Michael R. Lepore

CryoPlasty therapy of the superficial femoral and popliteal arteries: A reappraisal after 44 months' experience

OBJECTIVES Long-term patency remains a significant hurdle in the minimally invasive treatment of arteriosclerosis in the superficial femoral (SFA) and popliteal arteries. CryoPlasty therapy (PolarCath, Boston Scientific Corp, Natick, Mass) is a novel approach designed to significantly reduce injury, elastic recoil, neointimal hyperplasia, and constrictive remodeling. The technique combines the dilatation forces of percutaneous transluminal angioplasty (PTA) with cold thermal energy applied to the plaque and vessel wall. We previously reported a technical success rate of 96% and a 12-month freedom from restenosis rate of 82.2%. However, a review of the original cohort supplemented by experience with a further 47 lesions has demonstrated less desirable results. METHODS From December 2003 through July 2007, 92 lesions in 64 consecutive patients were treated and followed up for a median of 16 months with statistically significant follow-up at 24 months. RESULTS The immediate technical success rate was 88%. Nine stents were immediately required after unsuccessful CryoPlasty (9.8%) five of which were as a result of a dissection. No unanticipated adverse events occurred, specifically, no thrombus, acute occlusions, distal embolizations, aneurysms, or groin complications. Vascular calcification was responsible for technical failure in six of the 11 immediately unsuccessful procedures. Freedom from restenosis for successfully treated lesions was 57% and 49% at 12 and 24 months, respectively. CryoPlasty of heavily calcified lesions, vein graft lesions, and in-stent stenosis faired poorly. Excluding these lesions from analysis would have resulted in an immediate success of 94% (81 of 86) and freedom from restenosis of 61% and 52% at 12 and 24 months, respectively. However, on an intention-to-treat basis, freedom from restenosis was 47% and 38% at 12 and 24 months, and CryoPlasty added approximately

CryoPlasty Therapy of the Superficial Femoral and Popliteal Arteries: A Single Center Experience

1700 to the cost of each procedure. CONCLUSION Analysis of this expanded, longer-term data suggests that our earlier, smaller study provided an overly optimistic appraisal of the benefits of CryoPlasty. It is possible that a larger analysis might have identified a subset of patients or lesions that would benefit from CryoPlasty, but considering the additional cost, we no longer use this technique in our practice.

Treatment of Experimentally Induced Caval Thrombosis With Oral Low Molecular Weight Heparin and Delivery Agent in a Porcine Model of Deep Venous Thrombosis

Long-term patency remains a significant hurdle in the minimally invasive treatment of arteriosclerosis in the superficial femoral and popliteal arteries. New technologies designed to address the sources of restenosis have recently been introduced. CryoPlasty therapy (Boston Scientific, Natick, Mass) is a new approach designed to significantly reduce injury, elastic recoil, stent implantation, neointimal hyperplasia, and constrictive remodeling. The technique combines the dilatation forces of percutaneous transluminal angioplasty with cold thermal energy applied to the plaque and vessel wall. The cumulative effect of limiting the sources of restenosis with CryoPlasty therapy was shown to demonstrate longer term patency in a prospective, multicenter, Investigational Device Exemption study of the PolarCath Peripheral Dilatation System. The CryoPlasty therapy experience of 1 center is reported, in which 47 lesions in 32 consecutive patients (34 procedures, 33 limbs) were treated. The technical success rate was 96%. There were no type 3 flow-limiting dissections, and only 4 (8.5%) lesions were stented. There were no unanticipated adverse events, specifically no thrombus, acute occlusions, distal embolizations, aneurysms, or groin complications. With an average follow-up of 12 months, only 5 lesions have recurred, 4 requiring re-intervention. The 12-month freedom from restenosis for lesions and limbs treated was 82.2% and 84.4%, respectively. These results are similar to the findings of the Investigational Device Exemption study and are encouraging. CryoPlasty therapy appears to be a viable endovascular therapeutic option to achieve longer term patency without compromising options for future interventions. The lack of early occlusions may be due to a low rate of spiral dissection that may be a particular benefit of this form of angioplasty.

Contralateral carotid artery occlusion is not a contraindication to carotid endarterectomy even if shunts are not routinely used

OBJECTIVE This experiment evaluated enterally administered low molecular weight heparin (LMWH) combined with sodium N-[10-(2-hydroxybenzoyl)amino] decanoate (SNAD) for the treatment of induced venous thrombosis. SUMMARY BACKGROUND DATA SNAD is a delivery agent that potentiates the gastrointestinal absorption of LMWH. METHODS Forty female pigs were equally assigned to four groups: control (saline); enteral LMWH, 2,000 IU/kg; enteral SNAD, 50 mg/kg; and enteral LMWH, 2,000 IU/kg and SNAD, 50 mg/kg. Under fluoroscopic guidance, the infrarenal vena cava was occluded with a balloon catheter. Two milliliters of ethanol was injected into the distal vena cava. The inflated balloon catheter remained in situ for 5 days, at which time animals angiographically exhibiting thrombus were randomly assigned to the four groups. Study medications were dosed at 12-hour intervals by means of a gastrostomy tube placed previously. After 7 days of treatment, thrombus was extracted. A separate group of 10 animals was used to measure plasma antifactor Xa levels for 6 hours after enteral dosing of LMWH/SNAD. RESULTS The amount of residual thrombus after treatment with enteral LMWH/SNAD was significantly decreased. Antifactor Xa levels were significantly elevated in the LMWH/SNAD group versus baseline. CONCLUSION The combination of enterally administered LMWH and SNAD given for 7 days appeared to decrease caval thrombosis in this model of deep vein thrombosis. Enteral LMWH/SNAD effected an increase in plasma levels of antifactor Xa.

Long-term safety of left renal vein division and ligation to expedite complex abdominal aortic surgery

OBJECTIVE Although controversial, carotid artery stenting (CAS) has been proposed as being safer than carotid endarterectomy (CEA) for patients with a contralateral internal carotid occlusion (CCO). Arguably, with a CCO, CAS should be even safer than CEA if a shunt is not used. Accordingly, we reviewed our experience with 2183 CEAs performed routinely without a shunt to evaluate the risk of CEA performed in a subset of 147 patients with a CCO. METHODS Between 1988 and 2011, 147 CEAs (111 men [75%], 36 women [25%]) were routinely performed without a shunt despite CCO. Of these patients, 76% were asymptomatic. CEAs were performed by seven surgeons using standard techniques (not eversion), with patients under general anesthesia and blood pressure maintained at >130 mm Hg. All patients received heparin (7500 U), and protamine reversal was routine. Median cross-clamp time was 20 minutes (range, 14-40 minutes). RESULTS Three neurologic events occurred ≤ 30 days (2.0%). One transient ischemic attack (TIA) occurred immediately, and one occurred on the first postoperative day due to occlusion of the endarterectomy site. One patient sustained an immediate stroke and died of a large computed tomography-documented atheroembolic shower. CONCLUSIONS Our data demonstrate the safety of CEA in the presence of a CCO, even when performed without a shunt. It is unlikely that the stroke or delayed TIA could be attributed to nonshunting or CCO. Even if so, the stroke and death rates would be lower than those previously reported for patients undergoing CEA in the presence of a CCO. This may be due to short cross-clamp times, careful technique, general anesthesia, and blood pressure support. Given these low adverse event rates, our experience refutes the assumption that patients with a CCO are at such a high risk for CEA that the only alternative is CAS.

Influence of NASCET/ACAS trial eligibility on outcome after carotid endarterectomy

BACKGROUND Left renal vein division and ligation (LRVDAL) is performed to facilitate complex abdominal aortic surgery. Surgeons restore continuity of the vein due to concern that ligation could cause renal compromise or hematuria. However, we report the short and long-term safety of left renal vein division and ligation. METHOD Between 1992 and 2007, we divided the left renal vein in 56 patients (40 males, 16 females) ages 57 to 84 (average 74-years-old) who were treated for aortic occlusive disease (9) or abdominal aortic aneurysm (47). Patients requiring concomitant renal artery reconstruction were excluded from this review. Suprarenal cross-clamp was used in 51 patients with temporary vessel-loop control of the renal arteries. Creatinine (Cr) and glomerular filtration rates (eGFR) were measured pre-, post-, and long-term after surgery. Outpatient records of all patients that had survived more than 12 months were also reviewed in order to evaluate the late effects on renal function or symptoms possibly related to LRVDAL. RESULTS Median procedure duration was 157 (61-375) minutes. Median cross-clamp time was 16 (10-45) minutes. Median intensive care unit (ICU) and hospital length of stays were 2 (1-11) days and 7 (4-58) days, respectively. There were no deaths. There were no complications directly related to renal vein ligation. Hematuria, seen in 2 patients, was a result of traumatic insertion of a Foley catheter. Median pre-op and discharge Cr levels were 1.1 mg/dL (0.7-2.4 mg/dL) and 1.1 mg/dL (0.6-2.1 mg/dL), respectively (P < .5). Median change in Cr was 0.0 mg/dL and only increased in 14 patients (maximum increase 0.9 mg/dL). Median pre-op and discharge eGFR was 61 mL/minute (28-137 mL/minute/1.73 m2) and 67 mL/minute (32-138 mL/minute/1.73 m2), respectively (P < .5). Cr and eGFR in the 2 patients with a Cr of >2.0 mg/dL remained unchanged post-op. Only 2 patients with a Cr of <2.0 mg/dL had a post-op Cr >2.0 mg/dL and both returned to normal by day 3 post-op. Thirty-six patients have been followed for more than a year (median 34.5 months, maximum 144 months) and Cr has remained stable in all but 2 patients. These 2 patients, both with a pre-op Cr of 1.5 mg/dL, subsequently developed Cr levels of 2.1 mg/dL and 2.4 mg/dL but maintained baseline Cr levels for 25 and 34 months, respectively, before demonstrating these elevated levels which have proven to be unrelated to renal vein ligation. Hematuria and flank pain have never been recorded after discharge. CONCLUSION Restoration of left renal vein continuity after LRVDAL may be unnecessary since renal compromise and hematuria was not encountered in this long-term analysis.