Onset Of Cardiopulmonary Bypass Research Articles

Abstract 1357: Mobility of Epicardial Rotors During Human Ventricular Fibrillation

Introduction: Stability of reentry during VF may depend on the dynamics of rotor cores. We determined the mobility of rotors during human VF using global epicardial mapping and phase singularity analysis. Methods: In 10 patients undergoing cardiac surgery (6 with coronary artery disease; 4 with aortic valve disease), VF was induced by burst pacing prior to (n=7) or immediately following (n=3) the onset of cardiopulmonary bypass. For each subject, a 20 – 40 s episode of fibrillatory activity was sampled at 1 kHz using an epicardial sock containing 256 unipolar contact electrodes connected to a UnEmap system. Trajectories of persistent epicardial rotors (singularities of phase maps, based on de-trended voltage versus its Hilbert transform, lasting for > 1000 ms) were tracked. The mean core location was determined across the lifetime of each persistent rotor. The rotor was classified as stationary if its core remained within 15 mm of the mean location for more than 90% of its duration. Results: Using the above criteria, the numbers of mobile and stationary rotors varied from patient-to-patient (see figure ). In all but one patient, there were more mobile than stationary rotors. Over all patients, the mean ± SD number of mobile rotors (32 ± 21) was significantly greater than stationary rotors (7 ± 6, P<0.01). Conclusions: At least one stationary rotor was always present during human VF, but it is predominantly characterised by a small number of persistent mobile rotors.

Simvastatin reduces platelet–endocardium adhesion in atrial fibrillation

ObjectivesTo evaluate the relationship between CD40/CD40L system and increased thrombogenesis in AF, and to test the effects of simvastatin treatment. MethodsIn vitro study using human tissue, University Hospital (tertiary referral center). Experiments on right atrial segments obtained before the onset of cardiopulmonary bypass were done in either presence or absence of 5μM simvastatin. Two groups of patients in either chronic atrial fibrillation or sinus rhythm at the time of cardiac surgery. The endocardial expression of CD40, the release of CD40L, and adhesion of platelets to endocardium. Additionally, the thickness of platelet aggregates and the platelet distribution on the endocardium were also evaluated. ResultsAtrial fibrillation was associated with a significant increase of endocardial CD40 expression (293.1±55.1pg/ml vs. 230.9±53.3pg/ml, p<0.01), and platelet–endocardial adhesion compared with sinus rhythm atria (10.8±2.2 vs. 5.2±1.3 platelet CD41 AU p<0.01). At immunofluorescence about 62% of fibrillating endocardium was covered by platelets, compared with 12% of not sinus rhythm atria. Addition of simvastatin significantly reduced CD40 expression as well as platelet adhesion to fibrillating atria; its efficacy was not reversed by the addition of mevalonic acid. ConclusionsChronic atrial fibrillation acutely upregulates CD40 expression as well as platelet adhesion to the endocardium. Simvastatin is effective in modulating this expression, thus it may potentially contribute to reduce the risk of intra-atrial thrombus formation.

Glycopeptide pharmacokinetics in current paediatric cardiac surgery practice☆

To examine the evolution of serum concentrations of prophylactic glycopeptides administered during state-of-the-art cardiopulmonary bypass (CPB) and vigorous haemodiafiltration in paediatric patients undergoing cardiac surgery. We enrolled infants and children <3 years of age who, based on the preoperative microbiological screening, age and surgical complexity, were at high risk of methicillin-resistant Staphylococcus aureus (MRSA) infection. Antimicrobial prophylaxis with glycopeptides was administered to 22 patients, randomly assigned to vancomycin (VAN; n=11) versus teicoplanin (TEC; n=11). Fixed doses of each drug (15 mg/kg for VAN and 8 mg/kg for TEC) were administered immediately before the operation, at the time of priming of the extracorporeal circuit, upon admission to the intensive care unit and for 48 h thereafter, q. 8 h for VAN, and once daily for TEC. Vigorous haemodiafiltration was applied during and briefly after CPB. The second dose of drug added to the prime prevented a fall in serum drug concentrations at the onset of CPB in both groups. A 77% decrease in VAN, versus 53% in TEC concentrations, was observed after the conclusion of CPB. Serum concentrations of TEC>10 microg/ml were observed throughout the treatment period in 91% of patients, while 55% of patients assigned to VAN had serum concentrations consistently >5 microg/ml (p=0.08). Therapeutic serum concentrations were maintained throughout the intraoperative period, particularly with TEC, administered before the first surgical incision, followed by a supplemental bolus in the priming fluid of CPB. Postoperative surgical wound infections occurred in neither group. The prophylactic use of glycopeptides in paediatric patients at high risk of MRSA infection undergoing cardiac surgery was safe and effective. TEC might be the drug of choice, since stable, therapeutic serum concentrations were easily maintained throughout the treatment period.

Desflurane preconditioning in coronary artery bypass graft surgery: a double-blinded, randomised and placebo-controlled study

Recent clinical and experimental data indicate that volatile anaesthetics may precondition myocardium against ischaemia and infarction. The present clinical trial was designed to verify the cardioprotective effects of desflurane in patients undergoing elective coronary artery bypass surgery. It was hypothesized that desflurane preconditioning would decrease postoperative release of troponin I and brain natriuretic peptide (NT-proBNP). Besides, we have hypothesized that desflurane preconditioning would preserve the myocardium from the dysfunction following cardioplegic arrest. Twenty-eight patients were randomly divided into two groups: Control group (14 patients) and Desflurane group (14 patients). In Desflurane group (DS) patients, preconditioning was elicited after the onset of cardiopulmonary bypass via a 5-min exposure to desflurane (2.5 minimum alveolar concentration), followed by a 10-min washout before aortic cross-clamping and cardioplegic arrest. The control group (C) patients underwent an equivalent period (15 min) of pre-arrest desflurane-free bypass. Haemodynamic measurements were obtained at six different times. The biochemistry markers of cellular damage and myocardial dysfunction (troponin I, NT-proBNP) were determined. Left ventricular (LV) function was assessed using tissue Doppler imaging (TDI) of mitral annulus. Two-factor repeated-measures analysis of variance was used to evaluate differences over time between groups for all parameters determined in plasma samples and for all TDI-derived variables. After surgery, both the troponin I values (2.04+/-1.09 ng/ml vs 1.44+/-0.77 ng/ml, p<0.01 after 24h and 1.62+/-0.96 ng/ml vs 1.00+/-0.24 ng/ml, p<0.01 after 72 h respectively) and those of the NT-proBNP (2187+/-282.9 ng/l vs 885.4+/-117.35 ng/l, p<0.01 after 24h and 3097.9+/-226.2 vs 1393.6+/-312.07 ng/l, p<0.01 after 72 h respectively) were less in the desflurane-treated patients. The values of TDI of mitral annulus were constantly better in desflurane-treated patients. We can conclude that the use of desflurane in these patients provides a pharmacological preconditioning so as to reduce myocardial necrosis and improve the cardiac performance in the postoperative period.

Effect of cardiopulmonary bypass on CD11/CD18 expression of neutrophils in children undergoing cardiac surgery

To investigate the changes in perioperative expression level of CD11/CD18 of neutrophils in children undergoing cardiac surgery with cardiopulmonary bypass (CPB). Thirty children patients with congenital heart disease underwent cardiac surgery with CPB (CPB group) and the control group consisted of 20 children who received thoracic or general surgery without CPB. Blood samples were drawn at the following time points: pre-surgery, 15 min after onset of CPB, immediately after CPB, 2 h after surgery and on the 1st, 2nd, 3rd postoperative day. D11/CD18 expression on neutrophils and serum concentration of IL-6 and IL-8 were analyzed by flow cytometry and enzyme-linked immunosorbent assay, respectively. In CPB group plasma levels of IL-6 and IL-8 increased significantly and peaked at 2 h after initiation of CPB (P<0.05), and descended to the after-anesthesia level at 3rd day after operation. In non-CPB group there was a similar trend of changes in IL-6 and IL-8, but to a much lesser extent. The level of CD11b/CD18 in CPB group began to increase significantly and peaked at 15 min after initiation of CPB (P <0.05), and descended to the after-anesthesia level at 2 h after operation. There was no significant changes of CD11b/CD18 in control group (P >0.05). No significant differences were detected at any time points with respect to expression of CD11a/CD18 and CD11c/CD18 in both groups (P >0.05). CPB surgery of children can cause increasing of the CD11b/CD18 expression level of neutrophil but has no significant effect on CD11a/CD18 and CD11c/CD18. CD11b/CD18 may play an important role in the systemic inflammation induced by CPB.

Large-Dose Propofol During Cardiopulmonary Bypass Decreases Biochemical Markers of Myocardial Injury in Coronary Surgery Patients: A Comparison with Isoflurane

We investigated if increasing propofol's dosage to augment its antioxidant capacity during cardiopulmonary bypass (CPB) could confer cardiac protection. Fifty-four coronary artery bypass graft surgery patients were randomly assigned to small-dose propofol (Group P; n = 18), large-dose propofol (Group HiP; n = 18), or isoflurane Group (Group I; n = 18). After the induction, anesthesia was maintained with an inspired concentration of isoflurane 1%-3.5% (Group I) or a continuous infusion of propofol 60 microg x kg(-1) x min(-1) (Group P) throughout the surgery. In Group HiP, this dose of propofol was increased to 120 microg x kg(-1) x min(-1) for 10 min before the onset of CPB until 15 min after aortic unclamping and then decreased to 60 microg x kg(-1) x min(-1) until the end of surgery. The duration of aortic cross-clamping was 83 +/- 24, 88 +/- 22, and 81 +/- 20 min in Group P, Group HiP, and Group I, respectively (P > 0.1). Plasma malondialdehyde, a marker of oxidative stress, was significantly lower at 8 h after CPB, and Troponin I was lower at 24 h after CPB in Group HiP compared with Group P and Group I (P < 0.05). There was a significant reduction in inotropic requirements for separation from CPB in Group HiP compared with Group I. Postoperative systemic vascular resistance was significantly reduced in Group HiP as compared with Group I. Mean cardiac index was significantly higher at 24 h after CPB in Group HiP compared with Group P and Group I (P < 0.05) (Group I, 2.2 +/- 0.1; Group P, 2.3 +/- 0.2; and Group HiP, 2.8 +/- 0.3 L x min(-1) x m(-2), respectively). The duration of intensive care unit stay was significantly shorter in Group Hi-P compared with Group I. We conclude that administration of a large dose of propofol during CPB attenuates postoperative myocardial cellular damage as compared with isoflurane or small-dose propofol anesthesia.

Troponin T elevation after coronary bypass surgery: clinical relevance and correlation with perioperative variables

Elevation in markers of myocardial necrosis is a common feature following coronary artery bypass surgery, but its relevance is unclear. The objective of this study was to evaluate the association between postoperative troponin T elevation, perioperative variables and clinical outcomes. We evaluated 100 low-risk patients undergoing first-time elective on-pump coronary artery bypass surgery. The mean age was 62 +/- 9.8 years and 83% were male; patients with diabetes mellitus, renal failure and impaired left ventricular function (ejection fraction < 40%) were excluded. Troponin levels were measured at baseline and 12 and 24 h following the onset of cardiopulmonary bypass. Predefined clinical endpoints included death, new Q waves on 12-lead electrocardiogram and inotropic requirement. Postoperative troponin elevation occurred in 95%. Troponin T elevation was related to the duration of cardiopulmonary bypass (P = 0.0001) and aortic cross-clamp time (P = 0.0003). There was also an inverse relationship with perioperative core temperature (P = 0.0001). There was no association between postoperative troponin elevation and clinical outcomes. Postoperative troponin T elevation occurs in the majority of patients undergoing elective on-pump coronary artery bypass surgery. In this low-risk cohort, troponin T elevation was associated with procedural duration but not with clinical outcome.

Do Surface-Modifying Additive Circuits Reduce the Rate of Cerebral Microemboli During Cardiopulmonary Bypass?

The objective of this study was to determine if surface-modifying additive (SMA) cardiopulmonary bypass (CPB) circuits are associated with a lower rate of cerebral microemboli during CPB compared with standard circuits. In a 2 × 2 factorial design, patients undergoing coronary artery bypass graft surgery were randomized to SMA or standard CPB circuits (with and without methyl-prednisolone). Transcranial Doppler was used to detect high-intensity transient signals (HITS) in both middle cerebral arteries. HITS were counted from onset to end of CPB. Intervals of interest were as follows: period 1, from CPB onset to aortic cross-clamping; period 2, from aortic cross-clamping to immediately before de-clamping; period 3, from aortic de-clamping to before aortic side-clamping; period 4, from the application of the aortic side clamp to immediately before the release of the side clamp; period 5, from aortic side clamp release to the end of CPB. There were 14 patients in each circuit group. No significant differences were found on the partial and total counts of HITS (medians [25th, 75th percentile]) between patients exposed to standard (total count: 228 HITS [174, 280]) and SMA circuits (total count: 156 HITS [104, 356]; p = .427). The median of the sum of HITS per patient associated with perfusionist interventions was not different between both circuit groups (standard: 17 HITS [7, 80]; SMA: 43 HITS [13, 168]; p = .085). This study, with a sample size of 28 patients, indicates that it is unlikely to find any difference in the count of HITS during CPB that is greater than 117 HITS between the two CPB circuits. Moreover, our findings emphasize the relevance of minimizing additional sources of cerebral microembolization during CPB that are not directly related to the biocompatible nature of the SMA CPB circuit.

Changes in Cerebral Vascular Reactivity Occur Early During Cardiopulmonary Bypass in the Rat

Cardiopulmonary bypass (CPB) is known to cause cerebrovascular dysfunction. The etiology of these complications is complex, but disruption of normal cerebral endothelial function as a consequence of inflammatory or hypoperfusion phenomena have been implicated. The aim of this study was to investigate the effect of CPB time on cerebrovascular reactivity and to investigate the correlation of these findings with measured inflammatory markers. Cardiopulmonary bypass was carried out for 30 or 60 minutes on two groups of rats. Sham groups underwent the same surgical procedure without CPB. The middle cerebral artery was harvested and prepared for assessment of induced endothelial and vascular smooth muscle cell responses. Systemic inflammation was evaluated by measuring tumor necrosis factor-alpha and immunohistochemical staining for intercellular adhesion molecule-1. Acetylcholine caused a dose-dependent vasodilation in the control groups that was absent in animals undergoing CPB (21.3% +/- 1.3% increase in diameter at 30 minutes in the sham group compared with 5.4% +/- 1.1% in the corresponding CPB group, p < 0.001). Significantly, this was apparent after only 30 minutes of CPB. Cardiopulmonary bypass did not alter the response to sodium nitroprusside (45.3% +/- 8.6% after 30 minutes in the sham group compared with 57.8% +/- 8.0% in the corresponding CPB group, p < 0.2). Furthermore, the contractile response to serotonin remained intact in all groups (32.9 +/- 4.6 and 27.6 +/- 2.6 at 30 and 60 minutes, respectively, in the sham groups compared with 23.1 +/- 1.6 and 28.0 +/- 4.4 in the corresponding CPB groups, p < 0.2). Cardiopulmonary bypass also led to an early and marked increase in tumor necrosis factor-alpha and overexpression of intercellular adhesion molecule-1. Cerebrovascular impairment appears early after the onset of CPB. The specific loss of acetylcholine-induced vasodilation suggests endothelial cell dysfunction rather than impaired vascular smooth muscle response to nitric oxide. This loss of endothelium-dependent regulatory factors after CPB may enhance vasoconstriction, impair cerebrovascular function, and contribute to neurologic injury after CPB.

Methylthioninium chloride administration at the onset of cardiopulmonary bypass (CPB) in patients receiving ACE inhibitors

Methylthioninium chloride administration at the onset of cardiopulmonary bypass (CPB) in patients receiving ACE inhibitors

The Hemodynamic Effects of Methylene Blue When Administered at the Onset of Cardiopulmonary Bypass

Hypotension occurs during cardiopulmonary bypass (CPB), in part because of induction of the inflammatory response, for which nitric oxide and guanylate cyclase play a central role. In this study we examined the hemodynamic effects of methylene blue (MB), an inhibitor of guanylate cyclase, administered during cardiopulmonary bypass (CPB) to patients taking angiotensin-converting enzyme inhibitors. Thirty patients undergoing cardiac surgery were randomized to receive either MB (3 mg/kg) or saline (S) after institution of CPB and cardioplegic arrest. CPB was managed similarly for all study patients. Hemodynamic data were assessed before, during, and after CPB. The use of vasopressors was recorded. All study patients experienced a similar reduction in mean arterial blood pressure (MAP) and systemic vascular resistance (SVR) with the onset of CPB and cardioplegic arrest. MB increased MAP and SVR and this effect lasted for 40 minutes. The saline group demonstrated a persistently reduced MAP and SVR throughout CPB. The saline group received phenylephrine more frequently during CPB, and more norepinephrine after CPB to maintain a desirable MAP. The MB group recorded significantly lower serum lactate levels despite equal or greater MAP and SVR. In conclusion, administration of MB after institution of CPB for patients taking angiotensin-converting enzyme inhibitors increased MAP and SVR and reduced the need for vasopressors. Furthermore, serum lactate levels were lower in MB patients, suggesting more favorable tissue perfusion.

Myocardial Ischemia Revisited

Does perioperative myocardial ischemia lead to postoperative myocardial infarction? By Stephen Slogoff and Arthur S. Keats. Anesthesiology 1985; 62:107-14. Reprinted with permission. To determine if a relationship exists between perioperative myocardial ischemia (ST segment depression greater than or equal to 0.1 mV) and postoperative myocardial infarction (PMI), nonparticipating observers recorded all electrocardiographic, hemodynamic, and other events between arrival of patients in the operating room and onset of cardiopulmonary bypass during 1,023 elective coronary artery bypass operations (CABG). The roles of preoperative patient characteristics, quality of the operation limited by disease as rated by the surgeon and duration of ischemic cardiac arrest as risk factors for PMI also were quantified. Electrocardiographic ischemia occurred in 36.9% of all patients, with almost half the episodes occurring before induction of anesthesia. PMI was almost three times as frequent in patients with ischemia (6.9% vs. 2.5%) and was independent of when ischemia occurred. Ischemia was related significantly to tachycardia but not hypertension nor hypotension and was frequent in the absence of any hemodynamic abnormalities. The anesthesiologist whose patients had the highest rate of tachycardia and ischemia had the highest rate of PMI. Although neither single nor multiple preoperative patient characteristics related to PMI, suboptimal quality of operation and prolonged ischemic cardiac arrest increased the likelihood of PMI independent of the occurrence of myocardial ischemia. The authors conclude that perioperative myocardial ischemia is common in patients undergoing CABG, occurs randomly as well as in response to hemodynamic abnormalities, and is one of three independent risk factors the authors identified as related to PMI. PMI is unrelated to preoperative patient characteristics such as ejection fraction and left main coronary artery disease, and its frequency will relate primarily to perioperative management rather than patient selection.

Residual air in the venous cannula increases cerebral embolization at the onset of cardiopulmonary bypass

When the right atrium (RA) cannula is connected to the venous return line of the cardiopulmonary bypass (CPB) circuit, air is often introduced. Air in the venous cannula may increase cerebral air embolization at initiation of CPB despite the arterial line filter. We measured the volume of air present in the venous cannula after cannulation of the RA. Transcranial Doppler quantified emboli as high-intensity transient-signals (HITS) in both middle-cerebral arteries (MCA) at the beginning of CPB. After RA cannulation, the air column in the venous line was measured and the total volume calculated using the known lumen diameter. CPB onset was defined as the instant when the CPB machine started moving the patient's blood from the RA into the venous reservoir. Starting from CPB onset, HITS were counted: (a) until completion of the first minute on CPB (1-min count) and (b) until aortic cross clamping (pre-clamping count). We studied 135 patients during coronary artery bypass surgery operated on by 10 cardiac surgeons. HITS during onset of CPB were detected in 95% of patients. Median counts were 10 HITS (25th, 75th percentiles: 3, 26) at 1-min and 21 HITS (8, 51) during pre-clamping. A significant correlation was found between the volume of air in the venous cannula and the HITS counts (r=0.524, p<0.0001). Absence of retained air was associated with lower HITS counts [3 HITS (1, 11)] compared with any amount of air [13 HITS (4, 29), p=0.002)]. The volume of air in the venous cannula, the MCA mean blood flow velocity and the pre-clamping time were the only independent predictors of the pre-clamping HITS counts (p<0.001). Air in the venous cannula can result in HITS in the MCA. Minimizing the volume of air introduced into the venous cannula after cannulation of the RA can decrease cerebral air embolization at the beginning of CPB.

A randomized, double-blind, placebo-controlled trial of a COX-2 inhibitor (Rofecoxib) in patients undergoing coronary artery bypass surgery

The endothelium of patients with coronary artery disease shows increased expression of cyclooxygenase-2 (COX-2) during coronary artery bypass graft surgery (CABG) using cardiopulmonary bypass. This, together with serotonin, may lead to coronary microvessel spasm, which potentially, can contribute to myocardial ischemia and injury after surgery. We performed a randomized, double-blind, placebo-controlled trial in patients undergoing isolated CABG to determine whether short-term treatment with a selective COX-2 inhibitor, Rofecoxib (25 mg), given preoperatively and for 5 days after operation, can offer better myocardial protection in patients undergoing CABG by measuring serial cardiac troponin T (cTnT) levels. The study was powered to recruit 150 consecutive patients undergoing isolated CABG but the study was terminated prematurely by the worldwide withdrawal of rofecoxib. There were highly statistically significant (P<0.001) increases in cTnT in both groups at each time point (1, 6, 24 and 48 h after onset of cardiopulmonary bypass) compared to preoperative levels. cTnT levels were similar at all post-operative time points between the 2 groups. There is no evidence that short-term treatment with rofecoxib has a myocardial protective effect in patients undergoing CABG. There is also no evidence that its effect is deleterious to the myocardium in patients undergoing CABG.

Brain natriuretic peptide elevation and the development of atrial fibrillation following coronary artery bypass surgery

The study was designed to determine whether the development of atrial fibrillation is associated with post-operative left ventricular dysfunction and subsequent left atrial stretch. We recruited 133 patients with well preserved pre-operative left ventricular function undergoing bypass surgery. Brain natriuretic peptide was measured at baseline, 24 and 48 h after the onset of cardiopulmonary bypass, and patients were monitored for 72 h after surgery. Atrial fibrillation occurred in 65 patients. Median 48 h brain natriuretic peptide levels were greater in the atrial fibrillation group (440 pg/ml (AF) and 319 pg/ml (non AF) P=0.001). As atrial fibrillation can cause an elevation in brain natriuretic peptide we divided the subjects into early atrial fibrillation (<48 h) and late (>48 h). In those with early atrial fibrillation there was no difference in the 24 h brain natriuretic peptide levels (381 pg/ml and 365 pg/ml P=0.73). In those with late atrial fibrillation the median 48 h brain natriuretic peptide level was greater than in the control group (405 pg/ml and 319 pg/ml, respectively, P=0.02). Brain natriuretic peptide levels rise significantly following bypass surgery. This increase was more evident in those who develop late atrial fibrillation which may suggest a role for atrial stretch in this arrhythmia.

Blood phagocyte activation during open heart surgery with cardiopulmonary bypass

Open heart surgery with a cardiopulmonary bypass (CPB) is associated with a systemic inflammatory response which significantly contributes to adverse postoperative complications. The purpose of this study was to characterize the activation of blood phagocytes during open heart surgery with CPB. Blood samples were collected during and up to 24 h after surgery. The production of reactive oxygen species (ROS) in whole blood, the expression of surface molecules by blood phagocytes and complement activity in the plasma were determined. A cDNA microarray analysis of leukocyte RNA profile of genes was performed related to the inflammatory response. Activation of the complement was already observed at the beginning of CPB. This was followed by an increase in the neutrophil number and in both spontaneous and opsonized zymosan-activated ROS production after the onset of reperfusion. The activation of blood phagocytes was affirmed by changes in surface receptors involved in the adhesion and migration of leukocytes (CD11b, CD62L and CD31). Gene arrays also confirmed the activation of leukocytes 4 h after reperfusion. In conclusion, open heart surgery with a cardiopulmonary bypass was found to be associated with a rapid and pronounced activation of blood phagocytes and complement activation which was partly independent at the onset of CPB.

Aggressive Control of Intraoperative Blood Glucose Concentration

Aggressive Control of Intraoperative Blood Glucose Concentration

Monocyte function-associated antigen expression during and after pediatric cardiac surgery

Systemic inflammatory response syndrome and infectious complications are major causes of morbidity and mortality after cardiopulmonary bypass. Recent work in adult patients suggests that the balance between proinflammatory and anti-inflammatory mediators is important. We hypothesized that the expression of different function-related receptors on circulating monocytes might reflect the net response of the inflammatory reaction. We performed a prospective and observational study in a tertiary pediatric cardiac center in a population of children (n = 40) undergoing elective cardiac surgery. Expression of receptors on the surface of monocytes was assessed before, during, and after surgical intervention. Early monocyte activation was demonstrated by changes of the expression of the chemokine receptor CCR2, which was inversely correlated with plasma levels of monocyte chemotactic protein 1 (rho = -0.54, P = .002). High levels of monocyte chemotactic protein 1 were found in children with high expression of the adhesion receptor CD11b/CD18 on circulating monocytes. The intensity of human leukocyte antigen DR expression rapidly decreased in all children after the onset of cardiopulmonary bypass ( P < .001). Low human leukocyte antigen DR expression was correlated with increased plasma levels of interleukin 10 postoperatively. Children who had signs of bacterial pneumonia postoperatively had lower levels of human leukocyte antigen DR expression before surgical intervention (relative risk, 13.3; P = .007). The expression of monocyte function-related receptors is altered after cardiac surgery. Early activation of monocytes by monocyte chemotactic protein 1 possibly released from the heart is followed by an anti-inflammatory response with suppression of monocyte human leukocyte antigen DR expression. The increased risk of bacterial infection after pediatric cardiac surgery can be anticipated by surveillance of monocyte function before surgical intervention.

Evaluation of Plasma Fentanyl Concentrations in Infants During Cardiopulmonary Bypass With Low-Volume Circuits

The purpose of the study was to measure changes in plasma fentanyl concentrations during infant cardiac surgery using a bypass circuit with low priming volume and to examine the relation of plasma fentanyl concentration and temperature to Bispectral Index (BIS) as an index of conscious level during infant cardiac surgery. Prospective cohort study. Tertiary care, academic children's hospital. Fifteen neonates and infants undergoing cardiac surgery with hypothermic cardiopulmonary bypass (CPB). Patients were anesthetized with fentanyl, receiving a 30 microg/kg bolus for induction immediately followed by continuous infusion of 0.3 microg/kg/min until skin closure. Intraoperative data and total plasma fentanyl concentration were measured at preinduction; 30 minutes postinduction; sternotomy; aortic cannulation; at 4, 30, and 60 minutes on CPB; and at 1 and 30 minutes off CPB. At the onset of CPB, fentanyl declined from 15 +/- 6 to 11 +/- 5 ng/mL (p < 0.01), increasing to 16 +/- 5 ng/mL (p < 0.01) at 30 minutes on CPB and maintaining a similar level until 30 minutes off CPB. BIS decreased from 88 +/- 20 to 42 +/- 11 (p = 0.02) with induction, declined further during cooling to 9 +/- 11 at the nadir temperature ( p < 0.001), and increased during rewarming to 29 +/- 9 at 1 minute (p < 0.001) and 35 +/- 10 at 30 minutes off CPB ( p < 0.01). Because of wide individual variation in BIS, there was no significant correlation between fentanyl and BIS and temperature. There was minimal variability in the plasma fentanyl concentration using a low-volume bypass circuit and constant infusion of fentanyl during surgery. There appears to be minimal utility for using BIS during infant cardiac surgery with no relationship between fentanyl concentration, temperature, and BIS established.

Effects of Ischemic Preconditioning in Human Heart

The aim of this study is to investigate the effects of ischemic preconditioning (IP) on myocardium and the level of nitric oxide (NO) in patients undergoing aorta-coronary bypass surgery. Twenty consecutive patients with coronary artery disease were subjected into two equal groups; the IP group and the control group. Following the onset of cardiopulmonary bypass in the study group, hearts were preconditioned with two 3-minute periods of cross-clamping separated by 2 minutes of reperfusion. In the control group, cardiopulmonary bypass was continued for 10 minutes without using cross-clamp. Arterial and coronary sinus blood samples were used to determine serum NO, malondialdehyde (MDA), creatine phosphokinase-MB (CKMB), and lactate dehydrogenase (LDH) levels. Need for defibrillation after cross-clamp removal, ECG changes, postoperative arrhythmias, ejection fraction, and fractional shortening rates were recorded as hemodynamic data. Serum NO level was higher in the study group 5 minutes after aortic clamp removal (199.3 +/- 92.7 vs. 112.2 +/- 35.8 micromol; p = 001). Serum MDA (2.55 +/- 0.4 vs. 4.06 +/- 0.5; etamol/ml; 5 minutes after the aortic clamp removal; p = 0.0002); CK-MB (22.8 +/- 2.5 vs. 37.4 +/- 4.1; U/L 12 hours after the operation, p < 0.0001), and LDH (501.8 +/- 46.7 vs. 611.4 +/- 128.3; IU/L 48 hours after the operation, p = 0.02) levels were significantly lower in the preconditioned group when compared with the control group. Also, need for electrical defibrillation was significantly lower in the study group; Ejection fraction (64.3 +/- 6.3 vs. 57.6 +/- 7.6; p = 0.04) and fractional shortening (31.7 +/- 3.9 vs. 26.2 +/- 4.0; p = 0.04) rates were better in the study group postoperatively. These data may suggest that cardioprotection by ischemic preconditioning offers higher NO production, a lower myocardial ischemia, and better functional recovery of the hearts in coronary artery surgery patients.