Kenneth P. Moresco

SIR Reporting Standards for the Treatment of Acute Limb Ischemia with Use of Transluminal Removal of Arterial Thrombus

ACUTE limb ischemia is any sudden decrease or worsening in limb perfusion that causes a potential threat to limb viability (1). Acute peripheral arterial occlusion may be caused by in situ thrombosis or embolus. In this article, the term “thrombus” will be used to describe arterial occlusion caused by in situ thrombosis or embolus. Percutaneous or “open” surgical techniques can be used to remove the thrombus. Current percutaneous methods for transluminal removal of thrombus (TRT) include thrombolytic therapy (ie, catheter-directed, pharmacomechanic), percutaneous aspiration thrombectomy (PAT), and percutaneous mechanical thrombectomy (PMT). These methods may be used in combination. Surgical techniques entail an “open” procedure that necessitates an arteriotomy for the removal of thrombus. Of the various TRT methods used to treat acute limb ischemia, catheterdirected thrombolytic therapy with urokinase has been the most widely studied. Catheter-directed thrombolytic therapy has at least three theoretical and practical advantages over surgical thromboembolectomy: less endothelial trauma, angiographic visualization of the underlying lesion(s) and runoff vessels, and, in many cases, ready access for definitive transluminal therapies that address the underlying lesion (1,2). In addition, it has been suggested that gradual, lowpressure reperfusion may offer certain advantages over sudden, high-pressure reperfusion associated with surgical revascularization (1,3,4). Recently, the Food and Drug Administration recalled urokinase (Abbokinase; Abbott Laboratories, Abbott Park, IL). As a result, a critical evaluation of alternate methods to treat acute limb ischemia with use of other thrombolytic drug strategies, PAT and/or PMT, will be needed. Reporting standards for the treatment of peripheral arterial disease (PAD) and practice guidelines for thrombolytic therapy for acute limb ischemia have been published (1,2,5– 7). However, there is insufficient evidence in the literature to determine the best therapy in a given case of acute limb ischemia. This is because the literature is replete with individual or institutional reports of surgical and thrombolytic therapy that are either biased or lack concurrent controls and standardized reporting practices (1). The purpose of this document is to establish reporting standards for subsequent studies pertaining to TRT in the treatment of acute limb ischemia. Consistent data reporting is needed to help precisely define the safety, efficacy, and long-term outcome of TRT procedures (1,8,9). Only then can the appropriate treatment be determined for patients presenting with acute limb ischemia.

Modified Use of the Arrow-Trerotola Percutaneous Thrombolytic Device for the Treatment of Thrombosed Hemodialysis Access Grafts

PURPOSE To assess the safety and efficacy of using the Arrow-Trerotola percutaneous thrombolytic device (PTD) as the sole means of mechanical thrombolysis in hemodialysis access grafts, including in situ treatment of the arterial plug. PATIENTS AND METHODS Fifty consecutive patients (22 women, 28 men; mean age, 58 years; mean graft age, 29 months), in whom mechanical thrombolysis of a thrombosed hemodialysis access graft using the PTD was planned, were included in the study. In all patients, the PTD was used to treat the arterial plug in situ at the arterial anastomosis, instead of using a Fogarty catheter to reposition the plug, as indicated in the PTD product labeling. Prospective data collection included demographic information, technical details of the procedure, immediate outcomes, and complications. Patients were followed for 3 months using definitions and data forms that were identical to those used in the original clinical trial of the PTD. A sample of procedures drawn from the PTD clinical trial database (n = 54) served as control. RESULTS Immediate technical patency was 100%. Complications included arterial embolization (6% versus 2% control; P = NS; all successfully treated with backbleeding); venous rupture (6% versus 2% control; P = NS); and sepsis (n = 1), probably due to occult graft infection. Adjunctive therapy with an Adherent Clot catheter was needed in two procedures (4%). Three month patency using life-table analysis was 42% (versus 39% control; P = NS). The number of subsequent interventions (surgical/percutaneous) to the arterial limb of the graft did not differ from the PTD trial, and no native arterial stenoses were detected during the follow-up period. CONCLUSIONS The PTD is safe and effective when used as the sole means of mechanical thrombolysis of hemodialysis grafts. Treating the arterial plug in situ with the PTD eliminates the need for a Fogarty or Adherent Clot catheter in 96% of procedures. A slight increase in arterial embolic complications was observed but these were easily treated with backbleeding.

Randomized Comparison of High-Flow versus Conventional Hemodialysis Catheters

PURPOSE To evaluate short-term flow rates achieved with a new split-tip polyurethane hemodialysis catheter. PATIENTS AND METHODS This was a prospective, randomized, nonblinded study. Patients referred for a tunneled-dialysis catheter received either a conventional silicone (Bard Hickman 13.5 F) if randomized to the control group, or a split-tip, high-flow polyurethane (MedComp AshSplit 14.5 F) catheter if randomized to the study group. Effective flow rates (QbEff) and recirculation were measured with use of ultrasonic dilution at pump settings (Qb) of 200, 300, 350 and 400 mL/min, as well as maximum Qb (QbMax, up to 500 mL/min) sustainable for at least 3 minutes. Measurements were repeated weekly for 6 weeks. Procedure times and initial and late complications were recorded. RESULTS Twelve patients were enrolled in each group, 11 and eight completed the study in the test and control groups, respectively. Insertion complications, limited to the split-tip group, included asymptomatic air embolus (n = 1), prolonged tunnel bleeding (n = 2), and kinking (n = 2). Recirculation in both groups was low (mean < 6% at all flow rates). QbMax was 499 mL/min in the Ash group and 470 mL/min in the Hickman group. A repeated measures analysis of variance was used. Adjusted (for week) mean effective flow rates (Qbeff, mL/min) were as follows: at Qb = 200, Ash = 211, Bard = 211, P = .93; at Qb = 300, Ash = 301, Bard = 292, P = .28; at Qb = 350, Ash = 341, Bard = 314, P = .03; at Qb = 400, Ash = 375, Bard = 329, P = .01; at QbMax, Ash = 422, Bard = 359, P = .0005. CONCLUSION Both catheters delivered flows within the acceptable range indicated by the Dialysis Outcomes Quality Initiative. The split-tip catheter is capable of higher flow rates (Qb and QbEff) compared with the conventional catheter, which may allow more efficient dialysis. Insertion complications appear to be higher with the new design.

Increase in Hepatic Arterial Blood Flow after Transjugular Intrahepatic Portosystemic Shunt Creation and its Potential Predictive Value of Postprocedural Encephalopathy and Mortality

PURPOSE To determine (i) whether there is a significant increase in hepatic artery blood flow (HABF) after transjugular intrahepatic portosystemic shunt (TIPS) creation and (ii) whether the extent of incremental increase in HABF is predictive of clinical outcome after TIPS creation. MATERIALS AND METHODS Prospective, nonrandomized, nonblinded duplex Doppler ultrasound (US) examinations were performed on 24 consecutive patients (19 men; Child Class A/B/C: 4/12/8, respectively) with a mean age of 52.8 years who were referred for TIPS creation for variceal bleeding. Peak hepatic artery velocity and vessel dimensions were used to calculate the hepatic arterial blood flow (HABF) before and after TIPS creation. Patients were clinically followed in the gastrohepatology clinic and TIPS US surveillance was performed at 1 and 3 months to assess shunt function. The extent of incremental increase in HABF was analyzed as a predictor of post-TIPS encephalopathy and/or death. RESULTS The technical success rate of TIPS creation was 100%. The shunt diameters were either 10 mm (n = 11) or 12 mm (n = 13). TIPS resulted in a significant reduction in the portosystemic gradient from 24.3 mm Hg +/- 5.7 to 9.3 mm Hg +/- 2.9 (P <.001). The hepatic artery peak systolic velocity and HABF increased significantly after TIPS creation, from 60.8 cm/sec +/- 26.7 to 121 cm/sec +/- 51.5 (P <.001) and from 254.2 mL/min +/- 142.2 to 507.8 mL/min +/- 261.3 (P <.001), respectively. The average incremental increase in HABF from pre-TIPS to post-TIPS was 253.6 mL/min +/- 174.2 and the average decremental decrease in portosystemic gradient was 15.0 mm Hg +/- 5.3, but there was no significant correlation (r = 0.04; P =.86) between the two. All shunts were patent at 30 and 90 days without sonographic evidence of shunt dysfunction. After TIPS creation, new or worsened encephalopathy developed in five patients at 30 days and in an additional three at 90 days. They were all successfully managed medically. Three patients (12.5%) died within 30 days of the TIPS procedure. The extent of incremental increase in HABF after TIPS was variable and did not correlate with the development of 30-day and 90-day encephalopathy (P =.41 and P =.83, respectively) or 30-day mortality (P =.2). CONCLUSIONS HABF increases significantly after TIPS but is not predictive of clinical outcome. The significance of the incremental increase is yet to be determined.

Accuracy of CO2 Angiography in Vessel Diameter Assessment: A Comparative Study of CO2 versus Iodinated Contrast Material in an Aortoiliac Flow Model

PURPOSE Precise vessel sizing prior to endovascular intervention is critical to achievement of technical success. Diameter measurements obtained with CO2 and iodinated contrast material in an aortoiliac flow model were compared. MATERIALS AND METHODS Aortoiliac flow was simulated in a compliant, silicone elastomer phantom of the aortoiliac system using an autoperfusion pump (flow volume, approximately 1100 mL/min; mean arterial pressure, 70-80 mm Hg at 80-90 cycles/minute) and a glycerol solution (40% by weight; viscosity 3.7 centipoise at 20 degrees C). Digital subtraction angiography was performed with the phantom in the anteroposterior (AP) plane and in three oblique planes with both CO2 and iodinated contrast material. Five sets of images for both CO2 and iodinated contrast material were obtained for each projection. Two readers independently performed vessel diameter measurements at seven sites (distal abdominal aorta, bilateral proximal and distal common iliac, and mid-external iliac arteries). The model was then evaluated with intravascular ultrasound (IVUS) using a 20-MHz imaging catheter. Actual diameter measurements were taken from the inner wall to inner wall in orthogonal planes at the same locations within the model, as described previously. Analysis was performed to determine local difference in measurements (t tests), difference when compared to the standard AP projection with iodinated contrast material (Dunnetts test) and inter-reader variability (Pitmans test). RESULTS The contralateral iliac vessel segment did not opacify when imaging with CO2 in the 45 degrees obliquities; thus, 22 of 28 sites were available for comparison. At 18 of 22 (81.8%) sites, there was significant difference in vessel measurements (P < .01), with CO2 yielding a significantly larger diameter at 17 of 22 (77.3%) of the sites. The difference in mean diameter ranged from -1.28 to 4.47 mm. With use of the AP iodinated contrast material run as the standard, there were significant differences (P < .05) in vessel diameter at 17 of 22 (77.3%) and four of 21 (19%) sites for CO2 and iodinated contrast material respectively, with CO2 tending toward greater diameter measurements. Significant differences (P < .05) in variance between the two readers were present but occurred primarily with CO2 in the AP projection and iodinated contrast material in the 45 degrees left obliquity. With use of IVUS as the standard, there were significant differences (P < .05) in the measured vessel diameters with CO2 at nine of 22 (40.9%) of the sites and with iodinated contrast material at 17 of 28 (60.7%) of the sites. Of the measurements made with CO2, seven of nine (77.8%) of the measurements were of larger diameter than those obtained with IVUS. By contrast, of the measurements made with iodinated contrast material angiography, IVUS measured larger diameters in 16 of 17 (94.1%). CONCLUSION CO2 angiography consistently yielded significantly larger vessel measurements when compared to both iodinated contrast angiography and WVUS. These results have important implications in regards to planning intervention based solely on CO2 angiography. Further evaluation is needed before recommending CO2 for vessel sizing in clinical practice.

Single-Step Dilation for Large-Bore Percutaneous Gastrostomy and Gastrojejunostomy

O SCVIR, 1998 PERCUTANEOUS gastrostomy and gastrojejunostomy are well established techniques that have excellent technical success rates and very few complications (1-5). One of the differences between percutaneous interventional radiologic techniques and surgical and percutaneous endoscopic techniques is the size of the catheter placed. Most percutaneous gastrostomy tubes are 12-14 F and percutaneous jejunostomy tubes range from 12 to 24 F, while endoscopically and surgically placed tubes are typically much larger (6). Smaller bore tubes may be more prone to clogging, as well as to mechanical problems such as kinking and breakage (5,7). Our experience with patient and referring physician complaints about smallbore gastrostomy and gastrojejunostomy tubes led us to consider placement of larger bore tubes. Several such tubes are available, most commonly consisting of Silastic balloon tip catheters ranging in diameter from 18 to 24 F. Smaller gastrojejunostomy tubes can be placed coaxially through these catheters and have adapters to fit them conveniently to the existing gastrostomy tube. One of the problems in initial placement of large-bore gastrostomy and gastrojejunostomy tubes is tract dilation. Even when gastropexy is used, the forces associated with serial dilation with rigid dilators mav cause detachment of the gastropexy and even inadvertent placement of the tube into the peritoneal cavity. Furthermore, with each dilator exchange there is a risk of spillage of gastric contents into the peritoneal cavity with subsequent peritonitis. We describe a technique for single-step tract dilation and peel-away sheath placement that circumvents these potential problems.

Percutaneous Transmyocardial Intracardiac Retroperfusion Shunts: Technical Feasibility in a Canine Model

PURPOSE To test the technical feasibility of creating a left ventricle to coronary sinus shunt using endovascular techniques. MATERIALS AND METHODS By means of a right jugular vein approach, a needle puncture was made from the coronary sinus to the left ventricle in 10 dogs. The tracts were balloon dilated and lined with 6-mm Wallstents. Shunt patencies, immediate and 4-hours later, were fluoroscopically assessed by contrast material injection into the left ventricle. Blood pressure, pulse, oxygen saturation, and cardiac rhythm were monitored. The dogs were then euthanized. Thoracic cavities and hearts were dissected and inspected. RESULTS Technical success and immediate shunt patency were 100%. No cardiac dysrhythmias, electrocardiographic changes, or reduction in voltage potential were seen. Eight (80%) of the shunts were patent at 4 hours, one (10%) had thrombosed, and one dog died. Nine (90%) dogs had no pericardial hematoma and one (10%) had minimal pericardial blood from needle passes into the pericardial sac. The coronary sinuses were intact and no injuries to the valve leaflets or chordae tendineae were seen. The puncture sites were from the coronary sinus, 1-2 mm (mean, 1.3) from its auricular orifice, into the left ventricle, just below the inferior margin of the posterior leaflet of the mitral valve. One dog died at 3 hours with no preceding electrocardiographic evidence of impending demise. Autopsy showed no pericardial hematoma and the heart findings were no different from the other nine dogs. CONCLUSIONS Creation of a left ventricle to coronary sinus shunt with use of endovascular techniques is technically feasible. Study of a transmyocardial intracardiac coronary retroperfusion shunt to deliver oxygenated blood to the ischemic myocardium is warranted.

Endovascular Repair of Arterial Pseudoaneurysms with Use of a Perfusion Balloon Catheter

PURPOSE Pseudoaneurysms represent contained disruption of the arterial wall. Iatrogenic pseudoaneurysms frequently complicate complex endovascular procedures. With use of an animal model, the authors attempted to determine the safety and efficacy of using a perfusion balloon catheter (PBC) to thrombose surgically created pseudoaneurysms. MATERIALS AND METHODS An in vitro system measured maximum flow volume through a 5-F PBC. Pseudoaneurysms were created in domestic swine with use of a jugular vein patch anastomosed to a femoral arteriotomy. The PBC was inflated across the pseudoaneurysm neck for 30-minute intervals until thrombosis was confirmed by ultrasound. Completion arteriography was performed to evaluate for vascular complications. RESULTS Maximum flow through the PBC was 62.6 mL/min measured at a constant pressure gradient of 120 mm Hg. Five pseudoaneurysms were created in four animals. The PBC completely thrombosed all five lesions. The mean treatment duration was 129 minutes (+/- 39 minutes SD). No native arterial injury, in situ thrombus, or distal embolization occurred. Partial recanalization of three of the five treated pseudoaneurysms was identified on follow-up arteriography and gross sectioning (n = 2 and n = 1, respectively). CONCLUSION The PBC safely and effectively thrombosed surgically created pseudoaneurysms. Partial recanalization of treated pseudoaneurysms was demonstrated. Clinical trials are warranted.