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Biomedical subjects

K Amplatz

Publications and source records attributed to K Amplatz.

At least 91 records · Page 5Linked to original sources
PubMed1986

Relation between Q-QS changes on the rest electrocardiogram and left ventricular function with healed myocardial infarction.

In the Program of Surgical Control of Hyperlipidemia, the relation of the Minnesota Q-QS codes for rest electrocardiograms to left ventricular (LV) function was studied in patients with healed myocardial infarction (MI). Of 838 subjects enrolled in the study, 477 (57%) had codable Q-QS patterns at the time of randomization. There was an extremely high correlation between the level of the Minnesota code and concurrent LV function, the latter being determined on left ventriculography by both ejection fraction and the number of segmental wall motion abnormalities. Subjects without a Q-QS code had less myocardial damage than did those with a code present in a single cardiac area. Extent of LV damage correlated with the level of significance of the Q-QS code, and when the code was present in only 1 cardiac location damage was greatest if the anteroseptal area was involved. Q-QS codes present in 2 rather than 1 cardiac area were associated with an even greater degree of LV damage. A previous study has shown a strong correlation between LV function and the Minnesota codes when the latter were recorded 0.5 to 5 years (mean 2.2) earlier at the time of the acute MI. The present data show that the relation between LV function and the Minnesota codes after an acute MI persists over time and is even stronger when both are determined in the healed state at a time remote from the acute event.

Adult↗
PubMed1986

Percutaneous techniques for the management of caliceal diverticula containing calculi.

Most frequently caliceal diverticula are found incidentally on routine excretory urograms. Smaller diverticula are associated with a low incidence of complications but larger diverticula with a narrow communication to the main collecting system will predispose to calculous formation as a result of stasis of urine within the diverticulum. The techniques used and results achieved in 10 patients with such calculi who have been successfully managed percutaneously are discussed. Particular reference is made to techniques used specifically to obliterate the diverticula.

Adult↗
PubMed1986

[Expansion, deformation and bursting characteristics of commonly used balloon dilatation catheters. In vitro studies (1)].

We evaluated the characteristics of dilatation and deformation, as well as pressure requirements, bursting point, and type of bursting of the five most common balloon dilatation catheters. Polyvinyl chloride, polyethylene, and polyurethane-nylon balloons from 4 different manufacturers were examined in water-baths and an arrangement of tightly fitting teflon tubes. Defined balloon inflations were monitored and documented until balloon rupture occurred. Significant differences were found according to the different constructions and materials of the balloon catheters. Modern PVC showed a quality equal to PE material. Marked and clinically relevant differences of balloon compliance and behaviour in the water baths and within teflon tubes were demonstrated.

Angioplasty, Balloon↗
PubMed1986

[Expansion, deformation and bursting characteristics of frequently used balloon dilatation catheters. In vivo studies on canine vessels (2)].

In an experimental angioplasty study in dogs, we evaluated the characteristics of dilatation and deformation, as well as the pressure requirements, bursting points, and types of bursting of four different balloon dilatation catheters. The balloons, which were selected 0%, 30%, and 80-100% larger than the arterial lumen, measured 4, 6, and 8 mm in diameter and were inflated with an automated pump which simultaneously recorded balloon pressure and volume. Changes to the vessel wall were assessed radiographically and by histology. In vivo, balloon dilatation catheters demonstrated a markedly different behaviour than in vitro. Significantly higher pressures were tolerated due to the support of the arterial sleeve. Non-compliant oversized balloons caused more damage to the arterial wall than compliant ones. Oversized balloons attained their required diameters only with high inflation pressures of 10 to 12 atm or after rupture of the artery.

Angioplasty, Balloon↗
PubMed1986

The double puncture: an effective percutaneous technique for removing complex, multiple renal calculi.

Percutaneous nephrostolithotomy, which can require a double puncture, is presently the method of choice in our institution for the removal of renal stones. Patients that underwent this procedure were evaluated to identify the possible reasons for the double puncture. Of 200 patients evaluated, 14 needed a second tract. The three variables that determined whether a second puncture was needed, in order of importance, were number and size of the stones, with second tracts needed in patients with multiple stones and staghorn calculi; anatomical variations of the renal collecting system itself, with bifid systems the most significant anatomic variation; and the dexterity of the radiologist in performing the puncture and the ability of the urologist to extract the stone. Second tracts were needed more frequently in patients who presented with stones in both the lower and middle poles of the collecting systems.

Humans↗
PubMed1986

Movable core guide wire: evaluation of improved model.

Six commercially available movable core guide wires were compared with each other and with a new design in glass models simulating tortuous vessels. The results demonstrate a wide variability in performance of the commercially available wires and the superiority of the new design.

Angiography↗
PubMed1986

Surface shield: device to reduce personnel radiation exposure.

A simple device is described that can reduce personnel exposure from scatter radiation by up to 75%. The device consists of an oblong piece of shielding (0.75-mm lead equivalent) that is taped to the side of the patient during percutaneous renal stone removal and other interventional procedures. Contrary to other shields and barriers, this does not interfere with access to the patient. Scatter exposure data from phantom studies are presented and the rationale for surface shielding discussed.

Humans↗
PubMed1986

A new retention catheter.

A new retention catheter made of a soft, biocompatible material is described. It has the advantages of the Cope- and Malecot-type systems without their inherent disadvantages. It is easily introduced into virtually any fluid collection and is optimal for smaller collections, such as a normal renal pelvis.

Catheterization↗
PubMed1986

Urine-compatible polymer for long-term ureteral stenting.

Internal double-J ureteral stents were designed from a urine-compatible polymer (C-Flex), and 35 stents were placed in patients. The overall patency rate for the stents was 80%, with most stent failures occurring before 2 months; the follow-up period ranged from 2 to 16 months, with a mean follow-up for all stents of 5.0 months. Stents were considered patent at last follow-up only if they had been in place for at least 2 months. No migration or fracture of the stents occurred. Physical properties of urine-exposed stents were compared with those of virgin tubing and tubing exposed for 1 year to shelf conditions. Stent patency was optimized by increasing urine flow by increasing the patient's voluntary oral intake, administering prophylactic oral antibiotics, and avoiding placement of stents into grossly bloody or infected collecting systems.

Adult↗
PubMed1986

New super-stiff guide wire.

A super-stiff spring guide wire is described, which overcomes some of the drawbacks of the Lunderquist-Ring guide wire. The new wire couples maximum stiffness with a smooth, gradual transition to a floppy tip, thus decreasing the likelihood of breakage and organ perforation.

Radiography↗
PubMed1986

Coil-in-coil technique for vascular embolization.

A new technique for vascular embolization using two Gianturco steel coils is described. The authors used a "coil-in-coil" technique to embolize the arteries of 12 dogs. In this technique a large coil is introduced into the artery followed by a smaller coil, which is delivered with a special introducer into the lumen of the first coil. Two coils can therefore be introduced into a shorter length of vessel. This method was as effective as "packing" the vessel with two coils in a row. The coil-in-coil technique is especially advantageous for use in infants and children with short, anomalous vessels, minimizing the risk of coil dislodgment into normal peripheral vessels.

Animals↗
PubMed1986

Experience with the Amplatz retrievable vena caval filter. Work in progress.

The Amplatz retrievable vena caval filter was designed in an attempt to decrease complications associated with the placement of Mobin-Uddin or Kimray-Greenfield filters. The design allows percutaneous retrieval, thus expanding application of the filter to situations requiring temporary prophylaxis against pulmonary embolism. Filters have been placed in 16 patients, nine (56%) for prophylactic purposes. All filters were easily inserted percutaneously. Complications occurred in three patients; these included complete thrombosis of the inferior vena cava below the filter, misplacement of one filter into the pericaval retroperitoneal tissue, and development of thrombus cranial to the filter. With the current introduction system, the possibility of filter misplacement has been essentially eliminated. No patient experienced symptoms suggestive of pulmonary embolism after filter insertion. One filter retrieval has been performed, with no complications.

Adult↗
PubMed1986

Angiographic and interventional radiologic considerations in liver transplantation.

Of 46 liver transplantations performed, 15 patients are alive at follow-up intervals from 2 to 50 months. The most common indications for liver transplantation were biliary atresia, cirrhosis, and neoplasia. About 50% of the patients had pre- and/or postoperative angiograms. Additional material was available from pretransplant workups in patients subsequently shown to be unsuitable for transplantation. Of 13 preoperative angiographic studies, portal vein patency was confirmed in two, inferior vena caval (IVC) patency was confirmed in two, and diffuse neoplasm was identified in three. These patients subsequently had transplants. Conditions precluding liver transplantation in six patients were inadequate portal vein size (less than 5 mm) in two, occluded IVC or portal vein in one each, nonvisualized portal vein in one, and neoplasm localized to one lobe in one. Postoperatively 18 vascular studies identified hepatic arterial compromise in nine, postbiopsy arteriovenous fistula in two, and bleeding from a right adrenal artery in one. Postoperative venography showed thrombosis or occlusion of the IVC in five, portal vein thrombosis in one, and splenic vein thrombosis in one. Of the 18 postoperative angiograms, 12 demonstrated findings considered threatening to the transplants' survival. Six of 18 studies demonstrated findings considered compromising to the transplant. Of the nine postoperative cholangiographic studies, six diagnoses were considered threatening to transplant survival: obstruction of the biliary-enteric anastomosis in four, leakage from the biliary-enteric anastomosis in one, and an abscess from biliary leakage in one.

Adolescent↗