Frank Werner

Serial Follow-up After Optimized Ultrasound-Guided Deployment of Palmaz-Schatz Stents In-Stent Neointimal Proliferation Without Significant Reference Segment Response

BACKGROUND The effects of ultrasound-guided high-pressure stenting on late stent and reference segment dimensions are unknown. In this study, we report about angiographic and ultrasound measurements to assess the amount and distribution of neointimal ingrowth within the stent and the changes of plaque burden and dimensions within the reference segments. METHODS AND RESULTS Sixty-eight consecutive patients with 72 lesions received single or multiple Palmaz-Schatz coronary stents with a standardized protocol for stent optimization under ultrasound guidance. The residual angiographic diameter stenosis was 3 +/- 12% (reference diameter, 3.16 +/- 0.61 mm). At follow-up 4.8 +/- 2.5 months later, angiography revealed a diameter stenosis of 27 +/- 21% with a restenosis rate of 15.3% (confidence interval: 7.8% to 25.6%). Lumen renarrowing within the stent was exclusively due to neointimal ingrowth; no stent compression was observed. The neointima covered 20 +/- 20% of the stent area and was more pronounced in the midportion of the stent. Volumetric assessment performed in 26 patients resulted in 13 +/- 14% or 65 +/- 28% of the stent volume occupied by neointimal ingrowth in patients without or with restenosis, respectively. Vessel remodeling had an impact on lumen dimensions only at reference sites but not within the stent. Plaque burden of 46 +/- 11% and 48 +/- 11% at the proximal and distal reference sites, respectively, did not show a relevant progression during the follow-up. CONCLUSIONS Serial ultrasound analyses did not show any evidence of stent compression or relevant vessel remodeling. Restenosis was solely due to neointimal ingrowth. Despite a considerable plaque burden within the reference segments, there was no relevant progression of the disease adjacent to the stent.

Impact of target lesion calcification on coronary stent expansion after rotational atherectomy

BACKGROUND Calcified lesions carry the risk of suboptimal stent expansion. The purpose of this study was to investigate the impact of target lesion calcification on intracoronary ultrasound (ICUS) guided stent expansion after rotational atherectomy. METHODS Stent expansion was assessed by ICUS in 39 patients with the aid of the proximal stent/proximal reference lumen, the minimal stent/mean reference lumen, and the minimal stent/minor reference lumen ratios as well as the symmetry index. Thirty-nine stent implantations in uncalcified lesions served for comparison. RESULTS Relative stent expansion ranged between 76.3% +/- 6.7% and 98.4% +/- 16.4%. Categorization according to an ICUS-derived arc of superficial lesion calcium of <180 degrees (average 102 +/- 74 degrees) or >180 degrees (average 248 +/- 71 degrees) revealed decreased stent symmetry in calcified lesions >180 degrees compared with the control group (P <.05). Despite a trend toward less expansion with increasing calcium load, no significant differences of the lumen area ratios between the study groups was present. CONCLUSION Rotational atherectomy before ICUS-guided stent implantation enables adequate stent expansion even in significant superficial target lesion calcification.

Reproducibility of neointima quantification with motorized intravascular ultrasound pullback in stented coronary arteries

BACKGROUND Intravascular ultrasound (IVUS) imaging has shown excellent reproducibility immediately after coronary stent implantation. However, the variability of measurements in lesions late after stent implantation, when neointima formation is present, has not been studied. Neointimal tissue is generally low echogenic and thus difficult to quantify. We therefore sought to analyze the reproducibility of morphometric measurements late after stent implantation. METHODS AND RESULTS Fifty consecutive patients were investigated 6 months after Palmaz-Schatz stent implantation (motorized catheter pullback 0.5 mm/s). Two experienced investigators independently identified the stent area, lumen area, and neointimal area at different sites within the stent. Planimetric measurements were performed with commercially available software. Correlation coefficient and mean difference for corresponding measurements were calculated for the intraobserver and interobserver comparisons. Variability for the intraobserver and interobserver comparisons was similar. Observer agreement regarding the presence of neointimal hyperplasia was as high as 71% (interobserver comparison 62%). The mean difference for neointima area was 0.06 +/- 1.5 mm(2) (-0.6 +/- 1.5 mm(2)); mean differences for lumen area were 0.02 +/- 0.19 mm(2) (0.03 +/- 0.17 mm(2)) and for stent area 0.01 +/- 0.09 mm(2) (-0.02 +/- 0.12 mm(2)) (values for interobserver comparison are given in parentheses). Correlation between measurements was high for all structures: correlation coefficients were 0.66 (0.69) for neointima, 0.94 (0.95) for lumen, and 0.95 (0. 91) for stent area. CONCLUSIONS Morphometric measurements of IVUS investigations with motorized IVUS pullback late after stent placement show good reproducibility. Intraobserver variability and interobserver variability are low. Differences for corresponding measurements were more pronounced for neointima area. Motorized catheter pullback guarantees high reliability of IVUS measurements and should be used routinely for clinical IVUS studies.

Coronary aneurysm after bailout stent implantation: Diagnosis of a false lumen with intravascular ultrasound

This case report describes the intravascular ultrasound (IVUS) evaluation of a coronary artery aneurysm, developed in a stented segment within 6 mo after bailout stenting. Analysis of the IVUS images provides in vivo insights in the vessel-remodeling process after mechanical injury. The proximal entrance of the false lumen could be clearly visualized as well as the relationship between the stent struts, neolumen, and vessel wall. The discussion is focused on the options for management of such patients.

Predictors of reduced coronary flow reserve in heart transplant recipients without angiographically significant coronary artery disease.

BACKGROUND Determination of coronary flow reserve (CFR) is increasingly used to assess the functional significance of cardiac allograft vasculopathy. Although the relation between CFR and angiographically defined vasculopathy has been studied extensively, little is known about other factors determining CFR in heart transplant recipients without significant lesions by coronary angiography. METHODS Sixty consecutive patients were studied 0.5 to 148 months after heart transplantation with intracoronary Doppler and intravascular ultrasound. An endothelium-independent CFR< or =2.5 was defined as abnormal. Stepwise logistic regression analysis was used to identify factors (demographic data of donor and recipient, lipid profile, epicardial vessel morphology by intravascular ultrasound, left ventricular hypertrophy, acute rejection episodes, and hemodynamics) potentially associated with a reduced CFR. RESULTS Only the presence of left ventricular hypertrophy (48% vs. 14%, P=0.007 and P=0.023, bivariate and multivariate analysis, respectively) and higher donor ages (41+/-12 vs. 29+/-11 years, P=0.002 and P=0.013, bivariate and multivariate analysis, respectively) showed an independent association with an abnormal flow reserve. CFR in patients with left ventricular hypertrophy was reduced due to higher baseline flow velocities (27+/-11 vs. 20+/-6 cm/sec, P=0.004). Furthermore, resting flow velocity increased as a function of donor age (r=0.264, P=0.047), while hyperemic flow velocity was not different. Other patient characteristics and hemodynamics did not affect CFR. CONCLUSION The presence of left ventricular hypertrophy and higher donor ages independently contribute to a reduced CFR in patients after heart transplantation. This reduction in CFR is due to elevated baseline flow velocities rather than to a change in hyperemic flow velocities. These findings should be taken into account for the interpretation of reduced CFR values obtained by intracoronary Doppler in heart transplant recipients without angiographically overt coronary lesions.

Coronary plaque morphologic characteristics early and late after heart transplantation: In vivo analysis with intravascular ultrasonography

To characterize plaque morphologic characteristics of transplant coronary artery disease early and late after cardiac transplantation, 72 patients were studied with intravascular ultrasonography during routine coronary angiography (group 1, 25 patients < or = 2 months after surgery; group 2, 47 patients > or = 12 months after surgery). Both groups had comparable baseline characteristics. Three hundred fifty-one segments were imaged in 127 coronary arteries (4.9 +/- 1.8 segments per patient). By intravascular ultrasonography, relevant intimal thickening (> 0.3 mm) was found in the majority of patients (68% for group 1 and 72% for group 2). Angiography detected abnormal findings in only 16% and 32% for groups 1 and 2, respectively. Mean intimal index was higher in patients late after transplantation (27% +/- 12% vs 17% +/- 12%, respectively; p < 0.01). Maximal and mean plaque thickness were comparable in both groups, whereas a higher mean plaque circumference was found in group 2 (278 +/- 66 degrees vs 211 +/- 75 degrees, respectively; p < 0.002). The lesions were more eccentric in patients early after transplantation (mean eccentricity index 95% +/- 7% vs 77% +/- 15%, respectively; p < 0.0001). Diffuse, concentric intimal thickening was not a common pattern. Maximal plaque thickness correlated with donor age (r = 0.50, p < 0.0001). Coronary lesions were frequent even early after transplantation, with predominantly eccentric plaque morphologic characteristics indicative of preexisting atherosclerosis. Later after transplantation, a more homogeneous plaque distribution was seen, partly with diffuse concentic intimal thickening. Late transplant coronary artery disease appears to be a combination of preexisting native and acquired immune-mediated coronary artery disease.

IVUS analysis of the acute and long-term stent result using motorized pullback: Intraobserver and interobserver variability

Intravascular ultrasound imaging has become an established method for analysis of intra‐coronary stents. We analyzed the reproducibility of morphometric measurements immediately and late after stent implantation and the variability in the selection of predefined sites during motorized catheter pullback. Fifty consecutive patients were investigated immediately and 6 months after Palmaz‐Schatz stent implantation (motorized catheter pullback 0.5 mm/sec; 2.9 Fr; 30‐MHz transducer). Two experienced investigators independently identified the proximal and distal reference, stent inlet, stent outlet, and the minimal in‐stent area in each imaging run. The longitudinal distance between corresponding measurement sites was calculated. Lumen, stent, and vessel area were assessed by planimetry, mean difference was calculated. Long‐term reproducibility was analyzed by comparison of measurements made at predefined sites within the stent, immediately and late after implantation. Observer agreement in identification of predefined measurement sites was high. Longitudinal distance between corresponding measurement sites was low and pronounced for the minimal in‐stent lumen area. Variabilities for the intra‐ and interobserver comparison were similar. Values for interobserver comparison were given in brackets. Acute after stent implantation, the variability for the reference proximal was 4.9% (0.4%), distal −1.0% (−4.2%), minimal in‐stent lumen −0.5% (1.3%). At follow‐up, variability for the reference proximal was −11.0% (−2.2%), distal −1.0% (−2.3%), minimal in‐stent lumen 1.9% (6.1%). Long‐term reproducibility for the proximal stent inlet was 2.7% (observer 1) and −0.4% (observer 2), for the distal stent outlet 1.3% (observer 1), −3.0% (observer 2), respectively. IVUS investigations with motorized IVUS pullback in stented coronary segments show a low intra‐ and interobserver variability, both immediately and late after stent implantation. Absolute and relative area differences are low. Long‐term reproducibility of measurements within predefined stent sites was high. Motorized catheter pullback guarantees high reliability of IVUS measurements and should be routinely used for clinical IVUS studies. Cathet. Cardiovasc. Intervent. 48:245–250, 1999.

One balloon approach for optimized Palmaz-Schatz stent implantation: The MUSCAT trial

BACKGROUND After stent deployment, larger balloons are frequently needed to optimize stent expansion according to angiographic and intravascular ultrasound (IVUS) criteria. The objective of this trial was to assess the feasibility and safety of a single-balloon approach for predilation, stent implantation, and optimization with a differential-compliant balloon allowing for focal overexpansion. We also evaluated the achieved degree of stent expansion according to IVUS criteria. METHODS AND RESULTS Forty-seven consecutive patients with 50 lesions received single or multiple Palmaz-Schatz coronary stents. The final angiographic diameter stenosis was -2.6 +/- 12.6% (reference diameter, 2.89 +/- 0.44 mm), and the residual lumen area stenosis (IVUS) was 13.0 +/- 12.3% (reference area 10.8 +/- 3.0 mm2). This result was achieved in two steps (first angiographic, then IVUS-guided stent optimization). The balloon inflation pressure increased from 13.1 +/- 3.0 bar at step 1 to 16.1 +/- 3.0 bar at step 2, which resulted in a balloon to artery ratio of 0.97 +/- 0.12 and 1.10 +/- 0.15, respectively, at the low-compliant peripheral balloon segments. The more compliant central balloon segments showed a balloon to artery ratio of 1.09 +/- 0.17 and 1.28 +/- 0.17, respectively. The primary success rate for stent deployment was 94%. Acute complications included two type A and one type B dissection without clinical sequelae. CONCLUSIONS The single-balloon approach for stenting is feasible and safe. The acute result is comparable to that of other studies with IVUS-guided stent optimization, the primary success rate, however, is slightly lower with the presently available catheter.

Quantitative changes in reference segments during IVUS-guided stent implantation: Impact on the criteria for optimal stent expansion

Intravascular ultrasound is an established method to optimize stent implantation. Stent expansion is estimated from the relation between minimal in‐stent cross‐sectional area and reference lumen area. We analyzed the periprocedural lumen increment in the reference segments and its impact on intravascular ultrasound (IVUS) criteria for optimized stenting. Seventy‐five consecutive patients were studied with a 2.9 Fr, 30‐MHz system and motorized pullback (0.5 mm/sec). Lumen area was measured by planimetry; absolute and relative differences in area (Δ area) were calculated. Lumen area increment for reference segments proximal and distal to the stent was 6.4% ± 10.3% and 6.1% ± 10.8%; 49/75 patients fulfilled all IVUS criteria for optimal stent expansion at the final IVUS assessment, and 10/75 patients met all the IVUS criteria in relation to the first measurement of reference lumen area, but not in relation to the final measurement of reference lumen area. During high‐pressure dilatation within the stent, reference lumen increment is visible. If reference lumen planimetry is not repeated after additional high‐pressure balloon inflation, the final relative stent expansion may be overestimated. Cathet. Cardiovasc. Intervent. 47:434–440, 1999.

Assessment of intraindividual variability of coronary flow reserve in angiographically normal coronary arteries in transplant recipients : A study with intracoronary doppler and intravascular ultrasound

THE development of transplant coronary artery disease (TxCAD) is the major factor limiting long term survival after heart transplantation (HTx). In addition to the morphologic evaluation of TxCAD by angiography and intravascular ultrasound (IVUS), coronary flow reserve (CFR) is used as a functional parameter to assess the hemodynamic relevance of the disease. In most reports on patients after HTx, CFR was determined in a single epicardial artery and this measurement was considered representative for global graft function. The purpose of this study was to assess the intraindividual difference of the CFR values between two coronary arteries in patients after heart transplantation.