Change In Lumen Area Research Articles

Arterial Remodeling After Bioresorbable Scaffolds and Metallic Stents

BackgroundAlthough previous observational studies have documented late luminal enlargement and expansive remodeling following implantation of a bioresorbable vascular scaffold (BVS), no comparison with metallic stents has been conducted in a randomized fashion. ObjectivesThis study sought to compare vessel remodeling patterns after either Absorb BVS or Xience metallic drug-eluting stent (DES) implantation (Abbott Vascular, Santa Clara, California) and determine the independent predictors of remodeling. MethodsIn the ABSORB II randomized trial, 383 lesions (n = 359) were investigated by intravenous ultrasound both post-procedure and at 3-year follow-up. According to vessel and lumen area changes over 3 years, we categorized 9 patterns of vessel remodeling that were beyond the reproducibility of lumen and vessel area measurements. ResultsThe relative change in mean vessel area was significantly greater with the BVS compared to the DES (6.7 ± 12.6% vs. 2.9 ± 11.5%; p = 0.003); the relative change in mean lumen area was significantly different between the 2 arms (1.4 ± 19.1% vs. −1.9 ± 10.5%, respectively; p = 0.031). Multivariate analysis indicated that use of the BVS, female sex, balloon-artery ratio >1.25, expansion index ≥0.8, previous percutaneous coronary intervention, and higher level of low-density lipoprotein cholesterol were independent predictors of expansive remodeling. Furthermore, in the BVS arm, necrotic core pre-procedure was an independent determinant of expansive remodeling. ConclusionsExpansive vessel wall remodeling was more frequent and intense with the BVS than the metallic DES and could be determined by patient baseline characteristics and periprocedural factors. The clinical effect of the observed lumen and vessel remodeling must be investigated in further large clinical studies to optimize the clinical outcome of patients and lesions treated by bioresorbable scaffolds. (ABSORB II Randomized Controlled Trial; NCT01425281)

Response of tree growth and wood structure of Larix kaempferi, Kalopanax septemlobus and Betula platyphylla saplings to elevated CO2 concentration for 5 years exposure in a FACE system

Elevated CO 2 concentration affected biomass partitioning in above-ground biomass, but size and number of water-conducting cells were unchanged in Larix kaempferi, Kalopanax septemlobus and Betula platyphylla. Using a Free-Air CO2 Enrichment (FACE) system, we studied the effect of elevated CO2 on the growth, leaf gas exchange and xylem anatomy of a conifer, Larix kaempferi, and two angiospermous tree species, Kalopanax septemlobus and Betula platyphylla. Two-year-old seedlings were grown at control sites (ambient; 370 ppm) and FACE sites (elevated; 500 ppm) for 5 years. We measured the lumen area and number of water-conducting cells, as well as biomass and leaf gas exchange, and visualized the functional region of water transport using a dye injection experiment. Elevated CO2 did not induce any significant changes in growth or in leaf gas exchange or lumen area of earlywood tracheids in L. kaempferi relative to ambient CO2. In two other tree species, elevated CO2 was found to enhance tree height and total leaf area (LA), with no change in stomatal conductance. In K. septemlobus, there were no changes in lumen area or number of earlywood vessels, or in the functional region of water transport. B. platyphylla also underwent no changes in lumen area or number of vessels, although there was a yearly variation in the size of the vessels. Our results show that 5 years of CO2 exposure did not notably affect the anatomical features of water-conducting cells. This finding suggests that, under elevated CO2, trees respond to changes in water balance due to changes in LA by extending the hydraulically active area of xylem.

Measurement of brachial artery endothelial function using a standard blood pressure cuff

The integrity of endothelial function in major arteries (EFMA) is a powerful independent predictor of heart attack and stroke. Existing ultrasound-based non-invasive assessment methods are technically challenging and suitable only for laboratory settings. EFMA, like blood pressure (BP), is both acutely and chronically affected by factors such as lifestyle and medication. Consequently, laboratory-based measurements cannot fully gauge the effects of medical interventions on EFMA. EFMA and BP have, arguably, comparable (but complementary) value in the assessment of cardiovascular health. Widespread deployment of EFMA assessment is thus a desirable clinical goal. To this end, we propose a device based on modifying the measurement protocol of a standard electronic sphygmomanometer. The protocol involves inflating the cuff to sub-diastolic levels to enable recording of the pulse waveform before and after vasodilatory stimulus. The mechanical unloading of the arterial wall provided by the cuff amplifies the distension that occurs with each pulse, which is measured as a pressure variation in the cuff. We show that the height of the rising edge of each pulse is proportional to the change in lumen area between diastole and systole. This allows the effect of vasodilatory stimuli on the artery to be measured with high sensitivity. We compare the proposed cuff flow-mediated dilation (cFMD) method to ultrasound flow-mediated dilation (uFMD). We find significant correlation (r = 0.55, p =0.003, N = 27) between cFMD- and uFMD-based metrics obtained when the release of a 5 min cuff occlusion is employed to induce endothelial stimulus via reactive hyperemia. cFMD is approximately proportional to the square of uFMD, representing a typical increase in sensitivity to vasodilation of 300–600%. This study illustrates the potential for an individual to conveniently measure his/her EFMA by using a low-cost reprogrammed home sphygmomanometer.

Abstract 13969: Effect of Endothelial Shear Stress on the Serial Changes of Vein Grafts Assessed by Optical Coherence Tomography during the First Year After Coronary Artery Bypass Graft Surgery: Analysis from the CABG-PRO Study

Introduction: Saphenous vein grafts (SVGs) have high rates of both early (≤ 1 year) and late failure following coronary arterial bypass graft surgery (CABG). Hypothesis: Endothelial shear stress (ESS) is a critical determinant of the natural history of coronary atherosclerosis, but the influence on the structural changes of SVGs has not been studied. We evaluated the effect of ESS on the serial anatomic outcomes of SVGs assessed by optical coherence tomography (OCT) during the first postoperative year. Methods: We performed 3-dimensional SVG reconstruction in 8 SVGs using fusion of angiographic and OCT data 5-7 days after surgery (baseline) and at 12-month follow-up. Baseline ESS was assessed using computational fluid dynamics. The reconstructed SVGs were divided in consecutive 3-mm segments (n=181), and we assessed the association of baseline ESS with the anatomic outcomes in the corresponding segments at follow-up: change in lumen area and plaque burden, and neointimal area at follow-up. Baseline ESS was categorized according to the tertiles of the ESS frequency distribution. Results: Median baseline ESS in SVGs was 0.48 Pa [IQR: 0.37-0.61 Pa]). Baseline low ESS was associated with: (i) the largest decrease in lumen area (low ESS category: -8.72±0.95 mm2 vs. moderate ESS category: -5.67±0.95 mm2 vs. high ESS category: -3.64±0.95 mm2; p<0.001 low vs moderate and high ESS category), (ii) the largest increase in plaque burden (low ESS category: 24.3±3.4% vs. moderate ESS category: 22.6±3.4% vs. high ESS category: 20.9±3.4%; p=0.011 low vs high ESS category), and (iii) the largest neointimal area at 12 months (low ESS category: 4.02±0.45 mm2 vs. moderate ESS category: 3.65±0.45 mm2 vs. high ESS category: -3.57±0.45 mm2; p=0.020 low vs moderate ESS category, and p=0.009 low vs high ESS category). Conclusions: SVG areas with the lowest local ESS develop the largest lumen constriction, plaque burden increase and neointima formation. These findings provide important insights into the pathogenesis of early SVG failure.

AB0569 Markers of Subclinical Cardiovascular Disease in Behcet's Disease: Correlations with Demographic and Clinical Profile

BackgroundGrowing interest exists on the role of markers of subclinical cardiovascular disease as independent predictors of cardiovascular events. Among these, great emphasis has been placed on the role of vascular...

Associations of arterial distensibility between carotid arteries and abdominal aorta by MR

To investigate the correlations of arterial distensibility between carotid arteries and abdominal aorta by MR. Twenty eight asymptomatic old subjects (71.4 ± 6.7 years; 14 males) and 20 healthy young subjects (23.5 ± 1.0 years; 10 males) were imaged with electrocardiograph-triggered balanced turbo field echo sequence sequence. Arterial distensibility was calculated as the relative lumen area change against unit blood pressure change and its relationship between carotid arteries and abdominal aorta was determined. The arterial distensibility in old subjects was significantly smaller than that in young subjects for left carotid artery (19.0 ± 6.6 × 10(-3) /kpa versus 30.9 ± 6.5 × 10(-3) /kpa), right carotid artery (16.7 ± 6.1 × 10(-3) /kpa versus 28.6 ± 9.3 × 10(-3) /kpa), and abdominal aorta (14.3 ± 5.5 × 10(-3) /kpa versus 37.5 ± 8.8 × 10(-3) /kpa), respectively (all P < 0.001). In both age groups, distensibility of the abdominal aorta was strongly correlated with that of the left carotid artery (old age group: r = 0.553; P = 0.004; young age group: r = 0.487; P = 0.029) but not with that of the right carotid artery (old age group: r = 0.371; P = 0.062; young age group: r = 0.189; P = 0.424). The distensibility of abdominal aorta is much more strongly associated with that of the left carotid artery compared with that of the right carotid artery.

Feasibility of coronary artery wall thickening assessment in asymptomatic coronary artery disease using phase-sensitive dual-inversion recovery MRI at 3 T

ObjectivesThe purpose of this study was to (a) investigate the image quality of phase-sensitive dual-inversion recovery (PS-DIR) coronary wall imaging in healthy subjects and in subjects with known coronary artery disease (CAD) and to (b) investigate the utilization of PS-DIR at 3T in the assessment of coronary artery thickening in subjects with asymptomatic but variable degrees of CAD. Materials and MethodsA total of 37 subjects participated in this institutional review board-approved and HIPAA-compliant study. These included 21 subjects with known CAD as identified on multidetector computed tomography angiography (MDCT). Sixteen healthy subjects without known history of CAD were included. All subjects were scanned using free-breathing PS-DIR magnetic resonance imaging (MRI) for the assessment of coronary wall thickness at 3T. Lumen–tissue contrast-to-noise ratio (CNR), signal-to-noise ratio (SNR) and quantitative vessel parameters including lumen area and wall thickness were measured. Statistical analyses were performed. ResultsPS-DIR was successfully completed in 76% of patients and in 88% of the healthy subjects. Phase-sensitive signed-magnitude reconstruction, compared to modulus-magnitude images, significantly improved lumen–tissue CNR in healthy subjects (26.73±11.95 vs. 14.65±9.57, P<.001) and in patients (21.45±7.61 vs. 16.65±5.85, P<.001). There was no difference in image CNR and SNR between groups. In arterial segments free of plaques, coronary wall was thicker in patients in comparison to healthy subjects (1.74±0.27mm vs. 1.17±0.14mm, P<.001), without a change in lumen area (4.51±2.42mm2 vs. 5.71±3.11mm2, P=.25). ConclusionsThis is the first study to demonstrate the feasibility of successfully obtaining vessel wall images at 3T using PS-DIR in asymptomatic patients with known variable degrees of CAD as detected by MDCT. This was achieved with a fixed subject-invariant planning of blood signal nulling. With that limitation alleviated, PS-DIR coronary wall MRI is capable of detecting arterial thickening and positive arterial remodeling at 3T in asymptomatic CAD.

Airway Compliance Studied by Lumen Area Changes Alone Cannot Discriminate between Collapsibility and Elasticity

Airway Compliance Studied by Lumen Area Changes Alone Cannot Discriminate between Collapsibility and Elasticity

Reply: Airway Compliance Studied by Lumen Area Changes Alone Cannot Discriminate between Collapsibility and Elasticity

Reply: Airway Compliance Studied by Lumen Area Changes Alone Cannot Discriminate between Collapsibility and Elasticity

Local carotid stiffness and intima-media thickness assessment by a novel ultrasound-based system in essential hypertension

ObjectiveTo evaluate local carotid stiffness (CS) and intima-medial thickness (C-IMT) in hypertensive patients with different cardiovascular risk profile, using a new user-friendly ultrasound-based system, previously validated vs. RF-based echotracking device. MethodsWe investigated a population with different cardiovascular risk: 45 healthy normotensives (NT), 90 non-diabetic hypertensives (HT), and 48 patients with hypertension and type-2 diabetes (DM). Framingham risk factor score (FRS) was calculated. PWV was assessed by applanation tonometry. The relative stroke change in diameter (ΔD) and C-IMT were measured on carotid scans. Distensibility coefficient (DC) was calculated as ΔA/(A*ΔP), where A = diastolic lumen area, ΔA = stroke change in lumen area, and ΔP = carotid pulse pressure. CS (m/s) was calculated as (ρ*DC) − 1/2 (ρ = blood density). ResultsCS, C-IMT, PWV were significantly increased in HT and DM vs. NT. C-IMT and PWV were significantly higher in DM than HT. ΔD and DC were significantly lower in HT and DM vs. NT. FRS ≥10% group showed increased carotid diameter, C-IMT and CS than the FRS <10%. FRS was (p < 0.001) correlated with CS (r = 0.35); ΔD (r = −0.36), DC (r = 0.35), C-IMT (r = 0.48), PWV (r = 0.38). CS correlated (p < 0.05) with PWV in the entire population (r = 0.37), in the NT (r = 0.35), in the HT and DM (r = 0.20). PWV (r = 0.50) and CS (r = 0.33) were correlated with age. Determinants of aortic and carotid stiffness were identified by multivariate stepwise analysis. ConclusionsThe proposed B-mode ultrasound-based system is a reliable and user-friendly method that could serve to investigate the predictive value of CS for cardiovascular events in future large clinical studies.

Influence of inspiration level on bronchial lumen measurements with computed tomography

Bronchial dimensions measured in CT images generally do not take inspiration level into consideration. However, some studies showed that the bronchial membrane is distensible with airway inflation. Therefore, re-examination of the elasticity of bronchi is needed. To assess the influence of respiration on bronchial lumen area (defined as distensibility) in different segmental bronchi and to explore the correlations between distensibility and both lung function and emphysema severity. In 44 subjects with COPD related to alpha-1-antitrypsin deficiency (AATD), bronchial lumen area was measured in CT images, acquired at different inspiration levels. Measurements were done at matched locations in one apical and two basal segmental airways (RB1, RB10 and LB10). Airway distensibility was calculated as lumen area difference divided by lung volume difference. Bronchial lumen area in the lower lobes (RB10 and LB10) correlated positively with FEV(1)%predicted (p=0.027 for RB10; and p=0.037 for LB10, respectively). Lumen area is influenced by respiration (p=0.006, p=0.045, and, p=0.005 for RB1, RB10 and LB10, respectively). Airway distensibility was different between upper and lower bronchi (p<0.001), but it was not correlated with lung function. Lumen area of third generation bronchi is dependent on inspiration level and this distensibility is different between bronchi in the upper and lower lobes. Therefore, changes in lumen area over time should be studied whilst accounting for the lung volume changes, in order to estimate the progression of bronchial disease while excluding the effects of hyperinflation.

Remodeling is a more important determinant of lumen size than atheroma burden in left main coronary artery disease

Left main coronary artery (LMCA) disease influences survival; however, the predictors of LMCA changes over time are incompletely understood. Paired intravascular ultrasound (IVUS) and core laboratory analyses were performed in a standardized fashion in 207 subjects (mean +/- SD age 58 +/- 10 years, 80% men). The average follow-up duration was 18 months (range 12-24 months). The IVUS measurements were first obtained at the smallest lumen area and the largest plaque area at follow-up and the corresponding positions in the LMCA were then measured at baseline. The LMCA percentage of atheroma area at baseline was 38.2% +/- 11.8%, and 133 patients (64%) experienced an increase in percentage of atheroma area. Change in lumen area correlated positively with change in total vessel area (R = 0.85, P < .0001) and negatively with change in percentage of atheroma area (R = -0.58, P < .0001). Change in plaque area correlated well with change in total vessel area (R = 0.64, P < .0001) but only weakly with change in lumen area (r = 0.14, P = .039). Although LMCA length correlated negatively with baseline lumen area and total vessel area, it did not correlate with their changes over time. On multivariable analyses, current smoking predicted an increase in percentage of atheroma area (P = .0013) and plaque area (P = .0041). Height negatively predicted change in percentage of atheroma area (P = .001). The LMCA lumen dimensions are more tightly linked with remodeling than with atheroma progression/regression.

DIFFERENT IMPACT OF HYPERTENSION AND TYPE 2 DIABETES ON AORTIC, CAROTID AND PERIPHERAL VASCULAR STIFFNESS: PP.10.408

Objective: Type-2 diabetes and hypertension both induce early vascular aging. Aim of the study is to explore the impact of diabetes, hypertension, and their combination on aortic, carotid and peripheral stiffening. Design and Method: 114 subjects (18 normotensives-NT, 37 hypertensives-HT, 20 diabetic normotensives-DMNT, and 39 diabetic hypertensives-DMHT) were enrolled. Applanation tonometry was used to measure aortic (carotid to femoral) and peripheral (carotid to radial) pulse wave velocity (aPWV and pPWV respectively). Common carotid intima-media thickness (IMT) and diameter were obtained by B-mode ultrasound image sequences, using the real-time computerized contour-tracking system “Carotid Studio”. Common carotid stiffness (CS) was determined from stroke change in lumen area and local pulse pressure obtained by applanation tonometry. Results: pPWV was superimposable in all groups. aPWV significantly increased ranging from NT (7.2 ± 1.0m/s) to HT (8.1 ± 1.4m/s) and DMNT (8.2 ± 0.8m/s), reaching the highest value in the DMHT group (10.6 ± 1.9m/s). CS behaved similarly (NT 6.0 ± 0.7m/s, DMNT 6.5 ± 1.2m/s, HT 6.6 ± 1.2m/s, DMHT 7.3 ± 1.2m/s). The presence of hypertension carried a 6.9-fold (confidence limits 5–95%: 1.9–24.8) increased risk of having an increased (above the median value) aPWV, a 2.8-fold (1.1–7.4) increased risk of having an increased CS, and a 3.9-fold (1.4–10.6) increased risk of having an increased carotid diameter, regardless of age and diabetes, while the analysis was not significant for pPWV and IMT. The presence of diabetes carried a 9.6-fold (3.3–27.2) increased risk of having an increased aPWV and a 2.7-fold (1.1–6.6) increased risk of having an increased IMT, regardless of age and hypertension, while the analysis was not significant for pPWV, carotid diameter and stiffness. Conclusions: Both diabetes and hypertension are associated with normal pPWV and increased aPWV, and their combination induces an even greater aortic stiffness. Hypertension is characterized by vascular stiffness at both the aortic and carotid level. In contrast, diabetes is associated only with increased aPWV. The two conditions are also different for carotid remodeling characteristics, since hypertension determines dilation while diabetes wall thickening.

Variations in atherosclerosis and remodeling patterns in aorta and carotids.

BackgroundAtherosclerosis is a progressive disease that causes vascular remodeling that can be positive or negative. The evolution of arterial wall thickening and changes in lumen size under current "standard of care" in different arterial beds is unclear. The purpose of this study was to examine arterial remodeling and progression/regression of atherosclerosis in aorta and carotid arteries of individuals at risk for atherosclerosis normalized over a 1-year period.MethodsIn this study, 28 patients underwent at least 2 black-blood in vivo cardiovascular magnetic resonance (CMR) scans of aorta and carotids over a one-year period (Mean 17.8 ± 7.5 months). Clinical risk profiles for atherosclerosis and medications were documented and patients were followed by their referring physicians under current "standard of care" guidelines. Carotid and aortic wall lumen areas were matched across the time-points from cross-sectional images.ResultsThe wall area increased by 8.67%, 10.64%, and 13.24% per year (carotid artery, thoracic aorta and abdominal aorta respectively, p < 0.001). The lumen area of the abdominal aorta increased by 4.97% per year (p = 0.002), but the carotid artery and thoracic aorta lumen areas did not change significantly. The use of statin therapy did not change the rate of increase of wall area of carotid artery, thoracic and abdominal aorta, but decreased the rate of change of lumen area of carotid artery (-3.08 ± 11.34 vs. 0.19 ± 12.91 p < 0.05).ConclusionsResults of this study of multiple vascular beds indicated that different vascular locations exhibited varying progression of atherosclerosis and remodeling as monitored by CMR.

Serial Intravascular Ultrasound Analysis of Bifurcation Lesions Treated Using the Novel Self-Expanding Sideguard Side Branch Stent

We used intravascular ultrasound (IVUS) to assess the efficacy of the Cappella Sideguard stent system for treating coronary bifurcation lesions. Treatment of bifurcation lesions is associated with restenosis at the side branch (SB) ostium, presumably due to inadequate coverage or stent-vessel wall malapposition. To address these limitations, the Sideguard stent was developed. It includes a balloon-deployed, self-expanding, thin-strut, low-stress, nitinol bare metal stent with anatomic funnel-shaped flaring at the SB ostium. Of 25 patients enrolled in the Sideguard I First-In-Man study, complete serial (after intervention and 6-month follow-up) IVUS images were available in 11 patients. All patients were treated with (1) predilation of the SB, (2) Sideguard stenting in the SB, (3) Cypher stenting in the main vessel, and (4) kissing balloon inflations. The Sideguard stent area at the SB carina increased from 3.9 +/- 1.2 to 4.6 +/- 1.1 mm(2) (p = 0.04), resulting in no change in lumen area (3.9 +/- 1.3 vs 4.0 +/- 1.3 mm(2), p = 0.77) despite an intimal hyperplasia (IH) area of 0.6 +/- 0.7 mm(2). Six patients had minimal IH; the increase in stent area translated into an increase in lumen area of 0.4 +/- 0.6 mm(2); 5 patients had relatively more IH (1.3 +/- 0.4 mm(2)), but the increase in stent area of 1.3 +/- 0.3 mm(2) compensated for the IH, resulting in no lumen decrease. In contrast, the main vessel stent area at the carina did not change (5.9 +/- 1.1 vs 6.0 +/- 1.2 mm(2), p = 0.35). In conclusion, serial IVUS analyses of the self-expanding bare metal Sideguard stent indicate preserved SB ostial lumen dimensions at follow-up due to additional increases in stent area that more than compensated for IH.

A Numerical Model to Study the Interaction of Vascular Stents with Human Atherosclerotic Lesions

A methodology is proposed that identifies optimal stent devices for specific clinical criteria. It enables to predict the effect of stent designs on the mechanical environment of stenotic arteries. In particular, we present a numerical study which is based on the interaction of a vascular stent with a patient-specific, atherosclerotic human iliac lesion of type V. The stress evolution in four different tissue components during and after stenting is investigated. The geometric model of the artery is obtained through MRI, while anisotropic material models are applied to describe the behavior of tissues at finite strains. In order to model the observed fissuring and dissection of the plaque under dilation, the undeformed configuration of the arterial wall incorporates two initial tears. The 3D balloon-stent-artery interaction problem is modeled by means of a contact algorithm, which is based on a C(2)-continuous surface parametrization, hence avoiding numerical instabilities of standard facet-based techniques. In the simulations three different stent designs are studied. The performance of each stent is characterized by scalar quantities relating to stress changes in the artery, contact forces, and changes in lumen area after stenting. The study concludes by suggesting two optimal stent designs for two different clinically relevant parameters.

Peri-Stent Reference Segment Plaque Burden Is Associated With Disease Progression in Saphenous Vein Grafts (A Serial Intravascular Ultrasound Assessment)

We are aware of no studies of peri-stent disease progression or luminal compromise in saphenous vein graft (SVG) lesions. We used serial intravascular ultrasound (IVUS) to assess disease progression in peri-stent saphenous vein bypass graft reference segments. We studied 37 peri-stent SVG reference segments in 21 patients; 16 were proximal and 21 were distal to the stent. The same anatomic image slice was analyzed after the intervention and at follow-up; this site was 3.68 +/- 2.22 mm from the stent edge. Graft age was 10.1 +/- 5.4 years, and mean follow-up duration was 13 months (range 3 to 61). Overall, change in SVG area, change in lumen area, and change in plaque burden correlated with postintervention plaque burden (r = 0.448, p = 0.005; r = -0.584, p <0.001; and r = 0.507, p = 0.001, respectively). For the proximal edge, change in lumen area correlated with change in plaque area (r = -0.951, p <0.001), but not with change in SVG area (r = -0.337, p = 0.201). For the distal edge, change in lumen area correlated more strongly with change in plaque area (r = -0.982, p <0.001) than with change in SVG area (r = -0.624, p = 0.003). When peri-stent reference segments were divided into 2 groups according to postintervention plaque burden (>50% [n = 20] vs <50% [n = 17]), there was a greater decrease in lumen area (-1.12 +/- 0.81 vs -0.33 +/- 0.26 mm(2), p <0.001) and greater increases in SVG area (0.26 +/- 0.29 vs 0.09 +/- 0.09 mm(2), p = 0.027), plaque area (1.37 +/- 0.96 vs 0.42 +/- 0.30 mm(2), p <0.001), and plaque burden (8.2 +/- 5.6% vs. 2.8 +/- 1.6%, p <0.001) in segments with a plaque burden >50%. In conclusion, peri-stent reference segment SVG disease progression and lumen loss were more significant in segments with a greater postintervention plaque burden after implantation of a bare metal stent or drug-eluting stent.

SU-EE-A4-01: Development of Cardiac-Gated 3-Dimensional Ultrasound Imaging of Carotid Atherosclerosis

Purpose: To determine the time interval in the cardiac cycle for prospectively gated ultrasound imaging of the carotid artery that will reduce change in cross‐sectional lumen area to 5%. Method and Materials: Three female subjects (ages 26–46) were used for this pilot study. The ultrasound transducer was placed over the left common carotid artery in the transverse orientation. Images and electrocardiogram values were recorded by in‐house 3‐dimensional ultrasound acquisition software. The lumen of the common carotid artery was outlined by one observer using manual segmentation at 66 ms intervals and the area of each outline was calculated by in‐house software; this was repeated 3 times. Results: The mean change in lumen area was (15 ± 2)%. A change in lumen area of 5% was selected as the desired change after prospective gating. At systole, the interval of the cardiac cycle for 5% change was 0.19 ± 0.05 to 0.54 ± 0.08 for subject 1, 0.26 ± 0.06 to 0.67 ± 0.07 for subject 2, and 0.6 ± 0.4 to 1.0 ± 0.4 for subject 3. At diastole, the interval was 0.77 ± 0.05 to 1.15 ± 0.06 for subject 1, 0.77 ± 0.09 to 1.20 ± 0.08 for subject 2, and 0.6 ± 0.2 to 0.9 ± 0.2 for subject 3. For both diastolic and systolic intervals, there was no significant (p<.05) difference between the start and end of the intervals for subjects 1 and 2, but the interval for subject 3 was significantly different from both. Conclusion: We have combined ultrasound imaging and data from an ECG to measure the effect of cardiac cycle on lumen cross‐sectional area. The lumen area of the common carotid artery changed by 15% over the cardiac cycle. No consistent interval was found to reduce this area change to 5% for prospective gating.

Effect of Atherosclerotic Regression on Total Luminal Size of Coronary Arteries as Determined by Intravascular Ultrasound

We assessed vascular changes during atherosclerosis regression. Compensatory enlargement of coronary arteries accommodates plaque burden during atherosclerosis development. Lipid-lowering therapy has altered the natural history of coronary atherosclerosis, but the arterial changes that occur during disease regression need to be clarified. Intravascular ultrasound was performed at baseline and after approximately 18 months in 432 patients with coronary disease. Mean plaque, lumen, and total vessel area were computed in a 30-mm coronary segment of interest. Mean low-density lipoprotein cholesterol level was 2.4 mmol/L, and 88% of patients received statins. Overall, changes in plaque and total vessel areas were highly correlated (r = 0.82, p <0.0001). Among the 227 patients with plaque regression, the plaque area decrease was -0.58 +/- 0.54 mm(2), and changes in total vessel and lumen areas were -1.02 +/- 1.10 and -0.44 +/- 0.86 mm(2), respectively. The decrease in plaque area correlated better with the change in total vessel area (r = 0.64, p <0.0001) than with the change in lumen area (r = 0.20, p = 0.003). The relation between plaque regression and decrease in total vessel area was significantly better (p = 0.019) for patients with a >40% atheroma area (r = 0.72; p <0.0001) than for those with <or=40% (r = 0.48; p = 0.0004). In conclusion, regression of atherosclerotic plaque is generally accompanied by a decrease in total vessel size, without an increase in luminal dimensions. This reverse vascular remodeling may be responsible for the "regression paradox," whereby secondary prevention is associated with clinical benefits despite minimal improvement in coronary lumen dimensions.

Paradoxical increase in lumen size during progression of coronary atherosclerosis: Observations from the REVERSAL trial

Relative changes in lumen size during progression and regression of coronary atherosclerosis remain largely unknown. We assessed these changes using serial intravascular ultrasound (IVUS). From the baseline IVUS interrogations of the Reversal of Atherosclerosis with Aggressive Lipid Lowering (REVERSAL) trial, 210 focal coronary lesions with <50% angiographic stenosis were identified. Lesions were matched to the follow-up IVUS, performed after 18 months of treatment with atorvastatin 80 mg/day or pravastatin 40 mg/day. Changes in external elastic membrane (EEM) and lumen areas of lesions demonstrating progression and regression (i.e. increased and decreased atheroma area) were examined. In progressors ( n = 128), there was 1.34 mm 2 increase in EEM area for every 1 mm 2 increase in atheroma area ( r = 0.72, p < 0.0001). This resulted in 0.34 mm 2 increase in lumen area for every 1 mm 2 increase in atheroma area ( r = 0.25, p = 0.004). In contrast, there was no significant change in lumen area with regression of disease ( n = 82, r = −0.06, p = 0.59). Progression of coronary atherosclerosis can be associated with a paradoxical increase in lumen cross-sectional area, whereas regression is not associated with any change in lumen area. Measurement of changes in lumen size may not be an accurate method to study progression and regression of atherosclerotic lesions with <50% stenosis.