Risk factors for lower extremity vascular complications in adult patients on veno-arterial extracorporeal membrane oxygenation

OBJECTIVE

Utilization of veno-arterial extracorporeal membrane oxygenation (VA-ECMO) has increased significantly over the last decade. Prior studies have reported worse mortality for patients with vascular complications on VA-ECMO; however, these were limited by small sample size. The purpose of this study is to investigate predictive risk factors for vascular complications in VA-ECMO patients and their potential impact on mortality.

METHODS

Patients who underwent peripheral VA-ECMO from January 2011 to December 2021 were identified. Primary outcomes were lower extremity vascular complications and in-hospital mortality. Multivariate stepwise logistic regression models were used to identify predictors of vascular complications and in-hospital mortality.

RESULTS

A total of 605 VA-ECMO patients (25% female) were identified. The mean age was 56.3 ± 13 years, and 56 (10.4%) were black. In-hospital mortality was 63.8% (n = 386), and VA-ECMO ipsilateral vascular complications occurred in 72 patients (11.9%). Vascular surgical interventions (thromboembolectomy, fasciotomies, amputation, and surgical management of cannula bleeding) were required in 30 patients (41.7%). Same-side arterial and venous cannulas, cannula size, and absence of distal perfusion cannula did not increase risk of vascular complication. Multivariate analysis identified age (odds ratio, 0.948; 95% confidence interval, 0.909-0.988; P = .0116) and pre-existing peripheral arterial disease (odds ratio, 3.489; 95% confidence inteval, 1.146-10.624; P = .0278) as independent predictors of need for vascular surgery interventions. The mortality rate of patients who developed vascular complications was not significantly different compared with the mortality rate of those who did not develop vascular complications (61% vs 64%; P = .92).

CONCLUSIONS

This study represents one of the largest series to date of lower extremity vascular outcomes in patients undergoing VA-ECMO. Our results confirm the high mortality rate associated with VA-ECMO; however, vascular complications did not represent a risk factor for mortality as previously reported. Same-sided VA-ECMO cannulas, cannula size, and the presence or absence of distal perfusion cannula did not predict vascular complications. Increasing age and presence of peripheral arterial disease are independent predictors of need for vascular surgery intervention in patients on VA-ECMO.

Ankle Brachial Index Use in Peripheral Vascular Interventions for Claudication

OBJECTIVES

Ankle brachial index (ABI) is recommended as the first-line noninvasive test to establish a diagnosis of peripheral arterial disease (PAD) in claudicants (Grade 1, Level A evidence). It is also used to monitor progression of disease and assess benefit of treatment after peripheral vascular intervention (PVI). The Upper Midwest Region VQI has a unique balance of participation from vascular surgeons, interventional radiologists, and cardiologists performing PVI. We sought to identify the use of ABI and assess functional outcome of patients undergoing PVI for claudication.

METHODS

Review of the Upper Midwest Region VQI registry was performed to identify PVI done for claudication from native artery atherosclerotic occlusive disease in non-diabetic patients from 2010 to 2020. PVI performed in patients with infection, tissue loss, rest pain, bypass graft stenoses, and aneurysmal disease was excluded. Primary outcomes included ABI, ambulation status, and functional status pre- and post-PVI.

RESULTS

A total of 3787 patients (58.0% men, 42.0% female; mean age 68.4 years) who underwent 3830 procedures were identified. 2665 (69.5%) patients had ABI measured: 1803 (47.1%) patients had pre-PVI only, 190 (4.9%) patients had post-PVI only, and 862 (22.5%) patients had pre- and post-PVI ABI measured. 975 (25.5%) patients never had ABI performed. Statistical analysis of all 3787 patients found no change in ambulation (p = 0.33 - 0.95 for all comparisons) or in functional status (p = 0.42 - 0.61 for all comparisons), for all instances of ABI, or lack thereof. A significant number of patients who never had ABI measured decreased from full functional status pre-PVI to only being functional with light work post-PVI (p =0.015).

CONCLUSIONS

Despite Grade 1, level A evidence, ABI was utilized pre- and post-PVI in only 22.5% of patients undergoing PVI for claudication. Importantly, overall functional status was found to diminish significantly after PVI in those patients who never had an ABI performed. Accurately identifying patients with claudication from PAD with an ABI remains critically important before PVI. Given the lack of overall improvement in ambulation post-PVI noted in this study, identifying the patient who will benefit from PVI for claudication remains elusive.

Emergency Department Visits After Acute Aortic Syndromes

OBJECTIVES

Recent reports document a high rate of readmission after hospitalization for acute aortic syndromes (AAS) that include acute aortic dissections (AD), intramural hematomas (IMH), or penetrating aortic ulcers (PAU). We examined the rate of return to the emergency department (ED) to better understand the utilization of emergent health care services after AAS.

METHODS

Consecutive AAS patients admitted to the vascular surgery service from 2004 to 2020 were included. Patients with type A dissections, arch involvement, or chronic aortic pathology were excluded. The primary outcome was ED visits within 90 days of the original hospitalization.

RESULTS

The study included 79 subjects (62% men, 38% women; mean age, 64+14 years) with AAS (82% AD, 11% IMH, 6% PAU). A total of 54 ED visits related to the AAS occurred within 90 days of the original discharge, each of which incurred a CT angiogram. Twenty-eight (35%) subjects had a mean of 2+2 ED visits, while 51 (65%) subjects had no ED visits. Ninety percent (25/28) of the first ED visits occurred within 1 month of discharge and 53% (15/28) within one week. 17 (61%) subjects were readmitted to the hospital from the ED. Four subjects were found to have progression of AAS on imaging studies and underwent TEVAR during readmission. Comparing subjects who returned to the ED to those who did not, there were no significant differences in demographics, atherosclerotic risk factors except coronary artery disease, type of AAS, number of antihypertensive medications at admission or discharge, operative intervention, length of initial hospital stay, or discharge status. The chief complaint at the first ED visit was pain (n=17), uncontrolled hypertension (n=5), syncope (n=3), and other (n=3).

CONCLUSIONS

These data show that one in three patients with AAS returned to the ED within 90 days of initial discharge. Although returning subjects had a higher number of readmissions, few had progression of AAS that required intervention. Because the vast majority were readmitted for medical therapy, early and frequent clinic follow up may help decrease ED visits and readmissions after AAS.

The impact of pre-existing blood pressure control in patients with acute aortic dissections

OBJECTIVES

Arterial hypertension (HTN) is considered a seminal risk factor for aortic dissection (AD). The purpose of this study is to evaluate whether pre-existing blood pressure (BP) control lessens the extent of dissection and has a favorable impact on outcome of patients with acute AD.

METHODS

Consecutive acute AD patients who had at least two BPs recorded within the 12 months preceding the AD were retrospectively analyzed. The two most recent BPs were averaged and defined per published guidelines as normal (BP≤ 130/80), Stage I HTN (BP >130/80 and <139/89), or Stage 2 or greater HTN (BP > 140/90). The number of hypertensive medications (MEDs) was also used as a surrogate marker of HTN severity. Patients with known genetic causes of AD were excluded.

RESULTS

89 subjects (55% men, 45% women; mean age, 64±14 years) with acute AD (58% Stanford type A and 42% Stanford type B) were included. Two most recent BPs were recorded a mean of 5±3 and 3±2.7 months before the AD, respectively. Twenty-nine (33%) subjects had normal BP, including nine subjects with no history of HTN and on no MEDs. Sixty (67%) subjects had elevated BP, including 21 (35%) with Stage I HTN and 39 (65%) with Stage 2 HTN. Compared to subjects with normal BP, subjects with Stage 1 and Stage 2 HTN were younger (70±13 years vs 62±1 year, p = 0.01), but there were no differences in other demographics, risk factors, comorbidities, or history of drug use. There were no group differences in the distal extent of the dissections, complications requiring thoracic endograft repair, mean length of hospital stay, final discharge status, or 30-day mortality. Compared to the number of MEDs before AD, all three groups had a higher mean number of MEDs to achieve normal BP at discharge that persisted at a mean follow-up of 18±15 months.

CONCLUSIONS

These data show that approximately one-third of patients with acute AD had well controlled or no antecedent history of HTN. The degree of pre-existing HTN control had no bearing on the type or extent of AD, length of stay, or early outcome. Regardless of the state of HTN control before AD, the consistent and sustained increase in the severity of HTN after AD suggests that the dissection process has a profound and lasting effect on BP regulation. Further studies are indicated to elucidate the pathologic mechanisms involved in AD.

Representation of women in vascular surgery science and societies

OBJECTIVE

Medical schools and surgical residencies have seen an increase in the proportion of female matriculants, with 30% of current vascular surgery trainees being women over the past decade. There is widespread focus on increasing diversity in medicine and surgery in an effort to provide optimal quality of patient care and the advancement of science. The presence of gender diversity and opportunities to identify with women in leadership positions positively correlates with women choosing to enter traditionally male-dominated fields. The purpose of this study was to evaluate the representation of women in regional and national vascular surgical societies over the last 20 years.

METHODS

A retrospective review of the meeting programs of vascular surgery societies was performed. Data were collected on abstract presenters, moderators, committee members and chairs, and officers (president, president-elect, vice president, secretary, and treasurer). The data were divided into early (1999-2009) and late (2010-2019) time periods.

RESULTS

Five regional and five national societies' data were analyzed, including 139 meetings. The mean percentage of female abstract presenters increased significantly from 10.9% in the early period to 20.6% in the late period (P < .001). Female senior authors increased slightly from 8.7% to 11.5%, but this change was not statistically significant (P = .22). Female meeting moderators increased significantly from 7.8% to 17.2% (P < .001), as well as female committee members increased from 10.9% to 20.3% (P = .003). Female committee chairs increased slightly from 10.9% to 16.9%, but this difference was not statistically significant (P = .13). Female society officers increased considerably from 6.4% to 14.8%. (P = .002). Significant variation was noted between societies, with five societies (three regional and two national) having less than 10% women at the officer level in 2019. There was a wide variation noted between societies in the percentage of female abstract presenters (range, 7.6%-34.9%), senior authors (3.9%-17.9%), and meeting moderators (5.4%-40.7%).

CONCLUSIONS

Over the past two decades, there has been a significant increase in the representation of women in vascular surgery societies among those presenting scientific work, serving as meeting moderators, and serving as committee members. However, the representation of women among committee chairs, senior authors, and society leadership has not kept up pace with the increase noted at other levels. Efforts to recruit women into the field of vascular surgery as well as to support the professional development of female vascular surgeons are facilitated by the presence of women in leadership roles. Increasing the representation of women in vascular society leadership positions may be a key strategy in promoting gender diversity in the vascular surgery field.

Televascular consultation is one answer to rural vascular surgery shortage

Telemedicine provides an opportunity for virtual consultation between physicians and patients in remote locations. We sought to evaluate whether telemedicine consultation for vascular surgery can replace direct visits for patients in remote areas. Patients undergoing telemedicine consultation from 2014-2019 at the Veterans Affairs Medical Center (VAMC) with a large rural catchment area, were reviewed. Primary outcomes included diagnosis, type and number of telemedicine visits, and types of surgical procedures scheduled after initial visit. 574 patients participated in 708 out-patient telemedicine consultations conducted by four vascular surgeons and two advanced practitioners. Visits took place at 21 clinics across Minnesota (n = 305), North Dakota (n = 96), South Dakota (n = 82), Wisconsin (n = 20), and Iowa (n = 2) with an average distance of 159 miles from the VAMC. There were 429 (75%) new patient visits and 279 (25%) follow-ups. After initial telemedicine consultation, 236 (55%) patients were booked for procedures. Telemedicine is feasible for vascular surgery consultation and increases patient convenience with decreased overall travel expense and wait time. Telemedicine can be a viable solution to the shortage of vascular surgeons in the rural United States.

Vascular surgery presence in carotid endarterectomy YouTube videos

OBJECTIVE

YouTube videos have become a common resource for trainees to learn about surgical procedures. Carotid endarterectomy (CEA) is one example procedure that may be performed by multiple specialties and with a variety of techniques. Little is known about educational content and the representation of vascular surgeons in these videos. We sought to compare the educational quality of CEA YouTube videos, techniques demonstrated, and prevalence of each specialty.

METHODS

YouTube was programmatically searched for the terms "carotid endarterectomy," "carotid endarterectomy surgery," "carotid endarterectomy technique," "carotid endarterectomy CEA," and "carotid artery surgery." Videos that met inclusion criteria were analyzed for surgical technique, procedural steps, surgeon specialty, video length, and date. Videos were determined to have high-quality educational content if the video included English-language captions or narration and demonstrated key steps of the procedure: division of the common facial vein; exposure of the common, external, and internal carotid arteries; vascular control and clamping; and arteriotomy, endarterectomy, and arteriotomy closure.

RESULTS

Forty-six videos met inclusion criteria. Vascular surgery was associated with 12 (26.1%) CEA videos, cardiac surgery with 13 (28.3%), and neurosurgery with 14 (30.4%). Surgeon specialty was unknown for seven (17.4%) videos. Eight videos were high quality, of which vascular surgery was associated with three (37.5%). Conventional endarterectomy was the most common technique demonstrated, whereas a total of seven videos demonstrated eversion technique. Vascular and cardiac surgeons were more likely to demonstrate patch angioplasty than neurosurgeons, who exclusively performed primary closure (P < .05). Compared with cardiac surgeons, vascular surgeon CEA videos had more views (25,956 ± 9613 vs 1200 ± 368; P < .05) and were more likely to be published by user accounts with an academic affiliation (11 vs 6; P < .05). Vascular surgery videos were older than videos by cardiac surgeons (6.0 ± 1.1 years vs 3.0 ± 0.5 years; P < .05) and neurosurgeons (6.0 ± 1.1 years vs 3.1 ± 0.8 years; P < .05).

CONCLUSIONS

Despite more views, the field of vascular surgery is under-represented in YouTube videos demonstrating CEA. Vascular surgery videos tend to be older and make up a minority of high-quality videos. As more learners turn to YouTube for information about surgical procedures, vascular surgeons should expand their online presence through the production and collection of high-quality videos for trainees.

Pre-emptive thoracic endovascular aortic repair is unnecessary in extended type A (DeBakey type I) aortic dissections

OBJECTIVE

Pre-emptive thoracic endovascular aortic repair (TEVAR) improves late survival and limits progression of disease after type B aortic dissection, but the potential value of pre-emptive TEVAR has not been evaluated after type A dissection extending beyond the aortic arch (DeBakey type I). The purpose of this study was to compare disease progression and need for aortic intervention in survivors of acute, extended type A (ExTA) dissections after initial repair of the ascending aorta versus acute type B aortic dissections.

METHODS

Consecutive patients presenting with ExTA or type B dissections between 2011 and 2018 were studied. Forty-three patients with ExTA and 44 with type B dissections who survived to discharge and had follow-up imaging studies were included in the analysis. Study end points included progression of aortic disease (>5 mm growth or extension), need for intervention, and death.

RESULTS

The groups were not different for age, sex, atherosclerotic risk factors, or extent of dissection distal to the left subclavian artery. Following emergent ascending aortic repair, five ExTA patients (12%) underwent TEVAR within 4 months after discharge. Despite optimal medical treatment, 29 type B patients (66%) underwent early or late TEVAR (P < .001). During a mean follow-up of 38 ± 30 months, 38 ExTA patients (88%) did not require intervention-23 (53%) of whom showed no disease progression. In comparison, during a mean follow-up of 18 ± 6 months, 14 type B patients (32%) did not require intervention-nine (20%) of whom showed no disease progression (P = .003). There was one aortic-related late death in the ExTA group and two in the type B group. Compared with ExTA patients, type B patients had significantly worse intervention-free survival and intervention/growth-free survival (log rank, P < .001).

CONCLUSIONS

In contrast with type B dissections, these midterm results demonstrate that one-half of ExTA aortic dissections show no disease progression in the thoracic or abdominal aorta, and few require additional interventions. After initial repair of the ascending aorta, pre-emptive TEVAR does not seem to be justified in patients with acute, ExTA dissections.

Angiosarcoma of the abdominal aorta after endovascular aneurysm repair

Primary aortic sarcoma is a rare diagnosis that carries a poor prognosis. This case report features a 68-year-old man, treated 4 years earlier with an endovascular aortic aneurysm repair, who presented with fever, low back discomfort, and abdominal pain. Given the concern for an infected endograft, the patient underwent explantation and replacement with a cadaveric aortoiliac cryograft. Ultimately, the pathology returned as an angiosarcoma. Although endovascular aortic aneurysm repair is the gold standard for abdominal aortic aneurysm repair in patients with suitable anatomy, there are trade-offs associated with less invasive approaches compared with open approaches.

Unplanned return to operating room after lower extremity arterial bypass is an independent predictor for hospital readmission

OBJECTIVE

Hospital readmissions after surgical operations are considered serious complications and have an impact on health care-associated costs. The Centers for Medicare and Medicaid Services strongly encourage identification and ramification of factors associated with hospital readmissions after operations. Despite advances in endovascular surgery, lower extremity arterial bypass remains the "gold standard" treatment for severe, symptomatic peripheral arterial disease. The purpose of this study was to retrospectively review the factors associated with hospital readmission after lower extremity bypass surgery.

METHODS

The 2013 lower extremity revascularization-targeted American College of Surgeons National Surgical Quality Improvement Program (NSQIP) database and generalized 2013 general and vascular surgery NSQIP Participant Use Data File were used for this study. Patient, diagnosis, and procedure characteristics of patients undergoing lower extremity bypass surgery were assessed. Multivariate logistic regression analysis was used to determine independent risk factors for hospital readmission within 30 days after surgery.

RESULTS

A total of 2646 patients (65% male, 35% female) were identified in the NSQIP database who underwent lower extremity open revascularization during the year 2013. Indications for operations included tissue loss (39%), rest pain (32%), and severe claudication (25%). Preoperative ankle-brachial indices were 0.4 to 0.9 (32%) and <0.4 (16.5%). A total of 425 patients (16%) were readmitted within 30 days of index operation. Risk factors associated with readmission included wound complication (odds ratio [OR], 8.54; 95% confidence interval [CI], 6.68-10.92; P < .001), need for reoperation (OR, 5.95; 95% CI, 4.45-7.97; P < .001), postoperative myocardial infarction (OR, 2.19; 95% CI, 1.25-3.83; P = .006), wound dehiscence (OR, 8.45; 95% CI, 4.54-15.71; P < .001), organ or space surgical site infection (OR, 7.62; 95% CI, 2.89-20.14; P < .001), postoperative pneumonia (OR, 2.66; 95% CI, 1.28-5.52; P = .009), progressive renal insufficiency (OR, 4.12; 95% CI, 1.52-11.11; P = .005), superficial surgical site infection (OR, 7.37; 95% CI, 5.31-10.23; P < .001), urinary tract infection (OR, 2.67; 95% CI, 1.42-5.01; P = .002), and deep wound infection (OR, 14.0; 95% CI, 7.62-24.80; P < .001).

CONCLUSIONS

Readmission after lower extremity bypass surgery is a serious complication. Various factors put a patient at high risk for readmission. Return to the operating room, wound infection, amputation, deep venous thrombosis, and major reintervention on bypass are independent risk factors for hospital readmission. Return to the operating room is associated with a 5.95-fold increase in hospital readmission.

Modified T-Graft for Extracorporeal Membrane Oxygenation in a Patient with Small-Caliber Femoral Arteries

Extracorporeal membrane oxygenation (ECMO) is generally used as a last resort to provide cardiopulmonary support in patients whose advanced cardiac or respiratory failure does not respond to less invasive treatments. Lower-limb ischemia secondary to the large diameter of the arterial cannula is one of ECMO's major limitations: in patients who have small-caliber arteries, the cannulas can reduce native blood flow. The creation of a T-graft-a well-described technique to avoid limb ischemia-enables flow into the ECMO cannula without jeopardizing blood flow to the limb. However, leaving the graft exposed through an open groin wound can result in dislodgment, and it increases the risk of infection. We describe our modification of a conventional T-graft in an 18-year-old woman who had systolic heart failure, acute respiratory distress syndrome, and small-caliber femoral vessels. We tunneled a polytetrafluoroethylene graft inside a Dacron graft, then ran the combined graft through a subcutaneous tunnel similar to that created for a peripheral bypass. Thus, the graft was protected from environmental exposure and the risk of infection. Our technique seems safer and more secure than the original T-graft technique, and we recommend its consideration during ECMO cannulation.

Advances in renal intervention for trauma

Renal trauma is predominantly secondary to blunt trauma and is managed nonoperatively. Endovascular interventions are reserved for patients with a significant vascular injury recognized early. Renal injuries are uncommon among intra-abdominal injuries and account for a minority of injuries treated by the vascular specialist.

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.

Abstract 530: Renal Vasoconstriction is Augmented during Exercise in Peripheral Arterial Disease Patients: Contributions of Muscle Mechanoreflex and Oxidative Stress

Peripheral arterial disease (PAD) patients have augmented blood pressure increases during exercise. It is unknown whether PAD patients have greater renal vasoconstriction during exercise and how much the muscle mechanoreflex or oxidative stress contribute to this response. Eleven PAD patients and 10 healthy controls (CON) performed 4 minutes of mild, rhythmic, plantarflexion exercise of increasing intensity (0.5-2kg) with each leg (most and least affected legs for PAD). Eight PAD patients also performed exercise with their most affected leg during intravenous, high-dose, ascorbic acid (AA) infusion. Renal blood flow velocity (RBFV; Doppler ultrasound), mean arterial blood pressure (MAP; Finometer), and heart rate (HR; ECG) were measured. Renal vascular resistance (RVR), an index of renal vasoconstriction, was calculated as MAP/RBFV. Statistical analysis involved repeated measures ANOVA and paired samples t -tests. Baseline RVR and MAP were similar while HR was higher in PAD compared to CON (RVR: 2.08±0.23 vs. 1.87±0.20 arbitrary units, MAP: 94±3 vs. 93±3 mmHg, and HR: 72±3 vs. 59±3 b.min -1 (p<0.05) for PAD and CON, respectively). PAD had greater RVR increases from baseline during exercise with both the most and least affected legs compared to CON, specifically during the first minute of exercise (PAD most: 2.08±0.23 to 2.60±0.29 (+26±5%) and PAD least: 1.96±0.24 to 2.22±0.25 (+17±5%) vs. CON: 1.87±0.20 to 1.91±0.20 (+3±3%) for the first minute of exercise, both p <0.05). AA infusion did not alter baseline RVR, MAP or HR. AA attenuated the augmented RVR increase in PAD during the first minute of exercise with the most affected leg (PAD most without AA: 2.10±0.31 to 2.78±0.38 (+33±2%) vs. PAD most with AA: 1.88±0.26 to 2.23±0.26 (+21±2%) for the first minute of exercise, p <0.05). In conclusion, these findings suggest that PAD patients have augmented renal vasoconstriction during exercise, with the muscle mechanoreflex and oxidative stress contributing to this increased response.

Physiology in medicine: peripheral arterial disease

Peripheral arterial disease (PAD) is an atherosclerotic condition that can provoke symptoms of leg pain ("intermittent claudication") during exercise. Because PAD is often observed with comorbid conditions such hypertension, dyslipidemia, diabetes, cigarette smoking, and/or physical inactivity, the pathophysiology of PAD is certainly complex and involves multiple organ systems. Patients with PAD are at high risk for myocardial infarction, stroke, and all-cause mortality. For this reason, a better physiological understanding of the pathogenesis and treatment options for PAD patients is necessary and forms the basis of this Physiology in Medicine review.

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

Exaggerated blood pressure (BP) responses to dynamic exercise predict cardiovascular mortality in patients with peripheral arterial disease (PAD). However, the underlying mechanisms are unclear and no attempt has been made to attenuate this response using antioxidants. Three physiological studies were conducted in patients with PAD and controls. In Protocol 1, subjects underwent 4 min of low-intensity (0.5-2.0 kg), rhythmic plantar flexion in the supine posture. In Protocol 2, patients with PAD received high-dose ascorbic acid intravenously before exercise. In Protocol 3, involuntary exercise was conducted via electrical stimulation of the tibial nerve. The primary outcome measure was Δ mean arterial pressure (MAP) during the first 20 s of exercise (i.e. the onset of sympathoexcitation by muscle afferents). Compared to controls, patients with PAD had significantly greater ΔMAP during plantar flexion, particularly at 0.5 kg with the most affected leg (11 ± 2 vs. 2 ± 1 mmHg) as well as the least affected leg (7 ± 1 vs. 1 ± 1 mmHg). This augmented response occurred before the onset of claudication pain and was attenuated by ∼50% with ascorbic acid. Electrically evoked exercise also elicited larger haemodynamic changes in patients with PAD compared to controls. Further, the ΔMAP during 0.5 kg plantar flexion inversely correlated with the ankle-brachial index, indicating that patients with more severe resting limb ischaemia have a larger BP response to exercise. The BP response to low-intensity exercise was enhanced in PAD. Chronic limb ischaemia may sensitize muscle afferents and potentiate the BP response to muscle contraction in a dose-dependent manner.

Abstract 198: Oxidative Stress Mediates the Augmented Muscle Mechanoreflex in Peripheral Arterial Disease Patients

Background Exaggerated blood pressure (BP) responses to dynamic exercise predict cardiovascular mortality in peripheral arterial disease (PAD) patients. However, the underlying mechanisms are unclear and no attempt has been made to attenuate this response using antioxidants.

Methods Three physiological studies were conducted in PAD patients and controls. In Protocol 1, subjects underwent four minutes of low-intensity (0.5-2.0 kg), rhythmic plantar flexion in the supine posture. In Protocol 2, PAD patients received high dose ascorbic acid intravenously prior to exercise. In Protocol 3, involuntary exercise was conducted via electrical stimulation of the tibial nerve. The primary outcome measure was the change in mean arterial pressure (ΔMAP) during the first 20 seconds of exercise (i.e. when mechanoreceptors within skeletal muscle activate the sympathetic nervous system).

Results Compared to controls, PAD patients had significantly greater ΔMAP during plantar flexion, particularly at 0.5 kg of the most affected leg (11±2 vs. 2±1 mmHg) as well as the least affected leg (7±1 vs. 1±1 mmHg). This augmented response occurred before the onset of claudication pain and was attenuated by ∼50% (i.e. 6 mmHg) in the presence of ascorbic acid. Electrically evoked exercise also elicited larger hemodynamic changes in the PAD patients compared to controls. Further, the ΔMAP during 0.5 kg plantar flexion inversely correlated with the ankle-brachial index, indicating that patients with more severe resting limb ischemia had a larger BP response to exercise.

Conclusions The BP response to low intensity exercise was enhanced in PAD. Chronic limb ischemia may sensitize muscle afferents and potentiate the autonomic response to muscle contraction in a dose-dependent manner.

Determining who trains vascular surgery fellows in endovascular techniques

OBJECTIVES

Vascular surgery training has evolved from a single clinical year after general surgery training to a multi-year training program to encompass such entities as noninvasive vascular laboratory, office-based procedures, and endovascular techniques. Simultaneously, members of the vascular surgery community have had to undergo significant training to become facile with endovascular techniques. We surveyed vascular surgery trainees on the online Vascular Surgery In-Training Examination (VSITE) in 2008 and 2009 to assess who trained them in percutaneous techniques.

METHODS

Vascular surgery trainees in the Independent (2-year) and Integrated (5-year) training programs were asked to participate in a survey upon completion of the VSITE in 2008 and 2009. Examinees were asked to select whether vascular surgeons, cardiologists, or interventional radiologists trained them in carotid angioplasty and stenting (CAS), thoracic endografts (TEVAR), endovascular abdominal aortic aneurysm repair (EVAR), renal artery intervention, iliac stenting, superficial femoral artery (SFA), and tibial artery percutaneous interventions.

RESULTS

Survey response rate was 79.6% (191 of 240). Results of the survey are shown in Table I. In 2009, vascular surgeons provided more than 84% of the training to vascular surgery residents. Only six respondents had >50% of their percutaneous training with interventional radiology and two with cardiologists.

CONCLUSION

Vascular surgeons involved in resident education have been able to retrain themselves in endovascular techniques such that they are now able to provide greater than 80% of the endovascular experience to vascular surgery residents.