Temporary vessel occlusion is a test performed to better understand the blood flow to the brain and the individual ability of a patient to adapt to a loss of certain arteries. Permanent vessel occlusion involves blocking flow through a particular artery. This can be done surgically from the outside where the vessel is tied or endovascularly where small coils are placed inside the artery. Temporary vessel occlusion is always performed prior to any possible permanent vessel occlusion. Typical instances where permanent vessel occlusion can be considered are; if an artery has been seriously damaged beyond conventional repair and has a risk of creating clots that will then flow to the brain and if a surgical procedure will require working closely to a critical artery.
Prior to undergoing temporary vessel occlusion it is necessary to perform a cerebral angiogram. A cerebral angiogram provides a roadmap of the blood vessels of the brain. Physicians use this blood vessel roadmap to determine how a particular patient’s brain is supplied with blood and whether the artery being tested is of critical value, i.e. without the artery the patient will have significant disability. In the event that an artery in question is of critical value then the procedure will stop at this point. Assuming an artery is not critical; a small balloon can be placed in the artery of question and inflated to temporarily stop blood supply from the artery to the brain. During balloon inflation patients are closely monitored and asked to perform certain tasks. This portion on the procedure usually takes 20-25 minutes.
If a patient passes this part of the examination then their blood pressure, under close monitoring, is artificially lowered. Blood pressure is lowered to simulate a low flow condition and improves the accuracy of testing. Again the patient is closely monitored and asked to perform certain tasks and this portion takes another 20-25 minutes. At the end of testing all catheters are removed and direct pressure is held over the groin puncture until bleeding has stopped. Patients are then taken to a recovery area where they will be closely monitored for 4-6 hours.
Permanent vessel occlusion is usually only considered after temporary occlusion testing has shown that a patient will tolerate the procedure. However, there are emergent conditions where it is necessary to permanently occlude a blood vessel because to wait for a temporary occlusion test would endanger a patient’s life, e.g. a patient actively hemorrhaging. A permanent vessel occlusion involves placing small platinum micro-coils within the artery to be shut down.