Amy B. Reed

Society for Vascular Surgery practice guidelines for atherosclerotic occlusive disease of the lower extremities: Management of asymptomatic disease and claudication

Peripheral arterial disease (PAD) continues to grow in global prevalence and consumes an increasing amount of resources in the United States health care system. Overall rates of intervention for PAD have been rising steadily in recent years. Changing demographics, evolution of technologies, and an expanding database of outcomes studies are primary forces influencing clinical decision making in PAD. The management of PAD is multidisciplinary, involving primary care physicians and vascular specialists with varying expertise in diagnostic and treatment modalities. PAD represents a broad spectrum of disease from asymptomatic through severe limb ischemia. The Society for Vascular Surgery Lower Extremity Practice Guidelines committee reviewed the evidence supporting clinical care in the treatment of asymptomatic PAD and intermittent claudication (IC). The committee made specific practice recommendations using the GRADE (Grades of Recommendation Assessment, Development and Evaluation) system. There are limited Level I data available for many of the critical questions in the field, demonstrating the urgent need for comparative effectiveness research in PAD. Emphasis is placed on risk factor modification, medical therapies, and broader use of exercise programs to improve cardiovascular health and functional performance. Screening for PAD appears of unproven benefit at present. Revascularization for IC is an appropriate therapy for selected patients with disabling symptoms, after a careful risk-benefit analysis. Treatment should be individualized based on comorbid conditions, degree of functional impairment, and anatomic factors. Invasive treatments for IC should provide predictable functional improvements with reasonable durability. A minimum threshold of a >50% likelihood of sustained efficacy for at least 2 years is suggested as a benchmark. Anatomic patency (freedom from restenosis) is considered a prerequisite for sustained efficacy of revascularization in IC. Endovascular approaches are favored for most candidates with aortoiliac disease and for selected patients with femoropopliteal disease in whom anatomic durability is expected to meet this minimum threshold. Conversely, caution is warranted in the use of interventions for IC in anatomic settings where durability is limited (extensive calcification, small-caliber arteries, diffuse infrainguinal disease, poor runoff). Surgical bypass may be a preferred strategy in good-risk patients with these disease patterns or in those with prior endovascular failures. Common femoral artery disease should be treated surgically, and saphenous vein is the preferred conduit for infrainguinal bypass grafting. Patients who undergo invasive treatments for IC should be monitored regularly in a surveillance program to record subjective improvements, assess risk factors, optimize compliance with cardioprotective medications, and monitor hemodynamic and patency status.

Preoperative risk factors for carotid endarterectomy: defining the patient at high risk ☆

PURPOSE The efficacy of carotid endarterectomy (CEA) for prevention of stroke has been demonstrated in randomized trials; however, the optimal approach in patients excluded from these trials or who have other significant comorbid conditions remains controversial, particularly with the advent of percutaneous interventions. We examined the influence of putative risk factors on outcome of CEA in a single-center experience. METHODS A retrospective analysis of 1370 consecutive CEA performed from 1990 to 1999 was undertaken. Preoperative risk factors examined included age older than 80 years, congestive heart failure, chronic obstructive pulmonary disease, renal failure (serum creatinine concentration > 2.0 mg/dL), contralateral carotid artery occlusion, recurrent ipsilateral carotid artery stenosis, ipsilateral hemispheric symptoms within 6 weeks, and recent coronary bypass grafting (CABG). The Fisher exact test was used to identify baseline variables associated with perioperative (30 days) risk for stroke or death. Multivariate analysis with Poisson regression was used to study the effect of all univariate criteria in combination. RESULTS In the overall cohort, there were 32 adverse events (2.3%), including 11 deaths (0.8%), 6 disabling strokes (0.4%), and 10 nondisabling strokes (0.7%). There was no significant difference in incidence of perioperative stroke or death between patients with one or more risk factors (n = 689) and those with no risk factors (low risk, n = 681). Thirty-day mortality was significantly greater in patients with two or more risk factors compared with patients with no risk factors (2.8% vs 0.3%; P =.04), but no significant difference was noted in perioperative stroke rate (2.3% vs 1.0%). Univariate analysis demonstrated that contralateral carotid occlusion (n = 75) was the only significant predictor of adverse outcome (5 events, 6.7%) among the variables tested; this was confirmed with multivariate analysis (relative risk, 4.3; 95% confidence interval, 1.2-12.3; P =.01). Five-year survival for patients with two or more risk factors was notably diminished compared with that for patients with no risk factors (38.7% +/- 5.9% vs 75.0% +/- 2.6%; P <.001). Contralateral occlusion was also associated with reduced 5-year survival (38 +/- 11% vs 67 +/- 2%; P <.004). CONCLUSION CEA can be safely performed in patients deemed at high risk, including those aged 80 years or older and others with significant comorbid conditions, with combined stroke and mortality rates comparable to those found in randomized trials, ie, the Asymptomatic Carotid Atherosclerosis Study and the North American Symptomatic Carotid Endarterectomy Trial. Contralateral occlusion may be a predictor for moderately increased perioperative risk and for reduced long-term survival. Caution may be warranted in asymptomatic patients with multiple risk factors, in whom presumed long-term benefit of CEA may be compromised by markedly reduced 5-year survival.

The impact of patient age and aortic size on the results of aortobifemoral bypass grafting

OBJECTIVES On the basis of the widespread belief that aortobifemoral bypass (ABF) represents the optimal mode of revascularization for patients with diffuse aortoiliac disease, vascular surgeons are often aggressive about its application in young adults. We undertook this retrospective evaluation of ABFs performed from 1980 to 1999 to determine whether the results justify this approach. Patients of less than 50 years of age (n = 45) were compared with those aged 50 to 59 years (n = 93) and those aged more than 60 years (n = 146). RESULTS Younger patients were more likely to undergo operation for claudication than were older patients (72% versus 59% and 55%; P <.04). Younger patients were significantly more likely to be smokers (87%) but less likely to have diabetes, hypertension, or cerebrovascular disease. Bypasses were constructed in an end-to-end fashion in 71.1% of patients of less than 50 years versus 68.8% and 71.2% of older patients (P = not significant). The mean diameter of aortic grafts was significantly smaller in younger patients (14.6 mm) than in older patients (15.6 mm and 15.5 mm; P <.01). The need for a subsequent infrainguinal reconstruction was highest in the youngest patients (24% versus 17% and 7%; P <.01). Surgical mortality rates were low in all groups (0%, 1%, and 2.0% for increasing age groups; P = not significant). Five-year primary and secondary patency rates increased significantly with each increase in age interval: 5-year primary patency rate: less than 50 years, 66% +/- 8%; 50 to 59 years, 87% +/- 5%; more than 60 years, 96% +/-2% (P <.05 for all comparisons). Five-year secondary patency rates were: less than 50 years, 79% +/- 7%; 50 to 59 years, 91% +/- 4%; more than 60 years, 98% +/- 2% (P <.05 for all comparisons). Five-year survival rate was comparable in all three groups: less than 50 years, 93% +/- 5%; 50 to 59 years, 92% +/- 4%; more than 60 years, 87% +/- 4% (P = not significant). CONCLUSION Increased virulence of aortic disease, smaller aortic size, and more progressive infrainguinal disease may all negatively impact the results of ABF in younger patients. Although 5-year results are acceptable, increased caution is warranted in the routine application of ABF in young patients without limb-threatening ischemia.

Back to basics: Use of fresh cadavers in vascular surgery training

BACKGROUND Surgical trainees face many obstacles in learning basic surgical anatomy and technique. Pressure for quicker operative times, introduction of an 80-hour work week, rising numbers of endovascular procedures replacing open surgery, and the presence of fellowship training programs can limit resident exposure not only to surgical skills, but to attending faculty as well. Our goal was to design a vascular exposures course using fresh frozen cadavers to promote dissection and suturing skills, foster interaction with Vascular Surgery faculty, promote teamwork between residents, and measure the satisfaction of the residents with the course. METHODS A pilot program was created with fresh frozen cadavers used to teach basic vascular surgical anatomy and operating skills to junior and mid-level general surgery residents. The course was organized by the Department of General Surgery and the Division of Vascular Surgery. Trainees completed a general questionnaire and evaluation at the completion of the course. RESULTS Forty-five general surgery residents participated in 6 independent sessions offered over a 24-month period. Data from 2 questionnaires were entered into a spreadsheet and analyzed. Eighty-five percent of residents found the course met their expectations. Fresh frozen cadaver material was found optimal by all participants. Forty-four of 45 (97.8%) residents rated the educational value of the course with a perfect score and would recommend the course to others. CONCLUSION Fresh frozen cadavers provide an excellent opportunity to teach basic open vascular surgery principles while fostering interaction with faculty. Sharing cadavers between multiple disciplines can help with cost containment.

Oxidative stress contributes to the augmented exercise pressor reflex in peripheral arterial disease patients

•  Peripheral arterial disease (PAD) is a common and debilitating condition linked with heightened risk of cardiovascular mortality. •  Dynamic exercise elicits augmented blood pressure responses in PAD that could put the patient at risk for adverse event but the underlying mechanisms are unknown. •  The exercise pressor reflex is comprised of group III and group IV muscle afferents that increase their discharge in response to mechanical and/or chemical stimulation. •  In this study, we demonstrate that mechanically sensitive muscle afferents cause augmented reflex elevations in blood pressure during dynamic plantar flexion exercise in PAD. These responses occur prior to claudication pain, are related to disease severity and can be partly reduced by acute antioxidant infusion.

Monitoring of fetal radiation exposure during pregnancy.

BACKGROUND One unique concern of vascular surgeons and trainees is radiation exposure associated with increased endovascular practice. The safety of childbearing is a particular worry for current and future women in vascular surgery. Little is known regarding actual fetal radiation exposure. This multi-institutional study aimed to evaluate the radiation dosages recorded on fetal dosimeter badges and compare them to external badges worn by the same cohort of women. METHODS All women who declared pregnancy with potential radiation exposure were required to wear two radiation monitors at each institution, one outside and the other inside the lead apron. Maternal (external) and fetal monitor dosimeter readings were analyzed. Maternal radiation exposures prior to, during, and postpregnancy were also assessed to determine any associated behavior modification. RESULTS Eighty-one women declared pregnancy from 2008 to 2011 and 32 had regular radiation exposure during pregnancy. Maternal whole-body exposures ranged from 21-731 mrem. The average fetal dosimeter recordings for the cohort rounded to zero. Only two women had positive fetal dosimeter recordings; one had a single recording of 3 mrem and the other had a single recording of 7 mrem. There was no significant difference between maternal exposures prior to, during, and postpregnancy. CONCLUSIONS Lack of knowledge of fetal radiation exposure has concerned many vascular surgeons, prompting them to wear double lead aprons during pregnancy, and perhaps prevented numerous other women from entering the field. Our study showed negligible radiation exposure on fetal monitoring suggesting that with the appropriate safety precautions, these concerns may be unwarranted.

Endovascular as an Open Adjunct: Use of Hybrid Endovascular Treatment in the SFA

While open or endovascular techniques for treatment of the superficial femoral artery continue to dominate the care of most patients, there are clearly patients who benefit from a combination of these approaches. Typically these patients require treatment of more than a single level of disease. In these cases, endovascular treatment of one level is combined with surgical treatment at a second level of disease. Most commonly these involve surgical treatment of common femoral artery disease with endovascular treatment of the superficial femoral artery on either side or endovascular treatment of the superficial femoral artery combined with distal origin vein bypass. These approaches allow care to be delivered in a single setting, avoiding the issues of staged procedures. Although the published results from hybrid treatment are limited, the obvious patient benefit ensures that these techniques will continue to be important for vascular patient care.

The history of radiation use in medicine

INTRODUCTION Radiation was discovered just slightly more than a century ago, with a profound effect on both industry and medicine. Several notable scientists were key in bringing radiation to the forefront. METHODS Historical review of scientists who played key roles in the discovery of radiation and its use in medicine are reviewed. RESULTS Wilhelm Roentgen, Henri Becquerel, and Marie and Pierre Curies work is reviewed. The field of radiation safety was born to protect those handling radiation in addition to patients who received radiation for medical purposes. CONCLUSION Radiation use in medicine continues to evolve after notable discoveries by Nobel Prize-winning scientists.

National variation in preoperative imaging, carotid duplex ultrasound criteria, and threshold for surgery for asymptomatic carotid artery stenosis

OBJECTIVE Carotid endarterectomy (CEA) for asymptomatic carotid artery stenosis is among the most common procedures performed in the United States. However, consensus is lacking regarding optimal preoperative imaging, carotid duplex ultrasound criteria, and ultimately, the threshold for surgery. We sought to characterize national variation in preoperative imaging, carotid duplex ultrasound criteria, and threshold for surgery for asymptomatic CEA. METHODS The Society for Vascular Surgery Vascular Quality Initiative (VQI) database was used to identify all CEA procedures performed for asymptomatic carotid artery stenosis between 2003 and 2014. VQI currently captures 100% of CEA procedures performed at >300 centers by >2000 physicians nationwide. Three analyses were performed to quantify the variation in (1) preoperative imaging, (2) carotid duplex ultrasound criteria, and (3) threshold for surgery. RESULTS Of 35,695 CEA procedures in 33,488 patients, the study cohort was limited to 19,610 CEA procedures (55%) performed for asymptomatic disease. The preoperative imaging modality used before CEA varied widely, with 57% of patients receiving a single preoperative imaging study (duplex ultrasound imaging, 46%; computed tomography angiography, 7.5%; magnetic resonance angiography, 2.0%; cerebral angiography, 1.3%) and 43% of patients receiving multiple preoperative imaging studies. Of the 16,452 asymptomatic patients (89%) who underwent preoperative duplex ultrasound imaging, there was significant variability between centers in the degree of stenosis (50%-69%, 70%-79%, 80%-99%) designated for a given peak systolic velocity, end diastolic velocity, and internal carotid artery-to-common carotid artery ratio. Although 68% of CEA procedures in asymptomatic patients were performed for an 80% to 99% stenosis, 26% were performed for a 70% to 79% stenosis, and 4.1% were performed for a 50% to 69% stenosis. At the surgeon level, the range in the percentage of CEA procedures performed for a <80% asymptomatic carotid artery stenosis is from 0% to 100%. Similarly, at the center level, institutions range in the percentage of CEA procedures performed for a <80% asymptomatic carotid artery stenosis from 0% to 100%. CONCLUSIONS Despite CEA being an extremely common procedure, there is widespread variation in the three primary determinants-preoperative imaging, carotid duplex ultrasound criteria, and threshold for surgery-of whether CEA is performed for asymptomatic carotid stenosis. Standardizing the approach to care for asymptomatic carotid artery stenosis will mitigate the significant downstream effects of this variation on health care costs.

Renal vasoconstriction is augmented during exercise in patients with peripheral arterial disease

Peripheral arterial disease (PAD) patients have augmented blood pressure increases during exercise, heightening their cardiovascular risk. However, it is unknown whether patients have exaggerated renal vasoconstriction during exercise and if oxidative stress contributes to this response. Eleven PAD patients and 10 controls (CON) performed 4‐min mild, rhythmic, plantar flexion exercise of increasing intensity (0.5–2 kg) with each leg (most and least affected in PAD). Eight patients also exercised with their most affected leg during ascorbic acid (AA) infusion. Renal blood flow velocity (RBFV; Doppler ultrasound), mean arterial blood pressure (MAP; Finometer), and heart rate (HR; electrocardiogram [ECG]) were measured. Renal vascular resistance (RVR), an index of renal vasoconstriction, was calculated as MAP/RBFV. Baseline RVR and MAP were similar while HR was higher in PAD than CON (2.08 ± 0.23 vs. 1.87 ± 0.20 au, 94 ± 3 vs. 93 ± 3 mmHg, and 72 ± 3 vs. 59 ± 3 bpm [P < 0.05] for PAD and CON, respectively). PAD had greater RVR increases during exercise than CON, specifically during the first minute (PAD most: 26 ± 5% and PAD least: 17 ± 5% vs. CON: 3 ± 3%; P < 0.05). AA did not alter baseline RVR, MAP, or HR. AA attenuated the augmented RVR increase in PAD during the first minute of exercise (PAD most: 33 ± 4% vs. PAD most with AA: 21 ± 4%; P < 0.05). In conclusion, these findings suggest that PAD patients have augmented renal vasoconstriction during exercise, with oxidative stress contributing to this response.