血管内超声的冠状动脉腔内成形术的机制研究

目的应用血管内超声的方法研究病人经皮冠状动脉(冠脉)腔内成形术(PTCA)前后冠脉内的粥样斑块和血管壁的变化,进一步明确PTCA的机制。方法择期行PTCA的病人50例,共68支血管于球囊扩张前后行冠脉内超声(ICUS)检查。记录病变部位粥样斑块的特性,最小管腔面积,弹力内膜面积和斑块面积。结果PTCA球囊扩张前后病变部位的内弹力膜面积(IELA)分别为(6.67±1.45)mm2和(8.14±1.13)mm2,术后有明显的扩大(P＜0.05)。脂质斑块,纤维斑块,钙化斑块,混合斑块各组PTCA手术前后IELA之差(ΔIELA)分别为1.84,1.52,0.40,1.23mm2,钙化斑块球囊扩张前后内弹力膜面积无明显扩大,P＜0.05。斑块的撕裂程度及管壁变化根据Honye分类法记录A型10例,B型20例,C型16例,D型12例,E1型5例,E2型5例。68个病变中有58个（85%）病变出现不同程度的斑块撕裂。12个D型撕裂中有11个是钙化的斑块,1个是混合斑块。结论粥样斑块的撕裂和管壁的牵伸在冠脉球囊扩张术的管腔增大方面同时起关键作用,较硬的斑块如钙化的斑块球囊扩张时易出现大的夹层,而血管牵伸的程度较差,用旋磨或旋切的方法处理可能会得到更好的结果。     

Influence of plaque morphology on the mechanism of luminal enlargement after directional coronary atherectomy and balloon angioplasty.

OBJECTIVE--To relate the mechanism of luminal gain after directional atherectomy and balloon angioplasty to the morphological characteristics of the coronary lesions, assessed by intravascular ultrasound imaging. DESIGN--Intravascular ultrasound imaging was performed before and after the revascularisation procedure to assess the contribution of wall stretching and plaque reduction in luminal gain. SUBJECTS--32 patients undergoing balloon angioplasty and 29 undergoing directional coronary atherectomy. MAIN RESULTS--The main luminal area in vessels treated by balloon angioplasty increased from 1.51 (SD 0.30) to 3.91 (1.09) mm2 (P < 0.0001) with a concomitant increase in total vessel area from 11.44 (2.73) to 13.07 (2.83) mm2 (P < 0.0001). Therefore stretching of the vessel wall accounted for 68% of the luminal gain while plaque reduction accounted for the remaining 32%. This mechanism ranged from 45% in non-calcific plaques to 81% in echogenic plaques. The main luminal area in vessels treated by directional atherectomy increased from 1.49 (0.32) to 4.68 (1.73) mm2 (P < 0.0001), with a concomitant increase of total vessel area from 13.61 (4.67) to 15.2 (4.04) mm2 (P = 0.006). Thus stretching of the vessel wall accounted for 49% of the luminal area gain and plaque reduction for the remaining 51%. The presence of calcium influenced the relative contribution of these two mechanisms to the final luminal gain after directional atherectomy, since in calcific plaques stretching of the vessel wall accounted for only 9% of the luminal gain as compared to 56% in non-calcific plaques. After balloon angioplasty there was greater evidence of coronary dissections (32% v 3% after directional atherectomy, P < 0.01) and plaque fissure (60% v 0%, P < 0.01). Plaque fissure was more frequently seen in echolucent and concentric lesions, whereas dissections prevailed in echogenic and eccentric lesions. CONCLUSIONS--Intravascular ultrasound imaging may allow the assessment of acute changes in lumen and vessel wall after revascularisation procedures, and help in evaluating the potential effect of the structure and morphology of coronary lesions on the mechanism of luminal enlargement.     

Morphological effects on in-stent restenosis assessed by intravascular ultrasound imaging.

The purpose of this study was to evaluate the rupture and dissection of the vessel wall immediately after balloon dilatation by intravascular ultrasound (IVUS) imaging and to predict restenosis in patients who underwent subsequent coronary stent implantation. Stent implantation improves the long-term results of coronary angioplasty by reducing lesion elastic recoil and arterial remodeling. However, several studies have suggested that neointimal hyperplasia is the cause of instant restenosis. We recruited 60 patients in whom IVUS studies were performed immediately after successful balloon dilatation and just before stent implantation. We compared IVUS parameters with 6-month follow-up quantitative coronary angiography. This was performed in 51 lesions of 51 patients (85%). Qualitative analysis included assessment of plaque composition, plaque eccentricity, plaque fracture and the presence of dissection. In addition, minimal luminal diameter, percent diameter stenosis, percent area stenosis and plaque burden were quantitatively analyzed. Two morphological patterns after balloon dilatation were classified by IVUS. Type I was defined as absence or partial tear of the plaque without disclosure of the media to lumen (22 lesions). Type II was defined as a split in the plaque or dissection of the vessel wall with disclosure of the media to the lumen (29 lesions). At 6 months follow-up, angiographic restenosis occurred in 17 of the 51 lesions (33%). Restenosis was significantly (p < 0.05) more likely to occur in type II (13/29: 45% incidence) than in type I (4/22: 18% incidence). The assessment of plaque morphology immediately after balloon dilatation and before stent implantation provides important therapeutic and prognostic implications.     

Impact of deep vessel wall injury on acute response and remodeling of coronary artery segments after cutting balloon angioplasty

Deep vessel wall injury is believed to affect vessel dimension following coronary intervention. The cutting balloon is designed to treat coronary artery stenoses with dilatation and surgical incisions, thereby reducing excess vessel injury. This study examines the effect of deep vessel wall injury on acute and late coronary arterial response after cutting balloon angioplasty. Serial volumetric intravascular ultrasound (IVUS) analyses were performed in 63 lesions treated with cutting balloon angioplasty alone. Before intervention, the longitudinal range of the lesion segment that included the smallest lumen area (LA) was determined as LA <4 mm(2) and/or LA stenosis >60%. The exact corresponding site at postintervention and follow-up was aligned using peri- and intravascular landmarks. Average vessel area (VA), plaque area (PA), and LA were measured. Lesion segments were categorized as with or without deep vessel wall injury, which was defined as the presence of plaque/vessel wall fracture extending to the sonolucent (medial) layer. Before intervention, the lesion vessel size of deep injury group was smaller than that of the nondeep injury group (p <0.05 for average VA and PA), whereas average lesion LA, lesion length, and reference vessel size did not differ. Immediately after cutting balloon angioplasty, the deep injury group showed a significant increase in VA (p <0.0001) and a lesser decrease in PA (p <0.01) compared with the nondeep injury group. During follow-up, the increase of VA tended to be greater in the deep injury group than in the nondeep injury group (p = 0.06), whereas the change of PA did not differ. Consequently, LA decrease was less in the deep injury group than in the nondeep injury group (p <0.05). From these results, it is suggested that deep vessel wall injury tends to occur in lesions with relatively small size and such lesions show favorable vessel response after cutting balloon angioplasty.     

Effects of focused force angioplasty: pre-clinical experience and clinical confirmation

Balloon angioplasty results in a combination of plaque compression and fracture, creation of intimal flaps and localized medial dissection, as well as the stretching and remodeling of the arterial wall. The application of eccentric pressure to the vessel wall allows for the balloon force to be focused along a specified line resulting in a reduction in vessel resistance with an improved or equivalent result at a lower pressure. The FX miniRAIL is a novel balloon angioplasty catheter that has two external wires that are compressed by the inflating balloon into the vessel wall. It was tested in comparison to conventional balloon injury in a porcine coronary model. At equivalent balloon artery ratios no increase in the length of dissections occurred, but a characteristic longitudinal "cut" was noted in the presence of the FX miniRAIL. A similar finding was demonstrated in sample human cases when interrogated by IVUS and OCT.     

切割球囊临床应用的有效性和安全性评价

目的 探讨切割球囊临床应用的安全性和有效性。方法 对131例患者142处狭窄病变进行切割球囊或切割球囊＋支架治疗。结果 142处狭窄病变行切割球囊治疗中4次失败，成功率为97.2%。切割球囊治疗支架内再狭窄、开口部病变、分叉病变和小血管弥漫性病变以及其他类型病变各为69处、16处、19处、7处和27处，7例切割球囊扩张后发生内膜撕裂，均为A型夹层，发生率为5.3%，术中无死亡和急性心肌梗死及其他严重血管并发症发生。失败原因与病变严重钙化以及切割球囊不能达到或通过狭窄部位有关。结论 切割球囊临床应用是安全面有效的。     

Dissections Following Excimer Laser-Assisted Angioplasty of Saphenous Vein Bypass Grafts: Analysis of Incidence and Effect of Adjunctive Balloon Angioplasty

Excimer laser angioplasty, when first developed for the treatment of coronary artery disease, appeared promising based on preliminary work suggesting minimal vessel wall damage with excimer laser ablation. The excimer laser has since been used in the treatment of bulky, saphenous vein graft (SVG) lesions. To investigate the significance of the laser-vessel wall interaction, we studied the incidence of laser-induced dissections as well as the effect of adjunctive balloon angioplasty, in a multicenter trial of 188 SVG lesions undergoing CVX-JOO™ excimer laser ablation. Adjunctive balloon angioplasty was performed at the discretion of the individual operators. Laser-induced dissections were angiographically evident in 78 (41%) of 188 SVG lesions following laser ablation. Most of these were mild (National Heart, I.ung, and Blood Institute [NHLBIJ A or B). Adjunctive balloon angioplasty was performed following 73% of laser ablations and tended to improve the severity of laser-induced dissections, including the successful recanalization of 7 of 9 laser-induced total occlusions. Of the 117 SVG lesions with either no dissection or only mild dissection (NIILBI A or B), only 4 worsened to a moderate or severe (NHLBl C-F) status after adjunctive balloon angioplasty. Vessel wall injury, manifested as dissection, frequentlv occurs following excimer laser angioplasty of SVG lesions. Most of these dissections are angio-graphicaliy mild, and, when severe, are effectively reduced by adjunclive balloon angioplasty. Further techniques, such as multiplex catheters or saline infusion, aimed at minimizing vessel wall injury from laser ablation, may be required to reduce the occurrence of laser-induced dissections.     

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.     

Morphology of chronic coronary occlusions and response to interventional therapy - a study by intracoronary ultrasound

Objectives. Balloon angioplasty of chronic coronary occlusions has a low procedural success and a high recurrence rate. Better tomographic insights into the lesion morphology may improve the interventional strategy and results. Methods. Intracoronary ultrasound was used during the recanalizaton procedure of 45 chronic coronary occlusions (2 weeks to 14 months; average 3.4 months) to determine the lesion morphology and to assess the angioplasty result. The luminal area and the plaque burden were measured proximal and distal to the occlusion, and within the occlusion. The ultrasonographic characteristics of the occlusive lesions were compared to 45 nonocclusive lesions of age-matched patients with stable angina pectoris. Results. Occlusive lesions were more often echodense as compared to nonocclusive lesions (35% vs. 20% p=0.10). In chronic occlusions a multi- layered plaque morphology was observed in 22%, and this morphology was not found in nonocclusive lesions. Angiographic characteristics were not related to the ultrasonographic morphology of the lesion. Despite similar vessel areas in occlusive and nonocclusive lesions, the balloon size selected according to the angiographic image was underestimated in occlusive lesions. Based on the quantitative ultrasound measurement the balloon size was increased from 2.6±0.3 mm to 3.3±0.5 mm in 53% of the lesions. This resulted in an increase of the luminal area from 3.51±0.92 to 5.08±1.43 mm² (p<0.001). The acute recoil after balloon angioplasty was similar (34±18%) in hypodense and echodense plaques, but was significantly higher in lesions with a multi-layered plaque morphology (49±22%; p<0.05). In 19 patients with severe dissections or extreme acute recoil (residual stenosis>50%) the use of a stent increased the luminal area from 3.94±0.81 to 7.51±1.71 mm² (p<0.001). Conclusion. Intracoronary ultrasound demonstrated a multi-layered plaque morphology in one fourth of the chronic occlusions. This type of plaque was associated with a significant acute recoil. The presence of diffuse atherosclerosis in neighbouring segments of chronic coronary occlusions leads to underestimation of the balloon size. Quantitative assessment by intracoronary ultrasound helped to optimize the balloon size leading to a significant luminal area gain. The detection of excessive acute recoil should be considered an indication for stent deployment.     

Intravascular ultrasound detected calcification of coronary lesions as a predictor of dissections after balloon angioplasty

Dissection after balloon angioplasty of coronary arteries may give rise to an unfavourable early outcome. Compared with coronary angiography, intravascular ultrasound (IVUS) allows more detailed characterisation of dissections. We investigated the incidence and the type of dissections after balloon angioplasty in calcified coronary lesions.IVUS was performed in 43 patients with 48 lesions before and after percutaneous balloon angioplasty. Significant calcification was defined as an are of more than 90° with typical acoustic shadowing. Dissections were classified as type A when the media was not involved by the dissection and as type B when media involvement had occured.In the group with significant calcification dissection was observed in 79 % of the cases vs. 38 % in the control group (p<0.03). Type B dissection was present in 71 % of the dissections in the calcified lesions vs. 15 % in the control group (p<0.02). The balloon diameter and the ratio of balloon area to vessel area was not different in both groups but the required pressure for the first complete balloon inflation was significantly greater in the group with calcified lesions (9.46±3.6 atm vs. 6.65±2.6 atm; p<0.001).Thus balloon angioplasty in calcified coronary lesions is more likely to lead to dissection which frequently involve the media.     

Intravascular ultrasound predictors of subacute vessel closure after balloon angioplasty or atherectomy

BACKGROUND: Factors leading to subacute vessel closure after percutaneous coronary intervention (PCI) have not been well established in lesions treated with balloon angioplasty or atherectomy. METHODS AND RESULTS: We used intravascular ultrasound (IVUS) to determine the pre- and post-PCI characteristics involved in subacute vessel closure after PCI. Of 3,403 patients undergoing IVUS imaging during coronary balloon angioplasty or atherectomy, 8 patients (0.2%) developed angiographically documented subacute vessel closure within 1 week post-PCI and were compared to a group matched by procedure date (within 6 months), age, gender, stable or unstable angina, lesion location and treatment (balloon angioplasty or atherectomy). IVUS identified at least one cause for subacute vessel closure in 87% of patients (vs 25% in matched lesions, p < 0.01). Causes were all procedure-related and included inadequate final lumen (60%), dissection (50%) and thrombus (25%). Pre-procedure lesion characteristics were not different from matched lesions. CONCLUSIONS: Subacute vessel closure after balloon angioplasty or atherectomy is mostly related to insufficient post-procedure lumen dimension or dissection.     

Mechanism of luminal gain with plaque excision in atherosclerotic coronary and peripheral arteries: assessment by histology and intravascular ultrasound

OBJECTIVES: Using intravascular ultrasound (IVUS) and histology, the purpose of this study was to evaluate the occurrence of arterial wall overstretch and Dotter effect following revascularization with a plaque excision (PE) catheter compared with balloon angioplasty. BACKGROUND: Previous studies have demonstrated the safety and feasibility of plaque excision for the treatment of de novo coronary and peripheral atherosclerotic disease. However, whether mechanical vessel dilatation related to catheter insertion contributes to gains in the final luminal diameter is uncertain. METHODS: Treatment with PE was assessed in both a porcine model (6 lesions treated with balloon angioplasty or PE) using histology and in humans with IVUS. In the latter part of the study, IVUS study was performed before and immediately following PE in 21 patients with either coronary artery disease (N = 13) or femoral artery disease (N = 8). Ultrasound measures in the femoral artery group were then compared with a control group of atherosclerotic lesions treated with conventional angioplasty that was matched according to lesion location and vessel diameter. RESULTS: Among individuals with coronary and peripheral arterial lesions treated with PE, the relative increases in luminal area secondary to reductions in plaque volume were 89% and 83%, respectively, with minimal increase in vessel diameter. In contrast, balloon angioplasty was associated with significantly greater vessel expansion and less plaque volume reduction. Vessel dissection also tended to occur less frequently and to a lesser extent with PE. CONCLUSIONS: Improvement in luminal dimensions using PE is principally due to a reduction in plaque volume rather than mechanical vessel expansion. The potential to increase luminal area while minimizing arterial dissection and barotrauma merits further clinical study with this method of revascularization.     

Intravascular ultrasonic comparisons of mechanisms of vasodilatation of cutting balloon angioplasty versus conventional balloon angioplasty

Intimal hyperplasia after balloon dilatation may be related to the severity of vascular injury, and cutting balloon angioplasty (CBA) may reduce vascular injury. The present study investigated the mechanism of vasodilation by CBA. Intravascular ultrasound examination was performed before and after intervention in 40 lesions treated with CBA and in 25 lesions treated with conventional balloon angioplasty. Intravascular ultrasound measurements included the vessel area, luminal area, and plaque area. Vessel expansion was evaluated as the ratio of the postprocedural vessel area to that before intervention. The vessel area was 13.9 +/- 3.2 and 14.8 +/- 3.2 mm(2) after CBA versus conventional angioplasty, respectively, whereas the luminal area was 5.5 +/- 1.2 versus 5.7 +/- 1.2 mm(2) and the plaque area was 8.5 +/- 2.7 versus 9.1 +/- 2.2 mm(2), respectively. The vessel area was smaller and the plaque area significantly smaller after CBA. Vessel expansion accounted for 45% of luminal enlargement, and plaque compression or shift accounted for 55% after CBA. After conventional angioplasty, vessel expansion accounted for 67%, and plaque compression or shift for 33% of luminal enlargement. The vessel expansion ratio was significantly smaller after CBA than after conventional angioplasty (1.05 vs 1.22, p <0.05). These findings suggest that the predominant mechanism of dilatation after CBA is plaque compression or shift rather than vessel expansion, unlike conventional angioplasty.     

Mechanisms of balloon angioplasty and directional coronary atherectomy as assessed by intracoronary ultrasound.

OBJECTIVE. This study was designed to use intracoronary ultrasound imaging to elucidate the physical effects of balloon angioplasty and directional coronary atherectomy in vivo in humans. BACKGROUND. The proposed mechanisms of coronary artery interventions such as balloon angioplasty and directional atherectomy are based on animal studies or pathologic findings and these data may not be applicable to living patients. Intracoronary ultrasound findings correlate highly with pathologic results and may allow in vivo assessment of the mechanisms of such interventions in humans. METHODS. Intracoronary ultrasound imaging was performed in 45 patients after a successful coronary intervention (balloon angioplasty in 30, directional coronary atherectomy in 15). Ultrasound images obtained at the treatment site and at an adjacent angiographically normal references site were analyzed quantitatively for minimal lumen diameter, cross-sectional lumen area, are enclosed by the internal elastic lamina, plaque area (internal elastic lamina area--lumen area) and percent area stenosis (plaque area/internal elastic lamina area). Qualitative analysis included assessment of presence of dissection, plaque composition and plaque topography. RESULTS. The results of the two procedures were similar with respect to minimal lumen diameter (angioplasty 2.6 +/- 0.5 vs. atherectomy 2.6 +/- 0.3 mm, p = NS), lumen area (0.07 +/- 0.03 vs. 0.07 +/- 0.02 cm2, p = NS) and percent area stenosis (59 +/- 14% vs. 51 +/- 21%, p = NS). However, after angioplasty, the internal elastic lamina area was significantly larger at the treated site than at the reference site (delta = +0.03 +/- 0.04 cm2, p = 0.01). There was no significant difference between the two sites after atherectomy (delta = -0.01 +/- 0.05 cm2, p = NS). In addition, dissection was seen significantly more often after balloon angioplasty than after atherectomy (50% vs. 7%, p less than 0.01). The results were similar when stratified for plaque composition and morphology. These data were confirmed in six additional patients who underwent ultrasound imaging before and after the intervention. CONCLUSIONS. Thus, the improvement in lumen dimensions after coronary balloon angioplasty is a result of both vessel stretch, demonstrated by a larger internal elastic lamina area at the treated site, and dissection. Both vessel stretch and dissection are uncommon after atherectomy, a finding consistent with plaque removal as the major mechanism for improved lumen area after this procedure.     

Update on Cutting Balloon Angioplasty

Cutting balloon (CB) is a unique balloon catheter with 3 or 4 metal blades on its surface making controlled endovascular surgical incisions that show promise of causing less vessel wall injury and less intimai proliferation. Multicenter randomized trials have revealed that CB angioplasty with multiple inflations achieved better lumen enlargement than single inflation and reduced coronary dissection more than plain old balloon angioplasty (POBA). Follow-up results showed CB angioplasty had a smaller late loss and loss index, resulting in lessened restenosis and target lesion revascularization rates. The main indication of CB angioplasty is basically a noncalcified lesion with concentric plaque; however, it could be applied effectively to some lesions unsuitable for POBA including in-stent restenosis, small vessel, long diffuse lesion, or ostial lesion. Additional evaluation would be necessary to determine the role of CB angioplasty in the stent era.     

Intravascular ultrasound evaluation of the effect of rotational atherectomy in obstructive atherosclerotic coronary artery disease.

BACKGROUND. High-speed rotational atherectomy uses a diamond-coated, elliptical burr to abrade occlusive atherosclerosis, especially noncompliant calcified plaque. METHODS AND RESULTS. Intravascular ultrasound (IVUS) was used to analyze 28 patients after atherectomy. Arteries treated and imaged were left main (three), left anterior descending (12), left circumflex (five), right coronary (seven), and saphenous vein graft (one). Twenty patients had adjunct balloon angioplasty. Twenty-two (79%) target lesions were calcified; the intimal arc of calcium was 160 +/- 126 degrees (range, 0-360 degrees). After atherectomy, the intima-lumen interface was unusually distinct and circular. The lumen was larger than the largest burr used for both stand-alone (1.19 +/- 0.19-fold the largest burr size) and adjunct balloon procedures (1.30 +/- 0.15-fold the largest burr). Three-dimensional reconstruction of the ultrasound images showed a smooth lumen, especially in calcified plaque. Deviations from cylindrical geometry occurred only in areas of soft plaque or superficial tissue disruption of calcified plaque. Five patients were studied before and after rotational atherectomy. IVUS showed an increase in lumen size, a decrease in plaque-plus-media area and in arc of target lesion calcification, and no change in target lesion external elastic membrane cross-sectional area. CONCLUSIONS. Rotational atherectomy causes atheroablation with only moderate evidence of barotrauma in heavily calcified arteries, even after adjunct balloon angioplasty. The lumen is cylindrical, especially in areas of calcified plaque, and somewhat larger than the largest burr tip used.     

High resolution magnetic resonance imaging of atherosclerosis and the response to balloon angioplasty

OBJECTIVE: To explore the use of high resolution magnetic resonance imaging (MRI) of the popliteal artery in defining atheroscelerotic lesions and to monitor the remodelling response to balloon angioplasty. METHODS: Four patients (aged 49-67) with symptomatic discrete popliteal artery stenoses, as demonstrated by conventional angiography, underwent balloon angioplasty. MRI of the diseased vessel was performed before and one week, one month, three months, and six months after therapeutic balloon angioplasty. Cine phase contrast MRI was used to estimate blood flow just proximal to the lesion before and after angioplasty. RESULTS: In all patients the extent of the atherosclerotic plaque could be defined, such that even in segments of vessel which were angiographically "normal", atherosclerotic lesions with cross sectional areas ranging from 49% to 76% of potential lumen area were identified. Following angioplasty, plaque fissuring and local dissection were easily identified and serial changes in lumen diameter, blood flow. and lesion size could be documented. CONCLUSIONS: High resolution MRI can define the extent of atherosclerotic plaque in the peripheral vasculature and demonstrate the changes that occur with remodelling and restenosis following angioplasty. As a safe, reproducible technique MRI is ideal for assessing plaque and monitoring intervention, but further technological developments will be needed if similar or better images are to be achieved in other vascular beds.     

Greater late lumen loss after successful coronary balloon angioplasty in the proximal left anterior descending coronary artery is not explained by extent of vessel wall damage or plaque burden

OBJECTIVES: We investigated whether the greater late lumen loss after coronary balloon angioplasty in the proximal left anterior descending artery (P-LAD) compared with that in other segments might be related to differences in vascular dimensions or morphology as determined by angiography and intravascular ultrasound imaging. BACKGROUND: The greater late lumen loss after angioplasty in the P-LAD that has been observed in several studies has not been explained. METHODS: We studied 178 patients and 194 coronary artery lesions by quantitative angiography and 30 MHz intravascular ultrasound imaging after successful balloon angioplasty. Vessel wall morphology was compared among three proximal and three nonproximal segments. Follow-up quantitative angiography for late lumen loss calculation was performed in 168 lesions. Multivariate analysis was used to determine predictors of late lumen loss. RESULTS: Absolute and relative late loss were significantly greater at the P-LAD compared with the pooled group of other segments (0.42 +/- 0.60 mm vs. 0.10 +/- 0.48 mm, p = 0.0008 and 0.14 +/- 0.24 vs. 0.03 +/- 0.17, p < 0.001). Also, a greater percentage of calcific lesions (65% vs. 44%, p = 0.034), a lower incidence of rupture (51% vs. 74%, p = 0.009) and a larger reference segment plaque area (5.4 +/- 2.2 mm2 vs. 4.7 +/- 1.9 mm2, p = 0.05) were found in the P-LAD. In multivariate analysis however, these variables were not predictive of late loss. CONCLUSIONS: Greater late lumen loss after coronary balloon angioplasty of the P-LAD is not explained by differences in atherosclerotic plaque burden or in vessel wall damage.     

Effect of intracoronary stenting on intimal dissection after balloon angioplasty: results of quantitative and qualitative coronary analysis

The effect of the Palmaz-Schatz stent on the angiographic appearance and residual luminal stenosis in patients with intimal dissection after balloon angioplasty was evaluated in 84 consecutive patients (90 lesions). Coronary angiography was performed before angioplasty, after conventional angioplasty and after stent implantation. The degree of intimal disruption was assessed as follows: grade 0, no dissection; grade 1, simple dissection (intraluminal linear defect or extraluminal cap extravasation); or grade 2, complex dissection (nonlinear spiral defect or luminal defect with multiple irregular borders). Quantitative coronary analysis of digitized cineangiograms was performed with use of a computerized automatic edge detection algorithm. After balloon angioplasty, 31 (34%) of 90 lesions demonstrated intimal dissection (18 simple, 13 complex). After stent implantation, intimal dissection improved by greater than or equal to 1 grade in 29 (94%) of the 31 lesions with 27 (87%) reduced to grade 0 (that is, no dissection). Dissection grade improved after stenting in 16 (89%) of 18 simple dissections and in all 13 complex dissections. Mean diameter stenosis was 77 +/- 17% before angioplasty, 47 +/- 17% after angioplasty and 14 +/- 10% after stenting (before angioplasty vs. after angioplasty and after angioplasty vs. after stenting, p less than 0.0001). In conclusion, intracoronary stenting is effective in reducing the residual luminal stenosis and in improving the angiographic appearance of intimal dissections after conventional balloon angioplasty.     

Coronary vessel stent implantation in patients with symptomatic dissections following balloon dilatation

Dissections after coronary balloon angioplasty are risk factors for acute or subacute vessel closure. Intracoronary stenting was developed to avoid this complication by wrapping the intimal and medial flaps against the vessel wall, which reduces the risk of acute thrombosis. A total of 17 stents were implanted into the coronary arteries of 10 patients with angiographically documented dissections after balloon angioplasty, who presented angina and ischemic ECG changes. Mean minimal stenosis diameter was 1.11 +/- 0.35 mm (65.1%) before, and 1.48 +/- 0.56 mm (53.9%, n.s.) and 2.45 +/- 0.62 mm (23.5%, p less than 0.005), respectively, after balloon angioplasty with and without taking the dissection membrane into account. All patients reported an immediate recovery of their anginal complaints after stent delivery, and ischemic ECG changes disappeared. The mean residual stenosis after coronary stenting was measured as 3.33 +/- 0.23 mm (0%, p less than 0.001). The immediate control angiograms and these after 24 h depicted smooth vessel walls without any irregulations at the site of implantation, and the mean residual stenosis diameter remained unchanged after 24 h (3.3 +/- 0.23 mm; 1.2%, p less than 0.001). No patient suffered acute myocardial infarction, one patient underwent coronary bypass surgery because of persisting episodes of angina pectoris. Thus, intracoronary stenting seems to be a secure and effective method to handle dissections after balloon angioplasty, and perhaps reduces the rate of acute complications and the need for emergency bypass surgery after coronary balloon angioplasty.