Crotalus durissus terrificus (viperidae; crotalinae) envenomation: Respiratory failure and treatment with antivipmyn TRI® antivenom

We report an envenomation to a professional herpetologist by a South American rattlesnake (Crotalus durissus terrificus) that resulted in respiratory failure, and therapeutic improvement following antivenom administration. A 56-year-old male was bitten on the left wrist by a Crotalus durissus terrificus (C. d. terrificus) while attempting to tube the snake for maintaining safe control while performing venom extraction. The patient was intubated due to rapidly ensuing respiratory failure and administration of Antivipmyn-TRI^® was initiated while being transported via ambulance. The patient was admitted to the hospital unconscious and unresponsive. Mechanical ventilation was required until 5 h after completion of antivenom administration. No significant adverse effects were observed with antivenom administration. The patient was discharged approximately 55 h following envenomation. This is the first reported case in the United States of a patient following a C. d. terrificus envenomation with consequent respiratory failure, and in which Antivipmyn-TRI^® was successfully administered.

Endovascular AAA repair in patients with renal insufficiency: strategies for reducing adverse renal events

Vascular imaging, usually employing nephrotoxic contrast agents is relied upon for all aspects of endovascular AAA repair causing some to consider renal insufficiency a relative contraindication. We sought to determine if endovascular AAA evaluation and repair could be successfully accomplished by minimally or non-nephrotoxic modalities. Records and results for 98 consecutive patients undergoing endovascular AAA repair were reviewed. Patients requiring dialysis preoperatively were excluded (N=3). The average volume of iodinated contrast agent employed for intraoperative imaging was 152 cc (35-420 cc). Twenty patients (20%) had baseline renal insufficiency (serum creatinine > or =1.3 mg/dl). A rise in serum creatinine above baseline was observed in 23 (24%) patients following repair; for 15 (16%) this was permanent. Creatinine rise occurred in patients with both normal (15) and abnormal (8) baseline values (P=0.09). Rise in creatinine was independent of contrast volume employed and of the use of infrarenal vs suprarenal device fixation (P>0.05). Two (2%) patients required permanent dialysis, one of which had a normal baseline creatinine and unclear etiology for renal failure, the other had a baseline creatinine of 2 and required device placement over an accessory renal artery. Strategies to minimize the use of nephrotoxic contrast for patients with renal insufficiency included the use of MRA, rather than contrast-CT for pre and postoperative imaging (7, 35%) and use of Gadolinium rather than iodinated contrast for performance of intraoperative arteriography (5, 25%). Endovascular grafts were successfully designed and implanted based upon MRA as the sole preoperative imaging modality in every case in which it was attempted (7). Mortality was not significantly different between those with and without abnormal baseline renal function (P>0.05). Adverse events (access failures, arterial injuries, blood loss, endoleaks) were not significantly correlated with baseline renal insufficiency, rise in creatinine from baseline, use of MRA or intraoperative Gadolinium angiography (P>0.05).Pre- and postoperative evaluation and performance of endovascular AAA repair can be accomplished in patients with renal insufficiency without increasing the rate of mortality or adverse events employing a strategy which minimizes the use of nephrotoxic contrast agents, relying upon Gadolinium arteriography and MRA. Endovascular grafts can be successfully planned and followed employing MRA as the sole imaging modality.

Impact of exclusion criteria on patient selection for endovascular abdominal aortic aneurysm repair

PURPOSE

Wide-ranging predictions have been made about the usefulness of endovascular repair for patients with abdominal aortic aneurysms (AAAs). The availability of US Food and Drug Administration-approved devices has removed the restrictions on patient selection, which had been controlled by device trials. This study examined the applicability of endovascular AAA repair and identified the anatomic barriers to successful endovascular AAA repair that should guide future device development.

METHODS

All patients who came to our institution for infrarenal AAA repair between April 1998 and June 2000 were offered evaluation for endovascular repair. Thin-cut spiral computed tomography scans and arteriograms were obtained on all patients, and their anatomic characteristics were prospectively entered into a database. A wide selection of available devices allowed the treatment of diverse AAA anatomic features.

RESULTS

A total of 307 patients were examined (264 men, 43 women). Of these, 204 patients (66%; 185 men, 19 women) underwent endovascular repair, and 103 patients (34%, 79 men, 24 women) were rejected. Reasons for exclusion included short aneurysm neck (56, 54%), inadequate access because of small iliac arteries (48, 47%), wide aneurysm neck (41, 40%), presence of bilateral common iliac aneurysms extending to the hypogastric artery (22, 21%), excessive neck angulation (14, 14%), extensive mural thrombus in the aneurysm neck (10, 10%), extreme tortuosity of the iliac arteries (10, 10%), accessory renal arteries originating from the AAA (6, 6%), malignancy discovered during the examination (5, 5%), and death during the examination interval (2, 2%). Rejected patients had an average of 1.9 exclusion criteria (range, 1 to 4). A disproportionate number of women were excluded because of anatomic findings (P = .0009). Although 80% of patients who were at low risk for surgery qualified for endovascular repair, only 49% of our patients who were at high risk for surgery were acceptable candidates (P < .001). Of the 103 patients who were excluded, 34 (33%) underwent open surgical repair, and the remaining 69 (67%) were deemed to be unfit for open surgery. Three patients (1.4%) failed endograft placement because of inadequate vascular access.

CONCLUSION

Most infrarenal AAAs (66%) can be treated with endovascular devices currently available commercially or through US Food and Drug Administration-approved clinical trials. However, patients who are at high risk for surgery and might benefit most from endovascular repair are less likely to qualify for the procedure (49%). Men (70%) are more likely than women (40%) to meet the anatomic criteria for endografting. Difficulties with vascular access and attachment site geometry predominate as reasons for exclusion. Our findings suggest that smaller profile devices, which can negotiate small and tortuous iliac arteries, are needed. Proximal and distal attachment site problems require devices that can accommodate wide and angulated attachment necks and achieve short seal zones.

Diagnosis and management of type 2 endoleaks after endovascular aneurysm repair

Endovascular repair is a major treatment advance in patients with large infrarenal abdominal aortic aneurysms. Since the FDA approved two commercial devices 2.5 years ago, over 40,000 patients have undergone this procedure in the United States. Although we have learned a great deal, more than a few mysteries relating to the long-term performance of these devices remain. This results in never-ending surveillance protocols searching for graft failure and aneurysm expansion. One of the especially contentious issues is the management of type 2 endoleaks. Unlike other endoleaks that are related to problems with the graft and/or fixation, this type of leak occurs in patients with properly functioning devices. This is why so much controversy exists about whether or not these patients must be treated. Some advocate "watchful-waiting" intervention only when there is aneurysm expansion. Others routinely treat patients with type 2 endoleaks in an attempt to prevent expansion. As with most controversial topics, if you look carefully, there is more agreement than disagreement between the two groups. In this review, we will first describe the methods used for endoleak diagnosis and treatment. We will then review our current endoleak treatment algorithm and explain its rationale for use.

Upper gastrointestinal hemorrhage and transcatheter embolotherapy: clinical and technical factors impacting success and survival

PURPOSE

To identify clinical and technical factors influencing the outcome of transcatheter embolotherapy for nonvariceal upper gastrointestinal (GI) hemorrhage and to quantify the impact of successful intervention on patient survival.

MATERIALS AND METHODS

A retrospective review was performed of all patients (n = 163) who underwent arterial embolization for acute upper GI hemorrhage at a university hospital over an 11.5-year period. Clinical success was defined as target area devascularization that resulted in the clinical cessation of bleeding and stabilization of hemoglobin level. The clinical condition of each patient at intervention was defined by history, laboratory examination, and two composite indicator variables. With use of logistic regression, the dependent variable, clinical success, was modeled on two categories of clinical and technical variables. A final model regressed patient survival on clinical success and other clinical variables.

RESULTS

None of the procedural variables analyzed had a significant influence on clinical success. Several clinical variables did impact clinical success, including multiorgan system failure (OR, 0.36; P =.030), coagulopathy (OR, 0.36; P =.026), and bleeding subsequent to trauma (OR, 7.1; P =.040) or invasive procedures (OR, 6.5; P =.009). Regardless of their clinical condition at intervention, patients who underwent clinically successful embolization were 13.3 times more likely to survive than those who had an unsuccessful procedure (CI, 4.54-39.2; P =.000). Nevertheless, patients with multiorgan system failure were 17.5 times more likely to die, independent of the outcome of the procedure (CI, 0.014-0.229; P =.000).

CONCLUSION

Arresting nonvariceal upper GI hemorrhage with transcatheter embolotherapy has a large positive effect on patient survival, independent of clinical condition or demonstrable extravasation at intervention. Aggressive treatment with transcatheter embolotherapy is advisable in patients with acute nonvariceal upper GI hemorrhage.

Risk factors for liver abscess formation after hepatic chemoembolization

PURPOSE

To assess the frequency and risk factors for liver abscess after hepatic chemoembolization.

MATERIALS AND METHODS

The authors performed retrospective analysis of 397 chemoembolization procedures in 157 patients. All patients received prophylactic intravenous antibiotics before the procedure and 5 days of oral antibiotics after the procedure. The association between abscess formation and risk factors was determined with use of chi(2) analysis and the Fisher exact test and expressed as an odds ratio.

RESULTS

Liver abscess occurred in seven of 157 patients (4.5%) after eight of 397 procedures (2.0%) at a mean of 19 d +/- 7 after chemoembolization. No patients had neutropenia. Organisms isolated reflected intestinal flora. Six patients required percutaneous drainage for 35 d +/- 29. The seventh patient required drainage for the remainder of life as a result of a nonhealing biliary fistula. Three of 24 patients with neuroendocrine tumors had abscesses (12.5%; odds ratio, 4.6; 95% CI, 0.96-22.1; P =.07), as did three of 14 patients with gastrointestinal sarcomas (21%; odds ratio, 9.5; 95% CI, 1.9-47.8; P =.016), and one of two with pancreatic adenocarcinoma. Six of the seven patients with abscesses underwent a Whipple procedure before chemoembolization. Only one patient with a history of a Whipple procedure did not develop an hepatic abscess. In the absence of a bilioenteric anastomosis, abscess occurred in only one of 150 patients (0.7%), or one of 383 procedures (0.3%). The odds ratio for liver abscess among patients with a bilioenteric anastomosis was 894 (95% CI, 50-16,000; P <.0001).

CONCLUSION

Earlier bilioenteric anastomosis is the major determinant of liver abscess formation after hepatic chemoembolization. The prophylaxis regimen used failed to prevent abscess formation in patients with earlier bilioenteric anastomosis.

Balloon embolization of the internal iliac artery before aneurysm endograft deployment

Six patients, ranging from 69 to 81 years of age, underwent iliac artery embolization with use of Detachable Silicon Balloons (DSB) 11-14 days before stent-graft repair of aneurysms. Balloons of 8.8-mm, 9.4-mm, and 9.9-mm sizes were used with 20-30 g of release force. Deployment difficulty was experienced in three cases. Five of six cases were successful, with the iliac artery remaining occluded at the time of endografting; one case required subsequent coil replacement. The average operative time for balloon embolization (75 min +/- 28) was shorter than that in 18 cases of coil embolization performed within the same time period (111 min +/- 105), but the difference was not significant (P = .21). Postoperatively, one patient (17%) reported buttock claudication after the procedure. Use of the DSB represents an alternative to use of coils for embolization of large and tortuous iliac arteries.

Carotid MR angiography: phase II study of safety and efficacy for MS-325

PURPOSE

To evaluate the safety and efficacy of MS-325 in patients suspected of having carotid arterial disease.

MATERIALS AND METHODS

Fifty carotid arteries in 26 patients were imaged with three-dimensional spoiled gradient-recalled-echo magnetic resonance (MR) angiography at 5 and 50 minutes after injection of MS-325. MS-325 was administered intravenously as a single dose of 0.01, 0.03, or 0.05 mmol per kilogram of body weight as determined with a dose randomization scheme for four, nine, and 13 patients, respectively. Safety, including clinical laboratory changes and electrocardiographic monitoring, was assessed until approximately 3 days after injection. Conventional contrast agent-enhanced angiography was used as the standard of reference. Independent readers blinded to the dose interpreted the MR angiographic and conventional images. Images were assessed for location and extent of carotid arterial stenosis.

RESULTS

There were no severe or serious adverse events. For the determination of clinically significant stenosis (>70%) on the 5-minute images, sensitivity, specificity, and accuracy (P =.07, three-way comparison) were 100%, 100%, and 100%; 63%, 100%, and 88%; and 40%, 75%, and 55% at 0.01, 0.03, and 0.05 mmol/kg, respectively. Sensitivity and specificity for images at 50 minutes after MS-325 administration showed the same trends as the 5-minute images.

CONCLUSION

Overall accuracy for MS-325-enhanced carotid MR angiography performed during steady-state conditions of circulating contrast agent approximately 5 minutes after injection was high (88%-100%) at 0.03 and 0.01 mmol/kg. MS-325 was well tolerated at all evaluated doses.

Pulmonary arteriovenous malformations: three-dimensional gadolinium-enhanced MR angiography-initial experience

PURPOSE

To determine whether three-dimensional gadolinium-enhanced magnetic resonance (MR) angiography could be used to identify pulmonary arteriovenous malformations (PAVMs) and to accurately identify the size and number of feeding arteries.

MATERIALS AND METHODS

Eight patients suspected of having PAVM were examined with three-dimensional MR angiography at 1.5 T. Images were reviewed by a single radiologist blinded to conventional angiographic findings who evaluated each image for the size, number, and location of PAVMs, as well as for the size and number of feeding arteries. Five patients underwent conventional angiography with embolization therapy, and one patient underwent lobectomy. Two patients did not undergo either surgery or angiography.

RESULTS

Three-dimensional MR angiography revealed nine (90%) of 10 PAVMs that were confirmed at conventional angiography (n = 9) or examination of a surgical specimen (n = 1). The single PAVM that was not identified prospectively at MR angiography was small (3-4 mm) and peripheral. Two additional PAVMs were identified in the two patients who did not undergo surgery or angiography.

CONCLUSION

Three-dimensional MR angiography is a promising technique for use in the diagnosis of PAVM, although small (<5-mm) PAVMs may be more difficult to identify with the technique. The technique is a particularly useful means of noninvasively demonstrating the size and number of feeding arteries prior to treatment.

The role of magnetic resonance angiography for endoprosthetic design

OBJECTIVES

Many patients with aortic aneurysms have renal insufficiency and may be at increased risk when conventional imaging modalities (contrast-enhanced computed tomography and arteriography) are used for aortic endograft design. Our objective was to determine if magnetic resonance angiography (MRA) could be used as the sole imaging modality for endoprosthetic design.

METHODS

A total of 96 consecutive patients who underwent endovascular repair of thoracic (5) and abdominal (91) aortic aneurysms (April 1998-December 1999) were included in this study. Data were collected prospectively. Gadolinium-enhanced MRA was used preoperatively in place of conventional imaging if renal insufficiency or a history of severe contrast reaction was present. The control group underwent conventional imaging. Endografts used included Ancure, AneuRx, and Talent.

RESULTS

Fourteen patients (14.6%) had their endografts designed solely with MRA. Intraoperative access failure; proximal and distal extensions (unplanned); conversion to open, aborted procedures; and endoleaks occurred with equal frequency in both the MRA-designed and control groups (16.7% vs 18.3%, respectively; P =.33). Despite baseline renal insufficiency, there was no significant rise in the creatinine level after endograft implantation in patients with an MRA design (preoperative level, 1.8; postoperative level, 1.9; P =.5).

CONCLUSION

MRA may be successfully used as the sole modality for aortic endograft design. The use of MRA for this purpose is noninvasive and minimizes nephrotoxic risk.

Sarcomas metastatic to the liver: response and survival after cisplatin, doxorubicin, mitomycin-C, Ethiodol, and polyvinyl alcohol chemoembolization

PURPOSE

To evaluate the response to and survival after chemoembolization with cisplatin, doxorubicin, mitomycin-C, Ethiodol, and polyvinyl alcohol for patients with sarcomas metastatic to the liver that are surgically unresectable.

MATERIALS AND METHODS

Sixteen patients were treated. Primary tumors included 11 gastrointestinal leiomyosarcomas, two splenic angiosarcomas, one leiomyosarcoma of the broad ligament, one leiomyosarcoma of the inferior vena cava, and one malignant fibrous histiocytoma of the colon. Chemoembolization with cisplatin, doxorubicin, mitomycin-C, Ethiodol, and polyvinyl alcohol particles was performed 1-5 times at approximately monthly intervals (mean, 2.8). Pre- and posttreatment cross-sectional imaging was performed 1 month after completion of treatment and then every 3 months. Thirty-day response was graded according to World Health Organization/Eastern Cooperative Oncology Group criteria. Survival was calculated with use of Kaplan-Meier analysis.

RESULTS

Two patients (13%) exhibited partial morphologic response, 11 patients (69%) were morphologically stable, and three (19%) demonstrated progression of disease 30 days after completion of treatment. Among the 13 responders, two underwent partial hepatectomy after initial treatment. Seven developed intrahepatic progression at a mean of 10 months and a median time of 8 months. The remaining four patients had no documented intrahepatic progression at the time of last imaging follow-up. Nine patients developed extrahepatic progression at a mean time of 6.3 months and a median time of 6 months, of whom four underwent additional surgical resection. Response to therapy was based on time of first intervention. Cumulative survival from time of diagnosis with use of Kaplan-Meier analysis was 81% at 1 year, 54% at 2 years, and 40% at 3 years. Median survival time was 20 months. Cumulative survival from initial chemoembolization was 67% at 1 year, 50% at 2 years, and 40% at 3 years, with a median survival time of 13 months. The thirty-day mortality rate was zero.

CONCLUSION

Durable tumor response with chemoembolization is possible in this form of metastatic disease, which is highly resistant to systemic chemotherapy.

Failure of endovascular abdominal aortic aneurysm graft limbs

OBJECTIVE

Endovascular abdominal aortic aneurysm (AAA) grafts are subject to subsequent failure of endograft limbs. We sought to determine what device-related factors could be identified that might contribute to limb failure.

METHODS

We reviewed the records of patients who had undergone endovascular AAA repair and femorofemoral bypass grafting at a single institution.

RESULTS

Endovascular AAA repair was performed in 173 patients. There were 137 bifurcated endografts and 36 aortomonoiliac grafts combined with femorofemoral bypass grafts, yielding a total population of 310 aortic graft limbs and 36 femorofemoral grafts. Thirty-nine additional patients underwent femorofemoral bypass grafting for occlusive disease. The cumulative primary patency of all endografts performed for AAA was 92% at 21 months. Secondary patency was achieved for all failed endograft limbs. There were 24 aortic graft limb "failures" that required intervention: seven limbs underwent thrombosis requiring revision; kinked limbs requiring stenting either at the time of graft placement (17) or subsequently (7) were identified. Fully supported endograft limbs had better primary patency (97% at 18 months) than unsupported limbs (69% at 18 months, P <.001). The aortomonoiliac grafts with femorofemoral bypass grafts tended to have better patency (97% at 18 months) than bifurcated endografts (90% at 18 months), but this did not reach statistical significance (P =.28, not significant). Femorofemoral grafts performed for occlusive disease were found to have somewhat lower patency than those performed for AAA (83% vs 92% at 18 months of follow-up, P =.37, not significant).

CONCLUSIONS

Fully supported AAA endografts provide superior endograft limb patency compared with unsupported designs. Consideration should be given to routine stenting of all unsupported endograft limbs. Aortomonoiliac grafts and bifurcated grafts provide similar results for endograft limb patency. Femorofemoral bypass grafts performed in conjunction with aortomonoiliac grafts for AAA disease provide excellent short-term patency.

Gender-related differences in infrarenal aortic aneurysm morphologic features: issues relevant to Ancure and Talent endografts

PURPOSE

The purpose of this study was to determine whether gender-related anatomic variables may reduce applicability of aortic endografting in women.

METHODS

Data on all patients evaluated at our institution for endovascular repair of their abdominal aortic aneurysm were collected prospectively. Ancure (Endovascular Technologies (EVT)/Guidant Corporation, Menlo Park, Calif) and Talent (World Medical/Medtronic Corporation, Sunrise, Fla) endografts were used. Preoperative imaging included contrast-enhanced computed tomography and arteriography or magnetic resonance angiography.

RESULTS

One hundred forty-one patients were evaluated (April 1998-December 1999), 19 women (13.5%) and 122 men (86.5%). Unsuitable anatomy resulted in rejection of 63.2% of the women versus only 33.6% of the men (P = .026). Maximum aneurysm diameter in women and men were similar (women, 56.94 +/- 8.23 mm; men, 59.29 +/- 13.22 mm; P = .5). The incidence of iliac artery tortuosity was similar across gender (women, 36.8%; men, 54.9%; P = .2). The narrowest diameter of the larger external iliac artery in women was significantly smaller (7.29 +/- 2.37 mm) than in men (8.62 +/- 2.07 mm; P = .02). The proximal neck length was significantly shorter in women (10.79 +/- 12.5 mm) than in men (20.47 +/- 19.5 mm; P = .02). The proximal neck width was significantly wider in women (30.5 +/- 2.4 mm) than in men (27.5 +/- 2.5 mm; P = .013). Proximal neck angulation (>60 degrees) was seen in a significantly higher proportion of women (21%) than men (3.3%; P = .012). Of the patients accepted for endografting, a significantly higher proportion of women required an iliofemoral conduit for access (women, 28.6%; men, 1.2%; P = .016).

CONCLUSION

Gender-related differences in infrarenal aortic aneurysm morphologic features may preclude widespread applicability of aortic endografting in women, as seen by our experience with the Ancure and Talent devices. In addition to a significantly reduced iliac artery size, women are more likely to have a shorter, more dilated, more angulated proximal aortic neck.

Aneurysm sac pressure measurements after endovascular repair of abdominal aortic aneurysms

OBJECTIVES

The goal of endovascular grafting of abdominal aortic aneurysms (AAAs) is to exclude the aneurysm sac from systemic pressure and thereby decrease the risk of rupture. Unlike conventional open surgery, branch vessels in the sac (eg, lumbar artery and inferior mesenteric artery [IMA]) are not ligated and can potentially transmit pressure. The purpose of our investigation was to evaluate the feasibility of various interventional techniques for measuring pressure within the aneurysm sac in patients who had undergone endovascular repair of AAAs.

METHODS

Sac pressure measurements were performed in 21 patients who had undergone stent graft repair of AAAs. Seventeen of 21 patients had endoleaks demonstrated on 30-day computed tomographic (CT) scans. Access to the aneurysm sac in these patients was through direct translumbar sac puncture (5 patients), through a patent IMA accessed via the superior mesenteric artery (SMA) (9 patients), or by direct cannulation around attachment sites (3 patients). Four patients had perioperative pressure measurements obtained through catheters positioned along side of the endovascular graft at the time of its deployment. Two of these catheters were left in position for 30 hours during which time CT and conventional angiography were performed. Pressures were determined with standard arterial-line pressure transduction techniques and compared with systemic pressure in each patient.

RESULTS

Elevated sac pressure was found in all patients. The sac pressure in patients with endoleaks was found to be systemic (15 patients) or near systemic (2 patients) and all had pulsatile waveforms. Elevated sac pressures were also found in patients without CT or angiographic evidence of endoleak (2 patients). Injection of the sacs in two of these patients revealed a patent lumbar artery and an IMA.

CONCLUSIONS

It is possible to measure pressures from within the aneurysm sac in patients with stent grafts with a variety of techniques. Patients may continue to have pressurized AAA sacs despite endovascular AAA repair. Endoleaks transmit pulsatile pressure into the aneurysm sac regardless of the type. It is possible to have systemic sac pressures without evidence of endoleaks on CT or angiography.

Limb kinking in supported and unsupported abdominal aortic stent-grafts

PURPOSE

The occurrence of kinking of stent-graft limbs depends on the patient's anatomy and the device used. The purpose of this investigation was to determine the rates of limb kinking in supported and unsupported aortic stent-grafts.

MATERIALS AND METHODS

The authors performed a retrospective review of patients undergoing placement of either a Guidant Ancure/EGS or Medtronic Talent aortic stent-graft for the treatment of abdominal aortic aneurysm as part of separate phase II and phase III clinical trials. The records of 91 consecutive patients with 149 limbs were reviewed. The type and configuration of each device and any procedure performed specifically relating to limb patency was recorded. An analysis was then performed comparing the rates of kinking in supported and unsupported groups. A review of the literature was also performed.

RESULTS

Overall, there was kinking in 18 of 149 limbs (12%). In the supported stent-graft group, 48 bifurcated and 26 aortomonoiliac grafts were placed, with a total of 122 limbs at risk. Six limbs (5%) in five patients required intervention as a result of limb kinking. Stents were placed intraoperatively in two limbs (2%) and postoperatively in four limbs (3%) for thrombosis or severe stenosis. In the unsupported group, 12 bifurcated and three aortomonoiliac grafts were placed, with a total of 27 limbs at risk. Twelve limbs (44%) in eight patients required some type of intervention as a result of limb kinking. Stents were placed intraoperatively in seven limbs (26%) and postoperatively in five limbs (19%) for thrombosis or severe stenosis. Rates of limb kinking were significantly different between the supported and unsupported groups (P < .0001).

CONCLUSIONS

The use of supported versus unsupported stent-grafts impacts the occurrence of limb kinking. A direct comparison of the groups suggests that an unsupported stent-graft will be more than 15 times more likely than a supported system to require intervention because of kinking.

Relationship between preoperative patency of the inferior mesenteric artery and subsequent occurrence of type II endoleak in patients undergoing endovascular repair of abdominal aortic aneurysms

OBJECTIVES

The purpose of this study was (1) to find out whether preoperative inferior mesenteric artery (IMA) patency (on radiographic imaging) predicts IMA-related endoleaks after endovascular repair of infrarenal abdominal aortic aneurysms, (2) to determine feasibility of measuring aneurysm sac pressures in patients with endoleaks, and (3) to report early evidence of effective endovascular obliteration of IMA endoleaks.

METHODS

We studied 76 consecutive cases of infrarenal aortic aneurysms that were repaired with an endovascular approach (March 1998-April 1999).

RESULTS

There were 13 (17%) endoleaks persistent 30 days after the procedure. Eleven (85%) of these 13 were IMA-related endoleaks, which were documented with selective superior mesenteric artery angiography. The preoperative finding (on computed tomographic scan) of a patent IMA does not always predict an IMA-related endoleak, but results in a statistically and clinically significant higher ratio of patients with IMA-related endoleaks in the immediate postoperative period (24% versus 3%, P <.035). In eight of the 11 patients with persistent IMA-related endoleaks, measurement of intra-aneurysm sac pressures was possible, and six of these patients had systemic pressures within the excluded aneurysm sac. Nine (82%) of 11 IMA-related endoleaks were successfully obliterated by means of selective IMA embolization.

CONCLUSIONS

Many endoleaks are caused by a patent IMA, and this can result in persistence of systemic pressure within the aneurysm sac. The preoperative finding (on computed tomographic scan) of a patent IMA is a predictor of increased rates of IMA endoleaks, and IMA endoleaks can be successfully obliterated through endovascular procedures, after endovascular abdominal aortic aneurysm repair.

Diagnosis and treatment of inferior mesenteric arterial endoleaks after endovascular repair of abdominal aortic aneurysms

PURPOSE

To review the incidence and repair of inferior mesenteric arterial (IMA) type II endoleaks after endovascular repair of abdominal aortic aneurysms.

MATERIALS AND METHODS

Fifty patients who underwent endovascular repair of abdominal aortic aneurysms were examined. If an endoleak was identified at 30-day postoperative computed tomography, conventional arteriography was performed to identify and eliminate its source. After the exclusion of attachment site leaks, a catheter was placed selectively in the superior mesenteric artery (SMA). If retrograde filling of the IMA and aneurysm was identified, coil embolization was attempted through the SMA and middle colic artery. Intrasac pressures were measured at embolization.

RESULTS

Eight of 50 patients (16%) had type II endoleaks that were attributed to retrograde flow in the IMA. Intrasac measurements demonstrated systemic pressure in six patients and one-half systemic pressure in two patients. The IMA was embolized through the SMA and left colic artery in seven patients and through the translumbar aorta in one patient.

CONCLUSION

Retrograde flow in the IMA is responsible for many type II endoleaks. Systemic pressures are transmitted into the aneurysm sac from the IMA. The IMA can be embolized successfully with an SMA approach in most patients.

Perigraft air, fever, and leukocytosis after endovascular repair of abdominal aortic aneurysms

BACKGROUND

The postimplantation syndrome of fever and leukocytosis after endovascular repair of infrarenal aortic aneurysms has not been previously characterized and its etiology is not known.

METHODS

We studied the first 12 patients who underwent successful endovascular repair of infrarenal aortic aneurysms with Dacron-covered stent-grafts, as part of an ongoing phase II clinical trial. Sepsis syndrome evaluations (physical examination, urinalysis, chest radiograph, urine cultures, and blood cultures) were performed for all patients with postoperative temperature (T) greater than 101.4 degrees F. Computed tomography scans of the abdomen were performed, as part of the clinical protocol, on postoperative days 2 and 30.

RESULTS

Fever (T > 101.4 degrees F) was seen in 8 of 12 (67%) patients (P < 05). An additional 2 of 12 (17%) patients had low-grade fevers (100.3 degrees F, 100.6 degrees F). Only 2 of 12 (17%) patients remained afebrile postoperatively. Leukocytosis with counts over 11,000 white blood cells (WBC)/dL was observed in 7 of 12 (58%) patients (P < 05). Sepsis evaluations failed to identify any source of infection in 11 of 12 (97%) patients. Computed tomography scan evidence of perigraft air was noted in 8 of 12 (67%) patients. All patients were afebrile, had normal white blood cell counts, and were discharged within 1 week postoperatively. There has been no evidence of graft infection after 1 to 6 months of follow-up.

CONCLUSIONS

Fever and leukocytosis after stent-graft repair of aortic aneurysms does not represent evidence of systemic or graft infection and is not clearly related to nonspecific causes of postoperative fever and leukocytosis. Moreover, the finding of early postoperative perigraft air is not necessarily an indication of graft infection even when concurrently present with fever and leukocytosis.

Chemoembolization of hepatocellular carcinoma with cisplatin, doxorubicin, mitomycin-C, ethiodol, and polyvinyl alcohol: prospective evaluation of response and survival in a U.S. population

PURPOSE

To evaluate response and survival after hepatic chemoembolization with cisplatin, doxorubicin, mitomycin-C, Ethiodol, and polyvinyl alcohol in a U.S. population of patients with hepatocellular carcinoma.

MATERIALS AND METHODS

Thirty-eight consecutive patients were treated: 35% stage I, 62% stage II, 3% stage III. Fifty-one percent had cirrhosis. Chemoembolization was performed at approximately monthly intervals for one to seven sessions (mean, 2.2). Pretreatment and posttreatment cross-sectional imaging and alpha-fetoprotein (AFP) levels were obtained prospectively 1 month after treatment and then every 3 months. Thirty-day response was calculated by means of the the World Health Organization/Eastern Cooperative Oncology Group criteria.

RESULTS

One patient was lost to follow-up. In seven patients, lesions became resectable after chemoembolization. Among 13 evaluable patients with initially elevated AFP level, 70% had a partial biologic response (>50% decrease in AFP), 15% had a minor response (25-50% decrease), and the remaining 15% remained stable. Among 25 patients evaluable for morphologic response, 36% had a partial response, 32% had a minor response, and 32% remained stable. No patients had progression of disease while receiving therapy. The cumulative survival was 60% at 1 year, 41% at 2 years, and 16% at 3 years. Two patients developed progressive hepatic failure. Thirty-day mortality was 3% (one patient).

CONCLUSION

These results compare favorably to published response and survival data for chemoembolization of advanced hepatocellular carcinoma from Asia and Europe.

Renal artery stenosis: evaluation with conventional angiography versus gadolinium-enhanced MR angiography

PURPOSE

To evaluate the interobserver and intermodality variability of conventional angiography and gadolinium-enhanced magnetic resonance (MR) angiography in the assessment of renal artery stenosis.

MATERIALS AND METHODS

Fifty-four patients underwent conventional angiography and gadolinium-enhanced three-dimensional gradient-echo MR angiography. Three angiographers blinded to each other's interpretations and the MR angiographic findings assessed the conventional angiograms for renal artery stenosis. Similarly, three blinded MR imagers evaluated the MR angiograms.

RESULTS

Interobserver variability for the degree of renal artery stenosis in the 107 kidneys evaluated was not significantly different between the two modalities. The mean SD of the degree of stenosis was 6.9% at MR angiography versus 7.5% at conventional angiography (alpha < or = .05, P > .05). In 70 kidneys (65%), the average degree of stenosis reported by the readers for the two modalities differed by 10% or less. In 22 cases (21%), the degree of stenosis was overestimated with MR angiography by more than 10% relative to the results of conventional angiography. In 15 cases (14%), the degree of stenosis was underestimated with MR angiography by more than 10%.

CONCLUSION

Gadolinium-enhanced MR angiography permits evaluation of renal artery stenosis with an interobserver variability comparable with that of conventional angiography.

Endovascular surgery based solely on noninvasive preprocedural imaging

PURPOSE

Conventional pre-endovascular procedural evaluation uses both noninvasive testing and diagnostic arteriography. Diagnostic and therapeutic procedures often must be performed separately because of concerns about excessive contrast administration or inappropriate location of vascular access for the interventional procedure. We wanted to determine if patients could successfully undergo endovascular procedures based on noninvasive modalities alone.

METHODS

One hundred nineteen consecutive patients requiring intervention for lower-extremity ischemia were evaluated by means of physical examinations and segmental pressure measurements. Patients then underwent magnetic resonance angiography (MRA) to image native vessels or duplex scanning for failing bypass grafts. Suitable patients underwent endovascular procedures with "road map" arteriography, which was compared with preoperative duplex scanning or MRA findings. Costs of the conventional and noninvasive approaches were compared, on the basis of estimated hospital cost schedule.

RESULTS

Sixty consecutive endovascular procedures were performed in 56 patients (105 lesions angioplastied), either alone (30, 50%) or in combination (30, 50%) with another vascular reconstruction. Completely noninvasive evaluation was accomplished in 43 procedures (72%), either by means of duplex scanning (11, 18%) or MRA (32, 53%). Conventional arteriography (CA) was required in 2 patients (3%) because of MRA contraindications and in 1 patient because of complex previous arterial reconstruction. Fourteen patients had earlier CAs. The findings of the noninvasive modalities were confirmed in every case by means of intraoperative arteriography, and no additional lesions were revealed (no false positive or negative studies). After endovascular interventions, the mean patient ankle-brachial index (ABI) improved from 0.64 +/- 0.03 to 0.81 +/- 0.03 (P <.001) and the mean limb-status category improved from 3.4 +/- 0.2 to 0.8 +/- 0.2 (P <.001). There were 4 initial technical failures (7%), 1 morbidity (1%), and no mortalities. The noninvasive approach was less costly than if preprocedural diagnostic CA had been used, allowing $551 saved for each duplex scanning case and $235 saved for each MRA case. If the cost of a short-stay unit after a diagnostic arteriogram was included, the savings were greater: $695 saved for each duplex scanning case and $379 saved for each MRA case.

CONCLUSION

Endovascular procedures can be performed based on preprocedural noninvasive modalities alone. For patients requiring endovascular procedures, knowledge of the arterial anatomy before obtaining arterial access avoids the need for additional punctures or sessions (eg, antegrade puncture for femoral angioplasty after retrograde puncture for the diagnostic arteriogram). This approach is less costly than performing preprocedural diagnostic arteriography and avoids the hazards of arterial puncture and nephrotoxic contrast agents.

Direct percutaneous jejunostomy: techniques and applications--ten years experience

PURPOSE

To present 10 years experience with direct fluoroscopically guided percutaneous jejunostomy.

MATERIALS AND METHODS

Percutaneous jejunostomy was performed in 62 patients, most of whom had undergone major abdominal surgery. A new or replacement jejunostomy was created for alimentation in 20 and 21 patients, respectively. Jejunostomy was performed for interventional procedures of the bile ducts or intestine in 13 patients and for retrograde gastroesophageal drainage in eight. The distended jejunum was accessed with a 21-gauge needle, immobilized with a gastric anchor, and catheterized with a 10-14-F locking loop drain.

RESULTS

The technical success rate was 19 of 20 (95%) for new feeding jejunostomy and 17 of 21 (81%) for replacement feeding jejunostomy. Jejunostomy facilitated drainage, dilation, stone extraction, and recanalization in the bile ducts or intestine in all 13 patients. Retrograde jejunoesophagogastrostomy suction effectively replaced painful nasogastric suction in all eight patients. Two patients who underwent replacement jejunostomy required laparotomy for possible leakage; there was no important procedure-related morbidity and no procedure-related mortality.

CONCLUSION

The technical success and complication rates of feeding percutaneous jejunostomy compare favorably with those of surgery or endoscopy. Percutaneous jejunostomy is a useful and underused approach to managing bowel and biliary obstruction.

Magnetic resonance angiography of lower-extremity arterial disease

Improvements in vascular technique have expanded the treatment options for patients with severe occlusive peripheral vascular disease. The decision to perform a major revascularization procedure in patients who are often at high risk for cardiovascular morbidity and mortality depends on the risk-benefit ratio. Detailed and accurate vascular imaging is essential and evaluating the likelihood of a successful revascularization with subsequent limb salvage. Although contrast angiography has been the time-honored reference standard imaging technique, the method is an invasive procedure with limitations and risks. MRA is a new, noninvasive vascular imaging technique that may now be added to the imaging options with the potential for improved sensitivity for finding patent runoff vessels, avoidance of morbidity, and cost equivalent to that of conventional contrast angiography. Magnetic resonance angiography is a rapidly developing and exciting new vascular imaging technique. As with any new technique, it is imperative that individual centers validate their MRA results and interpretations against the time-honored standard, which continues to be contrast arteriography. Several studies now indicate that MRA can be a cost-effective outpatient imaging technique sufficient for planning and successfully performing peripheral bypass procedures. As developments in hardware, software, and non-nephrotoxic contrast agents continue to increase, applicability of MRA in vascular surgery will continue to expand. Predictably, MRA will have a major role in the future of vascular imaging, and it is likely to supplant the need for conventional contrast angiography in the majority of patients.

Replacement of failing tunneled hemodialysis catheters through pre-existing subcutaneous tunnels: a comparison of catheter function and infection rates for de novo placements and over-the-wire exchanges

PURPOSE

Tunneled hemodialysis catheter dysfunction often occurs from fibrin sheath formation. As a way to preserve existing catheter venous access sites, the authors evaluated over-the-wire exchange of catheters through pre-existing subcutaneous tunnels as an alternative to catheter removal and de novo catheter replacement.

PATIENTS AND METHODS

One hundred nineteen catheters were placed in 68 patients. Seventy-seven catheters were placed de novo and 42 catheters were placed through the pre-existing subcutaneous tunnels of failing catheters. Technical success, short-term complications, infection rates, and functional catheter longevity were evaluated.

RESULTS

Technical success for catheter exchange was 93%. Infection rates were comparable to those of de novo catheter placement: 0.15 and 0.11 infections per 100 catheter days for de novo and exchanged catheters, respectively. Catheter duration of function was not significantly different for de novo versus exchanged catheters: 63% and 51% at 3 months, 51% and 37% at 6 months, and 35% and 30% at 12 months, respectively.

CONCLUSIONS

Over-the-wire exchange of tunneled hemodialysis catheters is safe and easily performed. It causes no increase in infectious complications and provides similar catheter longevity to de novo catheter placement. The procedure is an important option for prolonging tunneled hemodialysis catheter access sites.

Percutaneous varicocele embolization versus surgical ligation for the treatment of infertility: changes in seminal parameters and pregnancy outcomes

PURPOSE

To compare the success of percutaneous varicocele embolization to surgical ligation with regard to changes in semen characteristics and pregnancy outcome.

MATERIALS AND METHODS

Infertility records from 346 men who underwent correction of their varicocele for infertility (surgical ligation 149; embolization 197) were reviewed retrospectively. Preprocedural and postprocedural semen analyses and pregnancy outcomes were obtained with use of chart and telephone follow-up.

RESULTS

In men who successfully impregnated their partners, there were significant improvements in sperm density, percent total improvement, motility, and progression. Postprocedural (embolization vs surgery) percentage increases in seminal parameters were density, 156.8% versus 138.5%; total, 168.8% versus 157.91%; and motility, 2.7% versus 3.2%. The percent of individuals who had a change in sperm progression was 31% versus 41%. There was no statistical difference between the techniques based on t tests. The pregnancy rates were similar for the two groups, 39% and 34% for embolization and surgery, respectively.

CONCLUSION

There is no significant statistical difference in seminal values or pregnancy outcome between the two techniques.

Mechanical declotting of thrombosed dialysis grafts: experience in 86 cases

PURPOSE

To evaluate the efficacy, safety, and primary patency of percutaneous mechanical declotting of thrombosed dialysis grafts using latex balloons.

MATERIALS AND METHODS

Fifty-nine patients with 86 episodes of dialysis graft thrombosis underwent percutaneous mechanical declotting with balloons using crossing catheter or transjugular technique. Vital signs, peripheral oxygenation, technical success, procedure time, and complications were recorded prospectively. Technical success was defined as a patent graft at the completion of the procedure. Clinical success, defined as successful dialysis for 1 week, and primary patency were obtained retrospectively from review of the dialysis records.

RESULTS

Technical success was achieved in 74 of 86 procedures (86%). Median procedure time was 115 minutes, including failed cases. Ten of the 12 technical failures were due to resistant vascular stenoses precluding graft patency, despite removal of thrombus. There were no immediate complications. One patient died of sepsis 4 days after declotting. Clinical success was achieved after 65 of 86 procedures (76%); nine grafts thrombosed within 1 week of a technically successful declotting procedure. Primary patency (including technical failures) was 37% at 3 months, 31% at 6 months, and 17% at 12 months.

CONCLUSION

Mechanical declotting is an effective means of restoring patency to thrombosed dialysis grafts.

Safety of decreasing bedrest after coronary angiography

This study was designed to assess the safety of allowing patients to ambulate after 2 hr of bedrest following coronary angiography. A total of 205 patients were randomized to either 2 or 4 hr of bedrest following hemostasis after angiography utilizing five, six, or seven French catheters. The primary endpoint was defined as bleeding requiring recompression and additional bedrest. No significant difference was demonstrated overall between the two groups with respect to rebleeding or hematoma formation when the angiogram was performed using five or six French catheters. However, the use of seven French catheters resulted in a significantly higher rebleeding rate in the 2-hr group compared to the 4-hr population. The findings of this study suggest that 2 hr of bedrest following angiography utilizing five or six French catheters is adequate to obtain hemostasis safely in the majority of patients, whereas 4 hr is suggested when seven French catheters are utilized.

Balloon occlusion portography to diagnose new-onset left hepatic vein thrombosis and widening of an existing Wallstent TIPS by Palmaz stents for recurrent portal hypertension and variceal bleeding

A 31-year-old man with Child's class A micronodular cirrhosis, left lobe hypertrophy, and a transjugular intrahepatic portosystemic shunt (TIPS) which had been placed 6 months earlier, was admitted for recurrent esophageal bleeding and a portosystemic gradient of 42 mmHg. Balloon occlusion portography documented unsuspected ostial thrombosis of the previously patent left hepatic vein. This was considered the cause of the pressure rise. As it was not possible to insert a second TIPS in parallel, the shunt, stented originally with 10-mm Wallstents, was overdilated to 12 mm, and two 12-mm Palmaz stents were placed coaxially, reducing the portosystemic pressure gradient to 13 mmHg.

Transvenous removal of fibrin sheaths from tunneled hemodialysis catheters

PURPOSE

Long-term hemodialysis catheters are prone to significant dysfunction due to fibrin accumulation around their tips. The authors assessed the efficacy of transvenous snare removal of fibrin to prolong function of these catheters.

PATIENTS AND METHODS

Twenty-four procedures were performed in 20 patients with tunneled hemodialysis central venous catheters. Technical success was gauged by venography and the ability to infuse and aspirate catheters. Durable efficacy was assessed by improvement in hemodialysis.

RESULTS

Twenty-two of 24 procedures were performed successfully. In two cases residual material remained despite repeated stripping. Mean preprocedure hemodialysis blood-liters processed per hour increased from 15.1 to 19.1 L/h in the first dialysis session after stripping, and blood flow rates of 300 mL/min or greater were restored. By the fifth dialysis session after stripping, the blood-liters processed per hour dropped to 15.9 L/h as catheter flow rates returned to unacceptable levels.

CONCLUSIONS

Percutaneous fibrin removal with a loop snare provides no durable benefit in improving function of failing hemodialysis catheters.

The fate of bypass grafts to angiographically occult runoff vessels detected by magnetic resonance angiography

PURPOSE

Magnetic resonance angiography (MRA) is a noninvasive vascular imaging technique that is more sensitive than contrast arteriography (CA) for the detection of patent distal runoff vessels. This technique has facilitated performance of MRA-directed bypass procedures for patients who were believed not to be bypass candidates because of the absence of a suitable target vessel on the preoperative CA. The fate of bypasses to these angiographically occult runoff vessels is unknown, however, and it has been proposed that patients with angiographically occult runoff may have aggressive occlusive disease, rendering bypass procedures ultimately futile.

METHODS

Between April 1992 and February 1995, 212 autogenous vein infrageniculate bypasses were performed for limb-salvage indications, 22 (12%) to angiographically occult runoff vessels. Results of bypasses performed to angiographically occult vessels were compared with those of bypasses to CA-detected runoff vessels. Life-table analysis of graft-patency and limb-salvage rates was performed.

RESULTS

The accuracy of the MRA-predicted patency of angiographically occult vessels was confirmed in every case by the operative findings. Life-table analysis revealed no significant difference in primary graft patency (p > 0.05) or limb-salvage (p > 0.05) rates between patients with bypasses to runoff vessels seen by MRA alone. At 35 months after surgery, the primary graft patency rate was 68% for bypasses to CA-detected vessel bypass and 67% for MRA-detected vessels. The limb salvage rate was 83% for CA-detected vessel bypass patients and 78% for patients with angiographically occult runoff.

CONCLUSIONS

MRA can accurately identify patent runoff vessels not visualized by CA. Results of bypasses performed to angiographically occult runoff vessels are similar to those of bypasses performed to vessels detected by CA. MRA should be performed in patients in whom CA fails to reveal runoff vessels suitable for use in a limb-salvage procedure. The greater sensitivity of MRA may facilitate successful bypass surgery and improve the overall limb-salvage rate.

Temporary use of a Bird's Nest filter during iliocaval thrombolysis

A jugular Bird's Nest filter (Cook, Bloomington, Ind) was partially deployed in the suprarenal cava for prophylaxis to prevent pulmonary embolism in a young woman with phlegmasia cerulea dolens. It was effective in capturing large emboli during thrombolysis of a loose iliocaval thrombus. It was safely removed 6 1/2 hours later, after lysis of most retained filter clots.

Transjugular intrahepatic portosystemic shunt-related arterial injuries: prospective comparison of large- and small-gauge needle systems

PURPOSE

The authors prospectively compared the nature and incidence of hepatic arterial injuries resulting from creation of a transjugular intrahepatic portosystemic shunt (TIPS) with large- and small-gauge needle systems.

PATIENTS AND METHODS

Fifty patients underwent hepatic and superior mesenteric angiography immediately before and after shunt creation. A sheathed 16-gauge needle system was used to locate and puncture the portal vein in 24 patients. A 21-gauge needle system was used in 26 patients.

RESULTS

Shunts were successfully created in all patients. Three inadvertent hepatic arterial punctures were recognized during shunt placement, two with the small needle and one with the large needle system. No hepatic arterial lesions were detected in any patient. Two incidental hepatomas were identified at angiography.

CONCLUSION

TIPS-related hepatic arterial injuries are rare. In this series, large and small needle systems were indistinguishable with respect to this complication.

Magnetic resonance angiography of the distal lower extremity

OBJECTIVE

To assess magnetic resonance angiography (MRA) for demonstration of arterial patency in the ankle and foot of patients with peripheral vascular disease.

METHODS

Peripheral MRA of the ankle and foot was performed on 34 limbs of 31 insulin-dependent diabetics. 2-D time-of-flight MRA (TR 33 ms/TE 7.7 ms/inferior saturation band) was performed with 16 cm field of view. Pre- or intra-operative angiographic correlation was available in all cases.

RESULTS

In 24 limbs MRA was compared to conventional angiography. MRA showed more patient run-off vessel segments (120) than angiography (100). In 10 limbs MRA was compared to intraoperative angiography and for the detection of patent vessel segments showed a sensitivity of 87.5% (42/48) with a 95% confidence interval of 75% to 95% and a specificity of 95% (38/40) with a 95% confidence interval of 83% to 99%. Pitfalls included difficulty in visualizing flow at the bifurcation of the peroneal artery, in the plantar arch and retrograde flow in the lateral plantar artery.

CONCLUSIONS

MRA is sensitive for the detection of patent arteries in the ankle and foot but artefacts may cause overdiagnosis of focal stenoses or occlusions.

Multicenter trial to evaluate vascular magnetic resonance angiography of the lower extremity. American College of Radiology Rapid Technology Assessment Group

OBJECTIVES

To assess the value of magnetic resonance angiography (MRA) in presurgical evaluation of patients with severe lower limb atherosclerotic occlusive disease and to assess the feasibility of rapidly conducting rigorous technology assessment.

DESIGN

Blinded, prospective study of consecutive patients with signs or symptoms of severe infrainguinal peripheral vascular disease who were candidates for percutaneous or surgical intervention. Using both descriptive statistics and multivariate logistic analyses, MRA was compared with contrast arteriography (CA) (the current technique) for imaging 15 arterial segments of the leg and foot. Intraoperative contrast angiography was the "gold" standard. Also studied was the effect of adding MRA to the information used in planning treatment.

SETTING

Six US hospitals, one a community hospital.

PATIENTS

A total of 155; 84% with either rest pain or tissue loss.

RESULTS

Sensitivity in distinguishing patent segments from completely occluded segments was 83% for CA and 85% for MRA; both had 81% specificity. For distinguishing near-normal segments (suitable as bypass graft termini), CA was less sensitive than MRA (77% vs 82%), but more specific (92% vs 84%). After adjusting for same-reader effects, odds of correctly distinguishing patent segments were 1.6 times as great for MRA as for CA (P < .01); for distinguishing near-normal segments, the odds for CA were 1.5 times as great as for MRA (P < .05). The addition of MRA changed the treatment plan in 13% of patients; in 86% of these cases, the surgery actually performed indicated that the MRA-inclusive plan was superior.

CONCLUSIONS

Individually, MRA and CA are approximately equivalent in diagnostic accuracy. The addition of MRA to treatment plans based only on CA and other diagnostic information clearly improves the plans. Completed in 15 months (as planned), our study demonstrates the feasibility of conducting rigorous technology assessment rapidly enough to be timely even in fields in which diagnostic and treatment techniques are rapidly changing.

Intentional reversible thrombosis of transjugular intrahepatic portosystemic shunts

PURPOSE

To assess whether balloon occlusion of a transjugular intrahepatic portosystemic shunt (TIPS) will allow permanent yet reversible shunt thrombosis.

MATERIALS AND METHODS

A balloon catheter was inflated in the midportion of the TIPS in two women with severe, uncontrollable encephalopathy or liver failure (aged 42 and 65 years, respectively) to allow occlusive thrombus to develop below the balloon.

RESULTS

Balloon occlusion led to rapid TIPS thrombosis, which was readily reversible.

CONCLUSION

Balloon thrombosis is a simple technique for complete occlusion of a TIPS. This technique may also be useful for occlusion of surgical mesocaval H-graft shunts or dialysis access shunts.

Cost-effectiveness of MR angiography in cases of limb-threatening peripheral vascular disease

PURPOSE

To evaluate the cost-effectiveness of magnetic resonance (MR) angiography in the preoperative planning of treatment in patients with limb-threatening peripheral vascular disease (PVD).

MATERIALS AND METHODS

A decision model was developed to study the effects of MR angiography on the outcome and cost of treatment. The authors calculated the incremental cost per quality-adjusted life-years gained (ie, cost-effectiveness ratio) when conventional angiography was replaced or supplemented with MR angiography. Previously reported data regarding the accuracies of MR and conventional angiography were used in the analysis.

RESULTS

The cost-effectiveness ratio of MR angiography ranged from negative (cost-reducing) values to $78,000. For the base case in which the sensitivity and specificity of MR angiography for the evaluation of inflow vessels were 92% and 88% and those of conventional angiography were 97% and 97%, respectively, the cost-effectiveness ratio was $25,895.

CONCLUSION

MR angiography may be a cost-effective alternative to conventional angiography in patients with limb-threatening PVD if its accuracy for the inflow evaluation reaches certain thresholds. Further prospective investigation is warranted.

Peripheral vascular surgery with magnetic resonance angiography as the sole preoperative imaging modality

PURPOSE

Magnetic resonance angiography (MRA) is a developing technique that provides arteriograms without the risks associated with iodinated contrast and arterial puncture or the expense of hospitalization. Prior reports have demonstrated the accuracy of peripheral vessel MRA for evaluation of the aorta through pedal vessels. This study sought to determine whether vascular reconstructions could be planned and accomplished on the basis of MRA alone.

METHODS

Eighty consecutive candidates for bypass with ischemic rest pain or tissue loss were studied with preoperative outpatient MRA of the juxtarenal aorta through the foot. Confirmation of MRA findings was provided by intraoperative intraarterial pressure measurements for proximal vessels and postbypass arteriography for the runoff. Life-table analysis of graft patency and limb salvage was performed.

RESULTS

Two patients could not tolerate MRA and required contrast arteriography, but all others underwent reconstructive procedures on the basis of MRA alone (11 aortobifemoral, 67 infrainguinal). Intraoperative findings regarding suitability of inflow and outflow vessels confirmed the accuracy of the MRAs in every case. MRA indicated that none of the patients undergoing infrainguinal bypass had significant inflow occlusive disease, and this was confirmed at operation with pressure measurements of inflow vessels that were always within 10 mm Hg (peak systolic) of systemic pressure. The results of intraoperative completion arteriography and preoperative MRAs were identical for all but two patients who had minor discrepancies. All aortobifemoral reconstructions remained patent, and all limbs remained intact. The infrainguinal reconstructions had an 84% limb salvage rate and 78% primary graft patency rate at 21 months. Comparison of charges for patients undergoing preoperative MRA versus contrast angiography showed a cost savings of $1288 for each patient treated with preoperative MRA alone.

CONCLUSIONS

MRA is a noninvasive, cost-effective outpatient imaging technique that, if properly performed and interpreted, is sufficient for planning peripheral bypass procedures. Its use may supplant contrast arteriography in many patients.

Intracardiac thrombosis and antiphospholipid antibodies: a case report and review of the literature

A case report and review of the literature are reported concerning the relationship of intracardiac thrombosis and antiphospholipid antibody syndromes. Nine cases are identified, divided into three categories: three patients had antiphospholipid syndrome associated with systemic lupus erythematosus, three had primary antiphospholipid syndrome, and three had probable secondary antiphospholipid syndrome. All had intracardiac thrombosis. All patients were women, and the average age was 36 years. Although intracardiac thrombosis appears to be an unusual association with antiphospholipid antibody syndromes, young women with embolic events should be evaluated for antiphospholipid antibodies and intracardiac source of embolus.

Preliminary experience with magnetic resonance venography: comparison with findings at surgical exploration

While conventional magnetic resonance imaging has been described for the evaluation of the venous system, we have recently developed the technique of magnetic resonance venography (MRV), which generates three-dimensional projection venograms. Our purpose was to determine if MRV reliably images the venous system by comparison with findings at surgical exploration. Thirteen of fourteen consecutive patients undergoing bypass surgery (26 limbs) were studied by 2D time-of-flight MRV preoperatively from the inguinal ligament to the ankle bilaterally. The average examination time was 50 min. The size and quality of each saphenous vein were recorded at the saphenofemoral junction, mid-thigh, knee, mid-calf, and malleolus. Intraoperatively the quality and size of each vein were measured in situ and when distended by saline. Twelve veins were of good quality. MRV predicted this in every case. One vein, found to be recanalized, had an abnormally thick wall noted on MRV. MRV measurements of average vein size were intermediate between that of the in situ and distended vein and correlated most closely with the distended vein (R = 0.74, P < 0.001). The superficial and deep femoral veins and lesser saphenous veins were routinely visualized by MRV; thus a complete map of all available vein was obtained by a single study. It is concluded that MRV is an accurate method of venous imaging as confirmed by findings at operative exploration. This new technique holds promise as a noninvasive method for evaluation of the venous system and warrants further investigation.

Transjugular intrahepatic portosystemic shunt stenosis and revision: early and midterm results

OBJECTIVE

The purpose of this study was to define the pattern, rate, and interval during which stenosis develops in transjugular intrahepatic portosystemic shunts (TIPS) and to assess the effect of revision in prolonging shunt patency.

MATERIALS AND METHODS

TIPS were created in 100 patients during a 34-month period. Sixty-one shunt venograms were obtained in 38 consecutive patients between 1 and 24 months after TIPS placement. Eighteen patients were examined because of recurrent symptoms, and all 38 had routine follow-up.

RESULTS

Stenoses attributed to neointimal hyperplasia developed within both the TIPS stent and the outflow hepatic veins. Stenoses of greater than 50% developed in 12 patients within 6 months of TIPS placement. In addition to focal stenoses, the outflow hepatic veins diffusely shrank an average of 51% in diameter. Thirty-six shunt interventions were required: eleven balloon dilatations and 25 placements of an additional stent. Life-table analysis showed that patency of the primary shunt was 75% at 6 months, 50% at 1 year, and 32% at 2 years. The primary-assisted patency of the shunt was 85% at 12 months after shunt creation.

CONCLUSION

The results indicate that TIPS are prone to significant and frequent early stenosis, warranting follow-up within 3-6 months in all cases. Stenosis of the outflow hepatic vein is the most common cause of shunt malfunction. Revision of a shunt significantly prolongs shunt patency.

Evaluation of renal artery stenosis by magnetic resonance angiography

BACKGROUND

Accurate identification of patients with surgically correctable renovascular hypertension has been difficult by noninvasive means. Advances in the technique of magnetic resonance angiography (MRA) have begun to provide detailed, accurate imaging of the vascular system. This study reports our recent experience in the evaluation of the renal arteries by this technique.

METHODS

MRA and contrast arteriography were performed in 32 arteries (16 adult patients) for evaluation of hypertension, abdominal aortic aneurysm, mesenteric vascular disease, and aorto-iliac occlusive disease. Luminal diameter reduction (%) was determined from two-dimensional time-of-flight (TOF) axial images. Contrast arteriography served as the gold standard for comparison.

RESULTS

Contrast arteriography revealed a 50% or greater stenosis in 11 of 32 vessels studied (34%). As a screening test for detection of greater than 50% diameter reduction, MRA had a sensitivity of 91%, a negative predictive value of 94%, and an overall accuracy of 81%. Linear regression analysis demonstrated significant correlation between MRA and arteriographic measurements (r = 0.8; P < 0.001).

CONCLUSIONS

This study demonstrates the ability of MRA to accurately assess the main renal arteries for the presence of critical stenosis. This noninvasive evaluation compares well with conventional angiography and may have increasing application in the screening of patients with suspected renovascular disease.

Magnetic resonance angiography of the aorta, iliac, and femoral arteries

BACKGROUND

Successful management of patients with peripheral vascular disease requires detailed vascular imaging, usually performed by contrast arteriography. Recently, magnetic resonance angiography (MRA) has been shown to be a noninvasive technique with greater sensitivity than contrast arteriography for detecting distal runoff vessels in patients with peripheral arterial occlusive disease. However, to supplant the need for contrast arteriography and provide a completely noninvasive evaluation of patients with occlusive disease, accurate imaging of the inflow vessels and the runoff vessels is necessary.

METHODS

We used both conventional arteriography and MRA in preoperative studies of the aorta, iliac, and femoral vessels of 47 patients. Conventional arteriography and MRA studies were compared for their ability to detect vessel patency and the presence of hemodynamically significant stenoses. Independent interventional plans were developed based on the information provided by each technique. The findings of conventional and MRA studies were verified by intraoperative arteriography or direct operative exploration.

RESULTS

Results of the two studies were identical in 41 (87%) of 47 patients or 600 (98%) of 614 segments imaged. MRA accurately detected patent and occluded arterial segments (sensitivity 99.6%, specificity 100%, positive predictive value 100%, negative predictive value 98.6%) and hemodynamically significant stenoses. Therapeutic plans based on either MRA or conventional arteriography were identical for each patient.

CONCLUSIONS

MRA provides comparable results to contrast arteriography in the proximal arterial system and superior results for imaging the distal vasculature. This noninvasive technique may replace contrast arteriography in a large number of patients in the future.

Magnetic resonance angiographic imaging of angioplasty and atherectomy sites

Magnetic resonance angiography (MRA) provides detailed morphologic and flow information that demonstrates complex changes at sites of percutaneous transluminal angioplasty (PTA) and atherectomy. The purpose of this study is to examine the appearance of the vessel by MRA in the initial post-procedural and early follow-up periods.

METHODS

MRA was performed to evaluate 35 infrainguinal endovascular procedures (20 patients), including PTA (20), atherectomy (4), and combination PTA/atherectomy (11). MRA imaging was performed within 24 hours of the procedure and at a mean follow-up interval of 3.5 months (range 1-8).

RESULTS

Abnormalities in the immediate post-procedural MRA were seen in 55% of the PTA group and 93% of the atherectomy group (p = 0.04). Importantly, three of 35 lesions (9%) were shown by MRA to harbor > 50% stenoses despite angiographically "successful" procedures. Follow-up MRA showed abnormalities in 25% of those undergoing PTA, and in 67% of those with atherectomy (p = 0.01). At the time of follow-up MRA, four areas showed > 50% stenosis and four areas showed occlusion, revealing unfavorable outcomes in 22%.

CONCLUSIONS

MRA provides a detailed noninvasive image of the sites of endovascular interventions and reveals vessel wall abnormalities not appreciated by conventional arteriography. Continued observation may allow prediction of segments at increased risk for restenosis.