Nonpulsatile cardiopulmonary bypass disrupts the flow-metabolism couple in the brain

The effect of cardiopulmonary bypass on the relationship between brain glucose consumption and regional blood flow is unknown. We measured this relationship in pigs subjected to 3 hours of pulsatile or nonpulsatile cardiopulmonary bypass at normothermia and compared the results to the relationship established in a control group of pigs. A total of 10 regions were sampled in both hemispheres of the porcine brain. In control pigs, cerebral blood flow averaged 46 ml/100 gm and the glucose consumption, 21 mumol/100 gm/min. The ratio between blood flow and glucose consumption was close to 2 ml/mumol in all regions. In pulsatile cardiopulmonary bypass both the whole-brain average and the regional values declined, so that the ratio remained the same, about 2 ml/mumol. In nonpulsatile cardiopulmonary bypass regional blood flow remained normal; the average was 49 ml/100 gm/min, whereas the average glucose consumption declined to 16 mumol/100 gm. In regions with high blood flow rates, the ratio between blood flow and glucose consumption increased to about 3 ml/mumol, indicating perfusion in excess of metabolic demand. We conclude that nonpulsatile cardiopulmonary bypass at normothermia affects the metabolic flow regulation in the brain by interfering with the myogenic contractility of cerebral arterioles.     

Endothelial dysfunction in cerebral microcirculation during hypothermic cardiopulmonary bypass in newborn lambs

Objectives: Inflammatory stimuli or mechanical stresses associated with hypothermic cardiopulmonary bypass could potentially impair cerebrovascular function, resulting in inadequate cerebral perfusion. We hypothesize that hypothermic cardiopulmonary bypass is associated with endothelial or vascular smooth muscle dysfunction and associated cerebral hypoperfusion. Therefore we studied the cerebrovascular response to endothelium-dependent vasodilator, acetylcholine, endothelium-independent nitric oxide donor, sodium nitroprusside, and vasoactive amine, serotonin, in newborn lambs undergoing hypothermic cardiopulmonary bypass (nasopharygeal temperature = 18° C). Methods: Studies were performed on 13 newborn lambs equipped with a closed cranial window, allowing for direct visualization of surface pial arterioles. Six animals were studied while undergoing hypothermic cardiopulmonary bypass, whereas seven served as nonbypass, warm (37° C) controls. Pial arteriolar caliber (range = 111 to 316 μm diameter) was monitored using video microscopy. Results: Topical application of acetylcholine caused a dose-dependent increase in arteriolar diameter in the control group that was absent in animals undergoing hypothermic cardiopulmonary bypass. Hypothermic cardiopulmonary bypass did not alter the vasodilation in response to sodium nitroprusside. Furthermore, the contractile response to serotonin was fully expressed during hypothermic cardiopulmonary bypass. Conclusions: The specific loss of acetylcholine-induced vasodilation suggests endothelial cell dysfunction rather than impaired ability of vascular smooth muscle to respond to nitric oxide. It is speculated that loss of endothelium-dependent regulatory factors in the cerebral microcirculation during hypothermic cardiopulmonary bypass may enhance vasoconstriction, and impaired cerebrovascular function may be a basis for associated neurologic injury during or after hypothermic cardiopulmonary bypass. (J thorac Cardiovasc Surg 1998;15:1047-54)     

Effect of sialyl Lewis(x) oligosaccharide on myocardial and cerebral injury in the pig

BACKGROUND: Although administration of the sialyl Lewis(x) oligosaccharide may reduce myocardial injury after ischemia-reperfusion, its effect on coronary and cerebral microvascular regulation and its clinical application during cardiac operation have not been examined. METHODS: Pigs were placed on normothermic cardiopulmonary bypass after 30 minutes of left anterior descending coronary artery occlusion. The hearts were then arrested with cold high potassium cardioplegia. After 1 hour the cross-clamp was removed and the pigs were weaned from cardiopulmonary bypass and perfused for an additional 1 hour. CY-1503 (a sodium salt of the sialyl Lewis(x) oligosaccharide, n = 6) was administered before reperfusion. Six other pigs received saline vehicle. Endothelium-dependent relaxation of precontracted coronary and brain arterioles (70 to 180 microm) to adenosine 5'-diphosphate and endothelium-independent relaxation to sodium nitroprusside were studied in vitro with videomicroscopy. Control values were obtained from uninstrumented pigs. Myeloperoxidase activity in the myocardium and brain was measured to quantify neutrophil infiltration. Cardiac function and perfusion were assessed by left ventricular systolic pressure, maximum rate of increase of left ventricular pressure, left anterior descending coronary artery blood flow and percent segmental shortening, and cerebral vascular resistance, internal carotid artery blood flow, and the constitutively expressed and inducible isoform of nitric oxide synthase mRNA were measured. RESULTS: The impaired myocardial contractile function after ischemia and cardioplegia was not improved by administration of CY-1503. The reduced endothelium-dependent relaxation responses of coronary and brain arterioles during ischemia followed by cardioplegia and cardiopulmonary bypass were improved with CY-1503, but the altered pattern of organ perfusion was not improved. Myeloperoxidase activity was increased in the heart after ischemia-cardioplegia and in the brain after cardiopulmonary bypass. CY-1503 reduced myeloperoxidase activity in both the myocardium and in the brain. Expressions of myocardial inducible isoform or constitutively expressed nitric oxide synthase were not altered in the heart. CONCLUSIONS: Although the sialyl Lewis(x) oligosaccharide does reduce neutrophil infiltration and endothelial injury in the coronary and cerebral microcirculation after cardiopulmonary bypass, it does not have significant beneficial acute effects on organ perfusion or function in the myocardium or brain.     

Cerebral microembolism during cardiopulmonary bypass. Retinal microvascular studies in vivo with fluorescein angiography

To observe microembolic events in the central nervous system during cardiopulmonary bypass, we subjected 21 patients undergoing elective coronary operations to retinal fluorescein angiograms 5 minutes before cardiopulmonary bypass was discontinued. Patients with diabetes or clinically evident cerebrovascular disease were excluded. Bubble oxygenation and nonpulsatile perfusion were used for bypass. After 31 to 167 minutes of cardiopulmonary bypass, all 21 (100%) patients had retinal microvascular occlusions indicative of microembolism. Control fluorescein angiograms obtained preoperatively and in five patients immediately before bypass but after aortic cannulation showed retinal perfusion. During bypass there was a mean of 3.5 (range 1 to 7) blocked arterioles of less than 50 micron caliber and a mean of 6.3 (range 1 to 10) focal areas of capillary nonperfusion per 30-degree field of retina centered on the macula per patient. Repeat studies 30 minutes after discontinuation of bypass showed partial reperfusion with occlusions in four of the five (80%) patients and a decrease in the mean total microembolic count from 12.6 to 4.8 (38%). In later studies at a median of 8 days postoperatively, only two of 16 (12.5%) patients had persistently occluded retinal vessels. The total microembolic count did not correlate with bypass time (r = 0.14) and was not reduced by arterial line filtration with a Pall 40 micron filter (Ultipore) in a subgroup of 11 patients. Twenty patients completed four standardized psychometric tests. Retinal microvascular occlusions were more numerous in those patients with a psychometric deficit (n = 7) than in those with no deficit (n = 13; p = 0.075). In a dog model of cardiopulmonary bypass, eight of nine (88.9%) had retinal microvascular occlusions after 10 to 90 minutes of bypass. Retinal histologic studies revealed intravascular platelet-fibrin microaggregates 20 to 70 micron in diameter and focal ischemic changes in seven of the nine (77.8%) dogs. Six dogs undergoing sham bypass had normal retinal perfusion and histologic findings. This study demonstrates a very high incidence of microvascular occlusions in the territory of the internal carotid artery during bypass consistent with a microembolic origin. The clinical significance of these findings is uncertain.     

Critical oxygen delivery: the crux of bypass with a special look at the microcirculation

The microcirculation can be defined as those vascular structures where respiratory gas flux occurs. These are generally the arterioles, venules, and capillaries. Larger vascular conduits tend to have thicker walls, are at considerable distance from cellular sites of oxygen utilization, and therefore contribute little to oxygen flux. The microcirculation is complex, not a simple straight line of parallel groups of pipes with unidirectional flow. Rather, the complex network has most vascular structures not open (held in reserve) and often has bidirectional flow. Understanding the movement of O2, CO2, and other gases within this network has only recently been the center of focused research. The cardiopulmonary bypass machine is meant to keep the microcirculation normal, but research is demonstrating major changes within. This review looks at what is known today in spontaneously perfusing animals as well as early findings noting differences in cardiopulmonary bypass. We, as yet, do not understand all the mechanisms involved in the changes of the microcirculation so thoughts regarding future areas for research are discussed.     

Effect of temperature and cardiopulmonary bypass on the pharmacokinetics of remifentanil

Sixteen patients undergoing coronary revascularization requiring cardiopulmonary bypass received remifentanil 2 micrograms kg-1 or 5 micrograms kg-1 by infusion over 1 min after sternotomy but before commencing cardiopulmonary bypass, during hypothermic cardiopulmonary bypass and during cardiopulmonary bypass after rewarming. Hypothermic cardiopulmonary bypass reduced the clearance of remifentanil by an average of 20%, and this was attributed to the effect of temperature on blood and tissue esterase activity. Reductions in arterial pressure occurred with administration of both doses during normothermia only.      

Increased airway mucins after cardiopulmonary bypass associated with postoperative respiratory complications in children

OBJECTIVE: Airway mucins may play an important role in the mechanism of respiratory complications after cardiopulmonary bypass in infants and children. Our aim was to measure airway mucin levels before and after cardiopulmonary bypass and to determine whether changes in mucin levels were associated with the development of respiratory complications. METHODS: Airway glycoprotein and mucins (MUC5AC, MUC5B, and MUC2) in serial small-volume airway lavage samples from 39 young children who underwent cardiac operations with cardiopulmonary bypass were measured by slot-blot assay with specific antimucin peptide antibodies. The relationship between mucin changes and post-cardiopulmonary bypass respiratory complications was investigated. Airway lavage samples were also collected from 11 children before and after operation without cardiopulmonary bypass, and changes in mucin levels were compared with those in subjects who underwent cardiopulmonary bypass. Airway lavage sample DNA was also measured to investigate the relationship between mucin changes and lung injury. RESULTS: Glycoprotein, MUC5AC, and MUC5B levels were significantly increased after cardiopulmonary bypass (P <.001) whereas MUC2 level was not. Children with respiratory complications showed significantly higher glycoprotein and MUC5AC levels than did children without respiratory complications before and after cardiopulmonary bypass (P <.05). Increase of total mucin (MUC5AC, MUC5B, and MUC2) during cardiopulmonary bypass showed positive correlation with DNA increase during cardiopulmonary bypass (r = 0.73), PaCO(2) (r = 0.62) and alveolar-arterial oxygen difference (r = 0.55) immediately after cardiopulmonary bypass. Increase of total mucin was associated with postoperative respiratory complications and their severity. There were no significant changes detected in airway mucin during operations without cardiopulmonary bypass. CONCLUSIONS: Airway mucins were increased during cardiopulmonary bypass, and this increase was associated with markers of lung injury after cardiopulmonary bypass and with the development of postoperative respiratory complications.     

Xenon and the inflammatory response to cardiopulmonary bypass in the rat

OBJECTIVE: The purpose of this study was to investigate the effect of xenon on the inflammatory response to cardiopulmonary bypass. DESIGN: Prospective, randomized experimental study. SETTING: University research laboratory. PARTICIPANTS: Sprague-Dawley rats. INTERVENTIONS: After surgical preparation, rats were randomly divided into 4 groups: (1) SHAM rats were cannulated but did not undergo cardiopulmonary bypass; (2) cardiopulmonary bypass rats were subjected to 60 minutes of cardiopulmonary bypass using an oxygenator receiving a 30% O(2), 65% N(2), and 5% CO(2) gas mixture; (3) MK801 rats received MK801 (0.15 mg/kg intravenous) 15 minutes before 60 minutes of cardiopulmonary bypass with the same gas mixture; and (4) xenon rats underwent 60 minutes of cardiopulmonary bypass receiving a 30% O(2), 60% xenon, 5% N(2), and 5% CO(2) gas mixture. MEASUREMENTS AND MAIN RESULTS: All bypass groups showed elevations in both cytokines compared with the SHAM-operated group. However, the inflammatory response to cardiopulmonary bypass in the group receiving xenon was no different from the other bypass groups. CONCLUSIONS: Xenon appears to have no effect on the inflammatory response to cardiopulmonary bypass, making its previously described neuroprotective effect during cardiopulmonary bypass likely independent of any inflammation modulation.     

A comparison of the effects on bispectral index of mild vs. moderate hypothermia during cardiopulmonary bypass

BACKGROUND AND OBJECTIVE: Bispectral Index correlates with depth of hypnosis in adult patients. Bispectral index monitoring has been separately examined and validated during both mild and moderate hypothermic cardiopulmonary bypass. However, the effect on bispectral index of these two differing cardiopulmonary bypass temperature regimes has not previously been compared, particularly with the use of volatile anaesthetic agents. METHODS: Following Institutional Ethics Committee approval and informed consent, 30 patients undergoing coronary artery bypass grafting had additional bispectral index monitoring. Sixteen patients had mild hypothermic bypass (32-34 degrees C), and 14 had moderate hypothermic bypass (28-30 degrees C). Anaesthesia was standardized, and was maintained with enflurane throughout surgery. Scores were recorded at 14 specific event-related time points during surgery. RESULTS: This study has demonstrated that in this adult population, a relationship exists between bispectral index score and temperature throughout the duration of cardiac surgery, which included mild or moderate hypothermic cardiopulmonary bypass. It also demonstrated that patients which were categorized as having received moderately hypothermic cardiopulmonary bypass had lower bispectral index scores than those patients who received mild hypothermic cardiopulmonary bypass, at time points corresponding approximately with median steady-state bypass temperature, pre-re-warming and early re-warming periods. CONCLUSIONS: Moderate hypothermic cardiopulmonary bypass has lower bispectral index scores when compared to mild hypothermic cardiopulmonary bypass, at a steady state of inspired enflurane. This may reflect an actual increase in the depth of hypnosis. However, as this study did not address the physico-chemical changes of the volatile agent or the accuracy of the bispectral index algorithm at lower temperatures, we would not advocate a change in practice based solely on this report.     

Conscious cardiac surgery with cardiopulmonary bypass using thoracic epidural anesthesia without endotracheal general anesthesia

OBJECTIVE: The purpose of this study was to evaluate the feasibility of thoracic epidural anesthesia as an alternative technique to general anesthesia in patients undergoing cardiac surgery under cardiopulmonary bypass. DESIGN: A prospective study. SETTING: Tertiary referral heart hospital. PARTICIPANTS: Eleven patients underwent cardiac surgical procedures requiring cardiopulmonary bypass under thoracic epidural anesthesia from February to April 2004. INTERVENTIONS: An epidural catheter was inserted at C7 to T2 intervertebral space on the day before the operation. Subsequently, cardiac surgery was performed using cardiopulmonary bypass. MEASUREMENTS AND RESULTS: The midsternotomy approach was used in all the patients. Anticoagulation was achieved with 300 units/kg of heparin. Under normothermic cardiopulmonary bypass, 6 patients underwent closure of atrial septal defect, 3 underwent valve replacements, and 2 underwent coronary artery bypass surgery combined with valve replacements. Soon after establishing cardiopulmonary bypass, all but 1 patient developed apnea, which was reversed after termination of cardiopulmonary bypass. The mean cardiopulmonary bypass time was 102 +/- 28 minutes, the aortic cross-clamp time was 58 +/- 28 minutes, and the total duration of surgery was 229 +/- 64 minutes. There was no mortality or morbidity in this series. CONCLUSION: Cardiac surgical procedures requiring cardiopulmonary bypass may be performed under thoracic epidural anesthesia, without endotracheal general anesthesia.     

Superior myocardial protection with nicorandil cardioplegia.

OBJECTIVE: The ATP-sensitive potassium channel (K(ATP)) activator nicorandil used as cardioplegic agent may protect the left ventricle during cardiac arrest. Nicorandil in cold blood was compared with standard hyperkalemic blood and crystalloid cardioplegia. METHODS: Twenty-one pigs were randomly assigned to three groups: (1) cold hyperkalemic crystalloid (n=7); (2) cold hyperkalemic blood (n=7); and (3) nicorandil as cardioplegia in cold blood (n=7). Left ventricular mechanical performance, pressure-volume area (PVA) and myocardial oxygen consumption (MVO(2)) were measured before and at 1 and at 2 h after 60 min of cold global ischemia on cardiopulmonary bypass using intraventricular pressure-volume conductance catheters, coronary flow probes and O(2)-content difference. RESULTS: The slope (M(w)) of the stroke work end-diastolic volume relationship, the preload recriutable stroke work relationship, was unchanged after ischemia in the nicorandil group, but was reduced to averaged 62.5% (standard deviation 14) of baseline values in both hyperkalemic perfusions (P<0.05). The slope of the MVO(2)-PVA relationship was unchanged after nicorandil cardioplegia while the slope after hyperkalemic blood and crystalloid cardioplegia increased with 33% (P<0.02) and 52% (P<0.02) of baseline values, respectively. CONCLUSIONS: Nicorandil as sole cardioplegic agent in cold blood given intermittently preserves left ventricular contractility and myocardial energetics significantly better than traditional forms of cardioplegia after cardiac arrest.     

Therapeutic strategy of perioperative use of percutaneous cardiopulmonary bypass support (PCPS) for adult cardiac surgery.

SUBJECT AND METHOD: Percutaneous cardiopulmonary bypass support is beneficial for patients with circulatory collapse. However, therapeutic strategies of percutaneous cardiopulmonary bypass support for post-cardiotomy LOS have not been determined. We reviewed 9 patients undergoing cardiac surgery and treated with percutaneous cardiopulmonary bypass support to determine an adequate strategy for perioperative use of percutaneous cardiopulmonary bypass support. Patients included 8 males and 1 female with a mean age of 56.4 +/- 3.9 years. Six patients with IHD underwent CABG for 5 and CABG + MVR for 1 patient and 3 patients with valvular disease underwent AVR, AVR + MVR, and Ross operation respectively. Indication for percutaneous cardiopulmonary bypass support was post-cardiotomy LOS in 7 and preoperative cardiogenic shock in 2 patients. All patients underwent IABP associated with percutaneous cardiopulmonary bypass support. Systemic blood pressure was regulated to 100-120 mmHg by percutaneous cardiopulmonary bypass support flow and with minimum inotropic supports. RESULTS: Six of 9 patients (66.7%) were weaned from percutaneous cardiopulmonary bypass support and 5 patients were discharged. Five of 6 patients (83.3%) with IHD were weaned from percutaneous cardiopulmonary bypass support compared to 1 of 3 patients (33.3%) (p = 0.134) with valvular disease. Hemodynamic conditions in patients weaned from percutaneous cardiopulmonary bypass support were markedly improved within 40 hours of the introduction of percutaneous cardiopulmonary bypass support (mean percutaneous cardiopulmonary bypass support running time: 23.9 +/- 5.5 hrs). In contrast, those unable to be weaned from percutaneous cardiopulmonary bypass support (mean percutaneous cardiopulmonary bypass support running time: 84.3 +/- 6.3 hrs) showed no improvement and developed major complications such as cerebral damage or multiorgan failure. CONCLUSIONS: Perioperative use of percutaneous cardiopulmonary bypass support may be more effective for patients undergoing coronary artery surgery. Limited use of percutaneous cardiopulmonary bypass support within 48 hours may be applicable for post-cardiotomy patients.     

Therapeutic strategy of perioperative use of percutaneous cardiopulmonary bypass support (PCPS) for adult cardiac surgery

Subject and method: Percutaneous cardiopulmonary bypass support is beneficial for patients with circulatory collapse. However, therapeutic strategies of percutaneous cardiopulmonary bypass support for post-cardiotomy LOS have not been determined. We reviewed 9 patients undergoing cardiac surgery and treated with percutaneous cardiopulmonary bypass support to determine an adequate strategy for perioperative use of percutaneous cardiopulmonary bypass support. Patients included 8 males and 1 female with a mean age of 56.4 ± 3.9 years. Six patients with IHD underwent CABG for 5 and CABG + MVR for 1 patient and 3 patients with valvular disease underwent AVR, AVR + MVR, and Ross operation respectively. Indication for percutaneous cardiopulmonary bypass support was post-cardiotomy LOS in 7 and preoperative cardiogenic shock in 2 patients. All patients underwent IABP associated with percutaneous cardiopulmonary bypass support. Systemic blood pressure was regulated to 100–120 mmHg by percutaneous cardiopulmonary bypass support flow and with minimum inotropic supports.Results: Six of 9 patients (66.7%) were weaned from percutaneous cardiopulmonary bypass support and 5 patients were discharged. Five of 6 patients (83.3%) with IHD were weaned from percutaneous cardiopulmonary bypass support compared to 1 of 3 patients (33.3%) (p=0.134) with valvular disease. Hemodynamic conditions in patients weaned from percutaneous cardiopulmonary bypass support were markedly improved within 40 hours of the introduction of percutaneous cardiopulmonary bypass support (mean percutaneous cardiopulmonary bypass support running time: 23.9 ± 5.5 hrs). In contrast, those unable to be weaned from percutaneous cardiopulmonary bypass support (mean percutaneous cardiopulmonary bypass support running time: 84.3 ± 6.3 hrs) showed no improvement and developed major complications such as cerebral damage or multiorgan failure.Conclusions: Perioperative use of percutaneous cardiopulmonary bypass support may be more effective for patients undergoing coronary artery surgery. Limited use of percutaneous cardiopulmonary bypass support within 48 hours may be applicable for post-cardiotomy patients.     

Comparison of two technics of cardiopulmonary bypass (conventional and mini CPB) in the trans-and postoperative periods of cardiac surgery

Objective

This study aimed to compare the effects of two different perfusion techniques: conventional cardiopulmonary bypass and miniature cardiopulmonary bypass in patients undergoing cardiac surgery at the University Hospital of Santa Maria - RS.

Methods

We perform a retrospective, cross-sectional study, based on data collected from the patients operated between 2010 and 2013. We analyzed the records of 242 patients divided into two groups: Group I: 149 patients undergoing cardiopulmonary bypass and Group II - 93 patients undergoing the miniature cardiopulmonary bypass.

Results

The clinical profile of patients in the preoperative period was similar in the cardiopulmonary bypass and miniature cardiopulmonary bypass groups without significant differences, except in age, which was greater in the miniature cardiopulmonary bypass group. The perioperative data were significant of blood collected for autotransfusion, which were higher in the group with miniature cardiopulmonary bypass than the cardiopulmonary bypass and in transfusion of packed red blood cells, which was higher in cardiopulmonary bypass than in miniature cardiopulmonary bypass. In the immediate, first and second postoperative period the values of hematocrit and hemoglobin were higher and significant in miniature cardiopulmonary bypass than in the cardiopulmonary bypass, although the bleeding in the first and second postoperative days was higher and significant in miniature cardiopulmonary bypass than in the cardiopulmonary bypass.

Conclusion

The present results suggest that the miniature cardiopulmonary bypass was beneficial in reducing the red blood cell transfusion during surgery and showed slight but significant increase in hematocrit and hemoglobin in the postoperative period.     

Effects of normothermic cardiopulmonary bypass on bispectral index

This study investigated the changes in the hypnotic component of anaesthesia, estimated by the bispectral index of the electroencephalogram, during normothermic cardiopulmonary bypass. Twenty-six patients (20 men, 6 women), aged 61 +/- 11 years (Mean +/- SD) scheduled for cardiac surgery were premedicated with hydroxyzine and meperidine. Anaesthesia was induced and maintained with a computer-controlled continuous infusion (not adjusted for haemodilution) of sufentanil (effect site concentration 0.4-0.6 ng mL-1) and a manually adjusted continuous infusion of propofol (4.4 +/- 1.8 mg kg-1 h-1). Cardiopulmonary bypass was normothermic with moderate haemodilution. Bispectral index was measured with a referential montage before, 30 s, 1, and 3 min after cardiopulmonary bypass onset, before and after aortic cross-clamping, 30 min after cardiopulmonary bypass onset, before and after aorta cross-clamp release and before and after weaning from cardiopulmonary bypass. Bispectral index values were 48 +/- 8 before cardiopulmonary bypass onset, 50 +/- 10 before, and 48 +/- 8 after end of cardiopulmonary bypass (P = NS). No patient had increases in bispectral index values during cardiopulmonary bypass consistent with awakening. We conclude that with the anaesthetic regimen presented in this study bispectral index values do not change during normothermic cardiopulmonary bypass.     

Influence of diabetes on mortality and morbidity: off-pump coronary artery bypass grafting versus coronary artery bypass grafting with cardiopulmonary bypass

BACKGROUND: Myocardial revascularization in diabetic patients is challenging with no established optimum treatment strategy. We reviewed our coronary artery bypass grafting experience to determine the impact of eliminating cardiopulmonary bypass on outcomes in diabetic patients relative to nondiabetic patients. METHODS: From January 1995 through December 1999, 9,965 patients, of whom 2,891 (29%) had diabetes, underwent isolated coronary artery bypass grafting. Diabetic and nondiabetic patients were further divided into groups on the basis of cardiopulmonary bypass use. Twelve percent (346 of 2,891) of diabetic patients and 12% (829 of 7,074) of nondiabetic patients underwent coronary artery bypass grafting without cardiopulmonary bypass; the remainder had coronary artery bypass grafting with cardiopulmonary bypass. Nineteen preoperative variables were compared among treatment groups by univariate analysis. RESULTS: Patients undergoing coronary artery bypass grafting without cardiopulmonary bypass compared with those having coronary artery bypass grafting with cardiopulmonary bypass had higher mean predicted mortalities (diabetic, 3.96% versus 3.72%, p = 0.83; nondiabetic, 3.03% versus 2.86%, p = 0.79). In nondiabetic patients, coronary artery bypass grafting without cardiopulmonary bypass provides an actual and risk-adjusted survival advantage over coronary artery bypass grafting with cardiopulmonary bypass (1.81% versus 3.44%, p = 0.0127; risk-adjusted mortality, 1.79% versus 3.61%, p = 0.007). This survival benefit of coronary artery bypass grafting without cardiopulmonary bypass was not seen in diabetic patients (2.89% versus 3.69%, p = 0.452; risk-adjusted mortality, 2.19% versus 2.98%, p = 0.42). Diabetic patients undergoing coronary artery bypass grafting without cardiopulmonary bypass had fewer complications, including decreased blood product use (34.39% versus 58.4%, p = 0.001), and reduced incidence of prolonged ventilation (6.94% versus 12.10%, p = 0.005), atrial fibrillation (15.90% versus 23.26%, p = 0.002), and renal failure requiring dialysis (0.87% versus 2.75%, p = 0.036). CONCLUSIONS: The survival advantage in nondiabetic patients treated with coronary artery bypass grafting without cardiopulmonary bypass is not apparent in diabetic patients. Coronary artery bypass grafting without cardiopulmonary bypass in diabetic patients is nevertheless associated with a significant reduction in morbidity.     

Myocardial protection by nicorandil during open-heart surgery under cardiopulmonary bypass

BACKGROUND: To evaluate the myocardial protective effect of nicorandil when used as an adjuvant to cold hyperkalaemic cardioplegia in open-heart surgery. METHODS: Patients who underwent surgery under cardiopulmonary bypass (CPB) for mitral valve replacement (MVR, 23 patients) or coronary artery bypass grafting (CABG, 24 patients) were entered in a double-blind study. The patients were randomized to a nicorandil Group (N) or placebo Group (P). Nicorandil 0.1 mg kg-1 (Group N), or normal saline (Group P), were administered at three time points: (1) after aortic cannulation, but prior to going on CPB, (2) 5 min before aortic cross-clamping and (3) 5 min before reperfusion. The following variables were studied: (a) time until electromechanical arrest after cardioplegia administration (Tarrest), (b) time until return of electromechanical activity after aortic cross-clamp removal (Trecovery), (c) incidence of postoperative myocardial infarction or low output syndromes (d) dysrhythmias requiring intervention after aortic cross-clamp removal and (e) haemodynamic changes after nicorandil administration. RESULTS: The Tarrest after cardioplegia administration was significantly faster in nicorandil group in both MVR and CABG patients (P 75 IU L-1 in MVR patients was significantly lower in the Group N than in placebo patients (P < 0.05). However, in CABG patients there was no such significant difference. The incidence of dysrhythmias requiring intervention after aortic cross-clamp removal was also less in Group N. Administration of 0.1 mg kg-1 boluses of nicorandil did not cause significant haemodynamic changes or precipitate dysrhythmias in any patient. CONCLUSION: Nicorandil enhances the myocardial protective effect of cold hyperkalaemic cardioplegia in cardiac surgery patients.     

The effects of methylprednisolone on complement, immunoglobulins and pulmonary neutrophil sequestration during cardiopulmonary bypass.

In this study, the authors administered high dose (30 mg/kg body weight i.v.) methylprednisolone before cardiopulmonary bypass to observe the effects on complement, immunoglobulins and pulmonary neutrophil sequestration. Fifty patients undergoing valve replacements were included in this study. Patients were divided into two groups: group I (20 patients) served as control and did not receive methylprednisolone, group II (30 patients) received methylprednisolone. Blood samples for complements (C3c and C4) were taken, before cardiopulmonary bypass, at 5, 10 and 30 min intervals from the end of cardiopulmonary bypass, after reversal of heparin with protamine infusion, and after skin closure. Blood samples for immunoglobulins were taken before cardiopulmonary bypass, 30 min after onset of cardiopulmonary bypass and after skin closure. After onset of cardiopulmonary bypass, all C3c and C4 levels decreased in both groups. There was a significant decrease in C4 levels at end of cardiopulmonary bypass and after protamine infusion in group I compared with group II (P < 0.05). C3c levels in group I decreased significantly compared with group II after 30 min of cardiopulmonary bypass and after protamine infusion (P < 0.05). All immunoglobulin (IgG, IgM, IgA) levels were decreased in both groups, but the decrease in IgG was statistically significant after skin closure in group I compared with group II (P < 0.05). Pulmonary neutrophil sequestration was higher in the control group compared with the methyl-prednisolone group (P < 0.05). In conclusion, methylprednisolone administration before cardiopulmonary bypass may prevent the harmful effects of complement activation, immunoglobulin denaturation and neutrophil sequestration in the pulmonary capillary system.     

Transit time flow measurement in on-pump and off-pump coronary artery surgery

OBJECTIVE: Transit time flow measurement is frequently used during coronary artery bypass with and without cardiopulmonary bypass to detect graft dysfunction resulting from technical errors. METHODS: Intraoperative transit time flow measurement measurements of 896 patients requiring surgery for double- or triple-vessel disease were reviewed retrospectively. Six-hundred and ninety-five patients were operated on-pump (Group A: coronary artery bypass with cardiopulmonary bypass), and 201 patients off-pump (Group B: coronary artery bypass without cardiopulmonary bypass). Transit time flow measurement measurements were analyzed for mean flow (mL/min). In total, measurements of 2247 grafts were analyzed. RESULTS: Transit time flow measurement flows were lower in coronary artery bypass without cardiopulmonary bypass patients (left internal thoracic artery to left anterior descending artery: Group A, 37 [31, 40] mL/min vs Group B, 24 [20, 26] mL/min; saphenous vein graft to left anterior descending artery: Group A, 46.5 [40, 56] mL/min vs Group B, 21 [14, 57] mL/min. Troponin I release was reduced in the coronary artery bypass without cardiopulmonary bypass patients, with median values of 7.8 [7.0, 8.3] microg/L in Group A and 1.2 [0.9, 2.3] microg/L in Group B. CONCLUSION: Evaluation of transit time flow measurement is valuable in determining coronary graft patency after coronary artery bypass with cardiopulmonary bypass and coronary artery bypass without cardiopulmonary bypass. Decreased troponin I release suggests a myocardial benefit of coronary artery bypass without cardiopulmonary bypass compared to coronary artery bypass with cardiopulmonary bypass, although the intraoperative transit time flow measurement flow measurements are markedly lower.     

Clinical outcome after cardiac operations in patients with cirrhosis

BACKGROUND: To evaluate the clinical outcome after cardiac operations in patients with cirrhosis, a retrospective study was undertaken. METHODS: Between 1989 and 2003, 18 patients with cirrhosis who underwent cardiac operations were identified. Their preoperative status and postoperative clinical results were assessed. RESULTS: Ten patients were classified as having Child-Pugh class A cirrhosis, 7 as having class B cirrhosis, and 1 as having class C cirrhosis. Fifteen of 18 patients underwent cardiac surgery using cardiopulmonary bypass, and the remaining 3 patients with class B cirrhosis received coronary artery bypass grafting without cardiopulmonary bypass. In patients undergoing cardiopulmonary bypass, 60% of those with class A cirrhosis and 100% of those with class B cirrhosis and class C cirrhosis had postoperative major complications, including infection, respiratory failure, renal failure, bleeding, and gastrointestinal disorder. One of 3 patients (33%) with class B cirrhosis undergoing coronary artery bypass grafting without cardiopulmonary bypass had major complications. The overall postoperative mortality rate was 17%. Hospital mortality of patients with class A cirrhosis, class B cirrhosis, and class C cirrhosis undergoing cardiopulmonary bypass was 0%, 50%, and 100%, respectively. None of 3 patients with class B cirrhosis undergoing coronary artery bypass grafting without cardiopulmonary bypass died in this study. CONCLUSIONS: Although the incidence of major complications was high, patients with Child-Pugh class A cirrhosis tolerated cardiac surgery satisfactorily. Patients with more advanced cirrhosis, however, may not be suitable for elective cardiac operations with cardiopulmonary bypass. Although our results are not conclusive, coronary artery bypass grafting without cardiopulmonary bypass can be an alternative therapeutic strategy for patients with advanced cirrhosis requiring surgical revascularization.