Therapeutic Occlusion Research Articles

Complex paraclinoidal and giant cavernous aneurysms: importance of preoperative evaluation with temporary balloon occlusion test and SPECT

In the treatment of complex paraclinoidal and giant cavernous aneurysms, preservation of the patency of the internal carotid artery (ICA) is not always possible, and therapeutic occlusion of the carotid is still an important option for their management. A complete preoperative evaluation of the carotid reserve circulation, including the use of temporary balloon occlusion test and single photon emission computerized tomography (SPECT) should be included in the current paradigms of paraclinoidal and intracavernous aneurysms management. We present a series of fifteen patients with sixteen giant or complex carotid cavernous or ophthalmic aneurysms that were treated following a protocol for our preoperative decision-making analysis. Extracranial to intracranial saphenous vein bypass was reserved to the cases where carotid occlusion would be associated with high risk of ischemic complications and was performed in three patients. Besides the difficulties in dealing with those complex aneurysms, good clinical outcome was possible in our experience with the designed paradigm.

Long term evaluation of brain perfusion with magnetic resonance in high flow extracranial-intracranial saphenous graft bypass

Assessment was made of the cerebral vascular haemodynamic parameters in patients with a high-flow extra-intracranial (EC-IC) bypass performed for therapeutic occlusion of the internal carotid artery (ICA). Sixteen patients with ICA occlusion and EC-IC bypass (time interval from surgery 1-6 years) underwent MRI. Perfusion-weighted magnetic resonance imaging (PW-MRI) sequences were performed without the use of an arterial input function. The relative cerebral blood volume (rCBV), mean transit time (MTT) and relative cerebral blood flow (rCBF) were evaluated in all patients at the level of the basal ganglia, centrum semiovale and cortex in both hemispheres. Statistically significant differences (P<0.005) were observed in the haemodynamic parameters, indicating increased rCBV in the basal ganglia and decreased rCBF and rCBV in the cortex of the hemisphere supplied by the graft with respect to the contralateral. Patients with occlusion of the ICA and high flow EC-IC bypass do have altered vascular haemodynamic status between the hemispheres. In particular, rCBF is impaired in the surgical hemisphere at the level of the cortex. These patients should be followed-up to rule out chronic ischemia.

Revascularization and Parent Artery Occlusion for Giant Internal Carotid Artery Aneurysms in the Intracavernous Portion Using Intraoperative Monitoring of Cerebral Hemodynamics

Therapeutic parent artery occlusion with or without revascularization is a useful surgical technique for the management of a giant aneurysm located in the intracavernous portion of the internal carotid artery (ICA). The purpose of the present study was to determine whether intraoperative cortical blood flow (CoBF) monitoring during surgical parent artery occlusion could identify patients who required bypass with a saphenous vein graft (high flow bypass). Eleven patients with a giant aneurysm located in the intracavernous portion of the ICA underwent superficial temporal artery-middle cerebral artery bypass. CoBF was monitored intraoperatively in all patients using a thermal diffusion flow probe. The lowest CoBF during test occlusion of the ICA under functioning superficial temporal artery-middle cerebral artery bypass was determined, and the ratio of the value to the CoBF immediately before test occlusion of the ICA was calculated in the frontal and temporal lobes. When the CoBF ratio in the frontal or temporal lobe was less than 0.9, high flow bypass grafting was elected. Of the eleven patients undergoing superficial temporal artery-middle cerebral artery bypass, five patients underwent concomitant high flow bypass grafting. Postoperative cerebral ischemic events did not occur in any patient over a follow-up period ranging from 3 to 60 months. Postoperative cerebral angiography showed resolution of the aneurysm and patency of the bypass in all patients. Intraoperative CoBF monitoring using a thermal diffusion flow probe during surgical parent artery occlusion for giant intracavernous carotid artery aneurysms can identify patients who require concomitant high flow bypass grafting.

Balloon Test Occlusion with Perfusion CT Imaging Utilizing Intraarterial Contrast Injection

Balloon Test Occlusion (BTO) is performed to evaluate the collateral flow when a permanent therapeutic occlusion of unilateral carotid artery is planned. BTO with neurological evaluation alone, however, has a rather high false negative rate. In order to improve the sensitivity, several adjunctive procedures such as induced hypotension or cerebral blood flow (CBF) measurement with various modalities have been combined. Perfusion CT (PCT) is another imaging modality that is mainly used for the diagnosis of acute stroke. In this study, we evaluate the efficacy and the safety of BTO combined with PCT in the same procedure utilizing intraarterial contrast injection from the catheter. Seven patients underwent BTO with PCT in our institution. All the procedures were performed in the angio/CT combination suite. BTO was performed in the usual fashion and when the patient passed the 30 minutes' BTO clinically, PCT was performed subsequently. Contrast material was injected from a Pig Tail catheter placed in the ascending aorta. The obtained data were transferred to a workstation and perfusion maps of CBF, cerebral blood volume (CBV), and time to peak (TTP) were generated using software. In three patients, single photon emission CT (SPECT) was also obtained with administering 99 mTc-ethyl cysteinate dimer (99 mTc-ECD) intravenously during BTO. Although all the patients had passed the BTO clinically, the CBF maps of three patients revealed significant decrease in the occluded hemisphere. There was no procedure-related morbidity. PCT using intraarterial contrast injection during BTO was performed successfully and safely. Intraarterial injection allowed us to obtain excellent time-attenuation curves by utilizing less contrast material and less radiation doze.

Cerebral Perfusion Imaging

There are multiple imaging techniques available to assess cerebral perfusion, including positron emission tomography (PET), xenon computed tomography (XeCT), single photon emission computed tomography (SPECT), perfusion-weighted MRI (PWI), and perfusion computed tomography (PCT). Current interest has focused mainly on their use in the setting of acute brain ischemia. Perfusion imaging may be able to distinguish infarcted from salvageable ischemic tissue as a guide to treatment. Perfusion techniques may also be helpful in cases of chronic ischemia, post-subarachnoid hemorrhage vasospasm, trauma, and contemplated therapeutic carotid artery occlusion.

Why “Neuroendovascular Surgery”?

Why “Neuroendovascular Surgery”?

Therapeutic Occlusion of an Internal Carotid Artery with a High-Grade Stenosis Using Guglielmi Detachable Coils

We present a patient with a symptomatic, high-grade stenosis of the internal carotid artery (ICA) and contraindication for open surgery. Endovascular treatment was attempted, but stent placement was not possible. In view of good collateral flow to the related hemisphere, embolization of the stenosis of the ICA with Guglielmi detachable coils (GDCs) was performed to occlude the vessel. No complications occurred during the procedure or in the 1-year follow-up period. In cases where open surgery or endovascular treatment of a stenosis of the ICA are contraindicated or not possible, therapeutic occlusion of the stenotic ICA could be an alternative treatment option in patients with good collateral flow.

Treatment of a Sequential Giant Fusiform Aneurysm of the Basilar Trunk

We report an exceptional case of a de novo giant fusiform aneurysm of the basilar trunk, which developed shortly after the therapeutic occlusion of the right internal carotid artery for a fusiform carotid aneurysm. It would appear to be appropriate to call this entity a sequential giant fusiform aneurysm. The patient was successfully treated with endovascular occlusion of the giant basilar trunk aneurysm following bypass surgery.

Regional dyssynergy of the interventricular septum after septal artery occlusion in hypertrophic obstructive cardiomyopathy: use of quantitative Doppler tissue and strain rate imaging

We report the regional myocardial mechanics of the interventricular septum in a patient with hypertrophic obstructive cardiomyopathy undergoing therapeutic septal artery occlusion. Myocardial velocities improved across the entire septum; however, strain rate imaging showed the presence of severe regional dyssynergy.

Multi-slice CT angiography in evaluation of extracranial–intracranial bypass

Multi-slice CT (MSCT) scanners provided significant improvement in vascular applications. In this study, our purpose was to determine the clinical utility of MSCTA in evaluation of extracranial–intracranial (EC-IC) bypass patency. Eleven (4 men and 7 women; mean age, 46 years; age range, 19–68 years) consecutive patients who underwent MSCTA and DSA after EC-IC bypass surgery were evaluated retrospectively. All patients underwent DSA within 3 weeks of MSCTA. The indications for EC-IC bypass were severe stenosis or occlusion of intracranial arteries in seven patients and therapeutic occlusion of intracranial artery for unclippable giant aneurysm in four patients. Ten patients underwent superficial temporal artery (STA)–middle cerebral artery (MCA) bypass and one patient underwent occipital artery–posterior cerebral artery (PCA) bypass. Eight STA–MCA bypasses in six patients were patent on MSCTA which were confirmed on DSA. Two STA–MCA bypasses and one occipital artery–posterior cerebral artery (PCA) bypass were occluded in three patients on MSCTA and DSA. In one patient, minimal stenosis of the STA–MCA bypass was identified on MSCTA and DSA. In 1 patient, STA–MCA bypass was not well seen on MSCTA and suspected for occlusion. DSA identified the occlusion of bypass on this patient. MSCTA seems to be a very promising noninvasive technique in evaluation of EC-IC bypass.

An approach to targeted drug delivery based on uniform magnetic fields

The capability to deliver high effective dosages to specific sites in the human body has become the holy grail of drug delivery research. Drugs with proven effectiveness under in vitro investigation often reach a major roadblock under in vivo testing due to a lack of an effective delivery strategy. In addition, many clinical scenarios require delivery of agents that are therapeutic at the desired delivery point, but otherwise systemically toxic. We propose a method for targeted drug delivery by applying uniform magnetic fields to an injected superparamagnetic colloidal fluid carrying a drug. The experimental and theoretical models presented give insight into the use of magnetic microspheres for site-specific delivery of therapeutic agents and blood flow occlusion for embolotherapy.

Early Intracerebral Hemorrhage Complicating the Successful Occlusion of a Carotid-Cavernous Fistula

A 74-year-old woman with a direct carotidcavernous fistula secondary to aneurysm rupture was treated by endovascular balloon occlusion of the fistula. Two days later, she suffered an intracerebral hemorrhage ipsilateral to the treated carotid cavernous fistula, perhaps due to normal perfusion pressure breakthrough. Normal perfusion pressure breakthrough has been described as a cause of hemorrhage following treatment of arteriovenous malformations (1) and carotid stenosis (2,3). We report an unusual case of therapeutic endovascular occlusion of a direct carotid-cavernous fistula complicated by hemorrhage presumably caused by normal pressure perfusion breakthrough.

Therapeutic cardiac catheterization for congenital heart disease—a new era in pediatric care

In recent years, enormous technological advances have occurred that allow intervention for many congenital heart defects in the pediatric cardiac catheterization laboratory. Therapeutic catheterization procedures, including valvuloplasty, angioplasty, stent implantation, coil embolization, and device occlusion, are employed to treat heart defects in infants and children. This report describes these interventional procedures, outcomes, potential complications, and implications for nursing care. Copyright © 2001 W.B. Saunders Company

Cerebral Revascularization for Cerebral Ischemia and Stroke Prevention in Patients with Atherosclerotic Occlusive Disease: Defining the Population That Benefits

The decision to perform a revascularization procedure on a patient who may or may not benefit from it must be based on an understanding of the impact of spontaneous or therapeutic vascular occlusion on the physiologic, by which the cerebral circulation compensates for vascular occlusions. This impact is patient specific and requires examination of a number of possible physiologic parameters.

Angiographic Findings and Clinical Significance of the Anterior and Posterior Spinal Arteries in Therapeutic Parent Artery Occlusion for Vertebral Artery Aneurysms

Three of 16 patients with vertebral artery (VA) aneurysms treated by parent artery occlusion suffered ischemic complications. The cause of the ischemic complications was brain stem or upper cervical spinal cord infarction due to occlusion of the anterior spinal artery (ASA), posterior spinal artery (PSA) and perforating arteries arising from the VA. Angiographic detection of ASA and PSA was studied in 71 consecutive patients (142 VAs) with various diseases who underwent digital subtraction angiography. The ASA and PSA originated from the bilateral VAs in 14% and 9%, unilateral VA in 73% and 35%, and were not detected in 13% and 56%, respectively. These results indicate that the rate of angiographic detection of the ASA originating from the bilateral VAs is considerably lower than that of previously reported anatomical studies. Special attention must be paid to the ASA, PSA and perforating arteries on preoperative vertebral angiography to prevent ischemic complications associated with therapeutic parent artery occlusion for VA aneurysms.

クリッピング困難な椎骨動脈瘤に対する治療選択

Therapeutic occlusion of the vertebral artery (VA) is considered a treatment of choice for unclippable vertebral artery aneurysms and can be achieved with surgical or endovascular intervention. To avoid ischemic complications after treatment, the location and extent of obliteration must be carefully planned. We describe 3 cases of unclippable vertebral artery aneurysms and discuss proper therapeutic options for patients with various vascular structures. Risk of ischemic complications depends on two factors: location of the aneurysm, and the origin of the posterior inferior cerebellar artery (PICA). If an aneurysm is near the vertebral junction and PICA originates at a low position, the perforators probably arise from the long segment between these two structures. VA occlusion above the PICA may cause thrombosis at the stump end of the VA, which would affect the perforators. In this situation, the VA should be occluded below the PICA to avoid subsequent ischemia in the brainstem. The anterior spinal artery, another vital branch from the VA and sometimes visualized on angiogram, should also be preserved. A temporary balloon test occlusion of the VA is a useful adjunct to predict tolerance for ischemia in the basilar artery territory.

ENDOVASCULAR THERAPY OF TRAUMATIC INJURIES OF THE INTRACRANIAL CEREBRAL ARTERIES

Traumatic intracranial arterial injuries represent uncommon complications of both closed-head injury and penetrating head trauma. These injuries include arterial dissections, pseudoaneurysms, and fistulas, both direct and indirect. Although these lesions may be identified while still asymptomatic, they usually present in a delayed fashion with intracranial hemorrhage, focal cerebral ischemia, or, occasionally, severe epistaxis. Endovascular therapy has assumed a major role in the management of this diverse group of lesions. Embolization of pseudoaneurysms with balloons or detachable coils, the use of embolic particles for small arterial injuries, and large vessel occlusion with detachable balloons represent current treatment strategies that have evolved over the past three decades. Angioplasty and stent deployment may have a future role to play in the management of arterial dissection. Principles of neurologic critical care that minimize secondary brain injury are essential adjuncts in the management of these patients before, during, and after endovascular treatment.

Simulation of therapeutic parent artery occlusion for basilar head aneurysms. Hemodynamic effect of occlusion sites and diameters of collateral arteries

We simulated parent artery occlusion therapy for basilar head aneurysms to elucidate the hemodynamic changes induced by different occlusion sites and diameters of the posterior communicating arteries (PCom) as collateral pathways. A vascular model of the vertebrobasilar system with a basilar head aneurysm was constructed. Four types of occlusion were simulated: Basilar artery occlusion distal to (Type A)I between (Type B) and proximal to (Type C) the superior cerebellar arteriesl and bilateral vertebral artery occlusion (Type D). Glycerol solution was perfused into the modell and the half-life of the dye injected into the aneurysm was calculated and regarded as an index of stagnant flow in the aneurysm. The half-life was increased ~ignificantly and nonlinearly after parent artery occlusionl depending on the occlusion site and the ratio of two PCom diameters (diameter ratio). Intra-aneurysmal stagnation developed markedly in Type A and Type B in the diameter ratio higher than 0.70 and considerably in Type C in the ratio higher than 0.80. Additional P1 occlusion of the posterior cerebral artery enhanced the stagnation in Type A and B. Since the results are consistent with the published clinical datal the simulation study will be useful for speculating the efficacy of the therapeutic occlusion. [Neurol Res 1999; 21: 180-184]

Effect of internal maxillary arterial occlusion on nasal blood flow in swine.

The precise effects of therapeutic occlusion of the internal maxillary artery (IMA) on distal nasal mucosal perfusion are unknown. A better understanding of these effects has important implications regarding the rationale and expected efficacy of certain therapeutic interventions for epistaxis management. The authors developed an animal model to assess these issues. The effects of "proximal" and progressively more "distal" occlusions of the IMA on nasal mucosal blood flow (NBF) were assessed in anesthetized swine using continuous laser Doppler flowmetry. The levels of arterial occlusion were selected to simulate clinical therapeutic occlusions used for the management of epistaxis. Nineteen swine were entered into one of four experimental groupings: proximal IMA occlusion using platinum micro-coils (n = 6), mid-grade distal IMA occlusion with polyvinyl alcohol particulate (PVA) suspensions (300 to 500 microns, n = 5), high-grade distal IMA occlusion with polyvinyl alcohol particulate suspensions (50 to 150 microns, n = 5), and sham control (n = 2). All embolizations resulted in acute decreases in average NBF from 120 mL/min per 100 g to 40 mL/min per 100 g (P < .05 for all groups). NBF returned to baseline in all three treated groups within 2 to 8 days after therapeutic embolization, depending on the level of occlusion (coils, 2 d; mid-grade PVA, 2-3 d; high-grade PVA, 8 d). Follow-up angiography showed recanalization and collateralization as possible methods of reestablishing NBF. This study supports the rationale for performing distal IMA occlusion with transarterial particulate embolization, in order to provide a longer period of time of diminished NBF. This theoretically should promote hemostasis within an injured portion of the nasal mucosa by decreasing perfusion pressure within the capillary bed. However, the benefits of distal IMA embolization must be balanced against potential ischemic complications, as may be more commonly seen with high-grade particulate embolization.

Failure of the hypotensive provocative test during temporary balloon test occlusion of the internal carotid artery to predict delayed hemodynamic ischemia after therapeutic carotid occlusion

BACKGROUND Extensive experience and critical evaluation of the efficacy of a pharmacologic hypotensive challenge during conventional balloon test occlusion (BTO) of the internal carotid artery (ICA) is lacking. This prompted us to review our institution’s most recent experience with this adjunctive provocative test before planned therapeutic balloon occlusion of the ICA. METHODS Twenty consecutive cases of endovascular therapeutic balloon occlusion of the ICA were retrospectively reviewed. Conventional BTO under normotension and with hypotensive challenge were performed within a standardized protocol. RESULTS Sixteen patients underwent provocative testing, of which 13 had BTO with hypotensive challenge. All patients in this group tolerated these maneuvers without acute neurologic deficit. Two (15%) of these patients developed delayed permanent neurologic deficits, which seemed to be attributable to hemodynamic ischemia. One of seven patients not undergoing hypotensive challenge also developed transient neurologic deficits after carotid occlusion. CONCLUSIONS Despite the conceptually attractive and early positive experience of the hypotensive challenge in attempting to increase sensitivity and specificity of risk for developing delayed hemodynamic ischemia, we have found two significant false-negative results. This experience is reviewed in the context of risks of permanent balloon occlusion of the carotid artery after balloon test occlusion.