Biomedical subjects
F Viñuela
Publications and source records attributed to F Viñuela.
Intracranial aneurysms treated with the Guglielmi detachable coil: midterm clinical results in a consecutive series of 100 patients.
A prospective study was designed to evaluate clinical outcome in a series of 100 consecutively treated patients who underwent endovascular embolization of 104 intracranial aneurysms using Guglielmi detachable coils (GDCs). Midterm clinical outcome (2-6 years, average 3.5 years) was obtained for 94 patients and was classified according to a modified Glasgow Outcome Scale. Of nine patients treated in the acute phase of severe subarachnoid hemorrhage (Grade IV or V), seven died from the initial hemorrhage, one had a poor outcome, and one had a fair midterm outcome, with no post-GDC embolization hemorrhages. Twenty patients underwent subsequent surgical or endovascular procedures that did not include the use of GDCs. These included aneurysm clipping in nine patients and parent vessel sacrifice in 11 patients. None of these 20 patients experienced post-GDC embolization hemorrhage. The postoperative midterm clinical outcomes of these 20 patients did not significantly differ from the outcomes of patients who underwent GDC embolization as their definitive treatment. Six patients died of unrelated causes prior to reaching the 2-year survival point, with no post-GDC embolization hemorrhage. The midterm outcomes of the remaining 61 patients who underwent GDC embolization as their definitive treatment were classified as excellent (46 patients [75%]), good (seven patients [11%]), fair (three patients [5%]), poor (one patient [2%]), or dead (four patients [7%]). All four patients died from giant lesions. At midterm follow up, the surviving 57 patients' neurological statuses were unchanged or improved in 54 cases and worsened in three cases. The midterm post-GDC embolization hemorrhage rate was 0% for small aneurysms, 4% (one case) for large aneurysms, and 33% (five cases) for giant lesions. The GDC procedure is a safe, effective, and reliable means of preventing aneurysm hemorrhage in patients with small and large intracranial aneurysms. Results, however, are less satisfactory in cases involving giant lesions. Further follow-up review is necessary to establish durability in the longer term. Patients with Grade IV or V subarachnoid hemorrhage in this series generally had poor outcomes even if the GDC procedure was successful in occluding the aneurysm.
Incidence of cerebral vasospasm after endovascular treatment of acutely ruptured aneurysms: report on 69 cases.
Cerebral vasospasm is the most common cause of morbidity and mortality in patients admitted to the hospital after suffering aneurysmal subarachnoid hemorrhage (SAH). The early surgical removal of subarachnoid clots and irrigation of the basal cisterns have been reported to reduce the incidence of vasospasm. In contrast to surgery, the endovascular treatment of aneurysms does not allow removal of subarachnoid clots. In this study the authors measured the incidence of symptomatic vasospasm after early endovascular treatment of acutely ruptured aneurysms with Guglielmi detachable coils (GDCs). Sixty-nine patients classified as Hunt and Hess Grades I to III underwent occlusion of intracranial aneurysms via GDCs within 72 hours of rupture. The amount of blood on the initial computerized tomography (CT) scan was classified by means of Fisher's scale. Symptomatic vasospasm was defined as the onset of neurological deterioration verified with angiographic or transcranial Doppler studies. Hypertensive, hypervolemic, hemodilution therapy, with or without intracranial angioplasty, was used to treat vasospasm after GDC placement. Symptomatic vasospasm occurred in 16 (23%) of 69 patients. The clinical grade at admission and the amount of blood on the initial CT were both associated with the incidence of subsequent vasospasm. At 6-month clinical follow-up examination, 12 of these 16 patients experienced a good recovery, two were moderately disabled, and two patients had died of vasospasm. In conclusion, the 23% incidence of symptomatic vasospasm in this series compares favorably with that found in conventional surgical series of patients with acute aneurysmal SAH. These results indicate that endovascular therapy does not have an unfavorable impact on cerebral vasospasm.
Embolization of dural cavernous fistulas via superior ophthalmic vein approach.
PURPOSE: To present the results of our treatment of dural cavernous sinus fistulas with surgical exposure of the superior ophthalmic vein (SOV), retrograde venous catheterization, and coil embolization of the cavernous sinus. METHODS: Twelve patients with dural cavernous sinus fistulas were treated via a retrograde transvenous SOV approach in our hospital during a 3-year period. All patients had been referred by ophthalmologists because of secondary glaucoma and decreased visual acuity. Angiography showed preferential venous drainage of the dural cavernous sinus fistulas to an enlarged ipsilateral SOV. A total of 13 SOV exposures were performed, one patient with bilateral fistulas required bilateral treatment. The vein was surgically exposed by an ophthalmologist and then catheterized. Platinum coils were delivered through a microcatheter at the fistula site and into the root of the SOV, until there was complete angiographic closure. RESULTS: Catheterization and embolization were successful in 12 of the 13 patients, with complete angiographic occlusion of the fistula. Two patients with bilateral fistulas had transient worsening of symptoms on the contralateral side. Three patients required follow-up angiography. No early complications occurred, and late complications were minor in two cases. All patients except one with long-standing symptoms recovered premorbid visual acuity. At follow-up, 11 (92%) of the 12 embolized fistulas remained occluded. CONCLUSIONS: Retrograde catheterization of the SOV and embolization of the cavernous sinus with coils is a direct, safe, and efficient way to occlude dural cavernous sinus fistulas.
[Myelographic diagnosis of an epidural arterio-venous fistula].
INTRODUCTION: Epidural arterio-venous fistulae are a little known clinical condition. They are probably commoner than is thought, since diagnosis and angiographic demonstration are difficult. CLINICAL CASE: We present the case of a 49 year old man with the clinical features of chronic myelo-radiculopathy with episodes of intermittent medullary claudication. This shows the use of myelography, which in certain cases allows clear detection of vascular structures which might otherwise pass unnoticed. CONCLUSIONS: One should think of this condition when compatible features are found and there is no other diagnosis, since if confirmed by myelography and/or magnetic resonance prior to angiographic study, it may benefit from embolization, which is an effective treatment for this.
A biomathematical model of intracranial arteriovenous malformations based on electrical network analysis: theory and hemodynamics.
Hemodynamics play a significant role in the propensity of intracranial arteriovenous malformations (AVMs) to hemorrhage and in influencing both therapeutic strategies and their complications. AVM hemodynamics are difficult to quantitate, particularly within or in close proximity to the nidus. Biomathematical models represent a theoretical method of investigating AVM hemodynamics but currently provide limited information because of the simplicity of simulated anatomic and physiological characteristics in available models. Our purpose was to develop a new detailed biomathematical model in which the morphological, biophysical, and hemodynamic characteristics of an intracranial AVM are replicated more faithfully. The technique of electrical network analysis was used to construct the biomathematical AVM model to provide an accurate rendering of transnidal and intranidal hemodynamics. The model represented a complex, noncompartmentalized AVM with 4 arterial feeders (with simulated pial and transdural supply), 2 draining veins, and a nidus consisting of 28 interconnecting plexiform and fistulous components. Simulated vessel radii were defined as observed in human AVMs. Common values were assigned for normal systemic arterial pressure, arterial feeder pressures, draining vein pressures, and central venous pressure. Using an electrical analogy of Ohm's law, flow was determined based on Poiseuille's law given the aforementioned pressures and resistances of each nidus vessel. Circuit analysis of the AVM vasculature based on the conservation of flow and voltage revealed the flow rate through each vessel in the AVM network. Once the flow rate was established, the velocity, the intravascular pressure gradient, and the wall shear stress were determined. Total volumetric flow through the AVM was 814 ml/min. Hemodynamic analysis of the AVM showed increased flow rate, flow velocity, and wall shear stress through the fistulous component. The intranidal flow rate varied from 5.5 to 57.0 ml/min with and average of 31.3 ml/min for the plexiform vessels and from 595.1 to 640.1 ml/min with an average of 617.6 ml/min for the fistulous component. The blood flow velocity through the AVM nidus ranged from 11.7 to 121.1 cm/s with an average of 66.4 cm/s for the plexiform vessels and from 446.9 to 480 dyne/cm2 with an average of 463.5 dyne/cm2 for the fistulous component. The wall shear stress ranged in magnitude from 33.2 to 342.1 dyne/cm2 with an average of 187.7 dyne/cm2 for the plexiform vessels and from 315.9 to 339.7 cm/s with an average of 327.8 cm/s for the fistulous component. The described novel biomathematical model characterizes the transnidal and intranidal hemodynamics of an intracranial AVM more accurately than was possible previously. This model should serve as a useful research tool for further theoretical investigations of intracranial AVMs and their hemodynamic sequelae.
Endovascular embolization of superior hypophyseal artery aneurysms.
OBJECTIVE: Internal carotid artery aneurysms arising from the superior hypophyseal artery are frequently termed paraophthalmic or paraclinoid aneurysms, but they constitute a distinct anatomic entity. They are particularly amenable to endovascular treatment. METHODS: Between 1991 and 1995, we attempted treatment in 11 patients with superior hypophyseal artery aneurysms with Guglielmi detachable coil embolization and were successful in 10. Surgical exploration in seven of the patients was unsuccessful, three patients were considered to be at high risk for surgery or to have poor likelihood of surgical success by the referring neurosurgeon, and one patient refused operative clipping. Two aneurysms were giant (> 25 mm), three were large (10-25 mm), and six were small (< 10 mm). Of the six small aneurysms, two had wide necks (> 4 mm) and four had narrow necks (< or = 4 mm). RESULTS: There were no technical or clinical complications related to embolization. Immediate complete aneurysm obliteration was obtained in five aneurysms, all of which were small. Four of the remaining five aneurysms had obliteration of the dome and body, leaving only a small remnant neck. The remaining semifusiform aneurysm represented our single treatment failure. Recanalization occurred in only one patient; that patient had a giant aneurysm. Nine of the 10 patients for whom embolization was successful had good or excellent clinical outcomes; there were no clinical deteriorations attributable to embolization. CONCLUSION: We conclude that Guglielmi detachable coil embolization of superior hypophyseal artery aneurysms is an excellent treatment alternative, especially for smaller lesions.
Transvenous hemodynamic assessment of experimental arteriovenous malformations. Doppler guidewire monitoring of embolotherapy in a swine model.
BACKGROUND AND PURPOSE: A Doppler guidewire was used to monitor progressive changes in draining vein flow parameters during experimental embolotherapy in a swine arteriovenous malformation (AVM) model. METHODS: A microcatheter was positioned superselectively in the main arterial feeder and main draining vein in each of 10 AVM models in swine. With use of the Doppler guidewire, preembolization arterial and venous average peak velocities (APVs) and pulsatility indices were recorded. The device was left in the draining vein during transarterial particulate (in 8 swine) or liquid adhesive (in 2 swine) embolization, and continuous transvenous flow during and after treatment was monitored. Periembolization Doppler flow parameters were correlated qualitatively with angiographic changes in the nidus. RESULTS: Preembolization draining vein flow was pulsatile, with a mean APV of 38.9 +/- 13.7 cm/s. After embolization, this changed significantly to a less pulsatile or nonpulsatile pattern, with a lower mean APV of 9.2 +/- 4.9 cm/s (P = .0001). A novel expression, the maximum minus the minimum peak velocity (MxPV-MnPV), was used in evaluating the transvenous Doppler spectra. This was reduced significantly after embolization from a mean of 11.1 +/- 3.5 cm/s to 6.7 +/- 2.5 cm/s (P = .0025). Objective periembolization hemodynamic changes were detected in the draining veins earlier than the visually subjective angiographic changes within the nidus. CONCLUSIONS: Transvenous Doppler guidewire assessment of two parameters, APV and MxPV-MnPV, is useful in the hemodynamic evaluation of experimental arteriovenous shunting and may be used for future objective and quantitative monitoring during endovascular AVM embolotherapy.
Treatment of large and giant fusiform intracranial aneurysms with Guglielmi detachable coils.
Results in nine patients with large or giant fusiform intracranial aneurysms that were treated with Guglielmi detachable coils (GDCs) are reported. There were six males and three females between the ages of 12 and 63. Four patients presented with subarachnoid hemorrhage (SAH) and four with mass effect; in one patient the aneurysm was asymptomatic and located in an arterial feeder of an arteriovenous malformation. Five aneurysms were supratentorial and four were in the posterior fossa. Five were giant and four were large. Selective occlusion with preservation of the parent artery was attempted in three cases, and complete occlusion of the aneurysm and the parent artery was performed in six patients. The tolerance to parent artery occlusion was assessed by angiography, balloon test occlusion, and amytal testing. Six aneurysms were permanently occluded and two partially recanalized. In one case, GDC embolization was not possible. The four patients who presented with SAH made an excellent clinical recovery. Three of the four patients presenting with mass effect recovered completely and one remained unchanged. The patient with an incidental aneurysm remained asymptomatic. There were no permanent complications. In conclusion, GDCs were useful for the occlusion of large and giant intradural fusiform aneurysms. Occlusion of the aneurysm and the parent artery afforded the greatest opportunity for a complete cure. Advantages of GDCs compared to balloons include: occlusion of a shorter segment of normal artery, no traction on the parent vessel, and safer and easier catheterization techniques.
Endovascular treatment of multiple aneurysms involving the posterior intracranial circulation.
The results of surgery on multiple intracranial aneurysms tha involve the vertebrobasilar circulation are poor, and associated patient mortality remains high. We describe the endovascular treatment of four patients with mutiple aneurysms that involved the posterior intracrancial circulation. Satisfactory occlusion of all aneurysms was achieved by using electrolytically detachable coils, and all patients had a good clinical recovery. Our early experience suggests that endovascular coil occlusion may be a particularly suitable method for treating this high-risk condition.
Arteriovenous malformation animal model for radiosurgery: the rete mirabile.
PURPOSE: To study the effects of single-dose radiation on the porcine rete mirabile, a tangle of microvessels that mimics human arteriovenous malformations of the brain. METHODS: Eight retia mirabilia received a single dose of radiation under stereotactic location with digital angiography and CT. The following doses were applied: 20, 30, 40, 50, 60, 70, 80, and 90 Gy. The animals were followed up for a period of 7 months. Findings at neurologic examination, serial angiography, and histopathologic examination were analyzed. RESULTS: Progressive occlusion as observed by angiography corresponded to the histopathologic finding of intimal hyperplasia; that is, marked thickening of the vessel wall, progressing to occlusion of the vascular lumen, and associated thrombosis. A direct dose response was noted for these changes. Neurologic findings were related to the dose distribution and to histologic findings in structures adjacent to the rete mirabile. CONCLUSION: The rete mirabile is an excellent model by which to study the radiologic and histologic effects of single-dose radiation to the microvasculature of the central nervous system.
Endovascular treatment of arteriovenous malformations with selective intranidal occlusion by detachable platinum electrodes: technical feasibility in a swine model.
The technical feasibility of selective intranidal endovascular occlusion of experimental arteriovenous malformations with detachable superfine platinum electrodes was assessed in a swine model. The delivery and release of electrodes were performed within normal carotid retia mirabilia, the faster-flowing nidus (bilateral retia) of a carotid-jugular fistula-type model of an arteriovenous malformation, and a small-caliber H-type direct arteriovenous fistula. Controllable atraumatic placement of the electrodes was possible deep within each rete and in the middle of the fistula. The devices were soft and flexible, allowing them to conform to the tight turns and branches of rete vessels. Marked diminution of flow was achieved by release of multiple devices within each rete. Migration of the electrode occurred when detached within the larger-caliber arteriovenous fistula. The main advantages of this technique appear to be the controlled delivery and assured release of an occlusive radiopaque embolic agent within the nidus.
Correlation of the angioarchitectural features of cerebral arteriovenous malformations with clinical presentation of hemorrhage.
Superselective angiography is the most accurate technique in the analysis of brain arteriovenous malformation (AVM) angioarchitecture. Therefore, we reviewed the selective and superselective angiograms of 100 consecutive patients with intracerebral AVMs. Our purpose was to determine which parameters of angioarchitecture were significantly correlated with a clinical presentation of hemorrhage. The vascular characteristics evaluated on the angiograms were the size of the AVM, the location of the AVM, the type of nidus, the type of feeders, the characteristics of venous drainage, and the number and location of aneurysms. The parameters found to correlate with hemorrhage were deep venous drainage (P = 0.01), feeding by perforators (P = 0.01), intranidal aneurysm(s) (P = 0.004), multiple aneurysms (P = 0.001), feeding by the vertebrobasilar system (P = 0.002), and location in the basal ganglia (P = 0.04). Six parameters of AVM angioarchitecture were correlated with a clinical presentation of hemorrhage. Among these parameters, three (feeding by perforators, number of aneurysms, and presence of intranidal aneurysms) were well displayed by superselective angiogram.
Aneurysm rupture after parent vessel sacrifice: treatment with Guglielmi detachable coil embolization via retrograde catheterization: case report.
We report a patient with rupture of a giant distal vertebral artery aneurysm after balloon occlusion of the parent vertebral artery. We were able to occlude the residual lumen by endosaccular embolization and trapping with Guglielmi detachable coils via the anterior circulation. We suspect that either alterations in flow patterns or partial thrombosis of the aneurysm may have contributed to at least two subarachnoid hemorrhages within 2 days after the initial embolization. We still considered endovascular parent vessel sacrifice to be an excellent therapeutic option, particularly in distal vertebral aneurysms. We recommend a detailed evaluation of angiographic flow patterns and aneurysm patency during test occlusion. If the aneurysm continues to fill from the collateral circulation, or if marked alterations in flow patterns are present, aneurysm trapping or concurrent endosaccular embolization and parent vessel sacrifice may be necessary. Certainly, continued surveillance is required as long as any residual aneurysm is present.
Neurosurgical management of cerebral aneurysms following unsuccessful or incomplete endovascular embolization.
Modern endovascular techniques permit treatment of intracranial aneurysms in many circumstances when surgery is associated with significant morbidity. Occasionally, embolization of aneurysms is unsuccessful or incomplete or followed by complications, in which case surgical management is required. Since 1986, 196 patients have undergone embolization of intracranial aneurysms at the authors' institution and 21 (11%) required subsequent surgical treatment. Attempted embolization failed in five patients (Group A). Ten patients (Group B) had only partial occlusion of the aneurysm or demonstrated recanalization on follow-up studies. Eight of these Group B patients underwent embolization with Guglielmi detachable coils (GDCs), representing 5.7% of the 141 GDC-treated patients in this experience. Surgical treatment in these two groups consisted of clipping (eight cases), surgical parent vessel occlusion (one case), and parent vessel occlusion with extracranial-intracranial bypass (six cases). Fourteen (93%) of the 15 patients in these two groups had an excellent or good outcome with complete aneurysm occlusion. Six patients underwent surgery to treat complications related to the endovascular procedure (Group C). Of these, four patients had neurological improvement compared to their preoperative state, and two died. This series of cases demonstrates that surgical treatment of aneurysms is usually possible with good results following incomplete embolization and emphasizes the need for close and continued neurosurgical involvement in the endovascular management of intracranial aneurysms.
Acute subdural hemorrhage complicating embolization of a cerebral arteriovenous malformation.
We present a case of a young adult in whom acute subdural hemorrhage developed immediately after embolization of a cerebral arteriovenous malformation with glue. Inadvertent venous outlet obstruction with glue was implicated in the production of the hemorrhage. Possible mechanisms of spread of blood to the subdural space are discussed. Awareness of the possibility of iatrogenic subdural hemorrhage is necessary before undertaking embolization procedures.
Collagen microbeads: experimental evaluation of an embolic agent in the rete mirabile of the swine.
PURPOSE: To evaluate the histologic and angiographic effects of collagen microbeads as an embolic agent in the swine rete mirabile. METHODS: Human collagen particles (380 +/- 100 microns) of spheroidal shape and smooth surface were used to embolize the rete mirabile in five swine. Control angiograms and pathologic examinations were obtained immediately and sequentially from 3 to 35 days after embolization. RESULTS: The collagen particles were easy to inject through microcatheters. Embolization was always angiographically complete and persistent for at least 5 weeks. Histologic studies showed occlusion of 25% to 50% of the rete vessels. After 3 and 5 weeks' follow-up, transmural and adventitial chronic inflammation was present. Inflammatory infiltrates included lymphohistiocytic cells and scattered eosinophils. The foreign-body giant-cell reaction was pronounced. No evidence of angionecrosis or focal hemorrhage was shown. CONCLUSIONS: Collagen microbeads are a promising experimental embolic agent, with potential future applications in humans.
High-flow, small-hole arteriovenous fistulas: treatment with electrodetachable coils.
We present one case of carotid-cavernous fistula caused by percutaneous treatment of trigeminal neuralgia and one case of vertebrovertebral fistula caused by percutaneous internal jugular vein cannulation. Each fistula had a small arteriovenous communication that prevented the use of detachable balloons. Endovascular transarterial treatment of these two iatrogenic fistulas with electrically detachable platinum coils was performed. Both fistulas were occluded with preservation of the parent artery, and the patients have fully recovered.