In
medicineMedicine is the art and science of healing. It encompasses a range of health care practices evolved to maintain and restore health by the prevention and treatment of illness....
, a
bypass generally means an alternate or additional route for
blood flowBlood flow is the flow of blood in the cardiovascular system.It can be calculated by dividing the vascular resistance into the pressure gradient.-Physics:...
, which is created in bypass surgery, e.g.
coronary artery bypass surgeryCoronary artery bypass surgery, also coronary artery bypass graft surgery, and colloquially heart bypass or bypass surgery is a surgical procedure performed to relieve angina and reduce the risk of death from coronary artery disease...
by moving blood vessels or implanting synthetic tubing. Vessels frequently used for the bypass are large
veinIn the circulatory system, veins are blood vessels that carry blood toward the heart. Most veins carry deoxygenated blood from the tissues back to the heart; exceptions are the pulmonary and umbilical veins, both of which carry oxygenated blood...
s taken from the patient's leg. When and where possible, however, an
arteryArteries are blood vessels that carry blood away from the heart. All arteries, with the exception of the pulmonary and umbilical arteries, carry oxygenated blood.The circulatory system is extremely important for sustaining life...
is cut from one place and reconnected to another artery, which supplies a region that needs the blood supply more than the original site.
In
medicineMedicine is the art and science of healing. It encompasses a range of health care practices evolved to maintain and restore health by the prevention and treatment of illness....
, a
bypass generally means an alternate or additional route for
blood flowBlood flow is the flow of blood in the cardiovascular system.It can be calculated by dividing the vascular resistance into the pressure gradient.-Physics:...
, which is created in bypass surgery, e.g.
coronary artery bypass surgeryCoronary artery bypass surgery, also coronary artery bypass graft surgery, and colloquially heart bypass or bypass surgery is a surgical procedure performed to relieve angina and reduce the risk of death from coronary artery disease...
by moving blood vessels or implanting synthetic tubing. Vessels frequently used for the bypass are large
veinIn the circulatory system, veins are blood vessels that carry blood toward the heart. Most veins carry deoxygenated blood from the tissues back to the heart; exceptions are the pulmonary and umbilical veins, both of which carry oxygenated blood...
s taken from the patient's leg. When and where possible, however, an
arteryArteries are blood vessels that carry blood away from the heart. All arteries, with the exception of the pulmonary and umbilical arteries, carry oxygenated blood.The circulatory system is extremely important for sustaining life...
is cut from one place and reconnected to another artery, which supplies a region that needs the blood supply more than the original site. Generally the blood flow in the receiving vessel is temporarily interrupted or reduced while the bypass is connected. To create a bypass to a critical artery, the connection can be made while blood is flowing through the receiving vessel with the ELANA operating technique.
ELANA
Excimer laser assisted nonocclusive anastomosis (ELANA) is a technique in
vascular surgeryVascular surgery is a specialty of surgery in which diseases of the vascular system, or arteries and veins, are managed by medical therapy, minimally-invasive catheter procedures, and surgical reconstruction. The specialty evolved from general and cardiac surgery...
and
neurosurgeryNeurosurgery is the surgery discipline focused on treating the central nervous system, peripheral nervous systems and spinal column diseases amenable to surgical intervention....
to create a bypass without interrupting blood supply in the recipient blood vessels. This is a significant advance because the interruption of blood supply to those blood vessels (i.e., in the brain or heart) could cause a stroke or a rupture of the aneurysm.
The ELANA technique is a subtle modification of existing methods to establish a connection between blood vessels (
anastomosisAn anastomosis is a network of streams that both branch out and reconnect, such as blood vessels or leaf veins. The term is used in medicine, biology, mycology and geology.-Medicine:...
) to create a bypass in or to the brain. The only real differences involve how the recipient
arteryArteries are blood vessels that carry blood away from the heart. All arteries, with the exception of the pulmonary and umbilical arteries, carry oxygenated blood.The circulatory system is extremely important for sustaining life...
is opened. In conventional techniques the recipient artery is temporarily interrupted (occluded with clips) and opened using microscissors or
scalpelA scalpel is a small but extremely sharp bladed instrument used for surgery, anatomical dissection, and various arts and crafts. Scalpels may be disposable or re-usable. Re-usable scalpels can have attached, resharpenable blades or, more commonly, non-attached, replaceable blades...
while in the ELANA technique blood flow is not interrupted and the opening (
arteriotomyArteriotomy is a medical term for an opening or cut of an artery wall. Also called arterotomy. Used mainly in :vascular surgery.Either a transverse or a longitudinal incision can be made....
) is created with radiation from a 308nm Excimer Laser delivered through a catheter inserted in the vessel that will become the bypass while blood continues to flow through the artery that receives the bypass. This subtle difference, however, is very important for the safety of the procedure and eliminates the risk of
ischemiaIn medicine, ischemia is a restriction in blood supply, generally due to factors in the blood vessels, with resultant damage or dysfunction of tissue...
to the regions supplied by the artery receiving the bypass. The technique is most valuable in neurosurgery, as
brain cellA neuron is an excitable cell in the nervous system that processes and transmits information by electrochemical signaling. Neurons are the core components of the brain, the vertebrate spinal cord, the invertebrate ventral nerve cord, and the peripheral nerves...
s are particularly sensitive to the lack of blood supply (
ischemiaIn medicine, ischemia is a restriction in blood supply, generally due to factors in the blood vessels, with resultant damage or dysfunction of tissue...
) that would be caused by traditional methods of bypass creation. The bypasses created with the help of the ELANA can be to one of the major arteries in the brain (extracranial to intracranial EC-IC bypass) or between two arteries in the brain (intracranial to intracranial).
Surgeons are creating such a bypass mainly as a step in the treatment of patients with unclippable and uncoilable giant aneurysms or tumors at the skull base or to treat patients at risk of
strokeA stroke is the rapidly developing loss of brain function due to disturbance in the blood supply to the brain. This can be due to ischemia caused by thrombosis or embolism or due to a hemorrhage...
who can not be treated otherwise.
The ELANA technique has been extensively described in medical literature. It was developed in 1993 by Cornelis A.F. Tulleken, professor of neurosurgery at the University Medical Center
UtrechtUtrecht city and municipality is the capital and most populous city of the Dutch province of Utrecht. It is located in the eastern end of the Randstad, and is the fourth largest city of the Netherlands, with a population of 300,030 in 2007...
, the
NetherlandsThe Netherlands is a country in Northwestern Europe, constituting the major portion of the Kingdom of the Netherlands. It is a parliamentary democratic constitutional monarchy. The Netherlands borders the North Sea to the north and west, Belgium to the south, and Germany to the east...
, to find a way to treat patients with a bypass to a major cerebral artery without the risk of cerebral ischemia during the procedure. The surgery of some patients has been reported upon in the media e.g., in
The New York TimesThe New York Times is an American daily newspaper founded in 1851 and published in New York City. The largest metropolitan newspaper in the United States, "The Gray Lady"—named for its staid appearance and style—is regarded as a national newspaper of record...
http://www.nytimes.com/2006/12/19/health/19brai.html in December 2006.