Nephrotoxicity from contrast material in renal insufficiency: ionic versus nonionic agents

Controversy exists over whether use of low-osmolality contrast agents is of any benefit in mitigating the risk of contrast material-induced nephrotoxicity (CN) in patients with impaired renal function. To test this hypothesis, 101 adult inpatients with high serum creatinine levels (range, 1.4-2.4 mg/dL [120-210 mumol/L]) undergoing contrast material-enhanced computed tomography were randomized to receive ionic or nonionic (low-osmolality) contrast agents in a uniform dose. Changes in serum creatinine level at 48 hours were measured. Seven (14%) of the 50 patients receiving ionic contrast media experienced an increase of 25% or more in serum creatinine level. Only one (2%) of the 51 patients receiving nonionic contrast agents experienced such an increase, a statistically significant difference (P less than .05). In the subset of 25 diabetic patients, the difference was of a similar magnitude. These data suggest that ionic contrast media are more likely than nonionic contrast agents to cause mild exacerbation of renal insufficiency when given intravenously. However, there were no cases of clinically important CN in the study.

Hematoma formation after diagnostic angiography: effect of catheter size

The authors studied the effect of catheter size on the development of hematomas after catheterization. Four hundred ninety-nine patients who underwent routine diagnostic angiography were randomized to receive either 5-F or 7-F catheters. Small hematomas were more frequent in the 7-F catheter group (P less than .05); however, there was no difference in the frequency of larger hematomas between groups. Compression time was slightly but significantly (P less than .001) longer in the 7-F group. When catheter size; duration of the procedure; and patient age, weight, blood pressure and coagulation status were considered as independent variables, patient weight was the most accurate predictor of hematoma formation. The authors conclude that catheter size does not affect the development of a clinically significant hematoma after diagnostic angiography and that other factors such as patient weight are more important in this regard.

Two urokinase dose regimens in native arterial and graft occlusions: initial results of a prospective, randomized clinical trial

The effects of two urokinase (UK) dose regimens on lysis time, lytic success, primary clinical success, and frequency of complications of peripheral thrombolysis were compared. Seventy-two intraarterial UK infusions were performed by means of standard catheter-directed infusion techniques in 63 patients with symptomatic peripheral arterial or bypass graft occlusions. Patients were prospectively randomized to high-dose (250,000 U/h for 4 hours and then 125,000 U/h) or low-dose (50,000 U/h) regimens. The mean time to complete lysis was 20.8, 26.0, 16.5, and 18.2 hours for the high-dose artery, low-dose artery, high-dose graft, and low-dose graft groups, respectively (P was not significant). Respective mean infusion durations were 27.1, 35.4, 22.2, and 25.3 hours. Clinical success was achieved in 65%-85% of cases. The frequency of complications was equivalent between groups, except for a higher frequency of minor bleeding complications in the high-dose group. The two urokinase dose regimens studied were equally effective in enabling peripheral thrombolysis.

Peripheral atherectomy: experimental results with a new device

The size of present rotational atherectomy devices is limited in part by a tendency to produce vessel torsion. The authors designed and investigated a large-bore rotational atherectomy device for peripheral atherectomy in a single pass without significant torsion. A plaque was retrieved from 36 of 40 cadaveric iliac arteries. The mean plaque size was 8.4 x 3.9 mm, and the average number retrieved per artery was two. Thirty of 34 severely calcified arteries were treated successfully. Effluent study revealed no distal embolization; however, six perforations and four dissections occurred. Preliminary results suggest that a cutting surface with a relatively large diameter can be designed to be effective without producing vessel torsion. Changes in future designs will include added flexibility and expandable cutting surfaces to enhance safety and minimize entry diameter.

Thermal balloon angioplasty in a canine model: preliminary results

Preliminary results suggest that thermal balloon angioplasty (BA) may produce plaque welding, decreased elastic recoil, and increased luminal caliber. The authors report results of a simple method of thermal BA in a canine model. Seven mongrel dogs (15-25 kg) underwent conventional BA of each iliac artery with balloons that were 1-2 mm larger than the vessel lumen. The balloons were then perfused with a mixture of saline and contrast material at either 25 degrees C (control) or 100 degrees C for 1 minute. Compared with baseline measurements, thermal BA produced greater lumen enlargement (+16.7%) than control BA (+3.4%) immediately after the procedure (P less than .05). This trend persisted in vessels studied after a delay of 2, 4, or 12 weeks. Histologic sections from specimens studied after a delay demonstrated intimal hyperplasia in both the thermally treated and control arteries. Medial sclerosis was consistently seen in the thermally treated arteries. The authors conclude that thermal BA results in immediate and delayed increases in arterial diameter compared with conventional BA due to decreased elastic recoil and medial sclerosis.

Plaque modification with tetracycline: enhanced tissue ablation with the excimer laser

Tetracycline has been shown to collect selectively in atherosclerotic plaque and is a known photosensitizing agent. To determine if tetracycline enhances the photoablative effects of the ultraviolet xenon-fluorine excimer laser, the authors exposed four cadaveric aortic samples to tetracycline and four to only normal saline. Ninety-three sites in the samples were subjected to laser energy and analyzed with light microscopy for crater depth and width and for degree of thermal injury. Forty-three of the sites were histologically normal, and 50 were atherosclerotic. Crater depth did not differ significantly in atherosclerotic and normal sites not exposed to tetracycline. Atherosclerotic sites exposed to tetracycline showed significantly deeper craters compared with those in normal, exposed sites. The effects of tetracycline exposure and histologic characteristics (normal vs atherosclerotic) on crater width and thermal injury were independent and additive. When the excimer laser is used for treatment, tetracycline can definitely enhance atherosclerotic plaque ablation.

New guide wire for high-flow infusion

A new open-ended guide wire with a large internal diameter was compared with two other open-ended guide-wire and catheter infusion systems. Simple experiments were performed to compare flow rates and ability to track. The larger internal diameter of the new wire allowed higher flow rates and accepted an 0.025-inch (0.64-mm) guide wire. The flexibility of the new infusion wire was shown to be equivalent to that of the catheter system. The authors conclude that the new wire has advantages in terms of flow rates and ability to track, compared with presently available infusion systems.

Techniques for lower-limb angiography: a comparative study

Three separate variables--volume of contrast material, site of contrast material injection, and arterial inflow occlusion--were tested in a prospective, randomized fashion in 52 patients to determine the best technique for lower-limb angiography. Twelve patients received 30 and 60 mL of contrast material injected at the level of the external iliac artery (EIA), 20 patients received 60 mL injected at the level of the EIA with and without inflow occlusion, and 20 patients received 120 mL injected at the level of the aortic bifurcation and 60 mL injected at the level of the EIA. A total of 104 angiograms were obtained, two in each patient. Two examiners reviewed all angiograms in a blinded fashion, initially as 104 separate studies for diagnostic adequacy (ie, the need for additional angiography) and then as 52 paired studies for direct comparison of the quality of arterial filling (ie, the best-appearing angiogram). The 60-mL studies were significantly better (P less than .001) in both categories when compared with both the 30- and the 120-mL studies. There was, however, no significant difference between the 60-mL studies with and without inflow occlusion. The authors conclude that the best screen-film lower-limb angiograms are obtained with large volumes (60 mL) of contrast material injected below the pelvic vessels (EIA).

Vascular applications of laser

The authors review the current experimental and clinical literature relating to the use of lasers in peripheral vascular disease. During the past few years, significant strides have been made in effective harnessing of laser energy for percutaneous revascularization. However, the role of lasers in treating vascular disease is not yet clear. Thus current application of laser technology in this area should be considered experimental until adequate clinical studies confirm its efficacy.

Thrombus-trapping efficiency of the Greenfield filter in vivo

A total of 100 radiopaque blood clots were injected into seven adult sheep under fluoroscopic observation to assess the clot-trapping efficiency of the Greenfield vena caval filter. Eleven percent of the clots passed through the filter, with all failures limited to the two smallest clot sizes: 4 x 10 mm (five of 25) and 4 x 30 mm (six of 25). The Greenfield filter was 100% efficient in trapping larger clots (8 x 10 mm and 8 x 30 mm). There was a tendency toward poorer clot-trapping performance when the Greenfield filter was tilted within the vena cava, but this was not significant. There were no significant differences in hemodynamic measurements obtained immediately before and after injection of each clot, and no significant changes were noted in the animal's hemodynamic status or in blood gas measurements in those cases in which the clots passed through the filter. Since the caval diameter in sheep approximates that in humans, the authors conclude that the Greenfield filter in the clinical setting is capable of stopping large, likely fatal, emboli and a large number of smaller, possibly less clinically significant, emboli.

Incidental fibromuscular dysplasia in potential renal donors: long-term clinical follow-up

The clinical natural history of renal arterial fibromuscular dysplasia (FMD) in patients with normal blood pressure is unknown, to the authors' knowledge. The authors reviewed the results of 1,862 renal angiograms obtained in potential renal donors. FMD was present in 71 patients (3.8%). The average age at which FMD was discovered was 50.8 years. Seventy-five percent of the patients with FMD were female. Of 30 patients who did not undergo nephrectomy, eight (26.6%) developed hypertension over a mean followup interval of 7.5 years. Of 19 patients who underwent nephrectomy, despite the presence of FMD, five (26.3%) developed hypertension over a mean follow-up interval of 4.4 years. In comparison, three subjects (6.1%) (from a randomized control group of 49 age- and sex-matched healthy individuals) developed hypertension over a mean follow-up period of 7.1 years. The authors conclude that asymptomatic middle-aged individuals with renal FMD develop hypertension at a rate greater than that of age-matched control subjects with normal blood pressure.

Thrombosed polytetrafluoroethylene hemodialysis fistulas: salvage with combined thrombectomy and angioplasty

Combined thrombectomy and angioplasty was performed for 19 thrombosed polytetrafluoroethylene grafts. Patency for more than 1 week was achieved in 16 of the 19 grafts (84%). The average duration of graft function after angioplasty in all 19 grafts was 7.1 months (range, 0-32.3 months). Eleven of the 19 grafts (58%) were functioning 5 months after the procedure; seven are still functioning. Combined thrombectomy and angioplasty offers a viable alternative to thrombolytic therapy or complete surgical revision.

Political trends in vascular and interventional radiology: a randomized survey

There is a trend in the United States toward the performance of vascular and interventional radiology procedures by nonradiologists. A survey was conducted of 2.069 U.S. radiologists to define better the current status of and gather opinions on the future of vascular and interventional radiology. A total of 715 (35%) completed questionnaires were returned. Cross tabulations among subgroups of respondents were performed to address key issues. The median proportion of time spent in the performance of vascular and interventional radiology was 10%, and 51.5% of the radiologists surveyed were in groups that included a fellowship-trained interventional radiologist. More than half (54.4%) of the radiologists indicated that nonradiologists have expressed interest in performing vascular and interventional techniques. According to 13.4% of the radiologists surveyed, cardiologists performed at least some peripheral angiography or angioplasty. The vast majority of radiologists (96.8%) did not want other specialties to assume vascular and interventional radiology procedures, but 16.8% believed these procedures will eventually be lost to other specialties. The results indicate that vascular and interventional radiology is being infringed on to a relatively large degree by other specialties.

Urinary obstruction in renal transplants: diagnosis by antegrade pyelography and results of percutaneous treatment

We reviewed our experience with 51 renal transplants to evaluate the accuracy of antegrade pyelography as compared with that of sonography and nuclear renography in the diagnosis of transplant obstruction. Also, the results of percutaneous treatment were analyzed in 44 of these patients. Obstruction was clinically suspected in all of the patients (increased serum creatinine levels and decreased urine output). Antegrade pyelography showed obstruction in 44 (86%) of the 51 patients, and nephrostomy drainage catheters were inserted. Sonography showed pyelocaliectasis in all 49 cases in which it was performed; in 42, the pyelocaliectasis was due to obstruction (14% false-positive rate). Nuclear renography showed obstruction in only six (18%) of 33 cases in which it was performed; all six cases proved to be obstructed (0% false-positive rate and 82% false-negative rate). Twenty-two (50%) of the 44 patients treated with nephrostomy drainage were managed successfully without surgical intervention; seven of these 22 required balloon dilation of ureteric strictures in addition to catheter decompression of the collecting system. The average duration of catheterization required for successful percutaneous treatment was 35 days. This experience suggests that antegrade pyelography has a definite role in the workup of patients suspected of having renal transplant obstruction. The percutaneous access permits successful catheter drainage. Compared with antegrade pyelography, sonography is reasonably accurate in determining the presence of urinary obstruction, although false-positive diagnoses are found in a substantial number of patients. Nuclear renography is not, however, a useful indicator of obstruction owing to its high false-negative rate. Percutaneous treatment of urinary obstruction in transplantation patients proves successful in approximately 50% of cases.

Urine leaks after renal transplantation: value of percutaneous pyelography and drainage for diagnosis and treatment

We reviewed our experience with 12 renal transplant patients who had urine leaks to compare the accuracies of sonography and nuclear renography with that of antegrade pyelography in establishing the diagnosis. The leak was proved by surgery in 11 of the 12 cases. We also determined the role of diverting percutaneous nephrostomy drainage in the treatment of such leaks. The diagnosis was established by sonography in eight (67%) of the 12 patients. Nuclear renography, performed in nine patients, showed decreased renal function but showed the leak in only three (33%) of the nine cases. Antegrade pyelography, performed in all 12 patients, showed leakage in 10 (83%). In the other two patients, follow-up nephrostograms done within 24 hr showed leaks near the ureterovesical anastomotic site. Seven of 11 patients who were managed with a combination of percutaneous nephrostomy drainage and surgical reconstruction were treated successfully (i.e., a functioning graft was retained); however, only one patient was managed successfully by percutaneous methods alone. Antegrade pyelography is more accurate than sonography and nuclear renography in the detection of urine leakage after renal transplantation. However, percutaneous nephrostomy drainage appears useful only as an adjunct to surgery for treatment of this complication.

Spermatic vein embolization with hot contrast material: fertility results

Spermatic venography with hot contrast material embolization was undertaken in 81 patients with varicoceles and infertility. Long-term follow-up information was available in 91% of the patients, and there was an overall conception rate of 40.5%. Embolization with hot contrast material was easily performed without special embolization devices and proved to be a safe and effective technique.

Current trends in the management of urinary stones

The treatment of renal and ureteral stones has undergone rapid and major changes over the past ten years. Extracorporeal shockwave lithotripsy has become the most commonly used modality for the treatment of renal and upper ureteral stones. Lower ureteral stones are more commonly being approached by retrograde techniques. Percutaneous nephrolithotomy, medical therapy, and open surgical nephrolithotomy offer viable alternatives in given situations. Presented here is the current application of each of these techniques, both alone and in combination, for the treatment of urinary stones.

Safe splenoportography

The records of 37 patients who had undergone splenoportography, including one group of 12 who were studied before 1976 and a second group of 25 who were studied after 1977, were reviewed. The primary difference was that in the second group, the tract in the spleen was occluded with absorbable gelatin sponge (Gelfoam) plugs as the needle was withdrawn. In addition, there were minor changes in technique, such as changes in the needle puncture angle and entry site. When the new technique was used, there was a significant decrease in the complications traditionally associated with splenoportography. This procedure is safe and deserves to be considered the procedure of choice in patients in whom precise anatomic information is needed preoperatively that cannot be obtained with noninvasive procedures such as ultrasound or magnetic resonance imaging.

A new vena caval filter for percutaneous placement and retrieval: experimental study

A new vena caval filter that can be inserted percutaneously through an angiographic catheter is described. The filter is secured by controlled penetration of the caval wall and is designed for percutaneous retrieval. The filter was easily and safely placed and removed in 11 mongrel dogs, and in an in vitro study, the filter was shown to be highly effective and less dependent than the Greenfield filter on positioning. The authors believe that the filter will be suitable for prophylactic placement in patients at high risk for pulmonary thromboembolic disease.

Obliteration of the gallbladder without formal cholecystectomy. A feasibility study

Obliteration of the gallbladder without formal cholecystectomy was attempted in 36 rabbits, using an open technique for cannulation of the gallbladder during laparotomy. The gallbladder was cannulated, the proximal cystic duct was occluded with cyanoacrylate-nitrocellulose 2% wt/wt, and the gallbladder mucosa was exposed to various sclerosing agents to induce fibrosis. Heated 60% diatrizoate meglumine and absolute alcohol induced a controllable chronic cholecystitis with transmural fibrosis within two weeks, a result not seen with morrhuate sodium or in the control groups. All animals survived without complications, and no instances of common bile duct damage or occlusion was noted. The results reported are promising and indicate the need for further studies of this technique for its efficacy and safety.