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Biomedical subjects

W Yu

Publications and source records attributed to W Yu.

At least 181 records · Page 10Linked to original sources
PubMed1998

Long-term alleviation of allodynia-like behaviors by intrathecal implantation of bovine chromaffin cells in rats with spinal cord injury.

Adrenal chromaffin cells produce analgesic substances, such as catecholamines and enkephalins, and intrathecal (i.t.) implantation of either allografted adrenal tissue or xenogenic chromaffin cells produce antinociception in animals. We evaluated the analgesic effect of bovine chromaffin cells in a model of central pain in which rats exhibit chronic allodynia-like behavior after photochemically induced ischemic spinal cord injury. Bovine chromaffin cells or endothelial cells were injected i.t. onto the lumbar spinal cord and their effects on mechanical and cold allodynia-like behaviors were studied for up to 8 weeks. The chronic allodynia-like behavior was stable for months without signs of remission and i.t. implantation of human endothelial cells did not alleviate the chronic allodynia-like behavior for the entire observation period. In contrast, 2 weeks after i.t. implantation of bovine chromaffin cells, the mechanical allodynia was abolished in the spinally injured rats, and the enhanced response to cold stimuli was significantly reduced. The overall effects were significant up to 8 weeks after i.t. implantation, although the anti-allodynic effect decreased towards the end of the observation period. No signs of side-effects were noted after i.t. implantation. The allodynia-like state was temporarily restored by naloxone (0.5 mg/kg) or phentolamine (0.3 mg/kg) injected intraperitoneally. Immunohistochemical examination revealed that tyrosine hydroxylase (TH)-positive chromaffin cells could be identified adjacent to the spinal cord up to 4 weeks after i.t. implantation, whereas at 8 weeks the TH-positive cells were sparse. It is concluded that bovine chromaffin cells stay viable in rat spinal cord for a considerable period of time after i.t. administration and alleviate chronic allodynia-like behavior in spinally injured rats, possibly through activation of opioid and alpha-adrenoceptors. The present results further document a new therapeutic approach for the treatment of chronic neuropathic pain.

Animals↗
PubMed1998

Treatment of chronic allodynia in spinally injured rats: effects of intrathecal selective opioid receptor agonists.

We examined the effects of intrathecal (i.t.) selective opioid receptor agonists in alleviating mechanical and cold allodynia in spinally injured rats. Both DAMGO ([D-Ala2,N-Me-Phe4,Gly5-ol]-enkephalin, a mu-opioid receptor agonist) and DPDPE ([D-Phe2,D-Phe5]-enkephalin, a delta-opioid receptor agonist) dose-dependently relieved the chronic allodynia-like behavior at doses selective for their respective receptors. The anti-allodynic effect of DAMGO and DPDPE was reversed by the selective mu- and delta-opioid receptor antagonists CTOP (D-Phe-Cys-Tyr-D-Trp-Orn-Thr-Pen-Thr-NH2) and naltrindole, respectively. In contrast, the selective kappa-opioid receptor agonist U50488H did not alleviate the allodynia-like behavior, but rather enhanced it. The anti-nociceptive and anti-allodynic effect of i.t. DAMGO was blocked by U50488H. Thus, activation of spinal mu- and delta-, but not kappa-opioid receptors produced anti-allodynic effect in this model of central pain. Drugs which act selectively on opioid receptor subtypes may be useful in managing chronic central pain of spinal cord origin.

3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cycloh↗
PubMed1998

Photochemically-induced ischemia of the rat sciatic nerve produces a dose-dependent and highly reproducible mechanical, heat and cold allodynia, and signs of spontaneous pain.

Sensory abnormalities and changes in spontaneous behavior were examined after a photochemically induced ischemic lesion of the rat sciatic nerve. Male adult rats were anesthetized and the sciatic nerve was exposed. After the intravenous injection of a photosensitizing dye, erythrosin B, the exposed nerve was irradiated just proximal to the nerve trifurcation with light from an argon laser. Three different irradiation times were used, 30 s, 1 and 2 min. In sham-operated rats, the exposed sciatic nerve was irradiated for 2 min without prior injection of the erythrosin B. Rats were tested for the presence of mechanical, cold and heat allodynia or hyperalgesia. All the animals in the 1- and 2-min irradiation groups developed mechanical, cold and heat allodynia after nerve irradiation. A significant dose-dependent effect of laser exposure time was observed for all modalities tested (2 min > 1 min > 30 s = sham). The maximum effects were observed at 3 and 7 days postirradiation and remained present for up to 10 weeks. No significant contralateral effects were observed in any of the groups. In three separate groups of rats (1, 2 and 4 min of laser exposure), the presence of possible signs of spontaneous pain (paw shaking, paw elevation and freezing behavior) was tested. A significant and exposure time-dependent increase in spontaneous paw elevation and paw shaking was observed which was maximal at week 1, but resolved at 4 weeks (4 min > 2 min > 1 min > sham). In addition, animals in all ischemic groups, but not in the sham group, showed a significant increase in freezing behavior up to 4 weeks after nerve irradiation. Light microscopic evaluation of nerves removed 7 days post-irradiation, i.e. when maximal allodynia was observed, showed clear evidence of demyelination of large myelinated fibers. These data indicate that photochemically-induced peripheral nerve ischemia is associated with abnormal pain-related behaviors, including mechanical, thermal and cold allodynia and signs of spontaneous pain. The incidence and severity of the behavioral changes are clearly dependent on the exposure time and are probably due to, at least in part, a demyelinaton. These results partly confirm previous data using a similar technique and suggest that this may represent a new animal model for peripheral neuropathy of ischemic origin. The advantages of the present model are its good reproducibility and the fact that the nerve injury can be easily quantified and graded.

Animals↗
PubMed1998

Concurrent comparison of endoluminal versus open repair in the treatment of abdominal aortic aneurysms: analysis of 303 patients by life table method.

PURPOSE: The aim of this study was to compare the outcome of consecutive patients with abdominal aortic aneurysm (AAA) treated concurrently by open operation and endoluminal intervention by the same surgeons during a defined interval. METHODS: Between May 1992 and May 1996, 362 consecutive patients with AAA underwent repair. Fifty-three patients who underwent open operations for ruptured AAA plus two patients who underwent endoluminal repair of false AAA and four patients who underwent secondary endoluminal repair of AAA were excluded, leaving 303 patients who underwent elective repair of true AAA in the study. The elective operations were conventional open repair (OR) in 195 patients (151 men, 44 women; mean age, 69 years) and endoluminal repair (ER) in 108 patients (100 men, 8 women; mean age, 70 years). The decision to perform ERwas based on comorbidities that precluded open repair (n = 48) and patient choice (n = 60). Graft configuration in the open repair group was tubular (n = 180) and bifurcated (n = 15), and in the ER group tubular (n = 48), aortoiliac/femoral (n = 25), and bifurcated (n = 35). All procedures were performed in the operating department, and radiographic guidance was used in the ER group. Follow-up was by interview, examination, and telephone. In addition, contrast-enhanced computed tomography was performed within the first 10 days after operation, 6 months and 12 months after operation, and then annually thereafter in the ER group. Outcome measures were successful exclusion of the aneurysm sac from the general circulation and survival. Data were analyzed by the life table method. Other outcome measures were length of hospital stay, length of intensive care unit stay, and operative blood loss. RESULTS: No significant difference was found between the perioperative mortality rate for OR (11 deaths [5.6%] in 195 patients) and ER (six deaths [5.6%] in 108 patients). Three of the six deaths in the latter group occurred in patients with successful ER, and three occurred in 18 patients with failed ER who were converted to OR. Similarly, no significant difference was seen in the survival rate between the endoluminal and open repair groups when analyzed by the log-rank test (p = 0.14). The rate of graft failure, however, was significantly higher in the ER group than in the OR group (Fisher's exact test, p < 0.001). Success in the ER group was defined as continuing graft function without endoleak or conversion to open repair. Kaplan-Meier curve for graft failure times for the endoluminal group revealed a 3-year graft success probability of 70%. CONCLUSIONS: This study suggests that ER is safe, sharing the same perioperative mortality risk as OR despite 44% of the ER group being rejected as unfit for OR. Conventional open repair is the most reliable method of successfully managing AAA. The endoluminal method, however, results in shorter length of hospital stay, shorter length of intensive care unit stay, and less blood loss than the open method. Patients who opt for the endoluminal method of repair should be made aware that the minimally invasive technique carries the disadvantage of a higher failure rate.

Aged↗
PubMed1998

Endovascular grafting for abdominal aortic aneurysms: changing incidence and indication for conversion to open operation.

The incidence and indications for conversion from endoluminal to open repair of abdominal aortic aneurysms are changing. This paper is based on a 5-year experience in which endoluminal repair of abdominal aortic aneurysms was undertaken in 156 patients. Primary conversion at the original operation was required in 14 patients and secondary conversion at a subsequent operation was required in 9 patients. The reasons for primary conversion were access problems (n = 2), balloon related problems (n = 2), endograft migration (n = 4), endograft thrombosis (n = 1) and failed deployment of a bifurcated endograft (n = 5). Twelve of 14 primary conversions occurred in the first half of the study period, in which 59 endoluminal abdominal aortic aneurysms repairs were undertaken. Improvements in technology and interventional techniques for overcoming obstacles, as well as increasing experience, has resulted in primary conversion being limited to two patients in the most recent 2.5-year period in which 97 endoluminal repairs were undertaken. The reasons for secondary conversion were renal arteries covered by the endograft (n = 2), increasing abdominal aortic aneurysm diameter in the absence of endoleak (n = 1) and persistent endoleak (n = 6). The latter group comprised three patients with intact aneurysms and three with known endoleaks who presented with ruptured aneurysms. The current indications for primary conversion include: (i) rupture of the aorta; (ii) complete migration of the endograft resulting in obstruction of the iliac arteries; and (iii) irreversible twisting of a non-modular bifurcated endograft. The current indications for secondary conversion include: (i) persistent endoleak; (ii) sealed endoleak with continued abdominal aortic aneurysms expansion; (iii) apparently successful endoluminal repair without evidence of endoleak but continued abdominal aortic aneurysms expansion; and (iv) infected endograft.

Aortic Aneurysm, Abdominal↗
PubMed1998

Evaluation of the risks of using an oversized balloon catheter in the human infrarenal abdominal aorta.

OBJECTIVES: To evaluate the effects on the aortic wall of balloon dilatation as utilised in deployment of stent-graft devices during endoluminal repair of infrarenal abdominal aortic aneurysm. METHODS: Large dilatation balloons were expanded within the aorta of 41 cadavers. Testing was done to evaluate the effect of differing degrees of balloon oversizing, at pressures in the range of 0.15-2.5 atm. The aorta was then open for macroscopic inspection. RESULTS: In group 1 (mild atherosclerosis) no macroscopic abnormalities were detected with up to 6 mm oversized balloon. In group 2 (moderate atherosclerosis) fracture of atherosclerotic plaque occurred in seven of 14 aortas (50%) with 2.5 mm-4mm oversized balloon. In group 3 (severe atherosclerosis) fracture of atherosclerotic plaque occurred in six of seven (85%) with 2.5 mm to 4 mm oversized balloon and rupture of the aorta occurred at 6 mm oversizing. CONCLUSIONS: This study suggests that balloon overdilatation of the aorta by 2 mm, at pressures less than 2 atmospheres, allows safe deployment even in the presence of severe atheroma. Larger amounts of overdilatation are relatively safe in mildly atherosclerotic aorta. Aortic rupture is unlikely with overdilatation up to 6 mm, especially in less calcified vessels.

Adolescent↗
PubMed1998

Importance of graft configuration in outcome of endoluminal aortic aneurysm repair: a 5-year analysis by the life table method.

AIM: The aim of this study was to determine the influence of graft configuration on the outcome of endoluminal repair of abdominal aortic aneurysm (AAA). METHODS: The 5-year study period extended from May 1992 to May 1997 and included analysis of patients undergoing endoluminal AAA repair in the first 4.5-year period with a minimum follow-up period of 6 months. Between May 1992 and November 1996 136 patients underwent endoluminal AAA repair. Two patients who had endoluminal repair of anastomotic AAA and six patients who had secondary endoluminal repair of AAA were excluded, leaving 128 patients in the study group. There were 117 males and 11 females with a mean age for the group of 71 years. The configuration of the grafts was tubular aortic (T) (n = 50), tapered aortoiliac/femoral (AI) (n = 24) and bifurcated (B) (n = 54). Patient characteristics and co-morbidities were similar in the three groups. The procedures were performed in the operating room under radiographic control. Follow-up was complete and consisted of regular physical examination and contrast enhanced computed tomography. Outcome measures were perioperative mortality rate, need for conversion to open repair, presence of early and late endoleaks, successful exclusion of AAA from the circulation, and survival. Data were analysed by the life table method. RESULTS: There was no significant difference in perioperative mortality for T (4%), AI (4%) and B (5.5%) configuration of endograft. Outcome for T, AI, and B configurations was respectively: primary conversion (%) 8, 12, 13; early endoleaks (n =) 5, 0, 1; late endoleaks (n =) 7, 0, 1. The overall incidence of failed procedures throughout the study period was higher in tube grafts compared with non-tube (aortoiliac and bifurcated) grafts (p < 0.05). Kaplan-Meier curves demonstrated a success probability at 40 months of 50% for tube grafts and 80% for non-tube grafts. However, a comparison of the time to procedure failure between tube versus non-tube after adjusting for competing risks (death without prior graft failure) was non-significant (p = 0.14). CONCLUSIONS: The poor mid-term outcome for tube prostheses requires a reassessment of the criteria for selecting this configuration. It would be unwise to abandon the use of tube prostheses entirely in endoluminal repair. With increasing information on mid and long-term outcome of endoluminal AAA repair it is likely that there will be an increasing acceptance of treating smaller AAA while they are still suitable for treatment by the endoluminal method and most likely with tube grafts. A tightening of the criteria for using tube prostheses would seem sensible. In particular, the minimum length of distal neck required for endoluminal tube graft repair should be increased to the 2-2.5 cm range.

Aged↗
PubMed1998

Immunoisolating encapsulation of intrathecally implanted bovine chromaffin cells prolongs their survival and produces anti-allodynic effect in spinally injured rats.

We have previously reported that intrathecal (i.t.) implantation of bovine chromaffin cells has an anti-allodynic effect in a rat model of mechanical and cold allodynia-like neuropathic pain after spinal cord injury. The technique of encapsulation of the cells by a semipermeable membrane has been developed recently. The present study was undertaken to investigate the effects of encapsulated bovine chromaffin cells on the allodynia-like pain in the same model. Capsules with bovine chromaffin cells or control capsules were implanted in the spinal subarachnoidal space in rats. Their response in behavioural tests were recorded for 2 months. At termination, the capsules were explanted and examined morphologically with tyrosine hydroxylase immunohistochemistry. The mechanical allodynia was totally abolished from week 2 after implantation of the cells and throughout the 8-week test period. The abnormal cold response was also attenuated in about half of the animals. The threshold to acute nociceptive stimulation was not affected. Eight weeks after implantation, 60-80% of the encapsulated chromaffin cells were still tyrosine hydroxylase positive. No effects were observed with control capsules. The results indicate that spinal implantation of encapsulated xenogeneic chromaffin cells may be useful in treating some refractory painful states associated with spinal cord injury. Immunoisolation of chromaffin cells by a semipermeable membrane may inhibit immunorejection, prolong the survival of the cells and enhance their anti-allodynic effect. Copyright 1998 European Federation of Chapters of the International Association for the Study of Pain.

Journal Article↗
PubMed1998

Classification of the frog lingual gland cells and their exocytotic features.

We examined under light and electron microscopes the frog lingual gland before and after acetylcholine-stimulation. The lingual gland is composed of five kinds of secretory cells (type 1-5) and ciliated cells. Each secretory cell had numerous cell-type characteristic secretory granules, probably in which both serous and mucous secretory products were contained. The ciliated cells had lysosomes, cytoplasmic filaments and on their apical surface microvilli in addition to cilia. Two kinds of exocytotic features were demonstrated in the secretory cells. One of them, termed multigranular exocytosis, was whole-cell discharge of secretory products in which intracellular huge vacuoles continuous to the cell exterior were formed as the result of multiple granule-to-granule fusion as well as granule-to-plasma membrane fusion. The other type was local exocytotic release of a single or a few secretory granules near the plasma membrane. The multigranular exocytosis was restricted to type 4 and 5 secretory cells while single or a few granular exocytosis was seen in type 1, 2, 4 and 5 secretory cells. This may be because secretory granules are larger and more closely packed in type 4 and 5 secretory cells than in other types of secretory cells. Type 3 secretory cells contained abundant cytoplasmic filaments, and showed no exocytotic feature, suggesting transitional cells between secretory cells and ciliated cells.

Acetylcholine↗
PubMed1998

Prospective randomized trial of early postoperative intraperitoneal chemotherapy as an adjuvant to resectable gastric cancer.

OBJECTIVE: Surgeons have postulated on numerous occasions that cancer resection may participate in the dissemination of a malignancy. This randomized trial sought to determine whether a large volume of chemotherapy solution used perioperatively to flood the peritoneal cavity could eliminate microscopic residual disease and thereby improve survival of patients with gastric cancer. SUMMARY BACKGROUND DATA: Surgical treatment failures in patients with gastric cancer are confined to the abdomen in most patients. Resection site and peritoneal surface spread, along with liver metastases, are the most common areas of recurrence. Survival and quality of life of patients with gastric cancer would be improved if disease progression at these anatomic sites was reduced. METHODS: In a prospective randomized trial of 248 patients, intraperitoneal mitomycin C on day 1 and intraperitoneal 5-fluorouracil on days 2 through 5 were administered after gastric cancer resection. Patients who were thought to have stage II or stage III disease were randomized after resection to surgery alone versus surgery plus early postoperative intraperitoneal chemotherapy. After final pathologic examinations, there were 39 patients with stage I, 50 with stage II 95 with stage III, and 64 with resected stage IV cancer. RESULTS: The 5-year survival of the surgery-only group was 29.3%, and the surgery-plus-intraperitoneal chemotherapy group was 38.7% (p = 0.219). In a subset analysis, the patients with stage I, stage II, and stage IV disease showed no statistically significant difference in survival. The 5-year survival rate of patients with stage III disease who underwent surgery only was 18.4% versus a survival rate of 49.1% for patients who underwent surgery plus intraperitoneal chemotherapy (p = 0.011). CONCLUSIONS: In a subset analysis, patients with stage III gastric cancer have shown a statistically significant improvement in survival when treated with perioperative intraperitoneal chemotherapy. Further studies in patients with gastric cancer with surgically directed chemotherapy are suggested.

Adult↗
PubMed1998

Endoluminal repair: a better option for the treatment of complex false aneurysms.

BACKGROUND: The aim of the present paper is to present the utility of endoluminal repair in the management of complex false aneurysms at various sites throughout the body. METHODS: Between May 1992 and May 1997 the endoluminal method was used to repair 183 aneurysms at various sites throughout the body. In six patients the pathology was that of false aneurysm and these are the basis of the present report. In two of the patients the false aneurysm was situated between the renal arteries and the proximal end of a previous aortic graft. The other false aneurysms were situated in the right subclavian, the popliteal and internal carotid arteries, in addition to one situated at the junction of two longstanding bypass grafts in the groin. The technique involved delivery of an endograft into the artery from which the false aneurysm had arisen via a sheath inserted through an artery of access which was superficial and remote from the site of the aneurysm. A laparotomy was avoided in the first two cases and thoracotomy avoided in the third case. Opening of the popliteal fossa, which had been the site of a recent knee replacement in the fourth patient, was also avoided. RESULTS: Post-procedure angiography confirmed exclusion of the false aneurysm from the general circulation in all six patients. There were no deaths and the mean length of hospital stay was 6 days. CONCLUSIONS: Endoluminal repair of false aneurysms is feasible and avoids the difficulty and morbidity associated with laparotomy, thoracotomy and operations at sites with scarring from previous interventions.

Aged↗
PubMed1998

Measurements of the neutron yields from 7Li(p,n)7Be reaction (thick target) with incident energies from 1.885 to 2.0 MeV.

Accelerator-based neutron source have been considered to be practical for boron neutron capture therapy (BNCT). Based on experience with a parameters of the Brookhaven National Laboratory BMRR reactor neutron source, which has been used in treatment experiments, the future accelerator-based neutron source for BNCT should have the properties of low energy distribution (< 100 keV) and high flux (about 10(9) neutrons per second per square centimeter) in the patient zone. Using protons to bombard thick 7Li targets, generating neutrons via the 7Li(p,n)7Be reaction, is one of the optimal choices for this kind of neutron source. Neutron yield data versus incident energy are necessary in order to select the proper incident energy and for estimating how high the incident proton current should be. The required proton beam current intensity is one of the key parameters for an accelerator useful for BNCT. In the present work, neutron yields of the 7Li(p,n)7Be reaction with a thick lithium target and incident energies of 1.885 and 1.9 MeV were measured at 0 degree with respect to the incident beam direction. The results are (3.08 +/- 0.17) x 10(12) and (5.71 +/- 0.32) x 10(12) neutrons/C sr, respectively. Neutron yield angular distribution measurements at 2 MeV incident energy were also performed. The proton beams were generated by the Peking University 4.5 MV electrostatic accelerator. The emitted neutrons from these reactions have the advantages of low energy distribution and forward angular distribution, which are requirements for a BNCT neutron source. The data obtained in this work can be used as a reference to study the accelerator-based neutron sources for BNCT.

Beryllium↗
PubMed1998

A deficiency in aspartate biosynthesis in Lactococcus lactis subsp. lactis C2 causes slow milk coagulation.

A mutant of fast milk-coagulating (Fmc+) Lactococcus lactis subsp. lactis C2, designated L. lactis KB4, was identified. Although possessing the known components essential for utilizing casein as a nitrogen source, which include functional proteinase (PrtP) activity and oligopeptide, di- and tripeptide, and amino acid transport systems, KB4 exhibited a slow milk coagulation (Fmc-) phenotype. When the amino acid requirements of L. lactis C2 were compared with those of KB4 by use of a chemically defined medium, it was found that KB4 was unable to grow in the absence of aspartic acid. This aspartic acid requirement could also be met by aspartate-containing peptides. The addition of aspartic acid to milk restored the Fmc+ phenotype of KB4. KB4 was found to be defective in pyruvate carboxylase and thus was deficient in the ability to form oxaloacetate and hence aspartic acid from pyruvate and carbon dioxide. The results suggest that when lactococci are propagated in milk, aspartate derived from casein is unable to meet fully the nutritional demands of the lactococci, and they become dependent upon aspartate biosynthesis.

Animals↗
PubMed1998

Association between corticosteroid use and vertebral fractures in older men with chronic obstructive pulmonary disease.

Osteoporosis is a major complication of long-term corticosteroid administration, but the magnitude of the effect in patients with chronic obstructive pulmonary disease (COPD) is not well defined. In a cross-sectional study, we evaluated the association between steroid use and vertebral fractures in 312 men, 50 yr of age or older, with COPD. Subjects were evaluated according to their corticosteroid use: Never Steroid Users (NSU) (n = 117), Inhaled Steroid Users (ISU) (n = 70), and Systemic Steroid Users (SSU) (n = 125). The prevalence of one or more vertebral fractures was 48.7% in the NSU group, 57.1% in the ISU group, and 63.3% in the SSU group. Compared with NSU, SSU were two times as likely to have one or more vertebral fractures: age-adjusted odds ratio (OR) = 1.80; 95% CI, 1.08 to 3.07. This relationship was primarily due to a strong association between continuous systemic steroid use and vertebral fractures: age-adjusted OR = 2.36; 95% CI, 1.26 to 4.38. In addition, fractures in SSU were more likely to be multiple and more severe. A weaker relationship existed between inhaled steroid use and vertebral fractures: age-adjusted OR = 1.35; 95% CI, 0.77 to 2.56 compared with NSU. These data indicate that vertebral fractures are common in older men with COPD; the likelihood of these fractures is greatest in those men using continuous systemic steroids.

Administration, Inhalation↗
PubMed1998

Type III and type IV endoleak: toward a complete definition of blood flow in the sac after endoluminal AAA repair.

In this document the authors continue to refine their seminal categorization of endoleak, a major complication of endovascular aneurysm repair. In addition to type I (related to the graft device itself) and type II (retrograde flow from collateral branches) endoleak, they propose two new categories: endoleak due to fabric tears, graft disconnection, or disintegration would be classified type III, and flow through the graft presumed to be associated with graft wall "porosity" would be categorized as type IV endoleak.

Aortic Aneurysm, Abdominal↗
PubMed1998

Diameter of large balloons used in endoluminal graft deployment varies with inflation pressure.

PURPOSE: To evaluate the characteristics of large-diameter balloon catheters used during endoluminal repair of aortic aneurysms. METHODS: Thirty-three large balloon dilatation catheters in the diameter range of 15 to 30 mm were measured at controlled pressures from 1 to 4 atm. The balloons were inflated with water using an inflation syringe connected to a pressure transducer. Diameters at stable pressure and pressure changes against time were recorded for each balloon. RESULTS: Dilation catheters in the range of 15 to 20 mm in diameter were significantly smaller (p < 0.005) than their nominal diameter at 1 and 2 atm; they reached nominal diameter only at the relatively high pressure of 4 atm. Most larger diameter balloons (25 and 30 mm) did not attain their nominal diameter even with pressures up to 4 atm. All sizes of balloon catheters tested became relatively compliant at pressures > 3 atm. CONCLUSIONS: The large balloon catheters tested in this study were designed for arterial angioplasty or valvuloplasty. They attained a significantly smaller size than their nominal diameter at pressures < 3 atm and became compliant at pressures exceeding 3 atm. Interventionists should be aware of these characteristics when using balloon catheters such as these during endoluminal graft deployment. Large balloons that reach predictable diameter at lower pressures should be designed specifically for use in endoluminal graft procedures.

Aortic Aneurysm↗