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Biomedical subjects

Eugene S Lee

Publications and source records attributed to Eugene S Lee.

7 recordsLinked to original sources
PubMed2007

Vascular surgery: an update.

Caring for patients with vascular illnesses has become increasingly more complex and has changed dramatically over the past 10 years, with a widening array of diagnostic and treatment options. Carotid artery stenting has the potential to become a viable alternative to open surgery in high-risk patients with carotid artery disease (i.e., patients older than 80 years and those with previous neck surgery or irradiation, contralateral carotid artery occlusion, contralateral laryngeal nerve injury, or angina). However, the effectiveness of carotid artery stenting as a therapy is still being evaluated in randomized trials. Endovascular aortic aneurysm repair is an option for patients who desire or require a less invasive modality and who have suitable aortic anatomy. Surgical reconstruction remains the standard treatment for ischemic rest pain and tissue loss (critical limb ischemia). Balloon angioplasty and stenting are treatment options for peripheral vascular disease, although treatment is dependent on the arterial segment or segments involved.

Aortic Aneurysm, Abdominal↗
PubMed2007

Training with simulation improves residents' endovascular procedure skills.

BACKGROUND: Endovascular procedure simulators are now commercially available and in use for physician training. The purpose of this study was to evaluate the role of simulation-based training in vascular surgery residencies. METHODS: Residents from vascular surgery programs in a five-state area were invited to participate in a series of 2-day endovascular training programs that used a high-fidelity endovascular procedure simulator (SimSuite; Medical Simulation Corporation, Denver, Colo), didactic instruction, computer-based training, and tabletop procedure demonstrations. The curriculum covered arteriography and intervention for treatment of aortoiliac, renal, and carotid artery disease. Nine residents participated, with one to three per training session. Each completed an average of 9.5 simulated endovascular cases. Performance on a standardized TransAtlantic Inter-Society Consensus B iliac angioplasty/stenting case was used to assess endovascular skills and knowledge at the beginning of the training program, and this was repeated at the completion of the training. Performance metrics were measured by the simulator, faculty observed trainees' performance of simulated cases, and trainees provided their evaluations of the usefulness of the simulation experiences. RESULTS: Endovascular procedural skills on the standardized iliac intervention case improved after completion of the training program. Compared with performance early on day 1, performance improved (P < or = .05; paired t test): total procedure time decreased 54%, volume of contrast decreased 44%, and fluoroscopy time decreased 48% (mean change from baseline). Selection of angioplasty balloon catheters and stents was improved, and the average number of catheters used and stents deployed decreased, although this did not reach statistical significance. Faculty observation allowed identification of shortcomings of knowledge and skills, including common problems with selection of catheter, balloon, and stent sizes; correct positioning of the sheath; and intraprocedural monitoring. Postcourse evaluations indicated support for the use of simulation in vascular surgery residents' endovascular training. CONCLUSIONS: Training with a simulator, incorporated into an individual or small group learning session, offers a means to learn and realistically practice endovascular procedures without direct risk to patients, with measurable improvements in key performance metrics. How simulation training affects subsequent clinical performance has yet to be established.

Endoscopy↗
PubMed2006

Intraoperative colon mucosal oxygen saturation during aortic surgery.

BACKGROUND: Colonic ischemia after aortic reconstruction is a devastating complication with high mortality rates. This study evaluates whether Colon Mucosal Oxygen Saturation (CMOS) correlates with colon ischemia during aortic surgery. MATERIALS AND METHODS: Aortic reconstruction was performed in 25 patients, using a spectrophotometer probe that was inserted in each patient's rectum before the surgical procedure. Continuous CMOS, buccal mucosal oxygen saturation, systemic mean arterial pressure, heart rate, pulse oximetry, and pivotal intra-operative events were collected. RESULTS: Endovascular aneurysm repair (EVAR) was performed in 20 and open repair in 5 patients with a mean age of 75 +/- 10 (+/-SE) years. CMOS reliably decreased in EVAR from a baseline of 56% +/- 8% to 26 +/- 17% (P < 0.0001) during infrarenal aortic balloon occlusion and femoral arterial sheath placement. CMOS similarly decreased during open repair from 56% +/- 9% to 15 +/- 19% (P < 0.0001) when the infrarenal aorta and iliac arteries were clamped. When aortic circulation was restored in both EVAR and open surgery, CMOS returned to baseline values 56.5 +/- 10% (P = 0.81). Mean recovery time in CMOS after an aortic intervention was 6.4 +/- 3.3 min. Simultaneous buccal mucosal oxygen saturation was stable (82% +/- 6%) during aortic manipulation but would fall significantly during active bleeding. There were no device related CMOS measurement complications. CONCLUSIONS: Intra-operative CMOS is a sensitive measure of colon ischemia where intraoperative events correlated well with changes in mucosal oxygen saturation. Transient changes demonstrate no problem. However, persistently low CMOS suggests colon ischemia, thus providing an opportunity to revascularize the inferior mesenteric artery or hypogastric arteries to prevent colon infarction.

Aged↗
PubMed2005

Moderate hyperoxia (40%) increases antioxidant levels in mouse tissue.

BACKGROUND: Oxygen is routinely administered to patients to improve clinical outcome. Since studies have shown that administering 100% oxygen can cause unwanted side effects, intermediate concentrations of 40% oxygen are used in clinical practice. In this study, we examined whether the breathing of 40% oxygen causes beneficial effects upon tissue levels of antioxidants such as vitamin E, vitamin C, and glutathione. METHODS: Four-month-old mice were separated into two groups: control (n = 11) and experimental (n = 11). The treatment group was administered 40% oxygen for 10 days. Brain, heart, lung, liver, testes, and skeletal muscle were harvested and tissue antioxidant levels were determined by HPLC. RESULTS: Vitamin E concentrations were higher in brain, heart, lung, liver, and testes of the treatment group (P < 0.05). Glutathione concentrations were higher in the lung tissue only (P < 0.05). No differences were found in vitamin C levels. CONCLUSIONS: The data suggest that mice respond to oxidative stress by increasing tissue vitamin E incorporation and cellular synthesis of glutathione in the lung when exposed to moderate levels (40%) of hyperoxia.

Animals↗
PubMed2005

Iliac fixation length and resistance to in-vivo stent-graft displacement.

PURPOSE: Migration of endovascular stent grafts has been related to the security of proximal device fixation to the aortic neck. This study evaluated the importance of iliac fixation in preventing longitudinal in vivo device displacement of a modular, externally supported stent graft. METHODS: Experimental ovine infrarenal aneurysms (n = 8) were treated with a fully supported, modular, bifurcated stent graft (AneuRx, Medtronic, Santa Rosa, Calif). Minimum iliac fixation length (1 cm) was used in four animals and iliac extender modules were used to achieve maximum iliac fixation in four animals. Suture anastomosis of bifurcated polyester grafts to the infrarenal aorta served as controls (n = 8). Aortic grafts were displaced in vivo by applying downward traction to a guidewire that was passed over the iliac flow divider and brought out both femoral arteries. The displacement force needed to initiate stent-graft migration was recorded and compared with the force needed to disrupt the sutured anastomosis. RESULTS: There was no difference in animal weight (88.8 +/- 2.5 kg vs 87.5 +/- 2.9 kg), aortic neck diameter (12.7 +/- 0.9 mm vs 13.4 +/- 1.1 mm), aortic neck length (23.2 +/- 0.9 mm vs 21.8 +/- 2.4 mm), experimental aneurysm size (24.7 +/- 1.1 mm vs 24.2 +/- 2.0 mm), or iliac artery diameter (9.0 +/- 1.5 mm vs 9.3 +/- 0.5 mm) among the groups. Iliac fixation length was 31.0 +/- 0.3 mm in the maximum iliac fixation group and 11 +/- 0.25 mm in the minimum fixation group (P < .0001). Peak displacement force to initiate migration was 30.2 +/- 5.5 N (range, 25 to 38) in animals with maximum iliac fixation compared with 18.1 +/- 3.7 N (range, 13 to 21) in those with minimum fixation (P = .01). The force needed to disrupt the control surgical anastomosis was 40.6 +/- 7.5 N (range, 31 to 50) (P < .01). CONCLUSIONS: Maximizing iliac fixation length increases the longitudinal in vivo force needed to displace a fully supported stent graft by 67%. This suggests that increasing iliac fixation length may reduce the long-term risk of migration in patients undergoing endovascular aneurysm repair.

Anastomosis, Surgical↗
PubMed2002

Supplemental oxygen reduces intimal hyperplasia after intraarterial stenting in the rabbit.

HYPOTHESIS: Supplemental oxygen can reduce intimal hyperplasia (IH) after stent deployment in a rabbit model. BACKGROUND: Endovascular stent placement is technically feasible, but long-term durability in vessels outside the aortoiliac system is compromised with postinterventional IH, which causes restenosis and failure of the arterial conduit. METHODS: Groups (n = 4 to 6) of female New Zealand white rabbits underwent placement of a 3-mm intraaortic stent with laparotomy and were placed in either normoxic (21% inspired oxygen concentration) or supplemental-oxygen (40% inspired oxygen concentration) environments for 0, 7, 14, and 28 days. The transarterial wall oxygen gradient was measured at 0, 7, and 28 days with an oxygen microelectrode. 5-Bromo-2'deoxyuridine (BrdU) was injected into the peritoneum before death to assess cellular proliferation. Aortic specimens were harvested en bloc and sectioned for analysis of cellular proliferation and intimal thickness. RESULTS: Intraaortic stent placement significantly decreased the transarterial wall oxygen gradient in the outer 70% of the vessel wall and was easily reversed at 7, 14, and 28 days with application of supplemental oxygen. Cellular proliferation was significantly decreased at 14 days (0.5% +/- 0.001% versus 2.3% +/- 0.002%; P <.001) and 28 days (0.4% +/- 0.001% versus 1.0% +/- 0.001%; P <.025) as measured with count of nuclei staining for 5-Bromo-2'deoxyuridine in the intima and media. Intimal thickness was significantly decreased at 28 days in oxygen-supplemented rabbits (intimal area/medial area = 0.50 +/- 0.07) as compared with controls (intimal area/medial area = 0.89 +/- 0.11; P <.025). CONCLUSION: This study shows the ability of supplemental oxygen to reverse arterial wall hypoxia, decrease cellular proliferation, and control IH at the deployment site of an intraarterial stent in a rabbit model. Forty-percent supplemental oxygen suppresses IH by 44% at 28 days as compared with normoxic control values. Cellular proliferation is reduced four-fold at 14 days and two-fold at 28 days in oxygen-supplemented rabbits as compared with control media after deployment. The clinical implications of these findings are significant, especially as the role of endovascular interventions continues to expand.

Animals↗