Steven Okuhn

Recurrent carotid stenosis: A consequence of local or systemic factors? The influence of unrepaired technical defects

To determine the influence of unrepaired technical defects as well as systemic risk factors for atherogenesis on carotid artery healing after endarterectomy, we conducted a prospective study using intraoperative duplex scanning with spectral analysis to establish the initial status of the artery (N = 131 arteries), and then we studied these vessels at regular postoperative intervals with the same technique (N = 108 arteries, 265 studies). The vessels were divided into the operated and nonoperated segments of the common, internal, and external carotid arteries, and both intraoperative image and flow data were tabulated by artery segment. The technical factors that were analyzed included defect size, defect type, adjacent segment defects, number of defects, shunt use, vessel reopening, and peak, mean, and end-diastolic frequency and velocity. The systemic risk factors studied were sex, hypertension, diabetes, smoking, randomly drawn total serum cholesterol and triglyceride levels, and perioperative aspirin and dextran use. Data were analyzed by linear logistic regression analysis. Among the technical factors, only intraoperative defect size was significantly associated with risk of recurrent stenosis (p = 0.0175). Although any defect size adversely affected the condition of the vessel during follow-up, the magnitude of this effect was small for smaller defects (size category 1: less than or equal to 40% stenosis or flap length less than or equal to 25% of vessel diameter). The systemic factors that were associated with risk of recurrent stenosis were hypertension (p = 0.0002), smoking (p = 0.0016), and randomly drawn total serum cholesterol level (p = 0.0116). The fact that the operated segments consistently fared worse during follow-up than did the nonoperated segments (p = 0.0044) undoubtedly reflects the inevitable trauma of the endarterectomy, but also emphasizes the important contribution of systemic risk factors in recurrent carotid stenosis. Risk factor modification may be the most effective method of ensuring the durability of carotid endarterectomy.

Does compliance mismatch alone cause neointimal hyperplasia

To define the relationship between compliance mismatch and the development of neointimal hyperplasia, one 3 cm segment of common iliac artery was externally banded in seven dogs, thereby fixing the arterial diameter at end diastole. To quantify compliance, end-diastole diameter and its change with pulse pressure were measured by induction angiometry. This technique uses intravascular soft trifilar wire probes introduced through distally placed polytetrafluoroethylene sidearms. Compliance was checked in the banded and contralateral undissected unbanded control iliac arteries at 3 and 6 months, at which times the vessels were fixed by perfusion, excised, and examined histologically. Sustained (6-month) compliance mismatch was successfully induced within the banded segments (p less than 0.0001), and no compliance mismatch was seen in the control segments (p = 0.357). The intima of all banded vessels was virtually indistinguishable from that in controls grossly and histologically. Mild focal intimal thickening, less than 3 cell layers thick involving less than 5% of the vessel circumference, was typically seen in both banded and control vessels (range 6.57 +/- 6.80 micron to 38.86 +/- 57.16 micron). In marked contrast, at the sites of the polytetrafluoroethylene-to-femoral artery anastomosis, near-occlusive neointimal hyperplasia (1714 +/- 415.47 micron) was seen in all animals. Residual lumen area in the banded and control vessels was only minimally abnormal (range 98.65% +/- 2.18% to 99.96% +/- 0.08%). These data indicate that compliance mismatch alone is an insufficient stimulus for the development of neointimal hyperplasia in the canine model.

Ten-year results of endovascular abdominal aortic aneurysm repair from a large multicenter registry

OBJECTIVE To assess outcomes after endovascular abdominal aortic aneurysm repair (EVAR) in an integrated health care system. METHODS Between 2000 and 2010, 1736 patients underwent EVAR at 17 centers. Demographic data, comorbidities, and outcomes of interest were collected. EVAR in patients presenting with ruptured or symptomatic aneurysms was categorized as urgent; otherwise, it was considered elective. Primary outcomes were mortality and aneurysm-related mortality (ARM). Secondary outcomes were change in aneurysm sac size, endoleak status, major adverse events, and reintervention. RESULTS Overall, the median age was 76 years (interquartile range, 70-81 years), 86% were male, and 82% were Caucasian. Most cases (93.8%) were elective, but urgent use of EVAR increased from 4% in the first 5 years to 7.3% in the last 5 years of the study period. Mean aneurysm size was 5.8 cm. Patients were followed for an average of 3 years (range, 1-11 years); 8% were lost to follow-up. Intraoperatively, 4.5% of patients required adjunctive maneuvers for endoleak, fixation, or flow-limiting issues. The 30-day mortality rate was 1.2%, and the perioperative morbidity rate was 6.6%. Intraoperative type I and II endoleaks were uncommon (2.3% and 9.3%, respectively). Life-table analysis at 5 years demonstrated excellent overall survival (66%) and freedom from ARM (97%). Postoperative endoleak was seen in 30% of patients and was associated with an increase in sac size over time. Finally, the total reintervention rate was 15%, including 91 instances (5%) of revisional EVAR. The overall major adverse event rate was 7.9% and decreased significantly from 12.3% in the first 5 years to 5.6% in the second 5 years of the study period (P < .001). Overall ARM was worse in patients with postoperative endoleak (4.1% vs 1.8%; P < .01) or in those who underwent reintervention (7.6% vs 1.6%; P < .001). CONCLUSIONS Results from a contemporary EVAR registry in an integrated health care system demonstrate favorable perioperative outcomes and excellent clinical efficacy. However, postoperative endoleak and the need for reintervention continue to be challenging problems for patients after EVAR.

Intraoperative assessment of renal and visceral artery reconstruction: The role of duplex scanning and spectral analysis

To refine our ability to assess intraoperatively renal and visceral reconstructions, we have investigated the usefulness of combined duplex scanning and Doppler spectral analysis to determine the technical adequacy and flow characteristics of these repairs. We studied 62 patients (116 arteries) who underwent renal (83 arteries) or visceral (13) reconstruction by transaortic endarterectomy (76), autogenous graft (12) or prosthetic (5) bypass, reimplantation (2), and dilation (1). Twenty-six nonreconstructed vessels were also studied, including preoperative arteries (6), unrepaired arteries (14), and normal renal arteries (donor nephrectomies) (6). Duplex scanning was performed by means of a 7.5 or 10 MHz probe placed in a sterile glove and plastic sleeve. Peak (Vs) and mean (Vm) velocities measured in meters per second were subsequently calculated from frequency spectral analysis. Spectral broadening (SB) and aortic inflow data were also collected and analyzed. There were no complications related to ultrasound scanning. Mean scan time was 7.8 minutes. Fourteen of 26 nonreconstructed vessels (54%) appeared normal by duplex scanning, including all six control (normal) renal arteries. Sixty-five reconstructed arteries (68%) appeared normal, 27 had various minor defects, and four had major defects (three occlusions and one floating thrombus). The major defects were repaired, whereas minor ones were not. Confirmatory studies were obtained in 19 (73%) nonoperated and 73 (76%) operated vessels. There were two false negative duplex studies (sensitivity 89%) and 17 false positive duplex studies--all minor defects (specificity 77%). The predictive value of duplex scans in detecting the presence of confirmed defects was Tau = 0.47 (p = 0.01). Although SB correlated with B-mode imaging alone (Tau = 0.21, p = 0.07), it added no independent value in predicting the results of a confirmatory study. No other variable (Vs, Vm, or aortic inflow) added to the duplex scan in predicting an abnormal confirmatory study. Detailed renal and visceral artery spectral analysis data are provided for validation of this technique and comparison with transcutaneous studies. These data suggest that the requirement for reliable and immediate assessment of renal and visceral reconstructions, particularly those involving transaortic extraction endarterectomy, is satisfied by duplex scanning.

Type II endoleak with or without intervention after endovascular aortic aneurysm repair does not change aneurysm-related outcomes despite sac growth

OBJECTIVE There is considerable controversy about the significance and appropriate treatment of type II endoleaks (T2Ls) after endovascular aneurysm repair (EVAR). We report our long-term experience with T2L management in a large multicenter registry. METHODS Between 2000 and 2010, 1736 patients underwent EVAR, and we recorded the incidence of T2L. Primary outcomes were mortality and aneurysm-related mortality (ARM). Secondary outcomes were change in aneurysm sac size, major adverse events, and reintervention. RESULTS During the follow-up (median of 32.2 months; interquartile range, 14.2-52.8 months), T2L was identified in 474 patients (27.3%). There were no late abdominal aortic aneurysm ruptures attributable to a T2L. Overall mortality (P = .47) and ARM (P = .26) did not differ between patients with and without T2L. Sac growth (median, 5 mm; interquartile range, 2-10 mm) was seen in 213 (44.9%) of the patients with T2L. Of these patients with a T2L and sac growth, 36 (16.9%) had an additional type of endoleak. Of all patients with T2L, 111 (23.4%) received reinterventions, including 39 patients who underwent multiple procedures; 74% of the reinterventions were performed in patients with sac growth. Reinterventions included lumbar embolization in 66 patients (59.5%), placement of additional stents in 48 (43.2%), open surgical revision in 14 (12.6%), and direct sac injection in 22 (19.8%). The reintervention was successful in 35 patients (31.5%). After patients with other types of endoleak were excluded, no difference in overall all-cause mortality (P = .57) or ARM (P = .09) was observed between patients with T2L-associated sac growth who underwent reintervention and those in whom T2L was left untreated. CONCLUSIONS In our multicenter EVAR registry, overall all-cause mortality and ARM were unaffected by the presence of a T2L. Moreover, patients who were simply observed for T2L-associated sac growth had aneurysm-related outcomes similar to those in patients who underwent reintervention. Our future work will investigate the most cost-effective ways to select patients for intervention besides sac growth alone.

Adherence to endovascular aortic aneurysm repair device instructions for use guidelines has no impact on outcomes.

OBJECTIVE Prior reports have suggested unfavorable outcomes after endovascular aortic aneurysm repair (EVAR) performed outside of the recommended instructions for use (IFU) guidelines. We report our long-term EVAR experience in a large multicenter registry with regard to adherence to IFU guidelines. METHODS Between 2000 and 2010, 489 of 1736 patients who underwent EVAR had preoperative anatomic measurements obtained from the M2S, Inc, imaging database (West Lebanon, NH). We examined outcomes in these patients with regard to whether they had met the device-specific IFU criteria. Primary outcomes were all-cause mortality and aneurysm-related mortality. Secondary outcomes were endoleak status, adverse events, reintervention, and aneurysm sac size change. RESULTS The median follow-up for the 489 patients was 3.1 years (interquartile range, 1.6-5.0 years); 58.1% (n = 284) had EVAR performed within IFU guidelines (IFU-adherent group), and 41.9% (n = 205) had EVAR performed outside of IFU guidelines (IFU-nonadherent group). Preoperative anatomic data showed that 62.4% of the IFU-nonadherent group had short neck length, 10.2% had greater angulation than recommended, 7.3% did not meet neck diameter criteria, and 20% had multiple anatomic issues. A small portion (n = 49; 10%) of the 489 patients were lost to follow-up because of leaving membership enrollment (n = 28), moving outside the region (n = 10), or discontinuing image surveillance (n = 11). There was no significant difference in any of the primary or secondary outcomes between the IFU-adherent and IFU-nonadherent groups. Aneurysm sac size change at any time point during follow-up also did not differ significantly between the two groups. A Cox proportional hazard model showed that IFU nonadherence was not predictive of all-cause mortality (hazard ratio, 1.0; P = .91). Similarly, IFU nonadherence was not identified as a risk factor for aneurysm-related mortality or adverse events in stepwise Cox proportional hazards models. CONCLUSIONS In our cohort of EVAR patients with detailed preoperative anatomic information and long-term follow-up, overall mortality and aneurysm-related mortality were unaffected by IFU adherence. In addition, rates of endoleak and reintervention after initial EVAR were similar, suggesting that lack of IFU-based anatomic suitability was not a driver of outcomes.

Intraoperative Use of Ultrasound in Arterial Surgery

Technical perfection is the goal of any arterial reconstruction so as to avoid postoperative complications. Experimental and clinical studies have clearly shown that these operations are imperfect and that some form of intraoperative surveillance is required to decrease the incidence of correctable technical defects. Ultrasound technology is uniquely suited for this role. This article describes the distinct advantages of duplex ultrasound for the intraoperative monitoring of vascular reconstructions.

Long-Term Results of Surgical Therapy for Amaurosis Fugax

The relationship between amaurosis fugax and ipsilateral extracranial cerebrovascular disease and subsequent stroke was not adequately appreciated until 1952 when Fisher (1) described seven patients with monocular loss of vision and contralateral hemiplegia. It has become clear that amaurosis fugax can be a marker for surgically correctable extracranial arterial lesions, and these lesions are repaired with the view toward prevention of retinal or cerebral stroke. Many surgical series that evaluate cerebrovascular reconstruction have been reported (2–9). These studies have indicated that perioperative and long-term results vary with the preoperative indication for surgery. Patients who are operated on for amaurosis fugax and retinal stroke have a longer stroke-free survival than patients operated on for other TIAs or cerebral stroke (9,10). What has not been shown, however, is to what extent cerebrovascular reconstruction prevents subsequent ipsilateral amaurosis fugax, ipsilateral retinal stroke, or ipsilateral cerebral stroke.

VESS05. Long-Term Freedom From Aneurysm-Related Mortality Remains Favorable After Endovascular Abdominal Aortic Aneurysm Repair in a 15-year Multicenter Registry

differences across the specialties. A total of 43% (157 of 368) of total cases involved death of the patient. Among the four specialties, there was a significant (P 1⁄4 .0004) difference in the primary allegation (informed consent, preprocedure negligence, intraprocedural complications, or postprocedural complications) underlying the litigation (Fig). For CTS and VS, there was a predominance of informed consent and preprocedure negligence allegations (70% [7 of 10] and 52% [28 of 54] respectively). Intraprocedural negligence was the most common allegation for IR (59% [23 of 39]), while allegations were more evenly distributed among IC. Conclusions: Key issues were identified regardingmalpractice litigation involving the specialties that commonly perform endovascular procedures. Despite the increasing number of ICs doing peripheral interventions, a largemajority of IC cases were related to coronary treatments. A surprisingly large percentage of VS cases were related to seemingly minor cases. There were significant interspecialty differences in the primary underlying allegations. As the scope of endovascular procedures broadens and deepens, it is important for clinicians to be aware of the legal considerations relevant to their practice.