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Biomedical subjects

G R Duckwiler

Publications and source records attributed to G R Duckwiler.

At least 37 records · Page 2Linked to original sources
PubMed1999

Intraarterial thrombolysis for treatment of acute stroke: experience in 26 patients with long-term follow-up.

BACKGROUND AND PURPOSE: Since the approval of intravenous tissue plasminogen activator for acute ischemic stroke, great interest has been generated in cerebral fibrinolysis. Our purpose was to assess long-term outcome and hemorrhagic risk in patients with anterior circulation ischemic stroke treated with intraarterial urokinase. METHODS: Twenty-six patients were treated within 6 hours of ictus; of these, 21 were followed up for an average of 23 months. Angiographic reperfusion was classified according to thrombolysis in myocardial infarction (TIMI) grades. The Rankin Scale (RS) and the modified Barthel Index (mod BI) were used as outcome measures (good outcome: RS = 0-2, mod BI = 16-20; poor outcome: RS = 3-5, mod BI < or = 15). RESULTS: Ten of the 21 patients (average age, 48 years) had a good outcome; three (average age, 71 years) had a poor outcome; eight patients (average age, 78 years) died. Partial/complete (successful) recanalization was observed in 11 of 26 patients and minimal or no (unsuccessful) recanalization in 15. Recanalization favored a better outcome: nine of 21 had successful recanalization, with a good outcome in seven; 12 of 21 had unsuccessful reperfusion, with poor outcome/death in nine. Poor outcome was noted in five patients with internal carotid artery (ICA) bifurcation occlusions, four of whom had unsuccessful recanalization and poor outcome or death. Hemorrhage occurred in 10 of the 26 patients, with clinical deterioration in three. The average dose of urokinase was higher in the hemorrhage group, and mortality was higher in patients who hemorrhaged. CONCLUSION: Intraarterial thrombolysis is feasible in the setting of acute stroke. Successful reperfusion is associated with a better outcome, and the prevalence of hemorrhage does not exceed that which occurs in the natural history of embolic stroke. Poor outcome or death is associated with nonrecanalization, older age, hemorrhage, and ICA bifurcation occlusions.

Acute Disease↗
PubMed1998

Nonadhesive liquid embolic agent for cerebral arteriovenous malformations: preliminary histopathological studies in swine rete mirabile.

OBJECTIVE: To assess acute and chronic histopathological changes observed in a swine arteriovenous malformation model after endovascular delivery of Embolyx E (Micro Therapeutics Inc., San Clemente, CA) and its organic solvent dimethyl sulfoxide (DMSO). To develop standard endovascular delivery techniques of Embolyx through microcatheters into swine rete mirabile (RMB). METHODS: Forty RMBs in 22 swine were used to analyze acute and chronic angiographic and histological changes after superselective delivery of Embolyx E and/or its organic solvent (DMSO). Four RMBs (two for DMSO and two for Embolyx E study) were used as control specimens. Angiographic and histological evaluations were obtained 18 days, 1 month, 3 months, and 6 months after the procedure. Particular attention was paid to the presence of focal or diffuse angionecrosis, arterial revascularization, and perivascular inflammatory response. RESULTS: Staged and/or continuous delivery of Embolyx E were performed through the DMSO-compatible microcatheters without untoward catheter "gluing." All subacute/chronic specimens embolized with Embolyx E showed no evidence of angiographic recanalization. Twelve RMBs were used in acute studies, and all specimens showed no evidence of angionecrosis or aggressive inflammatory reaction. Subacute and chronic (total, n = 14) histological examinations of the RMBs showed mild inflammatory response manifested by monocellular infiltration and scattered foreign body giant cell reaction. In the 9 of 14 subacute and chronic specimens, focal disruption of elastica was observed along with embolic materials. Fourteen RMBs in eight swine were used to determine the safety range for DMSO injection. Two RMBs were used as control specimens. Rapid intra-arterial delivery (0.5 ml/5-15 s, n = 6) of DMSO caused angiographic vasospasm and histological endothelial necrosis. Slow injection (0.5 ml/30-120 s, n = 8) of DMSO showed minimum or no angiographic vasospasm, minimal adventitial inflammatory response, and no clinical complications. CONCLUSION: Embolyx E, an occlusive and nonadhesive embolic agent, is capable of producing permanent occlusion of swine RMB with the development of mild intra- and perivascular inflammatory changes and no clinical complications. The slow endovascular delivery of DMSO produces no untoward angiographic, pathological, or clinical changes. A fast injection of DMSO causes endothelial necrosis and severe inflammatory response in the arterial wall. This embolic material seems to have appropriate biochemical, anatomic, and histopathological characteristics to be used in the treatment of cerebral arteriovenous malformations or vascular cranial base tumors.

Animals↗
PubMed1998

Direct arteriovenous fistulas (carotid-cavernous and vertebral-venous). Diagnosis and intervention.

Carotid-cavernous and vertebral-venous fistulas are direct arteriovenous fistulas. Their symptoms range from benign to extremely severe ophthalmologic or neurologic complications. Mechanism of symptoms is mostly related to venous drainage. Therapy is widely indicated, as today's endovascular techniques--using mostly detachable balloons and coils--have a high success rate and very few complications.

Arteriovenous Fistula↗
PubMed1997

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.

Acute Disease↗
PubMed1996

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.

Adult↗
PubMed1996

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.

Adult↗
PubMed1996

Laboratory simulations and training in endovascular embolotherapy with a swine arteriovenous malformation model.

We assessed the suitability of a swine experimental arteriovenous malformation model for laboratory simulations and training in endovascular embolotherapy. Embolizations with liquid glue or particles were performed in 10 animals. The parameters of injection (microcatheter position, concentration and volume of embolic agent, injection rate) were deliberately varied to simulate results that may be observed in clinical practice. A range of successful and less desirable therapeutic outcomes or complications was simulated. In one model, intravascular mean blood pressure in the "terminal feeder" rose after "nidus" embolization, consistent with observations in feeders of cerebral arteriovenous malformations. Experience in the technical aspects of embolotherapy was gained by repeated performances using this model. Simplicity of creation, clear angiographic visibility of feeders, a nidus and a draining vein, and hemodynamic similarities with cerebral arteriovenous malformations make this an attractive in vivo experimental model for learning the principles of embolotherapy, testing new embolic agents, and training/gaining experience in embolization techniques.

Animals↗
PubMed1995

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.

Adult↗
PubMed1995

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.

Adult↗
PubMed1995

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.

Adolescent↗
PubMed1994

Experimental saccular aneurysms. I. Review of surgically-constructed models and their laboratory applications.

Experimental models of intracranial saccular aneurysms are a useful contribution to our basic understanding of these lesions. Currently, the commonest in use are those constructed surgically in laboratory animals. We review the numerous surgical techniques available since the 1950s, and the research applications and uses of experimental aneurysms. Further development and use of such models is greatly encouraged in future pathophysiological, hemodynamic, and therapeutic investigations of intracranial saccular aneurysms.

Animals↗
PubMed1994

Saccular aneurysms in moyamoya disease: endovascular treatment using electrically detachable coils.

Moyamoya disease (MMD) often presents with subarachnoid hemorrhage due to rupture of saccular aneurysms. We describe three patients with cerebrovascular features of MMD in whom four aneurysms of the posterior circulation were endovascularly occluded by electrothrombosis using the recently developed Guglielmi electrically detachable coils (GDC). Near total occlusion was achieved in three aneurysms. Subtotal occlusion was achieved in one aneurysm. This patient developed complications related to the neuroleptic anesthesia administered for the procedure. The particular hazards of anesthesia and aneurysmal surgery in MMD are discussed, and comparison is made with the benefits of using the GDC. Initial experience suggests that this endovascular approach is safe and effective in the treatment of saccular aneurysms in MMD. However, follow-up is necessary to assess long-term persistence of aneurysm obliteration.

Adult↗
PubMed1994

Potential toxic effects of superselective injection of amobarbital sodium on microvasculature: a study in an animal model.

PURPOSE: To determine whether microvascular damage occurs from superselective intraarterial injection of amobarbital sodium using the swine endovascular embolization model. METHODS: Thirty-four swine underwent percutaneous femoral puncture for superselective catheterization of the proximal artery of the rete. Varying concentrations of amobarbital sodium were prepared (12.5 to 100 mg/mL solution) in either normal saline or sterile water (105 mOsm/L to 1138 mOsm/L) of which one concentration was infused slowly into one ipsilateral rete. Control infusions were also performed. Histopathologic changes were evaluated at 30 minutes and 10 days after infusion, using standard light and electron microscopy techniques. RESULTS: Moderate vasospasm occurred only in three swine at 100 mg/mL amobarbital sodium in normal saline. Light microscopy showed no significant histologic changes in the retia at any of the tested concentrations of amobarbital sodium. Electron microscopy showed ultrastructural alterations in the intima only at the higher amobarbital sodium concentrations. CONCLUSIONS: Concerns for inducing significant damage to cerebral microvasculature by superselective injection of amobarbital sodium at the usually recommended concentrations and doses are probably not justified.

Amobarbital↗
PubMed1994

An experimental arteriovenous malformation model in swine: anatomic basis and construction technique.

We assessed the feasibility of creating an experimental arteriovenous malformation model in swine by diverting and increasing blood flow through bilateral retia mirabilia. This was achieved by surgical formation of a large right-sided carotid-jugular fistula, in combination with endovascular occlusion of several neck arteries ipsilateral to the fistula. Using this technique, 11 of 13 swine demonstrated an acute-phase angiographic simulation of an arteriovenous malformation. There was rapid circulatory diversion from the left ascending pharyngeal artery ("feeder"), across both retia ("nidus"), and fast retrograde flow into the right ascending pharyngeal and common carotid arteries ("draining vein") toward the fistula. The relevant vascular anatomy of the swine head and neck is outlined, and steps in the construction of this arteriovenous malformation model are detailed.

Anastomosis, Surgical↗
PubMed1994

Endovascular occlusion of intracranial aneurysms with electrically detachable coils: correlation of aneurysm neck size and treatment results.

PURPOSE: To devise a method to measure aneurysm neck size on angiographic films, and to correlate the sizes obtained with the extent of endovascular aneurysm occlusion, performed with electrically detachable coils. METHODS: The angiograms of 79 intracranial aneurysms treated by endovascular occlusion using electrically detachable coils were retrospectively analyzed. A method using the average reported caliber of the major intracranial vessels was applied to determine the aneurysm neck sizes on the diagnostic angiograms. The cases were divided into two groups according to neck size, 4 mm being the discriminative value for small and wide necks. The posttreatment angiogram of each case was analyzed to evaluate the degree of occlusion achieved by the technique. RESULTS: Necks were successfully measured in 95% of the aneurysms. Complete aneurysm thrombosis was observed in 85% of the small-necked aneurysms and in 15% of the wide-necked aneurysms. CONCLUSIONS: Accurate angiographic measurements of neck diameter can be obtained in most aneurysms. The size of an aneurysm neck correlates well with the results of the endovascular treatment. Small-necked aneurysms can be satisfactorily occluded with this technique. In wide-necked aneurysms this technique should be reserved for lesions having a high surgical risk.

Aneurysm, Ruptured↗
PubMed1994

An in vivo arteriovenous malformation model in swine: preliminary feasibility and natural history study.

PURPOSE: To assess the feasibility, natural history, and preliminary physiologic validation of creating an in vivo arteriovenous malformation model in swine. METHODS: A transorbital puncture technique into the cavernous sinus was used to create an arteriovenous communication between the rostral rete and the cavernous sinus in eight swine. Short-term patency and hemodynamic behavior were assessed clinically and by serial angiography. Acute phase physiologic characterization of four models was also performed, using intravascular pressure and Doppler blood flow velocity measurements. RESULTS: Large arteriovenous shunts between the rostral rete and cavernous sinus were consistently produced, which mimicked the angiographic features of cerebral arteriovenous malformations in humans. Classic changes in intraarterial and intravenous pressures and blood flow velocities were also observed. Early pathophysiologic evolution occurred in two animals, consisting of recruitment of previously unseen collateral vessels. Spontaneous occlusion of the arteriovenous shunt occurred in most animals within 7 days because of a rigorous fibroblastic response. CONCLUSIONS: A simple technique for creating an arteriovenous malformation model in swine is now possible and is promising for future studies.

Animals↗
PubMed1994

Use of a Doppler guide wire for intravascular blood flow measurements: a validation study for potential neurologic endovascular applications.

PURPOSE: To conduct a validation study of a Doppler guide wire for potential neuroendovascular applications. METHODS: A 12-MHz, 0.018-inch Doppler guide wire was evaluated in eight swine under various blood flow conditions using two types of in vivo cerebrovascular models (physiologic and arteriovenous shunting). Flow conditions were mechanically and pharmacologically altered. Doppler average peak velocity was compared with volumetric blood flow, and flow profile corrections were calculated and analyzed. Qualitative aspects of the Doppler guide wire spectra were also assessed. RESULTS: Plots of average peak velocity versus volumetric blood flow showed excellent linear relationships (r2 > 0.94), which were maintained at high flow conditions (average peak velocity, 99 to 236 cm/sec; volumetric blood flow, 392 to 889 mL/min). Values of flow profile correction varied from 0.43 to 0.94 and showed no consistent relationship to changes in volumetric blood flow. CONCLUSIONS: The excellent correlation between average peak velocity and volumetric blood flow over a wide range of blood flow conditions and the additional qualitative information of the Doppler guide wire spectra establish a foundation for clinical implementation. The unpredictable variations of flow profile corrections remain obstacles for calculating volumetric blood flow based on Doppler guide wire average peak velocity.

Animals↗