Sex-based differences in serum cardiac troponin I, a specific marker for myocardial injury, after cardiac surgery.

BACKGROUND: Prevalence and causes of sex-based differences in morbidity and mortality secondary to cardiovascular disease remain controversial. Cardiac troponin I (cTnI) is a sensitive and specific marker for myocardial injury. Serial cTnI measurements have been used to identify perioperative myocardial cell injury. OBJECTIVE: To determine whether sex influences the extent of myocardial injury during cardiac surgery, we measured perioperative cTnI in male and female patients. DESIGN: A total of 17 male and 17 female patients were prospectively studied in an age- and case-matched manner. Arterial cTnI were obtained preinduction, 30 mins after the application of the aortic cross-clamp, at arrival to the intensive care unit, and on postoperative day 1. SETTING: Tertiary cardiac surgery center at a major teaching hospital. RESULTS: There was no difference between men and women in body mass index (kg/m2), duration of cardiopulmonary bypass, and aortic cross-clamp times. Preoperative cTnI measurements were similar in men (0.24 +/- 0.15 ng/mL) and women (0.25 +/- 0.13 ng/mL, mean +/- sem). The maximum serum cTnI occurred on postoperative day 1 in all patients, and it was 3-fold higher in men (18.5 +/- 5.7 ng/mL) compared with women (6.4 +/- 1.0 ng/mL). CONCLUSIONS: Men had markedly higher serum cTnI compared with women, although they were case matched with respect to age and cardiac risk factors. Our results may suggest there may be sex-related differences in the myocardial response to ischemia and reperfusion injury or intrinsic differences between the male and female myocardium.

Photosystem II fluorescence quenching in the cyanobacterium Synechocystis PCC 6803: involvement of two different mechanisms.

The structural changes associated to non-photochemical quenching in cyanobacteria is still a matter of discussion. The role of phycobilisome and/or photosystem mobility in this mechanism is a point of interest to be elucidated. Changes in photosystem II fluorescence induced by different quality of illumination (state transitions) or by strong light were characterized at different temperatures in wild-type and mutant cells, that lacked polyunsaturated fatty acids, of the cyanobacterium Synechocystis PCC 6803. The amplitude and the rate of state transitions decreased by lowering temperature in both strains. Our results support the hypothesis that a movement of membrane complexes and/or changes in the oligomerization state of these complexes are involved in the mechanism of state transitions. The quenching induced by strong blue light which was not associated to D1 damage and photoinhibition, did not depend on temperature or on the membrane state. Thus, the mechanism involved in the formation of this type of quenching seems to be unrelated to the movement of membrane complexes. Our results strongly support the idea that the mechanism involved in the fluorescence quenching induced by light 2 is different from that involved in strong blue light induced quenching.

Incidence of atrial fibrillation after mild or moderate hypothermic cardiopulmonary bypass.

OBJECTIVES: Atrial fibrillation remains a significant source of morbidity after coronary artery bypass grafting (CABG). Whether cardiopulmonary bypass (CPB) temperature influences the occurrence of postoperative atrial fibrillation in CABG patients has not been specifically examined. In the present study, we reviewed postoperative data from patients who were prospectively randomized to mild or moderate hypothermic CPB for elective CABG to determine the incidence of postoperative atrial fibrillation. DESIGN: Randomized, single center, observational study. SETTING: Tertiary university medical center. PATIENTS: Adults undergoing elective CABG surgery. INTERVENTIONS: Enrolled patients were prospectively randomized to mild (34 degrees C [93.2 degrees F]) or moderate (28 degrees C [82.4 degrees F]) hypothermic CPB. MEASUREMENTS AND MAIN RESULTS: The incidence of postoperative atrial fibrillation was determined by review of ICU and hospital records. There was a significantly higher incidence of atrial fibrillation in the moderate compared with the mild hypothermic CPB group. Patients who had postoperative atrial fibrillation were significantly older than those without atrial fibrillation. Furthermore, a significant increase in the relative risk of developing postoperative atrial fibrillation was found for both age and CPB temperature. CONCLUSIONS: Our results indicate that the temperature of systemic cooling during CPB is an important factor in the development of atrial fibrillation after CABG surgery. In addition, this study confirms that increasing age is a significant determinant of postoperative atrial fibrillation.

DeltapH-dependent photosystem II fluorescence quenching induced by saturating, multiturnover pulses in red algae

We have previously shown that in the red alga Rhodella violacea, exposure to continuous low intensities of light 2 (green light) or near-saturating intensities of white light induces a DeltapH-dependent PSII fluorescence quenching. In this article we further characterize this fluorescence quenching by using white, saturating, multiturnover pulses. Even though the pulses are necessary to induce the DeltapH and the quenching, the development of the latter occurred in darkness and required several tens of seconds. In darkness or in the light in the presence of 2, 5-dibromo-3-methyl-6-isopropyl-p-benzoquinone, the dissipation of the quenching was very slow (more than 15 min) due to a low consumption of the DeltapH, which corresponds to an inactive ATP synthase. In contrast, under far-red illumination or in the presence of 3-(3,4-dichlorophenyl)-1,1'-dimethylurea (only in light), the fluorescence quenching relaxed in a few seconds. The presence of N, N'-dicyclohexyl carbodiimide hindered this relaxation. We propose that the quenching relaxation is related to the consumption of DeltapH by ATP synthase, which remains active under conditions favoring pseudolinear and cyclic electron transfer.

Paediatric cardiac anaesthesia in a developing country. Guatemala Heart Team.

During the week of October 15-24, 1995 a team of 65 medical, anaesthesiology, surgical, nursing and paramedical personnel travelled to Guatemala City, Guatemala to perform cardiac surgery on children with complex congenital and acquired valvular heart disease. During this mission 42 patients had their lesions surgically repaired. Cardiopulmonary bypass was required in 36 cases. There were no anaesthetic or surgical deaths. All six patients who did not require cardiopulmonary bypass were extubated in the operating room. Of the patients who required cardiopulmonary bypass, 23 were extubated in the operating room (64%). There was no intraoperative anaesthetic morbidity nor postoperative respiratory complications. No patients was reintubated after planned extubation. Cardiac surgery in paediatric age patients can safely be performed in developing countries if close attention is paid to proper patient selection and one maintains the standards of care practised in developed countries.

Sympathetic response during cardiopulmonary bypass: mild versus moderate hypothermia.

OBJECTIVE: To determine the sympathetic response during cardiopulmonary bypass at mild (34 degrees C) and moderate (28 degrees C) hypothermia. DESIGN: A randomized study. SETTING: Tertiary university hospital. PATIENTS: Adults undergoing elective coronary artery bypass graft surgery. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Plasma norepinephrine, epinephrine, and neuropeptide Y concentrations were measured. Moderate, but not mild, hypothermic cardiopulmonary bypass evoked a significant sympathetic response with increases in plasma norepinephrine and neuropeptide Y concentrations. A significantly higher incidence of postoperative atrial fibrillation was also observed in the moderate hypothermic compared with the mild hypothermic group. CONCLUSIONS: Our results indicate that the degree of hypothermia significantly influences the sympathetic response during cardiopulmonary bypass. The higher incidence of postoperative atrial fibrillation in the moderate hypothermic group suggests that the enhanced sympathetic response might be one contributing factor in the development of atrial fibrillation.

Cerebral dysfunction after coronary artery bypass grafting done with mild or moderate hypothermia.

OBJECTIVE: Ninety-nine patients undergoing elective coronary artery bypass grafting were enrolled in a prospective, randomized study to evaluate the incidence of cerebral dysfunction after "mild" or "moderate" hypothermia during cardiopulmonary bypass. METHODS: Patients were evaluated before and after operation before hospital discharge and in some cases at follow-up at least 6 weeks later with a complete neurologic examination (85 patients) and a battery of standard neuropsychometric tests (86 patients). RESULTS: Postoperative changes detected by neurologic examination consisted of the appearance of new primitive reflexes in both groups. No statistically significant differences in incidence were found. The neuropsychometric performances of the two groups were statistically similar by either event-rate or group-rate analysis. CONCLUSIONS: There is no detectable difference in postoperative cerebral dysfunction in patients undergoing coronary artery bypass grafting who are supported by cardiopulmonary bypass with either mild or moderate hypothermia.

State transitions or delta pH-dependent quenching of photosystem II fluorescence in red algae.

Fluorescence changes attributed to state transitions have been shown to exist in phycobilisome-containing organisms. Contradictory conclusions have been derived from studies about the mechanism of state transitions carried out either in cyanobacteria or in red algae. In this paper, fluorescence changes induced by light 1 and light 2 are reinvestigated in a unicellular red alga, Rhodella violacea, by performing 77 K fluorescence spectra and fluorescence yield measurements at room temperature in the presence of uncouplers and inhibitors of the electron transfer. We show that transfer of light 1-adapted cells to light 2 (green light) induces a large quenching of photosystem II which is suppressed by subsequent incubation in light 1 (far-red or blue light). The level of the photosystem I-related fluorescence does not change during these transfers. We demonstrate that the large quenching of photosystem II induced by low intensities of green light is completely suppressed by addition of NH4Cl, an uncoupler that inhibits ATP synthesis by canceling the delta pH across the membrane. DCCD, which is an inhibitor of the ATPase that swells the delta pH, maintains the quenched state even under light 1 illumination. The opposite effects of DCMU and DBMIB on state transitions are demonstrated to be due to a suppression (by DCMU) or maintenance (by DBMIB) of the delta pH and not to change in the redox state of the plastoquinone. We conclude that, in R. violacea, the fluorescence change commonly associated with state 2 transition is in fact a delta pH-dependent quenching. This type of quenching has always been associated with near-saturating light intensities. Here, we show that very low intensities of a light that activates only the photosystem II induce a delta pH across the membrane that is not dissipated since the ATPase is not activated. The delta pH is dissipated only under conditions in which the photosystem I turns, confirming that the thioredoxin must be reduced to activate the ATPase. We suggest that the fluorescence changes, induced by various light conditions, in cyanobacteria and red algae could be associated with different phenomena.

Jugular venous bulb oxyhemoglobin saturation during cardiac surgery: accuracy and reliability using a continuous monitor.

Previous studies have demonstrated the feasibility of continuously monitoring jugular venous oxygen saturation (SjO2) with a fiberoptic catheter during hypothermic cardiopulmonary bypass (CPB). In the present study, with patients maintained at either moderate (28 degrees C) or mild (32-34 degrees C) hypothermia during CPB, SjO2 values obtained from a fiberoptic catheter were compared to intermittent samples analyzed by a co-oximeter. Twenty patients scheduled for elective coronary artery or valvular surgery had a 5.5 Fr Opticath catheter inserted into the left internal jugular bulb after induction of general anesthesia. The catheter was calibrated in vitro and in vivo according to the manufacturer's specifications. Catheter and co-oximetry SjO2 values obtained at four time points--1) pre-CPB, 2) target CPB temperature, 3) mid-rewarming, and 4) post-CPB--were compared using linear regression, Bland-Altman analysis, and Shrout-Fleiss interclass correlation coefficient analysis. These statistical methods revealed poor correlation between the catheter and co-oximetry SjO2 values: r = 0.44 by linear regression and 0.32 by interclass correlation coefficient analysis, and was unacceptably discrepant by Bland-Altman analysis. Oxyhemoglobin saturation values obtained continuously from a jugular venous bulb fiberoptic catheter during CPB may not accurately reflect true oxyhemoglobin saturation, and caution is warranted when interpreting SjO2 values obtained from a fiberoptic catheter during CPB.

Safety of repeat aprotinin administration for LVAD recipients undergoing cardiac transplantation.

BACKGROUND: Anecdotal reports of allergic and anaphylactic reactions after aprotinin therapy have raised concern that its repeat use may be associated with substantial morbidity. METHODS: To address this concern, we reviewed our experience with all patients who underwent implantation of a left ventricular assist device and subsequent cardiac transplantation with perioperative use of aprotinin. RESULTS: Twenty-three patients received full-dose aprotinin during left ventricular assist device implantation and subsequent cardiac transplantation. All patients tolerated primary exposure to aprotinin without complication. One episode of anaphylaxis after secondary exposure was treated with rapid institution of cardiopulmonary bypass. Although renal dysfunction was observed shortly after cardiac transplantation in 30.4% of patients, the effect was transient and occurred in the presence of cyclosporine. The one perioperative death after secondary exposure was unrelated to bleeding complications. No clinically evident thromboembolic events were documented. CONCLUSIONS: Primary and secondary exposure to aprotinin during operation with cardiopulmonary bypass is associated with limited intraoperative blood use, a low incidence of transient renal dysfunction and anaphylaxis, a rare need of reoperation for bleeding, and no clinical thromboembolic events.

Cerebral dysfunction after cardiac operations in elderly patients.

BACKGROUND: Cerebral injury remains a significant complication of cardiac operations. We determined the incidence of cerebral dysfunction in a population of elderly patients undergoing open chamber cardiac operations (group 1) as compared with a younger population (group 2) and an age-matched group of elderly patients undergoing major noncardiac operations (group 3). METHODS: Sixty-eight patients (55 for open chamber cardiac operations and 13 for noncardiac operations) were prospectively studied. Patients were evaluated preoperatively and postoperatively before hospital discharge using a complete neurologic examination and a battery of standard neuropsychometric tests, and at surgical follow-up with neuropsychometric tests only. RESULTS: Postoperative changes detected by neurologic examination consisted of the appearance of new primitive reflexes in all groups. No statistically significant differences in incidence were found. The neuropsychometric performance of group 1 patients was statistically different from that of patients in groups 2 and 3 only in the early follow-up period. CONCLUSIONS: Elderly patients having open chamber cardiac operations exhibit significantly more cerebral dysfunction in the early postoperative period than those undergoing major noncardiac operations and younger patients after open chamber procedures. These changes do not persist into the late follow-up period.

Noncardiac surgery in long-term implantable left ventricular assist-device recipients.

OBJECTIVE: The authors describe their experience with left ventricular assist-device (LVAD) recipients undergoing noncardiac surgery and delineate surgical, anesthetic, and logistic factors important in the successful intraoperative management of these patients. SUMMARY BACKGROUND DATA: Left ventricular assist-devices have become part of the armamentarium in the treatment of end-stage heart failure. As the numbers of patients chronically supported with long-term implantable devices grows, general surgical problems that are commonly seen in other hospitalized patients are becoming manifest. Of particular interest is the intraoperative management of patients undergoing elective noncardiac surgical procedures. METHODS: The anesthesia records and clinical charts were reviewed for eight ventricular assist-device recipients undergoing general surgical procedures between August 1, 1990 and August 31, 1994. RESULTS: A total of 12 procedures were performed in 6 men and 2 women averaging 52.7 years of age. Mean time elapsed from device implantation to operation was 68 +/- 35 days. Conventional inhalational and intravenous anesthetic techniques were well tolerated in these patients undergoing diverse surgical procedures. No perioperative mortality was observed. Five of eight patients went on to successful cardiac transplantation. CONCLUSIONS: Hemodynamic recovery after LVAD insertion has defined a new group of patients who develop noncardiac surgical problems often seen in other critically ill patients. Recognition of the unique potential problems that the LVAD recipient may encounter in the perioperative period--in particular patient positioning, device limitations, and fluid and inotropic management--will ensure an optimal surgical outcome for LVAD recipients undergoing noncardiac surgery.

The reliability of quantitative electroencephalography as an indicator of cerebral ischemia.

The electroencephalogram (EEG) has been used to detect episodes of cerebral ischemia during various surgical procedures. Recently, computerized systems for recording and interpreting the quantitative EEG (QEEG) have been used by anesthesiologists because of their ease of application, clarity of display, and reported ability to identify ischemic EEG changes. However, the extent to which automated techniques of QEEG interpretation reliably differentiate cerebral ischemia from the confounding effects of anesthetics and other sources of "artifact" is not completely established. In this study, EEGs were recorded before and after defibrillator testing in patients undergoing implantable cardioverter defibrillator (ICD) placement and during analogous time periods in control patients undergoing abdominal surgery. EEGs were subjected to standard visual inspection by an experienced electroencephalographer and QEEG analysis with a commercially available system was used for automated EEG interpretation in order to evaluate the reliability of this quantitative technique. The CIMON technique identified episodes which met previously defined criteria for QEEG cerebral dysfunction and ischemic pattern in both groups, despite the presumed absence of cerebral ischemia in the control patients. Since there was no evidence of cerebral ischemia in the raw EEGs of either the ICD patients or the controls, these QEEG changes were not confirmed by conventional techniques of EEG interpretation. Our results suggest that caution is warranted when using automated systems for intraoperative interpretation of EEG.

Implantable cardioverter-defibrillator. Evaluation of clinical neurologic outcome and electroencephalographic changes during implantation.

During placement of implantable cardioverter-defibrillators, ventricular arrhythmias are induced to test the function of the devices. Although cerebral hypoperfusion and ischemic electroencephalographic changes occur in patients while implantable cardioverter-defibrillators are being tested, no investigation has assessed neurologic outcome in these patients. Nine patients having either implantation or change of an implantable cardioverter-defibrillator underwent neurologic examination and neuropsychometric tests before and after the operation. After induction of general anesthesia and insertion of implantable cardioverter-defibrillator leads (when needed), ventricular fibrillation, ventricular flutter, or ventricular tachycardia, was induced by means of programmed electrical stimulation. Implantable cardioverter-defibrillator testing continued until satisfactory lead placement was confirmed. The intraoperative electroencephalographic recording was analyzed for evidence of ischemic change. In all, an electroencephalogram was recorded during 50 periods of circulatory arrest. Mean duration of the arrest periods was 13.6 seconds. By means of conventional visual inspection of the raw electroencephalogram, high-amplitude rhythmic delta or theta, voltage attenuation, or loss of fast frequency activity was observed in 30 of the arrests. By means of an automated technique of electroencephalographic interpretation based on power spectral analysis, electroencephalographic changes were correctly identified in 26 of the arrests. The incidence of these electroencephalographic changes was dependent on the arrest duration. The mean interval from arrest onset to electroencephalographic change was 7.5 seconds (standard deviation +/- 1.8 seconds). In patients with electroencephalographic changes during multiple arrests, no downward trend in this interval was detected in later arrests and no evidence of persistent ischemic change was observed in electroencephalograms recorded after the conclusion of implantable cardioverter-defibrillator testing. Postoperative neurologic and neuropsychometric testing was completed in eight patients, none of whom exhibited a new neurologic deficit, exacerbation of a preexisting neurologic condition, or significant deterioration in neuropsychometric performance. We conclude that the brief arrest of cerebral circulation induced during insertion of an implantable cardioverter-defibrillator is not associated with permanent neurologic injury.

Noncardiac surgery in heart transplant recipients in the cyclosporine era.

As survival and quality of life continue to improve for cardiac transplant recipients, there is an ever-increasing possibility that these patients will present for elective and/or emergency surgery outside of a transplantation center. Cyclosporine therapy has been a major factor in extending homograft survival, but recent studies have suggested that cyclosporine administration increases the duration of action of some anesthetics. The authors evaluated the influence on anesthetic management of cardiac transplantation and chronic cyclosporine therapy in a retrospective review of all postcardiac transplant patients who presented for noncardiac surgery at the study institution. The data suggest that a number of commonly used anesthetic techniques can be administered safely to these patients when no evidence of graft rejection is present. No clinically significant prolongation of anesthetic effect was encountered following the doses of anesthetics described.

Influence of temperature on in vitro metabolism of esmolol.

Esmolol has been used to improve hemodynamic stability during sternotomy and aortic manipulation for coronary artery bypass graft surgery. In order to investigate the alterations of esmolol metabolism by hypothermic cardiopulmonary bypass (CPB), the effect of temperature on the metabolism of esmolol in vitro was determined. Samples of human whole blood were combined with esmolol solution (50 micrograms/mL in 0.9 mol/L NaCl) and incubated at 4 degrees C, 15 degrees C, 25 degrees C, and 37 degrees C. Aliquots were sampled at 1, 5, 10, 15, 30, 60, and 120 minutes; esmolol concentration was determined using high-pressure liquid chromatography. There was a temperature-dependent decrease in the degradation of esmolol. The half-life for esmolol in human blood was 19.6 +/- 3.8 minutes at 37 degrees C, 47 +/- 10.1 minutes at 25 degrees C, 152 +/- 46.6 minutes at 15 degrees C, and 226.7 +/- 60.1 minutes at 4 degrees C. This study clearly shows marked reduction of esmolol metabolism with hypothermia possibly leading to persistent beta-adrenergic blockade following the discontinuation of CPB. Persistent beta-blockade may provide additional protection to the ischemic myocardium during hypothermic arrest and/or result in difficulty in weaning from CPB.

Lumbar epidural fentanyl analgesia after thoracic surgery.

Thoracic epidural fentanyl has been used successfully for postoperative analgesia in patients undergoing thoracic surgery. Prior investigators have suggested that increasing the administered dosage and volume of lumbar epidural fentanyl may increase the spread of analgesia. The feasibility of injecting a high volume (20 mL) of fentanyl into the lumbar epidural space for post-thoracic surgery analgesia was studied in 17 patients undergoing elective thoracotomy or sternotomy. All patients had a lumbar epidural catheter placed before induction of general anesthesia. No narcotic was administered during surgery. Thirty minutes before the conclusion of anesthesia, 200 micrograms of fentanyl in 16 mL of 0.9% saline was administered via the epidural route. In the intensive care unit (ICU), additional fentanyl in the same dosage and volume was injected when the patient complained of pain. Pain was scored on a linear analog scale pre-injection and 30 minutes post-injection. Arterial blood gases were obtained simultaneously. All patients experienced pain relief within 15 minutes of injection. No significant respiratory depression or hypercarbia was noted. Lumbar epidural fentanyl is a safe and practical alternative to thoracic epidural analgesia in the post-thoracic surgical patient.