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Biomedical subjects

F G Diaz

Publications and source records attributed to F G Diaz.

At least 127 records · Page 7Linked to original sources
PubMed1984

Corrosion of aneurysm clips: evaluation and clinical implications. Part II: Individual performance.

The intracranial fracture of aneurysm clips due to stress corrosion failure is an increasingly common long term postoperative complication. To study the susceptibility of different clips to this process, we evaluated seven aneurysm clips (Mayfield, Yasargil, Vari-Angle McFadden, Scoville, Heifetz, and Pivot) in vitro. Microstructures, hardness, chemical composition, and susceptibility to stress corrosion failure were all measured by standard metallurgical techniques. Certain clips such as Heifetz, Pivot, and Vari-Angle showed a much greater propensity to stress corrosion failure than the others. As a result of our tests, we recommend that only the clips that show high stress corrosion resistance in in vitro testing should be considered for long term in vivo implantation.

Corrosion↗
PubMed1984

Intracranial clips: an examination of the devices used for aneurysm surgery.

A properly functioning aneurysm clip is of paramount importance in the surgical ablation of intracranial aneurysms. An appropriate match between the closing force needed to ablate an aneurysm and the force exerted by the aneurysm clip must be achieved. In this study, the opening and closing forces exerted by several commonly used aneurysm clips were tested. There was a strong correlation between the classification of the clips, according to the Dujovny system, and their mechanical behavior. Minimal variability among different lots of the same clip type and minimal hysteresis were generally exhibited by the alpha mobile fulcrum class clips, such as the Yasargil, Vari-Angle McFadden, Scoville, and Mayfield clips. Significant exceptions included several types of Mayfield and Drake clips. In contrast, pivot class clips generally showed twice as much lot variability among different lots, as well as a significant amount of hysteresis. Clips of this class include the Vari-Angle, Heifetz, and Pivot clips. Because significant variations in clip force exist and because several other factors can compound these differences, it is suggested that aneurysm clips be individually tested for their closing forces before they are used in an operation.

Humans↗
PubMed1984

Microsurgical anatomy of the recurrent artery of Heubner.

The recurrent arteries of Heubner were studied in 30 unfixed human brains (60 hemispheres) obtained from routine autopsies of individuals with a mean age of 34 years. The arteries were injected with tinted polyester resin via cannulation of the internal carotid arteries, and dissected under microscopic magnification. The recurrent artery of Heubner was absent in two hemispheres and double in seven hemispheres, either with a separate origin (in two) or from a common stem (in five). The artery of Heubner had a mean outer diameter of 0.8 +/- 0.04 mm (range 0.3 to 1.5 mm) and a mean length of 23.4 +/- 1.1 mm (range 12 to 38 mm). It originated from the A2 segment of the anterior cerebral artery (ACA) in 57% of the specimens, from the junction of the ACA and the anterior communicating artery in 35%, and from the A1 segment of the ACA in 8%. Three types of recurrent courses were observed. In the Type I or superior course, seen in 41 (63%) of the 65 arteries, the artery followed the superior wall of the A1 segment of the ACA. In the Type II or anterior course, the arteries found in 22 (34%) of specimens maintained a rostral position in relation to the A1 segment. In the Type III or posterior course, taken by two (3%) arteries, a posterior course of the vessel in the anterior perforated substance was found. The branching pattern was identified down to a range of 100 to 200 mu, and the average number of branches was 6.5 +/- 0.4 (range 3 to 12). Four groups of branches were observed. The olfactory group was represented in 91% by a single olfactory branch, with a mean outer diameter of 0.3 +/- 0.03 mm. On average, 1.9 +/- 0.27 frontal branches were found with a mean diameter of 0.13 +/- 0.01 mm. The branches penetrating the anterior perforated substance had a larger outer diameter (mean 0.4 +/- 0.03 mm) with an average number of 2.5 +/- 0.2 branches. The Sylvian fissure branches were more numerous (mean 3 +/- 0.3) with a mean outer diameter of 0.4 +/- 0.03 mm. The point of penetration of the main trunk was found to be constant at the level of the lateral perforated substance-medial Sylvian fissure in 85% of the cases. This report emphasizes the advantages of the intravascular casting resin injection technique in unfixed human brains over other conventional methods. It also describes the application of these anatomic data to the surgical strategy for the anterior circle of Willis, including the possible use of the recurrent artery of Heubner for microvascular reconstructive procedures.

Adult↗
PubMed1984

Microsurgical anatomy of the proximal segments of the middle cerebral artery.

The microvascular anatomy of the proximal segments (M1 and M2) of the middle cerebral artery (MCA) was studied in 70 unfixed brain hemispheres from 35 cadavers. The arteries were injected with a tinted polyester resin and dissected under magnification by microsurgical techniques. The authors studied the outer diameter (OD), length, site of origin, and pattern of branching of the main trunk, secondary trunks, and the initial insular portion of the cortical branches of the MCA. The degree of mobilization of the arteries lying over the insular cortex was also assessed. The main trunk of the MCA, which had an OD of 3 +/- 0.1 mm bilaterally and a length of 15 +/- 1.1 mm in the right hemisphere and 15.7 +/- 1.3 mm in the left hemisphere, could be divided into four groups: Group I: absence of a main division (that is, a single-trunk type of MCA) (in 6% of cases); Group II: bifurcation (64%); Group III: trifurcation (29%); and Group IV: quadrifurcation (1%). The secondary trunks resulting from the division of the main trunk of the MCA had a mean OD ranging from 1.4 to 2.3 mm and a mean length that varied from 12.1 to 14.9 mm. The mean OD of the cortical branches measured near their origin in the main and secondary trunks indicated that the angular artery was the largest vessel, with a mean OD of 1.5 mm on both sides of the brain. The temporopolar artery was the smallest, with a mean OD of 0.8 mm in the right hemisphere and 0.9 mm in the left hemisphere. The authors also describe the patterns of origin of the cortical vessels from the main trunk (early branches) and from the secondary trunks, as well as their branching pattern at the site of origin (single vessels and common stems). These anatomical data indicate that it is possible to perform microvascular reconstructive procedures, such as anastomosis, grafting, and reimplantation of branches in the insular area. The advantages of using unfixed specimens, intravascular injections, and magnification to reproduce in vivo conditions as closely as possible are also discussed.

Cerebral Arteries↗
PubMed1984

Surgical reconstruction of the proximal vertebral artery.

The authors have reviewed their experience in the management of 55 patients admitted to Henry Ford Hospital with symptoms of vertebrobasilar insufficiency and associated proximal vertebral artery stenosis or occlusion. In 48 patients, the symptoms occurred as multiple repeated events, five of which resulted in permanent deficits. The remaining seven patients had single events, four of which caused permanent deficit. These patients had been treated unsuccessfully with antiplatelet agents (37 cases) and with anticoagulant drugs (15 cases) before surgery. Most patients had multiple angiographic abnormalities, including bilateral vertebral stenosis in 19 cases, unilateral vertebral stenosis and contralateral occlusion in 18, unilateral vertebral hypoplasia and contralateral stenosis in 10, subclavian artery stenosis with steal in seven, and bilateral vertebral artery occlusion in one case. Posterior communicating arteries could not be demonstrated angiographically in 18 patients. Thirty-four patients had associated stenotic or occlusive lesions of the internal carotid artery. Forty-eight underwent a vertebral-to-carotid artery transposition. Of these, 18 had an associated carotid endarterectomy and seven had a vertebral artery endarterectomy immediately before the transposition. Two patients had saphenous vein grafts, one from the subclavian and one from the common carotid artery to the vertebral artery. Other surgical procedures included vertebral artery ligation in one case, transposition of the vertebral artery to the thyrocervical trunk in two cases and to the subclavian artery in one case, and endarterectomy of the origin of the vertebral artery in one case. All but two patients had complete resolution of their symptoms: one had persistent dizziness and the other had syncopal episodes. Complications included transient Horner's syndrome (30 cases) which became permanent in four cases, vocal cord paralysis (three cases), elevated hemidiaphragm without respiratory difficulty (two cases), and superficial would infection (one case). There were no deaths. Although the presentation of patients with vertebrobasilar insufficiency is generally characteristic, we believe that a specific diagnosis can be established only by angiographic means. Anticoagulants have been used to alleviate symptoms in some cases but are ineffective in solving the primary hemodynamic problem. Surgical reconstruction of the affected area deserves further evaluation in the management of these patients.

Adult↗
PubMed1983

Mechanical and metallurgical properties of vascular clips designed for temporary use.

Six commonly used surgical clips (Kleinert-Kutz, Pivot, Vari-Angle, Yasargil, Biemer, and Acland) that have been designated by their manufacturer as being suitable for temporary occlusion were studied in terms of their mechanical and metallurgical properties. Opening and closing forces were determined for all of the clips. Significant variations in clip force with respect to blade gap were found in all of the pivot-type clips. Metallurgical testing showed that all six clips exhibited properties that contraindicate long-term implantation.

Corrosion↗
PubMed1983

The surgical management of vertebrobasilar insufficiency.

Vertebrobasilar insufficiency may result from structural lesions anywhere along the vertebrobasilar system. Recently developed techniques in angiography and microsurgery have made the vertebrobasilar system more accessible to surgical therapy. The syndrome of vertebrobasilar insufficiency is discussed, and our experience with the surgical treatment of lesions from the vertebral origin to the distal basilar region is reviewed.

Anticoagulants↗
PubMed1983

Combined reconstruction of the vertebral and carotid artery in one single procedure.

Patients suffering from vertebrobasilar insufficiency frequently have multiple areas of involvement in the extracranial circulation. Eight patients admitted to Henry Ford Hospital had symptoms suggestive of vertebrobasilar insufficiency and angiograms showing multiple abnormalities. A combined operation that reconstructed the carotid and vertebral circulations in one single procedure was completed in all patients with minimal morbidity and no mortality. The surgical procedure is described in detail.

Aged↗
PubMed1982

Endarterectomy of the vertebral artery from C2 to posterior inferior cerebellar artery intracranially.

A new technical approach to endarterectomy of the vertebral artery at the cranial cervical junction is discussed. A patient had symptoms of vertebrobasilar insufficiency on clinical examination. Angiography demonstrated a stenotic plaque in the vertebral artery at the level of C1, and an additional tandem lesion at the origin of the posterior inferior cerebellar artery. He underwent vertebral endarterectomy and was symptomatically improved postoperatively. The surgical approach used and possible alternatives will be discussed in detail.

Cerebellum↗
PubMed1982

Preoperative neurobehavioral impairment in cerebral revascularization candidates.

We examined level of performance in 40 candidates for cerebral revascularization and found substantial variability on general indices of neuropsychological performance. Patients differed by duration of their longest ischemic attack, by surgery type, but not by time since onset of their first ischemic attack. Duration of the longest ischemic attack correlated highly with neuropsychological summary scores. In contrast, symptom duration was unrelated to level of performance in 18 additional patients with histories consistent with cerebrovascular ischemia who did not undergo surgery subsequently. We concluded that initial status on neuropsychological tests is an important variable to consider in postoperative followup of patients undergoing cerebral revascularization. More detailed clinical history and finer grained analysis of neuropsychological data promised to reveal additional relationships among clinical symptoms, neurobehavioral data, and underlying neuropathology.

Brain Ischemia↗
PubMed1982

Pharmacologic management of subarachnoid hemorrhage.

Subarachnoid hemorrhage, following rupture of an intracranial aneurysm, affects about 25 000 people in the U.S. each year. Less than half the patients who survive until hospital admission have an overall favorable outcome. This high morbidity and mortality rate is a result of serious complications following the initial subarachnoid hemorrhage, the most significant of these being rebleeding and cerebral ischemia secondary to vasospasm. While surgical clipping of the aneurysm is the most definitive therapy, this procedure may be postponed for a week or two after the initial hemorrhage, depending on the patient's clinical condition. Pharmacological therapy is a critical part of the preoperative care of these patients and of the postoperative management of complications. This article discusses the syndromes of rebleeding and vasospasm and reviews the current pharmacologic therapy for each.

Adrenergic beta-Agonists↗
PubMed1982

Ischemic complications after combined internal carotid artery occlusion and extracranial-intracranial anastomosis.

Seven of 120 aneurysm patients admitted to the Henry Ford Hospital from October 1978 to August 1981 had giant internal carotid artery aneurysms that were treated by a combined internal carotid artery occlusion and extracranial-intracranial anastomosis. Three of these patients developed postoperative ischemic complications during the progressive closure of the carotid artery. These complications included the transient onset of syncope, hemiparesis, hemisensory deficits, and dysphasia. These complications resolved after the clamp was reopened and/or intravenous heparin was given. The possible mechanisms involved in the development of ischemia included the development of emboli at the occlusion site or inadequate flow originating from the area of the anastomosis. Prolonged occlusion of the vessel over a 7- to 10-day course with concurrent administration of intravenous heparin is recommended.

Adult↗
PubMed1982

Posterior circulation revascularization. Superficial temporal artery to superior cerebellar artery anastomosis.

Eight patients were evaluated for severe vertebrobasilar insufficiency (VBI). There were five males and three females, with an average age of 60.2 years (range 42 to 67 years). Three were diabetic and five hypertensive, including two patients who had both diseases. Seven of the eight had ongoing episodes of VBI refractory to anticoagulant and/or antiplatelet agents. Symptoms included two or more of the following in all patients: dizziness, diplopia, hemiparesis, hemihypesthesia, perioral numbness, bilateral visual blurring, dysarthria, and ataxia. Angiography revealed severe atherosclerotic stenosis of the proximal or midsection of the basilar artery in all patients. A 10-cm segment of the anterior or posterior division of the superficial temporal artery (STA) was anastomosed to a proximal segment of the superior cerebellar artery (SCA) through a right subtemporal approach. Seven of eight (87%) postoperative angiograms demonstrated patency as evidenced by filling of the SCA and, in most cases, of the basilar artery. Six of the eight patients were improved or asymptomatic after the operation, one was unchanged, and one died. The average follow-up period was 14 months, with a range of 4 to 23 months. Transient morbidity included temporal lobe swelling in four patients and a subdural hematoma in one. Anastomosis of the STA to the SCA is a feasible therapeutic option in the patient with VBI secondary to stenosis of the proximal or midsection of the basilar artery.

Adult↗