Mitchell H. Goldman

Iliac artery stenting versus surgical reconstruction for TASC (transatlantic inter-society consensus) type B and type C iliac lesions

OBJECTIVE The TransAtlantic Inter-Society Consensus (TASC) document did not define the best treatment for moderately severe iliac artery lesions, ie, TASC type B and type C iliac lesions, because of insufficient solid evidence to make firm recommendations. The purpose of this study was to evaluate the influence of risk factors on outcome of iliac stenting and operative procedures used to treat TASC type B and type C lesions. METHODS Over the 5 years from 1996 to 2001, 188 endovascular and direct aortoiliac surgical reconstruction procedures were performed in 87 women and 101 men with TASC type B and type C iliac lesions and chronic limb ischemia. The criteria prepared by the Ad Hoc Committee on Reporting Standards (Society for Vascular Surgery/International Society for Cardiovascular Surgery (SVS/ISCVS) were followed to define variables. Both univariate analysis (Kaplan-Meier method) and multivariate analysis (Cox proportional hazards model) were used to determine the association between variables, cumulative patency rate, limb salvage, and survival. RESULTS Indications for revascularization were disabling claudication (73%), limb salvage (25%), and blue toe syndrome (2%). Patients in the surgery group (n = 52) had significantly higher primary patency rates compared with patients in the stent group (n = 136) at univariate analysis (Kaplan-Meier method, log-rank test; P =.015). Primary patency rates at 1, 3, and 5 years were 85%, 72%, and 64% after iliac stenting, and 89%, 86%, and 86% after surgical reconstruction, respectively. Univariate and multivariate Cox regression analysis enabled identification of poor runoff (ie, runoff score >5 for unilateral procedures or >2.5 for bilateral outflow procedures; relative risk, 2.5; 95% confidence interval [CI], 1.4-4.2; P =.001) as the only independent predictor of decreased primary patency in all patients. However, stratified analysis including only patients with poor runoff revealed that patients undergoing iliac stenting had significantly lower primary patency rates compared with those undergoing surgical reconstruction (Kaplan-Meier method, log-rank test; P =.05). External iliac artery disease and female gender were also identified as independent predictors of decreased primary stent patency. CONCLUSIONS Poor infrainguinal runoff is the main risk factor for decreased primary patency after surgical reconstruction and iliac stenting to treat TASC type B and type C iliac lesions. However, primary patency is less affected by poor runoff in patients undergoing surgical procedures. The presence of poor runoff, external iliac artery disease, and female gender are independent predictors of poor outcome after iliac stenting, and therefore these risk factors should determine the need for surgical reconstruction.

Endotension Distribution and the Role of Thrombus following Endovascular AAA Exclusion

PURPOSE To determine the pattern of strain and pressure transmitted to an aortic aneurysm wall before and after endovascular exclusion and to evaluate the role of sac thrombus on the conduction of pressure and wall strain. METHODS Three canine thoracic aortas were used to create abdominal aortic aneurysms (AAA). The segments were placed on a pulsatile pump system, and 8 strain transducers were positioned in the aneurysm sac. Baseline strain/pressure (S/P) was recorded in 1 animal, then the AAA was excluded with a stent-graft. Thrombin was injected into the sac, and strain/pressure was recorded at 7 systemic pressures (35 to 120 mmHg) over 6 hours. The thrombus was replaced with fibrin glue, and S/P was recorded over 4 hours. Additional trials using whole and 50% diluted unclotted blood were performed prior to sac thrombosis. Computed tomography and angiography were performed before and after aneurysm exclusion. RESULTS Pressure transmitted to the aneurysm wall decreased following stent-graft placement (p<or=0.001). Strain/pressure was not distributed evenly in the sac (p<or=0.05), and varying systemic pressures did not affect this distribution. Pressures near the stent-graft were higher than those laterally (p<or=0.001) in all trials with interposed fresh thrombus and fibrin thrombus. The fibrin group had elevated baseline measurements, but correction for the elevated values did not influence the statistical significance (p<or=0.001). Blood and fibrin thrombus reduced transmitted wall pressure to a similar degree. Overall S/P in the fluid-filled nonclotted sac was significantly lower (p<or=0.001) than in the thrombus groups. CONCLUSIONS Endovascular AAA exclusion reduced strain and pressure conducted to the aneurysm wall, and the distribution of transmitted pressure in the excluded sac without endoleak differed regardless of the sac contents. Fresh thrombus reduced transmittedS/P in all trials at all systemic pressures, as did fibrin thrombus but in a less predictable fashion.

Iliac artery stenting in patients with poor distal runoff: influence of concomitant infrainguinal arterial reconstruction

OBJECTIVE Inadequate infrainguinal runoff is considered an important risk factor for iliac stent failure. However, the influence of concomitant infrainguinal arterial reconstruction (CIAR) on iliac stent patency is unknown. This study evaluated the influence of CIAR on outcome of iliac angioplasty and stenting (IAS) in patients with poor distal runoff. METHODS Over 5 years (1996 to 2001), 68 IAS procedures (78 stents) were performed in 62 patients with poor distal runoff (angiographic runoff score >or=5). The SVS/AAVS reporting standards were followed to define outcome variables and risk factors. Data were analyzed with both univariate analysis (Kaplan-Meier method [K-M]) and regression analysis (Cox proportional hazards model). RESULTS Indications for iliac artery stenting were disabling claudication (59%) and limb salvage (41%). Of the 68 procedures, IAS with CIAR was performed in 31 patients (46%), and IAS alone was performed in 37 patients (54%). Patients undergoing IAS with CIAR were older (P =.03) and had more extensive and multifocal iliac artery occlusive disease, with more TASC (TransAtlantic Inter-Society Consensus) type C lesions (P =.03), compared with patients undergoing IAS alone. No other significant differences in risk factors were noted. Runoff scores between patients undergoing IAS with CIAR and those undergoing IAS alone were not significantly different (median runoff scores, 6 [range, 5-8] and 7 [range, 5-9], respectively; P =.77). Primary stent patency rate at 1, 3, and 5 years was 87%, 54%, and 42%, respectively, for patients undergoing IAS with CIAR, and was 76%, 66%, and 55%, respectively, for patients undergoing IAS. Univariate analysis revealed that primary stent patency rate was not significantly different between the 2 groups (K-M, log-rank test, P =.81). Primary graft patency rate for CIAR was 81%, 52%, and 46% at 1, 3, and 5 years, respectively. Performing CIAR did not affect primary iliac stent patency (relative risk, 1.1; 95% confidence interval, 0.49-2.47; P =.81). Overall, there was a trend toward improved limb salvage in patients undergoing IAS with CIAR, compared with those undergoing IAS alone (K-M, log rank test, P =.07). CONCLUSION In patients undergoing IAS with poor distal runoff, CIAR does not improve iliac artery stent patency. Infrainguinal bypass procedures should therefore be reserved for patients who do not demonstrate clinical improvement and possibly for those with limb-threatening ischemia.

Effect of anesthetic technique on cardiac morbidity following carotid artery surgery

PURPOSE To investigate the effect of anesthetic technique on cardiac morbidity after carotid artery surgery. PATIENTS AND METHODS From 1991 to 1994, 266 consecutive carotid endarterectomies were performed under local/regional (n=140) or general anesthesia (n=126). The effects of anesthetic technique on postoperative adverse cardiac events were assessed retrospectively. RESULTS Preoperative cardiac testing was performed in all patients undergoing general or local/regional anesthesia. Medical characteristics were similar among patients in both groups. Forty-seven adverse cardiac events (4 myocardial infarction, 9 congestive heart failure, 7 angina, and 27 new ventricular dysrhythmias) occurred postoperatively in 38 patients (14.3%). There were no deaths. The relative risks of general anesthesia for dysrhythmias, myocardial infarction, angina, congestive heart failure, and total adverse cardiac events were 2.22, 0.37, 0.83, 1.38, and 1.5, respectively. The only statistically significant differential was the increased risk of postoperative dysrhythmias after general anesthesia (P<0.03). CONCLUSIONS Major cardiac morbidity following carotid endarterectomy is independent of anesthetic technique.

Healing characteristics of intraarterial stented grafts: Effect of intraluminal position on prosthetic graft healing

BACKGROUND The purpose of this study was to investigate the effect of complete intraluminal placement on prosthetic graft healing. METHODS Thirty dogs underwent infrarenal abdominal aorta polytetrafluoroethylene interposition (12) or intraluminal stented (18) grafting. Grafts were removed at 4 and 8 weeks. Length of endothelial ingrowth and intima to media height ratios (IMHRs) were calculated. Perianastomotic endothelial (CD31+, factor VIII [FVIII+]), smooth muscle (actin+), macrophage (CD44+), and proliferating (PCNA+) cell content was determined. RESULTS In control grafts mean proximal and distal anastomotic endothelial cell ingrowth was 0.42 +/- 0.06 and 0.47 +/- 0.08 cm at 4 weeks and 1.10 +/- 0.24 and 0.94 +/- 0.17 cm at 8 weeks. In intraluminal grafts mean proximal and distal anastomotic endothelial cell ingrowth was 1.57 +/- 0.09 and 1.54 +/- 0.12 cm at 4 weeks and 1.88 +/- 0.06 and 2.11 +/- 0.25 cm at 8 weeks. Endothelial ingrowth was greater in all stented grafts (p < 0.001). Mean proximal anastomosis IMHRs were 1.01 +/- 0.16 for 4-week and 1.42 +/- 0.16 for 8-week control grafts and 0.59 +/- 0.18 for 4-week and 0.50 +/- 0.14 for 8-week stented grafts. Similar IMHR values were present at the distal anastomosis. Lower IMHRs were observed in stented grafts (p < 0.05). Content of CD44+, PCNA+, and FVIII+ cells were reduced both proximally and distally in 4-week stented grafts (p < 0.05). Distal content of CD31+ and actin+ cells was greater in 4-week stented grafts (p < 0.05). At 8 weeks CD44+ cell content decreased in controls (p < 0.05). CONCLUSIONS Intraluminal location enhances prosthetic graft reendothelialization and attenuates intimal thickening.

Distribution of sac pressure in an experimental aneurysm model after endovascular repair: the effect of endoleak types I and II.

PURPOSE To study in an experimental aneurysm model the differential distribution of strain/pressure (S/P) on the aneurysm wall before and after endograft exclusion and in the presence of individual type I and type II endoleaks. METHODS Two tapered elliptical Gore-Tex patches were sutured to an anterior and posterior longitudinal arteriotomy of an 8-mm Gore-Tex tube graft, thus creating a fusiform aneurysm. Two S/P transducers were placed at the proximal sac adjacent to the proximal neck, 2 at the site of the widest sac diameter, and 2 at the sac adjacent to the distal neck. The aneurysm, which was connected to a pulsatile pump system, was excluded using a 10-mm endograft. Type I and type II endoleaks were created and tested individually. S/P measurements were obtained at systemic systolic pressures (BP) of 80, 110, and 150 mmHg. Thrombosis of the sac contents was induced by injection of thrombin and calcium in the sac. Angiography was used to verify presence or absence of flow in the sac. RESULTS Aneurysm exclusion resulted in significant S/P reductions at all 3 BP levels versus prior to exclusion (p<0.05). Thrombus in the sac did not alter S/P in the excluded sac (p>0.05 for all 3 BP levels). In the presence of a proximal type I endoleak, S/P distribution was not uniform, and S/P at the proximal neck was close to S/P prior to exclusion (p>0.05 no graft versus type I endoleak for all 3 BP levels). This was also true in the presence of thrombus. With a type II endoleak, S/P was more evenly distributed and was not significantly elevated compared to the pressure without an endoleak (p>0.05, graft versus type II endoleak for all 3 BP levels). Thrombus had no effect on intrasac S/P with a type II endoleak. Intrasac S/P was significantly higher in the presence of a type I endoleak compared to a type II endoleak when BP=150 mmHg (p=0.008). CONCLUSIONS Endovascular exclusion of an aneurysm results in uniform S/P reduction in the aneurysm sac. Type I endoleak, but not type II endoleak, results in significantly higher S/P in an area of the sac adjacent to the proximal neck. Thrombus does not result in significantly different S/P distribution in the aneurysm sac.

Factors affecting patency of venous allografts in miniature swine

In immunologically defined National Institutes of Health miniswine, a segment of internal jugular vein was anastomosed to the carotid artery as an interposition graft. Patency of swine major histocompatibility complex matched, one haplotype mismatched, and complete mismatched veins was 9.8, 6.3, and 3.0 weeks respectively (p = 0.009). More than 90% of mismatched and 20% of matched allografts developed a positive crossmatch before occlusion (p = 0.006). The mixed lymphocyte response did not predict graft occlusion. Treatment of 10 swine with cyclosporine (10 mg/kg/day) did not significantly improve patency for one haplotype mismatched grafts. In haplotype mismatched veins, cryopreserved grafts occluded more rapidly than noncryopreserved grafts: mean 2.4 versus 6.3 weeks, respectively (p = 0.002). In all cryopreserved vein grafts, alloantibody appeared at or after graft occlusion rather than before occlusion as seen with fresh allografts (p = 0.046). The mean patency of cryopreserved versus fresh autografts was 3.3 and greater than 32 weeks, respectively (p = 0.004). In summary, these results indicate that (1) allograft patency is related to the degree of swine major histocompatibility complex match and development of cytotoxic alloantibodies; (2) moderate-dose cyclosporine does not prolong allograft patency nor suppress development of antibody; (3) cryopreservation may accelerate graft occlusion through nonimmunologic mechanisms.

Regulation of fibrinolysis in aortic surgery

The existence of inhibitors of plasminogen activator has been shown to play an important role in regulation of fibrinolysis and postoperative thrombosis. Platelets and endothelium are sources of plasminogen activator inhibitor (PAI). This study determines the contribution of platelet-released PAI to perioperative fibrinolytic shutdown. PAI levels were measured in 25 patients having aortic surgery. In nine patients the platelet-released PAI contribution was determined by in vitro activation of platelets with phorbol-myristate-acetate (PMA). Mean preoperative PAI levels (3.78 +/- 1.19 U/ml) were similar to controls (3.01 +/- 1.04 U/ml) (p greater than 0.05). Plasma PAI showed an operative increase to a maximum at 8 hours postoperatively and returning to preoperative values by the second postoperative day. In the nine patients who were subjected to studies with in vitro activation, the preoperative PAI level (4.0 +/- 0.9 U/ml) was elevated to 5.1 +/- 0.7 U/ml (p = 0.001) with PMA induction. Maximum stimulated release of platelet granule contents (platelet releasate) could account for an increase of only 1.0 U/ml compared with a postoperative increase of 2.3 U/ml. Postoperative mean peak plasma PAI (6.3 +/- 0.4 U/ml) could not be further elevated by induced release (6.3 +/- 0.4 U/ml) (p = 0.003). A statistically significant increase in PAI occurred in aortic surgery patients postoperatively. The platelet releasable pool of PAI contributed to the increase and was functionally exhausted postoperatively. Postoperative increases of PAI were twice that induced by platelet in vitro stimulation alone. The perioperative increase in PAI was partly due to platelet release.

Vertebrobasilar syndrome associated with subclavian origin of the right internal carotid artery

A case of absence of the right common carotid artery with origin of the external carotid artery from the innominate artery and origin of the internal carotid artery from the right subclavian artery proximal to the right vertebral artery is presented. Atherosclerotic occlusion at the origin of the right subclavian artery and occlusion of the left internal carotid artery resulted in a vertebrobasilar syndrome. Blood flow from the right external carotid reconstituted the right vertebral artery via muscular collateral vessels, moving first retrograde to the subclavian artery and then antegrade through the right internal carotid artery. Symptoms were successfully relieved by transposition of the internal carotid to the external carotid artery. This is the second reported case in the literature and the first to be observed in a clinical setting. The anomaly can easily be explained by embryonic persistence of the right ductus caroticus associated with involution of the right third aortic arch.

Effect of balloon-expandable and self-expanding stent fixation on endoluminal polytetrafluoroethylene graft healing

PURPOSE To investigate the effect of stent design and deployment mechanism on endoluminal graft healing. METHOD Twenty dogs underwent infrarenal abdominal aorta polytetrafluoroethylene (PTFE) interposition (6) or intraluminal stented grafting using either a balloon expandable (BE, n = 8) or self-expanding (SE, n = 6) stent design. Grafts were removed at 8 weeks. Length of endothelial ingrowth and intima to media height ratios (IMHR) were calculated. Perianastomotic smooth muscle (Actin+), macrophage (CD44+), proliferating (PCNA+), and platelet-derived growth factor (PDGF+) cell content were determined. RESULTS Mean endothelial ingrowth was 1.10 +/- 0.15 cm (control), 1.88 +/- 0.13 cm (BESG), and 2.16 +/- 0.18 cm (SESG) proximally; and 0.94 +/- 0.12, 2.11 +/- 0.11 cm, and 2.16 +/- 0.15 cm, respectively, at the distal anastomosis. Endothelial ingrowth was greater in all stented grafts (P <0.001). Mean IMHRs were 1.42 +/- 0.16 (control), 0.50 +/- 0.14 (BESG), and 0.77 +/- 0.2 (SESG) proximally; and 0.84 +/- 0.1, 0.42 +/- 0.09, and 0.77 +/- 0.12 (SESG) distally. Lower IMHRs were observed in all stented graft regions (P <0.05) except the distal anastomosis of SESG. The PDGF+ and PCNA+ cell content was decreased, and Actin+ cell content was increased in all stented grafts (P <0.05). CONCLUSION Intraluminal location enhances endothelialization and attenuates intimal thickening in PTFE grafts. The enhanced healing of intraluminal stented grafts is irrespective of the type of stent or deployment mechanism used.