Fabrication of an in-plane SU-8 cantilever with integrated strain gauge for wall shear stress measurements in fluid flows.

We present a cantilever fabricated from the polymer SU-8 for the measurement of wall shear stress in fluid flows. The pressure induced deflection of the cantilever, measured using a calibrated and integrated nichrome strain gauge, can be related to the wall shear stress on the surface. The initial degree of curvature of the cantilever can be controlled via the exposure dose, which allows a small positive deflection to be achieved, and so minimises the intrusion into the flow. Wind tunnel testing results show a sensitivity greater than 2.5 mV/Pa, with a shear stress of 0.38 Pa and excitation of 1 V

Response by Arora et al to Letter Regarding Article, "Twenty Year Trends and Sex Differences in Young Adults Hospitalized With Acute Myocardial Infarction: The ARIC Community Surveillance Study"

In Response: In a recent investigation from ARIC (Atherosclerosis Risk in Communities Study ), we analyzed 28 732 acute myocardial infarction (AMI) hospitalizations sampled among black and white patients aged 35 to 74 years. We observed that an increasing percentage of the AMI hospitalizations from 1995 to 2014 were young patients (35–54 years), and that the increase was especially pronounced among women. We also noted that young women with AMI were less likely to receive guideline-based therapies compared to young men

Recurrent Acute Decompensated Heart Failure Admissions for Patients With Reduced Versus Preserved Ejection Fraction (from the Atherosclerosis Risk in Communities Study)

Hospitals are required to report all-cause 30-day readmissions for patients discharged with heart failure. Same-cause readmissions have received less attention but may differ for heart failure with reduced ejection fraction (HFrEF) versus heart failure with preserved ejection fraction (HFpEF). The ARIC study began abstracting medical records for cohort members hospitalized with acute decompensated heart failure (ADHF) in 2005. ADHF was validated by physician review, with HFrEF defined by ejection fraction <50%. Recurrent admissions for ADHF were analyzed within 30 days, 90 days, 6 months, and 1 year of the index hospitalization using repeat-measures Cox regression models. All recurrent ADHF admissions per patient were counted rather than the more typical analysis of only the first occurring readmission. From 2005 to 2014, 1,133 cohort members survived at least 1 hospitalization for ADHF and had ejection fraction recorded. Half were classified as HFpEF. Patients with HFpEF were more often women and had more co-morbidities. The overall ADHF readmission rate was greatest within 30 days of discharge but was higher for patients with HFrEF (115 vs 88 readmissions per 100 person-years). After adjustments for demographics, year of admission, and co-morbidities, there was a trend for higher ADHF readmissions with HFrEF, relative to HFpEF, at 30 days (hazard ratio [HR] 1.41, 95% confidence interval [CI] 0.92 to 2.18), 90 days (HR 1.39, 95% CI 1.05 to 1.85), 6 months (HR 1.47, 95% CI, 1.18 to 1.84), and 1 year (HR 1.42, 95% CI 1.18 to 1.70) of follow-up. In conclusion, patients with HFrEF have a greater burden of short- and long-term readmissions for recurrent ADHF

Temporal trends in prevalence and prognostic implications of comorbidities among patients with acute decompensated heart failure: The ARIC study community surveillance

Background: Patients with heart failure (HF) have multiple coexisting comorbidities. The temporal trends in the burden of comorbidities and associated risk of mortality among patients with HF with preserved ejection fraction (HFpEF) and HF with reduced ejection fraction (HFrEF) are not well established. Methods: HF-related hospitalizations were sampled by stratified design from 4 US areas in 2005 to 2014 by the community surveillance component of the ARIC study (Atherosclerosis Risk in Communities). Acute decompensated HF was classified by standardized physician review and a previously validated algorithm. An ejection fraction <50% was considered HFrEF. A total of 15 comorbidities were abstracted from the medical record. Mortality outcomes were ascertained for up to 1-year postadmission by linking hospital records with death files. Results: A total of 5460 hospitalizations (24 937 weighted hospitalizations) classified as acute decompensated HF had available ejection fraction data (53% female, 68% white, 53% HFrEF, 47% HFpEF). The average number of comorbidities was higher for patients with HFpEF versus HFrEF, both for women (5.53 versus 4.94; P<0.0001) and men (5.20 versus 4.82; P<0.0001). There was a significant temporal increase in the overall burden of comorbidities, both for patients with HFpEF (women: 5.17 in 2005-2009 to 5.87 in 2010-2013; men: 4.94 in 2005-2009 and 5.45 in 2010-2013) and HFrEF (women: 4.78 in 2005-2009 to 5.14 in 2010-2013; men: 4.62 in 2005-2009 and 5.06 in 2010-2013; P-trend<0.0001 for all). Higher comorbidity burden was significantly associated with higher adjusted risk of 1-year mortality, with a stronger association noted for HFpEF (hazard ratio [HR] per 1 higher comorbidity, 1.19 [95% CI, 1.14-1.25] versus HFrEF (HR, 1.10 [95% CI, 1.05-1.14]; P for interaction by HF type=0.02). The associated mortality risk per 1 higher comorbidity also increased significantly over time for patients with HFpEF and HFrEF, as well (P for interaction with time=0.002 and 0.02, respectively) Conclusions: The burden of comorbidities among hospitalized patients with acute decompensated HFpEF and HFrEF has increased over time, as has its associated mortality risk. Higher burden of comorbidities is associated with higher risk of mortality, with a stronger association noted among patients with HFpEF versus HFrEF

Racial Differences and Temporal Obesity Trends in Heart Failure with Preserved Ejection Fraction

BACKGROUND/OBJECTIVES: Obesity increases with age, is disproportionately prevalent in black populations, and is associated with heart failure with preserved ejection fraction (HFpEF). An “obesity paradox,” or improved survival with obesity, has been reported in patients with HFpEF. The aim of this study was to examine whether racial differences exist in the temporal trends and outcomes associated with obesity among older patients with HFpEF. DESIGN: Community surveillance of acute decompensated heart failure (ADHF) hospitalizations, sampled by stratified design from 2005 to 2014. SETTING: Atherosclerosis Risk in Communities Study (NC, MS, MD, MN). PARTICIPANTS: A total of 10,147 weighted hospitalizations for ADHF (64% female, 74% white, mean age 77 years), with ejection fraction ≥50%. MEASUREMENTS: ADHF classified by physician review, HFpEF defined by ejection fraction ≥50%. Body mass index (BMI) calculated from weight at hospital discharge. Obesity defined by BMI ≥30 kg/m2, class III obesity by BMI ≥40 kg/m2. RESULTS: When aggregated across 2005–2014, the mean BMI was higher for black compared to white patients (34 vs 30 kg/m2; P <.0001), as was prevalence of obesity (56% vs 43%; P <.0001) and class III obesity (24% vs 13%; P <.0001). Over time, the annual mean BMI and prevalence of class III obesity remained stable for black patients, but steadily increased for white patients, with annual rates statistically differing by race (P-interaction =.04 and P =.03, respectively). For both races, a U-shaped adjusted mortality risk was observed across BMI categories, with the highest risk among patients with a BMI ≥40 kg/m2. CONCLUSION: Black patients were disproportionately burdened by obesity in this decade-long community surveillance of older hospitalized patients with HFpEF. However, temporal increases in mean BMI and class III obesity prevalence among white patients narrowed the racial difference in recent years. For both races, the worst survival was observed with class III obesity. Effective strategies are needed to manage obesity in patients with HFpEF

Twenty Year Trends and Sex Differences in Young Adults Hospitalized with Acute Myocardial Infarction: The ARIC Community Surveillance Study

Background: Sex differences are known to exist in the management of older patients presenting with acute myocardial infarction (AMI). Few studies have examined the incidence and risk factors of AMI among young patients, or whether clinical management differs by sex. Methods: The Atherosclerosis Risk in Communities (ARIC) Surveillance study conducts hospital surveillance of AMI in 4 US communities (MD MN, MS and NC). AMI was classified by physician review, using a validated algorithm. Medications and procedures were abstracted from the medical record. Our study population was limited to young patients aged 35 to 54 years. Results: From 1995 to 2014, 28 732 weighted hospitalizations for AMI were sampled among patients aged 35 to 74 years. Of these, 8737 (30%) were young. The annual incidence of AMI hospitalizations increased for young women but decreased for young men. The overall proportion of AMI admissions attributable to young patients steadily increased, from 27% in 1995 to 1999 to 32% in 2010 to 2014 (P for trend=0.002), with the largest increase observed in young women. History of hypertension (59% to 73%, P for trend<0.0001) and diabetes mellitus (25% to 35%, P for trend<0.0001) also increased among young AMI patients. Compared to young men, young women presenting with AMI were more often black and had a greater comorbidity burden. In adjusted analyses, young women had a lower probability of receiving lipid-lowering therapies (relative risk [RR]=0.87; 95% confidence interval [CI], 0.80-0.94), nonaspirin antiplatelets (RR=0.83; 95% CI, 0.75-0.91), beta blockers (RR=0.96; 95% CI, 0.91-0.99), coronary angiography (RR=0.93; 95% CI, 0.86-0.99) and coronary revascularization (RR = 0.79; 95% CI, 0.71-0.87). However, 1-year all-cause mortality was comparable for women versus men (HR=1.10; 95% CI, 0.83-1.45). Conclusions: The proportion of AMI hospitalizations attributable to young patients increased from 1995 to 2014 and was especially pronounced among women. History of hypertension and diabetes among young patients admitted with AMI increased over time as well. Compared with young men, young women presenting with AMI had a lower likelihood of receiving guideline-based AMI therapies. A better understanding of factors underlying these changes is needed to improve care of young patients with AMI

Prevalence and Prognostic Significance of Mitral Regurgitation in Acute Decompensated Heart Failure: The ARIC Study

Objectives: This study investigates the prevalence and prognostic significance of mitral regurgitation (MR) in acute decompensated heart failure (ADHF) patients. Background: Few studies characterize the burden of MR in heart failure. Methods: The ARIC (Atherosclerosis Risk In Communities) study surveilled ADHF hospitalizations for residents ≥55 years of age in 4 U.S. communities. ADHF cases were stratified by left ventricular ejection fraction (LVEF): <50% and ≥50%. Odds of moderate or severe MR in patients with varying sex and race, and odds of 1-year mortality in those with higher MR severity were estimated using multivariable logistic regression. Results: From 2005 to 2014, there were 17,931 weighted ADHF hospitalizations of which 49.2% had an LVEF <50% and 50.8% an LVEF ≥50%. Moderate or severe MR prevalence was 44.5% in those with an LVEF <50% and 27.5% in those with an LVEF ≥50%. Moderate or severe MR was more likely in females than males regardless of LVEF; LVEF <50% (odds ratio [OR]: 1.21 [95% confidence interval (CI): 1.11 to 1.33]), LVEF ≥50% (OR: 1.52 [95% CI: 1.36 to 1.69]). Among hospitalizations with an LVEF ≥50%, moderate or severe MR was less likely in blacks than whites (OR: 0.72 [95% CI: 0.64 to 0.82]). Higher MR severity was independently associated with increased 1-year mortality in those with an LVEF <50% (OR: 1.30 [95% CI: 1.16 to 1.45]). Conclusions: Patients with ADHF have a significant MR burden that varies with sex and race. In ADHF patients with an LVEF <50%, higher MR severity is associated with excess 1-year mortality

Fifteen-year trends in management and outcomes of non–ST-segment–elevation myocardial infarction among black and white patients: The ARIC community surveillance study, 2000–2014

Background—Standardization of evidence-based medical therapies has improved outcomes for patients with non–ST-segment– elevation myocardial infarction (NSTEMI). Although racial differences in NSTEMI management have previously been reported, it is uncertain whether these differences have been ameliorated over time. Methods and Results—The ARIC (Atherosclerosis Risk in Communities) Community Surveillance study conducts hospital surveillance of acute myocardial infarction in 4 US communities. NSTEMI was classified by physician review, using a validated algorithm. From 2000 to 2014, 17 755 weighted hospitalizations for NSTEMI (patient race: 36% black, 64% white) were sampled by ARIC. Black patients were younger (aged 60 versus 66 years), more often female (45% versus 38%), and less likely to have medical insurance (88% versus 93%) but had more comorbidities. Black patients were less often administered aspirin (85% versus 92%), other antiplatelet therapy (45% versus 60%), b-blockers (85% versus 88%), and lipid-lowering medications (68% versus 76%). After adjustments, black patients had a 24% lower probability of receiving nonaspirin antiplatelets (relative risk: 0.76; 95% confidence interval, 0.71–0.81), a 29% lower probability of angiography (relative risk: 0.71; 95% confidence interval, 0.67–0.76), and a 45% lower probability of revascularization (relative risk: 0.55; 95% confidence interval, 0.50–0.60). No suggestion of a changing trend over time was observed for any NSTEMI therapy (P values for interaction, all >0.20). Conclusions—This longitudinal community surveillance of hospitalized NSTEMI patients suggests black patients have more comorbidities and less likelihood of receiving guideline-based NSTEMI therapies, and these findings persisted across the 15-year period. Focused efforts to reduce comorbidity burden and to more consistently implement guideline-directed treatments in this high-risk population are warranted

Epidemiology and Outcomes of Aortic Stenosis in Acute Decompensated Heart Failure: The ARIC Study

Background: Few studies characterize the epidemiology and outcomes of aortic stenosis (AS) in acute decompensated heart failure (ADHF). This study investigates the significance of AS in contemporary patients who have experienced an ADHF hospitalization. Methods: The ARIC study (Atherosclerosis Risk in Communities) surveilled ADHF hospitalizations for residents ≥55 years of age in 4 US communities. ADHF cases were stratified by left ventricular ejection fraction (LVEF). Demographic differences in AS burden and the association of varying AS severities with mortality were estimated using multivariable logistic regression. Results: From 2005 through 2014, there were 3597 (weighted n=16 692) ADHF hospitalizations of which 48.6% had an LVEF <50% and 51.4% an LVEF ≥50%. AS prevalence was 12.1% and 18.7% in those with an LVEF <50% and ≥50%, respectively. AS was less likely in Black than White patients regardless of LVEF: LVEF <50% (odds ratio [OR], 0.34 [95% CI, 0.28-0.42]); LVEF ≥50% (OR, 0.51 [95% CI, 0.44-0.59]). Higher AS severity was independently associated with 1-year mortality in both LVEF subgroups: LVEF <50% (OR, 1.16 [95% CI, 1.04-1.28]); LVEF ≥50% (OR, 1.40 [95% CI, 1.28-1.54]). Sensitivity analyses excluding severe AS patients detected that mild/moderate AS was independently associated with 1-year mortality in both LVEF subgroups: LVEF <50% (OR, 1.23 [95% CI, 1.02-1.47]); LVEF ≥50% (OR, 1.31 [95% CI, 1.14-1.51]). Conclusions: Among patients who have experienced an ADHF hospitalization, AS is prevalent and portends poor mortality outcomes. Notably, mild/moderate AS is independently associated with 1-year mortality in this high-risk population

A robust, fine pitch probe card

A new type of probe card is described which consists of inclined nickel cantilevers formed on top of a three dimensional PDMS layer. A prototype card has been built with an in-line pitch of 23 μm. The presence of a PDMS layer beneath the cantilevers creates mechanically robust probes. The probes can apply up to 100 mN contact force and be deflected up to 40 μm without damage. Typical contact resistances of less than 5 Ω against gold and 15 Ω against copper are reported. The leakage current between adjacent probes is less than 1 nA measured at 100 V