Biomedical subjects

Stephen T Kee

Publications and source records attributed to Stephen T Kee.

26 records · Page 2Linked to original sources

PubMed2002

Temporary IVC filtration before patent foramen ovale closure in a patient with paradoxic embolism.

Pulmonary embolism (PE) and associated acute peripheral ischemia suggest the diagnosis of paradoxic embolism. The most common intracardiac defect associated with paradoxic emboli is a patent foramen ovale (PFO). Therapeutic options include anticoagulation, thrombolysis, inferior vena cava (IVC) filtration, and closure of the intracardiac defect. The authors discuss the diagnosis and treatment of a young female athlete who presented with massive PE complicated by a paradoxic embolus to the right subclavian artery. Systemic and catheter-directed thrombolysis, IVC filtration, and percutaneous closure of a PFO were performed in an effort to return the patient to the level of competitiveness she desired.

Adolescent↗

PubMed2002

Noninvasive measurement of extraction fraction and single-kidney glomerular filtration rate with MR imaging in swine with surgically created renal arterial stenoses.

PURPOSE: To test whether magnetic resonance (MR) imaging enables accurate measurement of extraction fraction (EF) in swine with unilateral renal ischemia and to evaluate effects of renal arterial stenosis on EF and single-kidney glomerular filtration rate. MATERIALS AND METHODS: High-grade unilateral renal arterial stenoses were surgically created in eight pigs. Direct measurements of renal venous and arterial inulin concentration provided reference standard estimates of single-kidney EF. Pigs were imaged with a 1.5-T imager to estimate EF, renal blood flow, and glomerular filtration rate. A breath-hold inversion-recovery spiral sequence was used to measure T1 of blood in the infrarenal inferior vena cava and renal veins after intravenous administration of gadopentetate dimeglumine, and these data were used to calculate EF. Cine-phase contrast material-enhanced imaging of the renal arteries provided quantitative renal blood flow measurements. Bilateral single-kidney glomerular filtration rate was then determined: glomerular filtration rate = renal blood flow x (1 - hematocrit level) x EF. RESULTS: A statistically significant linear correlation was found between EF, as determined with MR imaging, and inulin (r = 0.77). As compared with kidneys without renal arterial stenosis, kidneys with renal arterial stenosis showed 50% (0.14/0.28) EF reduction (P <.01) and 59% glomerular filtration rate reduction (P <.01). CONCLUSION: MR imaging shows promise for in vivo measurement of EF and glomerular filtration rate, which may be useful in assessing the clinical importance of renal arterial stenosis.

Animals↗

PubMed2002

Interventional musculoskeletal procedures performed by using MR imaging guidance with a vertically open MR unit: assessment of techniques and applicability.

PURPOSE: To evaluate the safety of and time required for a broad range of musculoskeletal interventional procedures performed by using magnetic resonance (MR) imaging guidance with a vertically open 0.5-T unit. MATERIALS AND METHODS: Sixty-three MR imaging-guided procedures were performed. A vertically open MR unit equipped with in-room display monitors allowed interactive freehand MR guidance predominantly with fast spin-echo and gradient-echo sequences. Each procedure was classified in terms of the anatomic location, procedure type, and tissue type involved. The procedures were evaluated for success of needle placement, adequacy of tissue sampling, total procedural time, needle time, number of needle passes, and complications. RESULTS: Procedures consisted of tissue sampling with core-needle (n = 6) or fine-needle aspiration (n = 20) biopsy, corticosteroid or contrast agent injection (n = 19), joint cyst aspiration (n = 7), and drainage (n = 11). Successful needle placement was achieved in all 63 cases. Cytologic and histologic tissue samples were sufficient for pathologic diagnosis in 24 of 26 cases. In two cases, complications occurred: transient local bleeding and a brief vasovagal episode. The mean total procedural time was 64.8 minutes; the mean needle time, 26.2 minutes; and the mean number of needle passes per patient, 1.6. CONCLUSION: With use of a vertically open MR unit, MR-guided interventional procedures involving bone, soft tissue, intervertebral disks, and joints are safe and sufficiently rapid for use in clinical practice.

Adult↗

PubMed2002

Angiographic classification of ovarian artery-to-uterine artery anastomoses: initial observations in uterine fibroid embolization.

PURPOSE: To prospectively study and classify the anastomoses between the ovarian and uterine arteries in women undergoing uterine fibroid embolization, and to compare the presence of such with procedural failures and premature menopause. MATERIALS AND METHODS: Angiographic ovarian artery-to-uterine artery anastomoses were studied in 76 consecutive patients undergoing uterine fibroid embolization. Mean patient age was 44.7 years (range, 29-56 years). Clinical follow-up consisted of a standard questionnaire. Procedural failure and complications were compared with the presence of various types of ovarian artery-to-uterine artery connections. RESULTS: Three types of anastomoses were identified. In type I (33 [21.7%] of 152 arteries), flow from the ovarian artery to the uterus was through anastomoses with the main uterine artery. In type II (six arteries [3.9%]), the ovarian artery supplied the fibroids directly. In type III (10 arteries [6.6%]), the major blood supply to the ovary was from the uterine artery. Seven patients (9%) were considered to have clinical failure, with three of the six women with type II anastomoses being in this group. Three of the five women who experienced menopause after fibroid embolization had bilateral ovarian artery-to-uterine artery anastomoses that were classified as high risk. CONCLUSION: Delineation of ovarian artery-to-uterine artery anastomosis is of practical relevance in avoiding nontarget ovarian embolization, in identification of those who would be at risk of uterine artery embolization or ovarian failure, and in those in whom the ovarian artery can be embolized safely.

Adult↗

PubMed2002

Initial clinical results of tenecteplase (TNK) in catheter-directed thrombolytic therapy.

PURPOSE: To investigate the safety and immediate efficacy of 2 different doses of tenecteplase (TNK) in peripheral catheter-directed thrombolytic therapy of arterial occlusions and deep vein thrombosis (DVT). METHODS: Over a 20-month period, 63 nonconsecutive patients underwent catheter-directed thrombolytic therapy with either 0.25 mg/h or 0.50 mg/h of TNK in a nonrandomized, open-label study. Of these, 55 patients (60 limbs) were treated for DVT (36 limbs in 16 men and 15 women; mean age 41 years, range 21-73) or peripheral arterial occlusions (24 limbs in 16 men and 8 women; mean age 63 years, range 32-91). The primary endpoints were major bleeding complications and angiographic reduction in clot burden. RESULTS: The mean duration of infusion was 18 +/- 4 hours in patients with arterial occlusions and 30 +/- 13 in those with DVT. Twenty-one (87.5%) patients with occlusive disease had marked or complete lysis of clot. Thirty (83.3%) limbs with DVT had either marked or complete resolution of thrombus. There were 4 (7.3%) episodes of minor bleeding with 1 (1.8%) major hemorrhagic event. Fibrinogen levels dropped by an average of 23%. CONCLUSIONS: Preliminary evidence suggests that TNK doses of 0.25 mg/h to 0.50 mg/h appear to be safe and effective. The potential benefits of TNK therapy warrant further investigation.

Adult↗

PubMedDate not supplied

Thoracic aortic stent-grafting.

The surgical management of thoracic disease has improved steadily over the past 20 years due to advances in diagnostic and surgical techniques. Despite this progress, a less invasive approach to treatment is desirable. Patients with coexisting cardiovascular or pulmonary diseases may not tolerate aortic replacement under general anesthesia, particularly combined with extracorporeal bypass. Endovascularly placed stent-grafts offer an alternative therapy, which is less invasive and associated with a shorter hospital recuperation time than with traditional operative therapy. The authors discuss the development of stent-grafts for use in the thoracic aorta, along with the various techniques utilized during these complex procedures.

Aortic Dissection↗

PubMedDate not supplied

Pulmonary radiofrequency ablation--an international study survey.

BACKGROUND: The lung is the most common site for primary cancer worldwide as well as being a common site of metastases for various malignancies. Percutaneous radiofrequency ablation (RFA) is rapidly evolving as a new minimally invasive tool for the treatment of pulmonary tumors. PATIENTS AND METHODS: A questionnaire was sent by e-mail to 14 centres around the world, which we knew or thought were performing percutaneous pulmonary RFA, to retrospectively survey their experience in this field including the number of ablations done to date, indications, method, peri- and postprocedural complications. RESULTS: Seven centers reported 493 percutaneous procedures in lung tumors. Two deaths have been reported. Complications were subdivided into major and minor complications. Pneumothorax occurred in up to 30% of interventions with less than 10% requiring intercostal drainage. Pleural effusion requiring aspiration occurred in less than 10% of cases. CONCLUSION: With almost 500 procedures done to date, percutaneous pulmonary RFA appears to be a safe, minimally invasive tool for local pulmonary tumor control with negligible mortality, little morbidity, short hospital stay and gain in quality of life.

Catheter Ablation↗

PubMedDate not supplied

Portal vein thrombosis after laparoscopic splenectomy: an ongoing clinical challenge.

OBJECTIVES: Portal vein thrombosis (PVT) following open splenectomy is a potentially lethal complication with an incidence of up to 6%. The objective of this report is to describe our management of a recent laparoscopic case, discuss current therapies, and consider antiplatelet therapy for prophylaxis. METHODS: Medical records, laboratory studies, and imaging studies pertaining to a recent case of a laparoscopic splenectomy were examined. Current literature related to this topic was reviewed. RESULTS: A 16-year-old girl underwent laparoscopic splenectomy for idiopathic thrombocytopenic purpura. Her preoperative platelet count was 96K. She was discharged on postoperative day 1 after an uneventful operation including division of the splenic hilum with an endoscopic linear stapler. On postoperative day 20, she presented with a 5-day history of epigastric pain, nausea, and low-grade fevers without peritoneal signs. Her white blood cell count was 17.3; her platelets were 476K. Computed tomography demonstrated thrombosis of the splenic, superior mesenteric, and portal veins propagating into the liver. Heparinization was begun followed by an unsuccessful attempt at pharmacologic and mechanical thrombolysis by interventional radiology. Over the next 5 days, her pain resolved, she tolerated a full diet, was converted to oral anticoagulation and sent home. Follow-up radiographic studies demonstrated the development of venous collaterals and cavernous transformation of the portal vein. DISCUSSION: No standard therapy for PVT exists; several approaches have been described. These include systemic anticoagulation, systemic or regional medical thrombolysis, mechanical thrombolysis, and surgical thrombectomy. Unanswered questions exist about the most effective acute therapy, duration of anticoagulation, and the potential efficacy of routine prophylaxis with perioperative antiplatelet agents. PVT following splenectomy occurs with both the open and laparoscopic approach.

Adolescent↗