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

OBJECTIVE: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.

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.

Pharmacokinetics and efficacy of ropivacaine for continuous epidural infusion in neonates and infants.

INTRODUCTION: The primary objective of this noncomparative study was to evaluate the pharmacokinetics of ropivacaine during a 48-72-h continuous epidural infusion of ropivacaine in children under 1 year. The secondary objectives were to assess efficacy and safety. METHODS: Neonates and infants (ASA I-III, gestational age > or =37 weeks, > or =2.5 kg, scheduled for major abdominal or thoracic surgery) were included and separated into age groups: 0-30 (neonate), 31-90, 91-180, and 181-365 days. Ethics committee approval and informed parental consent were obtained before inclusion. An epidural catheter was introduced under general anesthesia at the appropriate dermatomal level. An initial bolus dose (0.9-2.0 mg.kg(-1) of ropivacaine 0.2%) was followed by an epidural infusion (0.2 mg.kg(-1).h(-1) for infants <180 days or 0.4 mg.kg(-1).h(-1) for infants >180 days). Plasma samples were collected every 12 h from 24 h, and on termination of the epidural infusion. Postoperative pain was evaluated using both the Objective Pain Scale and a four-graded descriptive scale. RESULTS: Forty-five infants, median age 116 (0-362) days, were included. Forty-three and 19 patients received an infusion for at least 48 and 72 h, respectively. Satisfactory analgesia was provided in the majority, only 20 patients were given supplementary medication during the infusion. In all age groups, plasma concentrations of unbound ropivacaine leveled at 24 h, without any further increase at 48 and 72 h. Because of lower clearance of unbound ropivacaine in neonates (mean 33 ml.min(-1).kg(-1)) than in infants above the age of 30 days (80, 124, and 163 ml.min(-1).kg(-1), respectively, in the age groups 31-90, 91-180, and 180-365 days), unbound ropivacaine concentrations at the end of infusion were higher in neonates [median 0.10 mg.l(-1) (0.04-0.21 mg.l(-1))] than in infants >30 days [median 0.03 mg.l(-1) (0.003-0.10 mg.l(-1))]. CONCLUSION: Epidural infusions (0.2-0.4 mg.kg(-1).h(-1) ropivacaine) provided satisfactory pain relief in neonates and infants under 1 year. As plasma concentrations of unbound ropivacaine were not influenced by the duration of the infusion, ropivacaine can be safely used for postoperative epidural infusion for 48-72 h. Levels of unbound ropivacaine were higher in the neonates than in the infants, but were below threshold concentrations for CNS toxicity in adults (> or =0.35 mg.l(-1)). This should not preclude the use of ropivacaine infusions in neonates but suggests a need for caution during the first weeks of life.

Vitamin E modulation of C-reactive protein in smokers with acute coronary syndromes.

Acute coronary syndromes are characterized by the expression of proinflammatory cytokines such as C-reactive protein (CRP). Sustained upregulation of inflammatory markers is associated with an adverse prognosis. Vitamin E is known to have significant anti-inflammatory properties and has been associated with a reduction in cardiovascular events in some studies of high-risk patients. The mechanism of benefit remains controversial. We conducted a randomized, double-blind placebo controlled trial of vitamin E 400 IU daily for 6 months in 110 patients with acute coronary syndromes. Serum samples were collected at enrollment and at 2, 4, and 6 months. CRP, interleukin-6 and the soluble cell adhesion molecules were measured. Vitamin E levels increased significantly in the treatment group (from 31 micromol/l at baseline to 51 micromol/l, p <.0001) and were unchanged in the placebo group (32 micromol/l at baseline to 34 micromol/l, p = NS). CRP levels fell in both the vitamin E group and the placebo group over the treatment period (from 17.2 +/- 2.9 to 6.1 +/- 0.8 mg/l and from 21.5 +/- 4.9 to 5.9 +/- 0.9 mg/l, p = NS for the difference between active and placebo groups). However, vitamin E treatment was associated with significantly lower 6 month CRP levels in smokers versus smokers on placebo (4.7 +/- 0.71 mg/l vs. 8.26 +/- 1.5 mg/l, p =.02). Vitamin E reduces CRP levels in smokers with acute coronary syndromes for up to 6 months after hospitalization.