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PubMed1987

Effects of verapamil and converting enzyme inhibition on bilateral renal function of two-kidney, one-clip hypertensive rats.

Experiments were conducted in two-kidney, one-clip renal vascular hypertensive rats (GHR) to assess the responses of each kidney to acute treatment with the antihypertensive calcium channel blocking agent verapamil in the presence and in the absence of converting enzyme inhibitor (CEI). One group of GHR (0.2 mm inner diam. clip 3 weeks before study) were examined during a control period, and during a second period of infusion of verapamil (600 micrograms h-1 kg-1). A second group of GHR were examined during a control period, during CEI (teprotide, 3 mg h-1 kg-1) infusion and during a third period of verapamil (600 micrograms h-1 kg-1) infusion superimposed on CEI infusion. Although systemic blood pressure (BP) decreased from 175 +/- 4 to 149 +/- 5 mmHg (mean +/- SEM) in response to verapamil alone, renal blood flow for non-clipped kidneys increased from 5.9 +/- 0.4 to 6.5 +/- 0.3 ml/min, indicating a 30% reduction of renal vascular resistance (P values less than or equal to 0.01; n = 9). Glomerular filtration rate (GFR) for non-clipped kidneys (n = 24) increased from 0.91 +/- 0.09 to 1.47 +/- 0.14 ml/min and filtration fraction increased from 0.32 +/- 0.04 to 0.47 +/- 0.03 (P values less than or equal to 0.05). Urine flow rate and absolute and fractional sodium excretion for non-clipped kidneys increased. GFR for clipped kidneys decreased during verapamil. Treatment with CEI alone resulted in nearly identical responses of BP and function of the non-clipped kidney, except filtration fraction was unchanged. The addition of verapamil to ongoing converting enzyme blockade tended to augment the increased GFR of the non-clipped kidney. Plasma renin activity (PRA) increased from 30 +/- 3 to 59 +/- 7 ng of angiotensin (ANG) I h-1 ml-1 with verapamil alone, a significantly larger increment than the increase of PRA from 27 +/- 5 to 39 +/- 9 ng of ANG I h-1 ml-1 in GHR subjected to comparable blood pressure reduction by mechanical aortic constriction. Verapamil resulted in many similar effects on renal function to those observed during blockade of converting enzyme. The increased filtration fraction observed in response to verapamil may be the result of vasodilatation of the afferent arteriole or of an increase in the glomerular ultrafiltration coefficient.

Angiotensin II↗

PubMed2001

Preservation of endothelial integrity and function in experimental vascular anastomosis with non-penetrating clips.

BACKGROUND: Vascular repair with sutures is associated with disruption of the endothelial lining and subsequent thrombus formation on the intraluminal lesions. This experimental study was designed to determine whether the use of non-penetrating clips improved endothelial preservation. METHODS: In ten female pigs, 25-mm arteriotomies were made in both carotid arteries. The arteriotomies were repaired with jugular vein patches. On the left side, the repair was done with 1.4-mm titanium clips, and on the right side with two running 6/0 polypropylene sutures. Next, the aorta was divided and subsequently repaired with 2-mm clips in five of these pigs, and with two running 5/0 polypropylene sutures in the remaining five pigs. Endothelial function was studied at the anastomotic site in the carotid arteries by determination of endothelium-dependent and -independent relaxatory responses. Morphometric examination of the carotid arteries and inspection of the aortic endothelium were performed by means of scanning electron microscopy. RESULTS: Maximal endothelium-dependent relaxation to adenosine 5'-diphosphate was less in sutured than in clipped carotid arteries (P < 0.05), while there was no difference in maximal endothelium-independent relaxation to sodium nitrite. This result in clipped carotid arteries was not accompanied by less intimal hyperplasia. Screening of the aortic anastomotic line showed better preservation of endothelial architecture after clip anastomosis. Mean cross-clamp time for carotid patch repair was significantly less when using clips than with sutures. CONCLUSION: The use of non-penetrating clips for vascular anastomoses preserved endothelial function and structural integrity better than running sutures, although the degree of intimal hyperplasia was similar.

Anastomosis, Surgical↗

PubMed2000

Feasibility study on endoscopic suture with the combination of a distal attachment and a rotatable clip for complications of endoscopic resection in the large intestine.

BACKGROUND AND STUDY AIMS: Endoscopic resection has been more frequently performed for increasingly larger intramucosal tumors of the large intestine in recent years. It is reasonable to expect that the larger the resected mucosal surface, the greater is the likelihood of complications such as bleeding or perforation. The aim of this study was to explore the feasibility of endoscopic suture with a distal attachment and a rotatable clip-fixing device for complications of endoscopic resection in the large intestine. PATIENTS AND METHODS: The study population consisted of 15 patients who underwent endoscopic clipping therapy following endoscopic resection for intramucosal tumors of the large intestine. With a distal attachment fitted to the distal end of the endoscope, the optimal position for clipping was ensured by pressing the intestinal wall and deflating the intraluminal air little by little. With a rotatable clip-fixing device, the resection site was endoscopically sutured clip by clip. RESULTS: Tumors were of the laterally spreading tumor type in six patients, small sessile polyps in three, and pedunculated polyps in six. The complications consisted of bleeding in 12 patients, overt perforation in one, and latent perforation in two; 14 of the 15 patients underwent successful suturing by this method. The number of clips used ranged from two to seven (mean 4.4). No patients had further complications after the treatment. CONCLUSION: We conclude that endoscopic suture with the combination of a distal attachment and a rotatable clip-fixing device is very useful for complications of endoscopic resection in the large intestine.

Colonic Polyps↗

PubMed1996

Magnetic field gradients in the MRI suite and their effects on aneurysm clips.

We studied magnetic field intensity in the magnetic resonance imaging suite at our hospital and its possible effect on several different types of aneurysm clips, including one Heifetz 17-7 PH, six Heifetz Elgiloy, one Mayfield, six Perneczky, fifteen Sugita, one Sundt-Kees Variangle, four Variangle-McFadden and fifteen Yasargil clips. We carefully observed the clips for any translational or rotational movements along the path from the door towards the magnetic resonance imaging gantry. The magnetic field strength was 0.04 kiloGauss at the entrance of the room, with an acute increase of magnetic strength at 310 cm away from the entrance to the room, 90 cm to the entrance of the gantry. The magnetic strength continued to increase at a rate of 1.0-1.5 kiloGauss for every 20 cm up to the entrance to the gantry. No movement was observed in any of the clips at the entrance to the suite except for the Heifetz 17-7 PH clip, which showed small movement in the longitudinal plane of the clip. At the entrance to the gantry, the Heifetz 17-7 PH, Sundt-Kees Variangle, and Mayfield clips were aligned on the walls of the test container perpendicular to the magnetic bore. The, Heifetz Elgiloy, Perneczky, Sugita, Variangle-McFadden, and Yasargil clips showed no movement throughout the path of the stretcher or near the gantry.

Aneurysm↗

PubMed1988

Chronic angiotensin converting enzyme inhibition in the two-kidney, one clip hypertensive rat.

Treatment with an angiotensin converting enzyme (ACE) inhibitor in renovascular hypertension produces acute effects on renal function; however, the long-term consequences of this are not known. We have studied the effect of chronic enalapril treatment on renal structure and function in the two-kidney, one clip model of renovascular hypertension in the rat. Four weeks after the left renal artery was clipped, the hypertensive rats were randomly allocated to treatment with enalapril, minoxidil or to no treatment. The drug dose was titrated for maximal hypotensive effect. After 4 months of treatment blood pressures were 129 +/- 3 mmHg (enalapril), 193 +/- 5 mmHg (minoxidil) and 220 +/- 4.8 mmHg (no treatment). Twelve months later survival was 84% (enalapril group), 48% (minoxidil group) and 15% (untreated group). Split kidney function (51Cr-EDTA clearance, ml/min) of the clipped kidneys was 0.0 (enalapril group), 0.26 +/- 0.23 (minoxidil group) and 0.74 +/- 0.13 (untreated group). The clipped kidney from enalapril-treated rats weighed 0.46 +/- 0.1 g, much less than in the minoxidil-treated group (1.2 +/- 0.07) or the untreated group (1.14 +/- 0.10). Enalapril treatment was withdrawn for 2 weeks in five rats, but the clipped kidney remained small and non-functional. Histological examination revealed marked interstitial fibrosis and tubular atrophy in clipped kidneys from both enalapril groups, in contrast to minor changes in the minoxidil-treated and the untreated groups. We conclude that chronic enalapril treatment of two-kidney, one clip hypertension in the rat improved survival and preserved total renal function, but was associated with irreversible fibrotic atrophy of the clipped kidney.

Angiotensin-Converting Enzyme Inhibitors↗

PubMed2000

The expression of renin-binding protein and renin in the kidneys of rats with two-kidney one-clip hypertension.

OBJECTIVE: To test the hypothesis that renin-binding protein (RnBP) is involved in modulating the intracellular processing or release of renin, we examined the expression of RnBP in clipped and contralateral kidneys of rats with two-kidney one-clip hypertension, and in left and right kidneys from sham-operated control rats. DESIGN AND METHODS: Kidneys from rats with two-kidney one-clip hypertension and from control rats were either snap-frozen for extraction of mRNA or fixed for in-situ hybridization and immunochemistry. Reverse-transcription polymerase chain reaction on renal mRNA was performed using primers for renin, RnBP, glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and angiotensin-converting enzyme (ACE). In addition, renal total RNA was analysed by Northern blotting for RnBP, GAPDH and angiotensin II type 1A (AT1A) receptor mRNA, and the intensity of the bands was measured by laser densitometry. In situ hybridization for renin mRNA was carried out using digoxygenin-labelled antisense oligonucleotides and for RnBP using labelled antisense oligonucleotides and an antisense riboprobe. Controls included sections treated with RNase and sections stained with sense oligonucleotides. RESULTS: The level of expression of mRNA for RnBP is similar in clipped and contralateral kidneys of renal hypertensive rats; in contrast, renin mRNA expression is upregulated in the clipped kidney. Renin-binding protein is expressed mainly in renal tubules and collecting ducts unlike renin, which is expressed in the glomerular afferent arteriole. We did not detect lateralization of expression for ACE or the AT1A receptor between clipped and contralateral kidneys. CONCLUSION: Renin-binding protein expression is unchanged between clipped and contralateral kidneys. Therefore, a physiological stimulus that upregulates renin gene expression in clipped kidneys does not affect RnBP expression. The main sites of RnBP expression are the renal tubules and collecting ducts; in contast renin is expressed at the glomerular pole. The results show that RnBP is not colocalized or coregulated with renin in this model of hypertension.

Animals↗

PubMed1998

Cell-mediated allergy to a cerebral aneurysm clip: case report.

BACKGROUND AND IMPORTANCE: Titanium aneurysm clips have superior imaging characteristics and have been supplanting their stainless steel counterparts. We report the case of a 36-year-old woman with a histologically demonstrated cell-mediated reaction to a cobalt alloy aneurysm clip. CLINICAL PRESENTATION: The patient underwent a craniotomy and clip placement for a ruptured cerebral aneurysm. Both the aneurysm clip and the wires used to fix the craniotomy were made of stainless steel (cobalt and nickel) alloys. Postoperatively, the patient was plagued by intense pruritus. INTERVENTION: Skin patch testing revealed a severe reaction to nickel and cobalt. Surgical removal of the aneurysm clip and wires resulted in the disappearance of the patient's symptoms. A histological analysis of the tissue adjacent to the clip and wires was consistent with Type IV delayed type hypersensitivity. CONCLUSION: Stainless steel surgical implants in the head can cause diffuse, severe pruritus in susceptible individuals. Although the role of the aneurysm clip, as opposed to the more superficial wires, in the genesis of the patient's symptoms is not certain, this case demonstrates that a cobalt alloy aneurysm clip can activate T cells and cause an immunological reaction in the central nervous system.

Adult↗

PubMedDate not supplied

Evaluation of skin bacterial flora before and after aseptic preparation of clipped and nonclipped arthrocentesis sites in horses.

OBJECTIVE: This study evaluates skin bacterial flora before and after aseptic preparation of clipped and nonclipped arthrocentesis sites in horses. STUDY DESIGN: The hair over one midcarpal joint and one distal interphalangeal joint on each horse was clipped. The contralateral joint served as the nonclipped comparison. ANIMALS OR SAMPLE POPULATION: Twelve adult horses. METHODS: A prescrub sample for microbial culture was taken from the dorsal surface of all four joints for each horse. Each site was aseptically prepared with povidone iodine and 70% alcohol, followed by postscrub sampling for microbial culture. Colony forming units (CFUs) were determined for each sample, 24 hours after inoculation of blood agar plates. RESULTS: There was no significant difference (P > .05) in number of postscrub CFUs between clipped and nonclipped skin over the midcarpal or distal interphalangeal joints. Percent bacterial reduction (mean +/- SD%) after aseptic preparation differed significantly (P = .02) between clipped (99.8 +/- .003%) and nonclipped (96.2 +/- .05%) skin at the midcarpal joint, but not at the distal interphalangeal joint (clipped, 98.5 +/- .03% and nonclipped, 97.8 +/- 0.21%). There was a significant difference (P = .009) in number of prescrub CFUs obtained from clipped and nonclipped skin for the midcarpal joint. There was no significant difference in number of prescrub CFUs between clipped and nonclipped skin at the distal interphalangeal joint. Bacteria isolated from both clipped and nonclipped skin sampled postscrub included Bacillus sp, nonhemolytic Staphylococcus sp, and Micrococcus sp. CONCLUSIONS: The presence of hair over the midcarpal and distal interphalangeal joints does not appear to inhibit the ability of antiseptics to effectively reduce bacterial flora to an acceptable level for arthrocentesis. CLINICAL RELEVANCE: Aseptic preparation of the skin over the midcarpal and distal interphalangeal joints can be accomplished without hair removal in horses.

Animals↗

PubMed2000

Ligating clips for three-dimensional MR angiography at 1.5 T: in vitro evaluation.

Artifact size on three-dimensional (3D) magnetic resonance (MR) angiograms and safety of various vascular clips (15 titanium and three absorbable polydioxanone clips) were assessed. All evaluated clips were completely safe. Biodegradable clips rendered no artifacts; titanium clips were associated with susceptibility effects. Artifact size was dependent on clip size, clip orientation, echo time, and degree of k-space coverage. In the presence of titanium vascular clips, fast 3D MR angiography should be performed with the shortest echo time and full k-space coverage.

Artifacts↗

PubMed1983

Prevention of two-kidney, one-clip renal hypertension in rat by ablation of AV3V tissue.

This study examined the role of the anteroventral third ventricle (AV3V) in the renin-dependent two-kidney, one-clip model of renal hypertension. AV3V lesion and sham lesion rats were subjected to the placement of a clip on one renal artery or a sham operation. The sham lesion-renal artery clip rats experienced an increase in systolic blood pressure; however, AV3V lesioned animals experienced only a transient rise in arterial pressure during the 1st wk after clip. Body fluid regulation studies during the course of the hypertension revealed that there were no differences in water intake and urine volume between the lesion- and sham lesion-renal artery clip animals. Although significantly greater plasma and blood volumes were demonstrated in the AV3V lesion-sham clip rats compared with sham lesion animals, no differences in vascular volumes were detected in the renal artery clip rats. Finally, the rats were water deprived for 3 days to maximally stimulate vasopressin release. Urine osmolality increased significantly in all groups of rats except the AV3V lesion-renal artery clip animals protected against the hypertension.

Animals↗

PubMed1991

Renal atrial peptide receptors and natriuresis in two-kidney, one clip hypertension.

It has been suggested that the impaired natriuretic response of the clipped kidney in two-kidney, one clip hypertensive rats is related to downregulation of renal atrial natriuretic peptide receptors. To test this hypothesis, blood volume expansion and atrial peptide binding studies were performed in this model. Infusion of 1% and then 1.5% body weight donor blood (n = 6) caused a progressive increase in plasma immunoreactive atrial natriuretic peptide (107 +/- 26 to 168 +/- 31 to 427 +/- 154 pg/ml, p less than 0.001); the sodium excretion of the nonclipped kidney rose from 230 to 2,200 to 4,000 neq/min (p less than 0.01) but that of the clipped kidney did not rise significantly. There was a highly significant correlation between log cyclic guanosine monophosphate and log sodium excretion by the nonclipped (r2 = 0.749) but not the clipped (r2 = 0.046) kidney. Between clipped and nonclipped kidneys, the association constant (5.26 +/- 0.89 versus 5.17 +/- 0.64 x 10(9)/mol) and apparent binding site density (575 +/- 92 versus 500 +/- 74 fmol/mg protein) for atrial peptide binding in isolated glomeruli did not differ. Assay of atrial peptide-induced cyclic guanosine monophosphate release by isolated glomeruli showed that clipped and nonclipped kidneys were equally responsive. Binding affinity and receptor density did not differ in homogenates prepared from inner medullas of clipped and nonclipped kidneys. These results show that the blunted natriuretic response in clipped kidneys was not associated with any relative decrease in number or function of glomerular or papillary atrial natriuretic peptide receptors.

Animals↗

PubMed1984

Lack of evidence for the participation of tonin in the pathogenesis of one-kidney, one-clip renovascular hypertension.

It has been reported that immunization against tonin normalizes blood pressure, and that sialoadenectomy, during which the tonin-rich salivary glands are removed, decreases blood pressure in one-kidney, one-clip hypertension. To investigate the role of tonin on this form of hypertension further, we actively immunized one-kidney, one-clip hypertensive rabbits with tonin and measured both the blood pressure response and the titer of antibodies raised against tonin. In addition, because sialoadenectomy may alter food intake, we assessed the effect of sialoadenectomy on the blood pressure of one-kidney, one-clip hypertensive rats fed a liquid diet to facilitate eating. After immunization, all rabbits developed antitonin-antibody titers ranging from 1:300 to 1:56,000. However, in none of the rabbits did the blood pressure decrease significantly (114 +/- 3 mm Hg before immunization; 129 +/- 6 mm Hg at 16 weeks after immunization). In one-kidney, one-clip hypertensive rats, sialoadenectomy did not lower blood pressure (179 +/- 5 mm Hg before sialoadenectomy; 202 +/- 9 mm Hg 3 weeks after sialoadenectomy). Neither blood pressure nor body weight differed between sialoadenectomy and sham-sialoadenectomy one-kidney, one-clip hypertensive rats (n = 6). In conclusion, neither active immunization against tonin in one-kidney, one-clip hypertensive rabbits nor sialoadenectomy in one-kidney, one-clip hypertensive rats significantly reduced established hypertension. These results do not support the hypothesis that tonin is involved in the pathogenesis of one-kidney, one-clip hypertension in these animal models.

Animals↗

PubMed1985

Aneurysm clip motion during magnetic resonance imaging: in vivo experimental study with metallurgical factor analysis.

Because of various mechanical, metallurgical, and commercial constraints, aneurysm clips are manufactured from different alloys, including several stainless steel and cobalt alloys. Some of the steels contain volume fractions of the crystal phase known as martensite. Martensitic alloys have body-centered cubic structure, are prone to stress corrosion failure, and are ferromagnetic. Martensitic steel can be displaced like a compass needle when exposed to a magnetic field such as that generated during magnetic resonance imaging (MRI). The force exerted by the magnetic field is proportional to the volume fraction of the magnetic phase. We investigated the martensitic content and magnetic field-induced displacement of 12 common aneurysm clips. Four clips of each of the following types were examined: Sugita, Sundt-Kees Multi-Angle, Heifetz (two types), Vari-Angle McFadden, Yasargil (two types), Scoville, Mayfield, Vari-Angle, Pivot, and Kapp. Phase homogeneity and crystal structure were analyzed by x-ray diffraction using a Phillips x-ray diffractometer. Clip deflection in an Oxford Research Systems MRI spectrometer was measured in our in vivo rat abdominal aortic aneurysm model. Results showed that the volume fraction of the martensitic phase in the various clips correlated with the magnitude of the deflection. Among the clips examined, the Yasargil, Sugita, Heifetz Elgiloy, and Vari-Angle McFadden had a nonmartensitic composition and did not deflect in the magnetic field. The Scoville contained 5% martensite and deflected only marginally. Martensite comprised 35% of the Mayfield clip, which deflected 45 degrees, and 90% of the Heifetz, Vari-Angle, Pivot, and Sundt-Kees Multi-Angle clips, which deflected approximately 70 degrees or slipped off the aneurysm.(ABSTRACT TRUNCATED AT 250 WORDS)

Alloys↗

PubMed1994

Acute phase vascular endothelial injury: a comparison of temporary arterial occlusion using an endovascular occlusive balloon catheter versus a temporary aneurysm clip in a pig model.

We compared the degree of acute endothelial injury after temporary vessel occlusion using two different occlusion modalities--external clipping and endovascular balloon occlusion. The common carotid and subclavian arteries in eight weanling pigs were temporarily occluded with either a 5 Fr occlusion balloon catheter or a temporary microvascular clip for 0 (control), 5, 10, and 30 minutes. Two animals (eight vessels; four clip and four balloon occluded) were used at each time interval. Segments of each experimental vessel were harvested and analyzed by scanning electron microscopy. Each vessel specimen was graded on the following scale: Grade 1 showed no evidence of injury; Grade 2 showed minimal evidence of endothelial cell injury; Grade 3 showed moderate evidence of endothelial cell injury; Grade 4 showed marked evidence of endothelial cell injury; Grade 5 showed severe endothelial and subendothelial injury. Control vessels showed no evidence of injury. Grade 2 injuries were seen in both clip- and balloon-occluded vessels at 5 minutes. At 10 minutes, focal Grade 2 and 3 injuries were appreciated in the clip group, with diffuse Grade 2 and 3 injuries in the balloon group. After the 30-minute occlusion, the balloon group showed Grade 2, 3, and 4 injuries, whereas the clip group showed entirely Grade 2 injuries. The degree of injury with either occlusion modality was equivalent and worsened with time. However, clip-occluded vessels displayed injury that was confined to an area closely adjacent to the clip site, whereas balloon-occluded vessels demonstrated a more widespread injury centered around the balloon site.

Animals↗

PubMed1994

Molecular characterization of two functional domains of CLIP-170 in vivo.

CLIP-170 is a microtubule-binding protein isolated from HeLa cells that is involved in the interaction of endosomes with microtubules. The basic N-terminal domain of CLIP-170 binds to microtubules in vitro. To characterize further the functional domains of this cytoplasmic linker protein, we have transiently expressed intact and mutant forms of CLIP-170 in mammalian cells (HeLa and Vero cells) and show that the tandem repeat present in the N-terminal domain is essential for its binding to microtubules in vivo as previously found in vitro. With increasing levels of expression of CLIP-170, the sites with which the peripheral ends of microtubules interact enlarge, eventually forming large patches, which finally lead to the apparent bundling of microtubules. These patches do not form when the C-terminal domain is absent from the transfected protein. Modification of the microtubule-binding region, particularly of the tandem repeat motif, modulates the binding of CLIP-170 to microtubules. Overexpressed CLIP-170 appears neither to interact with nor to influence the organization of the intermediate filaments, and collapsing the network of intermediate filaments with microinjected antibodies against vimentin has no effect on the distribution of CLIP-170. These data suggest that CLIP-170 has at least two functional domains in vivo, an N-terminal microtubule-binding domain, and a C-terminal domain that is involved in the anchoring of microtubules to peripheral cytoplasmic structures.

Amino Acid Sequence↗

PubMed1999

Permissible arterial occlusion time in aneurysm surgery: postoperative hyperperfusion caused by temporary clipping.

The relationship between hyperperfusion and temporary clipping was evaluated to determine the safe limit for the duration of temporary clipping in aneurysm surgery. Twenty-one patients surgically treated for a ruptured aneurysm were examined using xenon-enhanced computed tomography on postoperative days 4 to 13. Eight of the 16 patients undergoing temporary clipping had focal hyperperfusion; whereas the five patients without temporary clipping had no hyperperfusion. Mean total temporary clipping time in patients with hyperperfusion was significantly longer than that in patients without (31.9 vs. 13.9 minutes, p = 0.0157) and mean maximum single temporary clipping time in patients with hyperperfusion was also significantly longer than in patients without (18.4 vs. 8.6 minutes, p = 0.0313). Moreover, cerebral infarction was related to hyperperfusion (p = 0.0027). These results support the hypothesis that temporary clipping during aneurysm surgery causes postoperative hyperperfusion and cerebral infarction. Temporary clipping may be harmful when performed for more than 20 minutes of total duration, since postoperative hyperperfusion was seen under this condition.

Adult↗

PubMed1984

Booster clips for giant and thick-based aneurysms.

The authors describe their experience using booster clips to secure the closure of primary clips in the repair of giant and other thick-walled aneurysms. These clips were used for 21 aneurysms in 20 patients, comprising 12% of all aneurysms operated on during the 15-month period of the report, but representing about 50% of all giant aneurysms operated on during the same time frame. These clips are designed to encircle the primary clip and have fixation "shoes" to close upon the jaws of the primary clip. All aneurysms were opened for decompression and thrombectomy when necessary following temporary major vessel occlusion before placement of the primary clip. Cerebral blood flow measurements and continuous electroencephalographic monitoring were utilized to predict the brain's tolerance to temporary ligation of the internal carotid artery (ICA) in those cases with a giant aneurysm arising from that vessel. There were no complications attributable to the periods of intracranial or cervical ICA occlusion; these periods varied but did not exceed 8 minutes for the former nor the tolerance period for the latter, which was calculated as from 5 to 30 minutes. It was necessary to reoperate on two patients and reposition clips because of stenoses or occlusions identified on immediate postoperative angiography. Fifteen patients had normal neurological function at the time of discharge. Three patients had minor deficits which did not prevent employment; two of these were related to a preoperative deficit and one was a complication of delayed ischemia. There were two deaths: one from bleeding complications and probable damage to perforating vessels in a patient operated on under profound hypothermia (the only case in the series so managed), and one from respiratory complications in a patient with severe pulmonary problems.

Adult↗

PubMed1989

Magnetic resonance imaging and aneurysm clips. Magnetic properties and image artifacts.

The magnetic properties of 12 different types of aneurysm clip were investigated in order to identify which clips allow postoperative magnetic resonance (MR) imaging without risk. Clip-induced MR artifacts were also quantitatively studied using a geometrical phantom. Nonferromagnetic aneurysm clips like the Yaşargil Phynox, Sugita Elgiloy, and Vari-Angle McFadden clips do not appear to contraindicate MR studies performed with a FONAR beta-3000M imager. There is no clip movement upon introduction of the phantom into the MR imager, and the image artifacts caused by the clips are so limited that patients harboring such clips may well be considered for MR imaging. This examination may reveal information not obtainable by any other radiological modality.

Aneurysm↗