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Biomedical subjects

K Amplatz

Publications and source records attributed to K Amplatz.

At least 163 records · Page 9Linked to original sources
PubMed1984

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↗
PubMed1983

Directional ST-segment deviation in graded exercise tests correlated with motion of the individual segments of the left ventricular wall.

An exercise test may be characterized as positive because of the production of either electrocardiographic ST-segment depression or elevation. The relationship of exercise-induced ST-segment deviation to the specific motion abnormalities of the individual segments of the left ventricular wall was investigated. The first 280 subjects to enter the Program of Surgical Control of Hyperlipidemia were studied by treadmill exercise testing and left ventriculography. The results showed that exercise-induced ST-segment elevation could occur without evidence in the resting subject of either dyskinesia or aneurysm of the left ventricle, that the area of left ventricular damage was much greater in subjects with exercise-induced ST-segment elevation than in those with ST-segment depression, and that wall motion abnormalities were concentrated in the inferoposterior area in the group with ST-segment elevation, but were generally scattered throughout the left ventricular wall in the group with ST-segment depression.

Adult↗
PubMed1983

Percutaneous nephrolithotomy. An approach to branched and staghorn renal calculi.

Using electrohydraulic lithotripsy, we removed branched or staghorn calculi from four patients via a percutaneous nephrostomy tract with local anesthesia. There were no serious complications, and the patients were able to resume their preadmission activities immediately after discharge from the hospital. Our experience suggests that, eventually, all upper urinary tract calculi may be treatable by a percutaneous approach.

Adult↗
PubMed1983

Vessel wall arachidonate metabolism after angioplasty: possible mediators of postangioplasty vasospasm.

The mechanism of postangioplasty vasospasm is uncertain. It was postulated that a reduction in vasodilator prostaglandin I2 (PGI2) or prostaglandin E2 (PGE2) or an increase in vasoconstrictor hydroperoxy acids might contribute to spasm of a dilated artery. Twelve mongrel dogs were anesthetized, intubated, and mechanically ventilated. Heart rate and aortic pressures were continuously monitored and arterial blood gases maintained within physiologic limits. A single carotid artery was dilated in each animal (4 atm X 1 minute X 3) using nonexpandable polyethylene balloon catheters with inflated balloon diameters 50 to 100% larger than the internal arterial lumen. The opposite carotid artery served as a control. In 4 animals, aspirin (10 mg/kg, intravenously) was injected 30 minutes before dilation. Sixty minutes after dilation, animals were heparinized and the carotid arteries carefully removed. The in vitro conversion of carbon-14(14C)-arachidonic acid (AA) to 6-keto PGF1 alpha (PGI2), PGE2, and 12L-hydroxy-5,8,10,14-eicosatetraenoic acid (HETE) was determined using thin-layer radiochromatography. Angioplasty caused a 70% decrease in vessel wall PGI2 production and a 44% decrease in PGE2 production (n = 4, p less than 0.05). Reductions in in vitro conversion of 14C-AA to PGI2 and PGE2 induced by angioplasty were comparable to that produced by cyclooxygenase inhibition with aspirin. Angioplasty, in addition, caused a 104% increase in vessel wall HETE production (n = 4, p less than 0.05). Therefore, angioplasty results in a local derangement of AA metabolism characterized by decreases in vasodilator prostaglandins and increases in vasoconstrictor hydroperoxy acids. These local changes may contribute, in part, to sudden arterial occlusion after angioplasty.

5,8,11,14-Eicosatetraynoic Acid↗
PubMed1983

Maximal postextrasystolic potentiation following multiple extrasystoles: a simple means of myocardial assessment.

To obtain consistent, reproducible postextrasystolic potentiation (PESP), a single closely coupled extrasystole (ES) must be introduced using transvenous pacing. We hypothesized that multiple ES (spontaneous or catheter induced) produce maximal PESP at all coupling intervals (CI). Differences in PESP between single and double ES were assessed in dogs at varying CI by two different methods [systolic time intervals--PEP/LVET, and endocardial markers--ejection fraction (EF)]. Single ES produced variable decreases in PEP/LVET (-8.6 +/- 2.7% (SE) to -22.9 +/- 4.0%) depending on the CI duration. Double ES produced maximal decreases (-26.0 +/- 1.2%) at all CI. A similar relationship was noted for EF following single ES (8.6 +/- 2.7% to 43.0 +/- 4.0%) and double ES (42.9 +/- 1.3%). Double ES produced maximal PESP at all CI. This finding may allow simple myocardial assessment during routine left ventricular catheterization without simultaneous right ventricular catheterization.

Animals↗
PubMed1983

Clinical angiographic regression of atherosclerosis after partial ileal bypass.

Clinical documentation of atherosclerotic plaque regression has been difficult to obtain. This is a report of a patient with severe and early atherosclerotic cardiovascular disease with regression of at least three major atherosclerotic lesions demonstrated by coronary arteriography 10 years after partial ileal bypass operation. The patient's total plasma cholesterol was reduced over these 10 years, ranging from 40% to 23%, from the preoperative level of 757 mg/dl. Sequential arteriograms were assessed independently by several arteriographers and blindly by the Arteriography Review Panel of the Program on Surgical Control of the Hyperlipidemias (POSCH). The readings were analyzed by 4 grading methods. Unanimously, marked regression was read in the proximal left circumflex artery (70% leads to 20%), middle segment of the right coronary artery (45% leads to 20%), and in the distal right coronary artery (80% leads to 50%). Thus, by any and all of the methods used, there was significant regression of arteriographically demonstrated atherosclerotic lesions.

Adult↗
PubMed1983

Hydralazine and the tourniquet test in renal vein renin sampling: a comparison.

A total of 36 salt-depleted patients with suspected renovascular hypertension received intravenous hydralazine and 36 were subjected to the tourniquet test at the time of renal vein renin sampling. Simultaneous bilateral renal vein samples were obtained sequentially over 30 minutes. Both measures resulted in an increase in renin secretion. The number of patients showing a positive ratio (greater than or equal to 1.5) between the angiographically abnormal kidney and the contralateral kidney increased in both groups. In the hydralazine group, 47% had positive ratios at 0 min compared with 80% following hydralazine administration. In the tourniquet group, 53% had positive ratios at 0 min compared with 78% afterward. In neither group did all patients have positive ratios throughout the entire sampling period. Hydralazine produced a greater increase in renin, but more variable results. It is concluded that salt depletion is inadequate for detection of a pressor kidney, and an additional stress is required. Multiple simultaneous samples should be obtained.

Blood Pressure↗
PubMed1983

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↗
PubMed1983

Rapid balloon dilatation of the nephrostomy track for nephrostolithotomy.

The Olbert balloon catheter can be used to dilate a nephrostomy track from 9 to 30 F (3 to 10 mm) in a single step. Percutaneous nephrostomy, track dilatation, and percutaneous stone extraction can be performed within 40 to 90 minutes. The authors have used this catheter successfully in 10 patients without encountering complications.

Catheterization↗
PubMed1983

The vasa vasorum and angioplasty.

Interruption of flow in the vasa vasorum may lead to medial necrosis and aneurysm formation. The purpose of this study was to determine whether angioplasty produces significant alterations in the morphology or blood flow of the vasa vasorum of the dilated artery. The morphology of the canine vasa vasorum was studied before and after angioplasty; in a separate experiment vessel wall blood flow (VWBF) in canine carotid arteries was measured after angioplasty to determine whether physiologic regulation of the blood flow was disrupted by arterial dilation. No morphologic changes could be demonstrated in the vasa vasorum of the dilated artery; however, VWBF was increased by 1194 +/- 215% (mean +/- standard error, p less than 0.01) between 90 and 120 minutes after angioplasty. VWBF in the adjacent nondilated arterial segment was also increased (720 +/- 177% between 10-30 minutes, p less than 0.01) but returned toward normal after 60 minutes. Adenosine caused a "paradoxical" decrease in VWBF (p less than 0.05) of the dilated arterial segment while causing increased VWBF (p less than 0.05) in the thoracic aorta. Angioplasty appears to produce persistent hyperemia in the dilated arterial wall. A paradoxical response to adenosine suggests that vasa vasorum in the dilated arterial segment are maximally vasodilated. This may be due to mechanical disruption of vasomotor tone or to release of vasoactive substances.

Adenosine↗
PubMed1983

Spermatic vein obliteration using hot contrast medium in dogs.

Obliteration of varicoceles in men with infertility has been shown to improve semen quality and increase fertility rates. Many current techniques involve complex procedures and specialized equipment and may be associated with adverse effects. Transcatheter thermal vessel occlusion was utilized for spermatic vein obliteration in dogs. Diatrizoate (76%) contrast medium at a temperature of 100 degrees C was injected into canine spermatic veins. Follow-up venography and histologic examination revealed thrombosis of the injected veins without damage to the surrounding tissues in all cases. Clinical and laboratory examination of the animals revealed no adverse systemic effects. It is concluded that transcatheter thermal venous occlusion is an effective technique for spermatic vein occlusion in a canine model.

Animals↗
PubMed1983

Percutaneous techniques in the management of urological complications in renal transplant patients.

Obstruction of urine flow and urine leaks are potentially life-threatening complications in renal transplant patients. The diagnosis is difficult, and definite treatment may therefore be delayed. This paper reviews the clinical course of ten renal transplant patients with urologic complications, discusses the limitations of the standard tests used to investigate such problems, and describes the role of percutaneous antegrade pyelography and nephrostomy drainage catheter placement as safe and accurate diagnostic and therapeutic procedures.

Adolescent↗
PubMed1983

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↗
PubMed1983

Renal ablation using hot contrast medium: an experimental study. Work in progress.

Ablation of the kidney was attempted in 12 dogs by injecting 10-30 ml of heated (100 degrees C) contrast medium (Hypaque-60, diatrizoate meglumine) into the renal artery. Complete renal ablation without collateralization was demonstrated. Hot contrast medium is an effective embolic agent, and its use is associated with few of the drawbacks of presently used techniques.

Angiography↗
PubMed1983

Failing or thrombosed Brescia-Cimino arteriovenous dialysis fistulas. Angiographic evaluation and percutaneous transluminal angioplasty.

Surgically created arteriovenous fistulas of the Brescia-Cimino type are commonly used for dialysis. When they fail, it can be a very difficult and time-consuming problem to manage surgically. The authors describe a simple method of evaluating and treating failing Brescia-Cimino fistulas in outpatients, involving a combination of cinefistulography, pressure measurements, and balloon angioplasty.

Adult↗
PubMed1983

Work in progress: transcatheter embolization with cyanoacrylate and nitrocellulose.

The authors describe a modified form of isobutyl-2-cyanoacrylate (IBCA) which has been mixed with less than or equal to 4% w/w of nitrocellulose. Transcatheter embolization was carried out in rabbits and dogs without complications. The glue was readily injectable without balloon catheters. Because of its delayed polymerization, it was carried into smaller peripheral arterial branches by the bloodstream, resulting in complete organ ablation without development of collateral circulation. Other advantages of the modified compound include improved plasticity, adherence to not only ionic but also dry non-ionic surfaces, and the ability to control the duration of polymerization.

Animals↗
PubMed1983

Prostaglandins and angioplasty. An experimental study in canine arteries.

To prevent platelet aggregation following percutaneous transluminal angioplasty (PTA), cyclooxygenase inhibitors such as acetylsalicylic acid (ASA) and indomethacin are recommended. However, ASA blocks both the proaggregating effects of thromboxane (TXA2) and the antiaggregating and vasodilating effects of prostacyclin (PGI2). The authors measured the contractile response of dilated canine carotid arteries in situ and in vitro using an isometric force transducer. Following PTA, contraction of the arterial wall was significantly reduced (p less than 0.01). By blocking cyclooxygenase with indomethacin (3 micrograms/ml), contraction was greatly improved (p less than 0.001). These results suggest that PTA may result in marked release of prostacyclin by the damaged arterial wall, which could account for the decreased responsiveness of the artery to exogenous norepinephrine.

Angioplasty, Balloon↗