Detection of subclinical hemorrhage using electrical impedance: a porcine study

OBJECTIVE

Analyze the performance of electrical impedance tomography (EIT) in an innovative porcine model of subclinical hemorrhage and investigate associations between EIT and hemodynamic trends.

APPROACH

Twenty-five swine were bled at slow rates to create an extended period of subclinical hemorrhage during which the animal's heart rate (HR) and blood pressure (BP) remained stable from before hemodynamic deterioration, where stable was defined as < 15% decrease in BP and < 20% increase in HR - i.e. hemorrhages were hidden from standard vital signs of HR and BP. Continuous vital signs, photo-plethysmography, and continuous non-invasive EIT data were recorded and analyzed with the objective of developing an improved means of detecting subclinical hemorrhage - ideally as early as possible.

MAIN RESULTS

Best area-under-the-curve (AUC) values from comparing bleed to no-bleed epochs were 0.96 at a 80 ml bleed (~15.4 minutes) using an EIT-data-based metric and 0.79 at a 120 ml bleed (~23.1 minutes) from invasively measured BP - i.e. the EIT-data-based metric achieved higher AUCs at earlier points compared to standard clinical metrics without requiring image reconstructions.

SIGNIFICANCE

In this clinically relevant porcine model of subclinical hemorrhage, EIT appears to be superior to standard clinical metrics in early detection of hemorrhage.

Procedure-Associated Costs and Mid-Term Outcomes of Endovascular Zone 0 and Zone 1 Aortic Arch Repair

BACKGROUND

Thoracic endovascular aortic repair (TEVAR) of proximal aortic arch pathology provides a less-invasive treatment option for high-risk patients ineligible for open arch reconstruction. However, the fiscal impact of these techniques remains unclear. Therefore, our objective was to characterize the mid-term outcomes after Zone 0 and Zone 1 TEVAR and describe the associated technical costs, revenues, and net margins at a single tertiary medical center.

METHODS

We examined all patients who underwent TEVAR between April 2011 and August 2019 via retrospective chart review. Patients were categorized by proximal endograft extent to identify Zone 0 or Zone 1 repairs. Procedural characteristics and outcomes were described. Technical costs, revenues, and margins were obtained from the hospital finance department.

RESULTS

We identified 10 patients (6 Zone 0, 4 Zone 1) who were denied open arch reconstruction. Patients were predominantly female (n = 8; 80%) and the mean age was 72.8 ± 5.5 years. TEVAR was performed in 5 asymptomatic patients, urgently in 3 symptomatic patients, and emergently in 2 ruptured patients. TEVAR plus extra-anatomic bypass was performed in 4 patients. Another 4 patients also received parallel stent-grafting while 1 patient received a branched thoracic endograft and yet another an in-situ laser fenestration followed by branch stent grafting. Within the 30-day postoperative period, 1 patient experienced stroke and 1 patient died. Bypass and branch vessel patency were 100% through the duration of follow-up (mean 19.3 months). Mean total technical cost associated with all procedures or repair stages was $105,164 ± $59,338 while mean net technical margin was -$25,055 ± $18,746. The net technical margin was negative for 9 patients.

CONCLUSIONS

Endovascular repair of the proximal aortic arch is associated with good mid-term outcomes in patients considered too high-risk for open repair. However, reimbursement does not adequately cover treatment cost, with net technical margins being negative in nearly all cases. To remain financially sustainable, efforts should be made to both optimize aortic arch TEVAR delivery as well as advocate for reimbursement commensurate with associated costs.

Comparison of Social Media Utilization Among Vascular Surgeons, Interventional Cardiologists, and Interventional Radiologists at Academic Training Institutions

BACKGROUND

Social media platforms, especially Twitter, are increasingly utilized across medical practice, education, and research. However, little is known about differences in social media use among physicians of varying specialties and its impact on recruitment of trainees. Our objective was to describe differences in social media use among vascular interventional proceduralists at academic training institutions.

METHODS

We identified institutions with training programs in vascular surgery (VS), interventional radiology (IR), and interventional cardiology (IC). Faculty providers were identified in each specialty at these institutions. A standardized search was used to identify non-anonymous social media profiles on Facebook, Instagram, and Twitter in September 2019. Influencers were defined as physicians with more than 1,000 Twitter followers. Follow ratio was defined as the number of followers divided by the number of accounts followed. Between-specialty differences were analyzed.

RESULTS

A total of 1,330 providers (n = 454 VS, n=451 IR, n = 425 IC) were identified across 47 institutions in 27 states. Across all physicians, a minority of providers utilize social media (Facebook: 24.9%, n = 331; Instagram: 10.8%, n = 143; Twitter: 18.0%, n = 240). VS were significantly more likely to use Instagram (P = 0.001) but there was not a significant difference in utilization of Facebook and Twitter. Among Twitter users, VS had fewer followers on average (median 178, inter-quartile range [IQR] 39-555) than IR (median 272, IQR 50-793, P = 0.26) and IC (median 286, IQR 71-1257, P = 0.052). IC were most likely to be influencers (30.9%, n = 25) followed by IR (17.9%, n = 15) and VS (10.7%, n = 8, P = 0.006). On average, interventional cardiologists had the highest follow ratio (mean 4.9 ± 7.1) compared to interventional radiologists (mean 3.2 ± 5.5) and vascular surgeons (mean 2.5 ± 3.3, P < 0.001).

CONCLUSION

A minority of academic vascular interventional proceduralists utilize social media in a non-anonymous manner. On Twitter, interventional cardiologists are most likely to be influencers based on number of followers and, on average, have the highest follow ratio. Vascular surgeons could potentially benefit from pursuing greater influence and visibility on social media as a means to recruit trainees.

Stress testing before abdominal aortic aneurysm repair does not lead to a reduction in perioperative cardiac events

OBJECTIVE

Stress testing is often used before abdominal aortic aneurysm (AAA) repair. Whether stress testing leads to a reduction in cardiac events after AAA repair has remained unclear. Our objective was to study the national stress test usage rates and compare the perioperative outcomes between centers with high and low usage of stress testing.

METHODS

We used the Vascular Quality Initiative to study patients who had undergone elective endovascular AAA repair (EVAR) or open AAA repair (OAR). We measured the usage rates of stress testing across centers and compared the Vascular Study Group of New England cardiac risk index (VSG-CRI) among patients who had and had not undergone preoperative stress testing. We determined the rate of major adverse cardiac events (MACE), a composite of perioperative myocardial infarction, stroke, heart failure exacerbation, and death across the centers. We compared the MACE and 1-year mortality between the centers in the highest quintile of stress test usage and the lowest quintile.

RESULTS

We studied 43,396 EVAR patients and 8935 OAR patients across 324 centers. The median proportion of stress test usage across centers before EVAR was 35.9% and varied from 10.2% (5th percentile) to 73.7% (95th percentile), with similar variability for OAR (median, 57.9%; 5th percentile, 13.0%; 95th percentile, 86.0%). The mean VSG-CRI for the EVAR group with preoperative stress testing was 5.6 ± 2.1 compared with 5.4 ± 2.1 (P < .001) for the EVAR group without preoperative stress testing. The findings were similar for OAR, with a VSG-CRI of 5.1 ± 2.0 vs 4.8 ± 2.1 (P < .001) for those with and without preoperative stress testing, respectively. The rate of MACE was 1.8% after EVAR and 11.6% after OAR. The 1-year mortality was 4.6% for EVAR and 6.6% for OAR. The centers in the highest quintile of stress testing had a higher adjusted likelihood of MACE after both EVAR (odds ratio [OR], 1.78; 95% confidence interval [CI], 1.37-2.30) and OAR (OR, 1.99; 95% CI, 1.53-2.59) but similar 1-year mortality (EVAR: OR, 1.18; 95% CI, 1.02-1.37; OAR: OR, 0.87; 95% CI, 0.65-1.17) compared with the centers in the lowest quintile. The VSG-CRI was not different between the high stress test centers (EVAR, 5.5 ± 2.1; OAR: 5.0 ± 2.0), and low stress test centers (EVAR, 5.5 ± 2.1; P = .403; OAR, 4.9 ± 2.0; P = .563).

CONCLUSIONS

Stress test usage before AAA repair varied widely across Vascular Quality Initiative centers despite similar patient risk profiles. No reduction was observed in MACE or 1-year mortality among centers with high stress test usage. The value of routine stress testing before AAA repair should be reconsidered, and stress testing should be used more selectively, given these findings and the associated costs of widespread testing.

Medicare costs for endovascular abdominal aortic aneurysm treatment in the Vascular Quality Initiative

BACKGROUND

Reintervention after endovascular repair (EVR) of abdominal aortic aneurysms is common. However, the cumulative financial impact of reintervention after EVR on a national scale is poorly defined. Our objective was to describe the cost to Medicare for aneurysm treatment (EVR plus reinterventions) among a cohort of patients with known follow-up for 5 years after repair.

METHODS

We identified patients who underwent EVR within the Vascular Quality Initiative who were linked to their respective Medicare claims file (n = 13,995). We excluded patients who underwent EVR after September 30, 2010, and those who had incomplete Medicare coverage (n = 12,788). The remaining cohort (n = 1207) had complete follow-up until death or 5 years (Medicare data available through September 30, 2015). We then obtained and compiled the corresponding Medicare reimbursement data for the index EVR hospitalization and all subsequent reinterventions.

RESULTS

We studied 1207 Medicare patients who underwent EVR and had known follow-up for reinterventions for 5 years. The mean age was 76.2 years (±7.1 years), 21.6% of patients were female, and 91.1% of procedures were elective. The Kaplan-Meier reintervention rate at 5 years was 18%. Among patients who underwent reintervention, 154 (73.7%) had a single reintervention, 40 (19.1%) had two reinterventions, and 15 (7.2%) had three or more reinterventions. The median cost to Medicare for the index EVR hospitalization was $25,745 (interquartile range, $21,131-$28,774). The median cost for subsequent reinterventions was $22,165 (interquartile range, $17,152-$29,605). The cumulative cost to Medicare of aneurysm treatment (EVR plus reinterventions) increased in a stepwise fashion among patients who underwent multiple reinterventions, with each reintervention being similar in cost to the index EVR.

CONCLUSIONS

The overall cost incurred by Medicare to reimburse for each reintervention after EVR is roughly the same as for the initial procedure itself, meaning that Medicare cost projections would be greater than $100,000 for any individual who undergoes an EVR with three reinterventions. The long-term financial impact of EVR must be considered by surgeons, patients, and healthcare systems alike as these cumulative costs may hinder the fiscal viability of an EVR-first therapeutic approach and highlight the need for judicious patient selection paradigms.

Outcomes of Innominate Artery Revascularization Through Endovascular, Hybrid, or Open Approach

BACKGROUND

Atherosclerotic disease of the innominate artery (IA) is rare and can lead to cerebral, upper extremity, and vertebral steal symptoms. Nonocclusive lesions can be treated with endovascular interventions, often with a hybrid approach while performing a right carotid endarterectomy (RCEA). Calcified IA lesions have a high risk of embolization to bilateral cerebral hemispheres. Occlusive lesions may require treatment through a median sternotomy and bypass. The purpose of our study is to review our short-term and long-term outcomes of IA revascularization.

METHODS

Our operative database was used to identify patients who underwent IA revascularization between January 1998 and December 2018. Patients who underwent innominate artery stenting (IAS), combined with RCEA and IAS as well as aortoinnominate bypass (AIB), were identified. Our primary end points were freedom from neurologic event, all-cause mortality, and need for reintervention.

RESULTS

Thirty-three patients (18 females [55%]) who underwent IA revascularization were identified. Average age was 67 ± 8 years, and mean clinical follow-up was 51 ± 21 months. Most patients (30 [91%]) were on a statin and antiplatelet therapy. Twenty-one patients (64%) were symptomatic. Twelve patients (36%) were asymptomatic and underwent combined RCEA with retrograde IAS for critical right carotid stenosis and IA stenosis. Preoperative imaging included a carotid duplex and computed tomography angiography. Eighteen patients (55%) underwent RCEA + IAS, 11 patients (33%) underwent isolated IAS, and 4 patients (12%) underwent AIB. In our attempt to protect bilateral hemispheres during IAS for heavily calcified lesions, we used right common carotid artery (CCA) clamping although open exposure and left CCA embolic protection filter was placed through transfemoral approach. Patients who underwent AIB had chronic heavily calcified IA occlusions or occluded IA stents with failed endovascular interventions. Perioperative stroke rate was 3%, involving 1 patient who developed reperfusion syndrome after RCEA + IAS. Perioperative mortality was 0%. Long-term stroke rate was 0%, and long-term mortality was 15% (5 of 33) because of cardiac disease. Overall restenosis rate was 9%, involving 3 patients who required secondary interventions for IA in-stent restenosis.

CONCLUSIONS

IA interventions through a hybrid approach or an open approach are safe, with acceptable perioperative stroke and mortality rates. Long-term patency of these interventions is acceptable. Bilateral cerebral embolic protection can be accomplished by clamping the right CCA through an open exposure and placing a filter in the left CCA through a transfemoral approach. Patients undergoing IAS appear to have a higher rate of restenosis compared with AIB, and therefore, close follow-up with noninvasive imaging is recommended.

Online Ratings for Vascular Interventional Proceduralists Vary by Physician Specialty

BACKGROUND

Multiple specialties offer vascular interventional care, creating potential competition for referrals and procedures. At the same time, patient/consumer ratings have become more impactful for physicians who perform vascular procedures. We hypothesized that there are differences in online ratings based on specialty.

METHODS

We used official program lists from the Association for Graduate Medical Education to identify institutions with training programs in integrated vascular surgery (VS), integrated interventional radiology (IR), and interventional cardiology (IC). Faculty providers were identified in each specialty at these institutions. A standardized search was performed to collect online ratings from Vitals.com, Healthgrades.com, and Google.com as well as from online demographics. Between specialty differences were analyzed using chi-squared and analysis of variance tests as appropriate. Multivariable linear regression was used to identify factors associated with review volume and star rating.

RESULTS

A total of 1,330 providers (n = 454 VS, n = 451 IR, n = 425 IC) were identified across 47 institutions in 27 states. VS (55.5%-69.4%) and IC (63.8%-71.1%) providers were significantly more likely to have reviews than IR (28.6%-48.8%) providers across all online platforms (P < 0.001 for all websites). Across all platforms, IC providers were rated significantly higher than VS and IR providers. Multivariable regression showed that provider specialty and additional time in practice were associated with higher review volume. In addition to specialty, review volume was associated with star rating as those physicians with more reviews tended to have a higher rating.

CONCLUSIONS

On average, vascular surgeons have more reviews and are more highly rated than interventional radiologists but tend to have fewer reviews and lower ratings than interventional cardiologists. VS providers may benefit from encouraging patients to file online reviews, especially in competitive markets.

Longitudinal Spending on Endovascular and Open Abdominal Aortic Aneurysm Repair

BACKGROUND

Endovascular repair (EVR) has replaced open surgery as the procedure of choice for patients requiring elective abdominal aortic aneurysm (AAA) repair. Long-term outcomes of the 2 approaches are similar, making the relative cost of caring for these patients over time an important consideration.

METHODS AND RESULTS

We linked Medicare claims to Vascular Quality Initiative registry data for patients undergoing elective EVR or open AAA repair from 2004 to 2015. The primary outcome was Medicare's cumulative disease-related spending, adjusted to 2015 dollars. Disease-related spending included the index operation and associated hospitalization, surveillance imaging, reinterventions (AAA-related and abdominal wall procedures), and all-cause admissions within 90 days. We compared the incidence of disease-related events and cumulative spending at 90 days and annually through 7 years of follow-up. The analytic cohort comprised 6804 EVR patients (median follow-up: 1.85 years; interquartile range: 0.82-3.22 years) and 1889 open repair patients (median follow-up: 2.62 years; interquartile range: 1.13-4.80 years). Spending on index surgery was significantly lower for EVR (median [interquartile range]: $25 924 [$22 280-$32 556] EVR versus $31 442 [$24 669-$40 419] open; P<0.001), driven by a lower rate of in-hospital complications (6.6% EVR versus 38.0% open; P<0.001). EVR patients underwent more surveillance imaging (1.8 studies per person-year EVR versus 0.7 studies per person-year open; P<0.001) and AAA-related reinterventions (4.0 per 100 person-years EVR versus 2.1 per 100 person-years open; P=0.041). Open repair patients had higher rates of 90-day readmission (12.9% EVR versus 17.8% open; P<0.001) and abdominal wall procedures (0.6 per 100 person-years EVR versus 1.5 per 100 person-years open; P<0.001). Overall, EVR patients incurred more disease-related spending in follow-up ($7355 EVR versus $2706 open through 5 years). There was no cumulative difference in disease-related spending between surgical groups by 5 years of follow-up (-$33 EVR [95% CI: -$1543 to $1476]).

CONCLUSIONS

We observed no cumulative difference in disease-related spending on EVR and open repair patients 5 years after surgery. Generalized recommendations about which approach to offer elective AAA patients should not be based on relative cost.

Patient information sources when facing repair of abdominal aortic aneurysm

OBJECTIVE

Shared medical decision making is most important when there are competing options for repair such as in treatment of abdominal aortic aneurysm (AAA). We sought to understand the sources of patients' pre-existing knowledge about AAA to better inform treating physicians about patients' needs for preoperative counseling.

METHODS

We performed a multicenter survey of patients facing AAA repair at 20 Veterans Affairs hospitals across the United States as part of the Preferences for Open Versus Endovascular Repair of AAA study. A validated survey instrument was administered to examine the sources of information available and commonly used by patients to learn about their repair options. The survey was administered by study personnel before the patient had any interaction with the vascular surgeon because survey data were collected before the vascular clinic visit.

RESULTS

Preliminary analysis of data from 99 patients showed that our cohort was primarily male (99%) and elderly (mean age 73 years). Patients commonly had a history of hypertension (86%), prior myocardial infarction (32%), diabetes (32%), and were overweight (58%). Patients arrived at their surgeon's office appointment with limited information. A majority of patients (52%) reported that they had not talked to their primary care physician at all about their options for AAA repair, and one-half (50%) reported that their view of the different surgical options had not been influenced by anyone. Slightly less than one-half of patients reported that they did not receive any information about open surgical aneurysm repair and endovascular aortic aneurysm repair (41% and 37%, respectively). Few patients indicated using the internet as their main source of information about open surgical aneurysm repair and endovascular aortic aneurysm repair (10% and 11%, respectively).

CONCLUSIONS

Patients are commonly referred for AAA repair having little to no information regarding AAA pathology or repair options. Fewer than one in five patients searched the internet or had accessed other sources of information on their own. Most vascular surgeons should assume that patients will present to their first vascular surgery appointment with minimal understanding of the treatment options available to them.

Coil embolization of an aberrant posterior tibial artery pseudoaneurysm after total knee arthroplasty

Arterial injury is a recognized but rare complication of total knee arthroplasty. These injuries, however, can be exceptionally devastating and potentially result in limb loss. Presentation may be delayed with symptoms associated with mass effect rather than with ischemia. We describe treatment of a patient with presentation delayed 2 weeks. In addition, the patient's arterial branch pattern demonstrated aberrant anatomy with high takeoff of the posterior tibial artery. This patient was successfully treated with transcatheter coil embolization. The current treatment options and published literature are reviewed.

Characterizing Reimbursements for Medicare Patients Receiving Endovascular Abdominal Aortic Aneurysm Repair at Vascular Quality Initiative Centers

BACKGROUND

Endovascular aortic aneurysm repair (EVR) has a major financial impact on health care systems. We characterized reimbursement for index EVR hospitalizations among Medicare beneficiaries having surgery at Vascular Quality Initiative (VQI) centers.

METHODS

We linked Medicare claims to VQI clinical registry data for patients undergoing EVR from 2003 to 2015. Analysis was limited to patients fully covered by fee-for-service Medicare parts A and B in the year of their operation and assigned a corresponding diagnosis-related group for EVR. The primary outcome was Medicare's reimbursement for inpatient hospital and professional services, adjusted to 2015 dollars. We performed descriptive analysis of reimbursement over time and univariate analysis to evaluate patient demographics, clinical characteristics, procedural variables, and postoperative events associated with reimbursement. This informed a multilevel regression model used to identify factors independently associated with EVR reimbursement and quantify VQI center-level variation in reimbursement.

RESULTS

We studied 9,403 Medicare patients who underwent EVR at VQI centers during the study period. Reimbursements declined from $37,450 ± $9,350 (mean ± standard deviation) in 2003 to $27,723 ± $10,613 in 2015 (test for trend, P < 0.001). For patients experiencing a complication (n = 773; 8.2%), mean reimbursement for EVR was $44,858 ± $23,825 versus $28,857 ± $9,258 for those without complications (P < 0.001). Intestinal ischemia, new dialysis requirement, and respiratory compromise each doubled Medicare's average reimbursement for EVR. After adjusting for diagnosis-related group, several patient-level factors were independently associated with higher Medicare reimbursement; these included ruptured abdominal aortic aneurysm (+$2,372), additional day in length of stay (+$1,275), and being unfit for open repair (+$501). Controlling for patient-level factors, 4-fold variation in average reimbursement was seen across VQI centers.

CONCLUSIONS

Reimbursement for EVR declined between 2003 and 2015. We identified preoperative clinical factors independently associated with reimbursement and quantified the impact of different postoperative complications on reimbursement. More work is needed to better understand the substantial variation observed in reimbursement at the center level.