Wilfrido R. Castaneda-Zuniga

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.

Balloon dilation angioplasty of hypoplastic and stenotic pulmonary arteries.

Balloon dilation angioplasty (BDA) was attempted in seven children with either stenosis or hypoplasia (a narrowing greater than 1 cm long extending past the lung hilum) of both right and left pulmonary arteries (PAs). In two of these seven, the procedure could not be performed because of technical difficulties. In each of the remaining five children (1½–16 years old), the right ventricular (RV) pressure was greater than ⅔ left ventricular pressure, main PA pressure was greater than 60 mm Hg, and previous operative attempts to relieve RVoutflow obstruction, including the branch PA obstruction, were unsuccessful. BDA was performed in only one PA in each patient, and was considered successful if the pressure gradient decreased, angiographic diameter increased and the percentage of blood flow directed to the dilated lung increased. BDA was successful in all five children: RV pressure fell from 104 + 42 to 80 ± 30 mm Hg (p < 0.05), the gradient across the obstruction fell from 61 ± 51 to 32 22 mm Hg (p < 0.05), the diameter of the narrowed segment increased from 3.7 ± 1.2 to 6.8 ± 1.1 mm, p = 0.02), and the percentage of blood flow (as determined by quantitative lung scan) to the dilated lung increased from 41 16% to 52 ± 22% (p < 0.05). No morbidity was observed in any patient. Follow-up angiograms (2–12 months) in three of five patients indicate persistence of the anatomic improvement. While BDA did not restore right-heart pressures and anatomy to normal, it provided significant hemodynamic relief to a group of patients in whom traditional operative management has usually been unsuccessful. Final determination of the role of BDA in such patients must await the results of further studies.

Percutaneous Nephrolithotomy: Extraction of Renal and Ureteral Calculi from 100 Patients

A percutaneous nephrostomy tract was used as a conduit to the kidney and ureter for extraction of 149 calculi in 100 patients. A variety of grasping and fragmentation techniques under fluoroscopic and endoscopic control were used to extract calculi in 88 per cent of the patients. With experience, operator efficiency and rate of stone extraction increased from 76 per cent early in the series to 91 per cent in the most recent patients, and the incidence of complications decreased from 17 to 5 per cent. Percutaneous removal of upper tract urinary calculi appears to be an appropriate alternative to an open operation in most patients with symptomatic urolithiasis.

Transcutaneous angioplasty of experimental aortic coarctation.

A dilatable form of juxtaductal aortic coarctation was surgically created in 29 newborn lambs. Of the 17 long‐term survivors, four lambs served as controls and 13 underwent transcutaneous balloon dilation angioplasty with either polyvinylchloride or polyethylene catheters after 7‐10 weeks of recovery. During growth before dilation, there was little change in the systolic gradient across the coarctation (36.6‐35.3 mm Hg) despite an increase in animal weight from 3.8 to 19.3 kg. This systolic gradient remained constant in undilated lambs throughout a 6-month follow-up. Dilation produced an immediate 65% increase in the diameter of the coarctation and a 68% decrease in the systolic gradient across the coarctation site. Successful dilation required very high (6-8 atmospheres) dilating pressures. This gradient relief persisted throughout a follow-up of up to 1 year. Although no late sequelae could be attributed to the ngioplasty, one lamb suffered an anterior aortic tear limits and optimal protocols for dilating human coarctations are not known.

THE FORGOTTEN INDWELLING URETERAL STENT: A UROLOGICAL DILEMMA

Ureteral stents are an integral part of urological practice. However, stents that migrate, fragment or are forgotten pose a management and legal dilemma. Our series consists of 31 patients, 22 with forgotten stents that were left indwelling for more than 6 months (mean 22.7) and 9 migrated stents. Of the forgotten stents 15 (68%) were calcified, 10 (45%) were fragmented, and 3 (14%) were calcified and fragmented. Procedures to render the patient stent-free were ureteroscopy in 16 (52%), percutaneous nephroscopy in 8 (26%), cystoscopic electrohydraulic lithotripsy in 6 (19%), extracorporeal shock wave lithotripsy in 10 (32%), open cysto-litholapaxy in 1 (3%) and simple nephrectomy in 1 (3%). Multiple procedures were required in 6 patients (19%). Management of such complicated ureteral stents requires a multimodal therapeutic approach incorporating the latest in extracorporeal shock wave lithotripsy and endourological techniques. These patients are at increased risk for loss of renal function. A computerized tracking registry of ureteral stents may help prevent this urological travesty.

Results of a multicenter study of the modified hook-titanium Greenfield filter

Initial efforts to modify the stainless steel Greenfield filter for percutaneous insertion led to development of a titanium Greenfield filter, which could be inserted by use of a 12F carrier. This device functioned well as a filter but had an unacceptable 30% rate of migration, tilting, and penetration. Therefore a titanium Greenfield filter with modified hooks was developed and has been tested in 186 patients at 10 institutions. Successful placement occurred in 181 (97%); placement of the remainder was precluded by unfavorable anatomy. A contraindication to anticoagulation was the most frequent indication for insertion (75%). All but two were inserted percutaneously, predominantly via the right femoral vein (70%). Initial incomplete opening was seen in four patients (2%), which was corrected by guide wire manipulation and asymmetry of the legs in 10 (5.4%). Insertion site hematoma occurred in one patient, and apical penetration of the cava during insertion occurred in a second patient. Both events were without sequelae. Follow-up examinations were performed at 30 days at which time 35 deaths had occurred. Recurrent embolism was suspected in six patients (3%) and two of three deaths were confirmed by autopsy. Filter movement greater than 9 mm was seen in 13 patients, (11%) and increase in base diameter greater than or equal to 5 mm was seen in 17 patients (14%). CT scanning showed evidence of caval penetration in only one patient (0.8%). Insertion site venous thrombosis was seen in 4/46 (8.7%) patients screened. The modified hook titanium Greenfield filter is inserted percutaneously or operatively through a sheath, eliminating concern for misplacement from premature discharge.(ABSTRACT TRUNCATED AT 250 WORDS)

Use of gianturco self-expandable stents in the tracheobronchial tree

Gianturco self-expandable stents were used successfully in the management of 5 patients with tracheobronchial pathology. Placement was performed under endoscopic and fluoroscopic guidance. None of the patients has experienced complications secondary to the stent placement, and in all of them the clinical problems resolved satisfactorily. Longer follow-up is required to determine the place of tracheobronchial stenting in patients with respiratory compromise.

Initial Clinical Experience with Colonic Stent Placement

BACKGROUND The purpose of this study is to review initial experience with a colonic stent as an alternative to colostomy in patients with colonic obstruction. METHODS Ten patients diagnosed with acute colonic obstructions from both benign and malignant causes underwent stent placement. Self-expandable metallic stents were deployed using fluoroscopic guidance. Patients were followed up clinically until removal of the stent or death. RESULTS Nine of the 10 patients who underwent colonic stent placement achieved clinical decompression within 6 hours. Six patients underwent standard mechanical bowel preparation and elective resection of obstructing lesions. The other 4 patients received stent placement for palliative purposes. Complications included 4 cases of migration and 1 death. Migrated stents in the rectum were easily retrieved and replaced using fluoroscopic techniques. There were no perforations. CONCLUSION Placement of self-expandable metallic stents for acute colonic obstructions may allow patients to undergo elective surgical resection avoiding possible colostomy.

Experimental Observations on Short and Long-Term Effects of Arterial Occlusion with Ivalon

Ivalon sponge has proved to be a useful embolic material, particularly when long-term or permanent occlusions are desirable. It has been stated that Ivalon is well tolerated and that it produces little if any damage to the wall or periadventitial tissues of the embolized artery. Our study demonstrates definite evidence of inflammatory reaction in the wall of the embolized arteries; these changes were seen only in the acute phase and seem to be secondary to damage of the vessel wall by the plastic material. Permanent occlusion results with disappearance of the inflammatory changes at nine months postembolization.

Transplant Renal Artery Stenosis: Evaluation with Duplex Sonography

Determination of the cause of hypertension in renal transplant recipients has required invasive studies such as angiography. Consequently there has been recent interest in noninvasive evaluation. Over a 19-month period, duplex sonography was performed on the renal transplant vasculature in 31 allograft recipients who also underwent correlative arteriography. One patient underwent a repeat duplex study and arteriography after surgical repair. On the basis that a frequency shift greater than 7.5 kHz and associated distal turbulence indicate stenosis, 18 duplex sonographic studies were considered positive. Subsequent angiography showed renal artery stenosis in 16 patients and no significant lesion in two. In 14 patients Doppler studies were interpreted as normal; angiography showed no significant arterial abnormality in 13 and significant stenosis in one. These results indicate a sensitivity of 94.1% and specificity of 86.7% for duplex sonography in the diagnosis of transplant renal artery stenosis. Duplex sonography appears to be an excellent noninvasive screening method to evaluate arterial stenosis following renal transplantation.