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Biomedical subjects

G A Kaiser

Publications and source records attributed to G A Kaiser.

62 records · Page 4Linked to original sources
PubMedDate not supplied

Quantitation of platelet loss with indium-111 labeled platelets in a hollow-fiber membrane oxygenator and arterial filter during extracorporeal circulation in a pig model.

Platelet consumption in a hollow-fiber membrane oxygenator (HFMO) and arterial filter (AF) during cardiopulmonary bypass (CPB) was quantified in five pigs using Indium-111 labeled autologous platelets. Platelet labeling was performed 20-24 hours before CPB. After general endotracheal anesthesia, the pigs were systemically heparinized and were placed on CPB via a median sternotomy. After 3 hours of CPB, radioactivity was quantified with a gamma camera and an ionization chamber. The percent of injected dose (mean +/- SD) was 0.79 +/- 0.45 in the HFMO, 2.52 +/- 0.93 in AF, 4.3 +/- 1.2 in blood loss during CPB. Platelet consumption in HFMO during CPB was lower than in bubble oxygenators (19%) or silicone membrane oxygenators (12%) as observed in previous studies.

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PubMedDate not supplied

Platelet preservation during cardiopulmonary bypass with iloprost and Duraflo-II heparin-coated surfaces.

To test the hypothesis that temporary platelet inhibition during cardiopulmonary bypass (CPB) with surface heparinized systems may result in platelet preservation, nine Yorkshire pigs were placed on CPB for 3 hours. Platelet labeling was done in all pigs with Indium-111 tropolone. CPB was instituted with a roller pump, a hollow fiber membrane oxygenator (Bentley CM-50 [Baxter-Bentley Laboratories, Irvine, CA]), and an arterial filter. The extracorporeal perfusion systems were surface-coated with the Duraflo-II heparin complex. Group A pigs (n = 5) were systemically heparinized (activated coagulation time longer than 400 sec). Group B pigs (n = 4) were placed on CPB without systematic heparinization, but have received the stable prostacyclin-analog Iloprost (ZK36374) at 1 ng/kg/min i.v. from 30 min before and during CPB. Platelet counts declined in group A pigs at 5 min, 1 hr, 2 hr, and 3 hr of CPB to 79.8% (mean), 66.5%, 71.3%, and 69.0% of pre-CPB values, respectively (p less than 0.05). In group B pigs, mean platelet count during CPB was higher than 90% of control value. Percentage of injected radioactivity detected in the oxygenator was 2.82% in group A pigs versus 0.73% in group B pigs (p = 0.0541). Surface heparinization with the Duraflo II heparin coating complex in combination with Iloprost-induced temporary platelet inhibition resulted in platelet count preservation during CPB in the pig model.

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PubMedDate not supplied

Cardiopulmonary bypass with a surface-heparinized extracorporeal perfusion system.

To evaluate the effect of surface heparinization on platelet consumption during cardiopulmonary bypass (CPB) ten pigs were placed on CPB for 3 hours. All pigs were injected with autologous Indium-111 labeled platelets (300-420 uCi) 24 hours prior to CPB and were systemically heparinized prior to cannulation for CPB. CPB was established with a roller pump, a hollow fiber membrane oxygenator (HFMO, Bentley CM-50) and an arterial filter (AF, Bentley 1025). In six pigs the extracorporeal system was untreated whereas in four pigs it was surface heparinized with the Duraflo-II method. Cardiotomy suction was not used. Percent of injected radiation dose in HFMO and AF at 3 hours of CPB in the nontreated systems was 1.53 +/- 1.12 and 0.88 +/- 0.63%, whereas in the surface heparinized systems was 2.45 +/- 1.71 and 0.49 +/- 0.39% respectively (NS). (Values are mean +/- SD). Blood loss during (CPB) was 225 +/- 179 ml in the nontreated systems, and 263 +/- 103 ml in the surface heparinized systems (NS). Platelet counts were reduced by 12% or 21.8% at 3 hours of CPB in the two groups of pigs respectively (NS). No difference was observed in platelet consumption (in HFMO and in AF) or in platelet count reduction between the two groups of pigs. Surface heparinization did not improve platelet preservation in systemically heparinized pigs at 3 hours of CPB.

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PubMedDate not supplied

Increase of intraplatelet free calcium ion during extracorporeal circulation with a hollow fiber oxygenator: arterial filter and dynamics of platelet thrombosis on oxygenator and filter in a pig model.

Intraplatelet free calcium (IPFC) ions provide a common pathway for platelet activation leading to thrombosis and embolization. IPFC levels were determined by chlorotetracycline fluorometry during extracorporeal circulation (ECC) with systemic heparin in eight Yorkshire pigs (weighing 30-40 kg; 3 control and 5 ECC); the ratio of slow phase organelle calcium sequestration to fast phase platelet-membrane binding is an index of free calcium. During 3 hr of ECC with a hollow fiber oxygenator (HFO) (Bentley CM-50) and AF (Bentley 1025), seven blood samples were collected 5 min before and during ECC. The platelet deposition (CPM/microCi) on HFO (PDHFO) was simultaneously measured with In-111-labeled autologous platelets (300-400 microCi) and a Geiger probe detector at -5, 0, 5, 30, 45, 60, 120, and 180 min. During ECC, IPFC and HFO thrombus increase significantly (p less than 0.05) at 45 min with respect to control IPFC values of 0.4 +/- 0.1, suggesting direct participation of calcium activated platelets in thrombosis on HFO. The decline of IPFC is due to extrusion and sequestration by dense granules, and decline in HFO thrombus is due to embolization. On the other hand, the embolus in the arterial filter was trapped in a linear fashion, with a consistent increase with time of ECC.

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PubMedDate not supplied

Comparison of operations for coarctation of the aorta in infants.

During a 12-year-period, 33 infants 4 days to 1 year old underwent 36 operations for treatment of coarctation of the aorta. Associated cardiac anomalies were present in 27 infants (81.8%). All patients presented with congestive heart failure and underwent cardiac catheterization and aortography. Resection was performed in 11 infants, patch aortoplasty in 6, bypass in 2 and subclavian flap angioplasty in 17. Pulmonary artery banding was performed in 4 patients and ligation of a patent ductus arteriosus in 21 patients. Aortic crossclamp time was shorter in the 17 patients who had subclavian flap angioplasty than in 9 patients who had resection (P less than 0.05). Thirty-day mortality was 5 patients (13.9%); all were under 2 months of age at operation and had intracardiac anomalies. Four of them had resection and one had bypass. Mean follow-up was 5 years. Reoperation for recurrent or residual coarctation was performed in 5 patients after resection, 2 after patch aortoplasty and 2 after subclavian flap angioplasty. There was no significant difference in early postoperative arm-to-leg pressure gradients between patients who had resection and patients who had subclavian flap procedure. However, at last follow-up arm-to-leg pressure gradients were lower in 9 infants after subclavian flap (8 +/- 10.1 mmHg) than in 5 infants of similar age who had resection (34 +/- 23.9 mmHg) (P less than 0.05). Subclavian flap angioplasty is safe and more effective than resection for treatment of aortic coarctation in infants.

Aortic Coarctation↗