Biomedical subjects
Publications and source records attributed to W Castaneda-Zuniga.
Renal calculi complicating transplanted kidneys are uncommon but they can be an important cause of deterioration in graft function. We report 2 complicated cases managed by percutaneous nephrostolithotomy.
We have used advanced endourologic techniques in the treatment of an obstructed lower-pole calycocystostomy site. The unusual clinical course that led to this problem and the interventional treatment used are discussed.
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Peliosis in a 13-month-old infant is described. This patient appears to be the youngest reported case. The radiologic diagnosis of peliosis is difficult. The condition may be confused with other more common liver diseases. Peliosis is best assessed angiographically.
Coil embolization of an incompetent spermatic vein of a patient resulted in a complication from the use of a sidehole catheter. Alternative procedures are suggested to avoid the problem.
The development of percutaneous nephrostomy has laid the foundation for a major advance in the treatment of urolithiasis: the percutaneous removal of renal and ureteral calculi (i.e., nephrolithotony). With the use of a variety of instruments, calculi can be either removed intact or, if too large, fragmented in situ and then extracted. The method has wide applicability; more than 90% of all upper urinary tract calculi can be successfully treated. Length of hospitalization and costs are comparable to or less than those for open surgery; however, the period of convalescence is only 2-7 days. Continued advances in fluoroscopic technology and endoscopic instrumentation will enable the urologic surgeon to treat the majority of urinary tract conditions using endourologic techniques.
A percutaneous technique is described for the introduction of Kimray-Greenfield filters into the vena cava through either the internal jugular or femoral approach.
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.
When significant thoracic vascular anomalies occur in children, they may present surgical difficulties making operative management undesirable. The recent development of a new, accurate coil-delivery system has enabled us to embolize 17 vessels in five children by passing Gianturco steel coils coated with thrombogenic Dacron strands through No. 5 or 6F end-hole catheters suitable for infants. Coils of 0.038 inch packed diameter were fed through the catheter lumen by a flexible guidewire emerging as 3, 5, or 8 mm diameter loose coils. Fifteen of 17 vessels were successfully occluded. No complications or errors in placement of coils occurred. Four of five children clearly benefitted from the procedure. One died in spite of partial occlusion. Coil embolization can be performed accurately and safely even in small infants with a high rate of successful occlusion and may prove to be a valuable adjunct to operative management.
Balloon dilation angioplasty was attempted in 10 infants and children with severe congenital or operative "venous" obstructions. In five children the obstructions were "vena caval" and followed repair for transposition of the great vessels (four patients) or orthotopic liver transplantation (one patient). In the four patients with fixed vena caval or baffle obstructions, balloon angioplasty was successful in relieving the obstruction, decreasing the average gradient (16.0 to 4.5 mm Hg), and increasing the average diameter (3.0 to 8.9 mm) of the obstructed site. One child died 1 week later from an unrelated cerebral hemorrhage; the three survivors have had persistent clinical and angiographic improvement. The fifth child had severe systolic narrowing of the superior baffle limb caused by marked tricuspid regurgitation, which ballooned the superior limb of the baffle against the atrial roof. Angioplasty was unsuccessful in relieving this type of obstruction, which resolved with tricuspid valve replacement. Of the five infants with obstructed pulmonary veins, three had congenitally narrowed vessels associated with total anomalous pulmonary venous connection, one had acquired stenosis, and one had postoperative obstruction after repair of a mixed type of total anomalous pulmonary venous connection. Dilation was unsuccessful in all five patients, but for different reasons: in the congenitally narrowed veins, the waist in the balloon could not be eliminated, even with high dilating pressures; in the infant with acquired stenosis, the vein stretched but did not tear at low dilating pressures; and in the postoperative obstruction, angioplasty increased the diameter of the obstruction but did not increase flow to the affected lung.(ABSTRACT TRUNCATED AT 250 WORDS)
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.
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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.
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.
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.
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.
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.
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.