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Biomedical subjects

G Lund

Publications and source records attributed to G Lund.

At least 73 records · Page 4Linked to original sources

Balloon dilatation of benign biliary strictures.

Percutaneous transhepatic balloon dilatation of benign postoperative biliary strictures was performed in 6 patients. The procedure was curative in 1 patient. These findings indicate the need for repeated long-term, high-pressure dilatation of these strictures, using an inflation device and pressure gauge. Large catheters should be left in place as stents. Early non-surgical management may improve the salvage rate of this surgical complication.

Adult↗

A new vena caval filter for percutaneous placement and retrieval: experimental study.

A new vena caval filter that can be inserted percutaneously through an angiographic catheter is described. The filter is secured by controlled penetration of the caval wall and is designed for percutaneous retrieval. The filter was easily and safely placed and removed in 11 mongrel dogs, and in an in vitro study, the filter was shown to be highly effective and less dependent than the Greenfield filter on positioning. The authors believe that the filter will be suitable for prophylactic placement in patients at high risk for pulmonary thromboembolic disease.

Animals↗

Nephrotoxicity of contrast media assessed by occlusion arteriography.

The authors describe an experimental model for the study of nephrotoxicity induced by contrast media, based on a standardized injection combined with occlusion of the renal artery so as to expose the kidney to a high concentration of contrast medium for ten minutes. Iopamidol, ioxaglate, and both isosmolar and hyperosmolar saline were well tolerated, but diatrizoate caused marked radiological and pathological changes. This model may be helpful in studies of the mechanisms underlying contrast medium nephrotoxicity and evaluating differences in toxicity between contrast agents.

Animals↗

Long-term patency of the ductus arteriosus after balloon dilatation: an experimental study.

Balloon dilatation of the ductus arteriosus was carried out in vivo in eight piglets that were 12 to 16 days old. The ductus was functionally closed in all animals before dilatation. Long-term patency for periods of up to 6 months after the procedure was demonstrated in six animals by angiography, Doppler ultrasound examination, and at autopsy. The presence of hemodynamically significant shunts was indicated by clinical development of heart failure, pulmonary infections, and left ventricular hypertrophy. These results confirm the value of this laboratory preparation to create left-to-right shunts at the ductus level.

Angioplasty, Balloon↗

Role of ischemia in contrast-induced renal damage: an experimental study.

Total and regional cortical blood flow was measured in dogs by the radioactive microsphere technique after renal damage of varying severity had been induced by combining selective injection of diatrizoate, iopamidol, or normal saline with a 10 min occlusion of the renal artery. There was extensive tubular and glomerular damage in the kidneys exposed to diatrizoate, but not in the kidneys exposed to saline. Iopamidol caused intermediate changes. Average cortical blood flow was reduced from baseline levels in all groups 5 min after perfusion was restored. After 1 hr the flow had returned to the baseline level. Analysis of variance did not show a statistically significant difference among the groups. A tendency for redistribution of flow from outer to inner cortical layers was seen, but this was present in all groups. The flow changes detected in this study cannot explain the varying severity of renal damage.

Animals↗

Effect of prostaglandin inhibition on the renal vascular response to ionic and non-ionic contrast media in the dog.

In an attempt to study the role of prostaglandins in the renal vascular response to contrast media in mongrel dogs, renal arterial injections of 6 ml of either the non-ionic contrast medium Iopamidol or the ionic medium diatrizoate meglumine/Na+ were performed, before and after intravenous injection of a buffered solution of acetylsalicylic acid (10 mg/kg) (ASA). Renal blood flow was recorded using non-occluding electromagnetic flow probes. The resting renal blood flow was significantly reduced after ASA. The usual biphasic response to contrast injection was observed both before and after ASA, and using either contrast medium. Analysis of the results failed to show any difference in degree of vasodilation or vasoconstriction after ASA. We conclude that prostaglandins may affect the resting level of renal blood flow but are not mediators of the instantaneous changes in response to contrast injection.

Animals↗

The adhesiometer: a simple device to measure adherence of barium sulfate to intestinal mucosa.

A simple, inexpensive device assessing barium sulfate adherence to alimentary tract mucosa was tested in an animal study using pigs and dogs. Interaction of gastric, intestinal, and colonic mucosal lining with three different barium preparations was studied. In both pigs and dogs, barium adherence to gastric mucosa was significantly stronger when compared with colonic mucosa.

Animals↗

A logical approach to renal stone removal.

On the basis of experience with over 350 percutaneous stone extractions, a logical approach assuring a high success rate and minimizing complications is described. The importance of the position of the kidney in the body, the caliceal anatomy, the renal arterial anatomy, and the instrumentation used on puncture site selection are discussed. Strategies for removal of caliceal, pelvic, ureteral, and staghorn calculi, rationale, and treatment of complications are also described.

Humans↗

Percutaneous transluminal angioplasty for treatment of renal artery stenosis in children.

Angioplasty was carried out in four children with hypertension and renal artery stenosis, including one patient with neurofibromatosis and one patient with multiple arterial stenoses. Two patients did not respond. In the patient with neurofibromatosis the stenosis persisted unchanged despite multiple balloon inflations. In one patient hypertension persisted despite successful dilatation, and was probably related to longstanding contralateral kidney disease. Two patients had excellent blood pressure response to dilatation. One of these patients required redilatation of bilateral recurrent stenoses.

Adolescent↗

Circulating immune complexes in patients with acute measles and rubella virus infections.

A solid-phase C1q radioimmunoassay was used to test for immune complexes (ICs) in sera obtained longitudinally from patients recovering from acute, uncomplicated measles and rubella virus infections. ICs were detected in 12 (18.5%) of 65 sera from 14 measles patients who did not have prolonged IC formation. Of 12 IC-positive measles sera, 9 were collected 4 weeks or more after rash onset. Transient appearance of detectable circulating ICs occurred sooner in 22 rubella patients who did not have prolonged IC formation. Of 109 rubella sera, 14 (12.8%) were IC-positive, and, of these, 10 were collected within 3 weeks of rash onset. Prolonged IC formation was found for an additional four measles and two rubella virus patients. Fractionation of sera from these six patients revealed that levels of large-sized ICs were highest in the initial 10 days after rash onset. Levels of large-sized ICs then declined to those for medium- and small (approximately immunoglobulin G)-sized ICs. IC-associated virus-specific antigens were detected in some of the sera from the six patients having prolonged IC formation. These results suggest two things: first, measles and rubella virus patients differ in the timing of virus clearance or in the reestablishment of normal immunity after infection; second, virus clearance is prolonged in some measles and rubella virus patients who have seemingly normal recoveries from their infections.

Acute Disease↗

Nonsurgical placement of arterial endoprostheses: a new technique using nitinol wire.

A new type of endovascular prosthesis has been developed using a unique metal alloy (nitinol) with a heat-sensitive memory. Nitinol wire coil grafts were straightened in ice water and passed into the canine aorta via catheter, where they reformed into their original shapes. Follow-up aortograms demonstrated long-term patency with minimal thrombus formation. Nitinol endovascular coil grafts may eventually be used in the nonsurgical treatment of several forms of vascular disease.

Alloys↗

Detachable stainless-steel spider. A new device for vessel occlusion.

A new device for transcatheter vessel occlusion consists of a stainless-steel spider which can be screwed onto a threaded guide wire. Since the spider can be retrieved after it is extruded from the catheter, accurate placement is possible. The device was tested in the aorta and pulmonary artery of dogs. The spider blocked the movement of steel coils and wool streamers and occluded the vessel. This device is particularly useful for occlusion of large arteriovenous fistulas in the lungs.

Animals↗

Patency of the ductus arteriosus after balloon dilatation: an experimental study.

Balloon dilatation of the ductus arteriosus was carried out in vivo in newborn pigs and on postmortem specimens from humans and piglets. The ductus was functionally closed in all newborn animals but patency resulted in all animals after balloon dilatation. Left-to-right shunts of 50% to 70% were found with anatomic lumen sizes of 3 to 5 mm. Patency was demonstrated up to 6 weeks after dilatation. Histologic examination showed splitting of the internal elastic layer and media, areas of hemorrhage confined to the media, and preservation of the adventitia. Mediastinal hemorrhage did not occur. This new technique is useful as an animal model of patent ductus arteriosus and could theoretically be used for palliative treatment of ductus-dependent congenital heart disease.

Angioplasty, Balloon↗

A new percutaneous vena cava filter.

A new, percutaneous vena cava filter was developed and tested in 11 dogs. Nitinol wire (0.045 cm diam) spirals were straightened and passed through an 8 French Teflon catheter into the inferior vena cava. The filter resumed its original spiral shape on warming to body temperature and was left in place up to 6 weeks. Long-term patency and capture of injected radiopaque clots were demonstrated. This new filter design may be a simple alternative to currently used implants.

Animals↗