PubMed Health⌕ Search

Biomedical subjects

F Viñuela

Publications and source records attributed to F Viñuela.

At least 91 records · Page 5Linked to original sources
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↗
PubMed1993

Pathologic findings in a patient with a vein of Galen aneurysm treated by staged endovascular embolization.

Vein of Galen aneurysms are uncommon malformations that can be treated with a combination of endovascular embolization and surgery. Since the relevant techniques are new and innovative, their pathologic sequelae are not yet well described. A patient treated with staged embolization over a 15-month period developed evidence of cerebral venous hypertension on angiography. At necropsy, we observed marked myointimal proliferation of the aneurysm wall, dura, and cerebral vessels in addition to severe widespread encephalomalacia, calcinosis, and rare mural thrombi. These vascular changes have not been previously described in cases of vein of Galen aneurysm, and may, in part, be a consequence of embolization therapy.

Cerebral Veins↗
PubMed1993

The pathology of arteriovenous malformations of the brain treated by embolotherapy. II. Results of embolization with multiple agents.

Light microscopic and immunohistochemical examination was undertaken of intracranial arteriovenous malformations (AVMs) surgically resected from 18 patients, each of whom had undergone preoperative angiographic embolization with multiple agents. Distinct patterns of tissue reaction to these agents were noted, even when more than one substance was present in a vascular lumen. Avitene produced the mildest tissue response but resulted in relatively early endothelialization and recanalization. Cyanoacrylates were longer-lasting but associated with more acute and chronic (including granulomatous) inflammation and vessel wall changes. Polyvinyl alcohol foam/ethanol mixture had intermediate properties. Endothelial proliferation over embolization material was confirmed using immunohistochemical application of an antibody to cell proliferation-specific proteins. The significance of these findings for combined endovascular and surgical treatment of cerebral vascular malformations is discussed.

Adolescent↗
PubMed1993

Pediatric intracranial vascular malformations: evaluation of treatment results with color Doppler US. Work in progress.

To determine the value of color Doppler ultrasound (US) in the preoperative assessment and evaluation of treatment results in children with intracranial vascular malformations (VMs), the authors performed 36 color Doppler US studies in nine children who underwent endovascular embolization. Color flow imaging with spectral waveform analysis of feeding arteries, nidus, draining veins, and uninvolved cranial vasculature was performed, and correlation was made with other imaging findings. In most VMs, color Doppler US enabled the authors to map the lesion completely. Hemodynamic changes after embolization included improvement in blood supply to uninvolved portions of the brain and increase in caliber and flow of feeding vessels that were not occluded during embolization. Serial volume flow measurements were performed with Doppler US in major extracranial arteries. Success of embolization was indicated by substantial decrease of total carotid artery flow. Color Doppler US is a noninvasive modality that adds important imaging and hemodynamic data to those provided by angiography.

Cerebral Angiography↗
PubMed1993

Therapeutic alternatives for vein of Galen vascular malformations.

From September, 1986, to March, 1990, the authors treated 28 children harboring a vein of Galen vascular malformation. Eleven (39.3%) of the patients were neonates, 13 (46.4%) were 1 to 2 years old, and four (14.3%) were more than 2 years old. Fifteen patients (53.6%) presented with severe congestive heart failure, six (21.4%) had seizures, four (14.3%) had hydrocephalus, and three (10.7%) presented with intraventricular hemorrhage. Based on the Yaşargil classification of malformations, 10 lesions (35.7%) were Type I, seven (25%) were Type II, eight (28.6%) were Type III, and three (10.7%) were Type IV. In 11 patients (39.3%), a combined transfemoral, transarterial, and transvenous embolization of the vein of Galen malformation was performed. A pure transtorcular approach was utilized in eight patients (28.6%), and postembolization surgical clipping of arterial feeders was performed in two cases with intractable congestive heart failure. Complete anatomical occlusion of the galenic malformation was achieved in 13 patients (46.4%). An immediate postembolization improvement in the patient's clinical status was obtained in 23 (82.1%) of 28 patients and a good long-term clinical outcome was seen in 17 patients (60.7%). Five deaths (17.9%) occurred in this series of 28 patients; three (10.7%) were related to a transtorcular embolization and two (7.1%) to the unchanged natural history of the disease.

Cerebral Veins↗
PubMed1993

Magnetoencephalographic localization of a language processing cortical area adjacent to a cerebral arteriovenous malformation. Case report.

In order to accurately estimate the risk of surgery for dominant perisylvian arteriovenous malformations, the topographical relationship of the lesion to language cortex must be determined. A case is presented in which a magnetoencephalographic (MEG) study was used to map preoperatively and noninvasively an intracortical source of speech-receptive cortex in a 25-year-old right-handed man with a dominant left temporal lobe arteriovenous malformation. The speech-evoked magnetic field was analyzed at 36 positions over the left hemisphere in response to presentations of the consonant-vowel syllables "da" and "ga." A topographical map of the magnetic component evoked at 110 msec after stimulus onset, which was negative going to the vertex in concurrent electrical recordings, was congruent with a superficial cortical neuronal current source. This source was displaced from that usually observed in normal individuals to tonal or click stimuli, being superior to the probable location of auditory cortex, and superior and anterior to the probable location of Wernicke's area as conventionally described. The MEG results were in accord with the determination of position of a language-processing cortical area as assessed by direct electrical stimulation of the cortex during surgery under local anesthesia, and by superselective Amytal (amobarbital) injection during angiography. The MEG recordings and exposed brain stimulation sites were coordinated by cranial measurements, skull x-ray landmarks, and angiographic anatomy. Investigations such as this, which compare MEG findings with those from established clinical procedures, are an essential step in determining the physiological and anatomical utility of magnetoencephalography for noninvasive clinical functional localization.

Adult↗
PubMed1993

True anatomical compartmentalization of the cavernous sinus in a patient with bilateral cavernous dural arteriovenous fistulae. Case report.

An unusual case of complete anatomical compartmentalization of the cavernous sinus in a patient with bilateral Type D cavernous dural arteriovenous fistulae is described. This anatomical anomaly isolated the anterior cavernous sinus and orbital venous system, which was primarily responsible for the patient's clinical presentation. The compartmentalization of the cavernous sinus also limited options for definitive endovascular therapy to a transvenous approach via the superior ophthalmic vein.

Adult↗
PubMed1992

Fluid equations applied to blood flow measurement using digital videodensitometry.

RATIONALE AND OBJECTIVES: Time-dependent fluid flow is computed from projection radiographs without bolus tracking by applying the fluid equations of continuity and incompressibility. METHODS: The fluid equations are combined and integrated to yield an equation that describes instantaneous mass conservation within a vessel segment. The technique is demonstrated using phantom images and patient data obtained using a digital subtraction angiography (DSA) system. RESULTS: Instantaneous and mean flow rates are successfully computed with this algorithm, but the uncertainties are overestimated. In a 1.0-cm diameter tube, instantaneous and mean velocities corresponding to 7.3 cm per frame are computed within 13% uncertainty using a 4.0-cm segment length. Mean flow rates computed from standard diagnostic angiograms taken from three different projections agree within 16%. CONCLUSIONS: This technique can successfully compute time-dependent flow rates from DSA image sequences with large fluid displacements between frames. The accuracy is strongly dependent on the magnitude of the contrast density gradient.

Algorithms↗
PubMed1992

Carotid-cavernous fistula caused by a ruptured intracavernous aneurysm: endovascular treatment by electrothrombosis with detachable coils.

A case of carotid-cavernous fistula caused by a ruptured intracavernous aneurysm is reported. The fistula was treated with electrothrombosis by the detachment of two platinum coils into the aneurysm via an endovascular transvenous approach; the fistula was closed, and the patient has recovered completely. The advantages of using electrodetachable platinum coils include thrombogenicity, controllable deposit, radiopacity, and biocompatibility.

Adult↗
PubMed1992

Endovascular treatment of posterior circulation aneurysms by electrothrombosis using electrically detachable coils.

In a multicenter study, 120 patients with intracranial aneurysms presenting a high surgical risk were treated using electrolytically detachable coils and electrothrombosis via an endovascular approach. The results of treatment in patients with posterior fossa aneurysms (42 patients with 43 aneurysms) are presented. The most frequent clinical presentation was subarachnoid hemorrhage (24 cases). The clinical follow-up periods ranged from 1 week to 18 months. Complete aneurysm occlusion was obtained in 13 of 16 aneurysms with a small neck and in four of 26 wide-necked aneurysms. A 70% to 98% thrombosis of the aneurysm was achieved in 22 of 26 aneurysms with a wide neck and in three of 16 small-necked aneurysms. One aneurysm could not be treated due to a technical complication. Two cases required postprocedural surgical clipping of a residual aneurysm. One patient (originally in Hunt and Hess Grade V) experienced procedural rupture of the aneurysm requiring an emergency parent artery occlusion. He eventually died 5 days later. Another patient (originally in Grade IV) had coil migration and posterior cerebral artery territory ischemia. A third patient developed a permanent neurological deficit (hemianopsia) after complete occlusion of a wide-necked basilar bifurcation aneurysm. One patient, harboring an inoperable giant basilar bifurcation aneurysm, died from aneurysm bleeding 18 months after partial occlusion. Overall morbidity and mortality rates related to treatment were 4.8% (two cases) and 2.4% (one case), respectively (2.6% and 0% if considering only patients in Hunt and Hess Grades I, II, and III). It is suggested that this technique is a viable alternative in the management of patients with posterior fossa aneurysms associated with high surgical risk. Longer angiographic and clinical follow-up study is necessary to determine the long-term efficacy of this recently developed endovascular occlusion technique. Close postoperative angiographic and clinical monitoring of patients with wide-necked subtotally occluded aneurysms is mandatory to check for potential aneurysmal recanalization, regrowth, and rupture.

Adolescent↗
PubMed1991

Electrothrombosis of saccular aneurysms via endovascular approach. Part 1: Electrochemical basis, technique, and experimental results.

Eleven experimental saccular aneurysms were created on the common carotid artery of swine. Between 3 and 15 days after creation of these aneurysms, they were thrombosed via an endovascular approach, using a very soft detachable platinum coil delivered through a microcatheter positioned within the aneurysm. This detachable platinum coil was soldered to a stainless steel delivery guidewire. Intra-aneurysmal thrombosis was then initiated by applying a low positive direct electric current to the delivery guidewire. Thrombosis occurred because of the attraction of negatively charged white blood cells, red blood cells, platelets, and fibrinogen to the positively charged platinum coil positioned within the aneurysm. The passage of electric current detached the platinum coil within the clotted aneurysm in 4 to 12 minutes. This detachment was elicited by electrolysis of the stainless steel wire nearest to the thrombus-covered platinum coil. Control angiograms obtained 2 to 6 months postembolization confirmed permanent aneurysm occlusion as well as patency of the parent artery in all cases. No angiographic manifestation of untoward distal embolization was noted. Due to the encouraging results of this research, this technique has been applied in selected clinical cases which are described in Part 2 of this study.

Aneurysm↗
PubMed1991

Electrothrombosis of saccular aneurysms via endovascular approach. Part 2: Preliminary clinical experience.

Fifteen patients with high-risk intracranial saccular aneurysms were treated using electrolytically detachable coils introduced via an endovascular approach. The patients ranged in age from 21 to 69 years. The most frequent clinical presentation was subarachnoid hemorrhage (eight cases). Considerable thrombosis of the aneurysm (70% to 100%) was achieved in all 15 patients, and preservation of the parent artery was obtained in 14. Although temporary neurological deterioration due to the technique was recorded in one patient, no permanent neurological deficit was observed in this series and there were no deaths. It is believed that this new technology is a viable alternative in the management of patients with high-risk intracranial saccular aneurysms. It may also play an important role in the occlusion of aneurysms in the acute phase of subarachnoid hemorrhage.

Adult↗
PubMed1991

Combined endovascular embolization and surgery in the management of cerebral arteriovenous malformations: experience with 101 cases.

The authors describe their experience with 101 cerebral arteriovenous malformations (AVM's) treated by endovascular embolization followed by surgical removal. Fifty-three patients presented with intracranial hemorrhage and 35 had seizures. Based on the classification of Spetzler and Martin, two AVM's were Grade I, 13 were Grade II, 26 were Grade III, 43 were Grade IV, and 17 were Grade V. Fifty-six AVM's were in the right hemisphere, 28 were in the left hemisphere, 12 were in the corpus callosum, and five involved the cerebellum. In 50 cases, presurgical obliteration of 50% to 75% of the AVM nidus was achieved by embolization, and in 31 cases this percentage increased to between 75% and 90%. In 97 (96%) patients, complete surgical removal of the AVM was obtained. Morbidity resulting from preoperative endovascular embolization was classified as mild in 3.9% of the cases, moderate in 6.9%, and severe in 1.98%. The death rate related to embolization was 0.9%. The immediate postsurgical morbidity was classified as mild in 5.9% of the cases, moderate in 10.8%, and severe in 5.9%. The overall long-term morbidity was mild in 5.9% of the cases, moderate in 6.9%, and severe in 1.98%. Two patients (1.98%) died due to intractable intraoperative hemorrhage and two (1.98%) as a result of postsurgical pulmonary complications.

Adolescent↗
PubMed1990

Pre-operative micro-angioplasty of refractory vasospasm secondary to subarachnoid hemorrhage.

A patient with subarachnoid hemorrhage secondary to a basilar artery aneurysm developed severe bilateral middle and anterior cerebral artery vasospasm with extensive neurologic deficits. Microangioplasty of the middle cerebral artery segments bilaterally led to reversal of the neurologic deficits, allowing early operative treatment of the aneurysm in a previously inoperable patient.

Aged↗
PubMed1990

Use of a new mixture for embolization of intracranial vascular malformations. Preliminary experimental experience.

The internal carotid artery system in swine has a special anatomic configuration similar to a brain "arterial-arterial malformation." The internal carotid artery breaks up into a multitude of fine channels (rete mirabile) situated at the base of the skull on the side of the hypophysis. This anatomic arterial model was used to analyze acute and chronic angiographic and histological changes after occlusion of the rete mirabile with I) avitene, II) avitene, and 50% ethanol, III) avitene, 30% ethanol and Polyvinyl alcohol, IV) avitene 50% ethanol and Polyvinyl alcohol, V) IBCA and VI) silk. Histopathological changes observed in the rete mirabile six weeks following occlusion demonstrated that a mixture of avitene, 30% ethanol and Polyvinyl alcohol and IBCA produced the best anatomic results. Embolization with avitene, PVA and ethanol induced a more bland histological reaction than the one observed with IBCA. Preliminary clinical experience with this mixture is reassuring in those cases in which the AVM was surgically resected. The partially thrombosed AVM was easily depressed and compressed by the neurosurgeon allowing for satisfactory hemostasis in and around the nidus of the AVM.

Animals↗