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Biomedical subjects

K Amplatz

Publications and source records attributed to K Amplatz.

At least 181 records · Page 10Linked to original sources
PubMed1983

Balloon dilation angioplasty of aortic coarctations in infants and children.

Balloon dilation angioplasty (BDA) was attempted nine times in eight infants and children with aortic coarctation. In three infants (all with associated ventricular septal defect or atrioventricular canal and marked hemodynamic instability) dilation was attempted at a site of aortic narrowing that had not been operated on previously. Although the coarctation gradient fell 40% or more over the short term in two of the three, there was no angiographic or late gradient evidence of improvement. All three underwent subsequent coarctation surgery. Five dilations were performed in four infants and children who had previously undergone coarctation surgery (end-to-end anastomosis, attempted jump graft, and subclavian flap) and had residual gradients. Dilation was successful in all five cases, resulting in an increase in the diameter at the coarctation site (4.7 +/- 2.6 to 7.7 +/- 4.0 mm, p less than .05) and a decrease in the gradient measured 24 hr after dilation (42.0 +/- 15.5 to 11.8 +/- 11.2 mm Hg, p less than .05). In one child with a long area of hypoplasia of the thoracic aorta and similar lesions of the brachiocephalic vessels, a preliminary attempt to dilate a severely narrowed subclavian artery was unsuccessful. Postdilation angiography demonstrated evidence of intimal tears in three of five successful dilations. Follow-up (1 to 6 months) has demonstrated continued gradient relief in four of five children. BDA is frequently, but not always, a successful treatment for human aortic coarctation. The chief determinant of success appears to be the nature of the lesion; short-term changes in coarctation gradient are unreliable indicators of success of failure. Although BDA was not associated with mortality or significant morbidity in this group of patients, its role in the management of children with coarctation is yet to be determined.

Adolescent↗
PubMed1983

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↗
PubMed1983

Effect of aspirin on angioplasty-induced vessel wall hyperemia.

Angioplasty produces a persistent 20-fold increase in blood flow through mural vasa vasorum. To assess the role of prostaglandins in this phenomenon, vessel wall blood flow in experimentally dilated carotid arteries of aspirin treated dogs was measured. Aspirin (10 mg/kg, intravenously) significantly attenuated the increase in blood flow produced by dilation (+283 +/- 91% SE, n = 6) when compared to non-aspirin-treated controls (+2356 +/- 885% SE, n = 10). This suggests that aspirin, by interfering with arachidonate metabolism, may decrease local vasodilation after angioplasty. The effect of aspirin therapy on the long-term success of angioplasty requires further study.

Angioplasty, Balloon↗
PubMed1983

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↗
PubMed1982

Coilon removal.

Explore the source record for details and available documents.

Adult↗
PubMed1982

Three-dimensional teaching model for coronary angiography.

In order to improve the understanding and interpretation of cine coronary arteriograms obtained in various angled projections, a three-dimensional wire model was constructed. The main coronary arteries and most important muscular branches are simulated by a wire skeleton. The model can be rotated to simulate the standard right and left anterior oblique and left lateral projections. The degree of rotation is indicated on the base of the model. By tilting the model, cephalad and caudad tube angulation can be simulated. By placing the model in front of the cine projector, the shadows of the wires can be superimposed upon the projected cine coronary arteriogram. This simple, inexpensive model has greatly improved the three-dimensional understanding of the coronary arterial tree in various angled and nonangled views and in our practice had led to the development of additional useful projections.

Angiography↗
PubMed1982

Percutaneous circle-tube nephroureterostomy.

A method for placement of a circle nephroureterostomy tube in patients with cutaneous ureterostomies is described. The technique requires local anesthesia only and, because the 16F tubes become incrusted less often in these patients than do ureteral stents, the tubes need to be changed only every 3 to 6 months.

Fistula↗
PubMed1982

Tardokinesia: definition and clinical occurrence.

Tardokinesia is an abnormal slowness of contraction of a region of the left ventricular (LV) wall. This concept was stated in quantitative terms and used for analyzing LV regional wall motion. Forty-four consecutive patients from the case stream of the Cardiovascular Radiology Service were chosen, and their cine left ventriculograms were studied. A polar grid of thirty radii, at twelve degree increments, was superimposed on the tracing of each ventricle. The wall motion was measured at thirty points, and the location, speed, and acceleration of each point in each cine was calculated. Two cases of tardokinesia were found. Tardokinesia might be a sensitive or early indicator of ischemic heart disease.

Adult↗
PubMed1982

The mechanism of angioplasty. Dilatation of iliac cadaver arteries with intravascular pressure control.

A model was developed which allows the dilatation of iliac cadaver arteries under normal blood pressure conditions (mean pressure 100 mmHg). Segments of the iliac artery were put under pressure and dilated with balloons under similar conditions as in clinical practice. Purposely oversized balloons were used because most of the arteries did not contain severely stenotic plaques and consequently the commercially available balloons had no effect because of their comparatively small diameter. In spite of the use of oversized balloons, the cadaver arteries could not be significant dilated. Rupture of the intima and media was almost invariably present. Leakage of distending fluid through the adventitia occurred commonly. The "therapeutic range" between minimal dilation and partial or total rupture in postmortem studies is small.

Adolescent↗
PubMed1982

Sources of artifacts in rotational scanography.

The images produced in rotational scanography, currently under investigation at several institutions, may contain several kinds of artifacts. The sources of such artifacts are: 1. vertical and horizontal misalignment of the focal spot with the axis of rotation; 2 misalignment of the primary and secondary slits; 3 a density gradient due to slit cut-off; 4 vibration of the x-ray tube during rotation; 5. A density gradient due to variation in motor speed; 6. radiographic striations due to ripple of the tube output. Striations are present even if a 12-pulse generator is used, but they disappear if a constant potential generator is employed.

Humans↗
PubMed1982

The significance of efficient scatter removal in chest radiography.

The conventional approach to the removal of secondary radiation in chest radiography is by using an air gap or a radiographic grid. However, grids become ineffective at high kVp levels. This study evaluated efficient scatter removal by radiographic scanography versus the conventional technique. Nylon spheres simulating lung nodules were attached to a standard radiographic thorax phantom and to a special chest phantom of our own design. Conventional and scanographic films were made of the phantoms using the same conditions. The films were read in a double-blind fashion. The results indicated that scanograms permitted appreciation of the simulated nodules over the lungs better than did the conventional films, particularly at higher kVp levels. However, the marked increase of contrast resulted in an underpenetration of the mediastinum. If properly penetrated, the lung fields were overexposed, which resulted in a decrease of the detectability of lesions in spite of a higher normalized contrast. Scanography is a promising technique for improving the detection rate of lung nodules on chest films, provided that means can be found to penetrate the mediastinum without overexposing the lungs.

Humans↗
PubMed1982

Balloon dilatation of excised aortic coarctations.

Seven children 1-6 years of age underwent aortic resection and re-anastomosis for coarctation of the thoracic aorta. The excised segments were 1-2 cm long and were dilated in vitro with a Grüntzig balloon catheter less than two hours after resection. A pressure of 4-8 atmospheres was used, and the inflated diameter of the balloon was twice the luminal diameter of the undilated coarctation. The diameter of each specimen was increased by an average of 85%, largely because of an increase in the external diameter of the coarctation. However, extremely high pressures were required for successful dilatation, producing transmedial tears in the "normal" aorta distal to the coarctation in three specimens. These results indicate that although balloon dilatation appears feasible as palliation for aortic coarctation, further studies of its safety are necessary before instituting clinical trials.

Angioplasty, Balloon↗
PubMed1982

Transluminal dilatation of coarctation of the abdominal aorta. An experimental study in dogs.

The optimal treatment for recurrent coarctation of the aorta remains undefined. Recurrent stenosis following surgical repair occurs in 6-48% of cases involving the thoracic aorta. Because of the high morbidity and mortality associated with surgery, an alternate approach such as transluminal angioplasty is desirable. To evaluate this possibility, the authors created several experimental lesions to test their capability for dilatation, using the percutaneous transluminal technique. The results indicate that balloon dilatation of coarctation after end-to-end anastomosis is difficult or impossible. Dilatation of other types of suture lines may also be difficult due to the large amount of fibrous tissue at the anastomotic site, which is not amenable to balloon dilatation. Thus surgery remains the preferred form of therapy.

Angioplasty, Balloon↗