Neointimal Ingrowth Research Articles

Subtotal obstruction of the left coronary ostium by chronic neo-intimal ingrowth.

Subtotal obstruction of the left coronary ostium by chronic neo-intimal ingrowth.

Self-Expandable Stents in Vascular Stenosis of Moderate to Large-Sized Vessels in Congenital Heart Disease: Early and Intermediate-Term Results

Background and ObjectivesVascular stenosis after surgical repair frequently occurs in congenital heart disease. Although conventional balloon dilation is a useful option for stenotic lesions, restenosis may occur. Consequently, balloon expandable stents have been used; however, there are a limited number of balloon expandable stents in our country. Here, we report the early and intermediate-term outcomes of self-expandable stents in vascular stenosis of moderate to large-sized vessels in congenital heart disease.MethodsTwelve self-expandable stents were implanted in 9 patients between February 2012 and January 2019. The median age and weight were 12 years (range, 4–39 years) and 38 kg (range, 19–69 kg), respectively. The patients were followed-up for a median duration of 43 months (range, 1–83 months) after stent implantation.ResultsNine self-expandable stents were implanted in the pulmonary artery, 2 stents in the right ventricle to the pulmonary artery conduit, and 1 stent in the coarctation. The narrowest diameter of the stented vessel increased from 5.7±3.2 mm to 12.6±3.4 mm (p<0.05). The mean pressure gradient across the stenotic lesion decreased from 23.0±28.2 mmHg to 3.2±3.6 mmHg (p<0.05). Distal migration of the stent occurred in 1 patient, and significant neointimal ingrowth was noted in 1 patient.ConclusionsThe self-expandable stent may be a useful option to relieve vascular stenosis in moderate to large-sized vessels with acceptable intermediate-term outcomes.

Stenting of the left pulmonary artery after palliation of hypoplastic left heart syndrome.

Left pulmonary artery stenosis and hypoplasia is a well-recognized complication following surgical palliation of hypoplastic left heart syndrome. These lesions produce increased after load in a circulation in series so need to be effectively treated. Between 2000 and 2011, 86 patients after surgical palliation for hypoplastic left heart syndrome had left pulmonary artery stents implanted. Median age at implantation was 4.7(1.3-15.2)years and median weight was 16.4(9.3-55.2)kg. Uncovered peripheral vascular stents were implanted (median diameter 10(8-15)mm). This is a retrospective review of the incidence of in-stent restenosis over the medium to long term. During primary stenting procedures, there were 2/88(2.3%) major complications of stent migration with no stroke or mortality. Follow-up was for a median period of 4.1(0.5-13.4)years. Follow-up catheter procedures were performed after a median time of 2.3(0.02-9.6)years in 59 patients (68.6%). 55/59(93.2%) had at most mild restenosis (≤10% loss of stent lumen) and 47/59(79.6%) had no evidence of any restenosis at all caused by neointimal in-growth. Freedom from reintervention was 77% at 5 years including stent dilation to compensate for somatic growth. Freedom from reintervention for restenosis was 93% at 5 years. Restenosis was successfully treated with standard balloon angioplasty or restenting. There was only 1/94 (1.1%) major complication in the follow-up catheterizations of stent embolization with successful transcatheter retrieval. Stenting of the left pulmonary artery after Norwood/Fontan palliation is safe and effective. Stents can be redilated to match somatic growth. The incidence of neointimal proliferation is extremely low and can be addressed by balloon dilation or stent implantation. © 2016 Wiley Periodicals, Inc.

Left internal thoracic artery patch aortoplasty for repair of coarctation of the aorta

Adult patients with long coarctation of the aorta (CoA) may require coarctectomy and prosthetic tube or patch implantation. Potential drawbacks of these techniques, such as risk of infection, thrombosis, neointimal ingrowth, and aneurysm formation, are closely related to the use of prosthetic materials. 1-3 To avoid these specific risks, we developed a technique that includes resection of coarctation and two elements of plastic procedure: end-to-end suturing of the aorta posterior wall and patch closure of the longitudinally incised aorta anterior wall. The material for the patch is autologous left internal thoracic artery (LITA). Technique The approach is by left posterolateral thoracotomy through the fourth intercostal space. The length of the CoA and diameter of LITA are measured (Figure 1, A). If the LITA diameter is big enough, then a segment of this vessel is harvested within the area between the second and third intercostal spaces. The arterial cylinder is opened longitudinally to prepare a patch (Figure 1, B). After harvesting, the patch is preserved in sterile normal saline solution. The prestenotic and poststenotic parts of the isthmus of the aorta, coarctation, ligamentum arteriosum, left subclavian artery, and descending thoracic aorta are dissected. The ligamentum arteriosum is ligated and divided. After reduced heparinization (100 IU/kg intravenously), vascular clamps are placed on the aorta; the coarctation, together with ductal tissue, is then excised between the clamps. To achieve as wide as possible a lumen of the aortic anastomosis, two additional longitudinal incisions (approximately 20 mm each) are made: proximally on the isthmus toward the origin of left subclavian artery and distally on the descending aorta. Then the posterior wall of the anastomosis is constructed with 5-0 monofilament polypropylene continuous suture (Figure 2, A). The anastomosis is completed by suturing the LITA patch to the aorta within its longitudinally incised wall (Figure 2, B). The thoracotomy is closed after insertion of a chest drain.

Healing of carotid stents: a prospective duplex ultrasound study.

To study the dynamics of carotid stent healing over a 2-year period using duplex ultrasound imaging. One hundred twelve patients with 121 successfully stented carotid arteries were examined with color-coded duplex ultrasound the day after the stent procedure and at 1, 3, 6, 12, and 24 months in follow-up. The maximal thickness and echogenicity of the layer between the stent and the perfused lumen (SPL) were evaluated. Echogenicity was classified as echogenic if the SPL layer was clearly detected in B mode and echolucent if the SPL layer was barely visible in B mode, its border defined by assistance of color-coded flow. At day 1, an echolucent SPL layer with a median thickness of 0.7 mm was interpreted as a thrombotic layer, which decreased at 1 month to practically zero (i.e., not detectable). In follow-up, increases in thickness (mainly up to 6 months) and echogenicity (up to 12 months) of the SPL layer were interpreted as neointimal ingrowth. At 3, 6, and 12 months, the median maximal thickness of the SPL layer was 0.5 mm, 0.9 mm, and 1.0 mm, respectively, whereas the percentage of patients with an echogenic SPL layer was 27% (32/119), 56% (66/117), and 95% (105/110), respectively, at the same time intervals. No further change was observed at the 24-month examination. Three phases of carotid stent incorporation are defined: (1) an early unstable period soon after stent placement with an echolucent (thrombotic) SPL layer, (2) a moderately unstable phase with ingrowing neointima (1-12 months), and (3) a stable phase from the second year on. These data may indicate the need for different intensities of therapy and surveillance intervals.

Early and intermediate-term complications of self-expanding stents limit its potential application in children with congenital heart disease

OBJECTIVESWe report on the early and intermediate-term follow-up results of self-expanding Wallstent (Schneider, Switzerland) implanted in children with congenital heart disease.BACKGROUNDThe inherent shortcomings of balloon-expandable stents prompted the trial of an alternative stent.METHODSTwenty patients underwent 22 implantations of 25 self-expanding Wallstents between December 1993 and June 1997 in two institutions. The mean age and weight were 10.8 ± 4.5 years and 30.5 ± 14.2 kg, respectively. The patients were divided into two groups: 1) Group I comprised 17 patients with pulmonary arterial stenoses, 2) Group II comprised four patients with venous stenoses (one belonged to both groups). Sixteen patients underwent recatheterization at a median of 5.8 months (range 0.5 to 31, mean 8.1 months) after stenting. Hemodynamic and angiographic changes after the interventional procedures and complications were documented.RESULTSAll the stents were successfully deployed in the intended position. In Group I, the narrowest diameter of the stented vessel increased from 4.1 ± 1.5 to 8 ± 2 mm (95% increase, p < 0.0001) while the systolic pressure gradient across decreased from 24.6 ± 15.8 to 12.1 ± 11.4 mm Hg (51% decrease, p = 0.001). In Group II, the dimensional changes of the narrowest segment increased from 4.3 ± 0.5 to 7.5 ± 0.4 mm (75% increase, p = 0.003), and the pressure gradient reduced from 5.0 ± 2.9 to 0.9 ± 1.0 mm Hg (82% decrease, p = 0.04) across the stented venous channel. Distal migration of two optimally positioned stents occurred within 24 h of implantation. At recatheterization, significant neointimal ingrowth (>30% of the expanded diameter) was noted in 7 (28%) of the 25 implanted stents. This responded poorly to balloon dilation. Predisposing factors for the neointimal ingrowth included stents of smaller diameter (<9 mm) and longer period after implantation.CONCLUSIONSSelf-expanding Wallstent could be deployed easily and safely to relieve vascular stenoses in children. The complications of distal migration, significant neointimal ingrowth and its unyielding design to overdilation limit its application to this patient group.

Coronary wallstents show significant late, postprocedural expansion despite implantation with adjunct high-pressure balloon inflations

Adjunct high-pressure balloon inflations following the delivery of oversized self-expandable Wallstents may affect their implied late, postprocedural self-expansion. Consequently, we examined 15 “Magic” Wallstents, which were implanted following a strategy of stent oversizing and subsequent adjunct high-pressure balloon inflations (16 ± 2 atm; all ≥12 atm). The excellent radiographic visibility of this stent permitted reliable quantitative coronary angiographic measurement of both lumen and stent dimensions (before and after stenting, and at follow-up). At follow-up, extent and distribution of in-stent neointimal proliferation were evaluated with volumetric intravascular ultrasound. Between postintervention and follow-up examination, mean stent diameter increased from 3.7 ± 0.4 to 4.2 ± 0.4 mm (p <0.0001); there was no significant difference in late stent expansion between proximal, mid-, and distal stent subsegments. Late stent expansion showed a significant (reverse) relation to maximum balloon size (r = −0.56, p <0.04), but not with follow-up lumen size or late lumen loss. On average, 52 ± 18% of the stent was filled with neointimal ingrowth; neointimal volume/cm stent length was 64 ± 22 mm 3. Both late stent expansion (r = 0.36, p <0.02) and maximum balloon pressure (r = 0.41, p <0.001) were related to neointimal volume/cm stent but not to follow-up lumen size. Thus, despite high-pressure implantation, Wallstents showed significant late self-expansion, which resulted in larger stent dimensions at follow-up that assisted in accommodating in-stent neointimal proliferation. Conversely, late stent expansion had a significant relation to the extent of in-stent neointimal ingrowth. Beneficial and disadvantageous effects of the late stent expansion appear to be balanced, because a relation to late lumen loss or follow-up lumen dimensions was not found to be present.

ADVANCES IN CARDIAC SURGERY, VOLUME 8

The tortuous way cardiac surgery continues to evolve and the way its advance depends upon positive feedback from basic science is well illustrated in this potpourri of review articles. The essay on conduits in the pulmonary circulation, for example, laments the neointimal ingrowth, thrombus formation, and valve deterioration that imbrue this operation and make it one of the “ongoing weak links in reconstructive congenital heart surgery.” Molecular biological explanations for these commonly-observed problems are then given in two remarkably readable chapters on coagulation and intimal hyperplasia. How to inhibit or modulate vascular smooth-muscle cell proliferation in vein grafts (eg, with antisense oligonucleotides or by viral transfer of either genes or vascular cell adhesion molecules) is particularly well detailed.

Serial follow-up after optimized ultrasound-guided deployment of Palmaz-Schatz stents. In-stent neointimal proliferation without significant reference segment response.

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

Effects of cold storage on the subsequent structure and function of microvenous autografts

A study was undertaken to evaluate the structure and patency of cold stored rabbit femoral veins following reinsertion as autografts for 3 weeks. The periods of cold ischaemic storage were 1, 2, 3, and 4 weeks (n = 10/gp) and 6 and 10 weeks (n = 6/gp). All rabbits were subject to 3 operations under general anaesthesia. In the first, a 4 cm segment of left femoral vein was harvested and stored at 4°C for the specified ischaemic interval. Following storage the graft was microsurgically reinserted at a second operation into the right femoral artery of the donor rabbit. Three weeks later, graft patency was assessed by surgical exploration and the graft processed for light and electron microscopy. Patency rates remained over 80% after 3 weeks in all groups except the 10 week storage group where only 1 of 6 (17%) grafts was patent at 3 weeks. In all groups normal vein structure was absent, being replaced by thin walled necrotic areas or by neointimal ingrowth. The excellent patency rates achieved indicate it is possible to cold preserve extra lengths of vein grafts harvested at initial operation for reuse should regrafting be necessary.