Prosthetic bypass for restenosis after endarterectomy or stenting of the carotid artery

OBJECTIVE: The objective of this study was to evaluate the results of prosthetic carotid bypass (PCB) with polytetrafluoroethylene (PTFE) grafts as an alternative to carotid endarterectomy (CEA) in treatment of restenosis after CEA or carotid artery stenting (CAS). METHODS: From January 2000 to December 2014, 66 patients (57 men and 9 women; mean age, 71 years) presenting with recurrent carotid artery stenosis ≥70% (North American Symptomatic Carotid Endarterectomy Trial [NASCET] criteria) were enrolled in a prospective study in three centers. The study was approved by an Institutional Review Board. Informed consent was obtained from all patients. During the same period, a total of 4321 CEAs were completed in the three centers. In these 66 patients, the primary treatment of the initial carotid artery stenosis was CEA in 57 patients (86%) and CAS in nine patients (14%). The median delay between primary and redo revascularization was 32 months. Carotid restenosis was symptomatic in 38 patients (58%) with transient ischemic attack (n = 20) or stroke (n = 18). In this series, all patients received statins; 28 patients (42%) received dual antiplatelet therapy, and 38 patients (58%) received single antiplatelet therapy. All PCBs were performed under general anesthesia. No shunt was used in this series. Nasal intubation to improve distal control of the internal carotid artery was performed in 33 patients (50%), including those with intrastent restenosis. A PTFE graft of 6 or 7 mm in diameter was used in 6 and 60 patients, respectively. Distal anastomosis was end to end in 22 patients and end to side with a clip distal to the atherosclerotic lesions in 44 patients. Completion angiography was performed in all cases. The patients were discharged under statin and antiplatelet treatment. After discharge, all of the patients underwent clinical and Doppler ultrasound follow-up every 6 months. Median length of follow-up was 5 years. RESULTS:No patient died, sustained a stroke, or presented with a cervical hematoma during the postoperative period. One transient facial nerve palsy and two transient recurrent nerve palsies occurred. Two late strokes in relation to two PCB occlusions occurred at 2 years and 4 years; no other graft stenosis or infection was observed. At 5 years, overall actuarial survival was 81% ± 7%, and the actuarial stroke-free rate was 93% ± 2%. There were no fatal strokes. CONCLUSIONS: PCB with PTFE grafts is a safe and durable alternative to CEA in patients with carotid restenosis after CEA or CAS in situations in which CEA is deemed either hazardous or inadvisable

Non Linear Current Response of a Many-Level Tunneling System: Higher Harmonics Generation

The fully nonlinear response of a many-level tunneling system to a strong alternating field of high frequency $\omega$ is studied in terms of the Schwinger-Keldysh nonequilibrium Green functions. The nonlinear time dependent tunneling current $I(t)$ is calculated exactly and its resonance structure is elucidated. In particular, it is shown that under certain reasonable conditions on the physical parameters, the Fourier component $I_{n}$ is sharply peaked at $n=\frac {\Delta E} {\hbar \omega}$, where $\Delta E$ is the spacing between two levels. This frequency multiplication results from the highly nonlinear process of $n$ photon absorption (or emission) by the tunneling system. It is also conjectured that this effect (which so far is studied mainly in the context of nonlinear optics) might be experimentally feasible.Comment: 28 pages, LaTex, 7 figures are available upon request from [email protected], submitted to Phys.Rev.

Long-term results of a multicenter randomized study on direct versus crossover bypass for unilateral iliac artery occlusive disease.

To compare late patency after direct and crossover bypass in good-risk patients with unilateral iliac occlusive disease not amenable to angioplasty. Between May 1986 and March 1991, 143 patients with unilateral iliac artery occlusive disease and disabling claudication were randomized into two surgical treatment groups, ie, crossover bypass (n = 74) or direct bypass (n = 69). The size of the patient population was calculated to allow detection of a possible 20% difference in patency in favor of direct bypass with a one-sided alpha risk of 0.05 and a beta risk of 0.10. Patients underwent yearly follow-up examinations using color flow duplex scanning with ankle-brachial systolic pressure index measurement. Digital angiography was performed if hemodynamic abnormalities were noted. Median follow-up was 7.4 years. Primary endpoints were primary patency and assisted primary patency estimated by the Kaplan-Meier method with 95% confidence interval. Secondary endpoints were secondary patency and postoperative mortality and morbidity. Cardiovascular risk factors, preoperative symptoms, iliac lesions TASC class (C in 87 [61%] patients and D in 56 [39%] patients), and superficial femoral artery (SFA) run-off were comparable in the two treatment groups. One patient in the direct bypass group died postoperatively. Primary patency at 5 years was higher in the direct bypass group than in the crossover bypass group (92.7 +/- 6.1% vs 73.2 +/- 10%, P = .001). Assisted primary patency and secondary patency at 5 years were also higher after direct bypass than crossover bypass (92.7 +/- 6.1% vs 84.3 +/- 8.5%, P = .04 and 97.0 +/- 3.0% vs 89.8 +/- 7.1%, P = .03, respectively). Patency at 5 years after crossover bypass was significantly higher in patients presenting no or low-grade SFA stenosis than in patients presenting high-grade (> or =50%) stenosis or occlusion of the SFA (74.0 +/- 12% vs 62.5 +/- 19%, P = .04). In both treatment groups, patency was comparable using polytetrafluoroethylene (PTFE) and polyester grafts. Overall survival was 59.5 +/- 12% at 10 years. This study showed that late patency was higher after direct bypass than crossover bypass in good-risk patients with unilateral iliac occlusive disease not amenable to angioplasty. Crossover bypass should be reserved for high-risk patients with unilateral iliac occlusion not amenable to percutaneous recanalization

Laparoscopic aortic surgery: Techniques and results.

OBJECTIVE: This review describes and evaluates the results of laparoscopic aortic surgery. METHODS: We describe the different laparoscopic techniques used to treat aortic disease, including (1) total laparoscopic aortic surgery (TLS), (2) laparoscopy-assisted procedures including hand-assisted laparoscopic surgery (HALS), and (3) robot-assisted laparoscopic surgery, with their current indications. Results of these techniques are analyzed in a systematic review of the clinical series published between 1998 and 2008, each containing >10 patients with complete information concerning operative time, clamping time, conversion rate, length of hospital stay, morbidity, and mortality. RESULTS: We selected and reviewed 29 studies that included 1073 patients. Heterogeneity of the studies and selection of the patients made comparison with current open or endovascular surgery difficult. Median operative time varied widely in TLS, from 240 to 391 minutes. HALS had the shortest operating time. Median clamping time varied from 60 to 146 minutes in TLS and was shorter in HALS. Median hospital stay varied from 4 to 10 days regardless of the laparoscopic technique. The postoperative mortality rate was 2.1% (95% confidence interval, 1.4-3.0), with no significant difference between patients treated for occlusive disease or for aneurysmal disease. Conversion to open surgery was necessary in 8.1% of patients and was slightly higher with TLS than with laparoscopy-assisted techniques (P = .07). CONCLUSIONS: Analysis of these series shows that laparoscopic aortic surgery can be performed safely provided that patient selection is adjusted to the surgeon's experience and conversion is liberally performed. The future of this technique in comparison with endovascular surgery is still unknown, and it is now time for multicenter randomized trials to demonstrate the potential benefit of this type of surgery

Localized Argyria Caused by Metallic Silver Aortic Grafts: A Unique Adverse Effect

IntroductionSilver-coated grafts are designed to prevent vascular graft infections. Silver is a safe element but toxic effects have been reported. We describe two cases of possible localized argyria after silver graft implantation.ReportTwo patients presented with perigraft groin collections after implantation of silver grafts. During reoperation, an ashen-grey necrotic substance was seen surrounding the grafts. The grafts were explanted and lower limb perfusion restored. Cultures were negative and both patients had uneventful recoveries.DiscussionOur cases are highly suggestive of a possible unique adverse effect: a combination of localized silver toxicity and neutrophilic mediated tissue destruction