Biomedical subjects

Mark C Wyers

Publications and source records attributed to Mark C Wyers.

9 recordsLinked to original sources

PubMed2006

Shifting Wallgraft position: case reports and review of the forces affecting Wallgraft positioning.

Extensive use of stent-grafts in the iliac arteries is an increasingly common endovascular alternative to an aortobifemoral bypass procedure. The treatment of diffuse bilateral disease is frequently performed by using the technique of paired stent-grafts in the proximal common iliac arteries to effectively re-create the aortic-bifurcation. We present three patients treated with this technique who returned with recurrent occlusive disease. During subsequent treatment, the stent-grafts were noted to be in different positions from where they were initially deployed. A discussion of the possible explanations for the shifting positions follows.

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PubMed2005

Outcomes of renal artery angioplasty and stenting using low-profile systems.

OBJECTIVE: Renal artery percutaneous transluminal angioplasty (RPTA) and stenting (RAS) are accepted therapies for selected patients with renovascular hypertension and chronic renal insufficiency. We evaluated the outcomes and complications of RAS performed by vascular surgeons at our institution with modern low-profile systems. METHOD: We retrospectively analyzed all RPTA and RAS procedures attempted with the use of low-profile systems from June 2000 to September 2003. Eighty-two patients (96 arteries) with atherosclerotic renal artery stenosis were treated. Indication for treatment was hypertension in 44 (54%) and chronic renal insufficiency in 38 (46%). Technical success, complication rates, clinical success for control of hypertension or renal insufficiency, restenosis, and survival were reviewed with a mean follow-up of 1 year. RESULTS: Ninety-three arteries were treated with stents, three with RPTA only. Primary technical success was 95%, with 98% overall technical success. Major complications occurred in 6.1% and minor complications in 1.2%. Hypertension was improved in 81% at 1 year. Renal function was improved in 23%, stable in 53%, and worse in 24% at 1 year. Restenosis was seen by routine duplex surveillance in 25% at 1 year. Restenosis associated with clinical deterioration and confirmed by angiogram was seen in 10%. The overall 3-year survival was 83%. CONCLUSION: RPTA/RAS can be performed with low-profile systems with excellent technical success, low complication rates, and clinical outcomes that compare favorably with prior reports.

Angioplasty, Balloon↗

PubMed2005

Restenosis in gold-coated renal artery stents.

BACKGROUND: Gold coating improves stent visibility under fluoroscopy. This is particularly valuable for precise stent placement during renal artery stenting (RAS). There is conflicting evidence regarding restenosis with gold-coated stents. To evaluate the effect of gold coating on restenosis after renal stenting, we reviewed the results of all patients undergoing RAS in our practice. METHODS: A retrospective cohort study of all patients undergoing RAS between June 2000 and September 2003 was performed. During this time, both gold-coated and stainless steel stents were used. Restenosis (>60% diameter) was determined by serial follow-up duplex exams (peak systolic velocity >180 cm/s and renal-aortic ratio >3.5). Restenosis rates were determined by using the Kaplan-Meier life-table method. Variables potentially affecting restenosis were evaluated with the log-rank test and Cox proportional hazards modeling. RESULTS: RAS was performed in 97 arteries (78 patients). Gold-coated (NIRoyal) stents were placed in 59 arteries (48 patients). Stainless steel stents (Corinthian, Genesis, and Herculink) were placed in 38 arteries (34 patients). Patient demographics, indication for treatment, technical success, and complications did not differ between gold and stainless steel stent groups. Mean follow-up was 15 months for gold-coated stents and 18 months for stainless steel stents (NS). By life-table method, 1-year and 2-year freedom from restenosis rates were 84% and 78% in arteries treated with stainless steel stents versus 69% and 39% in those treated with gold-coated stents (P = .012, log-rank test). By multivariate analysis, only the use of gold-coated stents (P = .018; hazard ratio [HR], 3.3; 95% confidence interval [CI], 1.2 to 8.7) and bilateral disease (P = .046; HR, 2.3; 95% CI, 1.02 to 5.2) predicted restenosis. Stent diameter, patient demographics, and indication for RAS had no effect on restenosis by univariate analysis. According to American Heart Association criteria, 87% of patients in the stainless steel group had improved blood pressure at 1 year, compared with 77% in the gold-coated stent group (Kaplan-Meier; P = .042, log-rank test). There were no significant differences in the effect of RAS on serum creatinine levels between the two groups. CONCLUSION: Gold-coated renal stents had a substantially higher rate of restenosis than stainless steel stents in our series. These findings have led us to abandon the use of gold-coated stents for RAS. Patients who have received gold-coated stents for the treatment of atherosclerotic renal artery stenosis should be followed closely for evidence of restenosis.

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PubMed2005

Mesenteric stenting for chronic mesenteric ischemia.

BACKGROUND: Mesenteric stenting has not been widely adopted for the treatment of chronic mesenteric ischemia (CMI). The recent availability of embolic protection and low-profile devices with the theoretical ability to decrease perioperative bowel necrosis, led us to begin using mesenteric stenting for patients with CMI. We review our initial experience to examine short-term outcomes. METHODS: We performed a retrospective analysis of all patients who were treated by vascular surgeons with mesenteric stenting for CMI. Patients with acute mesenteric ischemia were excluded. We evaluated perioperative morbidity and mortality, restenosis, recurrent symptoms, and reintervention. Kaplan-Meier methods were used to assess events during follow-up. We also compared these outcomes with a historical control group of patients treated with open surgical revascularization. RESULTS: Fourteen patients underwent mesenteric stenting over the past 3 years. Mean age was 73, and 64% were women. There was no perioperative or 30-day mortality or major morbidity. Early restenosis and recurrent symptoms occurred in 10% and 9% of patients at 6 months. At a mean follow-up of 13 months, 53% of patients underwent reintervention. However, 93% were symptom-free at their last follow-up. Compared with open surgery, stent patients had lower perioperative major morbidity (30% vs 0%, P < .01) and shorter hospital and intensive care unit length of stay (median 10 days vs 2 days, and 3 days vs 0 days, respectively, P < .01 for both). However, stent patients were seven times as likely to develop restenosis (P < .01), four times more likely to develop recurrent symptoms (P < .01), and 15 times more likely to undergo reintervention (P < .01). There was one death 13 months after stenting due to mesenteric infarction in a patient lost to follow-up. One patient was successfully converted to open surgery after a second restenosis. He had regained 20 pounds and was determined to be a better operative candidate than at his initial presentation. There was no perioperative or 30-day mortality or major morbidity with reintervention after mesenteric stenting. CONCLUSION: Mesenteric stenting for CMI can be performed with low perioperative risk. However, stenting is associated with early restenosis and recurrent symptoms requiring secondary procedures. Patients with severe nutritional depletion or high surgical risk may benefit from mesenteric stenting for CMI, but close follow-up is required. Later open surgery can be performed for restenosis if nutritional status and surgical risk are improved, or repeat angioplasty and stenting can be effectively performed if operative risk remains high.

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PubMed2004

Management of carotid injuries in a hostile neck using endovascular grafts.

Pseudoaneurysms and iatrogenic injuries of the extracranial carotid artery are not common but represent unique operative challenges with associated high morbidity and mortality. We report two cases in which a Wallgraft was used via percutaneous femoral access to treat such injuries. In the first, a 6-cm carotid pseudoaneurysm was successfully excluded by coil embolization of the external carotid artery and stent grafting across the carotid bifurcation. In the second case, an endovascular graft was used to treat an intraoperative common carotid injury in a re-operated, radiated neck. These cases demonstrate the utility of endovascular graft treatment of emergent carotid injuries.

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PubMed2003

Endovascular repair of abdominal aortic aneurysm without preoperative arteriography.

OBJECTIVE: Clinical trials of endovascular aortic aneurysm repair (EVAR) have required both preoperative aortography and computed tomography (CT). We codeveloped specialized three-dimensional (3-D) reconstruction and computer-aided measurement, planning, and simulation software (3-D CAMPS) based on CT or magnetic resonance imaging, to eliminate the need for preoperative arteriography. METHODS: EVAR with 3-D CAMPS as the sole preoperative imaging method was performed in 196 patients from 1996 to 2001, with six endograft types in three configurations. Physical examination, abdominal radiography, and CT (3D-CAMPS) were performed at 1, 6, and 12 months, then annually. RESULTS: For a subset of cases in which a comparison could be made, 3-D CAMPS was superior to angiography for prediction of endograft length and iliac access. Hospital mortality was zero, and 30-day mortality was 0.5%. In three patients immediate conversion to open repair (1.5%) was necessary because of previously unknown stent-graft mechanical limits. Incidence of endoleak was 15% at 1 month, 10% at 6 months, 6% at 12 months, and 7% at 24 months, and 92% of endoleaks were type II. Mean follow-up was 18 months. Aneurysm-related mortality was zero. Nineteen secondary procedures (all endovascular) were performed in 16 patients (8%). For all graft types, freedom from secondary procedure was 94% at 1 year and 90% at 2 years, and this was better for endografts ultimately approved by the US Food and Drug Administration (96% at 1 year, 95% at 2 years; P =.02). No known measurement-related complications occurred in the series. Results for secondary intervention and endoleak compare favorably to series with similar endograft types. CONCLUSIONS: EVAR can be performed with 3-D CAMPS as the sole preoperative imaging method to achieve outcomes comparable to the best series published for each endograft type. CT with 3-D CAMPS can effectively eliminate the need for preoperative arteriography and avert associated morbidity, expense, and exposure to contrast agent and radiation.

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PubMed2003

Abdominal aortic aneurysm size regression after endovascular repair is endograft dependent.

OBJECTIVE: This study was performed to determine whether abdominal aortic aneurysm (AAA) regression is different with various endografts after endovascular repair. METHODS: A four-center retrospective review of size change after endovascular AAA repair was performed. Consecutive patients with at least 1-year follow-up and available imaging studies were included. Three hundred ninety patients received either the Ancure, AneuRx, Excluder, or Talent endograft. AAA size and endoleak status were recorded from computed tomography (CT) scans at the initial postoperative follow-up visit and at 1 and 2 years thereafter. AAA size was defined as the minor axis of the infrarenal aorta on the largest axial section on the two-dimensional CT scan. A change in AAA size of 0.5 cm or greater from baseline was considered clinically significant. The effect of initial size, endoleak, and type of endograft on AAA regression was analyzed. RESULTS: Mean baseline size was significantly greater with Talent endografts and smaller with Excluder endografts. Clinically significant regression in AAA size occurred in nearly three fourths of patients with Ancure and Talent endografts at 2 years. Regression in AAA size was less frequent with the AneuRx (46%) and Excluder (44%) devices. Initial size, endoleak, and endograft type were significant predictors of regression at multivariate analysis at 1 year. However, by 2 years only endograft type was still an independent predictor of AAA shrinkage. CONCLUSIONS: Long-term morphologic changes after endovascular aneurysm repair depend on endograft type.

Aortic Aneurysm, Abdominal↗

PubMed2002

Vascular smooth muscle cells derived from atherosclerotic human arteries exhibit greater adhesion, migration, and proliferation than venous cells.

BACKGROUND: Phenotypic variation of vascular smooth muscle cells (VSMC) may result in altered biological behavior and responses. Within the vessel wall, arterial VSMC have a greater propensity to form atherosclerotic lesions as compared to venous VSMC. In this study the rates of proliferation, adhesion, and migration were compared between VSMC of atherosclerotic arterial and venous origin. MATERIALS AND METHODS: Human VSMC cultures were isolated from 18 infragenicular arteries at the time of below knee amputation and from 20 saphenous veins during lower extremity revascularization surgery. Cell cultures were isolated from the media of each specimen and maintained in distinct cell lines for all assays. Cells from passages 2 and 3 were assayed for their proliferative capacity using total DNA fluorescence photometry and for adhesion and migration using a modified Boyden chamber. RESULTS: Patient age and the incidence of atherosclerotic risk factors did not vary significantly between the arterial and the venous patient groups. VSMC of atherosclerotic arterial origin demonstrated greater proliferation (arterial, 162 +/- 59 absorption units, vs. venous, 106 +/- 56 absorption units, P < 0.001), adhesion (arterial, 74.1 +/- 22.6 cells/microscopic field, vs. venous, 41.3 +/- 12.8 cells/microscopic field, P < 0.001) and migration (arterial, 427 +/- 185 cells/microscopic field, vs venous, 119 +/- 101 cells/microscopic field, P < 0.001) than VSMC of venous origin. CONCLUSION: Human atherosclerotic arterial VSMC exhibit significantly increased rates of proliferation, adhesion, and migration as compared to human venous VSMC. These observations of VSMC in culture are consistent with the clinical predilection for the hyperplasic responses that result in the development of atherosclerosis in the arterial wall. Possible intrinsic differences in VSMC phenotype should be considered in designing methods to limit atherosclerosis.

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PubMed2002

Internal iliac occlusion without coil embolization during endovascular abdominal aortic aneurysm repair.

PURPOSE: When abdominal aortic aneurysms and common iliac artery (CIA) aneurysms undergo concomitant endovascular repair, endograft limb extension into the external iliac artery is often necessary. Usually, the internal iliac artery (IIA) is coil embolized in such a case to prevent endoleak. It has been our practice to coil embolize the IIA only in cases where there is not adequate stent graft seal in the CIA immediately proximal to the IIA origin (effectively sealing the entire IIA origin). In this study, we evaluated the outcomes of this approach. METHODS: We retrospectively reviewed 204 consecutive endovascular abdominal aortic aneurysm repairs at Dartmouth-Hitchcock Medical Center from 1996 to 2001. Computed tomographic angiography with three-dimensional reconstruction was the primary preoperative imaging modality, and the decision to cover the IIA without concomitant coil embolization was based before surgery on the presence of adequate graft oversizing (> or =10% to 15%) in the most distal 5 mm of CIA and 15 mm of proximal external iliac artery, respectively. RESULTS: The IIA was occluded 33 times in 31 patients. In 22 cases (67%), the IIA was covered without coil embolization (COVER group). The remaining 11 patients (33%) with inadequate graft oversizing in the CIA underwent IIA coil embolization (COIL group). The follow-up periods for the COVER and COIL groups were 19 +/- 2 months and 10 +/- 3 months, respectively. All operations in both groups were technically successful without evidence of endoleak at completion angiography. No endoleaks, graft migrations, or aneurysm enlargements were associated with the covered or coiled IIAs during the follow-up period. No clinical sequelae were seen in the COVER group, with the exception of buttock claudication in six patients (27%) that resolved completely in five patients. In the COIL group, five patients (45%) had buttock claudication. In addition, one case of buttock necrosis and one case of ischemic neuropathy occurred in the COIL group. CONCLUSION: Covering the IIA without coiling effectively excluded the CIA aneurysm in every case and was associated with a low incidence rate of complications compared with coil embolization. With detailed preoperative imaging and patient selection, IIA coil embolization may not be necessary in as many as two thirds of patients who need IIA occlusion.

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