The effects of air bubbles and time delay on blood gas analysis.
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Air↗
Biomedical subjects
C Borst
Publications and source records attributed to C Borst.
Cardiac acceleration elicited by voluntary muscle contractions of minimal duration.
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Adolescent↗
Relation between skeletal muscle contractions and heart rate acceleration.
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Ankle↗
Subintimal versus intraluminal laser-assisted recanalization of occluded femoropopliteal arteries: one-year clinical and angiographic follow-up.
PURPOSE: To compare the prolonged effect of subintimal versus intraluminal recanalization of occluded femoropopliteal arteries. PATIENTS AND METHODS: Recanalization of an occluded femoropopliteal artery was attempted in 63 patients (51 men, 12 women; mean age, 63 years) with lifestyle-limiting claudication and at least one patent distal artery. After assessment of baseline clinical and angiographic variables, mechanical passage was first attempted with use of a laser catheter with a 2.2-mm- diameter hemispherical contact probe that was connected to a neodymium: yttrium-aluminum-garnet laser. In case of failure, the laser was activated at 1-second pulses of 15 W. In some cases additional guide-wire and catheter manipulations were used. Successful recanalization was followed by standard balloon dilation. An intense antithrombotic regimen was used. RESULTS: The occluded artery could be entered in 62 of 63 patients. The catheter was assumed to have followed a subintimal course in 20 patients (group A) and an intraluminal course in 42 patients (group B). Successful recanalization was achieved in 17 patients (85%) of group A and in 36 (86%) of group B. No significant differences were found in clinical and angiographic follow-up measurements between the two groups. The angiographic cumulative primary patency rate (open vs closed) at 1 year was 93% +/- 6 in group A and 93% +/- 4 in group B. The cumulative restenosis/reocclusion-free patency rate was 63% +/- 13 and 65% +/- 9 for groups A and B, respectively. Median length of the original occlusion (8.0 cm in group A vs 4.5 cm in group B) was the only distinguishing baseline variable between the groups (P < .02) and was also the single independent predictor of recurrent flow limitation (P = .0017). Significant complications were distal embolization in three patients, followed by death in one patient and puncture site bleeding in two patients. CONCLUSION: The 1-year clinical and angiographic results of assumed subintimal and intraluminal recanalization are comparable. Thus, a subintimal course per se should not be regarded as a failure of the procedure.
Angioplasty, Balloon, Laser-Assisted↗
Continuous 24-hour intra-arterial blood pressure recording in the conscious unrestrained rabbit.
A measuring system is described for the long-term continuous beat-to-beat measurement of mean aortic pressure and heart period (interval between beats) in the conscious unrestrained rabbit. Pressures and heart periods were collected in hourly histograms. The histograms were summed into day (0800-2000 h), night (2000-0800 h) and 24-hour histograms. Separate histograms were formed for resting and active periods. From each histogram the mean value, standard deviation, fifth percentile, 50th percentile and 95th percentile were calculated and stored on a floppy disc together with the histograms. Off-line, histograms and their descriptive parameters were plotted and sent to a HP1000 computer for bulk storage and further analysis. The measuring system is capable of handling up to eight animals simultaneously for an indefinite period. The design functioned properly in the long-term measurement (more than 4 weeks) of mean level and variability of arterial pressure and heart period. The measuring system is useful in the study of arterial blood pressure behaviour after sino-aortic denervation and in the evaluation of drug effects in conscious animals.
Animals↗
Thrombogenicity and intimal hyperplasia after conventional and thermal balloon dilation in normal rabbit iliac arteries.
Acute occlusion and restenosis are the major complications of percutaneous transluminal coronary balloon angioplasty. Application of heat during balloon dilation was postulated to reduce these complications. We evaluated thrombogenicity and intimal hyperplasia of normal rabbit iliac arteries after conventional (37 degrees C) and thermal balloon dilation. Thermal dilation was performed with a radio-frequency-heated balloon, provided with three thermocouples attached to the inside of the balloon skin. In a previous in vitro study, thrombogenicity of human subendothelium was increased at 55 degrees C and greatly decreased at temperatures over 70 degrees C. Thermal balloon dilation was therefore performed at 55 and 90 degrees C in vivo. Rabbits survived 2 h for evaluation of platelet adhesion or either 3 or 8 weeks for intimal hyperplasia. Angiograms revealed no occlusions or thrombi after any procedure. Platelet adhesion was quantified on 20 scanning electron microscopic pictures per balloon dilation site and was expressed as the percentage of the luminal surface covered by platelets. Platelet adhesion was similar in all groups, although large thrombi were present in the 90 degrees C group. Intimal hyperplasia was measured morphometrically at regular intervals over the balloon site. After 3 weeks, the average intimal hyperplasia was significantly reduced in the 90 degrees C balloon dilation group, which was mainly due to the absence of intimal hyperplasia in the midpart of these segments. After 8 weeks, intimal hyperplasia was equal in all groups. Thus, in the applied model, platelet coverage was equal after conventional balloon angioplasty and after 55 and 90 degrees C balloon angioplasty.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
In the normal rabbit femoral artery increasing arterial wall injury does not lead to increased intimal hyperplasia.
Angioplasty inflicts damage to the arterial wall. We studied whether augmented medial smooth muscle cell necrosis leads to augmented intimal hyperplasia and thus aggravates restenosis. Sixty-three normal femoral arteries of New Zealand White rabbits were overstretched with an angioplasty balloon during either maximal vasoconstriction with phenylephrine (32 arteries) or maximal vasodilation with nitroprusside (31 arteries). After 3 days' survival, medial necrosis was determined as percentage of cross-sectional medial area. In the 3 weeks' survival group, intimal hyperplasia was quantified as its average thickness. The dilation ratios, i.e. balloon diameter divided by arterial diameter at the time of dilation, were significantly higher in the 3 days' and 3 weeks' vasoconstriction groups (VC groups), respectively: 1.96 +/- 0.10 (mean +/- SD) and 2.14 +/- 0.08 in the VC groups versus 1.27 +/- 0.03 and 1.32 +/- 0.05, respectively, in the vasodilation groups (VD groups) (both p < 0.001). Medial necrosis was more extensive in the VC group (64 +/- 5%) than in the VD group (23 +/- 7%, p < 0.001) and proportional to the dilation ratio (r = 0.69, p < 0.01). Intimal hyperplasia, however, was equal in the VC (59 +/- 8 microns) and VD (57 +/- 6 microns, NS) groups and not dependent on dilation ratio (r = 0.10). Thus, extensive medial necrosis produced during balloon dilation in maximally vasoconstricted arteries did not lead to more intimal hyperplasia than when less medial necrosis was induced by balloon dilation during vasodilation.
Angioplasty, Balloon↗
Endothelial cell recoverage and intimal hyperplasia after endothelium removal with or without smooth muscle cell necrosis in the rabbit carotid artery.
Interventional-injury-induced intimal hyperplasia involves smooth muscle cell proliferation that may be limited by endothelial cell coverage. We hypothesized that endothelial cell coverage modulates intimal hyperplasia. Therefore rabbit carotid arteries were injured with (2-french Fogarty balloon) and without media necrosis (Prolene loop). After termination at 3, 7, 21, or 42 days, endothelial cell coverage was assessed with an antibody to CD31 and cross-sectional intimal hyperplasia area was measured morphometrically. At 21 and 42 days, maximal intimal hyperplasia thickness was measured at a site where endothelium was present and where endothelium was absent. Proliferating cells were identified with an antibody to the nuclear antigen Ki-67. From 3 to 42 days, endothelial cell coverage progressed from the caudal and cranial ends of the lesion towards the center and was slower in balloon- versus loop-injured arteries (p<0.001, Anova). At 21 and 42 days, intimal hyperplasia area was larger after balloon than after loop injury (21 days: 0.20 +/- 0.01 vs. 0.09 +/- 0.04 mm2, p<0.05; 42 days: 0.26 +/- 0.03 vs. 0.08 +/- 0.02 mm2, p<0.01). At 21 days, the intimal hyperplasia was maximal at the center of the lesion and diminished towards the edges in both balloon- and loop-injured arteries. Surprisingly, at 21 and 42 days, maximal intimal hyperplasia thickness was larger in CD31-positive compared to CD31-negative regions (104 +/- 8 vs. 72 +/- 12 micron, p<0.01, paired t test). At 3 and 7 days, more medial proliferation was found after balloon than after loop injury (3 days: 46.2 +/- 8.8 vs. 0.2 +/- 0.1%, p<0.01; 7 days: 18.5 +/- 6.4 vs. 1.0 +/- 0.4%, p<0.01). In the same period, abundant adventitial proliferation was found after balloon injury that was entirely absent after loop injury. We conclude, first, that endothelial cell recoverage proceeded at a lower rate over damaged than over normal media. This retarded endothelial cell recoverage may contribute to enhanced intimal hyperplasia. Second, at a late stage of vascular healing, when intimal hyperplasia had already been formed, reendothelialization seems to have been enhanced over areas with thick intimal hyperplasia. Third, dilation-induced medial damage was accompanied with massive adventitial cell proliferation.
Animals↗
Thrombogenicity of the human arterial wall after interventional thermal injury.
Thermal injury has been shown to reduce platelet adhesion (PA) in vitro but not in vivo. The controversy may be based on the mode of thermal injury, the anticoagulation regimen, or species differences. Human and rabbit arteries were dilated by a radio-frequency (RF)-heated balloon (RF dilation) or by immersion in heated buffer. The artery segments were perfused in an annular perfusion chamber with blood anticoagulant by citrate or heparin (37 degrees C, 5 min, shear rate: 1,300 s-1). To determine PA to deep wall layers, 6-micron cross-sections of heated arteries were perfused in a rectangular perfusion chamber (37 degrees C, 5 min, 1,300 s-1). After RF dilation of human arteries at 55 and 90 degrees C, subendothelical PA (citrated blood) decreased from 28.9% at 37 degrees C to 6.8%, and increased to 39.6%, respectively (in both cases p<0.05). Heparin anticoagulation resulted in subendothelial fibrin deposition that was equal after 37 and 90 degrees C, and decreased after 55 degrees C. Heating of cross-sections of atherosclerotic coronary arteries to 55 and 90 degrees C, showed increased and decreased PA, respectively, to the intima and media. No effect was observed on the highly reactive adventitia and atherosclerotic plaque. We conclude that thermal balloon angioplasty at 90 degrees C reduces PA to the arterial subendothelium, but not to the adventitia or the atherosclerotic plaque. As thermal balloon angioplasty in patients will always produce a region with increased PA at 55 degrees C and as heparin anticoagulation permits fibrin deposition that is not affected by heat, it is unlikely that thermal balloon angioplasty alone will reduce thrombotic complications.
Angioplasty, Balloon↗
The influence of lesion length on intimal hyperplasia after Fogarty balloon injury in the rabbit carotid artery: role of endothelium.
After balloon angioplasty, retarded endothelial cell recoverage of the injured segment may lead to enhanced intimal hyperplasia. We tested the hypothesis that long lesions result in more intimal hyperplasia than short lesions due to a prolonged time to complete endothelial cell recoverage. A 2-french Fogarty balloon was used to create 2.5- and 5-cm-long lesions in the rabbit carotid artery. After termination, the injured arteries (n = 9 for all groups) were serially processed for histochemistry. Endothelial cell coverage was assessed with an antibody to CD31 and cell proliferation with a monoclonal antibody to Ki-67 nuclear antigen. The intimal hyperplasia cross-sectional area was measured morphometrically. All data are mean +/- SEM. At 21 days, endothelial cell recoverage was almost complete in the 2.5-cm lesions. In the 5-cm lesions, endothelial cell recoverage was 66 +/- 6% in the middle segments (p = 0.04, 2.5 vs. 5 cm) and 100% at the cranial and caudal ends of the lesion. At 42 days, endothelial cell coverage had increased to 81 +/- 7% in the middle segments of the 5-cm lesions. The intimal hyperplasia area was similar in the 2.5- and the 5-cm lesions both at 21 days (0.19 +/- 0.02 and 0.20 +/- 0.01 mm2, respectively) and 42 days (0.27 +/- 0.02 and 0.26 +/- 0.03 mm2, respectively). The increase in intimal hyperplasia from 21 to 42 days was significant for both lesion lengths (p = 0.004). At 21 days, intimal proliferation was similar for the 2.5- and 5-cm lesions. After 42 days postinjury, intimal proliferation had decreased (p < 0.001) equally for both lesion lengths. Earlier recoverage by endothelium in the 2.5-cm lesions did not inhibit intimal hyperplasia compared to the 5-cm lesions which were still incompletely reendothelialized. We conclude that in the rabbit, rapid endothelial cell recoverage of Fogarty balloon-injured arteries may not limit intimal hyperplasia in the center of the lesion. It is conceivable that the inability of regenerated endothelium to inhibit intimal hyperplasia is due to its initially dedifferentiated and possibly dysfunctional phenotype.
Angioplasty, Balloon↗