Prognostic value of post-percutaneous coronary intervention diastolic pressure ratio.

AIM: To evaluate the distribution of a generic diastolic pressure ratio (dPR) after angiographically successful percutaneous coronary intervention (PCI) and to assess its association with the 2­year incidence of target vessel failure (TVF), defined as a composite of cardiac mortality, target vessel revascularisation, target vessel myocardial infarction and stent thrombosis. METHODS: The dPR SEARCH study is a post hoc analysis of the prospective single-centre FFR-SEARCH registry, in which physiological assessment was performed after angiographically successful PCI in a total of 1000 patients, using a dedicated microcatheter. dPR was calculated offline with recently validated software in a subset of 735 patients. RESULTS: Mean post-PCI dPR was 0.95 ± 0.06. Post-PCI dPR was ≤ 0.89 in 15.2% of the patients. The cumulative incidence of TVF at 2­year follow-up was 9.4% in patients with a final post-PCI dPR ≤ 0.89 as compared to 6.1% in patients with a post-PCI dPR > 0.89 (adjusted hazard ratio [HR] for dPR ≤ 0.89: 1.53; 95% CI 0.74-3.13; p = 0.249). dPR ≤ 0.89 was associated with significantly higher cardiac mortality at 2 years; adjusted HR 2.40; 95% CI 1.01-5.68; p = 0.047. CONCLUSIONS: In a real-world setting, despite optimal angiographic PCI results, 15.2% of the patients had a final post-PCI dPR of ≤ 0.89, which was associated with a higher incidence of TVF and a significantly higher cardiac mortality rate.

Invasive imaging of the coronary atherosclerotic plaque.

Coronary atherosclerosis has a high prevalence and is known as the leading cause of death worldwide. Clinically, coronary atherosclerosis is routinely evaluated by coronary angiography, which provides a luminogram of the coronary artery and allows for recognizing lumen narrowing. However, angiography does not allow for the direct assessment of the disease process within the coronary vessel wall. Today, a number of catheter-based imaging methods can overcome this shortcoming and provide physicians with additional information on specific morphological components of atherosclerotic lesions. This article discusses the abilities of intravascular imaging techniques such as intravascular ultrasound (IVUS), IVUS-VH, iMAP, integrated backscatter-IVUS, intravascular optical coherence tomography, near-infrared spectroscopy and angioscopy, to diagnose coronary atherosclerosis and their potential to guide clinical decision making.

The diagnostic value of intracoronary optical coherence tomography.

Optical coherence tomography (OCT) is a novel light-based imaging modality for application in the coronary circulation. Compared to conventional intravascular ultrasound, OCT has a ten-fold higher image resolution. This advantage has seen OCT successfully applied in the assessment of atherosclerotic plaque, stent apposition, and tissue coverage, heralding a new era in intravascular coronary imaging. The present article discusses the diagnostic value of OCT, both in cardiovascular research as well as in potential clinical application.The unparalleled high image resolution and strong contrast between the coronary lumen and the vessel wall structure enable fast and reliable image interpretation. OCT makes it possible to visualize the presence of atherosclerotic plaque in order to characterize the structure and extent of coronary plaque and to quantify lumen dimensions, as well as the extent of lumen narrowing, in unprecedented detail. Based on optical properties, OCT is able to distinguish different tissue types, such as fibrous, lipid-rich, necrotic, or calcified tissue. Furthermore, OCT is able to cover the visualization of a variety of features of atherosclerotic plaques that have been associated with rapid lesion progression and clinical events, such as thin cap fibroatheroma, fibrous cap thickness, dense macrophage infiltration, and thrombus formation. These unique features allow the use of OCT to assess patients with acute coronary syndrome and to study the dynamic nature of coronary atherosclerosis in vivo and over time. This permits new insights into plaque progression, regression, and rupture, as well as the study of effects of therapies aimed at modulating these developments.Today's OCT technology allows high detail resolution as well as fast and safe clinical image acquisition. These unique features have established OCT as the gold standard for the assessment of coronary stents. This technique makes it possible to study stent expansion, peri-procedural vessel trauma, and the interaction of the stent with the vessel wall down to the level of individual stent struts, both acutely as well as in the long term, where it is has proven extremely sensitive to the detection of even minor amounts of tissue coverage. These qualities render OCT indispensable to addressing vexing clinical questions such as the relationship of drug-eluting stent deployment, vascular healing, the true time course of endothelial stent coverage, and late stent thrombosis. This may also better guide the optimal duration of dual anti-platelet therapy that currently remains unclear and relatively empirical.In the future, OCT might emerge, parallel to its undisputed position in research, as the tool of choice in all clinical scenarios where angiography is limited by its nature as a two-dimensional luminogram.

Seasonal variations of selected herbicides and related metabolites in water, sediment, seaweed and clams in the Sacca di Goro coastal lagoon (Northern Adriatic).

This study assesses the status of Sacca di Goro coastal lagoon (Northern Adriatic, Italy) with respect to watershed pollution. Because 80% of its watershed is devoted to agriculture, plant protection products and their metabolites were found in the water column, sediments (the upper 0-15 cm layer), macroalgae (Ulva rigida) and clams (Tapes philippinarum). Five seasonal sampling campaigns were performed from May 2004 to April 2005 and concentrations measured in five stations in the lagoon and six in the watershed. Relatively high concentrations of the s-triazine - terbuthylazine -, urea herbicides - diuron - and alachlor were detected through the year mainly at stations directly influenced by the Po di Volano inflow. The concentrations of products in use follow a clear seasonal pattern with spring peaks. This pattern is also visible in the sediments as well as in biota. Among metabolites, hydroxylated compounds prevailed, often with concentrations greater than those of the parent compounds. For the most part of the year, the concentrations in biota were close to detection limits, with concentration peaks in spring.

A 3D hydrodynamic fate and transport model for herbicides in Sacca di Goro coastal lagoon (Northern Adriatic).

Sacca di Goro is a shallow coastal microtidal lagoon with a surface area of 26 km2, and an average depth of about 1.5m. Fresh water pollutant loads from Po River branches and several drainage canals lead to anthropogenic eutrophication, frequent summer anoxia crises and chemical contamination. Such events not only affect the lagoon ecosystem but also cause serious economic losses, the lagoon being the second largest producer of clams in Italy. The present work aims at using a fate model coupled with COHERENS 3D hydrodynamic model to simulate and to explain the spatial distribution and temporal variations of s-triazines herbicides in the Sacca di Goro lagoon. The simulation results of spatial and temporal dynamic behaviour of atrazine, simazine and terbuthylazine have been compared with experimental data obtained during an annual monitoring programme.

Three-dimensional intravascular ultrasound assessment of noninjured edges of beta-irradiated coronary segments.

BACKGROUND: The "edge effect," late lumen loss at the margins of the treated segment, has become an important issue in the field of coronary brachytherapy. The aim of the present study was to assess the edge effect in noninjured margins adjacent to the irradiated segments after catheter-based intracoronary beta-irradiation. METHODS AND RESULTS: Fifty-three vessels were assessed by means of 3-dimensional intravascular ultrasound after the procedure and at 6- to 8-month follow-up. Fourteen vessels (placebo group) did not receive radiation (sham source), whereas 39 vessels were irradiated. In the irradiated group, 48 edges (5 mm in length) were identified as noninjured, whereas 18 noninjured edges were selected in the placebo group. We compared the volumetric intravascular ultrasound measurements of the noninjured edges of the irradiated vessels with the fully irradiated nonstented segments (IRS, n=27) (26-mm segments received the prescribed 100% isodose) and the noninjured edges of the vessels of the placebo patients. The lumen decreased (6 mm(3)) in the noninjured edges of the irradiated vessels at follow-up (P:=0. 001). We observed a similar increase in plaque volume in all segments: noninjured edges of the irradiated group (19.6%), noninjured edges of the placebo group (21.5%), and IRS (21.0%). The total vessel volume increased in the IRS in the 3 groups. No edge segment was subject to repeat revascularization. CONCLUSIONS: The edge effect occurs in the noninjured margins of radiation source train in both irradiated and placebo patients. Thus, low-dose radiation may not play an important role in this phenomenon, whereas nonmeasurable device injury may be considered a plausible alternative explanation.

Geographic miss: a cause of treatment failure in radio-oncology applied to intracoronary radiation therapy.

BACKGROUND: A recognized limitation of endovascular beta-radiation therapy is the development of new stenosis at the edges of the irradiated area. The combination of injury and low-dose radiation may be the precursor of this phenomenon. We translated the radio-oncological concept of "geographic miss" to define cases in which the radiation source did not fully cover the injured area. The aims of the study were to determine the incidence and causes of geographic miss and evaluate the impact of this inadequate treatment on the outcome of patients treated with intracoronary beta-radiation. METHODS AND RESULTS: We analyzed 50 consecutive patients treated with beta-radiation after percutaneous coronary intervention. The prescribed dose ranged between 12 and 20 Gy at 2 mm from the source axis. By means of quantitative coronary angiography, the irradiated segment (IRS) and both edges were studied before and after intervention and at 6-month follow-up. Edges that were injured during the procedure constituted the geographic miss edges. Twenty-two edges were injured during the intervention, mainly because of procedural complications that extended the treatment beyond the margins of the IRS. Late loss was significantly higher in geographic miss edges than in IRSs and uninjured edges (0.84+/-0.6 versus 0.15+/-0.4 and 0.09+/-0.4 mm, respectively; P<0.0001). Similarly, restenosis rate was significantly higher in the injured edges (10% within IRS, 40.9% in geographic miss edges, and 1.9% in uninjured edges; P<0.001). CONCLUSIONS: These data support the hypothesis that the combination of injury and low-dose beta-radiation induces deleterious outcome.

Residual plaque burden, delivered dose, and tissue composition predict 6-month outcome after balloon angioplasty and beta-radiation therapy.

BACKGROUND: Inhomogeneity of dose distribution and anatomic aspects of the atherosclerotic plaque may influence the outcome of irradiated lesions after balloon angioplasty (BA). We evaluated the influence of delivered dose and morphological characteristics of coronary stenoses treated with beta-radiation after BA. METHODS AND RESULTS: Eighteen consecutive patients treated according to the Beta Energy Restenosis Trial 1.5 were included in the study. The site of angioplasty was irradiated with the use of a beta-emitting (90)Sr/(90)Y source. With the side branches used as anatomic landmarks, the irradiated area was identified and volumetric assessment was performed by 3D intracoronary ultrasound imaging after treatment and at 6 months. The type of tissue, the presence of dissection, and the vessel volumes were assessed every 2 mm within the irradiated area. The minimal dose absorbed by 90% of the adventitial volume (D(v90)Adv) was calculated in each 2-mm segment. Diffuse calcified subsegments and those containing side branches were excluded. Two hundred six coronary subsegments were studied. Of those, 55 were defined as soft, 129 as hard, and 22 as normal/intimal thickening. Plaque volume showed less increase in hard segments as compared with soft and normal/intimal thickening segments (P<0.0001). D(v90)Adv was associated with plaque volume at follow-up after a polynomial equation with linear and nonlinear components (r = 0.71; P = 0.0001). The multivariate regression analysis identified the independent predictors of the plaque volume at follow-up: plaque volume after treatment, D(v90)Adv, and type of plaque. CONCLUSIONS: Residual plaque burden, delivered dose, and tiss composition play a fundamental role in the volumetric outcome at 6-month follow-up after beta-radiation therapy and BA.

Geometric vascular remodeling after balloon angioplasty and beta-radiation therapy: A three-dimensional intravascular ultrasound study.

BACKGROUND: Endovascular radiation appears to inhibit intimal thickening after overstretching balloon injury in animal models. The effect of brachytherapy on vascular remodeling is unknown. The aim of the study was to determine the evolution of coronary vessel dimensions after intracoronary irradiation after successful balloon angioplasty in humans. METHODS AND RESULTS: Twenty-one consecutive patients treated with balloon angioplasty and beta-radiation according to the Beta Energy Restenosis Trial-1.5 were included in the study. Volumetric assessment of the irradiated segment and both edges was performed after brachytherapy and at 6-month follow-up. Intravascular ultrasound images were acquired by means of ECG-triggered pullback, and 3-D reconstruction was performed by automated edge detection, allowing the calculation of lumen, plaque, and external elastic membrane (EEM) volumes. In the irradiated segments, mean EEM and plaque volumes increased significantly (451+/-128 to 490.9+/-159 mm(3) and 201.2+/-59 to 241.7+/-74 mm(3); P=0.01 and P=0.001, respectively), whereas luminal volume remained unchanged (250.8+/-91 to 249.2+/-102 mm(3); P=NS). The edges demonstrated an increase in mean plaque volume (26.8+/-12 to 32. 6+/-10 mm(3), P=0.0001) and no net change in mean EEM volume (71. 4+/-24 to 70.9+/-24 mm(3), P=NS), resulting in a decrease in mean luminal volume (44.6+/-16 to 38.3+/-16 mm(3), P=0.01). CONCLUSIONS: A different pattern of remodeling is observed in coronary segments treated with beta-radiation after successful balloon angioplasty. In the irradiated segments, the adaptive increase of EEM volume appears to be the major contributor to the luminal volume at follow-up. Conversely, both edges showed an increase in plaque volume without a net change in EEM volume.

Late coronary occlusion after intracoronary brachytherapy.

BACKGROUND: Intracoronary brachytherapy appears to be a promising technology to prevent restenosis. Presently, limited data are available regarding the late safety of this therapeutic modality. The aim of the study was to determine the incidence of late (>1 month) thrombosis after PTCA and radiotherapy. METHODS AND RESULTS: From April 1997 to March 1999, we successfully treated 108 patients with PTCA followed by intracoronary beta-radiation. Ninety-one patients have completed at least 2 months of clinical follow-up. Of these patients, 6.6% (6 patients) presented with sudden thrombotic events confirmed by angiography 2 to 15 months after intervention (2 balloon angioplasty and 4 stent). Some factors (overlapping stents, unhealed dissection) may have triggered the thrombosis process, but the timing of the event is extremely unusual. Therefore, the effect of radiation on delaying the healing process and maintaining a thrombogenic coronary surface is proposed as the most plausible mechanism to explain such late events. CONCLUSIONS: Late and sudden thrombosis after PTCA followed by intracoronary radiotherapy is a new phenomenon in interventional cardiology.

beta-Particle-emitting radioactive stent implantation. A safety and feasibility study.

BACKGROUND: This study represents the Heart Center Rotterdam's contribution to the Isostents for Restenosis Intervention Study, a nonrandomized multicenter trial evaluating the safety and feasibility of the radioactive Isostent in patients with single coronary artery disease. Restenosis after stent implantation is primarily caused by neointimal hyperplasia. In animal studies, beta-particle-emitting radioactive stents decrease neointimal hyperplasia by inhibiting smooth muscle cell proliferation. METHODS AND RESULTS: The radioisotope (32)P, a beta-particle emitter with a half-life of 14.3 days, was directly embedded into the Isostent. The calculated range of radioactivity was 0.75 to 1.5 microCi. Quantitative coronary angiography measurements were performed before and after the procedure and at 6-month follow-up. A total of 31 radioactive stents were used in 26 patients; 30 (97%) were successfully implanted, and 1 was embolized. Treated lesions were in the left anterior descending coronary artery (n=12), the right coronary artery (n=8), or the left circumflex coronary artery (n=6). Five patients received additional, nonradioactive stents. Treated lesion lengths were 13+/-4 mm, with a reference diameter of 2.93+/-0. 47 mm. Minimum lumen diameter increased from 0.87+/-0.28 mm preprocedure to 2.84+/-0.35 mm postprocedure. No in-hospital adverse cardiac events occurred. All patients received aspirin indefinitely and ticlopidine for 4 weeks. Twenty-three patients (88%) returned for 6-month angiographic follow-up; 17% of them had in-stent restenosis, and 13% had repeat revascularization. No restenosis was observed at the stent edges. Minimum lumen diameter at follow-up averaged 1.85+/-0.69 mm, which resulted in a late loss of 0.99+/-0. 59 mm and a late loss index of 0.53+/-0.35. No other major cardiac events occurred during the 6-month follow-up. CONCLUSIONS: The use of radioactive stents with an activity of 0.75 to 1.5 microCi is safe and feasible.

Positive geometric vascular remodeling is seen after catheter-based radiation followed by conventional stent implantation but not after radioactive stent implantation.

BACKGROUND: Recent reports demonstrate that intracoronary radiation affects not only neointimal formation but also vascular remodeling. Radioactive stents and catheter-based techniques deliver radiation in different ways, suggesting that different patterns of remodeling after each technique may be expected. METHODS AND RESULTS: We analyzed remodeling in 18 patients after conventional stent implantation, 16 patients after low-activity radioactive stent implantation, 16 patients after higher activity radioactive stent implantation, and, finally, 17 patients who underwent catheter-based radiation followed by conventional stent implantation. Intravascular ultrasound with 3D reconstruction was used after stent implantation and at the 6-month follow-up to assess remodeling within the stent margins and at its edges. Preprocedural characteristics were similar between groups. In-stent neointimal hyperplasia (NIH) was inhibited by high-activity radioactive stent implantation (NIH 9.0 mm(3)) and by catheter-based radiation followed by conventional stent implantation (NIH 6.9 mm(3)) compared with low-activity radioactive stent implantation (NIH 21.2 mm(3)) and conventional stent implantation (NIH 20.8 mm(3)) (P:=0.008). No difference in plaque or total vessel volume was seen behind the stent in the conventional, low-activity, or high-activity stent implantation groups. However, significant increases in plaque behind the stent (15%) and in total vessel volume (8%) were seen in the group that underwent catheter-based radiation followed by conventional stent implantation. All 4 groups demonstrated significant late lumen loss at the stent edges; however, edge restenosis was seen only in the group subjected to high-activity stent implantation and appeared to be due to an increase in plaque and, to a lesser degree, to negative remodeling. CONCLUSIONS: Distinct differences in the patterns of remodeling exist between conventional, radioactive, and catheter-based radiotherapy with stenting.

"Edge Effect" of (32)p radioactive stents is caused by the combination of chronic stent injury and radioactive dose falloff.

BACKGROUND: Radioactive stents have been reported to reduce in-stent neointimal thickening. An unexpected increase in neointimal response was observed, however, at the stent-to-artery transitions, the so-called "edge effect." To investigate the factors involved in this edge effect, we studied stents with 1 radioactive half and 1 regular nonradioactive half, thereby creating a midstent radioactive dose-falloff zone next to a nonradioactive stent-artery transition at one side and a radioactive stent-artery transition at the other side. METHODS AND RESULTS: Half-radioactive stents (n=20) and nonradioactive control stents (n=10) were implanted in the coronary arteries of Yucatan micropigs. Animals received aspirin and clopidogrel as antithrombotics. After 4 weeks, a significant midstent stenosis was observed by angiography in the half-radioactive stents. Two animals died suddenly because of coronary occlusion at this mid zone at 8 and 10 weeks. At 12-week follow-up angiography, intravascular ultrasound and histomorphometry showed a significant neointimal thickening at the midstent dose-falloff zone of the half-radioactive stents, but not at the stent-to-artery transitions at both extremities. Such a midstent response (mean angiographic late loss 1.0 mm) was not observed in the nonradioactive stents (mean loss 0.4 to 0.6 mm; P< 0.01). CONCLUSIONS: The edge effect of high-dose radioactive stents in porcine coronary arteries is associated with the combination of stent injury and radioactive dose falloff.

Preserved endothelium-dependent vasodilation in coronary segments previously treated with balloon angioplasty and intracoronary irradiation.

BACKGROUND: Abnormal endothelium-dependent coronary vasomotion has been reported after balloon angioplasty (BA), as well as after intracoronary radiation. However, the long-term effect on coronary vasomotion is not known. The aim of this study was to evaluate the long-term vasomotion of coronary segments treated with BA and brachytherapy. METHODS AND RESULTS: Patients with single de novo lesions treated either with BA followed by intracoronary beta-irradiation (according to the Beta Energy Restenosis Trial-1.5) or with BA alone were eligible. Of these groups, those patients in stable condition who returned for 6-month angiographic follow-up formed the study population (n=19, irradiated group and n=11, control group). Endothelium-dependent coronary vasomotion was assessed by selective infusion of serial doses of acetylcholine (ACh) proximally to the treated area. Mean luminal diameter was calculated by quantitative coronary angiography both in the treated area and in distal segments. Endothelial dysfunction was defined as a vasoconstriction after the maximal dose of ACh (10(-6) mol/L). Seventeen irradiated segments (89.5%) demonstrated normal endothelial function. In contrast, 10 distal nonirradiated segments (53%) and 5 control segments (45%) demonstrated endothelium-dependent vasoconstriction (-19+/-17% and -9.0+/-5%, respectively). Mean percentage of change in mean luminal diameter after ACh was significantly higher in irradiated segments (P=0.01). CONCLUSIONS: Endothelium-dependent vasomotion of coronary segments treated with BA followed by beta-radiation is restored in the majority of stable patients at 6-month follow-up. This functional response appeared to be better than those documented both in the distal segments and in segments treated with BA alone.

Usefulness of three-dimensional reconstruction for interpretation and quantitative analysis of intracoronary ultrasound during stent deployment.

We examined 49 coronary stents in 33 patients after angiographically guided optimization of the deployment by intracoronary ultrasound, and compared the findings of a conventional 2-dimensional analysis approach with the results obtained from an automatic lumen recognition provided by a 3-dimensional reconstruction system. The automatic lumen analysis demonstrated that only 15 stents (31%) fulfilled defined ultrasound criteria of adequate stent deployment, and that 5 of these cases were missed by the conventional approach, which systematically overestimated the dimensions of the minimal stent lumen.

Potentials and limitations of the Valsalva maneuver as a method of differentiating between normal and pseudonormal left ventricular filling patterns.

Pseudonormalization of the left ventricular (LV) filling pattern complicates the Doppler echocardiographic assessment of LV diastolic function in patients with heart failure. The Valsalva maneuver is recommended as a method of differentiating between normal and pseudonormal LV filling patterns. However, neither a standardized Valsalva maneuver nor a healthy control population has been studied so far. Therefore, we studied changes in mitral flow velocities in response to a standardized Valsolva maneuver in 55 heart failure patients with LV systolic dysfunction and 35 control subjects. The study subjects were instructed to elevate their intrathoracic airway pressure to 40 mm Hg for 10 seconds. Doppler mitral flow velocities were recorded at rest and during the Valsalva maneuver. All study subjects had comparable decreases in early mitral flow velocity, but mitral flow velocity at atrial contraction increased rather than decreased in patients with a restrictive LV filling pattern. This markedly abnormal response might be useful in detecting elevated filling pressures and pseudonormal filling patterns. Furthermore, in all but 2 patients and all control subjects with an E/A ratio between 1 and 2, inversion of the E/A ratio occurred. This proves that, in contrast to previous beliefs, inversion of the E/A ratio does not differentiate between normal and pseudonormal LV filling patterns.

Remodeling of atherosclerotic coronary arteries varies in relation to location and composition of plaque.

The aim of this study was to determine the contribution of morphologic characteristics and location of plaque in remodeling of atherosclerotic coronary arteries. Consecutive intravascular ultrasound studies performed in native coronary arteries before an intervention were included in the study. Total vessel, lumen and plaque + media areas were measured at target lesion, and distal and proximal references. Remodeling index was calculated as target total vessel area/proximal reference total vessel area, and categorized into 3 groups based on relative total vessel-area ratio: (1) > 1.1 (group A, adequate remodeling); (2) 0.9 to 1.1 (group B, failure of compensatory enlargement); and (3) <0.9 (group C, coronary shrinkage). Eighty-nine narrowings were assessed in 80 intravascular ultrasound studies. Thirty-eight lesions (43%) were defined as soft and 51 (57%) as hard. Soft plaques were more prevalent in group A than in groups B and C (p = 0.001). Conversely, the arc of calcium was larger in group C lesions (p = 0.005). At distal segments, group A lesions were more prevalent than those in groups B and C, whereas at proximal segments group C lesions were more prevalent (p = 0.007). Multivariate analysis identified the arc of calcium and the location of plaque at distal segments as independent predictors of compensatory enlargement (odds ratio 0.94, 95% confidence interval 0.90 to 0.99; odds ratio 4.6; 95% confidence interval 1.4 to 15.7, respectively), whereas hard plaques were an independent predictor of coronary shrinkage (odds ratio 4.6; 95% confidence interval 1.7 to 12.5). In conclusion, composition and location of plaque appeared to be major determinants of vessel remodeling during the process of atherosclerosis.

Three-dimensional intravascular ultrasonic volumetric quantification of stent recoil and neointimal formation of two new generation tubular stents.

Currently, several different designs of coronary stents are available. However, only a few of the new generation stents have been investigated in large randomized trials. Mechanical behavior of first-generation stents (Palmaz-Schatz, Gianturco-Roubin) may not be applied to the new designs. We investigated the chronic mechanical behavior (recoil) of 2 stents recently approved by the Food and Drug Administration (MULTILINK and NIR). Forty-eight patients with single-stent implantation (23 MULTILINK and 25 NIR) were assessed by means of volumetric 3-dimensional intravascular ultrasound analysis after the procedure and at 6-month follow-up. In addition, volumetric assessment of neointimal formation was performed. No significant chronic stent recoil was detected in both groups (delta MULTILINK stent volume: +5.6+/-41 mm3 [p = NS] and delta NIR stent volume + 2.1+/-26 mm3 [p = NS]). A similar degree of neointimal formation at 6 months was observed between the 2 stents (MULTILINK 46+/-31.9 mm3 vs NIR 39.9+/-27.6 mm3, p = NS). In conclusion, these 2 second-generation tubular stents did not show chronic recoil and appeared to promote similar proliferative response after implantation in human coronary arteries.

Guidance of intracoronary radiation therapy based on dose-volume histograms derived from quantitative intravascular ultrasound.

Application of ionizing radiation to prevent restenosis in atherosclerotic vessels treated by balloon angioplasty is a new treatment under investigation in interventional cardiology and radiology. There is variability in dose prescription, and both gamma- and beta-emitters are used, leading to a wide range of dose distribution over the arterial vessel wall. We present a new modality of dosimetry based on a method that three-dimensional (3-D) image reconstruction of electrocardiogram (ECG)-gated intravascular ultrasound (IVUS) images. Dose volume histograms (DVH) are used to describe the cumulative distribution of dose over two specific volumes: i) at the level of the luminal surface, defined with a thickness of 0.1 mm from the automatically detected contour of the highly echogenic blood-vessel interface, and ii) the adventitia volume is computed considering a 0.5-mm thickness from the echogenic media-adventitia interface. DVH provide a tool for reporting the actual delivered dose at the site believed to be the target: the adventitia, and to detect excessive radiation which could lead to vascular complications. Simulation of a gamma-emitter or of a radioactive source train in the center of the lumen are possible. The data obtained from the first ten patients included in the beta-irradiation trial (BERT 1.5) conducted in our institution are presented, supporting the use of DVH based on quantitative IVUS measurements for optimal dose prescription in vascular interventional radiation therapy.

Dynamic imaging of coronary stent structures: an ECG-gated three-dimensional intracoronary ultrasound study in humans.

Three-dimensional (3D) intracoronary ultrasound (ICUS) systems allow dynamic 3D reconstruction of coronary segments after stent deployment, but motion artifacts are frequently present. The use of an electrocardiographic-gated ICUS image acquisition workstation and a dedicated pullback device may overcome this problem. In the present study, we evaluated the potential of dynamic 3D reconstruction of intracoronary stents in 51 patients. Two different types of stent designs were investigated: (1) the Wallstent (mesh type; n = 36) and (2) the Cordis Coronary stent (coil type; n = 15). There was a tendency for imaging of the mesh stent type to be better than imaging of coil type stents (p = 0.06). Differences in the orientation of the stent struts (mesh:longitudinal; coil:transversal) most likely explain this difference. These in vivo observations were tested and confirmed in in vitro experiments. In conclusion, dynamic 3D ICUS reconstruction of the entire stent architecture in vivo was feasible for stents of mesh type, while stents of coil type were incompletely visualized.