What is Peripheral Vascular Disease?
Peripheral vascular disease restricts the flow of blood through the vessels throughout the body. These vessels, which carry oxygen and other nutrients to vital organs and tissues, are most often caused by atherosclerosis (also called hardening of the arteries), a progressive disease process caused when plaque (composed of fat, cholesterol, and other substances) is deposited on the interior wall of the artery.
As the artery narrows (called stenosis) over time, blood flow through the artery is reduced or stopped. Plaque commonly forms in the iliac arteries (lower abdomen) and the femoral and popliteal arteries (legs).
When arteries become blocked, they cannot supply an adequate amount of oxygen-rich blood to the muscles causing severe pain or even death to the tissues - gangrene - in the affected area.
When symptoms appear, a general physical examination is the first step of the evaluation. Other tests will help the doctor determine whether the patient might benefit from peripheral vascular treatment (intervention).
The next step in the evaluation may involve the use of an arteriogram. This test uses an injected dye and x-ray equipment that shows the arteries and extent of the blockage.
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Many techniques can be used to increase the flow of blood through the arteries. The latest interventions for treating vascular disease can be done quickly. Most patients can expect a short hospital stay and early return to normal activities. Devices now available include atherectomy, balloon catheters, stents, and endoluminal grafts (ELGs). These new technologies remove or displace the plaque that blocks blood flow to the lower extremity. During these procedures, dye is injected at certain times and x-rays are taken to determine whether the artery has been opened adequately; if it hasn't, the treatment will be continued or repeated.
If the blockage is composed of very hard, calcified material, it may be resistant to any of these interventions. Bypass or detour of the blockage using a vein or synthetic (man-made) graft may then be necessary.
If blood clots are the suspected cause of the blockage, strong, clot-busting drugs called thrombolytics are used first. A catheter is guided to the site of the blockage in the artery. The thrombolytic drug is infused through the catheter until the clot is dissolved. Periodic x-rays with dye are taken to monitor this treatment. Depending on the progress, the catheter may be advanced so the drug is deposited directly on the clot.
Balloon angioplasty is now the most common method used for opening an obstructed artery. A wire is first passed through the narrowed part of the artery. A deflated balloon, attached to a catheter (tube), is passed along the wire through the vessel to the area of narrowing.
The balloon is then inflated and deflated, sometimes more than once and often in more than one location. This flattens the plaque against the vessel wall, increasing the size of the opening in the artery. Balloon angioplasty may be the only treatment needed, or it can be used along with one or more of the other options.
An atherectomy catheter has a small rotating cutter at its tip that either cuts or pulverizes plaque that is blocking an artery. Removing the plaque by this procedure enlarges the arterial opening so blood can flow freely again. Some atherectomy devices are effective in soft plaque, while others are designed for highly calcified plaque (Rotablator). Some can suction the debris from the artery, eliminating any chance that fragments of plaque will be carried by the blood to other parts of the body.
This device may be inserted in the artery in some cases to prevent an artery from closing or re-narrowing during or after a procedure. This tiny, expandable device is made of metal and mounted on a deflated balloon attached to a catheter. When the catheter is in position at the site of the blockage, the balloon is inflated and the stent is expanded. The balloon catheter is then removed, allowing blood to flow through the artery again. The expanded stent, which looks like a rolled piece of fence, remains in place permanently.
Thrombectomy and Embolectomy
Clotted blood can be removed from an artery with a balloon catheter. The deflated balloon, attached to a catheter, is passed into the vessel beyond the clot and inflated. It is then pulled back through the artery, scooping the blood clot along with it.
The surgeon can make an incision in the artery and pull out the plaque that is causing the blockage. The opening in the artery is then closed with sutures. Removal of the plaque by this method is called an endarterectomy. It is most commonly performed in the neck on the carotid arteries leading to the brain to prevent strokes. Recent clinical studies support the use of carotid endarterectomy as an effective means of averting stroke in patients with severe blockages (more than 70%).
Another common site for endarterectomy is the groin area where the deep and superficial arteries divide. Removing the plaque allows other devices to be advanced to blockages lower in the leg.
As a last resort, a narrowed or blocked section of an artery can be detoured or bypassed with grafts. A graft may be synthetic, or it may be a natural vein taken from another part of the body, most often the leg. One end of the graft is attached to an artery above the blocked area, and the other to an artery below the blockage. Blood then travels from the artery above, through the bypass graft, and to the artery below the blockage, where it circulates to the lower part of the leg and foot.
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