Robert T. Andrews

Utility of Nonselective Abdominal Aortography in Demonstrating Ovarian Artery Collaterals in Patients Undergoing Uterine Artery Embolization for Fibroids

PURPOSE To review the incidence of ovarian collateral supply to uterine fibroids as demonstrated by nonselective abdominal aortography before uterine artery embolization (UAE) and to evaluate the effect of such visualization on interventional management. MATERIALS AND METHODS The aortograms of 51 consecutive patients (mean age, 42.4 y; range, 30--53 y) undergoing UAE for symptomatic uterine fibroids were reviewed retrospectively for the visualization of ovarian arteries extending into the pelvis. If ovarian arteries were visualized, their size relative to the ipsilateral external iliac artery was measured. Arteries believed large enough to represent a significant blood supply to the uterine fibroids were further evaluated after UAE to determine whether flow persisted. RESULTS In 13 of 51 patients (25%), a total of 18 ovarian arteries were identified. They were bilateral in five patients and unilateral in eight. Their sizes relative to the ipsilateral external iliac artery ranged from 8% to 57% (mean, 26%). Eight ovarian arteries with a relative size > or = 25% were further evaluated. Five of the eight (62.5%) were not visible after UAE. Of the three persistent ovarian collateral arteries, two were successfully embolized. The patient with the untreated collateral artery experienced persistent menorrhagia. CONCLUSION Preembolization aortography with the catheter tip at level of the renal arteries demonstrated ovarian collateral arteries in 25% of patients with uterine fibroids. However, their detection influenced treatment in only 6% of the reported cases.

Stent-Grafts for De Novo TIPS: Technique and Early Results

PURPOSE To evaluate the potential benefits of placing a polytetrafluoroethylene (PTFE)-covered stent-graft during initial creation of a transjugular intrahepatic portosystemic shunt (TIPS) in clinical practice. MATERIALS AND METHODS De novo TIPS were created with a PTFE stent-graft in four male and four female patients with symptomatic portal hypertension awaiting liver transplant. Their ages ranged from 35 to 62 (mean, 47) years. Patients were followed with TIPS ultrasound (US) and/or venography until liver transplantation or death; one remains under active study. Six recovered specimens underwent gross and microscopic evaluation. RESULTS All TIPS placements were successful. Six shunts were primarily patent, with a mean patency of 289 days, through completion of the study. Five were found to be patent at transplant and one was found to be patent at autopsy. Explant evaluation revealed a smooth, thin layer of neointima and exclusion of biliary secretions. Three patients developed a total of four stenoses (one tandem lesion) during follow-up, leading to revision in two patients. Mean primary and total patency in these patients was achieved after 279 and 463 days, respectively. A previously occult moderate stenosis was detected after explant in another patient. Only one (nonsignificant) stenosis clearly developed in an area covered by PTFE. CONCLUSION Placement of a de novo PTFE stent-graft during TIPS creation is feasible and may extend primary shunt patency. Appropriate positioning of the stent-graft is critical.

Successful embolization of collaterals from the ovarian artery during uterine artery embolization for fibroids: a case report.

JVIR 2000; 11:607–610 UTERINE artery embolization (UAE) (also known as uterine fibroid embolization) as a definitive treatment for symptomatic uterine leiomyomata was first reported in 1995 (1). While this and subsequent reports have shown great promise for the technique, clinical failure has been seen in as many as 20% of patients (2–7). Among that group have been women undergoing unilateral embolization or having arterial supply to their fibroids from sources other than the uterine artery (3,7,8). This report describes a patient in whom the right ovarian artery provided the dominant arterial supply to a uterine fibroid. These collateral branches were selectively embolized via the ovarian artery with use of a microcatheter technique, giving satisfactory clinical and anatomic results.

PLACEMENT OF A FLEXIBLE ENDOVASCULAR STENT ACROSS THE FEMORAL JOINT : AN IN VIVO STUDY IN THE SWINE MODEL

PURPOSE To investigate the effects of joint motion on the structural integrity of periarticular stents and on the development of neointimal hyperplasia within these devices. MATERIALS AND METHODS In four juvenile farm swine, Wall-stents were implanted in the common femoral arteries and contralateral common femoral veins, centered at the point of maximal conformational change during passive hip flexion. Control stents were placed in the aortae and iliac veins. Angiography and transcatheter blood pressure measurements were obtained across each stent, with periarticular stents studied in flexion and extension. Two animals underwent repeated evaluation after 1 month, the others after 3 months. Findings were correlated with gross and histopathologic findings in the harvested stents. RESULTS No stent fractures occurred. One femoral vein was injured during stent placement and was occluded 1 month later at follow-up. Hemodynamically significant stenoses were identified in one arterial stent and one venous stent at 3 months. The amount of neointimal hyperplasia was greater in periarticular stents than in controls and greater in animals studied at 1 month than in those studied at 3 months. The pattern of neointimal hyperplasia within mobile arteries was circumferentially asymmetric and thicker at the distal ends of the stents. Venous neointimal hyperplasia was thicker and markedly different in character than that seen in arterial stents from the same animals. CONCLUSIONS Periarticular Wallstents and the underlying vascular anatomy remained structurally intact despite the stresses of repetitive motion during a 3-month period. Stents deployed across joints or in venous locations may be at greater risk for neointimal hyperplasia development and eventual occlusion than those deployed in immobile vessels and arteries. Neointimal hyperplasia may decrease in thickness after an initial period of exuberant development. Additional studies are necessary to determine long-term outcomes.

Entrapment of J-Tip Guidewires by Venatech and Stainless-Steel Greenfield Vena Cava Filters During Central Venous Catheter Placement: Percutaneous Management in Four Patients

We present four patients in whom beside placement of a central venous catheter was complicated by entrapment of a J-tip guidewire by a previously placed vena cava (VC) filter. Two Venatech filters were fragmented and displaced into the superior VC or brachiocephalic vein during attempted withdrawal of the entrapped wire. Two stainless-steel Greenfield filters remained in place and intact. Fluoroscopically guided extraction of both wires entrapped by Greenfield filters was successfully performed in the angiography suite.

Training Standards for Physicians Performing Uterine Artery Embolization for Leiomyomata: Consensus Statement Developed by the Task Force on Uterine Artery Embolization and the Standards Division of the Society of Cardiovascular & Interventional Radiology—August 2000

UTERINE artery embolization (UAE) is a therapy that offers an alternative to traditional surgical procedures such as myomectomy and hysterectomy for women with symptomatic leiomyomata (fibroids). The clinical experience and the published literature indicate that this is an effective and safe therapy (1–9). For patients to receive the best possible care before, during, and after the embolization procedure, the Society of Interventional Radiology Task Force on Uterine Fibroid Embolization has developed this consensus statement to define the appropriate qualifications for physicians practicing in this field.

A Canine Model for Studying Endoleak after Endovascular Aneurysm Repair

PURPOSE The aim of this study was to create an animal model of endoleak after stent-graft placement for abdominal aortic aneurysm (AAA) in which a large aneurysmal sac would be preserved for the testing of techniques for its percutaneous occlusion. MATERIALS AND METHODS Infrarenal AAAs were created in nine dogs by anastomosis of an isolated segment of the inferior vena cava to the right side of the abdominal aorta in combination with a large anterior patch from the external jugular vein. One hour later, animals underwent percutaneous implantation of polytetrafluoroethylene-covered Z stent endografts with three 3-mm-diameter holes through the fabric. Aortograms were obtained before and after surgery, after endograft placement, and at the time of animal sacrifice at 1 week or 1, 2, 3, or 6 months. Pressures within the aorta and the aneurysm sac were recorded before animal sacrifice. Gross and histologic evaluations of the specimens were then carried out. RESULTS Immediately after endograft placement, all nine animals had artificial type III endoleaks with angiographic filling of lumbar arteries and veins. One animal died of surgical complications within 2 days of surgery and is not included in our data analysis. One aneurysm ruptured at 1 week. At completion of the study, six endografts were patent and two were occluded. The aneurysm sac had enlarged by approximately 50% in seven animals. At follow-up, type I endoleak was present in three animals, type II endoleak was present in three, and the artificial type III endoleak was present in all six animals with patent endografts. The pressure differential between aorta and aneurysm sac was 36 mm Hg, with a mean aortic pressure of 87 mm Hg +/- 13.3 and a mean aneurysmal sac pressure of 51 mm Hg +/- 28.1. The aneurysmal sac exhibited early thrombus formation at 1 week, which progressed to complete thrombosis in 1-6 months. CONCLUSIONS The model is technically feasible but would be useful in testing occlusive techniques for residual aneurysm sacs only in the acute phase after endograft placement. It would be not reliable for chronic evaluation because of rapidly progressive thrombosis in most aneurysm sacs and occasional complete thrombosis of the AAA and endograft.

An evaluation of commonly employed central venous catheter kits and their potential risk for complications of excess guidewire introduction.

STUDY OBJECTIVE To evaluate the components of commonly used central venous catheter kits with respect to the potential for guidewire-mediated complications during catheter placement.Prospective, nonrandomized, observational study. SETTING Six academic hospitals across the United States. PATIENTS None. INTERVENTIONS None. MEASUREMENTS AND MAIN RESULTS 30 commercially manufactured catheter kits (15 tunneled, 15 nontunneled) were opened and evaluated. The catheter or sheath to be introduced was measured and a corresponding ideal guidewire length was calculated. The ideal length was then compared to the actual length, and differences were tabulated. Wire tip configuration and the presence and pattern of distance markings were recorded and, in conjunction with the catheter and wire length discrepancies, were used to grade the relative risk of introducing excess guidewire during catheter placement. Of 30 kits evaluated, 14 (46.7%) had guidewires more than 20 cm longer than necessary. The mean excess wire length was 15 cm (range: 8 to 55 cm) and did not differ significantly between tunneled and nontunneled catheter kits. Only 10 kits (33.3%) had distance markings of any type, and there was no standardization among them; none corresponded to previously published recommendations. There was potential risk of excess wire introduction in 18 catheter kits, of which seven were nontunneled devices designed for bedside placement. CONCLUSIONS The design of commonly employed central venous access catheter kits is such that there is a mismatch between guidewire and catheter length and a general lack of guidewire markings. We believe that these designs may predispose to the introduction of excess guidewire and result in guidewire-mediated complications during catheter placement. This risk can likely be reduced by matching the guidewires to the devices placed over them and by standardizing guidewire distance markings.

Fallopian tube occlusion with use of a small intestine submucosa device: Evaluation in a rabbit model

PURPOSE The present study evaluates the short- and midterm efficacy of a small intestinal submucosa (SIS) device for fallopian tube occlusion in rabbits. MATERIALS AND METHODS In a pilot study, several SIS device designs were tested for positional stability (absence of migration). The design selected for further testing consisted of a center of spongy SIS surrounded by an SIS sheet and held together by a 0.006-inch wire helix with two barbs. It was delivered on the tip of a short coaxial 3-F/5-F catheter set. Using this design, bilateral transuterine fallopian tube occlusion was performed in eight New Zealand White rabbits. Follow-up consisted of plain radiography at 2 weeks and hysterosalpingography at 6 weeks (n = 4 animals; eight tubes), 12 weeks (n = 2 animals; four tubes), or 24 weeks (n = 2 animals; four tubes). Thereafter, the animals were killed and the fallopian tubes were harvested for histologic evaluation. RESULTS A single device was placed successfully in each fallopian tube. Fifteen of 16 devices (94%) remained in place throughout follow-up. One device migrated into the vagina at 2-week follow-up. Hysterosalpingography of the 15 tubes with occluders in place showed occlusion in seven of seven (100%) at 6 weeks, three of four (75%) at 12 weeks, and two of four (50%) at 24 weeks. Histologic evaluation revealed luminal occlusion by reorganized SIS containing macrophages, fibrocytes, and scant foreign-body giant cells. Only a mild inflammatory reaction was observed around the tube. In the animals with recanalization at 12 and 24 weeks, new channels were found alongside the original still-occluded fallopian tube lumen. CONCLUSIONS The original lumen of the fallopian tube was effectively occluded by the SIS occluder, which was remodeled within the fallopian tubes of rabbits. Partial peripheral recanalization was observed over time.

Lack of Suitability of the Rabbit Model for Particulate Uterine Artery Embolization

PURPOSE The goal of this study was to evaluate the rabbit model for studies of particulate uterine artery embolization (UAE). Rabbits were chosen because it was believed that their year-round breeding time and short duration of pregnancy would be useful in studies of fertility and pregnancy after UAE. MATERIALS AND METHODS Bilateral UAE was performed in 12 adult female New Zealand White rabbits weighing 4-5.2 kg. All animals were proven to be breeders before treatment. Each uterine artery was embolized to stasis with use of 180-300- microm polyvinyl alcohol (PVA) particles (n = 9 animals), 500-710- microm PVA particles (n = 1), or tris-acryl 500-700- microm gelatin microspheres (n = 2). RESULTS Two rabbits died 7 days after embolization and the other 10 rabbits had to be killed because of malaise and weight loss 4-8 d after embolization. In all animals, necropsy demonstrated extensive uterine necrosis sparing only the tip of the uterine horn. CONCLUSION Rabbits are an unsuitable model for studies of UAE with the embolic agents in clinical use.