When an aneurysm occurs, which is essentially a bulge in a blood vessel, the size of the cross section of an artery more than doubles. This considerably increases artery wall tension and therefore the risk of rupture. An aneurysm in the brain leads to life-threatening hemorrhaging, requiring immediate emergency surgery. "10 % of patients with a burst aneurysm die on the way to hospital", says Enseñat. “Aneurysms are an extremely complex disease with a high mortality rate, 46 % during the first 30 days after treatment. Three quarters of the patients who survive will never fully regain their ability to work." To avoid blood vessel enlargement and rupture, cerebral aneurysms are treated by a procedure where the bulge in the blood vessel is separated from the blood flow with a clip.
Fast, reliable checking of blood flow
A successful outcome of such neurovascular surgery depends on cutting off blood flow to the aneurysm while maintaining blood flow in the neighboring functional blood vessels. However, a purely visual evaluation of the surgical site is inadequate, as it is extremely difficult to inspect vascular circulation. “Postoperative evaluation shows that between 4 and 8 % of deformities are not completely clipped and 8 to 12 % of neighboring functional blood vessels are closed by mistake,” says Enseñat. For the first time, fluorescence-aided videoangiography with the Leica FL800 fluorescence module enables neurosurgeons to watch blood flow in the brain during surgery via the surgical microscope, without additional measuring apparatus.
The patient is injected intravenously with ICG (IndoCyanineGreen) dye, which is well tolerated and spreads through the bloodstream quickly. Excited by light in the 800 nanometer wavelength range, the ICG fluoresces and emits light at a wavelength of 835 nanometers. This infrared light, which is invisible to the human eye, is filtered out by means of the microscope optics and then transformed into a black-and-white image by a near infrared