Utility and optimal dose of nicorandil for physiological assessment of the femoropopliteal artery.

BACKGROUND: Nicorandil is widely used as a vasodilator for the physiological assessment of coronary arteries because of its usefulness and safety; however, there are no data on its use in peripheral arteries. AIMS: To identify the utility of nicorandil and its appropriate dose for the physiological assessment on the femoropopliteal artery. METHODS: We retrospectively enrolled patients from three institutes in which physiological assessment was carried out with various doses of nicorandil before treatment. Twenty-four femoropopliteal artery stenotic lesions from 22 patients were included. The nicorandil doses used were 2, 4, and 6 mg. Twenty-two lesions were also assessed using 30 mg of papaverine. The pressure gradient (PG) and peripheral fractional flow reserve (pFFR) were calculated based on the mean and systolic pressure levels. We examined the correlation of each parameter with the peak systolic velocity ratio (PSVR) based on the duplex ultrasound images using Spearman's rank correlation coefficient. Systemic blood pressure was assessed for safety. RESULTS: The correlations were higher for mean pressure-based parameters than for systolic pressure-based parameters. As the nicorandil dose increased, the correlations among PG, pFFR, and PSVR also increased (mean pressure-based PG: 2 mg, r = 0.360; 4 mg, r = 0.498; 6 mg, r = 0.694, mean pressure-based pFFR: 2 mg, r = -0.479; 4 mg, r = -0.469; 6 mg, r = -0.641). The blood pressure after the administration of 6 mg of nicorandil was low, and the median systemic mean pressure was 65 mmHg. CONCLUSION: A 4 mg dose of nicorandil is effective and safe for the mean pressure-based physiological assessment of lesions in the femoropopliteal artery.

Do astigmatid teeth matter: a tribological review of cheliceral chelae in co-occuring mites from UK beehives.

The dentition of the chelal moveable digit in cohabiting astigmatids from UK beehives (i.e., Carpoglyphus lactis (Linnaeus), Glycyphagus domesticus (DeGeer), and Tyrophagus putrescentiae (Schrank)) is characterised for the first time using quantitative tribological measures within a 2D mechanical model. The trophic function of astigmatid chelae are reviewed in terms of macroscopic tools used by humans including hooking devices, pliers, shears, rasps and saws. Comparisons to oribatid claws and isopod dactyli are made. The overall pattern of the moveable digit form of T. putrescentiae is not just a uniformly shrunken/swollen version between the other two taxa at either the macro- or micro-scale. Mastication surface macro-roughness values are in the range of international Roughness Grade Numbers N5-N6. The moveable digit of C. lactis has low rugosity values compared to the glycyphagid and acarid (which are topographically more similar and match that roughness typical of some coral reef surfaces). C. lactis has the most plesiomorphic moveable digit form. The mastication surface of all three species as a chewing tool is distinctly ornamented despite the moveable digit of C. lactis looking like a bar-like beam. The latter has more opportunities to be a multifunctional tool behaviourally than the other two species. Little evidence of any differences in the 'spikiness' of any 'toothiness' is found. Some differences with laboratory cultured specimens are found in C. lactis and possibly T. putrescentiae suggesting where selection on the digit may be able to occur. The chelal surface of T. putrescentiae has been deformed morphologically during evolution the most, that of C. lactis the least. Repeated localised surface differentiation is a feature of the moveable digit in G. domesticus compared to the likely more concerted changes over certain nearby locations in T. putrescentiae. An impactful chelal teeth design is present in G. domesticus but this is more equivocal in T. putrescentiae. Pockets within the mastication surface of the glycyphagid (and to some extent for the acarid) may produce foodstuff crunch forces of the scale of the chelal tips of oribatids. The moveable digit dentition of G. domesticus is adapted to shred foodstuff (like a ripsaw) more than that of the grazing/shearing dentition of T. putrescentiae. The collecting 'picker' design of C. lactis posterior teeth matches the size of Bettsia alvei hyphae which attacks hive-stored pollen. Detritus accumulated in chelal digit gullets through a sawing action matches the smallest observed ingested material. The dentition of C. lactis should produce less friction when moving through food material than G. domesticus. C. lactis is the most hypocarnivorous and may 'skim' through fluids when feeding. Astigmatid teeth do matter. The three commensal species can avoid direct competition. Future work is proposed in detail.

Usefulness of velocity ratio in patients with moderate aortic stenosis and reduced left ventricular ejection fraction.

Background. Moderate aortic stenosis (AS) increases left ventricular afterload and results in unfavorable outcomes in patients with reduced left ventricular ejection fraction (LVEF). Velocity ratio (VR) may be appropriate for the evaluation of aortic valve (AV) hemodynamics because of the low dependence on flow. Therefore, this study investigated the usefulness of VR on the clinical outcomes of such patients. Method. Clinical data of patients with moderate AS (AV area, 0.60-0.85 cm2/m2; peak AV velocity, 2.0-4.0 m/s) and reduced LVEF (LVEF 20-50%) were analyzed during 2010-2018. VR was calculated as peak left ventricular outflow tract velocity/peak AV velocity. The primary endpoint included all-cause death, heart failure hospitalization, and AV replacement. Results. In total, 104 patients (mean age, 75.9 ± 7.0 years; 62.5% men) were included. LVEF was 39.5% ± 7.8%. The AV area was 0.72 ± 0.08 cm2/m2, peak AV velocity was 2.59 ± 0.40 m/s, and VR was 0.30 ± 0.07. The follow-up period was 1.7 (0.5-3.5) years. Kaplan-Meier estimates for the endpoint were 59.9% at 3 years. Multivariable analysis revealed that VR (hazard ratio, 0.947; 95% confidence interval, 0.905-0.990; p = .018) was significantly related to this endpoint. Patients with a VR <0.25 had significantly higher incidence rates of the endpoint than those with a VR ≥0.25 (85.6% versus 47.8% at 3 years; p < .001). Conclusions. Patients with moderate AS and reduced LVEF have unfavorable clinical outcomes, particularly those with low VR.

Inflow Hemodynamics of Intracranial Aneurysms: A Comparison of Computational Fluid Dynamics and 4D Flow Magnetic Resonance Imaging.

PURPOSE: Although the inflow hemodynamics of cerebral aneurysms are key factors in their rupture and recurrence after endovascular treatments, the most available method for inflow hemodynamics evaluation remains unestablished. We compared the efficacy of inflow hemodynamics evaluation using computational fluid dynamics (CFD) analysis and that using four-dimensional (4D) flow magnetic resonance imaging (MRI). METHODS: In 23 unruptured cerebral aneurysms, the inflow hemodynamics was evaluated using both CFD and 4D flow MRI. The evaluated parameters included visually classified inflow jet patterns, the inflow rate ratio (the ratio of the inflow rate at the aneurysmal orifice to the flow rate in the proximal parent artery), and the velocity ratio (the ratio of the inflow velocity to the velocity in the proximal parent artery). The Shapiro-Wilk test was used to assess the normality of variable data, and logarithmic transformation was performed for variables with non-normal distributions. Data analysis was performed using Pearson correlation analyses and the chi-square test. RESULTS: There was a significant correlation between inflow jet patterns evaluated by CFD and 4D flow MRI (p = 0.008). Moreover, there was a strong correlation between the inflow rate ratios evaluated by CFD and 4D flow MRI (r = 0.801; p <0.001). Furthermore, there was a moderate correlation between the velocity ratios measured by CFD and 4D flow MRI (r = 0.559; p = 0.008). CONCLUSION: Inflow hemodynamics evaluated by CFD analysis and 4D flow MRI showed good correlations in inflow jet pattern, inflow rate ratio, and velocity ratio.

Role of Doppler Ultrasound in Assessing the Severity of Peripheral Arterial Diseases of the Lower Limb.

BACKGROUND: Peripheral arterial disease is defined as a clinical disorder in which there is a stenosis or occlusion of the arteries of the limbs. The most common etiology is ischemia due to occlusive disease. The objective of this study is to assess the severity of lower-limb peripheral arterial diseases based on various Doppler parameters. METHODS: This descriptive cross-sectional study comprised 55 patients with clinical signs and symptoms of lower-limb peripheral arterial disease. Both inpatients and outpatients attending the authors' institute were taken up for the study. In this study, Doppler sonography was performed using 3-12 MHz linear array and 1-7 MHz curvilinear array transducers (SAMSUNG RS80A Ultrasound System). RESULTS: Out of 55 patients, Doppler sonography demonstrated echogenic plaques in 32 patients and corkscrew collaterals in 15 patients. Monophasic waveform with peak systolic velocity ratio of >2:1 was found in 42 patients, which is consistent with significant stenoses. CONCLUSION: Our study shows that Duplex Doppler sonography aided by color Doppler sonography can accurately locate the site and severity of stenosis/occlusion. It is safe, cost-effective, repeatable, and noninvasive.

Mismatch between stiffness in elastic and muscular arteries as a predictor of vascular calcification in dialysis patients.

BACKGROUND: Vascular calcification is one of the risk factors for arterial stiffness in patients with chronic kidney disease. We hypothesized that a mismatch between elastic and muscular arteries, represented as pulse wave velocity (PWV) ratio, could depict the extent of vascular calcification in end-stage renal disease. We also aimed to compare the predictive PWV ratio value to other factors possibly related to vascular calcification in dialysis population. METHODS: In this cross-sectional study, in 60 chronic dialysis patients without previous cerebrovascular events, cardiovascular disease and events or clinically evident peripheral artery disease (ankle-brachial index >0.9), carotid-femoral and carotid-radial PWV as well as central hemodynamic parameters were measured by applanation tonometry (SphygmoCor). The PWV ratio using carotid-femoral PWV divided by carotid-radial PWV was calculated. Each patient underwent blood tests and chest X-ray for aortic arch calcification scoring. Two experienced radiologists blinded to patient's medical data evaluated chest X-rays (Cohen's kappa coefficient 0.76) and calculated how many sectors were calcified (Ogawa et al. in Hemodial Int 13:301-306, 2009). Differently scored chest X-rays were repeatedly reviewed and a consensus was reached. RESULTS: The study population consisted of 31 (51.7%) males and 29 (48.3%) females, mean age 52.73 ± 13.76 years. Increased risk for aortic arch calcification was associated with higher PWV ratio even after adjustment for age, height, heart rate, ferritin level and C-reactive protein level (OR 2.59E+04, 95% CI 2.43E+01, 2.65E+09, p = 0.021). PWV ratio together with above-mentioned variables could predict the presence of aortic arch calcification with specificity of 93% (95% CI 78, 99%) and sensitivity of 53% (95% CI 34, 72%). CONCLUSION: The elastic and muscular arteries' stiffness mismatch was strongly associated with the extent of aortic arch calcification in this dialysis population and had better calcification predictive value compared to other demographic, hemodynamic and biochemical markers.

Integrating twisted wind profiles to Air Ventilation Assessment (AVA): The current status.

Twisted wind flows generated by the complex terrain of Hong Kong induce two types of complication to Air Ventilation Assessment (AVA), first, imposing a false boundary condition on the wind tunnel tests done for AVA and, second, creating an ambiguity in determining the approaching wind direction in calculating the probability of occurrence of winds. The latter issue is partially solved using correction methods in post-analysis of AVA but the accuracy of these methods is not yet accessed. This study employs two twisted wind profiles to test an urban area in a boundary layer wind tunnel to investigate the influence of twisted wind flows on the outcomes of AVA and to estimate the accuracy of three common correction methods: No-Shift, Threshold, and Proportional methods. The results reveal significant differences in wind speeds at the pedestrian level for twisted and conventional wind flows at locations with low building densities. The discrepancies in wind speeds are minimum at the locations where the density of buildings is high. The indicators calculated by the No-Shift method frequently deviate from those of the twisted wind flows, while the Threshold and Proportional methods routinely over-predict the indicators of AVA.

Duplex ultrasound assessment of native stenoses in the superficial femoral and popliteal arteries: a comparative study examining the influence of multisegment lesions.

PURPOSE: To evaluate duplex ultrasonography (DUS) in the assessment of femoropopliteal stenoses comparing a single native stenosis (SNS) to multisegmental native stenoses (MNS). METHODS: Among the 1284 patients treated for atherosclerotic occlusive disease involving the femoropopliteal segment between November 2002 and November 2012, 139 patients (97 men; mean age 68±8 years) with 142 SNS or 143 MNS in 79 and 60 patients, respectively, were eligible for this retrospective analysis. The peak systolic velocity ratios with proximal (PSVRprox) and distal (PSVRdist) reference for the 285 lesions were compared with their respective angiographic stenosis grade as measured by 2 independent readers using quantitative vascular analysis to ensure objectivity. Receiver operating characteristic curve analysis was used to evaluate sensitivity, specificity, and the optimal thresholds of PSV and PSVR for detection of stenoses by grade (>50%, >70%, or >80% diameter stenosis). The area under the curve (AUC) values of dependent and independent receiver operating characteristic curves were compared. RESULTS: For SNS, correlation of PSVRprox to diameter stenosis (R=0.88) was higher (p<0.001) than the correlation for MNS (R=0.78). In the SNS group, the AUC for detecting a >50% (0.99±0.01), >70% (0.98±0.01), and >80% (0.96±0.01) stenosis with PSVRprox was significantly higher than in the MNS group [AUC50% 0.93±0.02 (p=0.01), AUC70% 0.92±0.02 (p=0.02), and AUC80% 0.87±0.03 (p=0.003)]. The optimal thresholds for detecting >50%, >70%, and >80% stenoses for SNS using PSVRprox were 2.6, 3.3, and 3.9, respectively. For MNS, the optimal thresholds of PSVRprox were 2.6, 3.4, and 3.9, respectively, with respective sensitivities of 87%, 81%, and 75%; respective specificities of 93%, 90%, and 82%; negative predictive values of 45%, 64%, and 74%; and positive predictive values of 99%, 95%, and 83%. CONCLUSION: DUS is an optimal tool for quantification of SNS. However, a multisegment setting has a significant negative impact on the quantification of femoropopliteal artery stenosis.

The C-terminus of the long AKAP13 isoform (AKAP-Lbc) is critical for development of compensatory cardiac hypertrophy.

The objective of this study was to determine the role of A-Kinase Anchoring Protein (AKAP)-Lbc in the development of heart failure, by investigating AKAP-Lbc-protein kinase D1 (PKD1) signaling in vivo in cardiac hypertrophy. Using a gene-trap mouse expressing a truncated version of AKAP-Lbc (due to disruption of the endogenous AKAP-Lbc gene), that abolishes PKD1 interaction with AKAP-Lbc (AKAP-Lbc-ΔPKD), we studied two mouse models of pathological hypertrophy: i) angiotensin (AT-II) and phenylephrine (PE) infusion and ii) transverse aortic constriction (TAC)-induced pressure overload. Our results indicate that AKAP-Lbc-ΔPKD mice exhibit an accelerated progression to cardiac dysfunction in response to AT-II/PE treatment and TAC. AKAP-Lbc-ΔPKD mice display attenuated compensatory cardiac hypertrophy, increased collagen deposition and apoptosis, compared to wild-type (WT) control littermates. Mechanistically, reduced levels of PKD1 activation are observed in AKAP-Lbc-ΔPKD mice compared to WT mice, resulting in diminished phosphorylation of histone deacetylase 5 (HDAC5) and decreased hypertrophic gene expression. This is consistent with a reduced compensatory hypertrophy phenotype leading to progression of heart failure in AKAP-Lbc-ΔPKD mice. Overall, our data demonstrates a critical in vivo role for AKAP-Lbc-PKD1 signaling in the development of compensatory hypertrophy to enhance cardiac performance in response to TAC-induced pressure overload and neurohumoral stimulation by AT-II/PE treatment.

Semiquantitative classification of ductus venosus blood flow patterns.

OBJECTIVES: To identify the range of waveform abnormalities in the ductus venosus (DV) characterized by their timing in the cardiac cycle and to evaluate if they can be categorized into distinct patterns. METHODS: DV velocity ratios were calculated from peak velocities during ventricular systole (S), end-systolic ventricular relaxation (v), early diastole (D) and atrial systole (a) (S/v, S/D, v/D, S/a, v/a and D/a ratios). The ratios were converted to their Z-scores and elevation > 2 SD was assigned as abnormal. Combinations of ratio abnormalities were grouped to define distinct waveform patterns and their distribution was related to the clinical presentation. RESULTS: Five-hundred and forty-two abnormal DV waveforms fell into three principal patterns. In Pattern 1 only the a-wave-related ratios were abnormal (180, 33.2%), in Pattern 2 the v/D ratio was abnormal (143, 26.3%) and in Pattern 3 combinations of a-wave abnormalities in the presence of a normal v/D ratio were normal (94, 17.3%). CONCLUSIONS: Interpretation of venous waveform patterns is complex because the multiphasic waveforms reflect events in the cardiac cycle that may be differentially affected by clinical pathology. We sought to present a classification for the DV flow profile that characterizes abnormal flow confined to atrial systole and occurs during ventricular relaxation or during holodiastole. Further research is warranted to determine the significance of these patterns in specific fetal conditions.

Diagnostic utility of velocity ratio for paradoxical low-flow/low-gradient aortic stenosis.

BACKGROUND: Calcification score by cardiac computed tomography (CT) is required for diagnosis of paradoxical low-flow/low-gradient (PLFLG) aortic stenosis (AS). According to the guideline, velocity ratio (VR) < 0.25 by echocardiography is defined as severe AS, but utility of VR in patients with PLFLG AS remains unknown. This retrospective study was therefore conducted to investigate the utility of VR for a diagnosis of severe AS based on CT in patients with PLFLG AS. METHODS: We studied 58 patients with PLFLG AS. Severity of AS was defined as calcium score derived from cardiac CT. RESULTS: Of the 58 patients, 28 (48.3%) were diagnosed with severe AS based on CT, while 23 of them (82.1%) had VR < 0.25. It was noteworthy that receiver operating characteristic curve analysis showed that the optimal VR cutoff value for a diagnosis of severe AS was 0.25, with an area under the curve of 0.870 (P < 0.001). Sensitivity, specificity, positive predictive value, and negative predictive value of VR < 0.25 for a diagnosis of severe AS were 82.1%, 86.7%, 85.2% and 83.9%, respectively. Furthermore, patients who match the value of VR and severity of AS based on CT had higher prevalence of atrial fibrillation, higher serum brain natriuretic peptide concentration, larger left ventricular end-diastolic volume, and left ventricular stroke volume index. CONCLUSION: The measurement of VR is simple, and VR < 0.25 can be used for diagnosis of patients with PLFLG AS as severe. Our findings may thus have clinical implications for routine clinical practice.

Serum myostatin is associated with central-to-peripheral arterial stiffness gradient in healthy adolescents. The MACISTE Study.

BACKGROUND: myostatin is a protein compound structurally related to the TGF-beta protein, which plays a pivotal role in regulating muscle growth and extracellular matrix production. exerts both profibrotic and antihypertrophic effects on vascular smooth muscle cells. Aim of the study was to explore the potential association between serum myostatin levels (sMSTN) and carotid-femoral pulse-wave velocity (cf-PWV), carotid-radial pulse wave velocity (cr-PWV), and their ratio (PWVr), in a cohort of healthy adolescents. METHODS: a cohort of 128 healthy subjects (mean age 17±2 years, 59% male) was randomly selected from participants to the MACISTE (Metabolic And Cardiovascular Investigation at School, TErni) study. sMSTN was assessed utilizing an enzyme-linked immunosorbent assay. PWVs were measured in the supine position using high-fidelity applanation tonometry. RESULTS: The mean cf-PWV was 5.1±0.9 m/s, cr-PWV was 6.9±0.9 m/s, PWVr was 0.75±0.12. PWVr exhibited a linear increase across increasing quartiles of sMSTN (0.71±0.1, 0.74±0.1, 0.7±0.1, 0.77±0.1, p for trend=0.03), whereas the association between sMSTN and each single component of PWVr (cf-PWV, cr-PWV) did not attain statistical significance. Quartiles of sMSTN displayed a positive trend with serum HDL-cholesterol (p=0.01) and a negative one with LDL-cholesterol (p=0.01). In a multivariate linear model, the association between PWVr and sMSTN was independent from SBP values, age, sex, heart rate, BMI, HDL-cholesterol and HOMA Index. CONCLUSIONS: In healthy adolescents, sMSTN showed independent associations with PWVr, a measure of central-to-peripheral arterial stiffness gradient. sMSTN may exert differential effects on the structural and functional properties of the arterial wall.

Impact of morphological parameters on urban ventilation in compact cities: The case of the Tuscolano-Don Bosco district in Rome.

Air pollution and heat stress are major concerns associated with the liveability, resilience and sustainability of cities. They directly affect health and comfort and are associated with augmented morbidity and mortality and an increase in the energy demand for building ventilation, air cleaning and cooling. Nevertheless, the detrimental effects of poor air quality may partly be mitigated by increased urban ventilation. This strategy is closely related to the level of urbanization and the urban morphology. Therefore, detailed investigations on the impact of different morphologies on urban ventilation are of paramount importance. Computational Fluid Dynamics simulations have been widely used during the last decades to investigate the effects of the urban morphology on the urban ventilation. However, most of these studies focused on idealized building arrangements, while detailed investigations about the role of real urban morphologies are scarce. This study investigates the ventilation in a compact area in the city of Rome, Italy. 3D steady-state Reynolds-averaged Navier-Stokes simulations are performed to analyze the impact of Morphological Parameters (MP) on the urban ventilation. The results show a considerable worsening of urban ventilation with increasing building density with a reduction in the mean wind velocity up to 62% experienced at the pedestrian level (zp). Correlations between five MPs, e.g., plan area density, area-weighted mean building height, volume density, façade area density, and non-dimensional mean velocity at pedestrian level and at 10 m height are evaluated, and simple models are obtained using linear regression analysis. Among the selected MPs, the building façade area density shows a remarkable correlation with the non-dimensional mean velocity at zp (R2 = 0.82). Such correlations can be valuable tools for practitioners and urban designers, particularly during the first stage of planning, for highlighting areas potentially vulnerable to poor air conditions without running computationally expensive simulations.

Impact of Peak Systolic Velocity Ratio after Drug-Coated Balloon for Femoropopliteal Disease: Three-Month Serial Observation Vessel Echo Study.

AIM: No flow-limiting dissection after drug-coated balloon (DCB) treatment for femoropopliteal (FP) lesions is considered as one of the endpoints, but it has not investigated the difference between each vessel dissection. This study aimed to clarify whether there is a difference between no dissection and type C dissection without flow-limiting dissection for 3 months by peak systolic velocity ratio (PSVR) based on duplex ultrasonography. METHODS: Between February 2020 and April 2021, 44 consecutive de novo FP diseases that underwent endovascular therapy (EVT) with DCB were enrolled in this study. 65.9% of the patients had intermittent claudication, and mean lesion lengths were 194±107 mm. The chronic total occlusion was 38.6%. After DCB treatment, vessel dissection pattern was categorized by angiography. The minimum lumen area (MLA) identified by intravascular ultrasound was serially evaluated with PSVRs at 1 day, 1 month, and 3 months after EVT. RESULT: All lesions were treated with DCB without provisional stents. The vessel dissection pattern after DCB treatment showed that types D, E, and F were not observed, 9% were no dissection, 27% were type A, 32% were type B, and 32% were type C. In all cases, the PSVR values of MLA site were less than 2.6 at 3 months, and there were no significant differences between no dissection and type C dissection. CONCLUSION: Up to dissection pattern "C" is considered acceptable as one of the endpoints to determine the need for provisional stenting after DCB treatment.

Correlation of Inflow Velocity Ratio Detected by Phase Contrast Magnetic Resonance Angiography with the Bleb Color of Unruptured Intracranial Aneurysms.

BACKGROUND: Intraoperative rupture is the most fatal and catastrophic complication of surgery for unruptured intracranial aneurysms (UIAs); thus, it is extremely useful to predict reddish and thin-walled regions of the UIA before surgery. Although several studies have reported a relationship between the hemodynamic characteristics and intracranial aneurysm wall thickness, a consistent opinion is lacking. We aimed to investigate the relationship between objectively and quantitatively evaluated bleb wall color and hemodynamic characteristics using phase-contrast magnetic resonance angiography (PC-MRA). METHODS: Ten patients diagnosed with UIA who underwent surgical clipping and preoperative magnetic resonance imaging along with PC-MRA were included in this study. Bleb wall color was evaluated from an intraoperative video. Based on the Red (R), Green, and Blue values, bleb wall redness (modified R value; mR) was calculated and compared with the hemodynamic characteristics obtained from PC-MRA. RESULTS: The wall redness distribution of 18 blebs in 11 UIAs in 10 patients was analyzed. Bleb/neck inflow velocity ratio (Vb/Va: r = 0.66, P = 0.003) strongly correlated with mR, whereas bleb/neck inflow rate ratio (r = 0.58, P = 0.012) correlated moderately. Multivariate regression analysis revealed that only Vb/Va (P = 0.017) significantly correlated with mR. There was no correlation between wall shear stress and mR. CONCLUSIONS: The bleb redness of UIAs and Vb/Va, calculated using PC-MRA, showed a significantly greater correlation. Thus, it is possible to predict bleb thickness noninvasively before surgery. This will facilitate more detailed pre- and intraoperative strategies for clipping and coiling for safe surgery.

Strength-Endurance: Interaction Between Force-Velocity Condition and Power Output.

CONTEXT: Strength-endurance mainly depends on the power output, which is often expressed relative to the individual's maximal power capability (P max). However, an individual can develop the same power, but in different combinations of force and velocity (force-velocity condition). Also, at matched power output, changing the force-velocity condition results in a change of the velocity-specific relative power (P max v), associated with a change in the power reserve. So far, the effect of these changing conditions on strength-endurance remains unclear. PURPOSE: We aimed to test the effects of force-velocity condition and power output on strength-endurance. METHODS: Fourteen sportsmen performed (i) force- and power-velocity relationships evaluation in squat jumps and (ii) strength-endurance evaluations during repeated squat jump tests in 10 different force-velocity-power conditions, individualized based on the force- and power-velocity relationships. Each condition was characterized by different (i) relative power (%P max), (ii) velocity-specific relative power (%P max v), and (iii) ratio between force and velocity (R Fv). Strength-endurance was assessed by the maximum repetitions (SJ Rep), and the cumulated mechanical work (W tot) performed until exhaustion during repeated squat jump tests. Intra and inter-day reliability of SJ Rep were tested in one of the 10 conditions. The effects of %P max, %P max v, and R Fv on SJ Rep and W tot were tested via stepwise multiple linear regressions and two-way ANOVAs. RESULTS: SJ Rep exhibited almost perfect intra- and inter-day reliability (ICC=0.94 and 0.92, respectively). SJ Rep and W tot were influenced by %P max v and R Fv (R 2 = 0.975 and 0.971; RSME=0.243 and 0.234, respectively; both p < 0.001), with the effect of R Fv increasing with decreasing %P max v (interaction effect, p = 0.03). %P max was not considered as a significant predictor of strength-endurance by the multiple regressions analysis. SJ Rep and W tot were higher at lower %P max v and in low force-high velocity conditions (i.e., lower R Fv). CONCLUSION: Strength-endurance was almost fully dependent on the position of the exercise conditions relative to the individual force-velocity and power-velocity relationships (characterized by %P max v and R Fv). Thus, the standardization of the force-velocity condition and the velocity-specific relative power should not be overlooked for strength-endurance testing and training, but also when setting fatiguing protocols.

Loss of the Normal Gradient in Arterial Compliance and Outcomes of Chronic Kidney Disease Patients.

BACKGROUND: In dialysis patients, loss of the normal gradient in arterial compliance, assessed by the pulse wave velocity (PWV) ratio, predicts all-cause mortality better than does carotid-femoral PWV (CF-PWV) alone. However, the prognostic significance of the PWV ratio for outcome in chronic kidney disease (CKD) patients remains unclear. METHODS: In this longitudinal cohort study, CKD patients who visited our CKD management clinic between April 27, 2006, and March 27, 2008, were included and followed up. To assess the gradient in arterial compliance, the PWV ratio was calculated using CF-PWV divided by carotid-radial PWV. RESULTS: A total of 209 patients in CKD stages 1-4 with a median follow-up of 3.74 years were included. Patients with higher PWV ratio were relatively older (p < 0.001) and had worse renal function (p < 0.001), more hypertension (p < 0.001), diabetes mellitus (p < 0.001), and cardiovascular or cerebrovascular disease (p < 0.001). The median time to patient outcome (death, renal replacement therapy, or double increase in serum creatinine from baseline) in the group with a PWV ratio above the median (89.8 months, 95% CI 84.2-95.5) was shorter than that in the group with a PWV ratio below the median (105.3 months, 95% CI 101.3-109.3, p = 0.001). Univariate Cox regression analysis showed that both PWV ratio and CF-PWV were significantly associated with patient outcome. In multivariate Cox regression analysis, both PWV ratio and CF-PWV were associated with patient outcome. However, the HR for CF-PWV (2.177, 95% CI 1.064-4.453, p = 0.033) was slightly higher than that for PWV ratio (2.091, 95% CI 1.049-4.167, p = 0.036). There was a significant interaction effect between PWV ratio and CKD stage. It was shown that patients with advanced CKD stages and higher PWV ratios had a significantly higher risk of adverse CKD outcome (p = 0.006). CONCLUSIONS: The PWV ratio, as a measure of loss of the normal gradient in arterial compliance, was associated with CKD patient outcome. Patients with advanced CKD and a higher PWV ratio had a significantly higher risk of adverse CKD outcome.

Vector Flow Imaging Compared with Digital Subtraction Angiography for Stenosis Assessment in the Superficial Femoral Artery - A Study of Vector Concentration, Velocity Ratio and Stenosis Degree Percentage.

PURPOSE: Stenosis of the superficial femoral artery (SFA) induces complex blood flow with increased velocities. Disease assessment is performed with Doppler ultrasound and digital subtraction angiography (DSA), but Doppler ultrasound is limited by angle dependency and DSA by ionizing radiation. An alternative is the vector flow imaging method based on transverse oscillation (TO), an angle-independent vector velocity technique using ultrasound. In this study, flow complexity and velocity measured with TO were compared with DSA for the assessment of stenosis in the SFA. MATERIALS AND METHODS: The vector concentration, a measure of flow complexity, and the velocity ratio obtained from the stenosis and a disease-free adjacent vessel segment, were estimated with TO in 11 patients with a total of 16 stenoses of the SFA. TO data were compared with the corresponding stenosis degree percentage obtained with DSA. RESULTS: The correlation between the vector concentration and DSA was very strong (R=0.93; p<0.001; 95% confidence interval (CI): 0.81-0.98), while only moderate for velocity ratio and DSA (R=0.50; p<0.07; 95% CI: 0.00-0.80). The correlation coefficients that were found were significantly different (p<0.005) without overlapping CI. CONCLUSION: The study indicated that flow changes in the SFA induced by stenosis can be quantified with TO, and that stenosis grading may be improved by estimation of flow complexity instead of velocity ratio. TO is a potential diagnostic tool for the assessment of atherosclerosis and peripheral arterial disease.

An investigation of the detection capability of pulsed wave duplex Doppler of low grade stenosis using ultrasound contrast agent microbubbles - An in-vitro study.

OBJECTIVE: The objective of the study was to investigate whether clinically used ultrasonic contrast agents improved the accuracy of spectral Doppler ultrasound in the detection of low grade (<50%) renal artery stenosis. Low grade stenoses in the renal artery are notoriously difficult to reliably detect using Doppler ultrasound due to difficulties such as overlying fat and bowel gas. METHODS: A range of anatomically-realistic renal artery phantoms with varying low degrees of stenosis (0, 30 and 50%) were constructed and peak velocity data was measured from within the pre-stenotic and mid-stenotic regions in each phantom, for both unenhanced and contrast-enhanced spectral Doppler data acquisitions. The effect of a 20 mm overlying fat layer on the ultrasound beam distortion and phase aberration, and hence on the measured peak velocity data, was also investigated. RESULTS: The overlying fat layer produced a statistically significant underestimation (p < 0.01) in both the peak velocity and peak velocity ratio [Stenotic Region(Vmax)/Pre-stenotic Region(Vmax)] for the 0% and 30% stenosis models, but not the 50% model. A statistically significant increase (p < 0.01) in the peak velocity was found in the contrast-enhanced Doppler spectra; however, no significant difference was found between the unenhanced and contrast enhanced peak velocity ratio data, which suggests that the ratio metric has better diagnostic accuracy. The peak velocity ratios determined for each of the contrast-enhanced phantoms correctly predicted if the phantom had a stenosis and furthermore correctly classified the degree of stenosis. CONCLUSION: Contrast-enhanced Doppler ultrasound could significantly assist in the early detection of renal artery disease.

Atherosclerotic Lesions in the Superficial Femoral Artery (SFA) Characterized with Velocity Ratios using Vector Velocity Ultrasound.

PURPOSE: Atherosclerotic arteries are challenging to evaluate quantitatively using spectral Doppler ultrasound because of the turbulent flow conditions that occur in relation to the atherosclerotic stenoses. Vector velocity ultrasound is angle independent and provides flow information, which could potentially improve the diagnosis of arterial stenoses. The purpose of the study is to distinguish significant stenoses in the superficial femoral artery (> 50% diameter reduction) from non-significant stenoses based on velocity ratios derived from the commercially available vector velocity ultrasound technique Vector Flow Imaging (VFI). MATERIALS AND METHODS: Velocity ratios (intrastenotic blood flow velocity divided by pre- or poststenotic velocity) from a total of 16 atherosclerotic stenoses and plaques in the superficial femoral artery of 11 patients were obtained using VFI. The stenosis degree, expressed as percentage diameter reduction of the artery, was determined from digital subtraction angiography and compared to the velocity ratios. RESULTS: A velocity ratio of 2.5 was found to distinguish clinically relevant stenoses with>50% diameter reduction from clinically non-relevant stenoses with<50% diameter reduction and the difference was statistically significant. CONCLUSION: The study indicates that VFI is a potential future tool for the evaluation of arterial stenoses.