Angiography/Angioplasty/Stenting/Thrombolysis   Interventional procedures

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Vascular Imaging:
Aortogram and Runoff, Abdominal arteriogram, Angiogram, arteriogram: 
Indications:

Lower extremity claudication is the medical term used to describe pain in the calf muscle after walking a short distance. The pain is caused by narrowed blood vessels and restricted blood flow to the calf and leg muscles. Ischemia or reduced blood flow to the legs muscles is similar to coronary ischemia and angina of the heart except that the process involves different arteries to the legs. In reality, atherosclerosis is a systemic disease process involving the whole vascular tree, so if one area is involved, there is usually involvement in other areas as well. The image at left shows the aortic bifurcation. Atherosclerotic disease of the body preferentially involves only a few key areas. Carotid arteries, at the carotid bifurcations. Abdominal aorta, iliac arteries, superficial femoral arteries, renal arteries, and mesenteric arteries. Coronary arteries (the coronary arteries are studied by the Cardiologist because of the risk of cardiac arrhythmia (heart stopping) during the angiogram.) The other areas of the vascular tree are studied by the vascular interventional radiologist. Make sure your radiologist is board certified in interventional radiology by the American Board of Radiology.

Advanced cases of peripheral vascular disease will have symptoms such as resting pain in the extremity, ulcerations, gangrene etc.

Procedure:

The angiogram is an xray imaging test which takes xray pictures of the arteries of the body. Normally, arteries do not visualize on a plain x-ray. They are made visible by the intra-arterial injection of iodinated contrast material. This is the same contrast used for the IVP and CAT scan procedures (see above). The iodinated contrast appears white on the black x-ray film because of its high atomic density.

First, the patient is placed on the imaging table in the Interventional Radiology Room and then sedated with a narcotic and anti-anxiety drug. Currently most centers use a combination of Versed (valium-like drug) and Sublimaze (short acting narcotic type drug), although any similar regimen works just as well. Because of the risk of respiratory depression (stopping breathing) associated with these drugs, the patient’s blood oxygen saturation is monitored in real time with a Pulse Oximeter by the Interventional Radiology Nurse who remains in attendance during the procedure. The Pulse Oximeter is la little gadget that looks like a clothes-pin which fits over the finger and fingernail and reads the "redness level" of the fingernail capillary bed as blood oxygen saturation. It also records the pulse rate. There is also a blood pressure cuff on your arm and machine readout of blood pressure during the procedure. The cuff inflates every couple of minutes and displays the new blood pressure on a digital readout.

The sedation cocktail also causes amnesia so most patients remember very little about the actual procedure.

Procedure details:

The femoral artery is punctured with a Seldinger Needle. This is a special needle, which allows a J-wire to be advanced into the artery. Once the wire is in the artery, a thin flexible rubber/plastic sheath is advanced over the wire into the vessel. Through the sheath, which provides easy access to the inner lumen of the femoral artery, a 5 French pigtail catheter is advanced into the aorta under flouroscopic observation. A test injection of iodinated contrast with manual syringe injection under flouroscopic observation confirms good placement of the catheter. Then, a Digital Subtraction Aortogram is done.

A Power injector is connected to the catheter, iodinated contrast injected into the aorta, and during the contrast injection, a series of xray pictures are taken at a rate of 3 per second. This series of video images at 3 frames per second is saved on a computer hard disk for later review and print out. The images may be digitally subtracted to make the vessels clearer to the viewer.

Next, the lower extremity vessels are imaged with a long film changer. The patient is moved down to the long film changer table and a larger bolus of iodinated contrast injected into the aorta at the bifurcation and individual long x-rays of the legs all the way to the toes are taken every 5 seconds or so.

After this, the films are reviewed and decision made by the Interventional Radiologist in consultation with the vascular surgeon whether to do anything further by way of treatment (angioplasty/stent/thrombolytic therapy) or whether to terminate the procedure. See example of digital subtraction distal aorta and iliac bifurcation .

ANGIOPLASTY PROCEDURE:

For certain relatively short stenotic lesions (narrowed segments of the vessel) which restrict blood flow, angioplasty is an ideal treatment. Newer guide wires and angioplasty balloons have been developed which make angioplasty technically easier to more successful. The guide wire is advanced across the stenosis, an angioplasty balloon catheter advanced to the narrowed lesion, and the balloon inflated under flouroscopic observation.

If all goes well, the vessel diameter is restored to normal and good, strong blood flow is restored to the extremity.

Risks and complications: Angioplasty is a controlled stretching of the wall of the vessel and always involves some form of damage to the artery wall. Because the vessels undergoing angioplasty are usually very diseased to begin with, there is a risk that they will be made worse by the angioplsty. The inner layer of the vessel may rupture and may form a flap, which obstructs flow. This is called intimal dissection. If this happens, the vessel lumen can be restored with a metal stent.

Vascular Stenting:

At present, there are many types of stents for arteries such as the Palmaz expandable stent (stainless steel) and the Schneider self-expanding Wall-stent. They are both quite easy to deploy and both do a good job of expanding the diameter of the vessel and keeping the vessel open. They are also both good at treating intimal dissection (see above).

At present, stents can be used in the renal arteries, aorta, iliac arteries, femoral arteries. They are not recommended, yet, for superficial femoral arteries or in the carotid arteries unless part of an approved research study.

Thrombolytic Agents: The most commonly used agent is called TPA. Urokinase has been pulled off the shelf by the FDA.

TPA is a chemical agent which has the ability to dissolve blood clots. This agent can be delivered intra-arterially through a small caliber catheter or a hollow wire imbedded directly in the clot obstructing the vessel. After about 24 to 48 hours of continuous infusion, the clot usually dissolves and flow is restored. After flow is restored any underlying stenosis in the vessel can be treated with balloon angioplasty or stent placement.

Risks of thrombolytic therapy: Major risk is that of bleeding from the puncture site or occult internal bleeding.

To see a case of vascular stenting to relieve the SVC syndrome click here: SVC Stent Case.

Carotid Angiography

Carotid artery stenosis may cause TIA's (transient ischemic events) with momentary loss of strength in an arm or leg or transient visual changes. This is sort of a mini-stroke. Complete occlusion of the internal carotid artery may cause a stroke because of lack of blood flow and oxygen to the brain.

Severe stenosis of internal carotid artery

This is an angiogram study of the Carotid arteries located in the neck. Stenosis of the Carotid artery occurrs typically at the proximal internal carotid artery at its origin (see example image above). This can be detected by color flow doppler ultrasound as the first screening test. If the ultrasound is abnormal, the patient will then proceed to carotid angiogram. If the carotid angiogram shows a severe stenosis, then treatment is usually surgical carotid endarterectomy, a removal of the atherosclerotic plaque which restores blood flow to the brain.