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Biomedical subjects

C Borst

Publications and source records attributed to C Borst.

At least 37 records · Page 2Linked to original sources
PubMed2000

The Octopus Study: rationale and design of two randomized trials on medical effectiveness, safety, and cost-effectiveness of bypass surgery on the beating heart.

The Octopus Study consists of two multicenter randomized clinical trials in which coronary artery bypass grafting on the beating heart (off-pump CABG) using the Utrecht Octopus Method is compared to intracoronary stent implantation and conventional CABG. The primary endpoint in the comparison of off-pump CABG versus stent implantation (OctoStent Trial) is medical effectiveness (i.e., absence of reintervention and major adverse cardiac and cerebrovascular events at 1 year after treatment). The primary endpoint in the comparison of off-pump CABG versus conventional CABG (OctoPump Trial) is cerebral safety (i.e., absence of cognitive deficits and cerebrovascular events at 3 months after treatment). Secondary endpoints in both trials include presence and severity of angina, quality of life, exercise capacity, and cost-effectiveness. A total of 560 patients will be enrolled. A random sample of 210 patients will undergo repeat angiography at 1 year to assess angiographic restenosis rate and graft patency. Including 1-year follow-up, the study will last for 3 years. Control Clin Trials 2000;21:595-609

Angioplasty, Balloon, Coronary↗
PubMed2000

Techniques characterizing the coronary atherosclerotic plaque: influence on clinical decision making?

The composition of the atherosclerotic lesion rather than the degree of stenosis is currently considered to be the most important determinant for acute clinical events. Modalities capable of characterizing the atherosclerotic lesion may be helpful in understanding its natural history and detecting lesions with high risk for acute events. Speaking grossly, three histologic features of the vulnerable plaque have been reported: size of the atheroma, thickness of the fibrous cap, and inflammation. Imaging techniques are currently being deployed and are under development to aid visualization of the vulnerable coronary plaque. Most of these diagnostic modalities have the potential to detect locally one or more of the three histologically defined features of vulnerable plaque. This review will focus on imaging techniques that have been developed to characterize the atherosclerotic lesion. Most catheter-based visualization techniques will provide insight into components of the local atherosclerotic plaque which may limit their predictive value for the occurrence of a clinical event. Therefore, the clinical relevance of these imaging tools will be discussed.

Coronary Artery Disease↗
PubMed1999

Temporary luminal arteriotomy seal: III. Postmortem arteriosclerotic human coronary artery.

BACKGROUND: Recently, we described a temporary luminal arteriotomy seal that provided a bloodless arteriotomy without obstructing recipient artery blood flow during bypass grafting in nonarteriosclerotic porcine arteries. This postmortem study assessed the sealing properties in irregular arteriosclerotic human coronary arteries. METHODS: Three hearts were obtained from donated corpses within 24 hours of death. The coronary arteries were pressure-perfused at 60 mm Hg with citrated porcine blood. At 15 anastomosis sites in four different coronary arteries, an end-to-side anastomosis was created using a 200-microm-thick polyurethane seal. Adequacy of sealing was determined at perfusion pressures of 60, 40, and 20 mm Hg. RESULTS: After insertion, the arteriotomy was sealed instantaneously in 10 of 15 anastomoses. After repositioning, complete sealing with a bloodless operative field was obtained in all cases. Low intracoronary transmural pressure did not impede sealing. In 8 of 15 anastomoses, minor leakage without obscuring the arteriotomy edges was observed during anastomotic suturing. Histologic examination revealed no intimal tear or dissection caused by the anastomotic procedure. CONCLUSIONS: In postmortem-obtained arteriosclerotic human coronary arteries, the temporary luminal arteriotomy seal provided optimal visualization of the coronary anastomosis site in combination with persistent distal perfusion.

Aged↗
PubMed1999

Angioscopic complex lesions are predominantly compensatory enlarged: an angioscopy and intracoronary ultrasound study.

OBJECTIVES: Atherosclerotic remodeling of the coronary artery may lead to compensatory enlargement or to shrinkage. Post-mortem data suggest a relation between compensatory enlargement and histopathological markers of plaque vulnerability. In patients that required a coronary intervention, we investigated retrospectively the relation between the angioscopic appearance and the remodeling mode of the culprit lesion. METHODS: In 34 patients, coronary angioscopy and intracoronary ultrasound (ICUS) imaging was performed across the culprit lesion before the intervention. Only single de novo lesions were included. With angioscopy, lesions with a smooth surface without thrombus were classified as smooth, whereas lesions with an irregular surface with or without thrombus were classified as complex. With ICUS, remodeling of the culprit lesions was determined by the relative cross-sectional vessel area (lesion vessel area/reference vessel area) x 100%. Lesions were divided into three groups: compensatory enlargement (relative vessel area > or = 105%), no-remodeling (relative vessel area between 95 and 105%) and shrinkage (relative vessel area < or = 95%). RESULTS: In 22 patients good images were obtained with both imaging modalities. More complex lesions were compensatory enlarged compared to shrunken lesions, whereas more smooth lesions were shrunken compared to compensatory enlarged lesions, 8/9 versus 2/7 and 5/7 versus 1/9, respectively (p = 0.035). CONCLUSIONS: In patients selected for coronary intervention, angioscopic complex atherosclerotic lesions were found predominantly in compensatory enlarged arterial segments, whereas smooth lesions were found predominantly in shrunken arterial segments.

Adult↗
PubMed1999

Exposure of circumflex branches in the tilted, beating porcine heart: echocardiographic evidence of right ventricular deformation and the effect of right or left heart bypass.

OBJECTIVE: In off-pump coronary surgery, exposure of posterior vessels via sternotomy causes deterioration of cardiac function. Changes in ventricular geometry, valve competence, and hemodynamics after retraction of the beating heart were studied. Subsequently, the modifying effect of right or left heart bypass was investigated. METHODS: In six 80-kg pigs, an ultrasound probe was attached to the backside of the left ventricle and the heart was fully retracted with a suction tissue stabilizer. Five pigs underwent additional pump support. RESULTS: During retraction, the right ventricle was squeezed between the pericardium and interventricular septum, thereby decreasing its diastolic cross-sectional area by 62% +/- 6% (P <.001) while, concomitantly, right ventricular end-diastolic pressure increased to 165% +/- 19% (P =.004) of basal values. Stroke volume and mean arterial pressure decreased by 29% +/- 6% and 23% +/- 8% (P =.007 and P =.02, respectively). Left ventricular shape became somewhat elliptic without changes in preload pressure, and its diastolic cross-sectional area decreased by 20% +/- 3% (P =.001). All valves were competent. Right heart bypass restored left ventricular cross-sectional area, stroke volume, and mean arterial pressure. In contrast, left heart bypass increased blood pressure only marginally. CONCLUSIONS: Ninety-degree anterior displacement of the beating porcine heart caused primarily right ventricular dysfunction as a result of mechanical interference with diastolic expansion without concurring valvular incompetence. Right heart bypass normalized stroke volume and mean arterial pressure by increasing left ventricular preload; in contrast, left heart bypass failed to restore systemic circulation.

Animals↗
PubMed1999

A novel one-shot anastomotic stapler prototype for coronary bypass grafting on the beating heart: feasibility in the pig.

OBJECTIVE: The nonpenetrating, arcuate-legged clip has proved its ability to provide a high-quality microvascular anastomosis. This study assessed the feasibility of constructing a coronary end-to-side anastomosis on the beating heart with a novel mechanical, sutureless anastomotic device that applies 12 circumferential clips simultaneously. METHODS: In 14 consecutive pigs (70-90 kg), the left internal thoracic artery (diameter, 3 mm) was grafted to the left anterior descending coronary artery (diameter, 3 mm) by means of a one-shot anastomotic stapler prototype. Endothelial denudation, medial necrosis, and intimal hyperplasia were analyzed quantitatively and compared with those seen in conventionally sutured anastomoses (n = 4). RESULTS: In 8 of 14 anastomoses, the one-shot anastomotic stapler successfully applied all 12 clips circumferentially across the everted arteriotomy edges. In the remaining, either 1 (n = 4) or 3 and 4 adjoining malaligned clips had to be replaced manually with a single-clip applicator. Coronary occlusion was limited to approximately 3 minutes. At follow-up, all anastomoses were patent angiographically. At 2 days, in 2 of 7 cases, a local coronary dissection was observed, and there was a considerable loss of endothelial cells and medial damage. At 28 days, however, minimal intimal hyperplasia was seen at the anastomotic lining, although more pronounced when compared with conventionally sutured anastomoses. CONCLUSIONS: The one-shot anastomotic stapler prototype enabled short-occlusive (3 minutes), sutureless end-to-side grafting on the beating porcine heart. In spite of early endothelial and medial damage and 2 local dissections, all anastomoses remained patent with minimal intimal hyperplasia at 4 weeks.

Anastomosis, Surgical↗
PubMed1999

Clinical implications of online and off-line interobserver variability in intracoronary ultrasound-guided interventions.

UNLABELLED: Intracoronary ultrasound (ICUS)-guided interventions imply online decision making. We investigated the on- and off-line interobserver variability in ICUS measurements and evaluated the clinical implication of the interobserver variability for ICUS-guided interventions in 40 lesions (38 patients). On the same recorded ICUS images, an online and an off-line observer independently selected and analyzed the proximal and distal reference images, the most severe stenosis image before intervention and the minimal lumen area (MLA) image after intervention. In addition, the off-line observer analyzed the online selected images. The interobserver variability (percentage difference between the two observers) of ICUS measurements was determined on images independently selected by both observers (Analysis A) and on images selected by the online observer (Analysis B). The balloon size was determined from ICUS measurements according to the CLOUT trial. After intervention, the CLOUT and MUSIC criteria for MLA by ICUS had to be fulfilled for PTCA and stent procedures, respectively. In Analysis A, the on- and off-line interobserver variability in diameter and area measurements was maximally 9% and 18%, respectively. In Analysis B, the on- and off-line interobserver variability was maximally 6% and 11%, respectively. The off-line observer would have chosen a balloon size differing by more than 0.25 mm in 25 % (10 of 40) and 12.5% (5 of 40) of the procedures in Analysis A and B, respectively. After PTCA or stenting, the off-line observer would have taken different procedural decisions in 19% or 15% and in 13% or 7% of the procedures in Analysis A and B, respectively. IN CONCLUSION: when the same location was selected, the on- and off-line interobserver variability was low. When different locations were selected, however, the interobserver variability resulted in different balloon sizing in 25 % of the cases. Interobserver variability may be a confounding factor in the analysis of ICUS-guided interventions.

Angioplasty, Balloon, Coronary↗
PubMed1999

Embracing the heart: perioperative management of patients undergoing off-pump coronary artery bypass grafting using the octopus tissue stabilizer.

OBJECTIVE: To describe hemodynamic alterations during coronary artery bypass grafting (CABG) without extracorporeal circulation using the Octopus Tissue Stabilizer, and to describe the two anesthetic management protocols based on either general anesthesia with opioids (34 patients) or general anesthesia with high thoracic epidural anesthesia (TEA; 66 patients). DESIGN: A prospective observational report. SETTING: An academic university heart center. PARTICIPANTS: First 100 patients undergoing CABG using the Octopus Tissue Stabilizer. INTERVENTIONS: None. MAIN RESULTS: Current management provided satisfactory results in preventing hypoperfusion of the heart and inadequate systemic circulation without the use of major pharmacologic interventions. Movement of the heart to reach the target site of anastomosis caused hemodynamic alterations. These could easily be corrected by anesthetic interventions, such as fluid load and low doses of inotropes. High TEA allows earlier extubation compared with the opioid anesthesia technique (0.9 v 4.5 hours). Perioperative management and the incidence of postoperative complications did not differ between anesthetic techniques. Major complications, such as death, intraoperative myocardial infarction, and stroke, did not occur. CONCLUSION: Both anesthetic protocols are safe and effective in handling these patients. Off-pump CABG surgery requires anesthetic interventions because hemodynamic alterations are caused by the presentation of the heart to the surgeon. The complication rate is low but needs to be evaluated, compared with conventional CABG, in a prospective randomized study. High thoracic epidural anesthesia allows early recovery, but improved outcome could not be proved in this patient group.

Adjuvants, Anesthesia↗
PubMed1999

Coronary artery disease: arterial remodelling and clinical presentation.

OBJECTIVE: To investigate the hypothesis that in coronary artery disease large plaques in compensatorily enlarged segments are associated with acute coronary syndromes, whereas smaller plaques in shrunken segments are associated with stable angina pectoris. METHODS: Patients selected for percutaneous transluminal coronary angioplasty (PTCA) were divided into two groups, one with stable angina pectoris (stable group, n = 37) and one with unstable angina or postmyocardial infarction angina of the infarct related artery (unstable group, n = 32). In both groups, remodelling at the culprit lesion site was determined by intravascular ultrasound before the intervention. Remodelling was calculated as relative vessel area: [vessel area culprit lesion site / mean vessel area of both proximal and distal reference sites] x 100%. Compensatory enlargement was defined as remodelling of >/= 105%, whereas shrinkage was defined as remodelling of </= 95%. RESULTS: In the unstable group, the vessel area at the culprit lesion site was larger than in the stable group, at mean (SD) 18.1 (5.3) v 14.6 (5.4) mm(2) (p = 0.008). Lumen areas were similar. Consequently, plaque area and percentage remodelling were larger in the unstable group than in the stable group: mean (SD) 14.8 (4.8) v 11.6 (4.9) mm(2) (p = 0.009) and 112 (31)% v 95 (17)% (p = 0.005), respectively. Significantly more culprit lesion sites were classified as shrunken in the stable group (21/37) than in the unstable group (8/32; p = 0.014). On the other hand, more lesion sites were classified as enlarged in the unstable group (16/23) than in the stable group (8/37; p = 0.022). CONCLUSIONS: In patients selected for PTCA, the mode of remodelling is related to clinical presentation.

Angina Pectoris↗
PubMed1999

Inflammation of the atherosclerotic cap and shoulder of the plaque is a common and locally observed feature in unruptured plaques of femoral and coronary arteries.

-Retrospectively, plaque rupture is often colocalized with inflammation of the cap and shoulder of the atherosclerotic plaque. Local inflammation is therefore considered a potential marker for plaque vulnerability. However, high specificity of inflammation for plaque rupture is a requisite for application of inflammation markers to detect rupture-prone lesions. The objective of the present study was to investigate the prevalence and distribution (local versus general) of inflammatory cells in nonruptured atherosclerotic plaques. The cap and shoulder of the plaque were stained for the presence of macrophages and T lymphocytes in 282 and 262 cross sections obtained from 74 coronary and 50 femoral arteries, respectively. From most cases, 2 atherosclerotic arteries were studied to gain insight into the local and systemic distribution of the inflammatory process. In 45% and 41% of all cross sections, staining for macrophages was observed in the femoral and coronary arteries, respectively. Rupture of the fibrous cap was observed in 2 femoral and 3 coronary artery segments and was always colocalized with inflammatory cells. At least 1 cross section stained positively for CD68 or acid phosphatase in 84% and 71% of all femoral and coronary arteries, respectively. Only 1 femoral and 6 coronary arteries revealed a positive stain for CD68 in all investigated segments. Inflammation of the cap and shoulder of the plaque is a common feature, locally observed, in atherosclerotic femoral and coronary arteries. The high prevalence of local inflammatory responses should be considered if they are used as a diagnostic target to detect vulnerable, rupture-prone lesions.

Acid Phosphatase↗
PubMed1998

Saline flush during excimer laser angioplasty: short and long term effects in the rabbit femoral artery.

BACKGROUND AND OBJECTIVE: In this study, the effect of flushing saline on arterial wall damage (medial ruptures and necrosis), intimal hyperplasia, and arterial remodeling was determined. During excimer laser coronary angioplasty saline is flushed to reduce the size of explosive water vapor bubbles formed by intraluminal delivery of excimer laser pulses in blood. METHODS: In the femoral artery of the rabbit, 600 excimer laser pulses (308 nm, 50 mJ/mm2 per pulse, 20 Hz) were delivered coaxially over a length of 20 mm in 10 bursts of 3 seconds each. In 24/48 procedures, saline was flushed (0.2 ml/s) via the guidewire channel. After 2 and 56 days, microscopic and angiographic results were compared. RESULTS: At 2 days, as compared to lasing in blood, saline flush had drastically reduced the incidence of dissections (2/12 vs. 11/12, P < 0.002), but had increased the extent of medial and adventitial necrosis. The latter is attributed to direct irradiation of the arterial wall. After 56 days, in the saline group, in the middle-distal part of treated segments, medial necrosis without intimal hyperplasia was observed. However, at the edges of these lesions, intimal hyperplasia and arterial shrinkage reduced the lumen. CONCLUSION: Flushing saline during coaxial excimer laser pulse delivery significantly reduced the incidence of vessel wall ruptures, and prevented intimal hyperplasia formation in part of the lesion. The histologic findings at 56 days are attributed to the optical window which the saline flush provides for direct ultraviolet light irradiation of the arterial wall.

Angiography↗
PubMed1998

Psoralen and long wavelength ultraviolet radiation as an adjuvant therapy for prevention of intimal hyperplasia and constrictive remodeling after balloon dilation: a study in the rabbit iliac artery.

BACKGROUND AND OBJECTIVE: Restenosis after balloon angioplasty is the summated effect of intimal hyperplasia and arterial shrinkage, both caused by hyperproliferation. In the present study, the potential of a photochemotherapeutic modality (Psoralen + UVA: PUVA) for the prevention of angioplasty induced proliferation was explored. STUDY DESIGN/MATERIALS AND METHODS: In rabbit iliac arteries, balloon dilation followed by PUVA-therapy (H = 1 J/cm2) was performed (n = 15). Contralateral arteries served as control. After 2 and 28 days of survival, the contribution of intimal hyperplasia and remodeling to lumen loss was determined by means of angiography and histological analysis. RESULTS: After 2 days, large parts of the media had become acellular, while proliferation was occurring predominantly in the adventitia in both groups. After 28 days, late loss, arterial shrinkage, but not intimal hyperplasia were larger in the PUVA group (P < 0.05). CONCLUSION: PUVA-therapy did not prevent intimal hyperplasia following balloon dilation but enhanced luminal narrowing by augmented constrictive remodeling.

Analysis of Variance↗
PubMed1998

Intima-adventitia apposition in end-to-side arterial anastomosis: an experimental study in the pig.

BACKGROUND: To prevent ischemic complications during coronary bypass grafting on the beating heart, a nonocclusive distal anastomosis technique is needed. One recently developed nonocclusive technique requires apposition of the intima of the graft to the adventitia of the recipient artery, in contrast to current surgical practice, which dictates apposition of both intimas. METHODS: To compare the sole effect of intima-adventitia apposition (n = 18) versus traditional intima-intima apposition (n = 18), we investigated radiolabeled platelet deposition and histomorphologic aspects of vascular wall healing quantitatively in a porcine carotid artery bypass graft model. Both groups were evaluated at 2 hours, 2 days, or 4 weeks. RESULTS: Within the first 2 hours, 3 of 6 pigs with intima-adventitia apposition exhibited cyclic flow reductions as a result of massive mural thrombosis. After intima-adventitia apposition, the number of deposited platelets was significantly higher compared with intima-intima apposition, 147.1 +/- 73.0 x 10(6) and 4.6 +/- 1.0 x 10(6) platelets/cm2 (mean +/- standard error of the mean), respectively (p = 0.03). At 2 days, the suture line was covered with small mural thrombi, whereas no thrombi were found after intima-intima apposition. At 4 weeks, intimal hyperplasia at heel and toe was not significantly different from that with intima-intima apposition. CONCLUSIONS: Despite thrombotic phenomena in the early phase, intima-adventitia apposition yielded a patent anastomosis with a small intimal hyperplasia response.

Anastomosis, Surgical↗
PubMed1998

Temporary luminal arteriotomy seal for bypass grafting.

BACKGROUND: To enable off-pump coronary operations in a bloodless surgical field without ischemic complications, we developed and assessed a temporary luminal arteriotomy seal in a porcine carotid artery bypass graft model. METHODS: In 16 consecutive pigs (25 kg, 32 anastomoses) the arteriotomy was sealed luminally by a polyurethane elliptic convex seal. Endothelial denudation, medial necrosis, and intimal hyperplasia were measured quantitatively and compared with those seen in conventionally sutured anastomoses. RESULTS: The median occlusive time upon insertion or retrieval was 90 and 82 seconds, including the arteriotomy and securing the anastomosis, respectively. Once properly positioned, the seal provided a bloodless arteriotomy in all anastomoses. Microsurgical suturing was performed without leakage of the seal and with unimpeded flow. In the recipient artery, endothelial denudation was limited to one third of its circumference. No medial necrosis was found. Intimal hyperplasia at heel and toe was not significantly different from that seen in conventionally sutured anastomoses. CONCLUSIONS: During end-to-side bypass grafting, the temporary luminal arteriotomy seal provided a bloodless surgical field without interfering with recipient artery blood flow and with minimal damage to the arterial wall.

Anastomosis, Surgical↗
PubMed1998

Vertical displacement of the beating heart by the octopus tissue stabilizer: influence on coronary flow.

BACKGROUND: In beating heart coronary artery bypass graft operations, biventricular pump failure, as observed after exposure of the posterior circumflex branches by sternotomy, may originate from mechanical obstruction to coronary flow. METHODS: Regional coronary blood flow was measured in 8 anesthetized, paced, beta-blocked pigs, and the beating heart was fully retracted. RESULTS: Displacement decreased cardiac output from 4.8 +/- 1.1 L/min (mean +/- standard deviation) to 2.8 +/- 1.2 L/min (p < 0.001), a 42% +/- 6% decrease that resulted in a decrease in mean arterial pressure by 48% +/- 6% (mean +/- standard error of the mean; p < 0.001) and a reduction in coronary blood flow in the left anterior descending coronary artery, the right coronary artery, and the circumflex coronary artery by 34% +/- 6%, 25% +/- 8%, and 50% +/- 10%, respectively (all p < 0.05 versus baseline). Relative circumflex coronary artery flow was 20.1% +/- 8.3% lower than the combined relative value of left anterior descending coronary artery and right coronary artery flows (p = 0.046). Subsequent 20 degrees head-down tilt significantly increased ventricular preload pressures and restored cardiac output and mean arterial pressure as well as coronary blood flow. CONCLUSIONS: It is inferred that coronary blood flow was not mechanically obstructed during anterior displacement of the porcine beating heart, because augmentation of preloads by the maneuver of Trendelenburg restored coronary flow parallel to the recovery of cardiac output and mean arterial pressure while the heart remained retracted by 90 degrees.

Animals↗
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↗