Change In Vessel Area Research Articles

Assessment of changes in vessel area during needle manipulation in microvascular anastomosis using a deep learning-based semantic segmentation algorithm: A pilot study.

Appropriate needle manipulation to avoid abrupt deformation of fragile vessels is a critical determinant of the success of microvascular anastomosis. However, no study has yet evaluated the area changes in surgical objects using surgical videos. The present study therefore aimed to develop a deep learning-based semantic segmentation algorithm to assess the area change of vessels during microvascular anastomosis for objective surgical skill assessment with regard to the "respect for tissue." The semantic segmentation algorithm was trained based on a ResNet-50 network using microvascular end-to-side anastomosis training videos with artificial blood vessels. Using the created model, video parameters during a single stitch completion task, including the coefficient of variation of vessel area (CV-VA), relative change in vessel area per unit time (ΔVA), and the number of tissue deformation errors (TDE), as defined by a ΔVA threshold, were compared between expert and novice surgeons. A high validation accuracy (99.1%) and Intersection over Union (0.93) were obtained for the auto-segmentation model. During the single-stitch task, the expert surgeons displayed lower values of CV-VA (p < 0.05) and ΔVA (p < 0.05). Additionally, experts committed significantly fewer TDEs than novices (p < 0.05), and completed the task in a shorter time (p < 0.01). Receiver operating curve analyses indicated relatively strong discriminative capabilities for each video parameter and task completion time, while the combined use of the task completion time and video parameters demonstrated complete discriminative power between experts and novices. In conclusion, the assessment of changes in the vessel area during microvascular anastomosis using a deep learning-based semantic segmentation algorithm is presented as a novel concept for evaluating microsurgical performance. This will be useful in future computer-aided devices to enhance surgical education and patient safety.

Optical Coherence Tomography Angiography to Quantify Choroidal Neovascularization in Response to Aflibercept

Purpose: To investigate the microvascular changes in choroidal neovascularization (CNV) using optical coherence tomography angiography (OCTA) during anti-vascular endothelial growth factor (VEGF) therapies. Methods: We retrospectively collected data on consecutive treatment-naïve eyes with typical age-related macular degeneration that initially received 3 aflibercept injections. OCTA was performed at baseline and at 1, 2, and 4 months of follow-up. The CNV images were analyzed using open-source software to assess vessel area and junction density. Results: Fifteen eyes of 15 patients were included. The mean vessel area at baseline was 0.50 ± 0.33 mm²; at 1, 2, and 4 months, the ratios of change in vessel area from baseline were 66.6 ± 38.8%, 80.5 ± 25.5%, and 94.0 ± 29.3%, respectively. The vessel area was significantly reduced at 1 month from that at baseline (p = 0.0015) but significantly increased at 4 months from that at 1 month (p = 0.011). The mean junction density was also significantly reduced from 4.70 ± 1.30/mm at baseline to 3.82 ± 1.06/mm at 1 month (p = 0.00084). However, junction density did not continue to decrease at 2 and 4 months. Conclusion: OCTA quantification revealed that CNV rebounded after repeat aflibercept injections despite shrinking in response to the first injection.

Magnesium alloy covered stent for treatment of a lateral aneurysm model in rabbit common carotid artery: An in vivo study.

Magnesium alloy covered stents have rarely been used in the common carotid artery (CCA). We evaluated the long-term efficacy of magnesium alloy covered stents in a lateral aneurysm model in rabbit CCA. Magnesium alloy covered stents (group A, n = 7) or Willis covered stents (group B, n = 5) were inserted in 12 New Zealand White rabbits and they were followed up for 12 months. The long-term feasibility for aneurysm occlusion was studied through angiograms; the changes in vessel area and lumen area were assessed with IVUS. Complete aneurysmal occlusion was achieved in all aneurysms. Angiography showed that the diameter of the stented CCA in group A at 6 and 12 months was significantly greater than the diameter immediately after stent placement. On intravascular ultrasound (IVUS) examination, the mean lumen area of the stented CCA in group A was significantly greater at 6 and 12 months than that immediately after stent placement; the mean lumen area was also significantly greater in group A than in group B at the same time points. The magnesium alloy covered stents proved to be an effective approach for occlusion of lateral aneurysm in the rabbit CCA; it provides distinct advantages that are comparable to that obtained with the Willis covered stent.

Positive remodeling at 3 year follow up is associated with plaque free coronary wall segment at baseline: A serial IVUS study

AimsAt present it is unknown what limits the arterial remodeling process during atherosclerotic plaque formation. In healthy arteries remodeling is regulated by the shear stress induced response by the endothelium. As endothelium at the plaque site is assumed to be dysfunctional, we tested the hypothesis that plaque free wall (PFW) determines vascular remodeling during atherosclerotic plaque build-up. Methods & results66 human coronary ROIs (38 patients) were studied at baseline and at 3 years follow up applying intravascular ultrasound (IVUS). From the IVUS images the lumen and external elastic membrane contours were delineated to assess wall thickness (WT), vessel area (VA), Plaque Area (PA) and plaque burden (PA/VA*100%). WT < 0.5 mm was defined as normal and determined the arc of the PFW (0–360°). Positive remodeling was defined as relative difference of VA over time >5%. At baseline, IVUS-PFW was inversely related to plaque burden (p < 0.05). Positive remodeling was most frequently observed in ROIs with IVUS-PFW > 180° (i.e. larger than half of the circumference) compared to PFW < 180° (55% vs. 12%, p < 0.05). Accordingly, plaques with IVUS-PFW > 180° at baseline had the largest change in VA (1.1 ± 2.1 vs. −0.4 ± 0.6 mm2, p < 0.05) with an odds ratio of 9.2 to develop positive remodeling. ConclusionsOur serial IVUS data show that IVUS-PFW is a determinant of vascular remodeling. ROIs with PFW > 180 at baseline had the highest probability to undergo positive remodeling.

Vascular response at proximal and distal edges between polymer-free and polymer-based paclitaxel-eluting stents: intravascular ultrasound analysis

Aim: Polymer-based paclitaxel eluting stent (PB-PES) has shown to have a positive vascular remodeling at the distal edge compared to bare metal stent (BMS), probably due to higher downstream concentrations of the drug in comparison to proximal edge. The AXXION stent is a polymer-free paclitaxel eluting stent (PF-PES), whose dosage of drug is approximately 2.7 μg/cm2 compared to 1.0 μg/cm2 of the PB-PES. The purpose of this study was to compare vascular responses in adjacent segments between PF-PES and PB-PES. Methods and results: Consecutive 164 patients undergoing percutaneous coronary intervention were prospectively randomized 1:1 to receive either PF-PES or PB-PES (Clinicaltraials.gov [NCT01375855][1]). All patients provided written informed consent for their inclusion into IVUS examination at post-procedure and 9-month follow-up. Paired serial IVUS data were available in 76 patients with 84 lesions (38 patients with 41 lesions for PB-PES and 38 patients with 43 lesions for PF-PES). Baseline patient and lesion characteristics were similar between 2 groups. No significant differences were observed between PB-PES and PF-PES in terms of change in vessel area either at proximal (16.77±5.20% vs. 15.97±4.27%; p=0.450) or at distal segment (11.59±4.91% vs. 11.03±4.74%; p=0.546). No differences were also found in the percentage of change in plaque area (-5.73±42.81% for PB-PES vs. 9.81±32.91% for PF-PES; p=0.122) and in lumen area (0.43±19.42% for PB-PES vs. -5.70±17.87% for PF-PES; p=0.178) at proximal edge. Conversely at distal edge, a significant increase in plaque area was observed with PF-PES compared to PB-PES. (plaque area: 2.23±18.54% for PB-PES vs. 12.59±28.62% for PF-PES; p=0.038) with subsequent reduction in lumen area (5.82±21.18% for PB-PES vs. -4.98±17.59% for PF-PES; p=0.024). Conclusion: PF-PES did not seem to have a different edge response as compared to PB-PES. In particular they seem to increase plaque area with lumen reduction at the distal edge, probably due to differences in polymer-base drug release between the two platforms. [1]: /lookup/external-ref?link_type=CLINTRIALGOV&access_num=NCT01375855&atom=%2Fehj%2F34%2Fsuppl_1%2FP3945.atom

Three‐dimensional intravascular ultrasound evaluation of carina and plaque shift at the distal left main coronary artery bifurcation after treatment with a one‐stent cross‐over technique

To assess the geometrical changes in the distal left main coronary artery (LMCA), left anterior descending (LAD), and left circumflex (LCX) that occur after a distal LMCA lesion is treated using a one-stent cross-over strategy. Morphological changes after stent implantation into distal LMCA lesions are not fully understood. We used pre- and postintervention three-dimensional intravascular ultrasound of both the LAD and LCX as well as of the LMCA to evaluate distal LMCA lesions after a 1-stent cross-over strategy. In 38 distal LMCA bifurcation lesions, cross-sectional measurements were performed every 1 mm over a 5-mm segment in the LAD and LCX distal to the carina and over the entire LMCA proximal to the carina. The increase in lumen volume correlated with the increase in external elastic membrane volumes: R = 0.917, P < 0.001, in the LMCA and R = 0.785, P < 0.001, in the LAD with no decrease in plaque volume except at the distal end of the LMCA (P = 0.081) and at the LAD carina (P = 0.11). The LCX lumen area decreased significantly at the LCX carina from 5.9 ± 2.0 mm(2) to 5.3 ± 1.9 mm(2) (P < 0.01); however, the response was variable from a 4.0 mm(2) decrease to a 1.8 mm(2) increase in lumen area. While the change in LCX lumen area at the carina correlated with the change in vessel area (R = 0.791, P < 0.001), there was also a small increase in plaque area at the LCX carina from 6.4 ± 2.9 mm(2) to 6.8 ± 2.9 mm(2) (P < 0.01). LMCA bifurcation lumen changes after cross-over single-stent implantation were determined primarily by conformational changes in vessel geometry.

The Recanalization of Chronic Total Occlusion Leads to Lumen Area Increase in Distal Reference Segments in Selected Patients: An Intravascular Ultrasound Study

This study sought to investigate the extent of and factors related to lumen and vessel area change in coronary arteries after total occlusion (TO) recanalization. TO of a coronary artery promotes negative remodeling in distal reference segments. Recanalization can restore blood flow, potentially leading to positive vascular remodeling. From March 2005 to June 2008, 58 consecutive patients with de novo TO lesions of at least 1-month duration were enrolled. We performed intravascular ultrasound after successful percutaneous coronary intervention and at the 6-month follow-up, and we quantified changes in the distal reference segments. At the 6-month follow-up, there was a significant increase in the mean lumen diameter (+0.21 mm, p = 0.001), the mean external elastic membrane diameter (+0.13 mm, p = 0.010), the lumen area (+0.87 mm(2), p < 0.001), and the external elastic membrane area (+0.85 mm(2), p = 0.001) in the distal reference segments and an increase in the left ventricular ejection fraction (+2.77%, p = 0.010). Overall, 40 of 58 patients (69%) showed lumen area increase; these patients had increase in lumen diameter by 0.40 ± 0.34 mm (p < 0.001) and increase in incomplete stent apposition rate (p = 0.006). A TO duration of longer than 3 months (odds ratio [OR]: 14.8; 95% confidence interval [CI]: 1.28 to 172.8, p = 0.032), a poor collateral flow (OR: 12.0; 95% CI: 1.92 to 74.2, p = 0.008), and statin use (OR: 7.4; 95% CI: 1.03 to 53.6, p = 0.047) were independent predictors of lumen area increase. Recanalization of TO led to lumen area increase in two-thirds of the patients. Independent predictors of lumen area increase were occlusion duration, a poor collateral flow, and statin use. These factors could be used as guides in choosing the optimal stent size during percutaneous coronary intervention to TO lesions and optimal medical therapy during follow-up.

Quantification of aortic elasticity: development and experimental validation of a method using computed tomography

Aortic distensibility depending on aortic cross-sectional area changes is an important parameter for the grading of vascular diseases. This study measured aortic area changes by multidetector computed tomography. An image reconstruction algorithm was developed to assess aorta diameter and area as a function of the cardiac cycle with sufficient time resolution along the entire length of the aorta by four-detector row computed tomography. The algorithm was tested on porcine aortic specimens and compared with an optical reference method. The error of the relative vessel area change comparing the two methods was found to be about 3%. Initial tests on patient datasets indicate that clinical application is feasible. The proposed method has the advantage that it can easily be integrated into a modified routine CT angiography study and allows the measurement of aortic cross-sectional area changes.

Effect of a change in gender on coronary arterial size: A longitudinal intravascular ultrasound study in transplanted hearts

ObjectivesWe sought to document whether a physiologic change in gender has any effect on coronary arterial size. BackgroundThe coronary arteries are smaller in women, even after correction for body surface area (BSA). These differences may contribute to adverse clinical outcomes after coronary artery bypass graft surgery and myocardial infarction in women. In male and female transsexuals, pharmacologic doses of estrogens and androgens significantly influence vascular diameter. Thus, gender differences in the coronary vasculature may be a reflection of the hormonal environment. MethodsIn 86 patients who had undergone orthotopic heart transplantation, serial intravascular ultrasound studies of the proximal left anterior descending coronary artery (LAD) were analyzed. Changes in vessel area (VA) over the first or second post-transplant year were recorded, and comparisons were made between donor hearts that were transplanted in a patient of the same gender and those that were transplanted in a patient of the opposite gender. ResultsVessel area of the proximal LAD increased over time in all patient groups. In hearts transplanted within the same gender and in male donor hearts transplanted to female recipients, the change was small and not significant. However, in hearts transplanted from female donors to male recipients, there was a substantial and highly significant increase in LAD VA (median 16.13 to 17.88 mm2; p = 0.01). This increase was not explained by confounding due to changes in BSA or left ventricular wall thickness. ConclusionsThis pattern of arterial remodeling early after heart transplantation supports a link between host gender and coronary arterial size.

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.)

Gamma radiation induces positive vascular remodeling after balloon angioplasty: A prospective, randomized intravascular ultrasound scan study

Background: Endovascular brachytherapy (EBT) has been shown to prevent restenosis after percutaneous transluminal coronary angioplasty (PTA) in both animal and clinical studies. However, as yet, the effect of EBT on peripheral arteries is unknown. Objective: This intravascular ultrasound scan (IVUS) study evaluates the effect of EBT on the extent of plaque growth and vascular remodeling after PTA of the femoropopliteal artery. Methods: Twenty-four patients with obstructive disease of the femoropopliteal artery underwent standard PTA. Patients were randomized to receive no additional therapy or additional EBT (192-Iridium) after PTA. IVUS investigation was performed after PTA and at 6-month follow-up. A comparison was made between patients without EBT (n = 16) and with EBT (n = 8) in the change in lumen, vessel, and plaque area and plaque dissections seen with IVUS at 6-month follow-up. Results: At follow-up, IVUS revealed a significant difference in lumen area change between patients without and with EBT (−9% and +23%, respectively; P = .03). This difference was the result of a significant difference in vessel area change (+2% and +19%, respectively; P = .05). In both groups of patients, a similar increase in plaque area (+12% and +16%, respectively; P = .80) was encountered. Plaque dissections encountered immediately after PTA were absent at follow-up in patients without EBT, whereas in four of the eight patients with EBT, a persistent dissection was encountered. Conclusion: This randomized IVUS study showed that γ-radiation after PTA has a positive effect on lumen dimensions at 6-month follow-up by inducing positive vascular remodeling (ie, vascular dilatation); γ-radiation seemed not to affect plaque growth. In addition, γ-radiation has an effect on the healing process of dissections after PTA. (J Vasc Surg 2002;36:318-24.)

Role of plaque proliferation in late lumen loss after directional coronary atherectomy.

Previous reports suggest that vessel remodeling is the most important factor in late lumen loss in non-stented lesions, but because results of directional coronary atherectomy (DCA) show that increased plaque area (PA) is also important, the aim of this study was to redefine the mechanism of late lumen loss after DCA. One hundred and twenty lesions that underwent DCA with intravascular ultrasound (IVUS) guidance and serial IVUS analysis were studied, and vessel area (VA), lumen area (LA), PA (VA-LA) and corrected values (each value divided by the value of VA pre procedure to correct the vessel size) were analyzed. During follow-up, corrected VA (cVA) decreased by 0.058 +/- 0.191, whereas corrected PA (cPA) increased by 0.087 +/- 0.159. Though the %PA (PA/VA) after the procedure showed significant negative correlation with the subsequent change in cPA, it did not correlate with the subsequent change in cVA. In conclusions, the mechanism of late lumen loss after DCA consists of both arterial remodeling and plaque proliferation, and the residual %PA after the procedure determines the subsequent lumen loss. With a lower %PA, a change in the PA contributes more to late lumen loss than do changes in VA. With a high %PA, a change in the VA contributes more to late lumen loss.

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

OBJECTIVESThe purpose of this study was to assess the impact of pre-intervention arterial remodeling on subsequent vessel behavior following balloon angioplasty.BACKGROUNDPositive 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.METHODSSerial (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.RESULTSPre-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).CONCLUSIONSLesions 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.

The topography of intimal thickening and associated remodeling pattern of early transplant coronary disease: influence of pre-existent donor atherosclerosis

Background: With native coronary disease, intimal plaque initially accumulates at focal areas in the artery, often accompanied by compensatory vessel enlargement. With transplant coronary disease, the topography of intimal thickening and associated remodeling pattern are less studied. Methods: We studied 72 prospectively recruited transplant patients with serial intravascular ultrasound using 4.3F catheters at baseline and at 1-year follow up. We considered 175 ultrasound-recorded segments (mean, 2.4 ± 1.1 segments per patient) exactly matched on the serial studies by both angiographic criteria and ultrasound criteria, using arterial and venous branch points, pericardium, and sinuses as anatomic landmarks. Results: Eighty-eight segments had no donor disease, and 87 had donor disease (80 eccentric and 7 concentric intimal thickening). Progressive intimal thickening occurred in 48 segments without (55%) and 43 segments with donor disease (48%, p = NS). Thickening from segments without donor disease was mainly eccentric (81%). Thickening from segments with donor eccentric plaque was also mainly eccentric (67%, p = NS compared with segments without donor disease), with further thickening superimposed on the original plaque. Concentric intimal thickening was uncommon. Of the 58 patients who had >1 segment matched, intimal changes were discordant in 34 (59%), with progression in some and lack of progression in other segments. Total vessel area change correlated with intimal area change ( r = 0.37 with a slope of 0.79, p < 0.001), including segments with ( r = 0.39; slope, 0.69) and segments without ( r = 0.37; slope, 1.16) donor disease. Conclusion: The intimal thickening of early transplant coronary disease is mainly eccentric and often discordant within each individual patient. Donor eccentric plaque often serves as a nidus for further intimal growth. The topography of intimal thickening in transplant coronary disease resembles that of native coronary disease, but the presence of a pre-existent donor plaque may impede compensatory remodeling as further intimal thickening occurs after transplantation.

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

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. 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% <or= VA loss <or= +5%), and constrictive remodeling (VA loss > +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. 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.

Arterial remodeling. Mechanisms and clinical implications.

The presentation of coronary atherosclerosis can be gradual, because of progressive flow-limiting stenosis and exertional angina, or dramatic, with plaque rupture and thrombosis causing unstable angina, myocardial infarction, or sudden death. The importance of arterial remodeling, or persistent change in vessel size, has recently become apparent in both situations. Arterial remodeling, not plaque size, has been identified as the primary determinant of lumen size in the presence of stable lesions. Similarly, luminal stenosis in transplant vasculopathy and with restenosis after angioplasty occur mainly because of inward remodeling rather than plaque growth. However, recent evidence also suggests that adequate outward remodeling may be associated with an increased risk of plaque rupture, the underlying cause of acute coronary syndromes and sudden cardiac death. The term “arterial remodeling” has previously been used to describe any change in vessel wall structure. More recently, however, it has been used specifically to refer to a change in vessel size (or cross-sectional area within the external elastic lamina), and it is on this entity that this review is focused. Inward remodeling denotes a reduction in vessel size. Outward remodeling denotes an increase in vessel size. Various other terms are used in the literature (the Table⇓). When outward remodeling is present but insufficient to prevent luminal stenosis, it is referred to as inadequate outward remodeling. View this table: Table 1. Terminology of Arterial Remodeling It has been known for more than a century1 that blood vessels enlarge to accommodate increasing flow to the organ downstream (eg, during natural growth or in left ventricular hypertrophy). Widespread interest in this phenomenon was stimulated by observations that radial enlargement of vessels (outward remodeling) can compensate for progressive growth of atherosclerotic plaques, thus postponing the development of flow-limiting stenosis.2 3 These pathological findings were subsequently supported by in vivo intravascular ultrasound (IVUS) studies that …

Augmentation of vessel squeezing at coronary-myocardial bridge by nitroglycerin: Study by quantitative coronary angiography and intravascular ultrasound

Background Nitroglycerin is known to augment vessel wall squeezing at the site with coronary-myocardial bridging (CMB). This study was designed to define the mechanism of nitroglycerin-induced augmentation of CMB in clinical settings. Methods We analyzed nitroglycerin reactivity at the site with CMB in 39 patients. Maximal and minimal diameters of CMB during a cardiac cycle were measured by quantitative angiography before and after intracoronary administration of 250 μg nitroglycerin. In 15 patients, CMB sites were observed by intravascular ultrasound to determine the intimal thickness and the time-serial change in vessel area. Results Before nitroglycerin, CMB was demonstrated with angiography in 25 patients, and the remaining 14 patients showed CMB after nitroglycerin. The maximal diameter during diastole increased from 1.4 ± 0.4 mm to 1.9 ± 0.4 mm after nitroglycerin, whereas the minimal diameter during systole decreased from 1.0 ± 0.4 mm to 0.7 ± 0.4 mm ( P < .01). Thus nitroglycerin augmented the percent vessel narrowing during systole from 24% ± 21% to 65% ± 16% ( P < .01). Under these conditions, intravascular ultrasound showed the reduction of the cross-sectional area of the sites with CMB by –38% ± 16% ( P < .01) during systole, and this phenomenon continued to early diastole (–30% ± 16%). The intimal thickness was 0.32 ± 0.10 mm, which suggests the absence of atherosclerotic disease at CMB sites. Conclusions These results indicate that nitroglycerin-induced augmentation of the percent narrowing of CMB can be derived from further systolic compression of the vessel lumen as well as diastolic expansion, probably because of the increase in vessel compliance after nitroglycerin. We suggest that the delayed dilation of coronary lumen during the early diastole may contribute to the occurrence of myocardial ischemia. (Am Heart J 1999;138:345-50.)

Plaque area increase and vascular remodeling contribute to lumen area change after percutaneous transluminal angioplasty of the femoropopliteal artery: An intravascular ultrasound study

Objective: The aim of the study was to assess the change in lumen area (LA), plaque area (PLA), and vessel area (VA) after percutaneous transluminal angioplasty (PTA) of the femoropopliteal artery. Methods: This was a prospective study. Twenty patients were studied with intravascular ultrasound (IVUS) immediately after PTA and at follow-up examination. Multiple corresponding IVUS cross-sections were analyzed at the segments that were dilated by PTA (ie, treated sites; n = 168), including the most stenotic site (n = 20) and the nondilated segments (ie, reference sites; n = 77). Results: At follow-up examination, both the PLA increase (13%) and the VA decrease (9%) resulted in a significant LA decrease (43%) at the most stenotic sites ( P = .001). At the treated sites, the LA decrease (15%) was smaller and was caused by the PLA increase (15%). At the reference sites, the PLA increase (15%) and the VA increase (6%) resulted in a slight LA decrease (3%). An analysis of the IVUS cross-sections that were grouped according to LA change (difference ≥10%) revealed a similar PLA increase in all the groups: the type of vascular remodeling (VA decrease, no change, or increase) determined the LA change. At the treated sites, the LA change and the VA change correlated closely ( r = 0.77, P < .001). At the treated sites, significantly more PLA increase was seen in the IVUS cross-sections that showed hard lesion or media rupture ( P < .05). No relationhip was found between the presence of dissection and the quantitative changes. Conclusion: At the most stenotic sites, lumen narrowing was caused by plaque increase and vessel shrinkage. Both the treated sites and the reference sites showed a significant PLA increase: the type of vascular remodeling determined the LA change at follow-up examination. The extent of the PLA increase was significantly larger in the IVUS cross-sections that showed hard lesion or media rupture. (J Vasc Surg 1999;29:430-41.)

Impact of cilostazol on intimal proliferation after directional coronary atherectomy

Cilostazol, a novel platelet aggregation inhibitor, inhibits intimal proliferation in animal models. We randomly assigned 41 patients with lesions suitable for directional coronary atherectomy to the cilostazol group (200 mg/day) or the aspirin (250 mg/day) group. Medication was started before directional coronary atherectomy and was continued to a 6-month follow-up. Serial quantitative coronary angiography and intravascular ultrasound study were performed. Baseline characteristics were not different between the two groups. However, the minimal lumen diameter at follow-up was larger (2.33 ± 0.60 mm vs 1.81 ± 0.68 mm, p = 0.016) and the percent diameter stenosis (24.5% ± 16.6% vs 40.9% ± 21.0%, p = 0.010) was smaller in the cilostazol group. The change in vessel area was not different, but the percent plaque area at follow-up was smaller in the cilostazol group (55.7% ± 11.2% vs 64.5% ± 14.5%, p = 0.044). The restenosis rate was significantly lower in the cilostazol group (0% vs 26%, p = 0.020). We conclude that cilostazol appears to have an inhibitory effect on intimal proliferation after directional coronary atherectomy and may reduce restenosis. (Am Heart J 1998;135:495-502.)

Remodeling of human coronary arteries undergoing coronary angioplasty or atherectomy.

Recently, long-term constriction of the vessel has been suggested as an alternative mechanism of restenosis after coronary angioplasty. To understand remodeling of human coronary arteries undergoing coronary angioplasty or atherectomy, serial intravascular ultrasonographic examinations were performed at preintervention and postintervention examinations and at 24 hours, 1 month, and 6 months. Complete serial data were obtained in 61 lesions (balloon angioplasty, 35 lesions; directional atherectomy, 26 lesions). Lumen area improved from 6.81+/-2.24 mm2 after intervention to 8.22+/-2.79 mm2 at 1 month (P=.0001) and decreased to 4.88+/-2.86 mm2 at 6 months (P=.0001). Vessel area enlarged from 17.32+/-5.35 mm2 after intervention to 19.39+/-5.33 mm2 at 1 month (P=.0001) and decreased to 16.33+/-5.54 mm2 at 6 months (P=.0001). Plaque+media area increased significantly from postintervention examination to 24 hours (10.51+/-4.38 versus 10.96+/-4.49 mm2, P=.0008) and from 24 hours to 6 months (10.96+/-4.49 versus 11.45+/-4.45 mm2, P=.03). Changes in lumen area in each study interval correlated more closely with changes in vessel area than with changes in plaque+media area. Restenotic lesions compared with nonrestenotic lesions had a greater decrease in the vessel area between 1 month and 6 months (-4.33+/-2.73 versus -2.49+/-2.15 mm2, P=.006) and greater increase in the plaque+media area both within 24 hours (0.84+/-1.22 versus 0.27+/-0.38 mm2, P=.04) and between 24 hours and 6 months (1.19+/-2.19 versus 0.18+/-1.46 mm2, P=.04). CONCLUSIONS; Remodeling after coronary angioplasty or atherectomy was characterized by early adaptive enlargement and late constriction of the vessel.