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Biomedical subjects

P L Faries

Publications and source records attributed to P L Faries.

13 recordsLinked to original sources
PubMed1998

Endoleak after endovascular graft repair of experimental aortic aneurysms: does coil embolization with angiographic "seal" lower intraaneurysmal pressure?

PURPOSE: To investigate the relation between endoleaks and intraaneurysmal pressure (IAP) and the effect of coil embolization in the management of endoleaks. METHODS: The infrarenal aorta of a dog (n = 15) was replaced by a polytetrafluoroethylene aneurysm containing a pressure transducer. Group I (n = 4) had untreated aneurysms. Group II (n = 4) had endovascularly excluded aneurysms without an endoleak. Group III (n = 7) had aneurysms excluded by means of grafts with a defect that represented the source of an endoleak. After 4 weeks of follow-up study, the endoleaks in group III dogs were subjected to coil embolization. Systolic IAP was measured daily and expressed as a ratio of systolic blood pressure obtained from a forelimb cuff. Arteriography, duplex ultrasonography, and spiral contrast computed tomography were performed to evaluate endoleaks. RESULTS: In group I, the LAP remained close to systolic blood pressure (ratio of 0.96 +/- 0.06), whereas in group II the IAP ratio showed a decline to 0.34 +/- 0.16 (p = 0.0009 group I versus II). After an initial decrease, the IAP ratio in group III stabilized at 0.75 +/- 0.18 (p = 0.003, group II versus III). Aneurysms with an endoleak remained pulsatile with a pulse pressure of 30 +/- 16 mm Hg, which was less than that of untreated aneurysms (62 +/- 15 mm Hg; p < 0.0001 group I versus III). Arteriography and computed tomography revealed "sealing" of endoleaks after coil embolization, but IAP ratio did not decrease (0.76 +/- 0.14) after coil embolization. CONCLUSIONS: Incomplete endovascular aneurysm exclusion caused by an endoleak fails to reduce IAP ratio and may subject the aneurysm to a continued risk for rupture. Although coil embolization resulted in angiographic and computed tomographic sealing, it failed to reduce IAP ratio.

Aneurysm, False↗
PubMed1998

Ex vivo human carotid artery bifurcation stenting: correlation of lesion characteristics with embolic potential.

PURPOSE: To develop an ex vivo human carotid artery stenting model that can be used for the quantitative analysis of risk for embolization associated with balloon angioplasty and stenting and to correlate this risk with lesion characteristics to define lesions suitable for balloon angioplasty and stenting. METHODS: Specimens of carotid plaque (n = 24) were obtained circumferentially intact from patients undergoing standard carotid endarterectomy. Carotid lesions were prospectively characterized on the basis of angiographic and duplex findings before endarterectomy and clinical findings. Specimens were encased in a polytetrafluoroethylene wrap and mounted in a flow chamber that allowed access for endovascular procedures and observations. Balloon angioplasty and stenting were performed under fluoroscopic guidance with either a Palmaz stent or a Wallstent endoprosthesis. Ex vivo angiograms were obtained before and after intervention. Effluent from each specimen was filtered for released embolic particles, which were microscopically examined, counted, and correlated with various plaque characteristics by means of multivariate analysis. RESULTS: Balloon angioplasty and stenting produced embolic particles that consisted of atherosclerotic debris, organized thrombus, and calcified material. The number of embolic particles detected after balloon angioplasty and stenting was not related to preoperative symptoms, sex, plaque ulceration or calcification, or artery size. However, echolucent plaques generated a higher number of particles compared with echogenic plaques (p < 0.01). In addition, increased lesion stenosis also significantly correlated with the total number of particles produced by balloon angioplasty and stenting (r = 0.55). Multivariate analysis revealed that these two characteristics were independent risk factors. CONCLUSIONS: Echolucent plaques and plaques with stenosis > or = 90% produced a higher number of embolic particles and therefore may be less suitable for balloon angioplasty and stenting. This ex vivo model can be used to identify high-risk lesions for balloon angioplasty and stenting and can aid in the evaluation of new devices being considered for carotid balloon angioplasty and stenting.

Angioplasty, Balloon↗
PubMed1998

Intestinal permeability correlates with severity of injury in trauma patients.

BACKGROUND: Increased intestinal permeability (IP) and the release of toxic intraluminal materials have been implicated in the systemic inflammatory response syndrome (SIRS) and multiple organ failure (MOF) observed in patients after severe trauma. Previous studies of intestinal permeability have failed to demonstrate a correlation between early measurements of IP and indicators of injury severity. This study examines the relationship between standard measures of injury severity and the early (day 1) and delayed (day 4) changes in IP. Associations between IP and the development of SIRS, MOF, and infectious complications were also studied. METHODS: The metabolically inactive markers lactulose (L) and mannitol (M) were used to measure IP in 29 consecutive patients who sustained injuries that required admission to the surgical intensive care unit and in 10 healthy control subjects. Measurements were made within 24 hours of admission and on hospital day 4. Severity of injury was assessed by A Severity Characterization of Trauma (ASCOT), Trauma and Injury Severity Score (TRISS), Injury Severity Score (ISS), Revised Trauma Score (RTS), and Acute Physiology and Chronic Health Evaluation (APACHE) II score. Postinjury infections and parameters of SIRS and MOF were recorded. RESULTS: The IP of healthy volunteers (L/M, 0.025 +/- 0.008) was within the normal range (L/M < or = 0.03), whereas the average IP in injured patients was increased both within 24 hours (L/M, 0.139 +/- 0.172) and on the fourth hospital day (L/M, 0.346 +/- 0.699). No significant correlation between severity of injury and increased IP was seen within 24 hours of injury. A significant correlation was seen on hospital day 4, however, with all severity indices measured (ASCOT: r = 0.93, R2 = 0.87, p < 0.001; TRISS: r = 0.93, R2 = 0.87, p < 0.001; ISS: r = 0.84, R2 = 0.70, p < 0.001; RTS: r = 0.68, R2 = 0.47, p = 0.002; APACHE II score: r = 0.51, R2 = 0.26, p = 0.04). Patients with markedly increased IP (L/M > or = 0.100) experienced a significant increase in the development of SIRS (83 vs. 44%; p = 0.03) and subsequent infectious complications (58 vs. 13%; p = 0.01) and showed close correlation with the multiple organ dysfunction scores (r = 0.87, R2 = 0.76, p < 0.001). CONCLUSION: These observations demonstrate that the increased IP observed after trauma correlates with severity of injury only after 72 to 96 hours and not within the initial 24 hours of injury. A large increase in IP is associated with the development of SIRS, multiple organ dysfunction, and an increased incidence of infectious complications.

Case-Control Studies↗
PubMed1998

Seat belt injury presenting as bilateral abdominal wall herniations in a child.

The constellation of abdominal injuries caused by seat belts in automobile accidents usually consists of intraabdominal solid organ and hollow viscus injuries. We present a two-and-one-half-year-old patient with an unusual constellation of seat belt injuries that presented as bilateral abdominal herniations. We feel that an abdominal hernia caused by a seat belt injury should alert the clinician to the probability of other severe intraabdominal injuries. The uniqueness of this case is compounded by the way in which the seat belt was misused.

Abdominal Injuries↗
PubMed1997

Chronic intraaneurysmal pressure measurement: an experimental method for evaluating the effectiveness of endovascular aortic aneurysm exclusion.

PURPOSE: To evaluate and compare the intraaneurysmal pressure (IAP) after exclusion using two different endovascular grafts. METHODS: Eight mongrel dogs had a 3 x 3 cm polytetrafluoroethylene (PTFE) aneurysm sewn as an interposition graft of the infrarenal aorta. A pressure transducer implanted into the aneurysm wall permitted continuous electronic IAP monitoring. Four aneurysms were excluded with a transluminally placed endovascular graft made of a PTFE graft and two Palmaz stents (PTFE-EG), three were excluded with a tantalum-Dacron endovascular graft (TD-EG), and one was surgically treated with a standard PTFE graft (PTFE-Surg). The dogs were observed for 18 to 50 days (mean, 37.5 days) and were evaluated after surgery with duplex and spiral computed tomographic scans. RESULTS: All grafts successfully excluded the aneurysms without perigraft channels or leaks as documented by arteriogram and duplex and computed tomographic scans. The mean IAPs after repair with all PTFE-EGs were significantly lower (p < 0.001) than the mean systemic pressures. In addition, the mean IAP reduction was significantly greater (p < 0.005) in the PTFE-EG group than in the TD-EG group. CONCLUSIONS: Aneurysm exclusion with PTFE-EG significantly lowered IAP, did so significantly better than the TD-EG, and approached the IAP reduction obtained by standard repair. Such pressure reduction is necessary for effective protection against aneurysm rupture.

Animals↗
PubMed1997

An experimental model for the acute and chronic evaluation of intra-aneurysmal pressure.

PURPOSE: To develop an animal model for the acute and chronic monitoring of pressure within abdominal aortic aneurysms (AAAs) to be treated with endovascular grafts. METHODS: A strain-gauge pressure transducer was placed within an AAA created from a prosthetic vascular graft. Prosthetic aneurysms were implanted into 17 canine infrarenal aortas. The intra-aneurysmal pressure was monitored and correlated with noninvasive forelimb sphygmomanometry for 2 weeks. After this time, an intravascular manometer catheter was passed into the aneurysm. Simultaneous pressure measurements were obtained using the implanted strain-gauge pressure transducer, the manometer catheter, and the forelimb sphygmomanometer. Angiography was performed to assess intraluminal morphology, aneurysm anastomoses, and adjoining aortic vessels. In addition, two control animals underwent intra-aneurysmal pressure monitoring after standard surgical aneurysm repair. RESULTS: There was excellent correlation (r = 0.97) between the pressure measurements obtained with the implanted strain-gauge pressure transducer and the intravascular manometer. Close correlation was also observed between the implanted strain-gauge transducer and the forelimb sphygmomanometer (r = 0.88) during postprocedural monitoring. Intra-aneurysmal pressure was lowered dramatically by surgical exclusion (aneurysm: 15/5 +/- 7/4 mmHg; systemic: 124/66 +/- 34/17 mmHg; p < 0.001). The prosthetic aneurysms were successfully imaged with angiography. CONCLUSIONS: This animal model provides an accurate and reproducible means for measuring intra-aneurysmal pressure on an acute and chronic basis. It may be possible to use this model in the assessment of endovascular devices to determine their efficacy in reducing intra-aneurysmal pressure. Evaluation of complications associated with their use, such as patent aneurysm side branches, perigraft channels, and perianastomotic reflux, may also be possible.

Animals↗
PubMed1996

Fluoroscopically assisted thromboembolectomy: an improved method for treating acute arterial occlusions.

We performed bilateral femoral artery dissections in a single 50 kg mongrel dog. Digital fluoroscopic arteriograms documented the luminal diameter of the left iliac and right superficial femoral arteries. Balloon thrombectomy catheter passage was performed through hemostatic sheaths by 12 surgeons. Embolectomy balloons were filled with radiographic contrast material and the balloon catheter diameter was compared with the underlying vessel diameter. The percentage of overdistention of the embolectomy balloon relative to the arterial wall was 23% +/- 5% in the iliac artery and 40% +/- 13% in the femoral artery. Over a 25-month period, we used fluoroscopically assisted thromboembolectomy to treat 21 patients with acute arterial or graft occlusions. As the balloon was gently withdrawn to extract intravascular thrombus, deformities of the compliant balloon profile caused by underlying arterial lesions were identified fluoroscopically and their locations recorded to facilitate further treatment. After initial clot removal in these 21 patients, 15 residual lesions were documented. Repeat thrombectomy (n = 8), balloon angioplasty (n = 3), and placement of intravascular stents (n = 4) eliminated all 15 lesions. Luminal continuity was successfully restored in all 21 of these patients, 10 of whom required distal open vascular reconstruction to correct existing outflow artery disease. Fluoroscopically assisted thromboembolectomy is a simple and safe method for treating acute arterial or graft occlusions in patients with diffuse arteriosclerosis. It minimizes arterial damage and blood loss during balloon thrombectomy and reduces the need for intravascular contrast agents. It also has the potential to facilitate accurate identification, localization, and treatment of significant underlying arterial lesions.

Adult↗
PubMed1996

Comparison of endovascular and conventional vascular prostheses in an experimental infection model.

INTRODUCTION: The causes and management of prosthetic graft infections have been extensively studied for conventional bypass grafts; however, the infectivity and therapy for endovascular graft infections are completely unknown. The aim of this study was to compare the biologic properties of infected aortic grafts when inserted by endoluminal or standard transabdominal techniques. METHODS: Eighteen dogs underwent placement of polytetrafluoroethylene grafts in their infrarenal aortas either by an endovascular technique (8) or a standard interposition technique (10). Endovascular grafts were constructed from polytetrafluoroethylene (3 cm) and two balloon-expandable stents coaxially mounted onto a balloon catheter delivery system. The grafts were inserted through a left carotid arteriotomy under fluoroscopic control. Initially, seven grafts were infected with decreasing inocula of Staphylococcus aureus, starting at 10(7) organisms per ml for 30 minutes and then rinsed briefly (10 seconds) in normal saline solution, until a 50% infective dose for the standard grafts was determined to be 10(2) organisms per ml. After this initial experiment, a second group of 11 dogs were compared at a concentration of 10(2) S. aureus per ml. Five dogs underwent endovascular repair, and six dogs had standard graft interpositions after an identical period of bacterial exposure. All grafts were removed at 2 weeks under sterile conditions and were submitted for quantitative culture analysis. RESULTS: Three of the six dogs (50%) with standard grafts appeared to clear their infections, whereas only one of the five dogs (20%) with an endovascular graft was free of organisms at 14 days. This results was further manifested by statistically significant lower postmortem colony counts in the standard grafts (p < 0.01). CONCLUSIONS: The endoluminal position of the graft and its proximity to the arterial wall do not appear to provide protection against infection. These data suggest that if endovascular grafts become infected, they may be in a disadvantaged position for host defense mechanisms to be effective.

Animals↗
PubMed1996

Immunolocalization and temporal distribution of cytokine expression during the development of vein graft intimal hyperplasia in an experimental model.

PURPOSE: Vein graft stenosis caused by intimal hyperplasia (IH) accounts for 30% to 50% of late bypass graft failures; however, the biochemical mediators of vein graft IH have been poorly defined. We attempted to evaluate the spatial and temporal distribution of five principal cytokines (interleukin-1 beta [IL-1 beta], platelet-derived growth factor-AA [PDGF-AA], basic fibroblast growth factor [bFGF], interferon gamma [INF gamma], and tumor necrosis factor alpha [TNF-alpha]) during the development of IH in a rat vein graft model. METHODS: Rat epigastric vein interposition grafts in the femoral artery were harvested at 6 hours, 2 days, 1 week, 2 weeks, and 4 weeks after the grafting procedure and studied with immunohistochemical and standard histologic techniques. The cytokine expression in the endothelium and media/neointima was quantified as the percentage of immunopositive cells per high-power field. RESULTS: Maximal hyperplasia occurred 2 weeks after the grafting procedure. Peak expression of IL-1 beta and bFGF occurred by 2 days. PDGF-AA expression paralleled the development of IH, peaking at 2 weeks and then declining. TNF-alpha expression increased at 1 week and remained elevated. INF gamma was seen only in control grafts. CONCLUSIONS: The coordinated early release of IL-1 beta and bFGF and the down-regulation of INF gamma seem to trigger an inflammatory response, thereby initiating IH. The process then is propagated by the release of PDGF-AA and TNF-alpha, with concomitant smooth muscle cell proliferation and production of extracellular matrix. It is likely that this complex milieu of local paracrine signaling is required to generate the hyperplastic response seen in failing vein grafts.

Actins↗
PubMed1996

Polytetrafluoroethylene bypasses to infrapopliteal arteries without cuffs or patches: a better option than amputation in patients without autologous vein.

PURPOSE: This study was undertaken to evaluate our results of polytetrafluoroethylene (PTFE) tibial and peroneal artery bypasses done for limb salvage. METHODS: Within a group of patients undergoing infrainguinal limb salvage bypasses at our institution between January 1986 and May 1995, 63 patients faced an immediate amputation, had no autologous vein on duplex examination and operative exploration, and had only a tibial or peroneal artery as an outflow vessel for bypass. Most of these patients (82%) had two or more prior ipsilateral infrainguinal bypasses. These 63 patients underwent 66 PTFE bypasses to a tibial or peroneal artery without a distal anastomotic vein cuff or an adjunctive arteriovenous fistula. Our results were then compared with those reported from infrapopliteal (crural) bypasses performed with alternate autologous vein sources or PTFE in conjunction with various recommended adjuncts. RESULTS: The 3- and 5-year cumulative primary graft patency rates for our PTFE infrapopliteal bypasses were 39%+/-7% and 28%+/-9%, respectively. Secondary graft patency rates were 55%+/-8% and 43%+/-10% at 3 and 5 years, respectively. Limb salvage rates were 71%+/-7% at 3 years and 66%+/-8% at 5 years. Two-year actuarial patient survival rate was only 67%+/-7%. CONCLUSIONS: These results indicate that a PTFE bypass to an infrapopliteal artery remains a worthwhile option in patients without usable autologous vein. The secondary patency and limb salvage rates were acceptable in this setting and were not significantly different from the best results reported with prosthetic tibial/peroneal bypasses with distal vein cuffs or patches (74% at 1 year; 58% at 3 years), arteriovenous fistulas (71% at 1 year) or composite arm vein grafts (39% and 29% at 3 and 5 years, respectively).

Actuarial Analysis↗
PubMed1996

Mediastinoscopy for the evaluation and treatment of projectile injuries.

This case report describes the first use of mediastinoscopy for the evaluation of a projectile injury and concomitant removal of the projectile. The described treatment made it possible to avoid the significant morbidity associated with mediansternotomy or thoracotomy. Complications secondary to retained mediastinal foreign bodies including infection, migration, and perforation were also avoided.

Adult↗