Hierarchical data visualization of experimental erythrocyte aggregation employing cross correlation and optical flow applications.

Appraisal of microvascular erythrocyte velocity as well as aggregation are critical features of hemorheological assessment. Examination of erythrocyte velocity-aggregate characteristics is critical in assessing disorders associated with coagulopathy. Microvascular erythrocyte velocity can be assessed using various methodologic approaches; however, the shared assessment of erythrocyte velocity and aggregation has not been well described. The purpose of this study therefore is to examine three independent erythrocyte assessment strategies with and without experimentally induced aggregation in order to elucidate appropriate analytic strategy for combined velocity/aggregation assessment applicable to in-vivo capillaroscopy. We employed a hierarchical microfluidic model combined with Bland-Altman analysis to examine agreement between three methodologies to assess erythrocyte velocity appropriate for interpretation of cinematography of in-vivo microvascular hemorheology. We utilized optical and manual techniques as well as a technique which we term transversal temporal cross-correlation (TTC) to observe and measure both erythrocyte velocity and aggregation. In general, optical, manual and TTC agree in estimation of velocity at relatively low flow rate, however with an increase in infusion rate the optical flow method yielded the velocity estimates that were lower than the TTC and manual velocity estimates. We suggest that this difference was due to the fact that slower moving particles close to the channel wall were better illuminated than faster particles deeper in the channel which affected the optical flow analysis. Combined velocity/aggregation appraisal using TTC provides an efficient approach for estimating erythrocyte aggregation appropriate for in-vivo applications. We demonstrated that the optical flow and TTC analyses can be used to estimate erythrocyte velocity and aggregation both in ex-vivo microfluidics laboratory experiments as well as in-vivo recordings. The simplicity of TTC method may be advantageous for developing velocity estimate methods to be used in the clinic. The trade-off is that TTC estimation cannot capture features of the flow based on optical flow analysis of individually tracked particles.

Analysis of endovascular therapy for femoropopliteal disease with the Supera stent.

BACKGROUND: The structural limitations of currently available laser-cut nitinol stents in the highly diseased arterial system of the lower extremity are well described. These devices are frequently used in long-segment occlusions, at the adductor hiatus, and across the knee into the popliteal artery and tibial-peroneal trunk despite concerns related to the high mobility of the knee joint and the potential for external stent compression, fractures, and occlusion. The Supera stent (Abbott Vascular, Santa Clara, Calif) was developed to provide superior radial strength, fracture resistance, and flexibility compared with laser-cut nitinol stents. This study represents the initial U.S. experience in the management of lower extremity artery atherosclerotic disease with the Supera interwoven wire stent. METHODS: Patients undergoing stent implantation in the 20-month period after the 2008 Food and Drug Administration clearance were included. Medical records, radiographic imaging, and procedural data were examined. Procedural angiograms were classified according to TransAtlantic Inter-Society Consensus criteria. Patency and limb loss rates were calculated using Kaplan-Meier analysis. RESULTS: There were 305 stents implanted in 147 patients. Clinical follow-up was a mean of 12.7 months (range, 0.2-33.7 months), and radiologic follow-up was a mean of 8.4 months (range, 0.2-26.8 months). Most patients had critical limb ischemia, with tissue loss (38.1%) or rest pain (28.6%) as the indication for intervention. Of the 147 patients, 75 (51.02%) underwent a concomitant adjunctive procedure in the treated extremity. Primary, assisted primary, and secondary patency rates at 12 months by duplex ultrasound imaging were 89.8%, 91.2%, and 93.2%, respectively, by Kaplan-Meier estimates, with a mean lesion length of 184.5 ± 131.80 mm and mean stented length of 197.5 ± 113.65 mm. Seventeen patients experienced an event requiring successful reintervention in the stented segment (13 for type I or II restenosis; four for type III). There were eight major amputations, with five of those eight having a patent stent at the time of limb sacrifice. The overall mortality was 11.6% during the study period. Knee radiography was performed in 47 patients with devices extending into the popliteal and tibial-peroneal segment, and no stent fractures were identified. CONCLUSIONS: Stenting of the superficial femoral and popliteal arteries using the Supera stent system appears to be safe and effective. The interwoven stent design may better serve areas under extreme mechanical stress. Our results with this population of highly diseased patients including very long lesion lengths are consistent with outcomes of other publications reporting the use of this device.

Optimal use of left ventriculography at the time of cardiac catheterization: a consensus statement from the Society for Cardiovascular Angiography and Interventions.

The rationale to perform left ventriculography at the time of cardiac catheterization has been little studied. The technique and frequency of use of left ventriculography vary by geographic regions, institutions, and individuals. Despite the recent publication of guidelines and appropriate use criteria for coronary angiography, revascularization, and noninvasive imaging, to date there have been no specific guidelines on the performance of left ventriculography. When left ventriculography is performed, proper technique must be used to generate high quality data which can direct patient management. The decision to perform left ventriculography in place of, or in addition to, other forms of ventricular assessment should be made taking into account the clinical context and the type of information each study provides. This paper attempts to show the role of left ventriculography at the time of coronary angiography or left heart catheterization. The recommendations in this document are not formal guidelines but are based on the consensus of this writing group. These recommendations should be tested through clinical research studies. Until such studies are performed, the writing group believes that adoption of these recommendations will lead to a more standardized application of ventriculography and improve the quality of care provided to cardiac patients. © 2014 Wiley Periodicals, Inc.

Comparison of primary percutaneous coronary intervention in patients with ST-elevation myocardial infarction during and prior to availability of an in-house STEMI system: early experience and intermediate outcomes of the HARRT program for achieving routine D2B times <60 minutes.

BACKGROUND: Over the last decade, significant advances in ST-elevation myocardial infarction (STEMI) workflow have resulted in most hospitals reporting door-to-balloon (D2B) times within the 90 min standard. Few programs have been enacted to systematically attempt to achieve routine D2B within 60 min. We sought to determine whether 24-hr in-house catheterization laboratory coverage via an In-House Interventional Team Program (IHIT) could achieve D2B times below 60 min for STEMI and to compare the results to the standard primary percutaneous coronary intervention (PCI) approach. METHODS: An IHIT program was established consisting of an attending interventional cardiologist, and a catheterization laboratory team present in-hospital 24 hr/day. For all consecutive STEMI patients, we compared the standard primary PCI approach during the two years prior to the program (group A) to the initial 20 months of the IHIT program (group B), and repeated this analysis for only CMS-reportable patients. The D2B process was analyzed by calculating workflow intervals. The primary endpoint was D2B process times, and secondary endpoints included in-hospital and 6-month cardiovascular outcomes and resource utilization. RESULTS: An IHIT program for STEMI resulted in significant reductions across all treatment intervals with an overall 57% reduction in D2B time, and an absolute reduction in mean D2B time of 71 min. There were no differences pre- and post-program implementation in regard to individual or composite components of in-hospital cardiovascular outcomes; however at 6 months, there was a reduction in cardiovascular rehospitalization after program implementation (30 vs. 5%, P < 0.01). The IHIT program resulted in a significant reduction in length-of-stay (LOS) (90 ± 102 vs. 197 ± 303 hr, P = 0.02), and critical care time (54 ± 97 vs. 149 ± 299 hr, P = 0.02). CONCLUSIONS: Availability of an in-house 24-hr STEMI team significantly decreased reperfusion time and led to improved clinical outcomes and a shorter LOS for PCI-treated STEMI patients.

Hypomagnesemia in hemodialysis patients: role of proton pump inhibitors.

BACKGROUND: Recent observations have associated hypomagnesemia with increased risk of cardiovascular morbidity and mortality in hemodialysis patients. METHODS: We did a 3-month chart review of 62 chronic hemodialysis patients at a single US hospital. All were dialyzed using a dialysate [Mg] of 0.75-1.0 mEq/l. Patients were divided into two groups: hypomagnesemic (mean predialysis plasma [Mg] <1.5 mEq/l) and non-hypomagnesemic (mean predialysis plasma [Mg] ≥1.5 mEq/l). RESULTS: All patients were male; mean age was 64.3 ± 8.7 years and the majority (73%) diabetic. 24 patients (39%) had hypomagnesemia and 38 (61%) were not hypomagnesemic. There were no significant differences between the two groups in age, diabetes status, blood pressure, duration of dialysis, plasma calcium, phosphorus, albumin, intact parathyroid hormone (PTH), dialysis adequacy (Kt/V), or dietary protein intake (as estimated by normalized protein catabolic rate, nPCR). However, use of proton pump inhibitors (PPIs) was significantly associated with hypomagnesemia (plasma [Mg] 1.48 ± 0.16 mEq/l in the PPI group vs. 1.65 ± 0.26 mEq/l in the non-PPI group, p = 0.007). Adjustment for age, diabetes status, duration of dialysis, plasma albumin, Kt/V, nPCR, and diuretic use did not affect the association between PPI use and hypomagnesemia. CONCLUSIONS: Use of PPIs in patients dialyzed using a dialysate [Mg] of 0.75-1.0 mEq/l is associated with hypomagnesemia. We suggest monitoring plasma [Mg] in patients taking PPIs, with discontinuation of the medication if possible and/or adjustment of dialysate [Mg] to normalize plasma [Mg].

SCAI expert consensus statement for infrapopliteal arterial intervention appropriate use.

Intervention to treat infrapopliteal arterial disease can be challenging because the patients' comorbidities, the anatomic variables, and the limitations of our techniques. Clinical scenarios based on anatomic and clinical variables are presented. Recommendations regarding intervention (appropriate care, may be appropriate care, rarely appropriate care) are made based on best evidence.

Preliminary results of the initial United States experience with the Supera woven nitinol stent in the popliteal artery.

BACKGROUND: Popliteal artery stenting is not routinely performed due to concerns related to the high mobility of the knee joint and the potential for external stent compression, fractures, and occlusion. Open bypass is traditionally considered the gold standard for popliteal artery atherosclerotic lesions. The Supera stent (IDEV Technologies Inc, Webster, Tex) was developed to provide superior radial strength, fracture resistance, and flexibility compared with laser-cut nitinol stents. This study represents the initial United States experience in the management of popliteal artery atherosclerotic disease with the Supera interwoven wire stent. METHODS: Patients undergoing stent implantation in the 20-month period after the 2008 Food and Drug Administration clearance were included. Medical records, radiographic imaging, and procedural data were examined. Procedural angiograms were classified according to Trans-Atlantic Inter-Society Consensus criteria. Patency and limb loss rates were calculated using Kaplan-Meier analysis. RESULTS: A total of 39 stents were placed in 34 patients due to isolated popliteal artery occlusive disease. Clinical follow-up was a mean of 12.7 months (range, 0.2-33.7 months), and radiologic follow-up was a mean of 8.4 months (range, 0-26.8 months). Most patients had critical limb ischemia (CLI), with tissue loss (38.2%) or rest pain (35.3%) as the indication for intervention. In 20 patients (58.8%), the most distal end of the stent(s) landed in the below-the-knee popliteal segment, 12 (35.3%) landed in the above-the-knee segment, and two (5.9%) landed precisely at the knee. Other than angioplasty and stenting, 47% of patients did not receive any adjuvant concomitant therapy in the treated leg. Two patients underwent concomitant atherectomy of the popliteal segment. Primary, primary assisted, and secondary patency rates by duplex ultrasound imaging were 79.2%, 88.1% and 93%, respectively, by Kaplan-Meier estimates, with a mean stented length of 12 cm. Six instances of stent occlusion were noted, and six patients were identified with hemodynamically significant in-stent stenosis. Three patients sustained limb loss (8.8%), two related to uncontrolled infections, and one due to perioperative ischemic complications (both with patent stents at the time of limb loss). The overall mortality was 8.8% during the study period. Knee roentgenography was performed in all but one patient, and no stent fractures were identified. CONCLUSIONS: Stenting of the popliteal artery using the Supera stent system appears to be safe and effective. The interwoven stent design may better serve areas under extreme mechanical stress. Our results with this highly diseased patient population justify a prospective trial in this subject.

Arterial-renal Syndrome in Patients with ESRD, a New Disease Paradigm.

BACKGROUND: Patients with end-stage renal disease (ESRD) often present with an increased risk of cardiovascular disease. Conditions of compromised cardiovascular health such as atrial fibrillation (AFIB) and peripheral arterial disease (PAD) may alter biomarker levels in a way that reflects worsening ESRD. This study profiled biomarkers and laboratory parameters of endothelium dysfunction in patients with ESRD, categorized by additional AFIB and PAD conditions. METHODS: Citrated blood samples were collected from 95 patients with ESRD. Biomarker levels were measured from plasma samples using sandwich ELISAs, including tissue plasminogen activator (tPA), D-dimer, and nitrotyrosine. Lab parameters, including BUN, calcium, creatinine, parathyroid hormone, phosphate, alkaline phosphatase, ferritin, transferrin, and total iron capacity, and patient comorbidities were obtained from patient medical records. The comorbidities were determined through provider notes, and evidence of applicable testing. RESULTS: 14.89% of patients were found to have atrial fibrillation (n = 14), 30.85% of patients were found to have peripheral arterial disease (n = 29), and 6.38% of patients were found to have both peripheral arterial disease and atrial fibrillation (n = 6). When compared to patients with only ESRD, patients with ESRD and PAD showed elevated levels of D-Dimer (p = .0314) and nitrotyrosine (p = .0330). When compared to patients with only ESRD, patients with atrial fibrillation showed elevated levels of D-Dimer (p = .0372), nitrotyrosine (p = .0322), and tPA (p = .0198). CONCLUSION: When compared to patients with just ESRD, patients with concomitant PAD had elevated levels of Nitrotyrosine and D-dimer; while patients with concomitant Afib had elevated levels of nitrotyrosine, D-dimer, as well as tPA.

Study of ultrasound thrombolysis using acoustic bubbles in a microfluidic device.

Thrombosis is a common medical entity associated with many forms of cardiovascular disease including myocardial infarction and stroke. Recently, ultrasound thrombolysis has emerged as a promising technique for thrombosis treatment by delivering acoustic waves onto blood clots. In this study, an ultrasound thrombolysis method is presented using an acoustic bubble-based microfluidic device. With acoustic actuation, microstreaming flow is created in the microchannel by oscillating bubbles, breaking up the blood clots in blood samples in a few milliseconds. In a low-frequency field, the effects of bubble size on microstreaming patterns and thrombolysis have been experimentally studied. Using image processing techniques, we have quantitatively investigated the relationship between the input signal and the thrombolysis performance. Additionally, the viability test proved that there are no significant detrimental effects on the blood cells after acoustic actuation. This acoustic bubble-based microfluidic device is demonstrated to be a promising platform for quantitative analysis of ultrasound thrombolysis. It opens up possibilities for future development of ultrasound thrombolysis devices for the diagnosis and treatment of heart diseases.

Stimulation of abdominal and upper thoracic muscles with surface electrodes for respiration and cough: Acute studies in adult canines.

OBJECTIVE: To optimize maximal respiratory responses with surface stimulation over abdominal and upper thorax muscles and using a 12-Channel Neuroprosthetic Platform. METHODS: Following instrumentation, six anesthetized adult canines were hyperventilated sufficiently to produce respiratory apnea. Six abdominal tests optimized electrode arrangements and stimulation parameters using bipolar sets of 4.5 cm square electrodes. Tests in the upper thorax optimized electrode locations, and forelimb moment was limited to slight-to-moderate. During combined muscle stimulation tests, the upper thoracic was followed immediately by abdominal stimulation. Finally, a model of glottal closure for cough was conducted with the goal of increased peak expiratory flow. RESULTS: Optimized stimulation of abdominal muscles included three sets of bilateral surface electrodes located 4.5 cm dorsal to the lateral line and from the 8th intercostal space to caudal to the 13th rib, 80 or 100 mA current, and 50 Hz stimulation frequency. The maximal expired volume was 343 ± 23 ml (n=3). Optimized upper thorax stimulation included a single bilateral set of electrodes located over the 2nd interspace, 60 to 80 mA, and 50 Hz. The maximal inspired volume was 304 ± 54 ml (n=4). Sequential stimulation of the two muscles increased the volume to 600 ± 152 ml (n=2), and the glottal closure maneuver increased the flow. CONCLUSIONS: Studies in an adult canine model identified optimal surface stimulation methods for upper thorax and abdominal muscles to induce sufficient volumes for ventilation and cough. Further study with this neuroprosthetic platform is warranted.