Endovascular surgery

Endovascular surgery is a form of minimally invasive surgery that was designed to access many regions of the body via major blood vessels.Endovascular techniques were originally designed for diagnostic purposes. Basic techniques involve the introduction of a catheter percutaneously or through the skin, into a large blood vessel. Typically the blood vessel chosen is the femoral artery or vein found near the groin. Access to the femoral artery for example, is required for coronary, carotid, and cerebral angiographic procedures. The catheter is injected with a radio-opaque dye that can be seen on live xray or flouroscopy. As the dye courses through the blood vessels, characteristic images are seen by experienced viewers and can assist in the diagnosis of diseases such as atherosclerosis, vascular trauma, or aneurysms.

In recent years, however, the development of intravascular balloons, stents and coils have allowed for new therapies as alternatives to traditional surgeries such as CABG, Carotid Endarterectomy and Aneurysm clipping. Stents and coils are composed of fine wire materials such as platinum, that can be inserted through a thin catheter and expanded into a predetermined shape once they are guided into place.

Endovascular surgery is performed by radiologists, neurosurgeons, cardiologists, and vascular surgeons. The field is rapidly growing as its minimally invasive techniques offer an immediate advantage over more traditional, yet highly invasive surgeries. However, the science of endovascular surgery and its developing techniques are so new that it is currently difficult to compare the long term outcomes and complications of these patients. Several trials are underway, including CREST, and ISAT, among others.The most common and advanced form of endovascular surgery taking place today is an EVAR. This is a new technique developed to treat aortic aneurysms.

Recommendations for the Endovascular Treatment of Intracranial Aneurysms

Introduction

Intracranial aneurysms are common, with a prevalence of 0.5% to 6% in adults, according to angiography and autopsy studies. Most intracranial aneurysms are asymptomatic and are never detected. Some are discovered incidentally in neuroimaging studies and some produce symptoms due to compression of neighboring nerves or adjacent brain tissue. Others are detected only after they have ruptured and caused subarachnoid hemorrhage, a devastating type of stroke asso-ciated with 32% to 67% case fatality and 10% to 20% long-term dependence in survivors due to brain damage.

To prevent subarachnoid hemorrhage, physicians have developed methods to treat aneurysms. For ruptured aneurysms, early treatment within 24 to 72 hours has been recommended because the risk of subsequent rupture is high, with approximately 20% risk of rerupture in the first 2 weeks after subarachnoid hemorrhage. Each additional rupture substantially increases the risk of mortality and morbidity. Treatment has also been recommended for most unruptured aneurysms, although there is uncertainty about treatment of some small aneurysms <10 mm because their risk of rupture appears low. The American Heart Association formed this special writing group to summarize the literature and create recommendations on endovascular therapy of ruptured and unruptured intracranial aneurysms. This statement is meant to extend previous statements on treatment of subarachnoid hemorrhage and on treatment of unruptured aneurysms.During the review, it became evident that any recommendations would be based primarily on expert opinion weighing evidence only from nonrandomized cohort studies and case series.

Background

In 1937, Walter Dandy reported the first successful surgical clipping of the neck of an aneurysm. Microsurgical techniques have steadily evolved since then, with development of a variety of surgical approaches and metal aneurysm clips. Repair of aneurysms in nearly all intracranial locations is possible by placing a clip made from a stable metal (including platinum, titanium, tungsten, and steel alloys) across the neck of the aneurysm, thus excluding it from the cerebral circulation.

Endovascular treatment of intracranial aneurysms was first described in the early 1970s by Fedor Serbinenko, a Russian neurosurgeon. He used a vascular catheter with a detachable latex balloon to treat aneurysms, either by depositing the balloon directly into the aneurysm lumen or by occluding the artery from which the aneurysm arose.

In 1991, Guido Guglielmi was the first to describe the technique of occluding aneurysms from an endovascular approach with electrolytic detachable platinum coils, termed Guglielmi detachable coils (GDCs). GDCs are introduced directly into the aneurysm through a microcatheter and detached from a stainless-steel microguidewire by an electrical current . The aneurysm is packed with 1 or more GDCs, thereby excluding it from the circulation .

As clinical experience with this technique has increased and coil design has improved, coil embolization has been used with increasing frequency even in patients who could be treated by conventional surgical clipping. Furthermore, some centers are treating patients with surgical clipping only if they cannot be treated primarily by endovascular coil embolization therapy. In August 2002, it was estimated that 100 000 patients with intracranial aneurysms had been treated with GDCs at sites throughout the world, with approximately 1500 patients being treated per month.

Given the wide use of endovascular coil embolization to treat intracranial aneurysms, it is important to establish recommendations, based on the best available evidence, to define appropriate indications for coil embolization and other endovascular techniques in the context of surgical alternatives. The essential elements to compare are risk of morbidity and mortality, and efficacy, measurable in terms of reduced risk of aneurysm rupture after treatment.

Procedural Risk

Intracranial aneurysm treatment, by either surgery or endovascular coiling, may precipitate a complication that could lead to new symptoms, disability, or death. In comparing procedural risks, a measure of complications caused by the treatment itself would be ideal so that the impact of the therapy could be isolated from other aspects of presentation or medical care. For example, brain injury from subarachnoid hemorrhage at presentation or from aspiration of gastric contents during airway manipulation may lengthen hospitalization or result in disability, and these complications could obscure the impact of the procedure itself on outcomes. However, determinations of what “procedure-related” means are subjective and require judgment; hence, “measurements” of procedure-related complications are unreliable. In formulating these guidelines, we have favored comparisons of functional outcomes when available in the literature.

Functional outcomes after subarachnoid hemorrhage are highly dependent on the severity of the initial hemorrhage.Although researchers have attempted to adjust for differences in pretreatment prognosis, it is not possible to ensure that adjustment is adequate to compare results in different case series. Thus, comparison of results of case series of procedural risk in ruptured aneurysm treatment should be avoided.

As with all procedures, risk is affected by patient selection, technical expertise, and supportive services, and its measurement is influenced by the definition of the outcome and the judgment of the evaluator. Descriptions of retrospective case series, which dominate the literature on procedural risk of intracranial aneurysm treatment either by surgery or by endovascular coiling, should be considered skeptically given potential sources of bias and will be reviewed only briefly. Comparative studies that include patients treated by both modalities are more likely to assess outcomes impartially and may provide more reliable comparisons of surgery and endovascular coil embolization.