Biomedical subjects

L A Sanchez

Publications and source records attributed to L A Sanchez.

At least 37 records · Page 2Linked to original sources

PubMed1998

Percutaneous transluminal angioplasty for the treatment of limb threatening ischemia: do the results justify an attempt before bypass grafting?

PURPOSE: Results of percutaneous transluminal angioplasty (PTA) in selected cases have been reported to be equal or superior to those of arterial bypass graft surgery, with a lower morbidity and mortality. We performed PTA of stenotic or occlusive lesions in patients with limb-threatening ischemia, hoping to improve our overall success and decrease morbidity in this group of patients. The results of PTA in the limb-salvage setting was evaluated. METHODS: From 1992 to 1995, 307 PTAs were performed in 257 patients. One hundred sixty-one (63%) patients had diabetes mellitus, and 32 (12%) patients had renal failure. All patients were evaluated by means of pulse volume recordings and ankle brachial indices at 1 and 6 weeks after PTA and at 3 month intervals thereafter. Seventeen patients (9%) were lost to follow-up. The continued success or failure of PTA was defined by means of noninvasive vascular laboratory criteria, patency by means of pulse examination, the need for subsequent bypass grafting across the index lesion, and limb salvage. RESULTS: The 1-year patency rates for external iliac PTAs (56%) were significantly lower (P <.05) than those for common iliac PTAs (87%). Infrainguinal PTAs at the femoral, popliteal, and tibial level had 1-year patency rates of less than 15%. CONCLUSION: Common iliac artery PTA is justified in most cases in which it is feasible. However, when PTAs are performed below the inguinal ligament, the results are markedly worse. One-year patency rates of PTA in this group of patients with threatened limbs are inferior to the patency rates of arterial bypass grafts, even when these bypasses are performed with a prosthetic material. PTA should not be considered as a primary treatment modality for patients with infrainguinal arterial occlusive disease who also have limb-threatening ischemia, except in unusual circumstances.

Aged↗

PubMed1998

Endoleaks after endovascular graft treatment of aortic aneurysms: classification, risk factors, and outcome.

PURPOSE: Incomplete endovascular graft exclusion of an abdominal aortic aneurysm results in an endoleak. To better understand the pathogenesis, significance, and fate of endoleaks, we analyzed our experience with endovascular aneurysm repair. METHODS: Between November 1992 and May 1997, 47 aneurysms were treated. In a phase I study, patients received either an endovascular aortoaortic graft (11) or an aortoiliac, femorofemoral graft (8). In phase II, procedures and grafts were modified to include aortofemoral, femorofemoral grafts (28) that were inserted with juxtarenal proximal stents, sutured endovascular distal anastomoses within the femoral artery, and hypogastric artery coil embolization. Endoleaks were detected by arteriogram, computed tomographic scan, or duplex ultrasound. Classification systems to describe anatomic, chronologic, and physiologic endoleak features were developed, and aortic characteristics were correlated with endoleak incidence. RESULTS: Endoleaks were discovered in 11 phase I patients (58%) and only six phase II patients (21%; p < 0.05). Aneurysm neck lengths 2 cm or less increased the incidence of endoleaks (p < 0.05). Although not significant, aneurysms with patent side branches or severe neck calcification had a higher rate of endoleaks than those without these features (47% vs 29% and 57% vs 33%, respectively), and patients with iliac artery occlusive disease had a lower rate of endoleaks than those without occlusive disease (18% vs 42%). Endoleak classifications revealed that most endoleaks were immediate, without outflow, and persistent (71% each), proximal (59%), and had aortic inflow (88%). One patient with a persistent endoleak had aneurysm rupture and died. CONCLUSIONS: Endoleaks complicate a significant number of endovascular abdominal aortic aneurysm repairs and may permit aneurysm growth and rupture. The type of graft used, the technique of graft insertion, and aortic anatomic features all affect the rate of endoleaks. Anatomic, chronologic, and physiologic classifications can facilitate endoleak reporting and improve understanding of their pathogenesis, significance, and fate.

Aged↗

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

Technique for obtaining proximal intraluminal control when arteries are inaccessible or unclampable because of disease or calcification.

When proximal arterial control cannot be obtained by standard methods, it may be achieved safely and bloodlessly by intraluminal routes with balloon catheters, hemostatic sheaths, and catheter-guide wire techniques. This method was used successfully in 20 patients to achieve proximal arterial control without complications in a variety of locations. Use of this method or its modifications may facilitate and simplify a variety of vascular operations that would otherwise be difficult or hazardous.

Angioplasty, Balloon↗

PubMed1998

Accuracy of duplex ultrasound in evaluating carotid artery anatomy before endarterectomy.

PURPOSE: Anatomic features, such as a high carotid bifurcation (< 1.5 cm from the angle of the mandible), excessive distal extent of plaque (> 2.0 cm above the carotid bifurcation), or a small diameter (< or = 0.5 cm) redundant or kinked internal carotid artery can complicate carotid endarterectomy. In the past, arteriography was the only preoperative study capable of imaging these features. This study assessed the ability of duplex ultrasound to evaluate their presence before surgery. METHODS: A consecutive series of 20 patients who underwent 21 carotid endarterectomies had preoperative duplex ultrasound evaluations of these anatomic features. These evaluations were correlated with operative measurements from an observer blinded to the duplex findings. RESULTS: The mean difference between duplex and operative measurements for the distance between the carotid bifurcation and the angle of the mandible, the distal extent of plaque, and the internal carotid artery diameter was 0.9 cm, 0.3 cm, and 0.8 mm, respectively. The correlation coefficient between the two methods was 0.86, 0.75, and 0.59, respectively. Duplex ultrasound predicted a high carotid bifurcation, excessive distal extent of plaque, or a redundant or kinked internal carotid artery with 100% sensitivity (p < 0.05, p < 0.01, and p < 0.001, respectively). The sensitivity of duplex ultrasound in predicting a small internal carotid artery diameter was 80%. The specificity of duplex ultrasound for predicting excessive distal extent of plaque, small internal carotid artery diameter, high carotid bifurcation, and a coiled or kinked carotid artery was 92%, 56%, 100%, and 100%, respectively. CONCLUSION: Duplex ultrasound can predict the presence of anatomic features that may complicate carotid endarterectomy. Preoperative duplex imaging of these features may be helpful in patients who undergo carotid endarterectomy without preoperative arteriography.

Aged↗

PubMed1998

Diagnosis and treatment of chronic lower extremity ischemia.

Chronic lower extremity ischemia is due to progressive atherosclerosis of the aorto-iliac and/or infrainguinal arteries. This disease process is of great importance as millions of patients are affected by lower extremity arterial occlusive disease. Most of these patients are asymptomatic but a growing number of them are symptomatic, with complaints ranging from mild claudication to gangrene. The increasing number of patients affected by lower extremity atherosclerosis is, in part, due to the 'graying' of the general population and to the medical improvements of the past three decades that have allowed patients with generalized atherosclerosis to survive longer. Fortunately, the diagnosis and management of peripheral arterial occlusive disease has also significantly progressed leading to improved graft patency, limb salvage rates, and quality of life for patients.

Aorta↗

PubMed1998

Value of CT angiography for postoperative assessment of patients with iliac artery aneurysms who have received endovascular grafts.

OBJECTIVE: The purpose of the study was to assess the usefulness of CT angiography for follow-up of patients with iliac artery aneurysms who have undergone endovascular treatment. SUBJECTS AND METHODS: Twelve patients with iliac artery aneurysms (10 true aneurysms and two pseudoaneurysms) were examined with CT angiography within 1 week of receiving transfemorally placed endovascular grafts. All patients underwent follow-up CT angiography from 3 to 30 months (mean, 11 months) later. Follow-up CT angiography at 6 months or later (mean, 14 months) was also available in 10 patients. All studies were obtained after i.v. contrast administration using 3-mm collimation, 1.6-2.0 pitch, 2-mm retrospective reconstruction, and with subsequent three-dimensional rendering and multiplanar reformation. The shape and patency of the graft, perigraft thrombosis, and the size of the aneurysm were assessed. RESULTS: All grafts remained patent and without deformity. Complete thrombosis of the aneurysm was shown by initial postoperative CT angiography in 11 patients and confirmed by follow-up studies. A single case of a perigraft leak was revealed by CT angiography and confirmed by follow-up angiography. No aneurysm showed change in size at late follow-up. CONCLUSION: CT angiography is an accurate method for evaluating endovascular devices. CT angiography can be used as a primary technique for follow-up of patients who have undergone endovascular repair of iliac aneurysms.

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PubMed1998

Endovascular therapy for upper extremity injury.

Various endovascular techniques, including the placement of embolization coils, intravascular stents, and the use of stented grafts, have been used in the setting of traumatic upper extremity injuries. Coil embolization and stent placement are effective in a limited number of cases. Endovascular grafts have greatly extended the potential of endovascular therapy for upper extremity vascular trauma. The ideal graft material, stent, and the best mechanism for stent deployment have not been determined. In addition, long-term effectiveness of such therapy is yet to be shown. Nevertheless, endovascular grafts offer distinctive advantages in some cases and are important tools for the treatment of vascular trauma and should be included in the armamentarium of all vascular surgeons.

Angioplasty, Balloon↗

PubMed1997

Anastomotic intimal hyperplasia: a comparison between conventional and endovascular stent graft techniques.

Endovascular grafts (EVGs) have been proposed as a treatment for a variety of vascular diseases; however, the impact of EVGs on graft healing has not been fully evaluated. The aim of this study is to compare anastomotic intimal hyperplasia (AIH) and endothelialization in EVGs and conventional bypass grafts (CGs). Seven mongrel dogs received an EVG in one iliac artery and a CG in the other iliac artery using a 5 mm x 4 cm polytetrafluoroethylene graft. The EVG was secured to the native vessel wall, with balloon expandable stents at either ends of the graft. CGs were anastomosed using running sutures. Intravascular ultrasound was performed at the time of sacrifice (8 weeks) to determine percentage of stenosis at the distal anastomosis. Specimens were divided longitudinally for light microscopic analysis (thickness of distal AIH) and scanning electron microscopic studies (percentage of endothelial coverage of the graft). Percentage of stenosis at the distal anastomosis was significantly higher in EVGs compared with CGs (28.2 +/- 18.2% versus 1.8 +/- 2.8%; P < 0.01) due to significantly greater mean intimal thickness in the EVGs (441.1 +/- 101.1 microns versus 82.4 +/- 41.9 microns; P < 0.01). The total percentage of area covered by endothelial cells was also significantly greater in EVGs compared with CGs (80.5 +/- 37.5% versus 30.3 +/- 37.1%; P < 0.05). Intraluminal location enhanced endothelialization of the polytetrafluoroethylene graft; however, it also resulted in greater AIH. Further device refinements including stent design may be required to maximize the potential of these endovascular procedures.

Anastomosis, Surgical↗

PubMed1997

Sudden neonatal death in carnitine transporter deficiency.

A newborn infant died suddenly and unexpectedly on day 5 of life. Postmortem investigations led to a suspicion of carnitine transporter deficiency, a diagnosis supported by the finding that both parents are heterozygotes for this disorder. The fasting stress caused by poor breast-feeding with no formula supplements and, possibly, the vegetarian diet of the mother were likely the critical factors leading to neonatal death, an outcome previously not described in this disorder.

Adipose Tissue↗

PubMed1997

Endovascular grafts for noninfected aortoiliac anastomotic aneurysms.

PURPOSE: This report describes our experience with endovascular repair of aortic and iliac anastomotic aneurysms. METHODS: Between June 1994 and March 1996, 12 noninfected aortic or iliac anastomotic aneurysms in 10 patients who had serious comorbid medical conditions that precluded or made difficult standard operative repair were treated using endovascular grafts. No patient in this study had a history of fever, leukocytosis, or computed tomographic evidence of a periprosthetic fluid collection that was suggestive of infection of the original graft. Endovascular grafts composed of polytetrafluoroethylene and balloon-expandable stents were introduced through a femoral arteriotomy and were placed using over-the-wire techniques under C-arm fluoroscopic guidance. RESULTS: Endovascular grafts were successfully inserted in all patients with aortic or iliac anastomotic aneurysms. There were no procedure-related deaths, and complications included one postprocedure wound hematoma and one perioperative myocardial infarction. Graft patency has been maintained for a mean of 16.1 months, with no computed tomographic evidence of aneurysmal enlargement or perigraft leakage. CONCLUSIONS: Endovascular grafts appear to be a safe and effective technique for excluding some noninfected aortoiliac anastomotic aneurysms in high-risk patients and may become a treatment option in all patients who have clinically significant lesions.

Aged↗

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↗

PubMed1997

Should vascular surgeons perform endovascular procedures and how can they acquire the skills to do so?

Endovascular treatment techniques have already replaced some vascular operations. The likelihood is that new endovascular techniques involving stents and stented grafts will replace additional vascular operations. All of these treatments involve the use of catheter-guidewire, balloon, and imaging modalities, particularly digital fluoroscopy. These modalities have already and will increasingly help to improve and simplify standard vascular operations such as thromboembolectomy, infrainguinal bypasses, and management of aneurysms and arteriovenous fistulas. Accordingly, vascular surgeons must become familiar with and use these endovascular methods and techniques. This can be accomplished in a variety of ways, including working as part of a multidisciplinary vascular treatment group in which various specialists collaborate to provide the best, most cost-effective care to vascular disease patients.

Angioplasty, Balloon↗

PubMed1997

Varying strategies and devices for endovascular repair of abdominal aortic aneurysms.

The endovascular repair of abdominal aortic aneurysms has been investigated in a clinical setting since 1991. Although initially the procedure was performed using surgeon-made devices, it did not take long for the medical industry to realize the potential of this procedure. There are six commercially made devices, which are unique, each with their own strengths and weaknesses. This article describes the principal endovascular graft types that are currently under investigation as well as the strategies for their use. In addition, the inclusion criteria for endovascular repair of abdominal aortic aneurysms are discussed.

Aortic Aneurysm, Abdominal↗

PubMed1997

Endovascular approaches for traumatic arterial lesions.

Vascular injuries caused by blunt or penetrating trauma can be challenging to diagnose and treat, particularly when they involve central vessels. Endovascular treatment for vascular trauma includes the placement of embolization coils and intravascular stents and the employment of stented grafts. The use of stented grafts appears to be associated with decreased blood loss, a less invasive insertion procedure, reduced requirements for anesthesia, and a limited need for an extensive dissection in a traumatized field. These advantages are especially important in patients with central arteriovenous fistulas or false aneurysms, particularly those who are critically ill from other coexisting injuries or medical comorbidities. In these circumstances, the use of stented grafts already appears justified to treat traumatic central arterial lesions. Endovascular grafts are important tools for the treatment of vascular trauma, and they should be included in the armamentarium of the vascular surgeon.

Angiography↗

PubMed1997

Endovascular grafting for aortoiliac occlusive disease.

Aortoiliac occlusive disease is a significant cause of lower extremity ischemic symptoms. Over the past two decades, most patients have been treated with a variety of surgical procedures, including aortofemoral and extra-anatomic bypasses. Most recently, percutaneous balloon angioplasty and stents have been successfully used for the treatment of limited iliac lesions. New endovascular grafts that combine vascular grafts with stents in a device with new characteristics may allow the successful treatment of patients with extensive aortoiliac occlusive disease in a less invasive fashion. In our early experience, the endovascular grafts were constructed with Palmaz balloon-expandable stents and standard polytetrafluoroethylene (PTFE) grafts. The 18-month primary and secondary patency rates were 89% and 100%, respectively, with a limb salvage rate of 94%. Endovascular grafts can be successfully used to treat patients with extensive aortoiliac occlusive disease, with excellent early results. Long-term results and further graft improvements will define their role in the treatment of patients with aortoiliac occlusive disease.

Aorta, Abdominal↗