1,309 research outputs found
Unraveling of restenosis: understanding the mechanism and finding a solution, implications of IVUS-3D and brachytherapy
The purpose of this thesis was twofold; firstly, to assess the pathophysiology of restenosis
following percutaneous transluminal coronary angioplasty (Part I); secondly, to explore the
potential of
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
Geographic Miss
Background—A recognized limitation of endovascular ß-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 ß-radiation.
Methods and Results—We analyzed 50 consecutive patients treated with ß-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 ß-radiation induces deleterious outcome
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
Diagnosis of an Intracoronary Thrombus With Intravascular Ultrasound
A60-year-old man was referred for coronary angiography because of exertional angina (Canadian Cardiovascular Society angina classification type II). Twelve years earlier, he had had a myocardial infarction with a venous bypass graft to the right coronary artery
Coronary flow velocity reserve after percutaneous interventions is predictive of periprocedural outcome
BACKGROUND: Because heterogeneous results have been reported, we assessed coronary flow velocity changes in individuals who underwent percutaneous transluminal coronary angioplasty (PTCA) and examined their impact on clinical outcome. METHODS AND RESULTS: As part of the Doppler Endpoints Balloon Angioplasty Trial Europe (DEBATE) II study, 379 patients underwent Doppler flow-guided angioplasty. All patients were evaluated according to their coronary flow velocity reserve (CFVR) results (> or =2.5 or < 2.5) at the end of the procedure. A CFVR < 2.5 after angioplasty was associated with an elevated baseline blood flow velocity in both the target artery and reference artery. CFVR before PTCA and CFVR in the reference artery were independent predictors of an optimal CFVR after balloon angioplasty (CFVR before PTCA: odds ratio [OR], 2.26; 95% confidence interval [CI], 1.57 to 3.24; CFVR in reference artery: OR, 1.90; 95% CI, 1.21 to 2.98; both P<0.001) and stent implantation (before PTCA: OR, 2.54; 95% CI, 1.47 to 4.36; reference artery: OR, 1.97; 95% CI, 1.07 to 3.87; both P<0.05). A low CFVR at the end of the procedure was an independent p
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
Two-year angiographic and intravascular ultrasound follow-up after implantation of sirolimus-eluting stents in human coronary arteries
BACKGROUND: The safety and efficacy of sirolimus-eluting stenting have been demonstrated, but the outcome of patients treated with this novel technology beyond the first year remains unknown. We sought to evaluate the angiographic, intravascular ultrasound (IVUS), and clinical outcomes of patients treated with sirolimus-eluting stents 2 years after implantation. METHODS AND RESULTS: This study included 30 patients treated with sirolimus-eluting Bx Velocity stenting (slow release [SR], n=15, and fast release [FR], n=15) in Sao Paulo, Brazil. Twenty-eight patients underwent 2-year angiographic and IVUS follow-up. No deaths occurred during the study period. In-stent late loss was slightly greater in the FR group (0.28+/-0.4 mm) than in the SR group (-0.09+/-0.23 mm, P=0.007). No patient had in-stent restenosis. At 2-year follow-up, only 1 patient (FR group) had a 52% diameter stenosis within the lesion segment, which required repeat revascularization. The target-vessel revascularization rate for the entire cohort was 10% (3/30) at 2 years. All other patients had < or =35% diameter stenosis. Angiographic lumen loss at the stent edges was also minimal (in-lesion late loss was 0.33+/-0.42 mm [FR] and 0.13+/-0.29 mm [SR]). In-stent neointimal hyperplasia volume, as detected by IVUS, remained minimal after 2 years (FR= 9.90+/-9 mm3 and SR=10.35+/-9.3 mm3). CONCLUSIONS: This study demonstrates the safety and efficacy of sirolimus-eluting Bx Velocity stents 2 years after implantation in humans. In-stent lumen dimensions remained essentially unchanged at 2-year follow-up in the 2 groups, although angiographic lumen loss was slightly higher in the FR group. Restenosis "catch-up" was not found in our patient population
Sirolimus-eluting stent for the treatment of in-stent restenosis: a quantitative coronary angiography and three-dimensional intravascular ultrasound study
BACKGROUND: We have previously reported the safety and effectiveness of sirolimus-eluting stents for the treatment of de novo coronary lesions. The present investigation explored the potential of this technology to treat in-stent restenosis. METHODS AND RESULTS: Twenty-five patients with in-stent restenosis were successfully treated with the implantation of 1 or 2 sirolimus-eluting Bx VELOCITY stents in Sao Paulo, Brazil. Nine patients received 2 stents (1.4 stents per lesion). Angiographic and volumetric intravascular ultrasound (IVUS) images were obtained after the procedure and at 4 and 12 months. All vessels were patent at the time of 12-month angiography. Angiographic late loss averaged 0.07+/-0.2 mm in-stent and -0.05+/-0.3 mm in-lesion at 4 months, and 0.36+/-0.46 mm in-stent and 0.16+/-0.42 mm in-lesion after 12 months. No patient had in-stent or stent margin restenosis at 4 months, and only one patient developed in-stent restenosis at 1-year follow-up. Intimal hyperplasia by 3-dimensional IVUS was 0.92+/-1.9 mm(3) at 4 months and 2.55+/-4.9 mm(3) after 1 year. Percent volume obstruction was 0.81+/-1.7% and 1.76+/-3.4% at the 4- and 12-month follow-up, respectively. There was no evidence of stent malapposition either acutely or in the follow-up IVUS images, and there were no deaths, stent thromboses, or repeat revascularizations. CONCLUSION: This study demonstrates the safety and the potential utility of sirolimus-eluting Bx VELOCITY stents for the treatment of in-stent restenosis
Lack of Neointimal Proliferation After Implantation of Sirolimus-Coated Stents in Human Coronary Arteries: A Quantitative Coronary Angiography and Three-Dimensional Intravascular Ultrasound Study
BACKGROUND: Restenosis remains an important limitation of interventional cardiology. Therefore, we aimed to determine the safety and efficacy of sirolimus (a cell-cycle inhibitor)-coated BX Velocity stents. METHODS AND RESULTS: Thirty patients with angina pectoris were electively treated with 2 different formulations of sirolimus-coated stents (slow release [SR], n=15, and fast release [FR], n=15). All stents were successfully delivered, and patients were discharged without clinical complications. Independent core laboratories analyzed angiographic and 3D volumetric intravascular ultrasound data (immediately after procedure and at 4-month follow-up). Eight-month clinical follow-up was obtained for all patients. There was minimal neointimal hyperplasia in both groups (11.0+/-3.0% in the SR group and 10.4+/-3.0% in the FR group, P:=NS) by ultrasound and quantitative coronary angiography (in-stent late loss, 0.09+/-0.3 mm [SR] and -0.02+/-0.3 mm [FR]; in-lesion late loss, 0.16+/-0.3 mm [SR] and -0.1+/-0.3 mm [FR]). No in-stent or edge restenosis (diameter stenosis >or=50%) was observed. No major clinical events (stent thrombosis, repeat revascularization, myocardial infarction, or death) had occurred by 8 months. CONCLUSIONS: The implantation of sirolimus-coated BX Velocity stents is feasible and safe and elicits minimal neointimal proliferation. Additional placebo-controlled trials are required to confirm these promising results
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