Larger Luminal Area Research Articles

Evaluation of Choroidal Vascular Structure in Hyperopic Anisometropic Amblyopia.

The aim of the study was to investigate the choroidal structure of patients with anisohypermetropic amblyopia compared to that of healthy eyes in controls of the same age. The study comprises three groups: One group was the amblyopic eyes of patients with anisometropic hypermetropia (AE group), another group was the fellow eyes of patients with anisometropic hypermetropia (FE group), and a final group of healthy controls. Both the choroidal thickness (CT) and choroidal vascularity index (CVI) values were obtained using the spectral-domain optical coherence tomography (OCT) method of improved depth imaging (EDI-OCT; Heidelberg Engineering GmbH, Spectralis, Germany, Heidelberg). This study included 28 anisometropic amblyopic patients (AE and FE groups) and 35 healthy controls. Regarding the distribution of ages and sexes (p=0.813 and p=0.745), the groups were the same. The mean best-corrected visual acuity in AE, FE, and the control group was 0.58±0.76, 0.008±1.30, and 0.004±1.20 logMAR units, respectively. There was a significant difference in terms of CVI, luminal area (LA), and all the CT values between groups. Post hoc univariate analyses indicated that CVI and LA were significantly higher in AE compared to FE and the control group (p<0.05, for each). The temporal, nasal, and subfoveal CT values were considerably higher in AE compared to FE and the control groups (p<0.05, for each). However, there was no difference between FE and the control group (p>0.05, for each). The AE group had larger LA, CVI, and CT values compared to the FE and control groups. These results show that choroidal changes in amblyopic eyes in children are permanent in adulthood if untreated and are involved in the pathogenesis of amblyopia.

Assessment of choroidal vascularity and choriocapillaris blood perfusion in Chinese preschool-age anisometropic hyperopic amblyopia children.

To determine the macular and peripapillary area choroid microstructure parameters of hyperopic anisometropic amblyopia eyes and compare to fellow and age-matched control eyes. To assess the correlation between the axial length (AL), choroidal thickness (CT) and choroid microstructure parameters. This cross-sectional comparative, non-interventional study involved 52 hyperopic anisometropic amblyopia children and 48 age-matched heathy controls. 52 eyes with hyperopic anisometropic amblyopia and 48 age-matched control eyes were studied. The peripapillary and subfoveal CT were determined. The total choroidal area (TCA), luminal area (LA), and stromal area (SA) of the subfoveal and peripapillary choroid were measured. In addition, the correlation between the AL, CT and choroid microstructure parameters were calculated. The peripapillary and subfoveal CT of the amblyopic eyes was significantly thicker than the fellow and control eyes (all P < 0.05). The subfoveal and peripapillary choroidal SA, LA and TCA of the amblyopic eyes were significantly increased than that of the fellow and control eyes (all P < 0.05). The choroidal vascularity index (CVI) values of the amblyopic eye were significantly different among the three groups (P < 0.05). There was a statistically significant negative correlation between AL and subfoveal CT (SFCT), LA and TCA levels (P < 0.001, P = 0.039, P = 0.027, respectively). Spherical equivalent (SE) was positive correlated with SFCT, LA and TCA levels (P = 0.456, 0.229 and 0.240, respectively; all P < 0.05). There was a statistically significant positive correlation between SFCT, SE, LA, SA, TCA and CVI levels (all P < 0.05). The subfoveal and peripapillary CT of amblyopic children abnormally increased and correlated with shorter AL and higher SE. The choroidal structure of the amblyopic eyes was different from the fellow and control eyes, the hyperopic anisometropic amblyopic eyes had significantly thicker sub-foveal choroid, higher LA, SA, and TCA. AL and CT affect choroidal structure and vascular density. Choroidal blood flow may be increased in amblyopic eyes. The larger LA, SA, TCA, and lower CVI were characteristic of the amblyopic eye.

Abstract 321: The Aortic Luminal Area is a Potential Marker of Increased Rupture Risk in AbdominalAorticAneurysms

Introduction: Diameter is currently the only factor used to estimate rupture risk of abdominal aortic aneurysms (AAAs). Many large AAAs, however, do not rupture, and a significant portion of small AAAs do. Our aim was to investigate if simple two-dimensional geometric measurements can improve rupture risk prediction in AAAs, and relate these measurements to biomechanical determinants of AAAs. Methods: Thirty patients with ruptured AAAs (mean age was 77 ± 5 years and 23 were male) and 60 patients (mean age 60 ± 8 years, and 46 were male) with asymptomatic AAAs were included. At the location of the maximal diameter, the diameter, the luminal area and the vessel area were measured. Finite element analysis was used to compute 3D-geometric and biomechanical parameters of the asymptomatic AAAs, using A4 Clinics Software (VASCOPS, Austria). An automatic matching function was used to construct diameter-matched groups. Results: Analysis of all stable AAAs (n=60) and ruptured AAAs (n=30) showed that ruptured AAAs had a significantly larger diameter, 77 ± 15 mm vs. 62 ± 13 mm (p&lt;0.01) and significantly larger luminal area 2281 ± 1964 mm 2 vs. 1059 ± 674 mm 2 (p&lt;0.01). In order to control for diameter as a confounder, two diameter-matched groups, one with ruptured AAAs (n=28) and one with stable AAAs (n=15) were formed (74 ± 12 mm vs 73 ± 11, p = .67). Diameter-matched ruptured AAAs had a larger luminal area (1954 ± 1254 mm 2 vs. 1120 ± 623 mm 2 , p = .02) and a lower relative ILT area (55 ± 24 % vs 68 ± 24%, p= .03). In multivariate regression of 60 asymptomatic AAAs, including the maximal diameter, the luminal area explained the largest amount of variance in the biomechanical rupture risk parameters, followed by the ILT-area. Conclusions: We demonstrate that the luminal area is increased in ruptured AAAs compared to stable AAAs. Further, we show that this finding may in part be explained by a correlation between luminal area and biomechanical rupture risk parameters.

Comparative effects of sirolimus-eluting versus bare metal stents on neointimal hyperplasia in balloon-injured external iliac artery of rabbits

The aim of this study was to check effectiveness of drug-eluting stents for prevention of restenosis resulting from neointimal hyperplasia. Twenty-one sirolimus-eluting stents (SESs) and bare metal stents (BMSs; control) were compared by implantation into left and right balloon-injured external iliac arteries of New Zealand White rabbits, respectively. Under general anesthesia and angiography, using 3-mm coronary balloon catheters, stents were successfully deployed. Anticoagulant therapy was not given to any animal. Rabbits were allotted into three groups at 7, 14, and 21 days (7 rabbits in each group). Each stented vessel of sacrificed rabbits was subjected to a resin-embedding technique and methyl methacrylate sections were obtained using a tungsten carbide knife for staining. In histological examination, SESs showed marked reductions in almost all parameters. Morphometric results showed that arteries with SESs had a larger luminal area (P < 0.0001), lower intimal (P < 0.001) and medial (P < 0.001) thickness, and lower intimal index (P < 0.003) as opposed to arteries stented with BMSs. Luminal narrowing in SESs was 0% and reendothelialization was similar in both stented groups (90.48%). SESs showed marked reduction in nonocclusive peristrut fibrin deposition versus BMSs. Thus, the SES was more effective for prevention of restenosis than the BMS in rabbit.

Influence of Calcium Score on the Severity of Moderate Coronary Lesions Evaluated by Intravascular Ultrasound

The minimal luminal area (MLA) measured by intravascular ultrasound (IVUS) is a predictor of cardiovascular events in patients with angiographically moderate lesions. On the other hand, the presence of calcium is a predictor of lesion stability. The objective of this study is to evaluate the influence of the total amount of coronary calcium, obtained by multislice CT scanner (MDCT), on the severity of moderate lesions as assessed by IVUS. IVUS was performed in 27 moderate lesions in a consecutive series of 22 patients with indication for the procedure who had a previous MDCT. Measurements of the minimal luminal area (MLA), plaque burden and percentage area stenosis were obtained. Most patients were male (85%), with mean age of 60 ± 9 years and 41% were diabetic. A significant correlation was observed between the MLA and total calcium score (r = 0.67; P = 0.002), but there was no correlation between the total calcium score and plaque burden (r = 0.02; P = 0.93) or percentage area stenosis (r = 0.3; P = 0.32). Independent predictors of MLA in the multivariate analysis were age (P = 0.02), body mass index (P = 0.01), diabetes (P = 0.02), dyslipidemia (P = 0.02), high-sensitive C-reactive protein (P = 0.02), glucose (P = 0.02), HDL-cholesterol (P = 0.02), triglycerides (P = 0.02), left ventricular ejection fraction < 50% (P = 0.02) and total calcium score (P = 0.03). The total calcium score correlates positively with MLA in coronary arteries, suggesting that a large calcium burden in the coronary tree is related to angiographically moderate lesions with larger luminal areas at IVUS. Influência do Escore de Cálcio na Gravidade de Lesões Coronárias Moderadas Avaliadas pelo Ultrassom Intracoronário A área luminal mínima (ALM), obtida pelo ultrassom intracoronário (USIC), é preditora de eventos em pacientes com lesões de moderada gravidade, identificadas à angiografia coronária. Por outro lado, a presença de cálcio é preditora de estabilidade das lesões. O objetivo deste estudo é avaliar qual a influência da quantidade total de cálcio coronário, obtido pela tomografia computadorizada cardíaca (TCC), na gravidade de lesões moderadas, avaliadas por meio de USIC. Realizamos USIC de 27 lesões moderadas, em uma série consecutiva de 22 pacientes com indicação para o procedimento, e que tinham TCC prévia. Foram obtidas medidas da ALM, carga de placa e porcentual de área de estenose. Os pacientes eram, em sua maioria, do sexo masculino (85%), com idade de 60 ± 9 anos e 41% eram diabéticos. Observamos correlação significativa entre ALM e escore de cálcio total (r = 0,67; P = 0,002), mas não houve correlação entre escore de cálcio total e carga de placa (r = 0,02; P = 0,93) ou porcentual de área de estenose (r = 0,3; P = 0,32). Os preditores independentes da ALM na análise multivariada foram idade (P = 0,02), índice de massa corporal (P = 0,01), diabetes (P = 0,02), dislipidemia (P = 0,02), proteína C-reativa ultrassensível (P = 0,02), glicemia (P = 0,02), HDL-colesterol (P = 0,02), triglicerídeos (P = 0,02), fração de ejeção do ventrículo esquerdo < 50% (P = 0,02) e escore de cálcio total (P = 0,03). O escore de cálcio total apresenta correlação positiva com a ALM em artérias coronárias, sugerindo que maior quantidade de cálcio na árvore coronária implica lesões ateroscleróticas moderadas com maiores áreas luminais ao USIC.

Two-Year Clinical Outcome after Carvedilol-Loaded Stent Implantation in Patients with Coronary Artery Disease

Background/AimsCarvedilol is an antioxidant that inhibits smooth muscle cell proliferation and migration. The aim of this study was to investigate the beneficial effects of carvedilol-loaded stents on 2-year clinical outcomes after stent implantation in patients with coronary artery disease.MethodsWe performed a prospective trial with male subjects to compare the safety and effects of carvedilol-loaded BiodivYsio® stents implanted into 20 patients with those of bare-metal BiodivYsio® stents implanted into 21 patients for de novo coronary lesions. The primary end point was the degree of neointimal hyperplasia, which was measured by intravascular ultrasound (IVUS) 6 months after the procedure; the secondary end point was major adverse cardiac events (MACE) at 2 years after implantation. All carvedilol and control stents were deployed successfully.ResultsA 2-year follow-up was completed for 19 patients (95%) in the carvedilol stent group and 20 patients (95%) in the control stent group. IVUS showed a trend toward a larger luminal area (6.86 ± 2.59 vs. 5.47 ± 1.52 mm2, p = 0.267), smaller neointimal area (1.34 ± 0.70 vs. 2.40 ± 1.73 mm2, p = 0.18), and reduced net decrease in luminal area (-0.78 ± 0.97 vs. -1.89 ± 1.78 mm2, p = 0.106) in the carvedilol stent group compared with the control stent group, respectively. There were no significant differences in the incidence of MACE (10.5 vs. 30.0%, respectively, p = 0.132) between the groups at 2 years after stent implantation. Stent thrombosis did not occur in either group after 2 years.ConclusionsThe carvedilol-loaded stents tended to inhibit neointimal hyperplasia without the occurrence of cardiac death, myocardial infarction, or stent thrombosis at 2-year follow-up.

Influence of valsartan-eluting stent on neointima formation

Objective :—This study is to explore the effect of valsartan-eluting stents on neointima formation after stenting and to elucidate possible mechanisms how locally used valsartan prevents in-stent restenosis (ISR). METHOD: valsartan- and carriereluting stents were manufactured by using multi-layer-coated technology. Bare stents, carrier-eluting stents and valsartan– eluting stents were implanted into the abdominal aortas of the rabbits respectively. Quantitative angiography (QA) before, immediately after and 3 months after stent implantation were compared between the groups of bare (n=8), carrier-eluting (n=8) and valsartan-eluting stent (n=10), which allows the comparison of vascular diameters of aortas as well as indices of vascular neointimal formation, i.e. luminal area (LA), neointimal area (NIA), inner elastic membrane luminal area (IELA) and the maximal inner-membrane thickness (MIT) in 15 rabbits. α-Actin protein expression were detected by Envision two-step immunohistochemistry. Mean positive indices (MPI) of the above protein were analyzed semi-quantatively by IMS(Information Management System) cell image analysis system. MPI=positive area×OD (optical density). Collagen deposition in neointima was observed through MASSON stain among the three groups.Result:—the mean aortic diameters were similar in the three groups:bare stents group(n=8), carrier-eluting stents group(n=8) and valsartan eluting stents group(n=10) measured by QA at different time. A larger luminal area and a less neointimal hyperplasia in valsartan eluting-stents group was found compared with the other two groups. The mean luminal areas were 4345548±125822um2; 4302061±167952 um2; 5016269±207934um2 respectively. The mean neointimal areas were 1119635±163503um2; 1135636±136555um2; 441577±74099um2 and the mean maximal inner-membrane thickness were 210±30um;192±21um; 116±12um respectively. α-Actin protein expression was significantly lower in neointima of valsartan eluting-stents group than the other two groups. Through MASSON stain we found that Collagen was much richer in neointima of bare stents group and carrier-eluting stents group than valsartan eluting-stents group.Conclusion:—Valsartan eluting-stents inhibited neointimal hyperplasia after stenting by decreasing collagen deposition and smooth muscle cell proliferation. Therefore it would be potentially effective in preventing in-stent restenosis.Abbreviations:—Quantitative angiography (QA), luminal area (LA), neointimal area (NIA), inner elastic membrane luminal area (IELA), the maximal inner-membrane thickness (MIT), Mean positive indices (MPI), optical density (OD), Drugeluting stents (DES), in-stent restenosis(ISR), percutaneous transluminal coronary angioplasty (PTCA), angiotensin α type 2 receptor (AT2).

Passive immunization with monoclonal IgM antibodies against phosphorylcholine reduces accelerated vein graft atherosclerosis in apolipoprotein E-null mice

Phosphorylcholine (PC) headgroup is one of the neoantigens exposed by LDL oxidation that can elicit an immune response. Active immunization with Streptococcus pneumoniae, which bears PC on its cell wall, reduced atherosclerosis in hypercholesterolemic mice and this effect was attributed to an immune response to PC. In this study we tested the hypothesis that passive immunization with a monoclonal anti-PC IgM antibody can be athero-protective in a murine model of native aortic and vein graft atherosclerosis. Inferior vena cava from 16-week-old donor male apoE-null mice was grafted into right carotid artery of age-matched male recipient apoE-null mice. Anti-PC IgM titers were evaluated before and 4 weeks after surgery. For the immunization protocol, a separate group of mice received weekly intraperitoneal injection of monoclonal anti-PC IgM (400 μg) for 4 weeks, starting the day of surgery. Controls received PBS or pooled polyclonal IgM. Anti-PC IgM titres significantly increased at 4 weeks following surgery. Passive immunization with anti-PC IgM reduced vein graft plaque size and neointimal thickness resulting in a larger luminal area; in addition immunization reduced the inflammatory cell content of the plaques. There was no significant effect on the established native aortic atherosclerotic lesions. Immunization did not affect circulating cholesterol levels. Taken together our data suggest that passive immunization with anti-PC IgM significantly reduces vein graft lesion size with less inflammatory phenotype without affecting cholesterol levels, indicating an athero-protective immune response to PC. Lack of effect on established native aortic lesions may have been due to short duration of therapy and/or reduced efficacy in established lesions as compared to evolving lesions of vein graft atherosclerosis.

Carotid stenting using heparin-coated balloon-expandable stent reduces intimal hyperplasia in a baboon model

Purpose. This study evaluates the effect of heparin-coated balloon-expandable stents on intimal hyperplasia following carotid artery stenting in a baboon model. Materials and methods. Balloon-expandable (Palmaz-Schatz) stents were placed in bilateral common carotid arteries in 26 male baboons (mean weight: 11.3 kg). In each animal, a heparin-coated (HC) carotid stent was placed on one side, whereas the contralateral carotid artery received an uncoated stent that served as a control. The carotid stents were harvested at 30 days ( n = 13) and 90 days ( n = 13). Arteriography was performed to assess the carotid patency, and intravascular ultrasound was used to determine neointimal and luminal areas. Histological, morphometric analysis, and scanning electron microscopy were performed in the stented carotid arteries. Results. One animal was excluded in each of the 1-month and 3-month groups because of premature death. Ten control (83%) and 11 HC stents (92%) remained patent in the 30-day group. In contrast, 10 control (83%) and 10 HC stents (83%) remained patent in the 90-day group. Morphometric analysis of the 30-day group showed the HC-stented carotid arteries had larger luminal areas (13%, P < 0.05), less neointimal areas (38%, P < 0.05), less neointimal/media ratios (53%, P < 0.05), and equivalent medial areas (NS) when compared with the control group. Morphometric analysis of the 90-day data showed the HC-stented carotid arteries had less neointimal areas (38%, P < 0.05) and less neointimal/media ratios (48%, P < 0.05), whereas the luminal areas and medial areas remained equivalent (NS) when compared with the control group. Conclusions. Carotid stenting using heparin-coated stents reduces early intimal hyperplasia in a baboon model. This approach may represent a useful strategy for improving luminal patency in endovascular carotid intervention.

Heparin-coated Balloon-expandable Stent Reduces Intimal Hyperplasia in the Iliac Artery in Baboons

To examine the effect of heparin-coated balloon-expandable iliac stent placement on intimal hyperplasia in a baboon model. Balloon-expandable (Palmaz-Schatz) stents were placed in bilateral common iliac arteries in 20 male baboons (mean weight: 8.8 kg). In each animal, a heparin-coated iliac stent was placed on one side and the contralateral iliac artery received an uncoated stent that served as a control. The iliac artery stents were harvested at 30 days (n = 10) and 90 days (n = 10). Arteriography was performed to assess iliac patency and intravascular ultrasonography was used to determine neointimal and luminal areas. Histologic and morphometric analysis and scanning electron microscopy were performed in the stent-implanted iliac arteries. One animal was excluded in the 30-day group because of premature death. In the remaining nine surviving animals, seven control stents (78%) and nine heparin-coated stents (100%) remained patent. Morphometric analysis showed that the iliac arteries with heparin-coated stents had larger luminal areas (17%, P <.05), less neointimal area (26%, P <.05), lower neointima-to-media ratios (32%, P <.05), and equivalent medial areas (P =.92) compared to the control group at 30 days. In contrast, all control and heparin-coated stents were patent (100%) in the 90-day group. In that group, the heparin-coated stent group had less neointimal area (28%, P <.05), lower neointima-to-media ratios (42%, P <.05), and equivalent medial area (P =.92) and luminal area (P =.07) compared to the control group. The data demonstrate that heparin-coated balloon-expandable stents reduce intimal hyperplasia after iliac artery stent placement. This approach may represent a useful strategy for prolonging luminal patency after iliac stent placement.

Response to balloon injury is vascular bed specific: A consequence of de novo vessel structure?

Relative contributions of remodelling and neointimal hyperplasia to restenosis after coronary angioplasty have been inferred from studies using iliofemoral arteries, despite differences in structure/function and smooth muscle cell lineage. We compared the response to balloon overstretch injury of coronary arteries (C, n=16) and similar sized branches of the iliac arteries (I, n=18) using preinjury vessel diameter ( P), inflated balloon size in vivo ( B) and the manufacturer predicted inflated size ( M) to examine arterial compliance, as well as resulting injury and morphology in perfusion fixed vessels. Despite similar degrees of oversizing ( M/ P) in the coronary and iliac arteries (C, 1.44±0.04; I, 1.51±0.02), the compliance to overstretch ( B− P/ M− P) was significantly greater in the coronary than the iliac arteries (C, 0.71±0.05; I, 0.51±0.03) ( P<0.05) and was associated with a higher injury score (C, 1.64±0.31; I, 0.39±0.18 P<0.05)—only 5/18 iliac vessels had rupture of the IEL compared with 13/16 in the coronary bed. In a subgroup of animals whose vessels (C: n=7; I: n=8) were perfusion fixed 28 days after injury, coronary arteries had greater intimal area (C:1.03±0.42; I:0.10±0.03 mm 2, P<0.05) but larger luminal area (C:1.61±0.71; I:0.76±0.51, P<0.05) due to greater area within EEL (C:3.38±0.49;I:1.49±0.54, P<0.05) or less inward remodelling. The injuries resulting from similar strategies of balloon overstretch in the coronary and the iliac arteries are different and affect healing responses-iliac arteries remodel more while coronary arteries develop more intimal hyperplasia. These results indicate that caution is warranted when extrapolating results from the iliac to the coronary artery when investigating restenosis after angioplasty.

Reduction of Intimal Hyperplasia by Naroparcil, a 4-Methylumbelliferyl β- d -Xyloside Analogue, After Arterial Injury in the Hypercholesterolemic Rabbit

4-Methylumbelliferyl beta-D-xylosides (beta-D-xylosides) inhibit proteoglycan synthesis, and this is associated with reduced proliferation and extracellular matrix production by vascular smooth muscle cells. This study evaluated whether treatment with naroparcil, a beta-D-xyloside analogue, reduced intimal hyperplasia after arterial injury in the hypercholesterolemic rabbit. Forty-two rabbits were assigned to three groups that received either a 1% cholesterol-enriched diet (group 1, n = 15) or the same diet with added 100 mg.kg-1 naroparcil (group 2, n = 15) or 300 mg.kg-1 naroparcil (group 3, n = 12). All animals underwent iliac artery endothelial abrasion at day 14 and were killed at day 56. At the time of death, the angiographic minimal luminal diameter was significantly larger in both treated groups. Morphometric analysis showed a larger luminal area in treated rabbits (groups 2 and 3) compared with control rabbits (group 1) (0.75 +/- 0.54 and 0.85 +/- 0.61 mm2 versus 0.32 +/- 0.25 mm2, respectively; P < .05), with a decreased intimal thickness in groups 2 and 3 (average reduction of 37% and 39%, respectively, compared with group 1; P < .05) but without changes in medial area. Total vessel area was comparable among all groups. In the media, immunohistochemistry suggested reduced infiltration by macrophages and a larger fractional area of smooth muscle cells. There were no differences in plasma or arterial wall cholesterol content between groups. Plasma levels of glycosaminoglycans and dermatan sulfate content were increased only in group 3. In this model, oral treatment with naroparcil appears to preserve the arterial lumen and reduce intimal thickness after arterial injury.

Dilation of the internal mammary artery by external and intraluminal papaverine application

Three methods for prevention of perioperative spasm of the internal mammary artery were compared in 78 patients undergoing coronary artery bypass grafting. In group 1, internal mammary artery pedicles were divided distally, clamped, and placed under the upper sternum submerged in papaverine solution (1.5 mg/ml). In group 2, as in group 1 but before clamping, 2 ml of heparinized blood with 1.5 mg/ml papaverine added was injected into the vessel lumen. In group 3 treatment was as in group 2, but heparinized blood with papaverine was injected a second time just before extracorporeal bypass was begun. In a univariate analysis free flow from dilated internal mammary arteries was not significantly different among the groups (group 1, 58 ml/min; group 2, 82 ml/min; group 3, 68 ml/min; p < 0.1). When free flow from dilated internal mammary arteries was the dependent variable in a regression analysis, the use of intraluminal papaverine, high blood pressure during flow measurement, and high initial blood flow were predictors of high flow (all p < 0.01). Morphometric measurements on the resected distal portion of the dilated internal mammary arteries disclosed less folding of the internal elastic lamina and a larger luminal area in groups 2 and 3 compared with respective findings in group 1 (1.21 mm 2 and 1.42mm 2 versus 0.77 mm 2; p < 0.02). Mechanical vessel wall injury occurred in 8 of 52 internal mammary arteries treated with intraluminal papaverine. Intraluminal papaverine solution injected once or twice in addition to external papaverine exposure therefore provides a better blood flow rate and distal dilation than mere submersion in papaverine solution, but at a considerable risk of mechanical wall injury. (J T HORAC C ARDIOVASC S URG 1995;110: 697-703)

Dilation of the internal mammary artery by external papaverine application to the pedicle — an improved method

Spasm of the internal mammary artery (IMA) during coronary bypass grafting may cause inadequate graft flow and makes accurate placement of sutures difficult. In addition, IMAs with poor intraoperative flow rates are more likely to occlude. In this study three methods for spasm prevention were compared in 51 patients undergoing coronary bypass surgery. In group 1, IMA pedicles were covered with a sponge soaked with papaverine solution (0.8 mg/ml of papaverine in 0.9% saline) and left intact distally, thus allowing continuous blood flow until used for bypass. In group 2, the IMAs were divided and clamped distally and the pedicle tucked into a papaverine-soaked sponge. In group 3, the IMAs were also divided distally, clamped, and placed under the upper sternum submerged in papaverine solution (0.8 mg/ml) inside a surgical glove. Free flow from the IMA was higher in group 3 than in groups 1 and 2 (60 ml/min vs. 44 and 30, respectively, P < 0.03). Morphometric measurements disclosed a larger luminal area and less folding of the internal elastic lamina in group 3 compared with groups 1 and 2 (0.73 mm2 vs 0.33 and 0.37, respectively, P < 0.03). Submersion in papaverine solution thus provides better procurement of IMA grafts than storage of the pedicle in a papaverine-soaked sponge.

Myointimal thickening in experimental vein grafts is dependent on wall tension

This study examines the relative contributions of intraluminal pressure, blood flow, wall tension, and shear stress to the development of myointimal thickening in experimental vein grafts. To study these different hemodynamic parameters, several experimental models were created in 30 New Zealand White rabbits separated into six groups: common carotid interposition vein grafts harvested at 4 weeks (VG-4) or 12 weeks (VG-12), common carotid-linguofacial vein arteriovenous fistulas harvested at 4 weeks (AVF-4) or 12 weeks (AVF-12), AVFs with partial outflow obstruction harvested at 4 weeks (AVFobs), and combination VG-AVFs in series harvested at 4 weeks (VGAVF). Blood pressure and flow in the graft or vein were measured by use of a transducer-tipped pressure catheter and electromagnetic flow meter. At harvest, veins were perfusion-fixed and proximal, middle, and distal sections were subjected to computerized morphometric analysis. Vein grafts were characterized by a high mean pressure (VG-4, 51 +/- 4; VG-12, 62 +/- 3 mm Hg), low mean flow (VG-4, 17 +/- 1; VG-12, 16 +/- 4 ml/min), large luminal area (VG-4, 19.7 +/- 2.4; VG-12, 19.3 +/- 3.9 mm2), high wall tension (VG-4, 17.0 +/- 1.5; VG-12, 19.5 +/- 2.4 x 10(3) dyne/cm), low shear stress (VG-4, 0.75 +/- 0.13; VG-12, 0.96 +/- 0.38 dyne/cm2), and a high degree of myointimal thickening (VG-4, 5.89 +/- 0.90; VG-12, 4.72 +/- 0.83 mm2). Arteriovenous fistulas were characterized by a low mean pressure (AVF-4, 5 +/- 1, AVF-12, 6 +/- 2 mm Hg), elevated blood flow (AVF-4, 82 +/- 16; AVF-12, 82 +/- 17 ml/min), small luminal area (AVF-4, 2.43 +/- 0.58; AVF-12, 7.14 +/- 2.68), low wall tension (AVF-4, 0.62 +/- 0.19; AVF-12, 0.89 +/- 0.24 x 10(3) dyne/cm), elevated shear stress (AVF-4, 108 +/- 32; AVF-12, 71 +/- 50 dyne/cm2), and decreased myointimal area (AVF-4, 1.18 +/- 0.26; AVF-12, 1.90 +/- 0.55 mm2). The addition of outflow obstruction to AVFs (AVFobs) resulted in elevated pressure (48 +/- 2 mm Hg), decreased flow (17 +/- 4 ml/min), larger luminal area (8.71 +/- 2.31 mm2), elevated wall tension (10.3 +/- 1.7 x 10(3) dyne/cm), and a degree of myointimal thickening approaching that of vein grafts (3.79 +/- 0.66 mm2).(ABSTRACT TRUNCATED AT 400 WORDS)

Myointimal thickening in experimental vein grafts is dependent on wall tension

This study examines the relative contributions of intraluminal pressure, blood flow, wall tension, and shear stress to the development of myointimal thickening in experimental vein grafts. To study these different hemodynamic parameters, several experimental models were created in 30 New Zealand White rabbits separated into six groups: common carotid interposition vein grafts harvested at 4 weeks (VG-4) or 12 weeks (VG-12), common carotid-linguofacial vein arteriovenous fistulas harvested at 4 weeks (AVF-4) or 12 weeks (AVF-12), AVFs with partial outflow obstruction harvested at 4 weeks (AVFobs), and combination VG-AVFs in series harvested at 4 weeks (VGAVF). Blood pressure and flow in the graft or vein were measured by use of a transducer-tipped pressure catheter and electromagnetic flow meter. At harvest, veins were perfusion-fixed and proximal, middle, and distal sections were subjected to computerized morphometric analysis. Vein grafts were characterized by a high mean pressure (VG-4, 51 +/- 4; VG-12, 62 +/- 3 mm Hg), low mean flow (VG-4, 17 +/- 1; VG-12, 16 +/- 4 ml/min), large luminal area (VG-4, 19.7 +/- 2.4; VG-12, 19.3 +/- 3.9 mm2), high wall tension (VG-4, 17.0 +/- 1.5; VG-12, 19.5 +/- 2.4 x 10(3) dyne/cm), low shear stress (VG-4, 0.75 +/- 0.13; VG-12, 0.96 +/- 0.38 dyne/cm2), and a high degree of myointimal thickening (VG-4, 5.89 +/- 0.90; VG-12, 4.72 +/- 0.83 mm2). Arteriovenous fistulas were characterized by a low mean pressure (AVF-4, 5 +/- 1, AVF-12, 6 +/- 2 mm Hg), elevated blood flow (AVF-4, 82 +/- 16; AVF-12, 82 +/- 17 ml/min), small luminal area (AVF-4, 2.43 +/- 0.58; AVF-12, 7.14 +/- 2.68), low wall tension (AVF-4, 0.62 +/- 0.19; AVF-12, 0.89 +/- 0.24 x 10(3) dyne/cm), elevated shear stress (AVF-4, 108 +/- 32; AVF-12, 71 +/- 50 dyne/cm2), and decreased myointimal area (AVF-4, 1.18 +/- 0.26; AVF-12, 1.90 +/- 0.55 mm2). The addition of outflow obstruction to AVFs (AVFobs) resulted in elevated pressure (48 +/- 2 mm Hg), decreased flow (17 +/- 4 ml/min), larger luminal area (8.71 +/- 2.31 mm2), elevated wall tension (10.3 +/- 1.7 x 10(3) dyne/cm), and a degree of myointimal thickening approaching that of vein grafts (3.79 +/- 0.66 mm2).(ABSTRACT TRUNCATED AT 400 WORDS)