Nongalenic Arteriovenous Fistulas: History of Treatment and Technology

Kristen Upchurch, MD; Lei Feng, MD, PhD; Gary R. Duckwiler, MD; John G. Frazee, MD; Neil A. Martin, MD; Fernando Viñuela, MD

Disclosures

Neurosurg Focus. 2006;20(6) 

In This Article

History of Innovations Leading to Endovascular Treatment

Challenges of Endovascular Treatment

Due to the high flow in these lesions, treatment of nongalenic AVFs always carries the danger of rapid hemodynamic alteration, also known as normal perfusion pressure breakthrough, which may result in cerebral injury and death.[34,38,40] In addition, given their high flow and dilated venous drainage, the risk of inadvertently occluding the venous outflow of nongalenic AVFs has posed a particular challenge to treating these lesions with endovascular embolization.[25,38] Currently, however, this particular anatomical characteristic of nongalenic AVFs—the associated dilated varix—has made the fistulas especially amenable to modern endovascular techniques, given that this venous outlet can be used in the endovascular approach.

Despite the anatomical differences between nongalenic AVFs and other cerebrovascular lesions, technical advances originally made in the endovascular treatment of intracranial AVMs and aneurysms have been directly applicable to the embolization of nongalenic AVFs. These innovations have included the optimization of embolic agents, the development of new types of catheters, and the use of preembolization superselective angiography.

Embolic Agents: Historical Development From 1930 to the Modern Era

Embolization materials have gradually improved since 1930, when Brooks inserted a piece of muscle into a patient's carotid artery to embolize a carotid-cavernous fistula.[32] The first materials used were muscle, Gelfoam, and solid plastic particles; later advancements included detachable balloons, rapidly polymerizing liquid agents, and detachable coils. In 1960, Luessenhop and Spence[23] described the successful flow-directed embolization of a large left frontotemporal AVM by using solid particles (four spherical methyl methacrylate emboli) introduced into the surgically exposed left carotid artery. In 1974, Serbinenko reported his innovative use of detachable balloons to occlude cerebral vessels by percutaneously introducing balloon catheters into the vascular system and maneuvering them into the intracranial arteries. In the early 1980s, rapidly polymerizing cyanoacrylates were established as efficacious in both the intraoperative and transfemoral embolization of cerebral AVMs.[7,10,41] In the 1990s, Guglielmi and coworkers[12,13,14] de scribed their successful use of electrolytically detachable platinum coils and soft microcatheters to perform endovascular electrothrombosis of intracranial aneurysms (Fig. 10). On the basis of these innovations, vascular neurosurgeons and interventional neuroradiologists began to work together to combine open surgery with intraoperative and/or transfemoral embolization of nongalenic AVFs as well as AVMs.[22,33,38,43]

Figure 10.

Illustration of the most recent Guglielmi detachable coil (GDC 360), manufactured in 2004.

Successes and Failures in Embolization of Nongalenic AVFs

This technological progress improved the efficacy of en do vascular embolization as treatment for cerebrovascular lesions in general and made possible its application to nongalenic AVFs. However, as in the history of any new technology, attempts to treat nongalenic AVFs with interventional neuroradiology were initially often unsuccessful. The specific causes of failure in individual cases were diverse: inability to control the fistula's high flow;[4,38] imprecise balloon placement too proximal to the fistula site;[15] development of new collateral feeding arteries after embolization;[15] imprecise placement of platinum coils; and failure to occlude all feeding arteries, probably due to incomplete angiographic visualization of the lesion angioarchitecture.[3] For some patients with nongalenic AVFs, combined endovascular and surgical approaches were planned in advance. Others whose endovascular embolization failed were subsequently advised to undergo craniotomy only after interventional neuroradiological techniques failed.[3,35,36,38]

Superselective Angiography

The root causes of past unsuccessful embolization of nongalenic AVFs have lain primarily in technological limitations, including the inability to visualize AVF angioarchitecture fully due to incomplete angiographic injections. In the past few decades, the development of pre treatment selective and superselective angiography has made possible the accurate delineation of lesion angioarchitecture is essential to planning successful lesion-specific treatment, whether endovascular, surgical, or both.[16,20,38,39]

Selective and superselective catheterization of cortical vessels was made feasible by the development of transvascular navigation techniques in the 1970s and 1980s. Of particular importance was the innovation of balloon catheters that can be maneuvered along the acute curves of cortical vessels without causing vascular injury.[9,18,19,28,29,32,39] Due to these technical advances, present-day superselective angiography can produce detailed images of a cerebrovascular lesion's anatomy. This precise angioarchitectural map then can be used to determine the best endovascular approach, whether transarterial or transvenous, as Houdart[16] demonstrated in his angioarchitecture-based classification of intracranial vascular lesions (Fig. 11). Importantly, super selective angiography provides both anatomical and functional information. It delineates the feeding arteries and the venous drainage of the nongalenic AVF and also permits estimation of the arteriovenous transit time of an arteriovenous shunt.[39] This estimated transit time is important in calculating the correct rate of cyanoacrylate injection to occlude the fistula safely.[38,39,41]

Figure 11.

Illustration of the most recent Guglielmi detachable coil (GDC 360), manufactured in 2004.

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