable to an above-the-knee amputation (See Fig. 13) because it carries a lower risk and allows for easier rehabilitation.

It is extremely important to recognize the early signs of circulation problems in your feet. Your commitment to seeking prompt medical attention and making necessary lifestyle changes—such as quitting smoking, managing your blood sugar, and exercising regularly—can significantly reduce your risk of severe complications. By taking proactive steps, you can help prevent yourself from becoming just another statistic.