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Biomedical subjects

Steven S Kang

Publications and source records attributed to Steven S Kang.

5 recordsLinked to original sources
PubMed2005

Study of the venous reflux progression.

BACKGROUND: Patients with chronic venous disease (CVD) often ask whether elective vein surgery could be delayed without consequences. Because the natural history of CVD is not well known, this study was designed to determine its progression in such patients. METHODS: One hundred and sixteen limbs in 90 patients who had at least 2 exams with duplex ultrasound (DU) scanning prior to vein surgery at a university medical center were studied. These were patients who were offered an operation but for various reasons were treated at a later stage. Patients were classified by the CEAP system. RESULTS: The mean age of the patients was 49 years (range, 23 to 81 years). A second DU scan was performed 1 to 43 months after the initial exam (median, 19 months). Eighty-five limbs (73.3%) were unchanged. Thirteen limbs (11.2%) had progression of clinical stage, and seven had progression on DU scanning as well. Seven limbs progressed from C2 to C3, four limbs from C3 to C4, and two limbs from C4 to C6. Thirty-four limbs had a documented change on repeat DU scanning. In 3 of these limbs, reflux was missed on the initial exam; therefore, 31 limbs had progression of disease. The great saphenous vein and tributaries were the most often anatomic sites affected by a change, followed by perforators. Seventeen limbs (14.7%) had extension of pre-existing reflux, and 14 (12.1%) had reflux in a new segment. In 11 of these limbs, a change in the initial plan for treatment was required. Symptomatic or DU changes were noted 6 months or later in 95% of limbs and 74.2% of limbs with disease progression were diagnosed at 12 months or later. All but one of the 13 symptomatic limbs developed symptoms at least a year later. CONCLUSION: Nearly one third of patients with venous reflux had progression. Anatomic extension is frequent with disease progression but not a pre-requisite. Progression was found in most limbs 6 months after the initial study. Patients undergoing treatment for their veins may need another DU exam if this time interval is exceeded.

Adult↗
PubMed2005

Hemodynamic effects of intermittent pneumatic compression in patients with critical limb ischemia.

BACKGROUND: Traditional teaching assumes that the distal arterial tree is maximally dilated in patients with critical limb ischemia (CLI). Endovascular or arterial bypass procedures are the commonly used interventions to increase distal perfusion. However, other forms of treatment such as spinal cord stimulation or intermittent pneumatic compression (IPC) have been shown to improve limb salvage rates. This prospective study was designed to determine if the use of IPC increases popliteal, gastrocnemial, collateral arterial, and skin blood flow in patients with CLI. METHODS: Twenty limbs with CLI in 20 patients (mean age, 74 years) were evaluated with duplex ultrasound scans and laser Doppler fluxmetry in the semi-erect position before, during, and after IPC. One pneumatic cuff was applied on the foot and the other on the calf. The maximum inflation pressure was 120 mm Hg and was applied for 3 seconds at three cycles per minute. All patients had at least two-level disease by arteriography. Fourteen limbs were characterized as inoperable, and six were considered marginal for reconstruction. Flow volumes were measured in the popliteal, medial gastrocnemial, and a genicular collateral artery. Skin blood flux was measured on the dorsum of the foot at the same time. RESULTS: Significant flow increase during the application of IPC was found in all three arteries (18/20 limbs) compared with baseline values (P < .02). The highest change was seen in the popliteal, followed by the gastrocnemial and the collateral artery. After the cessation of IPC, the flow returned to baseline. This was attributed to the elevation of time average velocity, as the diameter of the arteries remained unchanged. The skin blood flux increased significantly as well (P < .03). In the two limbs without an increase in the arterial or skin blood flow, significant popliteal vein reflux was found. Both limbs were amputated shortly after. CONCLUSIONS: IPC increases axial, muscular, collateral, and skin blood flow in patients with CLI and may be beneficial to those who are not candidates for revascularization. Patients with significant venous reflux may not benefit from IPC. This supports the theory that one of the mechanisms by which IPC enhances flow is by increasing the arteriovenous pressure gradient.

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PubMed2004

Predictors of early discharge following open abdominal aortic aneurysm repair.

Patients undergoing endovascular abdominal aortic aneurysm (AAA) repair have lower perioperative morbidity and leave the hospital earlier than patients undergoing open repair. However, potential complications require continuous surveillance of endografts and there are few data regarding their long-term fate. If an open operation were well tolerated, this might be a preferable alternative. The purpose of this study was to identify patients with lower morbidity and shorter hospital stay following open AAA repair and to analyze factors that might point to open repair as the preferred approach. We performed a retrospective review of all patients who underwent AAA repair between 1995 and 2000 at our institution. All patients with ruptured aneurysms and those that required renal, celiac, or superior mesenteric reconstructions during the AAA repair were excluded. Patient demographics, preoperative comorbid conditions, intraoperative data, and postoperative complications were analyzed in detail. A total of 115 patients fulfilled the inclusion criteria. There was only one perioperative death (0.9%). The mean hospital stay was 8.1 days. A history of chronic obstructive pulmonary disease (COPD) and longer operative time were independent factors associated with prolonged hospital stay. Forty-one patients (35.6%) left the hospital in 5 or less days. Compared to the group with hospital stay >5 days, these patients had a lower incidence of COPD (7.3% vs. 25.7%, p < 0.05) and smaller-size AAAs (5.6 vs. 6.4 cm, p < 0.0001), and were more often operated on via a retroperitoneal approach (61% vs. 40.5%, p < 0.05). Their time in the operating room was less (3.5 vs. 4.5 hr, p < 0.0001), and they had less estimated blood loss (750 vs. 1500 cc, p < 0.001) and fewer transfusions (0.95 vs. 2.45 units, p < 0.0001). Patients without COPD and smaller AAAs that can be repaired via a retroperitoneal approach have a lower incidence of perioperative complications and a shorter hospital stay following open AAA repair. Until long-term results for endografts are available, our data suggest that these patients are well served with an open repair.

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PubMed2003

Definition of venous reflux in lower-extremity veins.

PURPOSE: This prospective study was designed to determine the upper limits of normal for duration and maximum velocity of retrograde flow (RF) in lower extremity veins. METHODS: Eighty limbs in 40 healthy subjects and 60 limbs in 45 patients with chronic venous disease were examined with duplex scanning in the standing and supine positions. Each limb was assessed for reflux at 16 venous sites, including the common femoral, deep femoral, and proximal and distal femoral veins; proximal and distal popliteal veins; gastrocnemial vein; anterior and posterior tibial veins; peroneal vein; greater saphenous vein, at the saphenofemoral junction, thigh, upper calf, and lower calf; and lesser saphenous vein, at the saphenopopliteal junction and mid-calf. Perforator veins along the course of these veins were also assessed. In the healthy volunteers, 1553 vein segments were assessed, including 480 superficial vein segments, 800 deep vein segments, and 273 perforator vein segments; and in the patients, 1272 vein segments were assessed, including 360 superficial vein segments, 600 deep vein segments, and 312 perforator vein segments. Detection and measurement of reflux were performed at duplex scanning. Standard pneumatic cuff compression pressure was used to elicit reflux. Duration of RF and peak vein velocity were measured immediately after release of compression. RESULTS: Duration of RF in the superficial veins ranged from 0 to 2400 ms (mean, 210 ms), and was less than 500 ms in 96.7% of these veins. In the perforator veins, regardless of location, outward flow ranged from 0 to 760 ms (mean, 170 ms), and was less than 350 ms in 97% of these veins. In the deep veins, RF ranged from 0 to 2600 ms. Mean RF in the deep femoral veins and calf veins was 190 ms, and was less than 500 ms in 97.6% of these veins. In the femoropopliteal veins, mean RF was 390 ms, and ranged from 510 to 2600 ms in 21 of 400 segments; however, RF was less than 990 ms in 99% of these veins. Duration of RF was significantly longer in all three veins systems in patients (P <.0001 for all comparisons). With a cutoff value of more than 1000 ms rather than more than 500 ms, prevalence of abnormal RF in the femoropopliteal veins was significantly reduced, from 29% to 18% (P =.002). Thirty-seven vein segments (2.4%) had RF greater than 500 ms in the supine position, compared with less than 500 ms in 22 of these vein segments (59%) in the standing position. Of the 48 vein segments (3.1%) with RF greater than 500 ms in the standing position, RF was less than 500 ms in 6 of these vein segments (13%) in the supine position. Similar observations were noted in patient veins. There was no association between RF and peak vein velocity. Peak vein velocity had no significance in determining reflux. CONCLUSIONS: The cutoff value for reflux in the superficial and deep calf veins is greater than 500 ms. However, the reflux cutoff value for the femoropopliteal veins should be greater than 1000 ms. Outward flow in the perforating veins should be considered abnormal at greater than 350 ms. Reflux testing should be performed with the patient standing.

Adult↗