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Biomedical subjects

A H Cragg

Publications and source records attributed to A H Cragg.

At least 19 recordsLinked to original sources
PubMed1992

Management of infrainguinal occluded vein bypasses with a combined approach of thrombolysis and surveillance. A prospective study.

Intra-arterial thrombolysis with urokinase was attempted on 23 occluded infrainguinal vein bypasses. Lesions revealed by thrombolysis included 11 anastomotic stenoses, five midbypass stenoses, five native artery stenoses, and five unusable diffusely stenotic vein conduits. Adjunctive procedures performed immediately after successful thrombolysis included 10 local surgical revisions, five balloon angioplasties, and five new vein bypasses. Three nonanastomotic vein bypass stenoses and two common iliac artery stenoses were detected using a surveillance protocol in subsequent follow-up of patients with patent bypasses. Twelve-month patency following thrombolysis (including immediate failures) was 52.4%. The use of thrombolysis in the management of occluded vein bypasses allows the identification and correction of pathological lesions. Once revised, continued vein bypass patency may be improved with a surveillance program.

Angioplasty, Balloon↗
PubMed1992

Effect of antineoplastic agents on smooth muscle cell proliferation in vitro: implications for prevention of restenosis after transluminal angioplasty.

The effect of several antineoplastic agents on vascular smooth muscle cell proliferation was studied in vitro. Both fluorouracil and cytarabine produced significant concentration-dependent inhibition of smooth muscle cell proliferation in cultured porcine pulmonary artery in vitro, while cyclophosphamide stimulated growth. For fluorouracil, inhibition was near maximal at a concentration of 13.0 microgram/mL and was seen with both coincubation and 2-hour preincubation of fluorouracil with quiescent cells. Fluorouracil is a promising agent for inhibition of intimal proliferation. Further work is warranted to determine its effect in vivo.

Angioplasty, Balloon↗
PubMed1992

Comparison of the efficacy of digital subtraction and film-screen angiography of the lower limb: prospective study in 50 patients.

We prospectively compared current digital subtraction angiography (DSA) with conventional film-screen angiography (FSA) of the lower limb for evaluation of areas of arterial stenosis and degree of arterial visualization. Fifty patients had both DSA and FSA of a single lower limb. Specific anatomic sites (examiner-selected sites) throughout the lower limb were marked on each film by an experienced angiographer (examiner). These sites consisted of the common femoral, superficial femoral, popliteal, anterior tibial, posterior tibial, peroneal, and dorsalis pedis arteries and bypass grafts, when present. The films were then reviewed blindly by two different experienced angiographers (observers). All sites were graded for the degree of arterial narrowing based on a standard scale (grade 1 = normal, grade 5 = occluded) that also included grading for nonvisualization (grade 6). Each observer also selected the most stenotic site in each anatomic area (observer-selected sites). The data were analyzed for the entire lower limb and at specific anatomic sites. DSA sites were judged to be slightly more narrowed (p less than .05) in the superficial femoral artery by both observers and in the common femoral artery, bypass graft, and overall by a single observer. No other significant differences were found in grade of stenosis or vessel visualization for examiner-selected sites. For observer-selected sites, observers agreed on the location of the most stenotic site 76% of the time for FSA and 69% of the time for DSA. No significant difference was found in grade of stenosis or vessel visualization for either observer for the entire lower limb or at specific anatomic sites. These findings were present when all sites chosen were considered and when there was agreement between sites chosen on FSA and DSA for each observer. In conclusion, optimal-quality FSA and DSA produced virtually equivalent results for angiography of the lower limb for both grade of stenosis/occlusion and vessel visualization.

Angiography↗
PubMed1991

Hematoma formation after diagnostic angiography: effect of catheter size.

The authors studied the effect of catheter size on the development of hematomas after catheterization. Four hundred ninety-nine patients who underwent routine diagnostic angiography were randomized to receive either 5-F or 7-F catheters. Small hematomas were more frequent in the 7-F catheter group (P less than .05); however, there was no difference in the frequency of larger hematomas between groups. Compression time was slightly but significantly (P less than .001) longer in the 7-F group. When catheter size; duration of the procedure; and patient age, weight, blood pressure and coagulation status were considered as independent variables, patient weight was the most accurate predictor of hematoma formation. The authors conclude that catheter size does not affect the development of a clinically significant hematoma after diagnostic angiography and that other factors such as patient weight are more important in this regard.

Angiography↗
PubMed1991

Time course of satisfaction of search.

"Satisfaction of search" (SOS) refers to the effect in which a second lesion remains undetected after detection of another lesion on the same radiograph. The objective of this study was to clarify our understanding of SOS by relating it to total time of inspection and time intervals before, between, and after discovery of lesions. Detection accuracy of native lesions in chest radiographs, before and after the addition of a simulated nodular lesion, was measured for ten observers. Analysis of data from this and a previous experiment showed that average perceptual accuracy of individual receiver operating characteristic curves was significantly reduced with the addition of the nodules. Plots and analyses of search time revealed that, on average, during a typical 46-second inspection of a case, simulated nodules were found at 18 seconds, native abnormalities at 25 seconds, and false positives occurred at 33 seconds. Time needed to find nodules did not depend on whether native lesions were present; time to find native lesions did not change with addition of nodules; and total search time was the same for images with one, two, or no lesions. The detection results show that the SOS effect was obtained, but that interrupting search in order to measure it also diminishes accuracy. Analysis of the time course data relates SOS to perceptual capture and strategic halting of search.

Diagnostic Errors↗
PubMed1991

Two urokinase dose regimens in native arterial and graft occlusions: initial results of a prospective, randomized clinical trial.

The effects of two urokinase (UK) dose regimens on lysis time, lytic success, primary clinical success, and frequency of complications of peripheral thrombolysis were compared. Seventy-two intraarterial UK infusions were performed by means of standard catheter-directed infusion techniques in 63 patients with symptomatic peripheral arterial or bypass graft occlusions. Patients were prospectively randomized to high-dose (250,000 U/h for 4 hours and then 125,000 U/h) or low-dose (50,000 U/h) regimens. The mean time to complete lysis was 20.8, 26.0, 16.5, and 18.2 hours for the high-dose artery, low-dose artery, high-dose graft, and low-dose graft groups, respectively (P was not significant). Respective mean infusion durations were 27.1, 35.4, 22.2, and 25.3 hours. Clinical success was achieved in 65%-85% of cases. The frequency of complications was equivalent between groups, except for a higher frequency of minor bleeding complications in the high-dose group. The two urokinase dose regimens studied were equally effective in enabling peripheral thrombolysis.

Angiography↗
PubMed1991

Nephrotoxicity from contrast material in renal insufficiency: ionic versus nonionic agents.

Controversy exists over whether use of low-osmolality contrast agents is of any benefit in mitigating the risk of contrast material-induced nephrotoxicity (CN) in patients with impaired renal function. To test this hypothesis, 101 adult inpatients with high serum creatinine levels (range, 1.4-2.4 mg/dL [120-210 mumol/L]) undergoing contrast material-enhanced computed tomography were randomized to receive ionic or nonionic (low-osmolality) contrast agents in a uniform dose. Changes in serum creatinine level at 48 hours were measured. Seven (14%) of the 50 patients receiving ionic contrast media experienced an increase of 25% or more in serum creatinine level. Only one (2%) of the 51 patients receiving nonionic contrast agents experienced such an increase, a statistically significant difference (P less than .05). In the subset of 25 diabetic patients, the difference was of a similar magnitude. These data suggest that ionic contrast media are more likely than nonionic contrast agents to cause mild exacerbation of renal insufficiency when given intravenously. However, there were no cases of clinically important CN in the study.

Adult↗
PubMed1991

Randomized double-blind trial of midazolam/placebo and midazolam/fentanyl for sedation and analgesia in lower-extremity angiography.

Safety and efficacy of two drug regimens used for sedation and analgesia during lower-extremity angiography were studied. Midazolam (loading dose 14.5 micrograms/kg; maintenance dose, 7.2 micrograms/kg) with or without fentanyl (loading dose, 0.725 micrograms/kg; maintenance dose, 0.362 micrograms/kg) was administered in a blind fashion as an IV bolus to 50 patients. Hemodynamic responses were monitored, and a standardized questionnaire was given to the patient before, immediately after, and 8-24 hr after the procedure. Physicians also were asked questions after the procedure. Heart rate and oxygen saturation were not significantly different before and 2 min after administration or between groups. A small but significant decrease in blood pressure occurred 2 min after the loading dose was given in both groups. Both drug regimens had statistically significant anxiolytic effects; however, anxiolytic effects were superior in the midazolam/fentanyl group (p less than .02). Patients rated the overall effectiveness of anesthesia with midazolam/fentanyl as superior (p less than .02). Analysis of physicians' judgments of the effectiveness of sedation and analgesia showed a statistically significant advantage for the midazolam/fentanyl group (p less than .01). We conclude that midazolam/fentanyl appears to be as safe as and more efficacious than midazolam alone for sedation and analgesia during lower-extremity angiography.

Angiography↗
PubMed1990

Thermal balloon angioplasty in a canine model: preliminary results.

Preliminary results suggest that thermal balloon angioplasty (BA) may produce plaque welding, decreased elastic recoil, and increased luminal caliber. The authors report results of a simple method of thermal BA in a canine model. Seven mongrel dogs (15-25 kg) underwent conventional BA of each iliac artery with balloons that were 1-2 mm larger than the vessel lumen. The balloons were then perfused with a mixture of saline and contrast material at either 25 degrees C (control) or 100 degrees C for 1 minute. Compared with baseline measurements, thermal BA produced greater lumen enlargement (+16.7%) than control BA (+3.4%) immediately after the procedure (P less than .05). This trend persisted in vessels studied after a delay of 2, 4, or 12 weeks. Histologic sections from specimens studied after a delay demonstrated intimal hyperplasia in both the thermally treated and control arteries. Medial sclerosis was consistently seen in the thermally treated arteries. The authors conclude that thermal BA results in immediate and delayed increases in arterial diameter compared with conventional BA due to decreased elastic recoil and medial sclerosis.

Angioplasty, Balloon↗
PubMed1990

Peripheral atherectomy: experimental results with a new device.

The size of present rotational atherectomy devices is limited in part by a tendency to produce vessel torsion. The authors designed and investigated a large-bore rotational atherectomy device for peripheral atherectomy in a single pass without significant torsion. A plaque was retrieved from 36 of 40 cadaveric iliac arteries. The mean plaque size was 8.4 x 3.9 mm, and the average number retrieved per artery was two. Thirty of 34 severely calcified arteries were treated successfully. Effluent study revealed no distal embolization; however, six perforations and four dissections occurred. Preliminary results suggest that a cutting surface with a relatively large diameter can be designed to be effective without producing vessel torsion. Changes in future designs will include added flexibility and expandable cutting surfaces to enhance safety and minimize entry diameter.

Arteriosclerosis↗
PubMed1990

Plaque modification with tetracycline: enhanced tissue ablation with the excimer laser.

Tetracycline has been shown to collect selectively in atherosclerotic plaque and is a known photosensitizing agent. To determine if tetracycline enhances the photoablative effects of the ultraviolet xenon-fluorine excimer laser, the authors exposed four cadaveric aortic samples to tetracycline and four to only normal saline. Ninety-three sites in the samples were subjected to laser energy and analyzed with light microscopy for crater depth and width and for degree of thermal injury. Forty-three of the sites were histologically normal, and 50 were atherosclerotic. Crater depth did not differ significantly in atherosclerotic and normal sites not exposed to tetracycline. Atherosclerotic sites exposed to tetracycline showed significantly deeper craters compared with those in normal, exposed sites. The effects of tetracycline exposure and histologic characteristics (normal vs atherosclerotic) on crater width and thermal injury were independent and additive. When the excimer laser is used for treatment, tetracycline can definitely enhance atherosclerotic plaque ablation.

Aorta↗
PubMed1990

New guide wire for high-flow infusion.

A new open-ended guide wire with a large internal diameter was compared with two other open-ended guide-wire and catheter infusion systems. Simple experiments were performed to compare flow rates and ability to track. The larger internal diameter of the new wire allowed higher flow rates and accepted an 0.025-inch (0.64-mm) guide wire. The flexibility of the new infusion wire was shown to be equivalent to that of the catheter system. The authors conclude that the new wire has advantages in terms of flow rates and ability to track, compared with presently available infusion systems.

Catheterization↗
PubMed1990

Techniques for lower-limb angiography: a comparative study.

Three separate variables--volume of contrast material, site of contrast material injection, and arterial inflow occlusion--were tested in a prospective, randomized fashion in 52 patients to determine the best technique for lower-limb angiography. Twelve patients received 30 and 60 mL of contrast material injected at the level of the external iliac artery (EIA), 20 patients received 60 mL injected at the level of the EIA with and without inflow occlusion, and 20 patients received 120 mL injected at the level of the aortic bifurcation and 60 mL injected at the level of the EIA. A total of 104 angiograms were obtained, two in each patient. Two examiners reviewed all angiograms in a blinded fashion, initially as 104 separate studies for diagnostic adequacy (ie, the need for additional angiography) and then as 52 paired studies for direct comparison of the quality of arterial filling (ie, the best-appearing angiogram). The 60-mL studies were significantly better (P less than .001) in both categories when compared with both the 30- and the 120-mL studies. There was, however, no significant difference between the 60-mL studies with and without inflow occlusion. The authors conclude that the best screen-film lower-limb angiograms are obtained with large volumes (60 mL) of contrast material injected below the pelvic vessels (EIA).

Adult↗
PubMed1989

Vascular applications of laser.

The authors review the current experimental and clinical literature relating to the use of lasers in peripheral vascular disease. During the past few years, significant strides have been made in effective harnessing of laser energy for percutaneous revascularization. However, the role of lasers in treating vascular disease is not yet clear. Thus current application of laser technology in this area should be considered experimental until adequate clinical studies confirm its efficacy.

Angioplasty, Balloon↗
PubMed1989

Thrombus-trapping efficiency of the Greenfield filter in vivo.

A total of 100 radiopaque blood clots were injected into seven adult sheep under fluoroscopic observation to assess the clot-trapping efficiency of the Greenfield vena caval filter. Eleven percent of the clots passed through the filter, with all failures limited to the two smallest clot sizes: 4 x 10 mm (five of 25) and 4 x 30 mm (six of 25). The Greenfield filter was 100% efficient in trapping larger clots (8 x 10 mm and 8 x 30 mm). There was a tendency toward poorer clot-trapping performance when the Greenfield filter was tilted within the vena cava, but this was not significant. There were no significant differences in hemodynamic measurements obtained immediately before and after injection of each clot, and no significant changes were noted in the animal's hemodynamic status or in blood gas measurements in those cases in which the clots passed through the filter. Since the caval diameter in sheep approximates that in humans, the authors conclude that the Greenfield filter in the clinical setting is capable of stopping large, likely fatal, emboli and a large number of smaller, possibly less clinically significant, emboli.

Animals↗
PubMed1989

Political trends in vascular and interventional radiology: a randomized survey.

There is a trend in the United States toward the performance of vascular and interventional radiology procedures by nonradiologists. A survey was conducted of 2.069 U.S. radiologists to define better the current status of and gather opinions on the future of vascular and interventional radiology. A total of 715 (35%) completed questionnaires were returned. Cross tabulations among subgroups of respondents were performed to address key issues. The median proportion of time spent in the performance of vascular and interventional radiology was 10%, and 51.5% of the radiologists surveyed were in groups that included a fellowship-trained interventional radiologist. More than half (54.4%) of the radiologists indicated that nonradiologists have expressed interest in performing vascular and interventional techniques. According to 13.4% of the radiologists surveyed, cardiologists performed at least some peripheral angiography or angioplasty. The vast majority of radiologists (96.8%) did not want other specialties to assume vascular and interventional radiology procedures, but 16.8% believed these procedures will eventually be lost to other specialties. The results indicate that vascular and interventional radiology is being infringed on to a relatively large degree by other specialties.

Attitude of Health Personnel↗
PubMed1989

Thrombosed polytetrafluoroethylene hemodialysis fistulas: salvage with combined thrombectomy and angioplasty.

Combined thrombectomy and angioplasty was performed for 19 thrombosed polytetrafluoroethylene grafts. Patency for more than 1 week was achieved in 16 of the 19 grafts (84%). The average duration of graft function after angioplasty in all 19 grafts was 7.1 months (range, 0-32.3 months). Eleven of the 19 grafts (58%) were functioning 5 months after the procedure; seven are still functioning. Combined thrombectomy and angioplasty offers a viable alternative to thrombolytic therapy or complete surgical revision.

Adult↗