The concept of a Hybrid Angio-Surgical Suite (HASS) emerged as a solution to the complexity of cerebrovascular surgery and the need for immediate intraoperative feedback. It combines the capacity of both operating room and interventional suite --- a standard operating room equipped with a biplane or single plane angiogram machine. Early studies with intraoperative portable digital subtraction angiography (DSA) — early “hybrid surgery” for different cerebrovascular diseases -- showed that the intraoperative angiogram (IOA) altered surgical management, frequently by avoiding additional surgery [1–5]. With the recent enormous advancement of angiographic equipment, and hybrid operating tables, endovascular products and techniques, the combined multi-modality treatment with hybrid techniques has significantly improved patient outcomes and made many previously untreatable conditions treatable [5–8]. The hybrid angio/surgery suite is becoming a standard facility for many hospitals around the world. Many neurosurgeons and neurointerventionists use it for treatment of cerebrovascular diseases, but when to use it, what cases are suitable for its use, who can use it and how to use it remain debatable. In this paper, we examine the literature on case reports and series using the hybrid angio-surgical suite. We discuss the indications for using HASS on different types of cerebral vascular disease including cerebral aneurysm, arteriovenous malformation (AVM), dural arteriovenous fistula (DAVF), carotid stenosis/occlusion and other non-cerebral vascular diseases.

The routine or selective use of the IOA in aneurysm surgery has long been advocated because of its low risk-to-benefit ratio [1–4, 9–12]. The 3D rotational angiography and flat-panel detector computed tomography have further advanced this intraoperative armamentarium since the 1960s by its rapid image acquisition and ability to overcome the artifacts from aneurysm clips and coils [9–12]. Chiang et al. [2] reported repositioning of the clip in 11% of the aneurysms clipped because of residual aneurysms (6.5%), parent vessel occlusion (3%) or both (1.5%), after discovery with routine use of IOA. Tang et al. [3] reported positive IOA findings in 12.4% of aneurysms clipped, which prompted changes in their surgical strategies.

Currently, HASS was commonly used for hybrid treatment of giant brain aneurysms, especially giant paraclinoid and basilar tip aneurysms. These aneurysms tend to rupture intraoperatively, as safe dissection is often limited by the mass effect of the aneurysms. In these cases, flow arrest and decompression of aneurysms are achieved in several ways, such as occlusion of common carotid artery (CCA) and external carotid artery (ECA) for retrograde suction [13], proximal balloon occlusion [14, 15]. In these early reports, the authors placed the balloon into the proximal parent artery, whereas in those of Thorell et al. [16] and Steiger et al. [17], the occlusion was performed intracranially below the aneurysmal orifice or neck. Hu et al. [18] first reported a combination of endovascular and surgical approaches to treat giant ophthalmic artery aneurysms in a hybrid operating theater. They used a dye in the contrast to visualize the balloon, allowing for improved accuracy in placement of the balloon at the orifice of the aneurysm. This technique virtually removes the risk of intraoperative rupture because there is no blood flow into the aneurysm after the balloon is fully inflated.

Another advantage of HASS in the treatment of aneurysms is the immediate resue of complications from intitial procedures (either of endovascular embolization or surgical clipping). Qiu et al. [15] reported immediate rescue craniotomy for clipping following intraoperative rupture of middle cerebral artery (MCA) aneurysm embolization; Elhammady et al. [6] reported a salvage procedure in which an adjuvant endovascular balloon was used for proximal and distal control for an unexpected and uncontrolled rupture during clipping of a 2 cm paraclinoid aneurysm. Although this wasn’t done in a HASS, immediate availability of endovascular support can be used in similar situatiosn with improved outcomes.

Currently there is no consensus on AVM treatment, especially for the Spetzler-Martin (SM) grade III to V patients. Embolization prior to surgery is typically done in patients with high SM grade lesions in an effort to decrease the size of the malformation and to eliminate high-risk characteristics, including aneurysms and fistulas [19]. A decrease in complications and improvement in outcomes can be expected by eliminating difficult surgical areas and reducing the intraoperative bleeding and operation times with pre-op embolization. Normally pre-op embolization for an un-ruptured AVM is done prior to surgery in separate single or multiple sessions. Thus, HASS is not generally used for the pre-op embolization. But when intro-procedural rupture happens, HASS will make a difference for the patient’s outcome. Dyna CT of the angiogram machine is available to detect a hematoma. CT guided, external ventricular drainage placement can be performed instantly, and subsequent craniotomy can be done immediately.

The most useful function of HASS for AVM surgery is to confirm complete resection of an AVM nidus to avoid repeat surgery. Many studies have shown the necessity of IOA to avoid repeated surgery for residual AVM [1, 19–21]. In Kotowski’s series [22], in 16% of cases (22% for unruptured AVM and 13% for ruptured AVM), intraoperative imaging visualized AVM remnants ≤3 mm and allowed for completion of the resections in the same sessions which was missed on Indocyanine Green (ICG) angiography. The authors concluded that ICG angiography is recommended as a complement rather than as a replacement of DSA. It is believed that difficulties in visualization of remnants in ICG angiography are generally due to the small size, not to a deeper location. Modern HASS with flat panel detector coupled to a frameless neuronavigation system can guide the localization of the vascular lesion, such as residual AVM with intraoperatively acquired Dyna CT/XperCT and 3D rotational angiography datasets. Neuronavigation can be updated at any time by co-registration with intraoperative 3D rotational angiography or Dyna CT/XperCT datasets.

One specific major advantage of HASS is in the management of vascular emergency interventions. For patients suffering from a ruptured AVM with intracerebral hemorrhage and mass effect with herniation, the hybrid OR will make a big difference in outcome. In these cases, hematoma evacuation needs to be done urgently, but a high quality angiogram is also needed for assessing the AVM nidus for further surgical intervention after successful hematoma evacuation. The dedicated HASS setup has made it possible for the surgeon to assess the hematoma by Dyna CT and AVM angiostructure by intraoperative 3D angiogram, continue emergent treatment by microsurgical removal of the intracerebral hematomaand and the AVM, and for final confirmation of complete resection – all without the necessity of additional transport of the patient.

For carotid artery disease, the endarterectomy (CEA) is normally the first treatment option, with carotid stenting being an alternative option for cases with contraindications for CEA. In routine CEA, IOA isn’t regularly used; however, in some difficult cases, the HASS may be the only option, such as cases with long segment stenosis extending distally to the skull base and proximally to the origin site of CCA.

László Pintér [37] first reported a hybrid procedure for a long, total occlusion of the CCA that combines the use of internal carotid artery (ICA) CEA and the use of retrograde ring-stripping of the CCA and angioplasty/stenting of residual stenosis at the origin of the vessel. The hybrid procedure offers the surgeon control against distal emboli and angiographic guidance during the retrograde thromboendarterectomy. Shin et al. [38] used direct exposure of the common carotid artery for carotid angioplasty/stenting due to tortuous vasculature access via the femoral route. Simultaneous CEA and CAS for high-grade bilateral carotid stenosis has been reported by Xu et al. [39]

Symptomatic chronic total occlusion of the carotid artery presents another challenging situation. A few cases of endovascular angioplasty for total occlusion of ICA have been reported [40, 41], but it is a challenging procedure. Jiao’s group described a large series of recanalization of chronic carotid artery occlusions with carotid endarterectomy or hybrid procedure [42], which include Fogarty catheter embolectomy and carotid angioplasty/stenting. The hybrid procedure makes recanalization of long segment occlusions possible.

As indicated in the Shih’s report [43], hybrid surgery has a lot of advantages in comparison to the femoral endovascular approach. The hybrid technique allows insertion of the endovascular sheath into the true lumen with direct visualization, possibly saving operating time that would otherwise be spent on attempting blind recanalization in the occluded ICA segment. Another advantage is the avoidance of distal embolic stroke due to occlusion of the common carotid artery.