Intravascular ultrasound cross-sectional arterial imaging before and after balloon angioplasty in vitro

A prototype ultrasound imaging catheter was evaluated in vitro using 17 human atherosclerotic artery segments before and after balloon dilatation angioplasty. The catheter was 1.2 mm in diameter and incorporated a single 20-MHz ultrasound transducer to obtain cross-sectional images of the arterial lumen. In 15 of the 17 (88%) arteries, high quality images were obtained, which demonstrated clear demarcation between the lumen and the endothelium, the atheroma plaque, the muscular media, and the adventitia. Qualitative characteristics of plaque disruption, dissection, and residual flaps were readily visible. In addition, quantitative information about cross-sectional lumen area was obtained before and after balloon dilatation. The mean cross-sectional lumen area increased from 8.7 to 15.1 mm2 (p less than 0.01) following balloon dilatation. The lumen area measured from the ultrasound images following dilatation correlated closely with the area measured from histologic sections (r = 0.88). The results from this study indicate that a small-diameter ultrasound imaging catheter can be developed that will provide high-resolution qualitative and quantitative information during peripheral and coronary angioplasty.     

Efficacy of cutting balloon angioplasty for in-stent restenosis: an intravascular ultrasound evaluation

BACKGROUND: The increase in the use of stents has seen the increasing emergence of in-stent restenosis (ISR). Reports suggest that the Cutting Balloon (Interventional Technologies, San Diego, California) may be a useful treatment modality for this new clinical entity. METHODS: In this study, we compared the efficacy of Cutting Balloon angioplasty (CBA) with conventional balloon angioplasty (PTCA) for ISR in 47 patients (47 lesions). Results were evaluated with intravascular ultrasound (IVUS). The CBA group included 25 patients (mean age, 65 +/- 78 years; 7 females) and the PTCA group included 22 patients (mean age, 69 +/- 51 years; 6 females). RESULTS: The procedural success rate was 100% in both groups. IVUS showed that luminal area acute gain was larger in the CBA group (2.5 +/- 0.8 mm2) compared to the PTCA group (1.8 +/- 1.0 mm2), while late loss was smaller in the CBA group (0.5 +/- 0.4 mm2) compared to the PTCA group (1.3 +/- 0.5 mm2). The change in total area was similar in both groups. The increase in area at the stented portion was 0.4 +/- 0.8 mm2 in the CBA group and 1.2 +/- 0.5 mm2 in the PTCA group. The restenosis rate at follow-up (mean follow-up, 5.4 months) was higher in PTCA patients (59%) than in the CBA patients (24%). CONCLUSION: CBA may result in no increase in total vessel area, a constant stent area, a decrease in plaque area, and an increase in lumen area (induced by the decrease in plaque area). Our IVUS findings suggest that compared to PTCA, the dilatation mechanism of CBA may be associated with reduced dilatation of both the total vessel area and the stent area for ISR. The mechanism of this modality may minimize injury to the intimal membrane and may potentially be a primary device for in-stent restenosis in the future.     

In vitro examination of the coronary artery wall after balloon angioplasty using intracoronary ultrasound

After autopsy 12 human coronary arteries were investigated by intracoronary ultrasound in order to measure the vessel wall dimensions and to detect damage on the vessel wall architecture after balloon angioplasty. Histology revealed artherosclerosis in 11/12 arteries. A total of 41 representative coronary segments were selected for further off-line ultrasound and histological analysis. Intracoronary ultrasound and histological measurements of the vessel wall thickness after balloon dilatation demonstrated a good correlation between the maximum thickness of the intima (histology 0.62 mm vs. intracoronary ultrasound 0.65 mm, r = 0.87) and the intima-media complex (0.80 mm vs. 0.83 mm, r = 0.87), in contrast to a weak one between the minimum thickness (r = 0.46 and r = 0.37). A total of 21 cases of damage occurred during angioplasty; intracoronary ultrasound detected 17. Further analysis showed that it imaged 10 of 11 cases of damage involving more than 30° of the vessel circumference and 7 of 10 cases of damage involving less than 30° of the vessel circumference. After balloon angioplasty of diseased coronary arteries, intracoronary ultrasound is therefore reliable in measuring the maximum wall thickness and in imaging damage involving more than 30° of the vessel wall circumference.     

Impact of deep vessel wall injury and vessel stretching on subsequent arterial remodeling after balloon angioplasty: a serial intravascular ultrasound study

Background Arterial remodeling has been shown to be responsible for lumen narrowing after nonstent interventions. Methods To examine the impact of deep vessel wall injury (DI) after balloon angioplasty on the subsequent vessel remodeling process, we performed serial intravascular ultrasound (IVUS) analysis in 47 native coronary artery lesions that underwent balloon angioplasty. An IVUS study was performed before and after balloon angioplasty and repeated at follow-up. Vessel and lumen area were measured at the narrowest site before intervention. Plaque area was calculated as vessel area minus lumen area. DI was defined as the presence of plaque/vessel wall fracture deep in the medial layer (sonolucent zone by IVUS) after angioplasty. Results After angioplasty, DI was present in 18 (38%, DI group) and absent in 29 (62%, non-DI group) of lesions. During follow-up, changes in vessel area in the DI group were significantly larger than in the non-DI group (P = .007). There were no significant differences in changes in plaque area. A trend toward greater late lumen loss was observed in the non-DI group (P = .05). In the DI group, changes in lumen area correlated better with changes in vessel area (r = 0.81, P < .0001) than with changes in plaque area (r = 0.32, P = .20). However, in the non-DI group, changes in lumen area correlated with changes in plaque area (r = −0.55, P = .002), but not with changes in vessel area (r = 0.30, P = .11). Conclusions Deep vessel wall injury after balloon angioplasty is associated with the magnitude of the subsequent vessel remodeling process. The differences in the remodeling process may have implications regarding adjunctive therapies to prevent restenosis after balloon angioplasty. (Am Heart J 2002;144:323-8.)     

Impact of pre-interventional arterial remodeling on subsequent vessel behavior after balloon angioplasty: a serial intravascular ultrasound study

OBJECTIVES

The purpose of this study was to assess the impact of pre-intervention arterial remodeling on subsequent vessel behavior following balloon angioplasty.

BACKGROUND

Positive arterial remodeling before intervention has been shown to have a negative impact on the clinical outcome after nonstented coronary interventional procedures. However, the mechanism of interventions in coronary vessel geometry over time is less well characterized.

METHODS

Serial (pre-, post- and follow-up) intravascular ultrasound analysis was performed in 46 native coronary lesions. Positive remodeling (PR) was defined as vessel area (VA) at the target lesion greater than that of average reference segments. Intermediate or negative remodeling (IR/NR) was defined as VA at the target lesion less than or equal to that of average reference segment. Remodeling index was defined as VA at the target lesion site divided by that of average references.

RESULTS

Pre-interventional PR and IR/NR were present in 21 (46%) and 25 (54%) of 46 patients, respectively. At follow-up, the change in plaque area was similar between the two groups (1.3 ± 2.1 vs. 1.2 ± 2.1 mm², P = 0.840). Lesions with PR showed a significantly smaller change in VA than those with IR/NR (−0.2 ± 2.5 vs. 1.4 ± 2.3 mm², P = 0.03). As a result, late lumen loss was significantly larger in lesions whose pre-intervention configuration exhibited PR (−1.5 ± 1.8 vs. 0.2 ± 1.6 mm², P = 0.002).

CONCLUSIONS

Lesions with PR appear to have less capacity to compensate for further plaque growth after balloon angioplasty and thus show a proportional increase in late lumen loss. This may in part explain the less favorable clinical outcomes of positively remodeled lesions.     

Real-time assessment of experimental arterial angioplasty with transvenous intravascular ultrasound.

Optimal evaluation of experimental angioplasty procedures would allow real-time simultaneous assessment during the procedure without direct manipulation of treated arterial segments. To assess the feasibility and utility of transvenous real-time intravascular ultrasound imaging during experimental angioplasty, 11 consecutive atherosclerotic iliac artery segments in rabbits were imaged before, during and after thermal or conventional perfusion balloon angioplasty. A 20-MHz intravascular ultrasound catheter was positioned in the adjacent vein, and images were correlated with data from quantitative angiography and histologic studies. Images suitable for analysis were obtained at all 11 sites. Arterial distension and recoil were observed during balloon inflation and deflation. Measurements of lumen diameter and cross-sectional area by intravascular ultrasound and angiography were closely correlated (r2 = 0.90, SEE = 0.2 mm, and r2 = 0.90, SEE = 0.8 mm2, respectively). Intimal dissections were identified in six segments by intravascular ultrasound and all were concordant with histologic findings. Thus, real-time transvenous ultrasound avoids manipulation of the treated artery, and is a feasible modality for dynamic quantitative and qualitative assessment of arterial interventions.     

Mechanism of cutting balloon angioplasty for in-stent restenosis: an intravascular ultrasound study.

We investigated by intravascular ultrasound (IVUS) the mechanism of action of cutting balloon (CB) angioplasty in patients with in-stent restenosis. Seventy-one consecutive restenotic lesions of 66 patients were studied by quantitative coronary angiography (QCA) and IVUS before, immediately after, and, in 20 cases, at 24-hr time interval after CB. CB was selected according to 1:1 CB-to-stent ratio and inflated at 8 atm for 60-90 sec. Both IVUS planar and volumetric (Simpson's rule, 25 patients) analysis were carried out. IVUS measurements included external elastic membrane area (EEMA), stent area (SA), minimal lumen area (MLA), and restenosis area (RA). Following CB, QCA analysis showed increase of minimal lumen diameter (1.17 +/- 0.46 vs. 2.45 +/- 0.51 mm; P < 0.0001) and decrease of diameter stenosis (64% +/- 13% vs. 21% +/- 9%; P < 0.0001). IVUS measurements showed a significant increase of MLA (2.18 +/- 0.80 vs. 7.31 +/- 1.8 mm(2); P < 0.0001), SA (9.62 +/- 2.6 vs. 10.7 +/- 2.75 mm(2); P < 0.0001), and EEMA (17.27 +/- 5 vs. 18.1 +/- 5 mm(2); P < 0.0001) and a decrease of RA (7.43 +/- 2.63 vs. 3.45 +/- 1.39 mm(2); P < 0.0001). No significant change was observed in the original plaque + media area (7.65 +/- 3 vs. 7.38 +/- 2.9 mm(2); P = NS). Thus, of the total lumen enlargement (5.13 +/- 1.85 mm(2)), 23% was the result of increase in mean SA, whereas 77% was the result of a decrease in mean RA. These changes were associated with a 5% increase in EEMA. IVUS volumetric changes paralleled planar variations. Angiographic and IVUS changes were well maintained at 24 hr. CB enlarges coronary lumen mainly by in-stent tissue reduction associated with a moderate degree of additional stent expansion. Favorable QCA and IVUS acute results are maintained at 24 hr.     

Endothelium-dependent arterial vasoconstriction after balloon angioplasty

To determine whether balloon angioplasty can provoke arterial vasoconstriction independent of platelet aggregation and neurogenic input, we studied the spontaneous vasomotor effects of balloon dilatation in isolated, perfused whole-vessel segments of rabbit aorta and pig carotid artery. Freshly dissected rabbit thoracic aortas were mounted in a muscle bath-perfusion chamber, perfused with physiologic saline solution at 70 mm Hg, and allowed to equilibrate. The proximal or distal half of the aortas were dilated with either a "large" (5 mm, 31-51% stretch beyond relaxed diameter) or a "small" (4 mm, 5-16% stretch) balloon angioplasty catheter with the other half of the vessel serving as the control. A similar series of experiments were performed in pig carotid arteries using "large" (6 or 8 mm, 48-90% stretch) balloon catheters. The spontaneous vasomotor effects of balloon angioplasty were examined with long-axis, high-frequency ultrasonic imaging combined with computerized edge detection image processing to measure changes in segmental internal vessel diameters. Additional experiments were carried out in rabbit aortas to determine the roles of the endothelium, extracellular calcium, indomethacin, ibuprofen, and calcium-channel blockade in modulating angioplasty-induced vasoconstriction. Significant arterial vasoconstriction was observed in the balloon angioplasty segments after dilatation with 5-mm balloons but not with 4-mm balloons. After dilatation with 5-mm balloons, the angioplasty segments' cross-sectional areas decreased by an average of 31% versus 4% for the nondilated (control) segments (p less than 0.0001). Similar postangioplasty vasoconstriction was observed in the pig carotid arteries (decrease in minimal vessel cross-sectional area of 41% [angioplasty segment] versus 2% [control segment]) (p less than 0.005). This angioplasty-induced vasoconstriction was prevented by endothelial denudation before angioplasty, removal of extracellular calcium, and pretreatment with indomethacin or ibuprofen. The vasoconstriction was only partially inhibited by calcium channel blockade with verapamil. These findings demonstrate that stretch-pressure-induced arterial vasoconstriction may occur after balloon angioplasty, independent of platelet aggregation and neurogenic input. This angioplasty-induced vasoconstriction appears to be mediated by an endothelially derived cyclooxygenase product(s).     

Arterial responses to balloon coronary angioplasty: an intravascular ultrasound study.

OBJECTIVES: The purpose of this study was to examine the coronary artery response to percutaneous transluminal coronary angioplasty by using intravascular ultrasound. BACKGROUND. The immediate effects of coronary angioplasty on arterial wall geometry and surface appearance are understood poorly. Most of the available data are derived from small necropsy series, inferred from animal models or extrapolated from in vitro studies. High frequency intravascular ultrasound provides transmural images of coronary arteries in vivo. METHODS. We used intravascular ultrasound to study 29 patients before or after, or both, successful coronary angioplasty. RESULTS. The angiographic diameter narrowing was 72 +/- 13% before and improved to 19 +/- 11% after angioplasty. Calcium was visualized in 7 (24%) of the 29 angioplasty sites by fluoroscopy versus 15 (52%) of sites by intravascular ultrasound (p = 0.022). Arterial dissection after angioplasty was observed in 8 (27%) of cases by contrast angiography versus 24 (83%) by intravascular ultrasound (p less than 0.001). Intravascular ultrasound detected extensive dissection at the angioplasty site in 11 (73%) of the 15 calcified plaques and in only 3 (21%) of the 14 noncalcified plaques (p = 0.024). Arterial expansion (defined as the area within the external elastic membrane at the angioplasty site greater than that of the proximal reference segment) occurred in 29% of calcified plaques compared with 86% of noncalcified plaques (p = 0.007). CONCLUSIONS. Intravascular ultrasound is more sensitive than angiography for identifying arterial calcium and dissection at the site of angioplasty. At the site of angioplasty, arterial dissection occurred more frequently in calcified plaques whereas arterial expansion occurred more frequently in noncalcified plaques. Successful angioplasty causes a continuum of arterial responses that vary importantly with plaque composition.     

Effect of balloon angioplasty on femoral artery evaluated with intravascular ultrasound imaging.

BACKGROUND. Intravascular ultrasound was used to assess the immediate effect of balloon angioplasty on the superficial femoral artery. METHODS AND RESULTS. In 16 consecutive patients, corresponding ultrasonic cross sections (n = 72) before and after balloon angioplasty were qualitatively and quantitatively analyzed. The qualitative data were compared with angiographic findings. Before intervention, the angiographically demonstrated obstructive lesions were confirmed by intravascular ultrasound. Ultrasound enabled discrimination between soft (n = 43) and hard (n = 29) lesions, as well as between eccentric (n = 57) and concentric (n = 15) lesions. After balloon angioplasty, the presence of a dissection assessed angiographically in 14 patients was confirmed by intravascular ultrasound. Additional morphological information provided by ultrasound included plaque rupture in 14 patients and internal lamina rupture in six patients. Quantitative ultrasound data revealed an increase in free lumen area from 9.7 +/- 4.7 to 18.3 +/- 7.0 mm2 (p less than or equal to 0.01), an increase in minimal lumen diameter from 2.8 +/- 0.7 to 3.6 +/- 1.2 mm (p less than or equal to 0.01), and an increase in media-bounded area from 21.7 +/- 5.4 to 28.3 +/- 5.8 mm2 (p less than or equal to 0.01). The lesion area for the majority of cases (n = 32) remained unchanged (13.0 +/- 4.9 mm2 versus 12.9 +/- 4.6 mm2), or the lesion disappeared partially (from 9.1 +/- 0.9 to 4.3 +/- 1.4 mm2, n = 4, p less than or equal to 0.01) or totally (from 10.1 +/- 4.2 to 0 mm2, n = 6). Stretching of the arterial wall was further evidenced by medial thinning from 0.55 +/- 0.19 to 0.34 +/- 0.11 mm (p less than or equal to 0.01). CONCLUSIONS. Luminal enlargement by balloon dilatation is achieved primarily by overstretching the arterial wall, with the lesion volume remaining practically unchanged. Overstretching is accompanied almost always by dissection and plaque rupture and occasionally by an internal lamina rupture.     

Coronary arterial aneurysm formation after balloon angioplasty

The mechanism of coronary stenosis dilatation by percutaneous transluminal coronary angioplasty (PTCA) is incompletely understood. Five men who developed coronary arterial aneurysms at the site of PTCA are described. All patients were in New York Heart Association functional class III or IV at the time of PTCA. In 2 patients acute myocardial infarction was evolving and both had acute coronary occlusion. The other 3 patients had angiographic evidence of intimal disruption or acute coronary reocclusion as a result of PTCA, one of whom had undergone emergency coronary artery bypass grafting. Three patients received intracoronary streptokinase during PTCA. One patient was asymptomatic and 4 were symptomatic when the aneurysms were identified between 11 days and 4 months after PTCA. Other than the complex course and anatomy of these patients before and immediately after PTCA, no other features distinguished them from others undergoing this procedure.     

In vitro and in vivo intravascular ultrasound imaging.

This paper presents our experience with intravascular ultrasound imaging of animal and human arteries in vitro and in vivo using a high-frequency (20 M Hz) ultrasound transducer. In vitro, 32 human coronary artery segments were imaged with intravascular ultrasound and compared with corresponding histological sections. Ultrasound and histology measurements correlated significantly (P less than 0.0001) for coronary artery cross-sectional area (r = 0.94), lumen cross-sectional area (r = 0.85) and wall thickness (r = 0.92). In vivo, 19 sheep and eight human common femoral arteries were imaged and the angiographic lumen diameter of 14 animal and six human arteries was compared to the diameter of the corresponding ultrasound images. Significant correlations were found for lumen diameter in animals and humans (P less than 0.001, r = 0.91 and P less than 0.0001, r = 0.96, respectively). These studies demonstrate that this technique can provide high resolution images of arterial vessels and may have unique advantages in diagnosing atherosclerotic vascular disease and in catheter based therapies.     

Changes in unstable coronary atherosclerotic plaque composition after balloon angioplasty as determined by analysis of intravascular ultrasound radiofrequency

The effects of balloon angioplasty (BA) on plaque distribution remain incompletely documented. In 20 patients with unstable angina pectoris, intravascular ultrasound gray scale and radiofrequency analyses were performed before and after BA. Composition of the plaque was 61% fibrotic tissue, 15% fibrofatty tissue, 15% necrotic tissue, and 7% dense calcium tissue. After BA, 35% of lumen enlargement was due to an increase in total vessel area and 65% to a significant decrease in plaque area. This resulted from a longitudinal redistribution of the tissue toward the reference segments. Radiofrequency analysis showed that the fibrous and fibrofatty tissues were able to redistribute longitudinally, whereas calcium remained at the same level. A third of necrotic tissue was lost after BA. In conclusion, in unstable plaques, BA resulted in a longitudinal redistribution of fibrotic and fibrofatty tissues and disappearance of 1/3 of necrotic tissue.     

The effect of 32P beta-radiotherapy on both vessel remodeling and neointimal hyperplasia after coronary balloon angioplasty and stenting: a three-dimensional intravascular ultrasound investigation

Intracoronary radiation is a promising therapy to decrease restenosis after percutaneous intervention. The aim of this pilot study was to determine the mechanism of intracoronary beta-radiation after balloon angioplasty and stenting in a double-blind placebo-controlled randomized fashion. Twenty-six patients were randomized to either placebo (n = 6) or 3 doses (28, 35 and 42 Gy) of beta-radiation (n = 20) using the Guidant brachytherapy system (27 mm long 32P source wire). Of these, 21 patients underwent post-procedure and 6-month follow-up three-dimensional intravascular ultrasound (IVUS) assessment. Volumetric quantification was performed by means of a semi-automated contour detection system after an ECG-gated motorized pullback IVUS imaging and three-dimensional reconstruction. We compared the volumetric changes (Delta) of total vessel volume (TVV), plaque volume (PV) and lumen volume (LV) after 6 months between placebo (dummy wire) and irradiated patients. In addition, the volume of neointimal hyperplasia was quantified within the stented segments. There was an opposite behavior of TVV and LV change between placebo (DeltaTVV = -24 mm3 and DeltaLV = -42 mm3) and irradiated (DeltaTVV = +18 mm3 and (DeltaLV = +5 mm3) patients. The mean neointimal formation within the stented segment in the irradiated patients (n = 7) was 1.9 mm3 (1.5%). Our results suggest that beta-radiation affects vessel remodeling after percutaneous intervention and inhibit neointimal formation in stented patients.     

192Ir血管内照射防止兔球囊血管成形术后再狭窄

目的　旨在检验1 92 Ir血管内照射对兔球囊血管成形术后再狭窄的作用。方法　建立兔髂动脉粥样硬化模型 ,对病变血管行球囊成形术 ,同时随机分为对照组、10Gy照射组和 18Gy照射组。以导管导入1 92 Ir放射性导丝对照射组动物的扩张处进行血管内照射。 4周后处死动物 ,取出血管标本 ,进行病理组织学分析。结果　 18Gy照射组最终管腔面积较对照组及 10Gy照射组大 (P <0 0 5 ) ,18Gy照射组内膜面积较小 (P <0 0 5 )。结论　提示1 92 Ir血管内照射可防止球囊血管成形术后再狭窄 ,其效果与照射剂量相关 ,其机制涉及抑制新生内膜增殖。     

In vitro measurement accuracy of three-dimensional ultrasound

OBJECTIVES: We sought to validate distance and volume measurements in three-dimensional (3-D) ultrasound images. BACKGROUND: Even with the latest equipment, it is not known how accurate 3-D echocardiographic measurements are. METHODS: Six models were imaged in ethanol solution and two within a tissue phantom using a mechanical rotation device rotating in 1 degrees intervals and a real-time 3-D scanner. Distance and volume measurements (n = 60) were performed in two-dimensional (2-D) and 3-D images using TomTec and InViVo software. RESULTS: Distance measurements had a mean total error between 1.12% and 2.31% for Acuson (2.5 MHZ, 3 MHZ, and 4 MHZ) and Hewlett Parkard (HP) fusion frequencies h and m, HP fusion harmonic B in the axial, and between 3.5% and 4.9% in the lateral dimension. HP Harmonic A and B, Volumetrics (2.5 MHZ), and HP fusion Harmonic A exhibited significantly higher differences to reality with a mean difference between 5.1% and 8.9% in the axial and between 6.2% and 7.9% in the lateral direction. Axial 2-D measurements were not different from real dimensions except Volumetrics model 1. In the lateral axis, all imaging modalities were different from reality except the fusion harmonic modus B. Using the HP fusion frequency h and HP fusion Harmonic B-mode, volume measurements in 3-D images significantly underestimated reality, while Acuson's fundamental frequency 3.5 MHZ was not different from real volumes. CONCLUSION: Three-dimensional visualization using different ultrasound settings results in different accuracy.     

Oral matrix metalloproteinase inhibition and arterial remodeling after balloon dilation: an intravascular ultrasound study in the pig

BACKGROUND: Inhibition of matrix metalloproteinase (MMP) activity after balloon angioplasty by intraperitoneal injection of batimastat reduces late lumen loss by inhibition of constrictive remodeling. In the present study, we investigated whether the oral MMP inhibitor marimastat inhibits constrictive remodeling in favor of neutral or expansive remodeling. METHODS AND RESULTS: In 26 pigs, balloon dilation was performed in 101 peripheral arteries. Pigs were treated with marimastat or served as controls and were euthanized 42 days after intervention. Intravascular ultrasound was performed at all time points. Vessel area (VA) loss was assessed by calculating the change in VA at termination relative to after intervention. Arteries were divided in 3 categories: expansive remodeling (VA loss < -5%), neutral (-5% +5%). In the marimastat group, a significant reduction (53%) of late lumen loss was observed that was fully explained by impaired constrictive remodeling. In the marimastat group, the prevalence of constrictive remodeling was reduced (38% versus 75% in the control group) in favor of not only neutral but also expansive remodeling (21% and 42% versus 4% and 21% in the control group, respectively, P:<0.01). In contrast to the control group, acute luminal gain in the marimastat group did not correlate with late VA loss. CONCLUSIONS: Irrespective of the acute luminal gain by balloon dilation, the oral MMP inhibitor marimastat inhibited constrictive arterial remodeling in favor of both neutral and expansive remodeling.     

Intravascular ultrasound imaging before and after balloon angioplasty for pulmonary artery stenosis

Previous reports regarding intravascular ultrasound (IVUS) imaging of the pulmonary arteries in children and its application to balloon pulmonary angioplasty are limited. This study was designed to compare findings of IVUS imaging and those of angiography of the pulmonary artery before and after the balloon angioplasty procedure. Thirty patients had significant pulmonary artery stenosis and underwent balloon angioplasty. In all, of 34 branch pulmonary arteries were dilated. All patients underwent both angiography and IVUS imaging at the time of balloon angioplasty. The mean age at balloon angioplasty was 5.7 ± 4.0 yr. One echo-dense layer on IVUS was detected in 9% of the 34 stenotic vessels, and a two- or three-layered vascular wall pattern in 91%. The thickness of intima-medial layer (inner and middle layers) was greater than normal in 91% of stenotic vessels. After balloon angioplasty, intimal flaps and aneurysm were observed at 29 and 28 locations, respectively. Of these locations, the intimal flaps were detected by angiography in 44% and by IVUS in 100%; the aneurysm was detected by angiography in 61% and by IVUS in 93%. Media rupture was observed at 26 locations, and the change was detected only by IVUS. The present study suggests that intimal and medial changes in the pulmonary artery can be detected more precisely by IVUS than by angiography. Cathet. Cardiovasc. Intervent. 46:68–78, 1999. © 1999 Wiley-Liss, Inc.