Angiography

Angiography is a radiographic procedure that employs x-rays of the blood vessels in the body to assist in diagnosing and treating a variety of ailments. The x-ray image, or angiogram, allows diagnosis of pathologies of the blood vessels such as blockages, stenosis (narrowing of the vessel), and other aberrations so that they can be treated. Angiography can be purely investigative,rift gold but it is commonly employed in combination with minimally invasive surgery or catheterization. In the angiography procedure, a venous ‘‘contrast,’’ or dye, is administered orally, anally, or by intravenous injection. This dye is a radiopaque substance that highlights the blood vessels in the x-ray.

Magnetic resonance angiography (MRA) does not rely on radioactive dye; rather it employs a specific sequence of radio waves to create the angiogram. The MRA is able to provide a detailed map of the patient’s vasculature without an enhancer, although enhancers such as the rare earth element gadolinium are sometimes used to make the images clearer and bolder. In therapeutic or interventional angiography, the possible treatment runs from surgery to less invasive processes such as angioplasty or catheterization. In angioplasty, a catheter containing a small balloon is guided through the blood vessels to the site of the obstruction. Once in place, the balloon is inflated in order to expand the constricted area of the vessel. The catheter can also be used to guide into place surgical ‘‘stents,’’ cylindrical mesh-like supports that keep the vessel open to the desired width. Over one million angioplasty procedures were performed in the U.S. in 2000 to prevent or treat myocardial infarction (heart attack).

Rudimentary angiography was developed not long after the x-ray came into clinical use. In 1896 in Vienna, Eduard Haschek and Otto Lindenthal took x-rays of the blood vessels in an amputated hand injected with a radiopaque substance. The radiopaque contrast agent of choice has changed over time, owing in part to the high toxicity of the earliest agents used. Common formulations of contrast agents used today include various acetrizoic acids, diatrizoic acids, iodamides, and methanesulfonic acids.

Angiography is employed today in a number of clinical situations. The most common procedures performed are cerebral angiography, thoracic aortography, pulmonary and bronchial arteriography, coronary arteriography, and angiography of the extremities. In celial and mesenteric angiography, these arteries in the abdomen are examined to diagnose gastrointestinal bleeding, aneurysm, or ischemia. In cerebral angiography the blood vessels of the brain are investigated in order to locate and treat of blood clots, aneurysms, tumors, and migraines. In coronary angiography the coronary arteries are investigated to detect vascular diseases such as heart disease, heart attack, and acute stroke. Renal angiography is of value in diagnosing kidney disease and renal failure. In the latter case, the physician uses hemodialysis catheters to divert blood from the neck and filter it through a hemodialysis machine. One problem with kidney angiography is that the contrast agent can be harmful to the kidneys if the patient already suffers from renal ailments. In ocular angiography either fluorescein or indocyanine green contrast helps to view various problems in the eye such as retinal failure.

Complications surrounding angiographic procedures can arise either from reactions to the contrast agent or from problems with the performance of the catheterization or surgery. Reactions to the contrast agent are generally mild, such as nausea, but serious allergic reactions do occasionally occur. Renal damage can occur regardless of previous problems because of the mild toxicity of most opaque media contrasts. Some contrasts have also caused minor drops in blood pressure and vasodilatation of the arteries. When a catheter is placed in the body, blood clots can form and block the vessel or a small particle can break loose and lead to embolization, a potentially deadly complication. Catheters can also tear or puncture blood vessels causing internal bleeding rift gold and an exacerbation of the already existing problem. Hematomas and hemorrhages may occur if there are any complications in the catheterization process.

As with other medical tests and procedures, the risks of angiography are generally outweighed by the benefits, as the angiogram provides specific and detailed clinical information that is invaluable in clinical diagnosis and intervention.