Cutting off blood supply therapeutically
In these embolization procedures, the interventional team will first create an image of the distorted veins using various forms of angiography. Then the specialists will introduce a catheter (small plastic tube) into a primary artery and advance it to the area to which there is a need to cut off blood supply. The specialists inject a granulized or particulate material that congeals and hardens, thus blocking blood flow. Or, they may insert a metallic coil through the catheter that remains in place so that the body will form a blood clot around the coil and block off the area. The materials used may depend on the size and type of area to be closed and on whether the occlusion is intended to be temporary or permanent.
This transcatheter embolization has a variety of applications, including most importantly:
• fibroid masses. One use of the technique that has received significant attention recently is in uterine artery embolization, where the purpose is to kill or shrink fibroid masses in the uterus. The treatment addresses pelvic pain, excessive bleeding, and other symptoms of abnormalities in the uterus.
• aneurysms. Specialists also use embolization to block aneurysms (areas in arteries that are weakened and bulging) in different locations of the body. The treatment seeks to seal off the aneurytic bulge, as well as the neck of the bulge within the artery. Interventionalists can permanently deploy a tiny coil of soft-metal filament in the aneurysm, providing a much-preferable alternative to surgery to remove the aneurysm. This the procedure has allowed treatment of aneurysms that were previously considered in operable. The procedure reduces much of the danger presented by aneurysms and can sometimes be used to treat aneurysms that have already ruptured. (Note that in recent years, in the hands of neurosurgeons - or at some centers, interventional neuroradiologists - endovascular coil embolization has become a standard treatment for patients who have a brain aneurysm but who are at high risk for complications from a surgical repair of the aneurysm.)
• tumors. The technique can also be used to reduce or destroy cancerous tumors. For tumor control, embolization is a more likely approach if the tumor is difficult to remove surgically, due to its location. This is particularly relevant for liver tumors or for certain tumors with extensive blood supply such as those resulting from kidney cancer. The cancer team will sometimes use the step to reduce tumors prior to, and make them more amenable to, surgery.
In a tumor embolization procedure, the cancer team can also deliver chemotherapeutic drugs through the catheter to more directly expose the tumor to these cancer-killing agents, and decrease the amount of drug circulated systemwide in the body. This treatment is called chemoembolization. Tumor embolization can be a highly effective step for control of pain resulting from tumor growth, and can help some patients avoid powerful, opiate pain-killing drugs.
• arteriovenous malformations (AVMs). Included among vascular problems treated with embolization are arteriovenous malformations (AVMs), an unusual condition in which an artery and vein have an abnormal connection, causing leaking and mixing of blood between arterial and venous supplies
• bleeding. Embolization is an important option in treating internal bleeding and is used for this application more often than for any other purpose. Radiologists employ the approach to stop or reduce gastrointestinal bleeding in cases where ulcers bleed into the stomach or intestines, and for blood-vessel ruptures in or around the digestive tract (mesenteric bleeding). The radiologic specialists also use embolization commonly interventional treatments for trauma, where frequently the technique is essential to stop bleeding into the abdomen or pelvis in individuals who have been injured in automobile accidents. Finally, the IR team may also apply the treatment to stop severe postpartum bleeding and even to stop severe nose bleeds.
• enlargement. Splenic embolization is a newer technique developed as an alternative to splenectomy (open surgical removal of all or part of the spleen). Splenic embolization is designed primarily for patients who are unlikely to tolerate an open surgical procedure well but who suffer from enlarged spleens. This type of embolization involves introducing a catheter and advancing it to the splenic artery to partially plug or block this artery that supplies blood to the spleen. The step shrinks the spleen. Substances injected during this procedure to create the blockage can include polyvinyl alcohol foam, polystyrene, or silicone.
For an embolization procedure, the IR team will typically sedate the patient and insert the catheter into the femoral artery or vein, through a small incision in the groin (although vessels in the arm or neck may also be used). With the imaging guidance, they painlessly advance the catheter to the site of the vein or artery that needs to be closed off.
Depending on the problem and the objective of the embolization, the team may inject gelfoams, glues, or scarring agents (sclerosant), as alternatives to particles or coils, as the embolizing agent. Also, the specialists will sometimes need to repeat the embolization procedure at intervals to fully plug vessels. (For malformations that consist simply of an abnormal cluster of blood vessels or lymph material, the specialists can sometimes inject a scarring agent with a needle placed through the skin, to clot and shrink the malformation, in a treatment called sclerotherapy.)
Embolization is an effective intervention for stopping blood flow to targeted areas. It results in minimal blood loss, and allows most patients to avoid general anesthesia. In addition, unless their condition has caused bleeding, patients who undergo embolization generally have a short hospital stay of approximately one night and will resume normal activities within a week. A few weeks or months may be needed to fully determine whether the embolization has achieved its aim of controlling symptoms (including pain and other tumor-related complications), bleeding, or growths.
The IR team will usually follow up the procedure with additional angiography or other imaging to evaluate the positioning and results of the embolization. The success rates of embolization are high, and the procedure is dramatically less invasive than open surgery, making recovery much quicker and easier.