The microvascular Doppler--an intraoperative tool for the treatment of large and giant aneurysms.

One of the problems especially associated with large and giant aneurysms is the control of the patency of the parent artery and the exclusion of the aneurysm. While the exclusion can be tested by puncture (which may sometimes be problematic), the patency can only be controlled by intraoperative angiography or recently, by microvascular intraoperative Doppler. The device we use has a high resolution and is equipped with probes as small as 0.3 mm with which all visible vessels with diameters of more than 0.1 mm can be investigated. Local stenoses above a diameter reduction of 40% can be easily detected by localized accelerations and changes in the pulse curves. Our recent experience with 11 giant and 13 large aneurysms has revealed marked discrepancies between an apparently well placed clip and an obviously open vessel on the one hand, and the haemodynamic reality revealed by the Doppler on the other. We were able to decide whether the flow was undisturbed, or whether there was an haemodynamically non-effective lumen reduction due to a tight clip, or if there was severe stenosis or a total occlusion. In five cases with severely disturbed flow after clipping, we had to change our strategy: we resected the aneurysms and sutured the neck, performed an end-to-end anastomosis, coated the aneurysm, or repositioned the clips. In cases in which we did not have full view of the neck, the Doppler guided us to a proper clip position. We conclude that especially for large and giant aneurysms, the microvascular interoperative Doppler is a valuable tool.