How to manage infected aortic endografts

Aortic endografts have become the preferred treatment for aneurysms of the descending thoracic aorta and the infrarenal aorta. The prevalence of endograft infections is about 0.6%, and with the growing number of patients with aortic endografts, the number of patients with endograft infections has also increased. It is important for physicians who treat aneurysmal disease with endografting to understand the pathophysiology, work-up, and treatment options available. Currently, the mainstay of treatment is prolonged antibiotic therapy, explant of all prosthetic material, and reconstruction of the vasculature with either an in situ or extra-anatomic bypass. However, there is a growing experience of less invasive treatment strategies that can be used in patients who cannot withstand an operation of this magnitude.

Structural MRI of carotid artery atherosclerotic lesion burden and characterization of hemispheric cerebral blood flow before and after carotid endarterectomy

Collateral circulation plays a major role in maintaining cerebral blood flow (CBF) in patients with internal carotid artery (ICA) stenosis. CBF can remain normal despite severe ICA stenosis, making the benefit of carotid endarterectomy (CEA) or stenting difficult to assess. Before and after surgery, we assessed CBF supplied through the ipsilateral (stenotic) or contralateral ICA individually with a novel hemisphere-selective arterial spin-labeling (ASL) perfusion MR technique. We further explored the relationship between CBF and ICA obstruction ratio (OR) acquired with a multislice black-blood imaging sequence. For patients with unilateral ICA stenosis (n = 19), conventional bilateral labeling did not reveal interhemispheric differences. With unilateral labeling, CBF in the middle cerebral artery (MCA) territory on the surgical side from the ipsilateral supply (53.7 +/- 3.3 ml/100 g/min) was lower than CBF in the contralateral MCA territory from the contralateral supply (58.5 +/- 2.7 ml/100 g/min), although not statistically significant (p = 0.09). The ipsilateral MCA territory received significant (p = 0.02) contralateral supply (7.0 +/- 2.7 ml/100 g/min), while ipsilateral supply to the contralateral side was not reciprocated. After surgery (n = 11), ipsilateral supply to the MCA territory increased from 57.3 +/- 5.7 to 67.3 +/- 5.4 ml/100 g/min (p = 0.03), and contralateral supply to the ipsilateral MCA territory decreased. The best predictor of increased CBF on the side of surgery was normalized presurgical ipsilateral supply (r(2) = 0.62, p = 0.004). OR was less predictive of change, although the change in normalized contralateral supply was negatively correlated with OR(excess) (=OR(ipsilateral) - OR(contralateral)) (r(2) = 0.58, p = 0.006). The results demonstrate the effect of carotid artery stenosis on blood supply to the cerebral hemispheres, as well as the relative role of collateral pathways before surgery and redistribution of blood flow through these pathways after surgery. Unilateral ASL may better predict hemodynamic surgical outcome (measured by improved perfusion) than ICA OR.

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.

Endovascular repair of aortic aneurysms: critical events and adjunctive procedures

OBJECTIVE

We sought to define the learning curve relative to the incidence and range of intraoperative problems and to establish guidelines for troubleshooting during the endovascular repair of infrarenal aortic aneurysms.

METHODS

We prospectively evaluated our first 75 consecutive cases over a 12-month period and focused on perioperative critical events and adjunctive procedures as categorical outcome measures collected during the operation. Patients were separated into three groups on the basis of the date of their operation, such that group 1 consisted of our first 25 cases, group 2 our next 25 cases, and group 3 our last 25 cases.

RESULTS

At least one critical event and adjunctive procedure marked 67 (89%) of 75 cases. In 51%, there were at least two critical events and adjunctive procedures. There were no immediate open conversions or intraoperative deaths. Access problems occurred in 28% of the 75 cases and were addressed by use of brachial-femoral artery access (30%), iliac artery/aortic bifurcation balloon angioplasty (8%), and iliofemoral conduits (4%). Graft foreshortening was the most common deployment event (44%), necessitating distal covered extensions. Iliac graft limb twists and kinks occurred in 12% of cases and were managed with balloon angioplasty and uncovered stents. General incidents included balloon ruptures (10%), arterial dissections (6%), iliac artery rupture (2.6%), and lower extremity ischemia (4%). The two cases of iliac artery rupture were managed with distal covered extensions, and there were no cases of atheroemboli. Intraoperative endoleaks were encountered in 44% of the cases and included proximal attachment sites (15%), distal attachment sites (9%), type 2 sources, and "blushes." Management of intraoperative endoleaks included proximal/distal covered extensions and re-ballooning. Our 30-day endoleak rate was 20%. The incidence of critical events did not decrease in the latter one third compared with the first two thirds of cases.

CONCLUSIONS

Critical events occur frequently during endovascular repair of aortic aneurysms. The intraoperative problems range from the common endoleaks, access and deployment issues, and balloon ruptures, to rare but life-threatening complications such as iliac artery rupture. A toolbox of accessories that includes wires, catheters, large balloons, covered proximal and distal extensions, and uncovered stents is essential given the frequency of adjunctive procedures. Successful aortic endografting requires more than mere familiarity with basic endovascular techniques.

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.

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.

Update on the Talent aortic stent-graft: a preliminary report from United States phase I and II trials

PURPOSE

Phase I and phase II trials were conducted to determine the safety and efficacy of the Talent aortic stent-graft (Medtronic World Medical, Sunrise, Fla) in the treatment of infrarenal abdominal aortic aneurysms (AAA). This is a preliminary report of the technical results and 30-day clinical outcome of these trials.

METHODS

Multicenter prospective trials were conducted to test the Talent stent-graft in high-risk and low-risk patient populations with AAA, including phase I feasibility and phase II clinical trials. The low-risk study included concurrent surgical controls.

RESULTS

In the phase I trial, deployment success was achieved in 92% (23/25 patients), and initial technical success was 78% (18/23 implants without endoleak). The 30-day technical success rate was 96%, with six endoleaks that resolved spontaneously (without need for further intervention); and the 30-day mortality rate was 12% (3/25 patients). The phase II high-risk trial demonstrated a deployment success of 94% (119/127 patients) and an initial technical success of 86% (102/119 implants). The 30-day technical success rate was 96%, and the 30-day mortality rate was 1.5% (2/127 patients). The phase II low-risk trial included a first-generation and a second-generation Talent stent-graft. Deployment success rates were 97% and 99%, respectively, and technical success rates at 30 days were 97% and 96%, respectively. The 30-day mortality rate was 2% in the phase II low-risk first-generation device trial, and the adverse-event rate was 20%. Corresponding figures for the second-generation device were 0% and 1.8%, respectively.

CONCLUSION

The Talent stent-graft can be deployed successfully and achieves endovascular exclusion in a large proportion of patients with AAA. Morbidity and mortality rates are acceptable. One-year clinical results and the comparison with concurrent surgical control subjects remain to be evaluated.

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.

Safety of coil embolization of the internal iliac artery in endovascular grafting of abdominal aortic aneurysms

PURPOSE

During endovascular grafting of an abdominal aortic aneurysm (AAA), iliac limb extension to the external iliac artery may be indicated when the common iliac artery is ectatic or aneurysmal. Preliminary or concomitant coil embolization of the internal iliac artery (IIA) is thus necessary to prevent potential reflux and endoleak. We sought to determine the safety of hypogastric flow interruption in this setting.

METHODS

We retrospectively reviewed 156 patients who underwent stent-graft AAA repair at two institutions between February 1, 1998, and January 31, 1999. Coil embolization of one or both IIAs was undertaken when the diameter of the common iliac artery was more than 20 mm to enable limb endograft extension to the external iliac artery. Bilateral procedures were staged.

RESULTS

Thirty-nine (25%) of 156 patients were selected for coil embolization of one (n = 28) or both (n = 11) IIAs. The interventions were performed before (n = 31) or during (n = 8) the stent-graft procedure. Complications included groin hematomas in 3 patients, iliac artery dissection in 1, failure to catheterize the IIA in 2, and transient rise in the serum creatinine level in 3. One patient had erectile dysfunction, and five patients (13%) had buttock claudication after unilateral occlusion. Serious ischemic complications were not observed.

CONCLUSION

Coil embolization of one or both IIAs appears to be safe in the setting of endovascular grafting of AAA. Buttock claudication is a relatively significant problem and may limit applicability of this strategy to patients who are unfit for standard open 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.

The calibration and validation of a phase-modulated near-infrared cerebral oximeter

OBJECTIVE

This study was undertaken to compare the cerebral oxygenation measured by an experimental phase-modulated near-infrared (NIR) spectroscopy system with capillary saturation estimated from jugular venous oxygen saturation.

METHODS

Jugular venous catheters were placed in 30 patients undergoing carotid endarterectomy and 194 measurements of venous oxygen saturation were obtained intra operatively. Simultaneous measurement of optical path length at 754, 785, and 816 nm was performed using a phase-modulated near-infrared spectroscopy system. Optical calibration was performed using both an optical bench and a scattering mold. Hemoglobin saturation was calculated from NIR measurements using equations derived from diffusion theory. Capillary saturation was calculated from the arterial and venous saturations.

RESULTS

Jugular venous saturations ranged from 41 to 92%. When calibrated using the optical bench, the NIR estimates of hemoglobin saturation deviated from estimated capillary values by an average of 2.6% bias and 4.3% deviation. No systematic bias was noted. NIR values derived from mold calibration were less accurate and precise (4.6% bias and 6.9% deviation.) Use of the initial venous sample as an in vivo calibration improved the accuracy of the mold calibration but did not alter the performance of the bench calibration.

CONCLUSIONS

Under the conditions tested, an experimental phase-modulated near-infrared spectroscopy system calibrated using an optical bench agreed with capillary saturation estimated from jugular venous samples. Further work is necessary to demonstrate valid performance of the system under other conditions.

Stationary arterial wave phenomena

The case of a 38-year-old woman who was struck by an automobile is presented. The workup for lower extremity injuries revealed stationary arterial waves. Recognition of this arteriographic finding may avoid unnecessary confusion or exploration.

Case report 723. Popliteal artery aneurysm

An unusually large, noncalcified popliteal artery aneurysm causing cortical erosion was erroneously diagnosed as a soft-tissue sarcoma. The case stresses the importance of excluding a vascular cause of a mass whenever biopsy is considered. We review the clinical and radiological features of popliteal artery aneurysm and describe the appearance of the aneurysm on MR.

Airway compromise after carotid surgery in patients with cervical irradiation

Symptomatic carotid atherosclerotic disease occurring as a result of cervical irradiation often requires surgical intervention. Airway obstruction is an uncommon problem after most carotid surgery and has not been described for patients with cervical irradiation. Airway obstruction developed after two of five carotid endarterectomy procedures in previously irradiated necks requiring emergency tracheostomy or reintubation. Mechanisms of obstruction included endotracheal tube trauma to the fixed irradiated vocal cords and laryngeal edema caused by surgical dissection in an irradiated field. In addition, one patient in our series demonstrated hypercarbia as a result of bilateral carotid body ablation, a process known to impair the ventilatory response to hypoxia. An increased risk of airway obstruction after carotid surgery exists in patients with prior cervical irradiation. Preventive methods include the use of perioperative steroids and either carotid surgery with local anesthesia or bronchoscopic vocal cord visualization and intubation.

Surgery for radiation-induced symptomatic carotid atherosclerosis

Carotid atherosclerosis occurring secondary to cervical irradiation is known to produce stroke. Transient neurologic symptoms have necessitated surgical intervention to prevent stroke despite concern over technical problems, wound healing, operative risks, and uncertain therapeutic outcome. With this report, 26 surgical procedures in 20 patients are now documented in the literature (12 men--60%; eight women--40%). Mean age of these patients (56 years) was 10 years younger than carotid surgery patients with no prior radiation history. No relationship was noted between elevated serum cholesterol and the subsequent development of radiation-induced carotid atherosclerosis. Surgical procedures performed included carotid endarterectomy in 17 cases (65%) and arterial bypass in nine (35%). The combination of radiation therapy and previous neck surgery, including prior radical neck dissection, did not adversely influence operability. Surgical outcome was uniformly good with only one stroke (4%) documented in the perioperative period. Longer follow-up on our six cases (mean two years) disclosed neither new clinical symptoms nor the development of hemodynamically significant restenosis.

Prehepatic total parenteral nutrition in the chair-adapted primate

The relative efficacy of prehepatic and central venous infusion of total parenteral nutrition (TPN) was evaluated in a chair-adapted primate model. Four adult male monkeys (Macaca fascicularis) underwent surgical placement of a silastic catheter in both the portal vein (PV) and superior vena cava (SVC). Following recovery (10 days), each animal received two courses of TPN (100 kcal and 4 g of protein/kg/day) for 10 days each via the PV and SVC in an alternating crossover manner. The prehepatic (PV) infusion of TPN in the well nourished, chair-adapted primate results in maintenance of weight (PV: delta - 0.07 kg; SVC:delta - 0.07 kg), nitrogen equilibrium (PV:+ 0.8 g N/day; SVC: + 0.7 g N/day), and trends in serum albumin (PV:delta - 0.35 g %; SVC: delta - 0.38 g %), and total iron binding capacity (PV:delta + 44 mg %; SVC:delta + 8.67 mg %) comparable to the SVC route. No significant abnormalities in liver enzyme production were observed with either route of infusion. Whole body protein synthesis rates using 15N-glycine tracer were likewise comparable (PV = 2.05 g N/kg/day; SVC = 2.18 g N/kg/day). Prehepatic delivery and primary hepatic modulation of substrates does not substantially improve the efficacy of parenteral nutrient administration. Intestinal modification of substrates may be the most important contributing factor in the supposed superiority of enteral alimentation.

Emergency thoracotomy in the surgical intensive care unit after open cardiac operation

Since January, 1977, 64 patients (3%) out of 2,112 who underwent open cardiac operation had 74 emergency thoracotomies in the surgical intensive care unit 10 minutes to 12 days after operation. In all instances thoracotomy was performed for inadequate circulation. Patients were divided into two groups. In Group 1, 44 patients suddenly and unexpectedly became hypotensive due to an arrhythmia (13 patients), sudden massive bleeding (15), suspected tamponade (6), or unexplained reasons (10). In Group 2 (20 patients), circulatory insufficiency was progressive despite maximum pharmacological and intraaortic balloon support. Circulation was restored after 37 of the 74 thoracotomies (50%), including 8 in Group 2. Nineteen patients (30%) were ultimately discharged; however, no patient in Group 2 survived hospitalization. Of the 19 survivors in Group 1, only 2 of the 13 with a sudden arrhythmia and 3 of the 10 with unexplained hypotension survived. However, 5 of the 6 with tamponade and 9 of the 15 with sudden massive bleeding survived. Overall, 43% of Group 1 patients survived. We conclude that emergency thoracotomy in the surgical intensive care unit after open-heart operation may be lifesaving if performed promptly in patients with sudden, unexpected hypotension. The incidence of wound infection in survivors in 5% whether or not the chest is closed in the operating room.

Inadvertent transplantation of a melanoma

A cadaver renal allograft recipient with normal function for over 3 years developed metastatic melanoma and died within months despite cessation of immunosuppression and allograft nephrectomy. Two additional immunotherapeutic modalities were attempted when it became obvious that the tumor was not a de novo malignancy but rather an inadvertently transplanted one. Neither reexposure to the allograft antigens nor administration of alloantiserum from the patient who had received and rejected the mate of the kidney from the same donor affected the rapid growth of the melanoma in our patient. Of extreme interest is that a focus of melanoma was found in the allograft removed from the surviving patient.