Publications by authors named "Sam Ahn"

Objective: Brachiocephalic vein (BCV) obstruction can cause dialysis access dysfunction and failure. Central vein stenosis involving the BCV may require advanced endovascular procedures. We report that most BCV occlusions can be treated using simple endovascular techniques on an outpatient basis.

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Background: Superior vena cava (SVC) occlusion in dialysis patients is a serious complication that can cause SVC syndrome and vascular access dysfunction. While endovascular therapy has advanced to become the first line of treatment, open surgical treatment may still be needed occasionally. However, no long term outcome data has been previously reported.

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The health care system in Peru treats 15,000 dialysis patients annually. Approximately 45% of patients receive therapy using catheters. The incidence of catheter-induced superior vena cava (SVC) occlusion is increasing along with its associated significant morbidity and vascular access dysfunction.

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Background: Subclavian vein and brachiocephalic vein occlusions are challenging problems in dialysis patients with ipsilateral upper extremity (UE) vascular access or in need of one. HeRO grafts (Hemodialysis Reliable Outflow, Merit Medical Systems, Inc, South Jordan, UT) have been used to manage such occlusions but patients with chronic hypotension treated with HeRO graft may have threatened patency. We describe an alternative technique using a supraclavicular stent graft to reconstruct the venous outflow, evaluate outcomes of this procedure, and discuss its role in complex hemodialysis patients.

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Objective: Thoracic central vein (TCV) obstruction (TCVO) in the presence of upper extremity (UE) hemodialysis access can present as superior vena cava syndrome (SVCS) and cause vascular access dysfunction and failure. We report the techniques and results of endorevascularization of TCVO in hemodialysis patients, which allowed for long-term functioning vascular access in the UE.

Methods: From June 2009 to February 2020, 45 hemodialysis patients underwent TCV endorevascularization.

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Objective: The radial artery is often used for coronary angiography, with a demonstrated decrease in local complications and an increase in postoperative mobility of the patient. Data on radial artery access for peripheral endovascular procedures, however, are limited. We describe our experience with radial artery access for diagnostic and endovascular interventions.

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Common variable immune deficiency is a heterogeneous immune deficiency characterized by reduced serum immunoglobulins and a lack of antibodies. As the name implies, B-cell defects are variably defective. In particular, peripheral blood isotype-switched CD27(+) memory B cells are reduced in number and have been the basis of several classification schemes.

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CD4+-lymphocyte counts (LCs) play a crucial role in the management and monitoring of HIV infection. Variability in CD4+ LCs has been reported to occur as a result of measurement techniques and/or biological variations. We report on the CD4+ LCs of healthy human immunodeficiency virus (HIV)-seronegative adults in Botswana.

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Extracranial internal carotid artery (ICA) mycotic aneurysms are rare entities that may result in significant neurologic morbidity and mortality. Several operative techniques have been described in the literature for the management of this difficult condition. This case report describes a contained ruptured mycotic aneurysm of the extracranial ICA associated with Proteus mirabilis infection successfully treated by an end-to-end spatulated interposition saphenous vein graft.

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