Romanian Neurosurgery | Volume XXX | Number 4 | 2016 | October - December Article When flow diverters fail: short review and a case illustration of a device failure Marco Zenteno 1, Angel Lee 1, Jennifer Lorena Herrera Bejarano 2, Guru Dutta Satyarthee 3, Hernando Raphael Alvis-Miranda 2,Luis Rafael Moscote-Salazar 2 1MEXICO, 2COLOMBIA, 3INDIA DOI: 10.1515/romneu-2016-0075 Romanian Neurosurgery (2016) XXX 4: 467 – 474 | 467 DOI: 10.1515/romneu-2016-0075 When flow diverters fail: short review and a case illustration of a device failure Marco Zenteno 1, Angel Lee 2, Jennifer Lorena Herrera Bejarano 3, Guru Dutta Satyarthee 4, Hernando Raphael Alvis-Miranda 5, Luis Rafael Moscote-Salazar 6 1“Manuel Velasco Suarez” National Institute of Neurology and Neurosurgery, Ciudad de Mexico, MEXICO 2Hospital Angeles Inn Universidad, Ciudad de Mexico, MEXICO 3Physician, Universidad del Rosario, COLOMBIA 4Associate Professor of Neurosurgery, All India Institute of Medical Sciences, New Delhi, INDIA 5Resident of Neurosurgery, Universidad de Cartagena, Cartagena de Indias, COLOMBIA 6Red Latino, Latin American Trauma & Intensive Neuro-Care Organization, Bogota, COLOMBIA Abstract : The ultimate aims of treatment of the intracranial aneurysms are reconstruction the vessel wall and correcting the hemodynamic disturbance. A flow diverter (FD) is a stent placed inside lumen of the parent artery with aim to blood flow reduction into the aneurysms sac to the extent of almost stagnation leading to gradual onset of progressive thrombosis and neointimal lining of arterial wall remodeling to maintain blood outflow into perforators the side and branches. Flow diverter is considered as an effective treatment for fusiform, wide-necked, large and giant intracranial unruptured aneurysms. However, FD implantation may also be associated with growth and rupture of residual aneurysms. The most frequent complication of endovascular aneurysms management is thromboembolic events and less common are intra and postoperative hemorrhagic aneurysmal rupture. Authors report a case where a lack of operation of the device as illustration is presented to demonstrate the shortcomings of this new type of devices. Key words : Flow diverter device, aneurysms, neuro-intervention Introduction blood flow into the aneurysm and to restore The treatment of intracranial aneurysms the physiological flow. The aneurysm (IA) is based on principle of isolating treatment can be accomplished by surgical aneurysm from parent vessels, occluding clipping of aneurysm at neck allowing definitive and complete aneurysm isolation 468 | Zenteno et al - Flow diverter device failure but carries a high risk of complications such as maintaining normal blood flow [1] into the cerebral edema, arterial vasospasm, and branches of the main artery. infarction. A large variety of new devices for The ability of a stent to accomplish these the treatment of IA are popping up in recent goals is dependent on the amount of metal on years with the aim to improve the prognosis of its surface, the rigidity of FD, and bioactivity patients , however, the understanding of local of the stent material [15]. hemodynamics is not still incomplete. Flow Additionally, the placement of the Flow diverter devices (FD) are device, which is diverters could change vessel anatomy, similar to the stent, designed with aim to aneurysm and finally flow to brain regions [1, achieve normal vessel reconstruction, and 10]. causing blood flow diversion along the Hemodynamic studies suggest stent with a anatomical course and sparing out of the flow porosity above 50-70 % , can cause significant vector of the neck and dome of the aneurysm. reduction of the flow rate to the aneurysm sac Recent publication show successful use of flow [1, 9, 10, 12, 13, 14], leading to progressive in the management of intracranial aneurysm, formation of thrombus and this finally causing but these may fail also. [1–4] Hemodynamic total occlusion [3, 4, 10, 13, 14, 16]. However, factors are considered to play the biggest factor clinical results of Flow diverters can be varied in the progression and rupture of IA. Recently [4] and also dependent on morphology of several cases of FD failure are reported. [1, 2] aneurysm, size of neck and presence of authors reports an additional case of FD device branching vessel originating from fundus. In and hence these devices should be considered addition to the Flow diverters, other treatment for experimental use. options of IA include coil embolization and According to the proposed goal in the surgical clipping [3]. The middle cerebral treatment of intracranial aneurysms, FD is artery aneurysms were evaluated in the study designed in a way to ensure complete of International cohort subarachnoid management of IA and preventing possible aneurysms (ISAT) observed required two associated post-treatment complication [5] i.e. complementary procedures including surgical bleeding, reconstruction of the vessel wall and approaches and endovascular for the complete correction of the hemodynamic flow occlusion of the aneurysm [6, 15]. The surgical abnormality [1]. Flow Diverters represents a aneurysm clipping of has been considered for new generation of stents as a superior new the treatment of middle cerebral artery alternative treatment for IA. [4, 10, 11, 12- 16]. aneurysms after endovascular therapy as Flow diverters are a stent, placed inside the presence of branches growing from where the lumen of the main artery to reduce blood flow aneurysm arises or the same within are always to the aneurysm causing stasis and gradually considered as risk factors [6]. progressive thrombosis and subsequent Bracard et al. analyzed 140 patients with remodeling of the inner layers of the blood middle cerebral artery aneurysms, 73 had vessel wall [4, 11, 13, 15]; keeping and unruptured aneurysms. All cases received as Romanian Neurosurgery (2016) XXX 4: 467 – 474 | 469 embolization coil treatment without any other diameter [6]. These are important adjuvant technique [12]. Thromboembolic considerations which play a role in making a complications were noted in 8.5%, a high proper decision during treatment and incidence of these complications was evident influencing its possible outcomes [4]. in ruptured cases 13.7% versus 3.8% Bleeding complications of Flow Diverters: unruptured aneurysms [6, 9]. However, most Bleeding complications with the use of frequent criticisms associated with coil PED device are estimated to be 1.75%, with of Embolization therapy are high rate of 0.75% morbidity and approximately aneurysm recurrence after treatment, 1%mortality [1, 8]. Among the most frequent incomplete occlusion and the presence of complications include ipsilateral parenchymal remnants of the aneurysm [6]. hemorrhage and subarachnoid hemorrhage Description of Flow Diverters: [1]. Complications usually occur between 2- The pipeline embolization device (PED) is 135 days after implantation of the device [1]. a mesh made tube like, composed of platinum The inflow of blood in the residual (25%) and rest 75% of the alloy of cobalt and aneurysm during post-implantation is nickels (Fig. 1) [1, 11]. It can provides a considered a risk factor [1]. Furthermore, coverage of 30-35% of the vessel in question leukocytes contained in the process of and the common diameter of pore is 0.02 to 0.5 thrombus formation, activity of lytic enzymes mm2 [1, 14]. The coverage area provided by such as elastase with increased activity and the PED is about three times of intracranial presence in the thrombi of red blood cells in stent [1, 11]. Once the device is positioned white cell; which leave an organized formation through the segment of the aneurysm is of these thrombi [15] which could explain the released, beginning to expand and rotate for subsequent breaking of intracranial clockwise [1]. aneurysms [1]. Wan et al. reported three Flow Diverters with a low degree of patients treated with Flow Diverters which porosity but a high pore density can achieving showed massive stroke after device a further reduction of flow within the implantation and bleeding during the aneurysm sac [3, 4, 5, 10, 11]. The blood flow procedure [2]. into the aneurysm is influenced by the Thromboembolic complications: geometry, the surrounding vasculature, the Among the most frequent risks of size and position of the aneurysm [4, 9, and endovascular treatment the hemorrhagic 13]. The aneurysm diameter also plays a very aneurysm rupture is among them, important role in predicting a possible rupture intraoperative and postoperative level [7]. of intracranial aneurysm [4, 9, and 13]. The Thromboembolic complications are much theoretical advantage of this technique is based more common [7]. The frequency of on reconstruction of the main vessel, thromboembolic complications may vary, it thrombosis of aneurysm sac of any was 7% in unruptured aneurysms cases in the morphology regardless of the aneurysm neck 470 | Zenteno et al - Flow diverter device failure ATHENA study by and in 12.5% of cases before shifting the patient to surgery [7]. Doses showed thromboembolic complications e of 70-80 U / kg have been proposed in CLARITY study [7]. Morbidity and mortality protocols using heparin in cardiac care occurred in 3.8% of cases [7]. The stents use obtaining an effective anticoagulation [7]. leads to increase in the perioperative stroke After administration of boluses of 70 U / kg risk and usually occurs within the first 48 continues with an adjustment in the dose of postoperative hours in 10% of cases [7]. The 18U / kg