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Biomedical subjects

C Borst

Publications and source records attributed to C Borst.

At least 55 records · Page 3Linked to original sources
PubMed1998

Temporary luminal arteriotomy seal: II. Coronary artery bypass grafting on the beating heart.

BACKGROUND: This study assessed the feasibility of applying a temporary luminal arteriotomy seal during end-to-side coronary artery bypass grafting on the beating heart. METHODS: In 18 consecutive pigs, the left internal mammary artery was grafted to the left anterior descending coronary artery, and the arteriotomy was temporarily sealed luminally by a 200-microm-thick polyurethane seal. Endothelial denudation, medial necrosis, and intimal hyperplasia were measured quantitatively and compared with conventionally sutured anastomoses (n=4 pigs). RESULTS: Insertion and retrieval of the seal required 28+/-12 and 11+/-6 seconds, respectively. Including the arteriotomy, coronary artery occlusion was limited to about 80 seconds. The seal provided a bloodless arteriotomy in all anastomoses with unimpeded coronary artery blood flow. Endothelial denudation was limited to two thirds of the circumference of the coronary artery. No medial necrosis was found. Intimal hyperplasia at the suture line was small, although more pronounced when compared with conventionally sutured anastomoses. CONCLUSIONS: In off-pump, beating-heart coronary artery bypass grafting, the temporary luminal arteriotomy seal provided a bloodless arteriotomy with negligible obstruction to coronary artery blood flow, and with a minimum of arterial wall damage. It is conceivable that this seal may expand the indications for coronary surgical procedures without cardiopulmonary bypass.

Animals↗
PubMed1998

Off-pump coronary bypass grafting: how to use the Octopus Tissue Stabilizer.

Off-pump coronary artery bypass grafting requires immobilization of the coronary artery. A suction device (Octopus Tissue Stabilizer), attached to the epicardium and connected rigidly to the operating table rail, was used through limited and full surgical access for single-vessel and multivessel arterial revascularization, respectively. An outline for its application, as used by us to construct 122 anastomoses in 70 patients, including posterior wall grafting (in 9 patients) and sequential grafting on the anterior wall (in 17 patients), is presented.

Anastomosis, Surgical↗
PubMed1998

The atherosclerotic Yucatan animal model to study the arterial response after balloon angioplasty: the natural history of remodeling.

OBJECTIVE: Remodeling in de novo atherosclerosis and in restenosis after balloon angioplasty constitutes a change in total arterial circumference which, together with plaque growth or neointimal formation, determines the lumen of the artery. To better understand the fundamental biology of neointimal formation, remodeling and their interaction, animal studies are needed. In this study, we described in detail the methodology used and the natural history of neointimal formation and remodeling after balloon angioplasty in atherosclerotic Yucatan micropigs. METHODS AND RESULTS: Atherosclerosis was induced in 60 peripheral arteries of sixteen Yucatan micropigs by a combination of denudation and atherogenic diet. Balloon angioplasty was performed in 38 arteries, with serial intravascular ultrasound (IVUS) and quantitative angiography before and after intervention and at 2, 4, 7, 14 or 42 days follow-up. Remodeling, expressed as late media-bounded area (MBA) loss, increased progressively over time. At 42 days, late MBA loss after balloon angioplasty was significantly different compared to late MBA loss in control arteries, 2.2 +/- 1.0 versus -0.3 +/- 1.1 mm2 and p = 0.02. Late lumen loss increased over time and was highest at 42 days after balloon angioplasty (2.8 +/- 0.7 mm2). The contribution of neointimal formation to late lumen loss decreased over time and the contribution of late MBA loss to late lumen increased over time and was highest at 42 days (78%). Medial necrosis was 48% at two days after balloon angioplasty and the repopulation of the media was almost completed at seven days. CONCLUSION: Remodeling following balloon angioplasty has an early onset and progresses with neointimal formation to cause restenosis over the standard 42-day time course for Yucatan micropigs. This correlates to six months renarrowing in humans. In this model, atherosclerosis and the natural history of restenosis, both with respect to neointimal formation and remodeling, resemble the human disease quite closely.

Analysis of Variance↗
PubMed1998

Is plaque formation in the common carotid artery representative for plaque formation and luminal stenosis in other atherosclerotic peripheral arteries? A post mortem study.

The atherosclerotic carotid artery is easily accessible for non-invasive duplex investigation. The aim of the present post mortem study was to examine whether plaque accumulation and luminal stenosis in the common carotid artery is representative for atherosclerotic plaque accumulation and luminal stenosis in other peripheral arteries. A total of 3765 cross-sections were obtained at regular intervals from 240 arteries (24 individuals). Five types of peripheral arteries were investigated: common carotid, femoral, common iliac, external iliac and renal arteries. In each cross-section, the lumen area, vessel area, plaque area and maximal plaque thickness was measured. For each location, the percentage luminal stenosis and relative plaque area was calculated. Relative plaque area was defined as the percentage of the vessel area which was occupied by plaque. Weak correlations (r=0.41-0.59) were observed between percentage relative plaque area or maximal plaque thickness in the common carotid artery and percentage relative plaque area in other peripheral arteries. Neither plaque accumulation nor luminal stenosis in the common carotid artery correlated with the percentage luminal stenosis in other peripheral arteries (P > 0.05). We conclude that plaque area in the common carotid artery is weakly correlated with plaque area and not correlated with luminal stenosis in other peripheral arteries.

Aged↗
PubMed1998

Coronary artery bypass grafting without cardiopulmonary bypass using the octopus method: results in the first one hundred patients.

OBJECTIVE: Cardiopulmonary bypass and global cardiac arrest enable safe coronary artery bypass grafting but have adverse effects. In off-pump coronary bypass grafting, invasiveness is reduced, but anastomosis suturing is jeopardized by cardiac motion. Therefore the key to successful off-pump coronary bypass grafting is effective local cardiac wall stabilization. METHODS: We prospectively assessed the safety and efficacy of the Octopus tissue stabilizer (Medtronic, Inc., Minneapolis, Minn.) in the first 100 patients selected for off-pump coronary bypass via full or limited surgical access. To immobilize and expose the coronary artery, two suction paddles (-400 mm Hg), fixed to the operating table-rail by an articulating arm, stabilized the anastomosis site. RESULTS: One hundred forty-one grafts (96% arterial) were used to create 172 anastomoses (17% side-to-side), up to 4 per patient, on average 23 in the full access group (46 patients) and 1.2 in the limited access group (54 patients). Complications included conversion to cardiopulmonary bypass (2%), conversion from limited to full access (3%), myocardial infarction (4%), predischarge coronary reintervention (2%), and late coronary reintervention (1%). Median postoperative length of hospital stay was 4 days (limited access) or 5 days (full access). Rapid recovery allowed 96% of patients to resume social activities within 1 month. At the 6-month angiographic follow-up, 95% of anastomoses was patent. At the 2- to 22-month follow-up (mean, 13 months), 98 patients were in Canadian Cardiovascular Society class I and 2 patients were in class II. CONCLUSION: These results suggest that off-pump coronary artery bypass grafting with the Octopus tissue stabilizer is safe. Early clinical outcome and patency rates warrant a randomized study comparing this methods with conventional coronary bypass grafting.

Cardiopulmonary Bypass↗
PubMed1998

Relation of arterial geometry to luminal narrowing and histologic markers for plaque vulnerability: the remodeling paradox.

OBJECTIVE: To relate local arterial geometry with markers that are thought to be related to plaque rupture. BACKGROUND: Plaque rupture often occurs at sites with minor luminal stenosis and has retrospectively been characterized by colocalization of inflammatory cells. Recent studies have demonstrated that luminal narrowing is related with the mode of atherosclerotic arterial remodeling. METHODS: We obtained 1,521 cross section slices at regular intervals from 50 atherosclerotic femoral arteries. Per artery, the slices with the largest and smallest lumen area, vessel area and plaque area were selected for staining on the presence of macrophages (CD68), T-lymphocytes (CD45RO), smooth muscle cells (alpha-actin) and collagen. RESULTS: Inflammation of the cap or shoulder of the plaque was observed in 33% of all cross sections. Significantly more CD68 and CD45RO positive cells, more atheroma, less collagen and less alpha-actin positive staining was observed in cross sections with the largest plaque area and largest vessel area vs. cross sections with the smallest plaque area and smallest vessel area, respectively. No difference in the number of inflammatory cells was observed between cross sections with the largest and smallest lumen area. CONCLUSION: Intraindividually, pathohistologic markers previously reported to be related to plaque vulnerability were associated with a larger plaque area and vessel area. In addition, inflammation of the cap and shoulder of the plaque was a common finding in the atherosclerotic femoral artery.

Actins↗
PubMed1998

Shrinkage of human coronary arteries is an important determinant of de novo atherosclerotic luminal stenosis: an in vivo intravascular ultrasound study.

OBJECTIVE: To assess the occurrence of arterial remodelling types and its relation with the severity of luminal stenosis in atherosclerotic coronary arteries. PATIENTS AND METHODS: Twenty one de novo coronary lesions of 20 patients, who were scheduled for percutaneous transluminal coronary angioplasty (PTCA), were investigated with intravascular ultrasound before PTCA. Local arterial remodelling at the lesion site was studied by measuring the cross sectional area circumscribed by the external elastic lamina (EEL) relative to the reference site: (EEL area lesion/reference EEL area) x 100%. Three groups were defined. Group A: relative EEL area of less than 95% (shrinkage), group B: relative EEL area between 95% and 105% (no remodelling), group C: relative increase in EEL area of more than 105% (compensatory enlargement). RESULTS: All three types of remodelling were observed at the lesion site: group A (shrinkage) n = 8, group B (no remodelling) n = 5, group C (compensatory enlargement) n = 8. The mean (SD) relative EEL area at the lesion site in group A and C was 83(9)% and 132(30)%, respectively. In group A, 33% of the luminal area stenosis at the lesion site was caused by shrinkage of the artery. In contrast, group C showed that 87% of the plaque area did not contribute to luminal area stenosis because of compensatory arterial enlargement. CONCLUSIONS: These results show that both compensatory enlargement and paradoxical shrinkage occurs in the atherosclerotic coronary artery. Next to plaque accumulation, the type of atherosclerotic remodelling is an important determinant of luminal narrowing.

Adult↗
PubMed1998

The relation between de novo atherosclerosis remodeling and angioplasty-induced remodeling in an atherosclerotic Yucatan micropig model.

Geometric remodeling in de novo atherosclerosis and in restenosis after balloon angioplasty constitutes a change in total arterial circumference that, together with plaque growth or neointima formation, determines the lumen of the artery. The heterogeneous nature of arterial obstructions raises the question of whether early and late outcomes (restenosis) of angioplasty are affected by the degree and direction of de novo atherosclerotic remodeling. This study was designed to assess the relationship between atherosclerotic remodeling and the degree and mechanism of restenosis after balloon angioplasty. Atherosclerosis was induced in 27 peripheral arteries of 18 Yucatan micropigs by a combination of denudation and atherogenic diet. Balloon angioplasty was performed, with serial intravascular ultrasound and quantitative angiography before and after intervention and at 42 days' follow-up. We used the relative media-bounded area (MBA), defined as the MBA of the treated site divided by the MBA of the reference, before angioplasty as a measure of remodeling in de novo atherosclerosis and late MBA loss as a measure of remodeling after balloon angioplasty. Relative MBA before angioplasty was not correlated with angiographic and echographic acute gain after balloon angioplasty (r=.22, P=.28 and r=.14, P=.48) or with late lumen loss (r=-.05, P=.81 and r=.19, P=.33). No correlation was found between relative MBA and late MBA loss (r=.14 and P=.48). In the atherosclerotic Yucatan micropig, remodeling during de novo atherosclerosis has no relevance for acute gain and late lumen loss after balloon angioplasty. Both the direction and the extent of remodeling after balloon angioplasty are not related to the direction and extent of remodeling during de novo atherosclerosis.

Angiography↗
PubMed1998

Shear stress in atherosclerosis, and vascular remodelling.

Shear stress plays a role in lipid accumulation in primary atherosclerosis and vascular remodelling. We will present applications of a new technique, which enables to quantify shear stress in 3D vessel reconstructions. The method is based on 3D IVUS reconstructions of blood vessels either obtained by IVUS pull back (external iliac artery) or by a combination of angiography and IVUS (curved coronary artery). Distribution of wall thickness of a curved human right coronary artery was such that low wall thickness occurred where shear stress was high, and wall thickness was high where shear stress was low. Consequently, an inverse relationship between shear stress and wall thickness was detected. Although vascular remodelling after PTA in external iliac arteries of atherosclerotic Yucatan pigs was predicted both by acute gain and decrements in shear stress, the decrement in shear stress appeared a better predictor. In conclusion, shear stress appears to play a role in primary atherosclerosis and vascular remodelling after PTA.

Adaptation, Physiological↗
PubMed1997

Arterial remodeling after balloon angioplasty or stenting in an atherosclerotic experimental model.

BACKGROUND: Recent studies have indicated that coronary restenosis after balloon angioplasty is the sum of geometric remodeling and neointimal formation. A proportional relationship between acute gain and late lumen loss has been observed in clinical trials. The aims of this study were to evaluate (1) the contribution of geometric remodeling and neointimal formation to the proportional gain-loss relationship after PTA or stenting and (2) the relationship between geometric remodeling and neointimal formation. METHODS AND RESULTS: In atherosclerotic iliac arteries of 29 Yucatan micropigs, PTA or stenting was performed, with serial intravascular ultrasound (IVUS) and quantitative angiography before and after intervention and at 2 or 42 days of follow-up, followed by histomorphometrical analysis. For PTA at 42 days, late lumen loss by IVUS correlated strongly with geometric remodeling, expressed as late media-bounded area (MBA) loss (R2=.843, P<.001, n=20), and correlated weakly with intimal hyperplasia area (R2=.214, P=.02). For stented arteries, however, late lumen loss correlated moderately with intimal hyperplasia (R2=.367, P=.01, n=18) and only weakly with geometric remodeling (R2=.195, P=.04). Late lumen loss and late MBA loss of reference segments were observed at 42 days, especially in PTA arteries. Intimal hyperplasia and geometric remodeling were not correlated. CONCLUSIONS: In this experimental model, the proportional relationship between acute gain and late lumen loss is mainly due to the proportional relationship between acute gain and geometric remodeling for PTA and between acute gain and intimal hyperplasia for stents. Finally, neointimal formation and remodeling seem to be unrelated processes.

Angiography↗
PubMed1997

[Minimally invasive arterial coronary bypass grafting: on beating heart and via smaller access].

Postoperative recovery after (arterial) coronary bypass grafting mostly takes several months because of the effects of the heart-lung machine and the cardioplegia which are mostly haematological, pneumological and neurological in nature. The morbidity can be reduced by operating on the beating heart and via smaller access. One possibility is the 'Octopus' method developed in Utrecht, which involves local fixation of the beating heart. The postoperative recovery of the first 45 patients was favourable.

Anastomosis, Surgical↗
PubMed1997

Prediction of restenosis after coronary balloon angioplasty. Results of PICTURE (Post-IntraCoronary Treatment Ultrasound Result Evaluation), a prospective multicenter intracoronary ultrasound imaging study.

BACKGROUND: Intracoronary ultrasound (ICUS) imaging is potentially suitable to identify lesions at high risk of restenosis after percutaneous transluminal coronary angioplasty (PTCA), but it has not been studied systematically. METHODS AND RESULTS: We recruited 200 patients in whom ICUS studies were performed after successful PTCA and related their ICUS parameters to 6-month follow-up quantitative coronary angiography. This was performed in 164 patients (82%), yielding 170 lesions for analysis. The overall incidence of a > or = 50% diameter stenosis at follow-up (categorical restenosis) was 29.4%. Quantitative ICUS parameters were weakly but significantly related to follow-up minimal luminal diameter on quantitative coronary angiography (lumen area: R2 = .36, P = .0001; vessel area: R2 = .29, P = .0002; plaque area: R2 = -.18, P = .021; percent obstruction: R2 = -.15, P = .05), but categorical restenosis was not significantly related to these parameters (P = .63, .77, .38, and .08, respectively). There were no significant predictors of restenosis in ICUS parameters of plaque morphology: eccentric versus concentric (P = 1.0), plaque type (hard, soft, or calcific, P = .98), or the number of calcified quadrants (P = .41). There were no significant predictors of restenosis in two predefined types of vessel-wall disruptions: (1) rupture: presence (P = .79), depth (partial versus complete, P = .85), or extent in quadrants (P = .6), and (2) dissection: presence (P = .31), depth (P = .82), or extent (P = .38). CONCLUSIONS: Qualitative ICUS parameters after PTCA did not predict restenosis. A larger lumen and vessel area and a smaller plaque area by ICUS were associated with a larger angiographic minimal lumen diameter at follow-up, but these parameters were not significantly related to categorical restenosis.

Aged↗
PubMed1997

Impact of local atherosclerotic remodeling on the calculation of percent luminal narrowing.

The choice of the reference site in order to calculate percent luminal narrowing mainly depends on which diagnostic tool is used for examination. In intravascular ultrasound or histology, the local area encompassed by the internal elastic lamina (IEL) area is used as a reference. However, the local IEL area, and thereby the reference value, may have been altered by atherosclerotic remodeling. In the present study we examined the impact of local arterial remodeling on the calculation of luminal narrowing. Forty-five human femoral arteries were analyzed, 32 postmortem and 20 in vivo, by intravascular ultrasound. Cross sections were examined every 0.5 cm over an arterial segment length of 10 to 15 cm. In each cross section we measured the lumen area and the IEL area. Two reference areas were used to calculate percent luminal narrowing: (1) the lumen area in the cross section that contained the least amount of plaque (distant reference); and (2) the local IEL area (local reference). In each cross section, the IEL area was expressed as percent of the IEL area in the cross section that contained the least amount of plaque (relative IEL area). Using the distant reference, we found that less luminal narrowing was observed for cross sections with a relative IEL area > 100% (indicating compensatory enlargement) than for those with a relative IEL area < 100% (indicating shrinkage), whereas percent luminal narrowing calculated using the local reference hardly differed between cross section with a relative IEL area > 100% and < 100%. Thus, arterial wall remodeling makes the local IEL area an unreliable reference for calculation of percent luminal narrowing. The calculated percent luminal narrowing using a distant, nondiseased reference site reflects the actual change of the luminal area more accurately.

Aged↗
PubMed1997

Arterial remodeling after balloon angioplasty of the coronary artery: an intravascular ultrasound study. PICTURE Investigators. PostTreatment IntraCoronary Transluminal Ultrasound Result Evaluation.

OBJECTIVE: Before balloon dilation, failure of compensatory enlargement and even arterial shrinkage are frequently observed at the lesion site in response to plaque accumulation. Balloon angioplasty may be regarded as artificial remodeling to enlarge the artery. The prevalence of the different types of arterial wall remodeling after applied stretch by balloon angioplasty is unknown. METHODS AND RESULTS: In 181 patients an intravascular ultrasound study was performed after coronary balloon angioplasty (n = 200 lesions). The vessel area was measured at a proximal and distal reference site and at the lesion site. Subsequently, the relative vessel area [(Vessel area lesion site)/Vessel area reference site) x 100] was calculated. Lesions were classified in three groups on the basis of their relative vessel areas: > or =105%, <105% but >95%, and < or =95%. A relative vessel area > or =105%, indicating enlargement compared with the reference site, was observed in 84 (44%) lesions. A relative vessel area <105% but >95% was observed in 43 (22%) lesions. A relative vessel area < or =95%, indicating "shrinkage" compared with the reference site, was observed in 66 (34%) lesions. CONCLUSIONS: After balloon angioplasty, the vessel area was found to be smaller compared with the reference site in 34% of the lesions. This small vessel area at the lesion site compared with a reference site may be a reflection of insufficient stretch by balloon angioplasty.

Angioplasty, Balloon, Coronary↗
PubMed1997

Hemodynamic changes during displacement of the beating heart by the Utrecht Octopus method.

BACKGROUND: Coronary bypass grafting of posterior circumflex branches requires full displacement of the heart (apex pointing ventrally), which, in the beating heart, results in an arterial pressure drop. We analyzed its origin. METHODS: To facilitate displacement, the Utrecht "Octopus" method was applied in 8 anesthetized beta-blocked pigs and the beating heart was fully retracted. RESULTS: Displacement decreased stroke volume from 75 +/- 17 mL (mean +/- standard deviation) to 43 +/- 13 mL (p < 0.001), a 44% +/- 3% decrease that resulted in a decrease in cardiac output by 32% +/- 5% (mean +/- standard error of the mean; p < 0.001), a decrease in mean arterial pressure by 26% +/- 5% (p < 0.01), and an increase in heart rate by 26% +/- 6% (p < 0.01). Right ventricular end-diastolic pressure increased from 5 +/- 1 to 8 +/- 1 mm Hg (p < 0.01). Twenty degrees head-down tilt normalized cardiac output and mean arterial pressure. Right ventricular end-diastolic pressure increased to 10 +/- 2 mm Hg (p < 0.001) and left ventricular end-diastolic pressure to 11 +/- 3 mm Hg (p < 0.01). CONCLUSIONS: Displacement of the beating heart in the pig induced a 44% drop in stroke volume, which is attributed to biventricular interference with pump function. The Trendelenburg maneuver reestablished the control circulatory status at the expense of augmented right and left ventricular preloads and an increased heart rate.

Animals↗
PubMed1997

Experimental off-pump grafting of a circumflex branch via sternotomy using a suction device.

BACKGROUND: We have shown previously in the pig that coronary artery bypass grafting on the beating heart may be facilitated by local cardiac wall immobilization by a suction device ("Octopus") applied to the anterolateral side of the heart. The purpose of this study was to investigate the feasibility of the method on the posterolateral side. METHODS: In a consecutive series of 8 pigs, after median sternotomy, the posterior wall was taken hold of by the Octopus and subsequently brought up anteriorly and immobilized while hemodynamics were monitored. A posterolateral branch of the circumflex artery was grafted with the left internal mammary artery. After the coronary artery was ligated proximally, the heart was repositioned. At 6 weeks, bypass graft angiography and functional testing (postocclusion hyperemia testing) were performed. After sacrifice, histologic examination of the anastomosis was performed. RESULTS: Dislocation of the heart to expose the distal anastomosis site caused a minor drop in mean arterial blood pressure from 71 +/- 14 (baseline) to 63 +/- 6 mm Hg (dislocated) (not significant) and recovery to 70 +/- 12 mm Hg, 15 minutes after repositioning. Cardiac output decreased from 4.0 +/- 1.0 to 3.2 +/- 0.7 L/min (p = 0.02) and recovered to 4.3 +/- 0.3 L/min. No inotropic drugs were necessary. Anastomosing required 21.5 +/- 6.5 minutes. Baseline graft flow was 8 +/- 3 mL/min and increased threefold to 24 +/- 10 mL/min (p < 0.05) at postocclusive hyperemia testing. At sacrifice after 6 weeks (n = 8), graft flow increased fourfold from 5 +/- 2 to 20 +/- 8 mL/min (p = 0.002) (n = 7). At histologic examination all eight anastomoses were patent without stenosis or mural thrombus. CONCLUSIONS: Off-pump coronary artery bypass grafting of the posterolateral circumflex branches using the Octopus method on the beating pig heart is feasible, with full patency maintained for at least 6 weeks.

Anastomosis, Surgical↗
PubMed1997

Minimally invasive coronary artery bypass grafting: on the beating heart and via limited access.

Minimally invasive coronary artery bypass grafting (MICABG) may be achieved by arterial grafting on the beating heart, without cardiopulmonary bypass, and by operations via limited access. The Second Utrecht MICABG Workshop held October 4-5, 1996, focused on beating-heart coronary immobilization, limited-access thoracoscopic and direct-vision mobilization of the internal mammary artery, limited-access left anterior descending coronary artery grafting, and, finally, facilitated distal anastomosis techniques. It has yielded 33 reports in this supplement. The combined, cumulative experience of a number of participants exceeded 3,000 beating-heart cases, including more than 1,000 with arterial grafting through limited access. The average number of anastomoses per patient ranged from 1.0 to 2.0. Therapeutic strategies are evolving, and dedicated instrumentation is being developed. Randomized clinical trials with angiographic follow-up are required to establish that the reduction in invasiveness of coronary bypass grafting is not achieved at the expense of suboptimal quality of the arterial graft and the distal anastomosis.

Cardiopulmonary Bypass↗