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Biomedical subjects

E V Lang

Publications and source records attributed to E V Lang.

At least 19 recordsLinked to original sources
PubMed2001

Classifying complications of interventional procedures: a survey of practicing radiologists.

PURPOSE: To determine the variability of radiologists' classification of complications from interventional procedures. MATERIALS AND METHODS: Fifteen test cases were selected from a database of morbidity and mortality cases that occurred in our department during the past 2 years. Ten cases were selected randomly, and five were chosen because of classification difficulties within our department. A survey with the case descriptions was presented to 145 SCVIR members via the World Wide Web and 48 were distributed to participants at a statewide angiography club meeting. Participants were asked to complete a short assessment of the their clinical background and to classify each case as "no complication," "minor complication," or "major complication." RESULTS: Thirty-eight percent (74 of 193) of the surveys were completed. Seventy percent (52 of 74) of the respondents were affiliated with an academic program, 12% (nine of 74) were affiliated with private practice groups, and 18% (13 of 74) claimed both academic and private affiliation. The consensus rate in classifying the complications for the randomly selected cases varied from 50% to 95%, with a median of 69%, and the consensus rate in classifying the selected cases varied from 46% to 95%, with a median of 85%. The lowest consensus rates occurred when (i) a significant procedural event was followed by a normal outcome, (ii) when a procedure was aborted, and (iii) when a significant event occurred but did not prolong hospital stay. CONCLUSION: Current criteria for reporting complications are associated with moderate rates of disagreement among interventional radiologists.

Adult↗
PubMed2001

Impact of graft material configuration on stent-graft endoleak in vitro.

PURPOSE: To assess the effect of different attachment patterns between graft materials and stents on type I endoleak. MATERIALS AND METHODS: Nitinol stents were covered with a coating of Tegaderm in either a straight-edged pattern across the stent cells or a contoured zigzag pattern conforming to the stent skeleton's honeycomb-shaped cells. The stent-grafts were deployed in an ex vivo circuit across a gap of tubing to simulate an aneurysm cavity. Fluid leaking from the gap for more than 30 minutes was recorded as endoleak. Two contoured attachment patterns (short and long necks) and four straight-edged patterns with necks of varying length were tested. Each experiment was repeated 15 times. RESULTS: The length of the aneurysm neck covered by the graft material was inversely related to the rate of endoleak. The zigzag pattern of graft attachment demonstrated significantly less endoleak than the straight-edged pattern in the setting of a short aneurysm neck (0.25 mL vs 47.3 mL). CONCLUSION: Adopting the contoured (zigzag) attachment of graft material to stents minimizes endoleak in vitro, particularly in the setting of a short aneurysm neck.

Aortic Aneurysm, Abdominal↗
PubMed2001

Evaluation of a spiral nitinol temporary inferior vena caval filter.

RATIONALE AND OBJECTIVES: The authors performed this study to evaluate the (a) ability of a prototype temporary inferior vena caval (IVC) filter to trap and retain emboli in an ex vivo flow circuit, (b) feasibility of filter placement and removal via a superficial vein in sheep, and (c) intermediate-term effects of the filter on the insertion vein and at the filter site. MATERIALS AND METHODS: In an iliocaval circuit, embolus capture with the prototype filter was compared to that with a Greenfield filter. In addition, prototype filters were placed into the infrarenal IVC in six sheep. Placement via a superficial venous route was initially attempted. Inferior vena cavography was performed weekly, and filters were removed after 2, 3, or 4 weeks (n = 2 each). Two weeks after the filters were removed, vena cavograms were obtained, the animals were sacrificed, and the IVC was evaluated at pathologic examination. RESULTS: The prototype filter captured all emboli, and the Greenfield filter captured 70%-100% of emboli. Successful placement via a superficial venous route was accomplished in only two sheep owing to small vein caliber; four filters were placed via a deep vein. Adverse events included perifilter thrombus, insertion site infection, and caudal migration. Two sheep died before filter removal owing to sepsis and anesthetic complications. The filters in the remaining four sheep were easily and successfully removed. Five sheep had stenosis at the filter site, and fibrosis with acute and chronic inflammation was seen at microscopic examination. CONCLUSION: The prototype filter trapped emboli as well as the Greenfield filter. Insertion via a superficial route, however, is possible only if the access vein is of an adequate size.

Alloys↗
PubMed2001

Impact of unilateral common iliac vein occlusion on trapping efficacy of the Greenfield filter: an in vitro study.

RATIONALE AND OBJECTIVES: The purpose of this study was to assess the effect of unilateral common iliac vein occlusion on the capturing efficacy of the Greenfield filter in vitro. MATERIALS AND METHODS: A stainless steel over-the-wire Greenfield filter was placed in the Silastic inferior vena cava module of a pulsatile circuit. Three 30-mm blood clots in sets of five were injected through the module's right iliac limb with the circuit in four experimental conditions: vertical position, both iliac limbs patent (VP); vertical position, left iliac limb occluded (VOC); horizontal position, both iliac limbs patent (HP); and horizontal position, left iliac limb occluded (HOC). Each experiment was repeated 15 times, resulting in 75 clots per condition and a total of 300 clot introductions. RESULTS: Clot trapping efficacy was 36 of 75 (48%) for VP, 41 of 75 (55%) for VOC, 32 of 75 (43%) for HP, and 26 of 75 (35%) for HOC. Cross comparisons of the four conditions revealed a marginally significant difference (P = .0138 with a corrected test-wise alpha = .0125) only between horizontal and vertical positions with unilateral common iliac limb occlusion. CONCLUSION: Unilateral common iliac vein occlusion decreases the capturing efficacy of the Greenfield filter in the horizontal position in vitro. In patients with unilateral common iliac vein occlusion, use of inferior vena cava filters with higher capturing efficacy may be considered.

Dimethylpolysiloxanes↗
PubMed2001

Clinical competence assessment in radiology: introduction of an objective structured clinical examination in the medical school curriculum.

RATIONALE AND OBJECTIVES: Traditional oral and written examinations can be limited in predicting future clinical performance. Therefore Objective Structured Clinical Examinations (OSCEs) have been introduced in other specialties. The authors assessed their value in radiology. MATERIALS AND METHODS: The study includes 122 Harvard medical students who undertook 1-month compulsory clerkships at one of three hospitals (A, B, or C) in their 3rd and 4th year and a compulsory OSCE in their 4th year. The OSCE was constructed from five cases. Each had eight or nine standardized questions designed to test, within a set time, the perception of essential findings, their interpretation, and clinical judgment (maximum possible score, 100). Clerkship grades were high honors (score of 3), honors (score of 2), satisfactory (score of 1), and fail (score of 0). Predictors of OSCE scores-clerkship grade and affiliated hospital-were modeled as linear functions. Time elapsed between clerkship and OSCE was modeled as a nonlinear function. RESULTS: Although there was a positive relation between clerkship grade and OSCE grade, it accounted for an increase of only 5.7% in OSCE score per clerkship grade and did not predict performance of individual students. Students who trained in hospital B showed significantly higher OSCE grades. OSCE scores were highest when the examination was taken 8 months after the clerkship. CONCLUSION: The OSCE may be useful to uncover deficits in individuals and groups beyond the ones detected with traditional clerkship evaluations and provide guidance for remediation. The improved performance after additional clinical exposure suggests that the OSCE may be well suited to test the integration of radiologic and clinical knowledge.

Clinical Clerkship↗
PubMed2000

Adjunctive non-pharmacological analgesia for invasive medical procedures: a randomised trial.

BACKGROUND: Non-pharmacological behavioural adjuncts have been suggested as efficient safe means in reducing discomfort and adverse effects during medical procedures. We tested this assumption for patients undergoing percutaneous vascular and renal procedures in a prospective, randomised, single-centre study. METHODS: 241 patients were randomised to receive intraoperatively standard care (n=79), structured attention (n=80), or self-hypnotic relaxation (n=82). All had access to patient-controlled intravenous analgesia with fentanyl and midazolam. Patients rated their pain and anxiety on 0-10 scales before, every 15 min during and after the procedures. FINDINGS: Pain increased linearly with procedure time in the standard group (slope 0.09 in pain score/15 min, p<0.0001), and the attention group (slope 0.04/15 min; p=0.0425), but remained flat in the hypnosis group. Anxiety decreased over time in all three groups with slopes of -0.04 (standard), -0.07 (attention), and -0.11 (hypnosis). Drug use in the standard group (1.9 units) was significantly higher than in the attention and hypnosis groups (0.8 and 0.9 units, respectively). One hypnosis patient became haemodynamically unstable compared with ten attention patients (p=0.0041), and 12 standard patients (p=0.0009). Procedure times were significantly shorter in the hypnosis group (61 min) than in the standard group (78 min, p=0.0016) with procedure duration of the attention group in between (67 min). INTERPRETATION: Structured attention and self-hypnotic relaxation proved beneficial during invasive medical procedures. Hypnosis had more pronounced effects on pain and anxiety reduction, and is superior, in that it also improves haemodynamic stability.

Adult↗
PubMed2000

Rapid anxiety assessment in medical patients: evidence for the validity of verbal anxiety ratings.

Rapid assessment of patient anxiety is necessary to insure quality care. A number of self-report measures provide valid and reliable measures of anxiety. These measures can be time-consuming to complete, however, and may be burdensome to medical patients who are in pain or acute anxiety states. Many medical procedures are performed in conditions in which written measures are cumbersome (e.g. patient in supine position), and scoring and interpretation of written measures in a busy clinical setting may be difficult for medical personnel. The present study provides validity data for a verbally administered (0-10) anxiety rating. One hundred and ninety-eight adult interventional radiology patients completed standard measures assessing state anxiety, trait Negative and Positive Affect, and the dimensions of the five-factor model of personality. Verbal anxiety rating was highly correlated with Spielberger's State Anxiety Inventory, showed moderate correlations to the related constructs of neuroticism and trait Negative Affect, and was largely unrelated to theoretically distinct constructs. Verbal anxiety ratings made prior to the invasive procedure also predicted pain and anxiety during the procedure. The verbal anxiety rating also demonstrated sensitivity to changes in anxiety that occurred as a result of changes in situation. Findings support the convergent and discriminant validity of verbal anxiety ratings.

Adolescent↗
PubMed1999

Carbon dioxide angiography: effect of injection parameters on bolus configuration.

PURPOSE: Predict the intravascular distribution of carbon dioxide during angiography. MATERIALS AND METHODS: Mathematical modeling was used to predict the flow pattern of CO2 in a pulsatile system as a function of the CO2 flow rate. Findings were validated in an in vitro pulsatile circuit. RESULTS: The annular flow pattern with filling of nearly the entire lumen with CO2 is the most desirable, followed by intermittent bubble flow (provided individual bubbles are large). Stratified flow relates to a continuous floating CO2 bubble. Configuration of the CO2 bolus depends on fluid properties, fluid velocity, flow rates, mean intraluminal pressure, pressure amplitude, pulse rate, and vessel diameter. In vessels with less than 10-mm inner diameter, annular flow can be achieved relatively easily with injection rates above 20-30 mL/sec. Higher rates are not expected to produce superior results. When imaging a 2-cm artery, the best that can be realized clinically is intermittent flow with large bubbles. Bubbles size increases with increasing CO2 flow rate. In aneurysms, only stratified flow can be achieved with reasonable injection rates. Periodicity of the flow patterns is determined by the pulsatile circuit and can produce indentations in the CO2 bolus, which can be mistaken for stenoses. CONCLUSIONS: Flow regime maps can be used to optimize bolus configuration during CO2 angiography.

Algorithms↗
PubMed1999

Sharp recanalization of central venous occlusions.

PURPOSE: To describe a sharp puncture technique for recanalization of chronic central venous occlusions that could not be traversed by a guide wire. MATERIALS AND METHODS: Five patients presented with six longstanding central venous occlusions that could not be traversed with a guide wire after thrombolysis. The occlusions occurred following radiation for lung carcinoma (n = 2) and indwelling venous catheters (n = 4). The length of venous occlusion was determined by simultaneously advancing transbrachial and transfemoral catheters to the site of occlusion. Initially, a curved guiding catheter with a Rosch-Uchida needle and, in subsequent patients, a coaxial sheathed needle with a 21-gauge stylet were used for recanalization. The recanalized veins were then balloon dilated and stents were placed. RESULTS: With use of this technique, recanalization was successful in five of the six occlusions. One occlusion was too long to traverse safely in one patient. Two patients were asymptomatic 16-18 months after the recanalization. CONCLUSION: This new technique offers an effective alternative to surgery in the treatment of central venous occlusion.

Aged↗
PubMed1999

Imagery content during nonpharmacologic analgesia in the procedure suite: where your patients would rather be.

RATIONALE AND OBJECTIVES: Imagery as a hypnotic technique can produce analgesia and anxiolysis, but effective use may be restricted to select, highly hypnotizable individuals. This study assessed (a) whether patients not selected for hypnotizability can produce imagery during interventional radiologic procedures and (b) the type of imagery produced. A secondary goal of the study was to familiarize health care providers with a simple, time-efficient technique for imagery. MATERIALS AND METHODS: Fifty-six nonselected patients referred for interventional procedures were guided to a state of self-hypnotic relaxation by a health care provider according to a standardized protocol and script. Patient hypnotizability was assessed according to the Hypnotic Induction Profile test. RESULTS: Patients as a group had average distribution of hypnotizability. The induction script was started in all patients and completed in 53. All patients developed an imagery scenario. Chosen imagery was highly individual, but common trends were nature and travel, family and home, and personal skills. Being with loved ones was an important element of imagery for 14 patients. Thirty-two patients chose passive contemplation, and 24 were action oriented. CONCLUSION: Average patients who present for interventional radiologic procedures and are not preselected for hypnotizability can engage in imagery. Topics chosen are highly individual, thus making prerecorded tapes or provider-directed imagery unlikely to be equally successful.

Adult↗
PubMed1997

Educating interventional radiology personnel in nonpharmacologic analgesia: effect on patients' pain perception.

RATIONALE AND OBJECTIVES: The purpose was to evaluate the effects on patients' pain perception of educating interventional radiology personnel in nonpharmacologic analgesia. MATERIALS AND METHODS: Ninety-six patients undergoing lower-extremity arteriography or percutaneous nephrostomy were asked to rate the pain they experienced during the procedure on a scale of 0 to 5 (0 = no pain, 1 = mild pain, 2 = moderate pain, 3 = severe pain, 4 = very severe pain, 5 = worst pain possible). Patients were studied at two baseline sessions (baseline 1, December 1993 to August 1994, n = 15; and baseline 2, September 1995 to January 1996, n = 11) and after the staff underwent one of two training sessions (posttraining 1, January 1995 to July 1995, n = 34; posttraining 2, January 1996 to April 1996, n = 36). Training targeted nurses and technologists and included rapport skills, correct use of language and suggestions, distraction, relaxation training, and self-hypnosis. Data were evaluated with analysis of variance for repeated measures. RESULTS: The mean pain scores reported after training were lower (1.48) and matched an "acceptable" pain score of 1.52 more closely than those reported under baseline conditions (2.54, P = .001). There was a tendency toward reduced use of intravenously administered agents for conscious sedation after training. There were no statistically significant differences in the pain scores between patients who underwent arteriography and patients who underwent nephrostomy overall (1.76 and 1.78, respectively), at baseline (2.58 and 2.43, respectively), and after staff training (1.49 and 1.42, respectively). CONCLUSION: Interventional radiology personnel trained in nonpharmacologic analgesia methods can help reduce patients' pain perception during interventional procedures.

Analgesia↗
PubMed1997

Intercostal artery aneurysm associated with coarctation of the aorta: specific finding on MR imaging.

Aneurysm formation has been described in association with aortic coarctation in approximately 10% of patients. The incidence increases with age and reaches 42% in patients over 40 years of age. To our knowledge, only six radiologic reports have described aortic coarctation in association with an intercostal artery aneurysm and none of these reports has described an intercostal artery entering the aneurysm. We present a case in which MR imaging helped identify this unusual abnormality.

Adult↗
PubMed1997

[Stent-graft placement for saccular aortic aneurysm: case reports].

Stent-graft placement was performed in 2 patients with saccular aortic aneurysm. A Dacron-covered nitinol stent-graft was deployed in the thracoabdominal and infrarenal abdominal aorta. These procedures were successfully performed. The aneurysm disappeared on intraoperative angiogram immediately after deployment. Follow-up CT showed thrombosis or disappearance of aortic aneurysm. Distal embolization occurred in one patient, who required resection of the small bowel on the following day and renal dialysis due to renal infarction. Both patients were still alive one and a half years and one year after the procedure, respectively. Stent-graft placement is a feasible alternative to surgery for aortic aneurysm in selected patients.

Aged↗
PubMed1996

1996 AUR Memorial Award. Densitometric analysis of eccentric vascular stenoses: comparison of CO2 and iodinated contrast media.

RATIONALE AND OBJECTIVES: The authors compared the accuracies of CO2 and iodinated contrast material in the densitometric quantification of eccentric vascular stenoses. METHODS: Five precision-machined eccentric phantom stenoses of 50%, 60%, 70%, 80%, and 90% cross-sectional area narrowing were integrated into a pulsatile ex vivo flow model, imaged with digital subtraction angiography (DSA), and analyzed with densitometry. Relationships between the actual and measured (densitometric) degree of cross-sectional area narrowing were evaluated by using linear regression analysis and paired Student t tests. Comparison measurements were obtained in en face and profile projections. In addition, the effect of iodinated contrast material concentration was evaluated over a range of dilutions (47-282 mg iodine per milliliter). RESULTS: CO2 yielded significantly more accurate results than did iodinated contrast material (282 mg iodine per milliliter) in the 50%, 60%, and 70% stenosis models when imaging was performed en face (P < .005). The best overall correlation was observed with CO2 DSA when imaging in profile (slope = 0.91, intercept = 2.42% actual stenosis, r = .99). The accuracy of densitometric stenosis estimation was inversely related to the concentration of iodinated contrast material. CONCLUSION: CO2 DSA densitometry, under the conditions of these experiments, yields quantitative measures of relative cross-sectional area narrowing that are comparable with, and under some circumstances surpass, those obtained with iodinated contrast material-based DSA. In this model, CO2 was more useful than iodinated contrast material in 50%-70% stenosis when imaging in the least-optimal plane of stenosis quantification, the en face projection.

Absorptiometry, Photon↗