Cerebral blood flow changes during rat cardiopulmonary bypass and deep hypothermic circulatory arrest model: A preliminary study

The purpose of this study is to determine the effects of cardiopulmonary bypass (CPB) and deep hypothermic circulatory arrest (DHCA) on the viscoelasticity (viscosity and elasticity) of blood and global and regional cerebral blood flow (CBF) in a neonatal piglet model. After initiation of CPB, all animals ( n = 3) were subjected to core cooling for 20 min to reduce the piglets’ nasopharyngeal temperatures to 18°C. This was followed by 60 min of DHCA, then 45 min of rewarming. During cooling and rewarming, the alpha-stat technique was used. Arterial blood samples were taken for viscoelasticity measurements and differently labeled microspheres were injected at pre-CPB, pre- and post-DHCA, 30 and 60 min after CPB for global and regional cerebral blood flow calculations. Viscosity and elasticity were measured at 2 Hz, 22°C and at a strain of 0.2, 1, and 5 using a Vilastic-3 Viscoelasticity Analyzer. Elasticity of blood at a strain = 1 decreased to 32%, 83%, 57%, and 61% ( p = 0.01, ANOVA) while the viscosity diminished 8.4%, 38%, 22%, 26% compared to the baseline values ( p = 0.01, ANOVA) at pre-DHCA, post-DHCA, 30 and 60 min after CPB, respectively. The viscoelasticity of blood at a strain of 0.2 and 5 also had similar statistically significant drops ( p < 0.05). Global and regional cerebral blood flow were also decreased 30%, 66%, 64% and 63% at the same experimental stages ( p < 0.05, ANOVA). CPB procedure with 60 min of DHCA significantly alters the blood viscoelasticity, global and regional cerebral blood flow. These large changes in viscoelasticity may have a significant impact on organ blood flow, particularly in the brain.

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THE EFFECTS OF CARDIOPULMONARY BYPASS AND DEEP HYPOTHERMIC CIRCULATORY ARREST ON BLOOD VISCOELASTICITY AND CEREBRAL BLOOD FLOW

ASAIO Journal ◽

10.1097/00002480-199803000-00081 ◽

1998 ◽

Vol 44 (2) ◽

pp. 23A

Author(s):

&NA;

Keyword(s):

Blood Flow ◽

Cerebral Blood Flow ◽

Cardiopulmonary Bypass ◽

Circulatory Arrest ◽

Deep Hypothermic Circulatory Arrest ◽

Hypothermic Circulatory Arrest

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Effects of MK-801 and NBQX on Acute Recovery of Piglet Cerebral Metabolism after Hypothermic Circulatory Arrest

Journal of Cerebral Blood Flow & Metabolism ◽

10.1038/jcbfm.1994.21 ◽

1994 ◽

Vol 14 (1) ◽

pp. 156-165 ◽

Cited By ~ 19

Author(s):

Mitsuru Aoki ◽

Fumikazu Nomura ◽

Michael E. Stromski ◽

Miles K. Tsuji ◽

James C. Fackler ◽

...

Keyword(s):

Blood Flow ◽

Cerebral Blood Flow ◽

Oxygen Consumption ◽

Cardiopulmonary Bypass ◽

Circulatory Arrest ◽

High Energy ◽

Hypothermic Circulatory Arrest ◽

Cerebral Oxygen ◽

High Energy Phosphates ◽

Mk 801

Brain protection during open heart surgery in the neonate and infant remains inadequate. Effects of the excitatory neurotransmitter antagonists MK-801 and NBQX on recovery of brain cellular energy state and metabolic rates were evaluated in 34 4-week-old piglets (10 MK-801, 10 NBQX, 14 controls) undergoing cardiopulmonary bypass and hypothermic circulatory arrest at 15°C nasopharyngeal temperature for 1 h, as is used clinically for repair of congenital heart defects. MK-801 (dizocilpine) (0.75 mg/kg) or NBQX [2,3-dihydroxy-6-nitro-7-sulfamoyl-benzo( F)quinoxaline] (25 mg/kg) was given intravenously before cardiopulmonary bypass. Equivalent doses were placed in the cardiopulmonary bypass prime plus continuous infusions after reperfusion (0.15 mg kg−1h−1 and 5 mg kg−1h−1). Changes in high-energy phosphate concentrations and pH were analyzed by magnetic resonance spectroscopy in 17 animals until 225 min after reperfusion. Cerebral blood flow determined by radioactive microspheres as well as cerebral oxygen and glucose consumption were studied in 17 other animals. Cerebral blood flow and oxygen consumption were depressed relative to control by both MK-801 and NBQX at baseline. Recovery of phosphocreatine (p = 0.010), ATP (p = 0.030), and intracellular pH (p = 0.004) was accelerated by MK-801 and retarded by NBQX over the 45 min of rewarming reperfusion and the first hour of normothermic reperfusion. The final recovery of ATP at 3 h and 45 min reperfusion was significantly reduced by NBQX (46 ± 26% baseline, mean ± SD) versus control (81 ± 19%) and MK-801 (75 ± 8%) (p = 0.030). Cerebral oxygen consumption recovered to 105 ± 30% baseline in group MK-801 and 94 ± 31% in control but only to 61 ± 22% in group NBQX (p = 0.070). Cerebral blood flow stayed significantly lower in group NBQX relative to control. Thus, MK-801 accelerates recovery of cerebral high-energy phosphates and metabolic rate after cardiopulmonary bypass and hypothermic circulatory arrest in the immature animal. At the dosage used NBQX exerts an adverse effect.

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Global and regional cerebral blood flow in neonatal piglets undergoing pulsatile cardiopulmonary bypass with continuous perfusion at 25°C and circulatory arrest at 18°C

Perfusion ◽

10.1177/026765910101600610 ◽

2001 ◽

Vol 16 (6) ◽

pp. 503-510 ◽

Cited By ~ 7

Author(s):

Akif Ündar ◽

Takafumi Masai ◽

Shuang-Qiang Yang ◽

Harald C Eichstaedt ◽

Mary Claire McGarry ◽

...

Keyword(s):

Blood Flow ◽

Cerebral Blood Flow ◽

Cardiopulmonary Bypass ◽

Regional Cerebral Blood Flow ◽

Negative Impact ◽

Circulatory Arrest ◽

Deep Hypothermic Circulatory Arrest ◽

Regional Cerebral Blood ◽

Neonatal Piglets ◽

The Right

To investigate the influence of hypothermic cardiopulmonary bypass (HCPB) at 25°C and circulatory arrest at 18°C on the global and regional cerebral blood flow (CBF) during pulsatile perfusion, we performed the following studies in a neonatal piglet model. Using a pediatric physiologic pulsatile pump, we subjected six piglets to deep hypothermic circulatory arrest (DHCA) and six other piglets to HCPB. The DHCA group underwent hypothermia for 25 min, DHCA for 60min, cold reperfusion for 10 min, and rewarming for 40 min. The HCPB group underwent 15 min of cooling, followed by 60 min of HCPB, 10min of cold reperfusion, and 30 min of rewarming. The following variables remained constant in both groups: pump flow (150 ml/kg/min), pump rate (150 bpm), and stroke volume (1 ml/kg). During the 60-min aortic crossclamp period, the temperature was kept at 18°C for DHCA and at 25°C for HCPB. The global and regional CBF (ml/100g/min) was assessed with radiolabeled microspheres. The CBF was 48% lower during deep hypothermia at 18°C (before DHCA) than during hypothermia at 25°C (55.2± 14.3 ml/100 g/min vs 106.4±19.7 ml/100 g/min; p < 0.05). After rewarming, the global CBF was 45% lower in the DHCA group than in the HCPB group 48.3±18.1 ml/100 g/min vs (87±35.9 ml/100 g/min; p<0.05). Fifteen minutes after the termination of CPB, the global CBF was only 25% lower in the DHCA group than in the HCPB group (42.2±20.7 ml/100 g/min vs 56.4±25.8 ml/100 g/min; p=NS). In the right and left hemispheres, cerebellum, basal ganglia, and brain stem, blood flow resembled the global CBF. In conclusion, both HCPB and DHCA significantly decrease the regional and global CBF during CPB. Unlike HCPB, DHCA has a continued negative impact on the CBF after rewarming. However, 15 min after the end of CPB, there are no significant intergroup differences in the CBF.

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