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Diagnostic and Interventional Angiography

Angiography is a procedure in which blood vessels (arteries or veins) are injected with a dye that shows up on X-ray. The procedure may be only for diagnostic purposes at which time only X-ray images of the blood vessels are obtained; or the procedure may include treatment. The former procedure is called 'diagnostic angiography' and the later 'interventional angiography'. When an artery is injected, it is called arteriography and venography when a vein is injected. Most commonly the arteries are investigated and only occasionally the veins.

Anatomy

  • When dye is injected into an artery, it first outlines the arteries then passes through the capillaries and into the veins. There are six regions in the body that are frequently subjected to arteriography:
  • Cerebral arteriography involves the study of the arteries that go to the brain (Figure 1) The arteries are visualized from their origin in the aorta (the large artery that comes off the heart) to their entire course in and outside the skull
Figure 1 - Arterial anatomy from the aorta to the arteries of the head. © P. Montelone
  • Thoracic aortography involves the study of the aorta in the chest (Figure 2)
  • Abdominal aortography involves the study of the aorta in the abdomen (Figures 2 and 3)
  • Mesenteric arteriography involves the study of the arteries going to the bowel (Figure 3)
  • Renal arteriography involves the study of the arteries going to the kidneys (Figures 2 and 3)
  • Aortography with lower extremity (leg) run-off involves the study of the lower aorta and arteries of the legs (Figure 4)
  • Arteriography of the upper extremity (arm) is less frequently obtained (Figure 5)
Figure 2 - Anatomy of the aorta and branches. © P. MonteloneFigure 3 - Anatomy of the abdominal aorta and its branches. © P. Montelone
Figure 4 - Arterial anatomy of the lower extremity. © P. MonteloneFigure 5 - Arterial anatomy of the upper extremity. © P. Montelone

Pathology

The most common diseases for which angiography are performed are:

  • Atherosclerosis in which the artery walls are thickened with a fatty material called a plaque. Atherosclerosis is a disease mainly of large and medium sized arteries
    1. Although most people are aware of this term in relation to the arteries or the heart, atherosclerosis is a systemic or body-wide disease affecting the aorta and arteries of the heart, brain, neck, abdomen, kidneys and legs (Figures 6 and 7) (See Carotid Endarterectomy and Arterial Surgery in the Leg)
    2. When a plaque narrows the artery enough, the organ being fed by the artery becomes starved of oxygen. (See Arterial Surgery in the Leg)
Figure 6 - Carotid angiogram demonstrating a 70% stenosis of the internal carotid artery. Figure 7 - Aortagram with lower extremity run-off showing a stenosis of the iliac artery. Courtesy S. Sadiq, MD
  • Aneurysms which are of three types
    1. 'Berry aneurysm' which is a small sac that forms on weakened arteries of the brain. It may rupture causing bleeding around and in the brain (Figure 8)
    2. Fusiform aneurysm which is a localized widening of a weakened artery such as in the aorta (abdominal aortic aneurysm), which is usually due to atherosclerosis
    3. Dissecting aneurysm which is due to a splitting of the intima (inner lining) of the artery wall. It is frequently due to trauma. This is followed by blood getting into the artery wall and lifting the intima thus narrowing the artery. Small clots may also form on the artery wall, break off and go to smaller vessels downstream (embolus), which may become blocked
  • Arteriovenous malformations (AVM) which are abnormal tangles of arteries and veins in which there is a direct connection between these vessels (capillaries are absent). AVMs are usually found in the brain and may rupture causing bleeding into the brain (Figure 9)
  • Fibromuscular dysplasia may cause irregular narrowing of arteries (Figure 10)
  • Tumors that have an abnormal blood supply and usually found in the brain or kidney
  • Bleeding into the stomach or bowel wall such as caused by an ulcer
Figure 8 - Large left internal carotid artery aneurysm. Courtesy R. Fessler, MDFigure 9 - An arteriovenous malformation. The arterial blood flows directly into veins.
Figure 10 - Fibromuscular dysplasia of a renal artery causing arterial narrowing. Courtesy S. Sadiq, MD

History and Examination

The history taken from the patient and the physical changes found by the physician depend on the pathology and organ involved

  • Atherosclerosis
    1. Stenosis (narrowing) or occlusion (blockage) of an artery to the brain may result in a stroke such as a temporary loss of vision, paralysis and/or loss of feeling on one side of the body, loss of speech, etc.
    2. Stenosis or occlusion of the lower aorta and arteries to the legs causes pain in leg muscles on exercise such as walking that goes away with rest (intermittent claudication), leg ulcers that do not heal and even gangrene
    3. Stenosis of a renal (kidney) artery may result in high blood pressure or evidence of kidney failure
    4. Stenosis or occlusion of any artery to the bowel may result in gangrene of the bowel with severe abdominal pain
  • Aneurysm
    1. Rupture of a berry aneurysm of a brain artery causes a subarachnoid hemorrhage (blood in the cerebrospinal fluid, CSF, that bathes the brain) or blood in the brain. The most common symptom is a severe headache. The patient may become unconscious. Other findings include the picture of a stroke
    2. A fusiform abdominal aortic aneurysm (AAA) may produce an abdominal mass that pulsates. Rupture of the AAA causes sudden severe abdominal pain followed by low blood pressure leading to shock due to massive blood loss from the aorta
    3. A dissecting aneurysm usually follows trauma to an artery. Stenosis or embolus may produce symptoms of repeated episodes of lack of oxygen to the organ involved, for example, if the artery feeds the brain a stroke may occur
  • Arteriovenous malformation
    1. Patients with an AVM in the brain may present with seizures or symptoms that may be mistaken for a stroke such as weakness on one side of the body
    2. With rupture of an AVM with blood in the fluid around the brain the patient may have a severe headache. Hemorrhage into the brain may produce the picture of a severe stroke
  • Tumor
    1. The symptoms that a patient presents depends on the organ involved with the tumor
    2. The most common organ for which angiography is used in the diagnosis of a tumor is the brain. These patients may present to the doctor with seizures, weakness, numbness, difficulty with speech and/or loss of some vision
  • Bleeding into the bowel is usually significant before angiography is considered. Bleeding is evident by blood in the stool

Tests

The tests that may be done prior to angiography are dependent on the involved organ and disease. Tests include:

  • Analysis of blood, urine and CSF
  • Doppler ultrasound of arteries looking for evidence of stenosis
  • Ultrasound of the abdomen for tumor
  • Computerized Axial Tomography scan (CAT scan) for tumor
  • Magnetic Resonance Imaging scan (MRI) for tumor
  • Magnetic Resonance Angiogram (MRA) arteries for stenosis, aneurysm and AVM
  • Magnetic Resonance Venogram (MRV) is a noninvasive method for outlining veins for various abnormalities of the veins

Indications and Contraindications

  • Angiography is indicated whenever the configuration of the arteries or veins needs to be determined in order to diagnose a disease or in the planning of surgery
  • Allergy to the iodine contrast material (solution containing a dye that shows on X-ray) that is injected for the angiogram is a relative contraindication. In many cases the patient can be medicated with an antihistamine and steroid to prevent the allergic reaction

Procedure

  • Diagnostic arteriography is carried out to make a diagnosis
    1. It is performed by puncturing the artery, usually a femoral artery in the groin with a needle. Other arteries may also be used
    2. A thin wire (guide wire) is passed into the artery and guided under fluoroscopy (X-ray control) towards the target artery
    3. A catheter is threaded over the guide wire into the target artery
    4. Contrast material is then injected through the catheter tip with the help of an automatic injector
    5. Serial X-ray films are taken of the arteries of interest. The catheter may be repositioned and more films are taken. When sufficient films are taken to make the diagnosis, the catheter is removed
    6. Pressure is applied over the artery for about 10-15 minutes. This allows blood to form a clot to seal the arterial puncture. However, this clot is not solid for about six hours. Therefore the patient is instructed to stay quiet in bed for that time. A special device may be used to place a stitch into the artery puncture site, however, not everybody is a candidate for this device
    7. A typical diagnostic arteriogram takes about one to one and half hours. Following the angiogram fluids are given to flush the contrast material from the body to reduce any possible toxicity to the kidneys
    8. Occasionally a special needle is placed directly in the artery of interest and the arteriogram performed by injecting the dye directly into the artery without the use of a catheter

Interventional Procedures

  • These procedures are extensions of the diagnostic arteriogram that attempt to treat the disorder. Not all patients need such treatment. The patient may be treated at the same time as diagnostic procedure but sometimes the patient may be rescheduled in order to consult with other doctors and plan a proper master plan. The interventional procedures are:
    1. Percutaneous balloon angioplasty (PTA) is used to treat a narrowed artery resulting from atherosclerosis. (Figure 11)
    • After the angiogram localizes the stenosis in the artery, a guide wire is placed through the stenosis
    • A special catheter with a balloon at the tip is placed with the balloon centered at the stenosis
    • The balloon is inflated under controlled pressure and causes the stenosis to be flattened against the artery wall
    • A blood thinner is given to prevent clotting at the angioplasty site
    • The balloon is deflated and the catheter is removed, and pressure held over the arterial puncture
    1. A stent is a special metal mesh that is used to keep a stenotic artery open (Figures 11, 12 and 13)
    • The stent is inserted collapsed over a balloon and positioned at the stenosis
    • Inflating the balloon expands the stent against the artery wall preventing re-stenosis
    • A blood thinner is given to prevent clotting at the stent
    • The balloon is deflated and the catheter removed following which pressure is held over the artery puncture
    Figure 11 - Left. Preoperative angiogram showing stenosis of the femoral artery. Middle. Balloon and stent in place. Right. Postoperative angiogram showing correction of the stenosis with a stent. Courtesy S. Sadiq, MD
    Figure 12a - Angiogram after stenting of iliac artery stenoses seen in figure 7. Courtesy S. Sadiq, MDFigure 12b - Stents in place. Courtesy S. Sadiq, MD
    Figure 13 - Angiogram following angioplasty of renal artery seen in figure 10. Courtesy S. Sadiq, MD
    1. Embolization is used to treat AVMs and vascular tumors (tumors that have many blood vessels and tend to bleed)
    • The purpose is to reduce the number of blood vessels usually as a prelude to surgery. The most common AVMs and vascular tumors for which embolization is used are in the head
    • After the diagnostic angiogram, a catheter is placed in the artery or arteries that feed the AVM or tumor. Various materials that promote clotting are injected into the feeding arteries in order to close these vessels and thus reduce bleeding during subsequent surgery
    • The catheter is removed following the procedure
    1. Wire coils may be used to treat certain aneurysms of the brain (Figure14)
    • After the diagnostic angiogram, a special fine catheter is positioned under fluoroscopy into the aneurysm.
    • Very fine platinum wire is passed through the tip of the catheter and coiled within the aneurysm, which promotes clotting within the aneurysm
    • The wire is separated from the catheter and the catheter removed
Figure 14a - Beginning of coil placement in aneurysm seen in figure 8. Courtesy R. Fessler, MDFigure 14b - Angiogram following completion of coil placement. Courtesy R. Fessler, MD

Complications

  • The most common complication is excessive bleeding at the puncture site in the artery with the formation of a large hematoma (clot) that has to be removed. A small clot is common and does not require special treatment
  • Clot formation in the artery that may result in stroke or loss of blood to a limb or organ such as a kidney
  • Rupture of a brain aneurysm
  • Fracture of a catheter resulting in the inability to remove the catheter segment ecept by direct surgery
  • Hemorrhage into the target organ
  • Bleeding into tissues from the blood thinners given
  • Seizures
  • Allergic reaction to the injected dye
  • Kidney failure

Postoperative care

  • The patient is monitored for blood pressure, pulse and respirations
  • The arterial puncture site is carefully observed for any excessive bleeding
  • At the end of about a six-hour bed rest the patient is walked and the puncture site observed (walk-test). If this test is passed the patient is discharged
  • Instructions for home care are given as well as an appointment for follow up care
  • If an intervention has taken place, after care will depend on the procedure, the condition of the patient and any special care required. The patient is usually kept in the hospital for at least 24-48 hours and may be kept on blood thinners during that time