Rolf Svedjeholm

The Society of Thoracic Surgeons Practice Guideline Series: Blood Glucose Management During Adult Cardiac Surgery

The Society of Thoracic Surgeons Practice Guideline Series : Blood Glucose Management During Adult Cardiac Surgery

Early postoperative outcome and medium-term survival in 540 diabetic and 2239 nondiabetic patients undergoing coronary artery bypass grafting

BACKGROUND An increasing proportion of patients undergoing coronary artery bypass grafting (CABG) are diabetics. Patient characteristics, early postoperative outcome, and midterm survival in diabetic patients after CABG were investigated. METHODS A total of 2779 consecutive patients undergoing isolated CABG during 1995 to 1999 were studied, 19.4% of whom had diabetes mellitus. Demographic and peri-procedural data were registered prospectively in a computerized institutional database. RESULTS The diabetic group was younger and included a higher proportion of women, and patients with hypertension, triple-vessel disease, and unstable angina. They required a higher number of bypasses, and longer cross-clamp and cardiopulmonary bypass times. Intensive care unit and hospital stays were prolonged and the need for inotropic agents, hemotransfusions, and dialysis was higher in the diabetic group. Renal failure, stroke (4.3% versus 1.7%), mediastinitis, and wound infections were more frequently encountered. Thirty-day mortality was 2.6% versus 1.6% (p = 0.15). Cumulative 5-year survival was 84.4% versus 91.3% (p < 0.001). CONCLUSIONS Short-term mortality was acceptable in diabetic patients after CABG but they had increased postoperative morbidity in comparison with nondiabetic patients, particularly with regard to renal function, cerebral complications, and infections. Midterm survival was impaired in diabetic patients mainly because of a less favorable outcome in patients treated with insulin.

Glutamate and high-dose glucose-insulin-potassium (GIK) in the treatment of severe cardiac failure after cardiac operations

Postischemic derangement of myocardial metabolism that is further aggravated by the systemic neuroendocrine response to surgical trauma may explain reversible myocardial dysfunction after cardiac surgical procedures. Since 1991, all patients with signs of cardiac failure after operation for ischemic heart disease (45/515 patients) were treated according to our metabolic strategy. Sixteen patients in whom we previously would have considered use of an intraaortic balloon pump were treated by prolonged unloading of the heart with cardiopulmonary bypass, by glutamate infusion, and by high-dose glucose-insulin-potassium. Rapid improvement in hemodynamic performance was seen in the first hour and almost full recovery within 6 hours in the surviving patients (12/16). None of the 3 patients requiring mechanical assist survived. Our early clinical experience suggests that metabolic support with glutamate and high-dose glucose-insulin-potassium is a safe treatment with a high success rate in reversible cardiac failure.

Are electrocardiographic Q-wave criteria reliable for diagnosis of perioperative myocardial infarction after coronary surgery?

OBJECTIVE A major assumption in cardiovascular medicine is that Q-waves on the electrocardiogram indicate major myocardial tissue damage. The appearance of a new Q-wave has therefore been considered the most reliable criterion for diagnosis of perioperative myocardial infarction (PMI) in cardiac surgery. In a study, originally intended to evaluate troponin-T as a marker of PMI, analysis of our data aroused the need to address the reliability of Q-wave criteria for diagnosis of PMI. METHODS In 302 consecutive patients undergoing coronary surgery, Q-wave and other electrocardiogram (ECG) criteria were compared with biochemical markers of myocardial injury and the postoperative course. All ECGs were analysed by a cardiologist blinded to the biochemical analyses and the clinical course. RESULTS The incidence of positive Q-wave criteria was 8.1%. Combined biochemical (CK-MB > or = 70 microg/l) and Q-wave criteria were found in 1.0%. Patients with new Q-waves did not have CK-MB or troponin-T levels significantly different from those without Q-waves. More than 25% of the Q-waves were associated with plasma troponin-T below the reference level (< 0.2 microg/l) on the fourth postoperative day. Q-wave criteria alone did not influence the postoperative course. In contrast, biochemical markers correlated with clinical outcome. CONCLUSIONS The majority of Q-waves appearing after coronary surgery were not associated with major myocardial tissue damage, and according to troponin-T one-fourth of the Q-waves were not associated with myocardial necrosis. Furthermore, the appearance of Q-waves had little influence on short term clinical outcome. Therefore, the use of Q-wave criteria as the gold standard for diagnosis of PMI may have to be questioned.

Coronary artery bypass grafting-related bleeding complications in patients treated with ticagrelor or clopidogrel: a nationwide study

Abstract Aims Excessive bleeding impairs outcome after coronary artery bypass grafting (CABG). Current guidelines recommend withdrawal of clopidogrel and ticagrelor 5 days (120 h) before elective surgery. Shorter discontinuation would reduce the risk of thrombotic events and save hospital resources, but may increase the risk of bleeding. We investigated whether a shorter discontinuation time before surgery increased the incidence of CABG-related major bleeding complications and compared ticagrelor- and clopidogrel-treated patients. Methods and results All acute coronary syndrome patients in Sweden on dual antiplatelet therapy with aspirin and ticagrelor (n = 1266) or clopidogrel (n = 978) who underwent CABG during 2012–13 were included in a retrospective observational study. The incidence of major bleeding complications according to the Bleeding Academic Research Consortium-CABG definition was 38 and 31%, respectively, when ticagrelor/clopidogrel was discontinued <24 h before surgery. Within the ticagrelor group, there was no significant difference between discontinuation 72–120 or >120 h before surgery [odds ratio (OR) 0.93 (95% confidence interval, CI, 0.53–1.64), P = 0.80]. In contrast, clopidogrel-treated patients had a higher incidence when discontinued 72–120 vs. >120 h before surgery (OR 1.71 (95% CI 1.04–2.79), P = 0.033). The overall incidence of major bleeding complications was lower with ticagrelor [12.9 vs. 17.6%, adjusted OR 0.72 (95% CI 0.56–0.92), P = 0.012]. Conclusion The incidence of CABG-related major bleeding was high when ticagrelor/clopidogrel was discontinued <24 h before surgery. Discontinuation 3 days before surgery, as opposed to 5 days, did not increase the incidence of major bleeding complications with ticagrelor, but increased the risk with clopidogrel. The overall risk of major CABG-related bleeding complications was lower with ticagrelor than with clopidogrel.

Predictors of atrial fibrillation in patients undergoing surgery for ischemic heart disease.

OBJECTIVES Atrial fibrillation (AF) remains a common problem after cardiac surgery. AF increases the risk for stroke and is associated with increased length of hospitalization. The aim of this study was to analyze risk factors for postoperative AF in a uniformly managed cohort of patients. DESIGN The records of 775 consecutive patients undergoing coronary artery bypass grafting (CABG) or CABG + valve procedures were examined. Forward stepwise multiple logistic regression analysis was used for statistical evaluation. RESULTS Mean age was 64.6 +/- 8.7 years. The incidence of AF was 29.1% in patients undergoing isolated CABG and 48.6% after CABG + valve procedures. Multivariate analysis identified advanced age (p = 0.000003), low postoperative mixed venous oxygen saturation (p = 0.0018), hypertension (p = 0.0059), preoperative history of AF (p = 0.023) and the need for mechanical circulatory support (p = 0.030) as predictors for postoperative AF. CONCLUSIONS In agreement with previous studies, advanced age was the most important predictor of AF. Hypertension, history of AF and signs of circulatory failure were also predictive of AF. Preventive measures against AF should preferably be tested in high-risk populations, such as elderly patients.

Rationale for metabolic support with amino acids and glucose-insulin-potassium (GIK) in cardiac surgery

Myocardial metabolism and the current state of metabolic intervention under conditions relevant to cardiac surgery are reviewed. The rationale for metabolic support differs considerably in various settings of cardiac surgery. Although preventive measures are theoretically attractive, their use in the preoperative setting remains to be clarified. Amino acid enrichment of blood cardioplegia seems to be justified by an abundance of animal experimental data. In the postoperative setting of cardiac surgery, metabolic abnormalities may explain reversible myocardial dysfunction. Further, the combined effects of ischemia and the systemic neuroendocrine response to surgical trauma may adversely affect recovery. Amino acids, particularly glutamate, seem vital for metabolic recovery in this setting. Treating the relative shortage of glutamate occurring during this period by the administration of exogenous glutamate and counteracting the effects of the systemic neuroendocrine stress response by high-dose glucose-insulin-potassium are measures that have been shown to improve the metabolic state of the heart and subsequently myocardial performance.

Incidence, microbiological findings and clinical presentation of sternal wound infections after cardiac surgery with and without local gentamicin prophylaxis

Sternal wound infection (SWI) is a serious complication after cardiac surgery. In a previous randomized controlled trial, the addition of local collagen-gentamicin in the sternal wound before wound closure was found to significantly reduce the incidence of postoperative wound infections compared with the routine intravenous prophylaxis of isoxazolyl-penicillin only. The aims of the present study were to analyse the microbiological findings of the SWIs from the previous trial as well as to correlate these findings with the clinical presentation of SWI. Differences in clinical presentation of SWIs, depending on the causative agent, could be identified. Most infections had a late, insidious onset, and the majority of these were caused by staphylococci, predominantly coagulase-negative staphylococci. The clinically most fulminant infections were caused by gram-negative bacteria and presented early after surgery. Local administration of gentamicin reduced the incidence of SWIs caused by all major, clinically important bacterial species. Propionibacterium acnes was identified as a possible cause of SWI and may be linked to instability in the sternal fixation. There was no indication of an increase in the occurrence of gentamicin-resistant bacterial isolates in the treatment group. Furthermore, the addition of local collagen-gentamicin reduced the incidence of SWIs caused by methicillin-resistant coagulase-negative staphylococci. This technique warrants further evaluation as an alternative to prophylactic vancomycin in settings with a high prevalence of methicillin-resistant Staphylococcus aureus.

Effects of high-dose glucose–insulin–potassium on myocardial metabolism after coronary surgery in patients with Type II diabetes

The effects of glucose-insulin-potassium (GIK) on cardiac metabolism have been studied previously in non-diabetic patients after cardiac surgery. Although patients with diabetes mellitus can be expected to benefit most from such treatment, the impact of GIK in diabetic patients undergoing cardiac surgery remains unexplored. Therefore the present study investigates the effects of high-dose GIK on myocardial substrate utilization after coronary surgery in patients with Type II diabetes. A total of 20 patients with Type II diabetes undergoing elective coronary surgery were randomly allocated to either post-operative high-dose GIK or standard post-operative care, including insulin infusion if necessary to keep blood glucose below 10 mmol/l. Myocardial substrate utilization was studied using the coronary sinus catheter technique. Haemodynamic state was assessed with the aid of Swan-Ganz catheters. High-dose GIK caused a shift towards carbohydrate utilization, with significant lactate uptake throughout the study period and significant uptake of glucose after 4 h. Arterial levels of non-esterified fatty acids and beta-hydroxybutyric acid decreased, and after 1 h no significant uptake of these substrates was found. Increases in the cardiac index and stroke volume index were found in patients treated with high-dose GIK. A decrease in systemic vascular resistance was found both in the control group and in the high-dose GIK group. We conclude that high-dose GIK can be used in diabetic patients after cardiac surgery to promote carbohydrate uptake at the expense of non-esterified fatty acids and beta-hydroxybutyric acid. This could have implications for treatment of the diabetic heart in association with surgery and ischaemia.

Collagen-gentamicin implant for prevention of sternal wound infection; long-term follow-up of effectiveness

In a previous randomized controlled trial (LOGIP trial) the addition of local collagen-gentamicin reduced the incidence of postoperative sternal wound infections (SWI) compared with intravenous prophylaxis only. Consequently, the technique with local gentamicin was introduced in clinical routine at the two participating centers. The aim of the present study was to re-evaluate the technique regarding the prophylactic effect against SWI and to detect potential shifts in causative microbiological agents over time. All patients in this prospective two-center study received prophylaxis with application of two collagen-gentamicin sponges between the sternal halves in addition to routine intravenous antibiotics. All patients were followed for 60 days postoperatively. From January 2007 to May 2008, 1359 patients were included. The 60-day incidences of any SWI was 3.7% and of deep SWI 1.5% (1.0% mediastinitis). Both superficial and deep SWI were significantly reduced compared with the previous control group (OR=0.34 for deep SWI, P<0.001). There was no increase in the absolute incidence of aminoglycoside resistant agents. The majority of SWI were caused by coagulase-negative staphylococci (CoNS). The incidence of deep SWI caused by Staphylococcus aureus was 0.07%. The results indicate a maintained effect of the prophylaxis over time without absolute increase in aminoglycoside resistance. (ClinicalTrials.gov NCT00484055).