Search PubMed⌕ Search

Biomedical subjects

K Amplatz

Publications and source records attributed to K Amplatz.

At least 37 records · Page 2Linked to original sources
PubMed1991

Incomplete opening of LGM (Vena Tech) filters inserted via the transjugular approach.

Over a 12-month period, 216 LGM vena caval filters were placed in 216 patients at four institutions. The transjugular approach was used in 31 of 216 insertions (14%); 185 of 216 filters (86%) were inserted via the femoral route. Incomplete opening of filters was encountered in 13 of 31 transjugular insertions (41%) and none of 185 transfemoral insertions. Delayed spontaneous filter opening occurred in three of 12 cases (25%) of incomplete opening (in which follow-up was available) at 5 minutes, 4 days, and 2 months after insertion. One filter opened completely after catheter manipulations. Several mechanisms explaining this complication are proposed. In its present form, the LGM filter should not be inserted via the jugular route. Since the filtering capabilities of the incompletely opened LGM device have been shown to be diminished in vitro, it may be advisable to place a second filter cephalad to an incompletely opened LGM filter.

Equipment Failure↗
PubMed1991

Spermatic vein occlusion with hot contrast material: angiographic results.

Spermatic vein occlusion by means of selective injection of boiling contrast material into the spermatic vein was attempted in 175 men with symptomatic varicoceles or infertility. Seventy-six patients (43%) returned for follow-up venography. Of 115 veins injected, 96 (83%) were totally occluded on the follow-up venogram obtained at 6 weeks to 2 years after injection. In the latter portion of the study, the technique was changed slightly, with injection of larger volumes of hot contrast material, resulting in a 91% occlusion rate. Each vein that was found patent on the follow-up venogram (19 of 115 [16%]) was assessed radiographically, and results were categorized as grade 1, a complete failure in which there was no change from the presclerotherapy appearance (nine of 19 [47%]); grade 2, a failure in which the treated vein was smaller but patent (five of 19 [26%]); or grade 3, a failure in which the treated vein was occluded with newly developed collateral vessels (five of 19 [26%]). The pretreatment size of the spermatic vein and the quantity of hot contrast material injected were both statistically significant factors in the treatment outcome.

Adolescent↗
PubMed1991

Thrombectomy with the transluminal endarterectomy catheter (TEC) system: experimental study and case report.

The transluminal endarterectomy catheter (TEC) system was employed as a percutaneous rotational mechanical thrombectomy device in 1-week-old thrombi in five dogs (five thrombosed polytetrafluoroethylene grafts and four thrombosed native superficial femoral arteries). Luminal patency was restored in all vessels with no angiographic evidence of significant distal embolization. The TEC catheter was also successfully used for recanalization of the superior vena cava in a patient with superior vena cava syndrome.

Animals↗
PubMed1991

Urokinase-mediated thrombolysis: a dose-response relationship in cats. Work in progress.

A cat model was developed to study thrombolytic agents. The infrarenal aorta was surgically exposed, all side branches were ligated, and both ends of the segment were occluded. After preformed clot was injected into the segment, proximal flow was restored and a distal stenosis was created. Urokinase was infused at rates varying from 4,000 to 250,000 U/h. Amount of remaining clot was quantified every 15 minutes with cine angiography. Pre- and postinfusion measurements of prothrombin time, partial thromboplastin time, thrombin time, and levels of fibrinogen and fibrin degradation products were obtained. A graph of thrombolysis rate versus infusion rate was obtained yielding maximal thrombolytic activity at 126,000 U/h and 90% of maximal activity at an infusion rate of 70,000 U/h. Levels of fibrin degradation products did not change. Prothrombin, partial thromboplastin, and thrombin times increased with increasing infusion rates, leveling off at 100,000 U/h, while fibrinogen levels decreased, with a plateau at 50,000 U/h.

Animals↗
PubMed1991

Angiogenesis after hepatic arterial occlusion in liver transplant patients.

The authors describe 10 liver transplant recipients who developed occlusion of the hepatic artery or aortic conduit. Since all potential collateral arterial supply to the transplant is severed at hepatectomy, hepatic artery occlusion is usually a catastrophic event that necessitates repeat transplantation. Four patients died within 8 weeks of transplantation. The remaining six developed spontaneous arterial liver revascularization. This phenomenon is believed to be an example of neovascularization through angiogenesis. Radiologic studies, particularly duplex sonography and angiography, were helpful in the evaluation of transplant vascular integrity. The tissues of the omentum and the mesentery have known angiogenic ability. The authors postulate that in transplantation techniques in which these tissues are placed close to the transplanted liver (eg, Roux-en-Y choledochojejunostomy), the omental and mesenteric tissues may be the source of neovascularity.

Adult↗
PubMed1991

Nonselective and semiselective catheters for renal artery evaluation: experimental study.

Abdominal aortography is widely used for evaluation of potential renal donors and for patients with renal failure or hypertension in whom a renal artery ostial or polar branch stenosis is suspected. It would be desirable to use a catheter that consistently enables good bilateral renal artery and polar branch visualization without opacification of overlying mesenteric vessels. Existing and newly designed catheters were compared to determine the optimal design necessary for these studies. An in vitro model of the abdominal aorta and its branches was made, and dye dilution densitometry was employed for quantitative evaluation. Semiselective catheters demonstrated significantly increased renal artery opacification with decreased mesenteric opacification in this in vitro model.

Aorta, Abdominal↗
PubMed1991

Nitinol gooseneck snare for removal of foreign bodies: experimental study and clinical evaluation.

The authors describe their use of a new right-angle snare made of nickel-titanium (nitinol) cable for retrieval of foreign bodies and iatrogenically placed devices. The snare loop is at right angles to the cable and comes in five sizes (5, 10, 15, 25, and 35 mm); its radiographic visualization is enhanced by gold-plated tungsten coils. This snare was used to retrieve wire and catheter fragments introduced into the thoracic vasculature of four dogs. Eleven of 13 attempts were successful. Three attempts to retrieve intravascular foreign bodies were successful in two patients; in one of these patients, a 10-mm snare was used to remove a fractured end of a ventriculoatrial shunt tube from the left pulmonary artery. In three other patients, four ureteral stents were successfully removed under fluoroscopic guidance. All retrievals were performed through a vascular sheath and with standard techniques and angiographic equipment. No complications were seen in any of the patients or dogs.

Alloys↗
PubMed1991

Clot-trapper device for transjugular thrombectomy from the inferior vena cava.

The clot-trapper device for transjugular thrombectomy was used in 10 dogs with acute thrombosis and two dogs with chronic thrombosis. In eight of these animals, the clots were trapped with the clot-trapper device, then a mechanical thrombectomy device was used to destroy the clots. In 10 animals, including eight with in vitro thrombi and two with in situ thrombi, thrombi were efficiently trapped with the clot-trapper device. In two animals, pulmonary embolism occurred because of a discrepancy between the diameter of the inferior vena cava and the diameter of the bag opening. After increasing the size of the loop to match the diameter of the inferior vena cava, trapping of all thrombi was possible in both experiments (acute and chronic thrombosis). The clot-trapper device, in conjunction with an embolectomy balloon catheter and/or a mechanical thrombectomy device, facilitates the removal of thrombi from the inferior vena cava and iliac veins.

Animals↗
PubMed1991

Thermal ablation of the gallbladder.

Gallbladder ablation by means of injection of hot contrast medium was attempted in 13 dogs. Room temperature contrast medium was injected into the gallbladders of two additional dogs (controls). After midline laparotomy was performed to expose the gallbladder, temperature probes were placed in the liver adjacent to the gallbladder, and on the surface and in the lumen of the gallbladder. A 7-F catheter with multiple side holes was placed into the gallbladder. The cystic duct was clamped during the procedure. After injection of boiling contrast medium, the mean temperature in the gallbladder lumen was 80 degrees C; in the adjacent liver, 43.5 degrees C; and on the gallbladder surface, 45.8 degrees C. After the procedure, the cystic duct was unclamped, temperature probes and catheter were removed, and the laparotomy was closed in standard fashion. In the hot contrast medium group, one dog each was sacrificed at 2, 4, 8, and 12 weeks, and at 6 months. Six animals were sacrificed at 1 year. The gallbladder was completely ablated in 11 of 13 animals in the hot contrast medium group. One dog was sacrificed at 8 days because of bile leakage, and another was sacrificed at 17 days because of gallbladder rupture. The two control animals were sacrificed at 12 and 13 weeks, and their gallbladders were normal at that time.

Animals↗
PubMed1991

1990 ARRS Executive Council Award. Intravascular sonography in the detection of arteriosclerosis and evaluation of vascular interventional procedures.

The purpose of this study was to evaluate the use of intravascular sonography for the detection of arteriosclerosis and to determine the effects of vascular interventional procedures on the arterial wall. A catheter-based 20-MHz transducer was used. Forty patients were studied. Twelve had clinical evidence of peripheral vascular disease, 13 were healthy renal donors, and 15 underwent vascular interventional procedures. The aorta and the ipsilateral iliac artery were examined in real time under fluoroscopic guidance and the results were compared with angiography. Sonography in eight of the 13 renal donors showed arterial wall abnormalities in the absence of angiographic evidence of disease. Sonography of the 15 patients after angioplasty or atherectomy demonstrated plaque fractures, intramural dissections, or atherectomy grooves. Our experience suggests that intravascular sonography is of value in reducing the use of angiography to monitor progress or complications of vascular interventional procedures.

Adult↗
PubMed1991

[Intravascular echography in interventional vascular radiology].

Intravascular US studies were performed with a 20 MHz rotating transducer mounted on a long flexible shaft in 14 patients undergoing interventional vascular procedures--i.e. percutaneous transluminal angioplasty (PTA), atherectomy with a Simpson device, and Palmaz stent placement. Intravascular US was used immediately before the procedure to assess the lesion characteristics and during and after the procedure to verify its results. In PTA, intravascular US clearly shows the fracture of the plaque, its separation from the medial layer, and the total longitudinal extension of the intimal flaps. Palmaz stents are clearly shown and their correct positioning on the arterial wall is therefore precisely evaluated. After atherectomy, intravascular US shows the changes in wall thickness and identifies the areas where more tissue needs to be removed. Intravascular US appears to be a very promising technique for monitoring and directing revascularization procedures by helping select the correct interventional procedure. The initial limitation of use of intravascular ultrasound catheters to straight arterial segments has been resolved by the development of over-the-wire catheters. Further technical development and clinical research are needed.

Adult↗
PubMed1990

A useful projection for demonstrating the bifurcation of the pulmonary artery.

The demonstration of the pulmonary bifurcation is important in order to exclude pulmonary branch stenoses. The origin of the right and left pulmonary arteries can be demonstrated in the anteroposterior plane if cranial angulation is used. Depending on the course of the left pulmonary artery, the origin of the left pulmonary artery may not be seen in spite of the maximal cranial angulation. On the lateral plane without tube angulation the origin left pulmonary artery is commonly superimposed on the origin of the right pulmonary artery. If maximum caudal angulation is added to the steep left anterior oblique view, not only the left, but also the origin of the right pulmonary artery can be seen.

Constriction, Pathologic↗
PubMed1990

Estimation of left ventricular ejection fraction with healed myocardial infarction by multiple regression analysis of electrocardiographic Minnesota Q-QS codes. POSCH Group.

The cardiac damage caused by a myocardial infarction may be evidenced by abnormal electrocardiographic Q-QS complexes (i.e., Minnesota Q-QS codes) and by impairment of left ventricular function. It has been shown that the level of significance of the Q-QS codes is highly correlated with the extent of left ventricular impairment. This study was directed to quantitating this relationship in subjects with a healed myocardial infarction and expressing it mathematically. Using multiple linear regression analysis, a coefficient value was obtained corresponding to the level of significance of each Q-QS code located in each electrocardiographic cardiac area. The left ventricular ejection fraction was estimated by subtracting the coefficient of the most significant code present in each cardiac area from the constant, which was calculated to be the ejection fraction in the absence of any Q-QS code. The results were reproducible, and there was a good correlation between the estimated and measured ejection fraction.

Adult↗
PubMed1990

The inferior vena cava clip. The percutaneous approach.

Pulmonary embolism in high-risk patients may be minimized by surgical inferior vena cava (IVC) clipping or by the insertion of caval filters. A percutaneous clipping technique was developed that narrows the cava while allowing caval patency. The caval clip is inserted through a percutaneous translumbar approach under fluoroscopic control. Nine dogs underwent percutaneous translumbar caval clip placement without complications. Three of four dogs, followed-up for 5 to 19 weeks by angiography and caval pressure measurements, showed caval patency. This technique eliminates the risks of surgical IVC clip placement and risks from the insertion of intravascular foreign bodies such as filters.

Angiography↗
PubMed1990

Perineal abscess after prostatic urethroplasty with balloon catheter: report of a case.

A 72-year-old patient underwent uneventful prostatic urethroplasty by means of a balloon catheter. The immediate follow-up retrograde urethrogram failed to demonstrate any areas of extravasation and showed a significant increase in prostatic urethral caliber. Three weeks after the patient was discharged, computed tomography demonstrated a large perineal abscess that was attributed to either the prostatic urethroplasty or subsequent Foley catheter manipulations. The abscess was drained percutaneously, and the patient recovered uneventfully. It was concluded that the abscess was a possible isolated complication and that the procedure is warranted in an adequate clinical setting.

Abscess↗
PubMed1990

Thrombogenicity of hydrophilically coated guide wires and catheters.

The thrombogenicities of stainless steel spring guide wires and two hydrophilically coated guide wires were compared. The guide wires were placed in canine femoral arteries for 30 minutes. The guide wires were removed, the thrombi were stripped off, and the clots were weighed. Clot weights obtained with the two hydrophilically coated guide wires were significantly less than those obtained with the stainless steel spring guide wires. The thrombogenicities of hydrophilically coated catheters and noncoated nylon catheters were compared with and without the use of heparin. Carotid arteries, jugular veins, femoral arteries, and femoral veins were used. Catheters were left in place for 45 minutes. The animals were heparinized and killed. The vessels were then removed en bloc with the catheter clamped in place. The vessels were incised, and the clot was removed and weighed. In arterial and venous catheterization, no significant difference in clot deposition was shown between the hydrophilically coated catheters and the noncoated nylon catheters. A striking reduction of thrombogenicity was achieved with heparinization of the catheters in both arteries and veins.

Angiography↗
PubMed1990

Therapeutic embolization: enhanced radiolabeled monitoring.

Radiolabeling of Ivalon (polyvinyl alcohol sponge) particles permits localization of injected particles during embolization through the use of a portable gamma camera and provides a means to prevent potentially fatal complications such as pulmonary embolization. A more efficient technique of labeling Ivalon particles with technetium-99m sulfur colloid was developed. An increase in labeling efficiency allowed more accurate determination of the distribution of injected Ivalon particles. Scanning electron microscopy demonstrated the stability of the Ivalon particles during this new labeling process. Two patients with arteriovenous malformations underwent therapeutic embolization with radiolabeled Ivalon particles; gamma camera imaging of the lesion and chest was performed throughout the procedure.

Adult↗