Intraoperative angiography should be standard in cerebral aneurysm surgery
© Friedman and Kumar; licensee BioMed Central Ltd. 2009
Received: 10 March 2009
Accepted: 30 April 2009
Published: 30 April 2009
Intraoperative angiography (IOA) has proven to be a safe and effective adjunct to surgical repair of cerebral aneurysms. Substantial practice variation exists regarding use of this modality in different centers, including use of IOA routinely, selectively, or rarely. In this editorial, we discuss our experience and review the existing literature to develop an argument for routine use of IOA during cerebral aneurysm surgery.
Intraoperative angiography (IOA) has been considered since the 1960s for use during surgical repair of cerebral aneurysms. The potential to confirm complete aneurysm occlusion and patency of the parent vasculature intraoperatively are the key clinical uses that underlie IOA. However, no consensus exists regarding routine use of IOA in cerebral aneurysm surgery. Different institutional paradigms include use of IOA rarely or never, selectively based on aneurysm complexity, or routinely in all aneurysm cases.
Intraoperative angiography is both effective and accurate. In a single-center study of 517 aneurysms that underwent IOA during cerebral aneurysm surgery, a 12.4% revision of clip placement due to abnormalities found on IOA was reported. The largest percentage of parent vessel occlusions were related to aneurysms of the proximal internal carotid artery. Aneurysms greater than 15 mm were independent predictors for the need for clip revision. The same study looked at the accuracy of IOA: the accuracy rate of IOA in detecting abnormalities as compared to postoperative angiography was 95%.
While surgical repair of large and/or complex aneurysms carries a higher likelihood of findings on IOA leading to clip revision, even experienced surgeons cannot adequately predict the need for IOA on a selective basis. In a study of 200 patients treated at an experienced center, all of whom underwent IOA, 20% were predicted by the surgeon to need IOA, while 80% were predicted to not need IOA. The prediction was based on location, size, and unique features. Of the 159 cases not predicted to need IOA, 7 (4.4%) needed clip revision due to aneurysm remnants, parent vessel occlusions, and undiagnosed aneurysms. Even in the most experienced hands, the potential for abnormal findings on IOA cannot be predicted with enough accuracy to justify selective use.
The potential value of IOA must be weighed against the morbidity and practical challenges of the procedure. Complications of IOA include stroke, dissection, emboli, arterial dissection, and hematoma. Complication rates have been reported in the range of 0.4% to 2.6%, and in our experience the risk of IOA was 3%. [2–5] While this represents increased morbidity compared to conventional cerebral angiography, these complication rates compare favorably to the rate of complications of surgical aneurysm repair which may be amenable to correction with IOA.
The biggest practical challenge of performing IOA routinely is having a skilled practitioner available to perform the procedure. This is particularly the case for night and weekend surgery. In our experience with implementing IOA routinely at two institutions, lack of radiology support led to inability to perform IOA in 35% of cases.  For this reason, implementation of a program of routine IOA requires a small number of "champions" that are committed to performing the procedure irrespective of schedule. The speed with which the IOA can be obtained is also a critical practical consideration, since in the event of parent vessel occlusion rapid restoration of flow is required to prevent stroke. We generally place a sheath in the femoral artery in the angiography suite before the operation, to facilitate rapid vascular catheterization and angiography intraoperatively. The responsiveness and coordination of the radiology team is also critical in the timeliness of results. This coordination is facilitated by performing IOA routinely, to build the experience and refine the systems. Other causes for not obtaining IOA in our experience included lack of radiolucent head holders, positioning of the patient in the lateral position, trapping or wrapping of the aneurysm, and individual patient contraindications to angiography. 
It is our opinion that IOA should be performed routinely on all patients undergoing cerebral aneurysm surgery. Morbidity due to incomplete aneurysm occlusion and/or parent vessel occlusion is not infrequent and is clinically important, and both complications may be avoided in certain cases by IOA. The limited morbidity of IOA is greatly outweighed by these potential benefits. Performing IOA in selective cases will not maximize the potential value since the need for IOA cannot be completely predicted. Even the simplest aneurysm repair in the most experienced hands can have complications potentially amenable to discovery by IOA with consequent correctional intervention. Finally, optimization of reliability, speed, and efficacy of IOA can only be achieved within an institution when its use is routine.
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- The pre-publication history for this paper can be accessed here:http://www.biomedcentral.com/1471-2482/9/7/prepub