Schema of Step-up IBS and Calculation of Step-up IBS.

<p>(Schema of Step-up IBS) Schema of the concepts and methods for measuring step-up IBS. (A) Coronary angiography, showing a discrete moderate stenotic lesion of the LAD with an FFR value of 0.69. (B) Longitudinal IVUS image of the lesion. The proximal IBS value was measured in a segment (proximal segment) 5 mm proximal to the site with the largest lumen proximal to a stenosis but within the target lesion. The distal IBS value was measured in a segment (distal segment) 5 mm distal to the site of the smallest lumen size within the target lesion (C and D) Manually encircled cross-sectional vessel lumens and integrated backscatter values measured in the proximal segment (C) and distal segment (D) using the IB-IVUS imaging system in the end-diastolic frame. The acoustic shadows of the guidewire were manually traced and excluded to minimize acoustic artifacts. The proximal and distal integrated backscatter values were 104.73 and 121.03, respectively. Integrated backscatter values were measured in three cross-sectional slices proximal and distal to the target lesion. The mean integrated backscatter values at the proximal and distal sites were 104.89 and 120.92, respectively, and the step-up IBS value was 16.03. LAD, left anterior descending artery; FFR, fractional flow reserve; IVUS, intravascular ultrasound; IBS, intensity of blood speckle; IB-IVUS, integrated backscatter intravascular ultrasound. </p

Patient characteristics and percent diameter stenosis by QCA analysis.

<p>Patient characteristics and percent diameter stenosis by QCA analysis.</p

IVUS parameters.

<p>IVUS parameters.</p

Correlation between FFR and step-up IBS.

<p>There was an inverse correlation between FFR and step-up IBS (<i>r</i> = −0.84; <i>R²</i> = 0.71; <i>P</i> < 0.001). FFR, fractional flow reserve; IBS, intensity of blood speckle. </p

A Novel Index Using Ankle Hemodynamic Parameters to Assess the Severity of Peripheral Arterial Disease: A Pilot Study

<div><p>In peripheral arterial disease (PAD) of the lower extremities, the presence of flow-limiting stenoses can be objectively detected by the ankle-brachial index (ABI). However, the severity of ischemic symptoms is not necessarily associated with the ABI value. Atherosclerotic plaque in lower extremity PAD induces ankle arterial stiffness and reduces ankle vascular resistance, which may decrease ankle blood flow and cause ischemic symptoms. We hypothesized that the ankle hemodynamic index (AHI), defined as the ratio of ankle arterial stiffness to ankle vascular resistance, could be used to assess the blood supply deficiency in a diseased lower limb in patients with PAD. The 85 consecutive patients with PAD who were retrospectively analyzed in this study had Rutherford grade 1 to grade 6 ischemia diagnosed as PAD and significant stenotic lesions (>50% diameter stenosis) of the lower extremity on contrast angiography. The AHI was calculated as the product of the ankle pulse pressure and the ratio of heart rate to ankle mean arterial pressure (ankle pulse pressure × heart rate/ankle mean arterial pressure). The Rutherford grade was significantly correlated with the AHI (<i>r</i> = 0.50, <i>P</i> < 0.001), but not with the ABI (<i>r</i> = 0.07, <i>P</i> = 0.52). Multiple ordinal regression analysis showed that anemia (odds ratio 0.66, <i>P</i> = 0.002) and AHI (odds ratio 1.04, <i>P</i> = 0.02) were independently associated with Rutherford grade. Our study shows that AHI, a novel parameter based on the ABI measurement, is well correlated with ischemic symptoms, and may be a useful means to assess the arterial blood supply of the lower extremities of patients with PAD.</p></div

Correlation between the Rutherford classification and ABI and AHI in patients with a totally occluded iliofemoral artery or diabetes.

<p>In the subset of patients with totally occluded iliofemoral arteries (n = 33) or those with diabetes (n = 54) the correlation between Rutherford grade and AHI (<i>r</i> = 0.39, <i>R</i>^<i>2</i> = 0.15, <i>P =</i> 0.02 and <i>r</i> = 0.32, <i>R</i>^<i>2</i> = 0.10, <i>P =</i> 0.02, respectively) but not between Rutherford grade and ABI (<i>r</i> = −0.21, <i>R</i>^<i>2</i> = 0.04, <i>P</i> = 0.23, <i>r</i> = −0.12, <i>R</i>^<i>2</i> = 0.01, <i>P</i> = 0.40) was significant. ABI, ankle-brachial index; AHI, ankle hemodynamic index.</p

Correlation between the Rutherford classification and ABI and AHI.

<p>The correlation between Rutherford grade and AHI (<i>r</i> = 0.50, <i>R</i>^<i>2</i> = 0.25, <i>P</i> < 0.001) but not between Rutherford grade and ABI (<i>r</i> = 0.07, <i>R</i>^<i>2</i> = 0.005, <i>P</i> = 0.52) was significant. ABI, ankle-brachial index; AHI, ankle hemodynamic index.</p

Multiple ordinal regression analysis of the relationships between Rutherford grade and independent variables.

<p>Multiple ordinal regression analysis of the relationships between Rutherford grade and independent variables.</p

Patient characteristics, medical therapy, and Rutherford grade.

<p>Patient characteristics, medical therapy, and Rutherford grade.</p

Univariate analyses of relationships between Rutherford grade and independent variables.

<p>Univariate analyses of relationships between Rutherford grade and independent variables.</p