Bypass (surgical)

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In medicine, a bypass generally means an alternate or additional route for blood flow, which is created in bypass surgery, e.g. coronary artery bypass surgery by moving blood vessels or implanting synthetic tubing. Vessels frequently used for the bypass are large veins taken from the patient's leg. When and where possible, however, an artery 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.

[edit] ELANA

Excimer laser assisted nonocclusive anastomosis (ELANA) is a technique in vascular surgery and neurosurgery 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 (anastomosis) to create a bypass in or to the brain. The only real differences involve how the recipient artery is opened. In conventional techniques the recipient artery is temporarily interrupted (occluded with clips) and opened using microscissors or scalpel while in the ELANA technique blood flow is not interrupted and the opening (arteriotomy) 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 ischemia to the regions supplied by the artery receiving the bypass. The technique is most valuable in neurosurgery, as brain cells are particularly sensitive to the lack of blood supply (ischemia) 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 stroke 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 Utrecht, the Netherlands, 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 Times[1] in December 2006.

[edit] References

• Tulleken CA, Verdaasdonk RM, Mansvelt Beck HJ, et al. "The modified excimer laser-assisted high-flow bypass operation". Surg. Neurol. 46:424––429, 1996
• Hendrikse J, van der Zwan A, Ramos LM, et al. "Hemodynamic compensation via an excimer laser-assisted, high-flow bypass before and after therapeutic occlusion of the internal carotid artery". Neurosurgery 53:858–863, 2003
• Streefkerk HJ, van der Zwan A, Verdaasdonk RM, et al. "Cerebral Revascularization". Advances and Technical Standards in Neurosurgery 28:145–225, 2003
• Denise Grady: "With Lasers and Daring, Doctors Race to Save a Young Man's Brain." The New York Times December 19, 2006