Angiography

Angiography is the procedure by which blood vessels of the body are visualised by injecting contrast or otherwise. Most popular contrast media are iodinated dyes which cast shadows of the vessels on x-ray imaging. When the imaging is done by continuous filming it is known as cine-angiography. Now a days most of the angiograms are cine angiograms. Cut film angiograms which used to be done earlier have become obsolete with the advent of good cine technology. Even films have almost disappeared, being replaced by CD or DVD.
Visualisation of the vessels in the retina is done by injecting a fluorescent dye known as fluorescein. Hence this form of angiography is known as fluorescein angiography. Dyeless angiography is possible with magnetic resonance imaging where the signals from the moving hydrogen particles in blood give the image. This is known as magnetic resonance angiography.
Conventional angiography using x-ray equipment is used for imaging the blood vessels of the heart and is known as coronary angiography. Imaging of peripheral vessels of the limbs is known as peripheral angiography. Imaging vessels of the kidney is known as renal angiography. Cerebral angiography is done to visualise the blood supply of the brain. Pulmonary angiography visualises the vessels of the lung. Intestinal blood supply is seen by mesenteric angiography.
Contrast injected for angiography can cause some problems rarely. There are various types of iodinated contrasts: non-ionic and ionic; hyperosmolar and iso-osmolar etc. Non-ionic contrast is costlier, by produces less of adverse effects like fall in blood pressure and nausea. Rarely the individual can be allergic to the contrast dye. In an individual with compromised or borderline kidney function, the dye can precipitate kidney failure, which may require dialysis.
Most of the X-ray angiograms are done using iodinated dye injected into blood vessels through small tubes known as catheters. Small skin punctures are made under local anaesthesia to introduce these tubes into the body. Site of puncture depends on the type of angiography to be performed. Coronary angiography can be performed by puncture of the radial artery at the wrist or the femoral artery in the groin. Cerebral and renal angiograms are usually done through the femoral route as the introduction of the catheter to these sites are easier by the femoral route. Same is true of angiography of the lower limb vessels and abdominal aorta. In case the lower limb vessels are not accessible due to occlusive disease, long catheters can be used from the upper limbs to access the lower limb vessels through the arch of aorta and descending aorta. Pulmonary angiography is done by accessing the femoral vein at the groin. It can also be achieved by a jugular puncture at the root of the neck, entering the veins which drain deoxygenated blood from the head and neck.

Glossary

Retina: Light sensitive layer of the eye which processes vision
CD: Compact disc used for digital recording
DVD: Digital versatile disk used for digital recording
Jugular: Large blood vessel draining deoxygenated blood from the head and neck
Aorta: Largest blood vessel carrying oxygenated blood to all parts of the body
Pulmonary: Related to the lungs
Femoral vein: Blood vessel draining deoxygenated blood from the lower limb (thigh and leg)
Coronary: Related to the blood vessels of the heart
Cerebral: Related to the brain
Renal: Related to the kidney
 

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