Glucose-insulin-potassium reduces the incidence of low cardiac output episodes after aortic valve replacement for aortic stenosis in patients with left ventricular hypertrophy: results from the Hypertrophy, Insulin, Glucose, and Electrolytes (HINGE) trial.

BACKGROUND: Patients undergoing aortic valve replacement for critical aortic stenosis often have significant left ventricular hypertrophy. Left ventricular hypertrophy has been identified as an independent predictor of poor outcome after aortic valve replacement as a result of a combination of maladaptive myocardial changes and inadequate myocardial protection at the time of surgery. Glucose-insulin-potassium (GIK) is a potentially useful adjunct to myocardial protection. This study was designed to evaluate the effects of GIK infusion in patients undergoing aortic valve replacement surgery. METHODS AND RESULTS: Patients undergoing aortic valve replacement for aortic stenosis with evidence of left ventricular hypertrophy were randomly assigned to GIK or placebo. The trial was double-blind and conducted at a single center. The primary outcome was the incidence of low cardiac output syndrome. Left ventricular biopsies were analyzed to assess changes in 5' adenosine monophosphate-activated protein kinase (AMPK), Akt phosphorylation, and protein O-linked ß-N-acetylglucosamination (O-GlcNAcylation). Over a 4-year period, 217 patients were randomized (107 control, 110 GIK). GIK treatment was associated with a significant reduction in the incidence of low cardiac output state (odds ratio, 0.22; 95% confidence interval, 0.10 to 0.47; P=0.0001) and a significant reduction in inotrope use 6 to 12 hours postoperatively (odds ratio, 0.30; 95% confidence interval, 0.15 to 0.60; P=0.0007). These changes were associated with a substantial increase in AMPK and Akt phosphorylation and a significant increase in the O-GlcNAcylation of selected protein bands. CONCLUSIONS: Perioperative treatment with GIK was associated with a significant reduction in the incidence of low cardiac output state and the need for inotropic support. This benefit was associated with increased signaling protein phosphorylation and O-GlcNAcylation. Multicenter studies and late follow-up will determine whether routine use of GIK improves patient prognosis.

Evaluation of ThoraQuik: a new device for the treatment of pneumothorax and pleural effusion.

BACKGROUND: ThoraQuik is a device with a unique design incorporating an aspiration port and one-way valve controlled by a three-way tap, fit for purpose for the treatment of pneumothorax and pleural effusion. Its use, safety and efficacy were evaluated in a prospective observational trial. METHODS: Stage 1: The safety and ability of the device to penetrate the chest wall and the ease of use were evaluated in patients undergoing thoracoscopic procedures by introducing the device at a second port site under vision. Stage 2: The device was evaluated on patients with pneumothorax and pleural effusion. Clinical and radiological improvement were endpoints and operator feedback was evaluated. RESULTS: Phase 1: 10 patients (mean age: 48.5 years (18-76 years) six men) were studied between May 2005 and March 2007. Satisfactory penetration of the chest wall and safe entry in the pleural space was achieved. Phase 2: 20 patients (mean age: 59 years (24-81 years) 13 men) were recruited between May 2007 and May 2008. 10 patients presented with pneumothorax (tension pneumothorax, n=1) and 10 had pleural effusions. One patient withdrew consent and another patient was withdrawn as there was no fluid on trial aspiration. Of the 18 who completed the study, 10/18 had partial and 7/18 patients had complete resolution with no change in one. The qualitative assessments of the ThoraQuik in terms of ease of use and utility were positive. CONCLUSIONS: ThoraQuik achieves satisfactory penetration of the chest wall. It was safe and easy to use to manage pneumothoraces and pleural effusions.

The haemodynamic effects of adjunctive hormone therapy in potential heart donors: a prospective randomized double-blind factorially designed controlled trial.

AIMS: The aim of this study was to assess the haemodynamic effects of tri-iodothyronine (T3) and methylprednisolone in potential heart donors. METHODS AND RESULTS: In a prospective randomized double-blind trial, 80 potential cardiac donors were allocated to receive T3 (0.8 microg kg(-1) bolus; 0.113 microg kg(-1) h(-1) infusion) (n = 20), methylprednisolone (1000 mg bolus) (n = 19), both drugs (n = 20), or placebo (n = 21) following initial haemodynamic assessment. After hormone or placebo administration, cardiac output-guided optimization was initiated, using vasopressin as a pressor and weaning norepinephrine and inotropes. Treatment was administered for 5.9 +/- 1.3 h until retrieval or end-assessment. Cardiac index increased significantly (P < 0.001) but administration of T3 and methylprednisolone alone or in combination did not affect this change or the heart retrieval rate. Thirty-five per cent (14/40) of initially marginal or dysfunctional hearts were suitable for transplant at end-assessment. At end-assessment, 50% of donor hearts fulfilled criteria for transplant suitability. CONCLUSION: Cardiac output-directed donor optimization improves donor circulatory status and has potential to increase the retrieval rate of donor hearts. Tri-iodothyronine and methylprednisolone therapy do not appear to acutely affect cardiovascular function or yield.

How does glucose insulin potassium improve hemodynamic performance? Evidence for altered expression of beta-adrenoreceptor and calcium handling genes.

BACKGROUND: Glucose insulin potassium (GIK) improves hemodynamic performance after coronary artery surgery (CABG). We investigated whether this is associated with changes in gene expression of beta1-adrenergic receptor (ADRB1) or other calcium handling proteins. METHODS AND RESULTS: During a randomized double-blind placebo-controlled trial, 48 patients undergoing on-pump CABG, allocated to receive pre-ischemic placebo (5% dextrose) or GIK (40% dextrose, K+ 100 mmol.L(-1), insulin 70 u.L(-1); 0.75 mL.kg(-1).h(-1)) continued for 6 hours after the removal of the aortic cross-clamp (AXC), underwent left ventricular biopsy for analysis of specific mRNAs immediately before AXC, before release of AXC, and 10 minutes after reperfusion (placebo n=24, GIK n=24). GIK or placebo was infused for a mean of 79+/-21 minutes or 79+/-18 minutes pre-ischemia respectively. Serial hemodynamic measurements were performed. Biopsy samples were snap-frozen and stored at -80 degrees C, mRNA was extracted and TaqMan real-time polymerase chain reaction was performed to investigate expression of ADRB1, sarcoplasmic reticulum Ca-ATPase (SERCA2a), and phospholamban (PLB). GIK significantly increased cardiac index versus placebo (P=0.037). TaqMan reverse-transcriptase polymerase chain reaction showed significantly greater ADRB1 mRNA expression at all time points (4.9-fold, 7.4-fold, and 15.6-fold increase, respectively; P<0.001), significantly greater SERCA2a mRNA expression after reperfusion (13.2-fold; P<0.001), and increased PLB mRNA expression at pre-ischemia and reperfusion (P<0.001 for both time-points) in GIK groups versus placebo. CONCLUSIONS: The beneficial hemodynamic effects of GIK therapy are associated with increased ADRB1 and SERCA2a mRNA expression. Further work is therefore warranted to investigate these mRNA effects at the protein level.

Glucose-insulin-potassium and tri-iodothyronine individually improve hemodynamic performance and are associated with reduced troponin I release after on-pump coronary artery bypass grafting.

BACKGROUND: Both glucose-insulin-potassium (GIK) and tri-iodothyronine (T3) may improve cardiovascular performance after coronary artery surgery (CABG) but their effects have not been directly compared and the effects of combined treatment are unknown. METHODS AND RESULTS: In 2 consecutive randomized double-blind placebo-controlled trials, in patients undergoing first time isolated on-pump CABG between January 2000 and September 2004, 440 patients were recruited and randomized to either placebo (5% dextrose) (n=160), GIK (40% dextrose, K+ 100 mmol.L(-1), insulin 70 u.L(-1)) (0.75 mL.kg(-1) h(-1)) (n=157), T3 (0.8 microg.kg(-1) followed by 0.113 microg.kg(-1) h(-1)) (n=63) or GIK+T3 (n=60). GIK/placebo therapy was administered from start of operation until 6 hours after removal of aortic cross-clamp (AXC) and T3/placebo was administered for a 6-hour period from removal of AXC. Serial hemodynamic measurements were taken up to 12 hours after removal of AXC and troponin I (cTnI) levels were assayed to 72 hours. Cardiac index (CI) was significantly increased in both the GIK and GIK/T3 group in the first 6 hours compared with placebo (P<0.001 for both) and T3 therapy (P=0.009 and 0.029, respectively). T3 therapy increased CI versus placebo between 6 and 12 hours after AXC removal (P=0.01) but combination therapy did not. Release of cTnI was lower in all treatment groups at 6 and 12 hours after removal of AXC. CONCLUSIONS: Treatment with GIK, T3, and GIK/T3 improves hemodynamic performance and results in reduced cTnI release in patients undergoing on-pump CABG surgery. Combination therapy does not provide added hemodynamic effect.

Human epicardial adipose tissue expresses a pathogenic profile of adipocytokines in patients with cardiovascular disease.

INTRODUCTION: Inflammation contributes to cardiovascular disease and is exacerbated with increased adiposity, particularly omental adiposity; however, the role of epicardial fat is poorly understood. METHODS: For these studies the expression of inflammatory markers was assessed in epicardial fat biopsies from coronary artery bypass grafting (CABG) patients using quantitative RT-PCR. Further, the effects of chronic medications, including statins, as well as peri-operative glucose, insulin and potassium infusion, on gene expression were also assessed. Circulating resistin, CRP, adiponectin and leptin levels were determined to assess inflammation. RESULTS: The expression of adiponectin, resistin and other adipocytokine mRNAs were comparable to that in omental fat. Epicardial CD45 expression was significantly higher than control depots (p < 0.01) indicating significant infiltration of macrophages. Statin treated patients showed significantly lower epicardial expression of IL-6 mRNA, in comparison with the control abdominal depots (p < 0.001). The serum profile of CABG patients showed significantly higher levels of both CRP (control: 1.28 +/- 1.57 microg/mL vs CABG: 9.11 +/- 15.7 microg/mL; p < 0.001) and resistin (control: 10.53 +/- 0.81 ng/mL vs CABG: 16.8 +/- 1.69 ng/mL; p < 0.01) and significantly lower levels of adiponectin (control: 29.1 +/- 14.8 microg/mL vs CABG: 11.9 +/- 6.0 microg/mL; p < 0.05) when compared to BMI matched controls. CONCLUSION: Epicardial and omental fat exhibit a broadly comparable pathogenic mRNA profile, this may arise in part from macrophage infiltration into the epicardial fat. This study highlights that chronic inflammation occurs locally as well as systemically potentially contributing further to the pathogenesis of coronary artery disease.

Glucose and insulin influences on heart and brain in cardiac surgery.

The elective global ischemia of on-pump coronary artery bypass surgery contributes to the incidence of postoperative mortality, complications, and use of resources. In addition to cardiopulmonary bypass and techniques for myocardial protection such as aortic cross clamp, ventricular fibrillation, and cardioplegia, the administration of systemic glucose-insulin-potassium (GIK) in the perioperative period may act as both a metabolic modulator and potential inodilator. GIK may therefore serve to protect the myocardium and promote adequate cardiac and hemodynamic performance that would improve patient recovery. Cell, tissue, and animal experiments have determined a number of mechanisms of action by which this may be achieved, with increasing focus on insulin as the key component. The original concepts centered on GIK during or after ischemia switching metabolism away from that based on non-esterified fatty acids toward a more favorable glucose-based metabolism and thus improving the efficiency of adenosine triphosphate production and glycogen preservation. Insulin's ability to reduce intracellular fatty acid metabolism may also reduce cellular membrane damage. More recently other mechanisms have also been suggested, including osmotic, oxygen free radical scavenging, and antiapoptotic and anti-inflammatory effects. However, trials that have examined the role of GIK in cardiac surgery have been small, open label, and involved a wide variety of regimens. They have demonstrated improved glycogen preservation, reduced infarct size, reduced incidences of dysrhythmias, need for inotropic agents, and low cardiac output state, and overall reduced lengths of stay. The perceived need to achieve strict blood glucose control to reduce neurologic injury and improve overall mortality have conflicted with its practical difficulties, particularly during cold cardiopulmonary bypass, and the exact role of supplemental glucose administration and resulting hyperglycemia require re-examination.

Which troponometric best predicts midterm outcome after coronary artery bypass graft surgery?

BACKGROUND: Various troponin I measurements (troponometrics) have been used as surrogate markers of patient outcome after coronary artery bypass grafting (CABG). Our aim was to define the postoperative troponometric best able to predict in-hospital and late mortality. METHODS: In 440 patients (seen from January 2000 to September 2004) undergoing isolated on-pump CABG with standardized anesthesia, perfusion, cardioplegia, and postoperative care, we followed all-cause mortality (census June 2009, 100% complete). Subjects underwent troponin I (cardiac troponin I [cTnI]) estimation at baseline and 6, 12, 24, 48, and 72 hours postoperatively, and individual time-point cTnI (T6, T12, T24, T48, T72), peak cTnI (Cmax), increase in cTnI between 6 and 12 hours (T↑6-12) and 6 and 24 hours (T↑6-24), cumulative area under the curve cTnI (CAUC24, CAUC48, and CAUC72), and cTnI≥13 ng·mL(-1) at any time point were each analyzed using univariate and multivariable Cox models to identify the probability of in-hospital and late death. Logistic EuroSCOREs and calculated creatinine clearance (CrCl) were also included. The Akaike information criterion (AIC) was used to determine goodness of fit. RESULTS: There were 62 of 440 deaths after a median (interquartile range) follow-up period of 7.0 (5.7 to 8.1) years. Univariate Cox analysis demonstrated T12, T24, T48, T72, T↑6-12, T↑6-24, standardized CAUC24, CAUC48, and CAUC72 each to be predictors of midterm mortality. On Cox multivariable analysis in models incorporating both logistic EuroSCOREs and CrCl, both T72 (hazard ratio [HR], 95% confidence interval [CI], 1.10 [1.06 to 1.14]; p<0.001) and CAUC72 (1.45 [1.26 to 1.62], p<0.001) were identified as independent predictors of mortality. Of these, CAUC72 was superior based on the lowest AIC. CONCLUSIONS: In myocardial protection studies, serial troponin I data should be collected until 72 hours postoperatively to calculate CAUC72, as this troponometric best predicts midterm mortality.

Early donor management increases the retrieval rate of lungs for transplantation.

BACKGROUND: Lung transplantation activity is frustrated by donor lung availability. We sought to examine the effect of active donor management and hormone administration on pulmonary function and yield in cadaveric heart-beating potential lung donors. METHODS: We studied 182 potential lung donors (arterial oxygen tension [PaO2]/fractional inspired oxygen [FIO2] ratio > or = 230). From this group, 60 patients (120 lungs) were allocated, within a randomized trial, to receive methylprednisolone (1 g), triiodothyronine (0.8 microg/kg bolus and 0.113 microg/kg/h infusion), both methylprednisolone and triiodothyronine, or placebo as soon as feasible after consent and initial assessment. Trial donors underwent protocol-guided optimization of ventilation and hemodynamics, lung water assessment, and bronchoscopy. Function was assessed by PaO2/FIO2 ratio, extravascular lung water index (EVLWI), and pulmonary vascular resistance (PVR). A nontrial group of 122 donors (244 lungs) received similar management without bronchoscopy, pulmonary artery flotation catheter monitoring, or lung water assessment. RESULTS: Within the trial, management commenced within a median of 2 hours (interquartile range, 0.5 to 3.5 hours) of consent and continued for an average of 6.9 +/- 1.2 hours. The PaO2/FIO2 ratio deteriorated (p = 0.028) from 397 +/- 78 (95% CL, 376 to 417) to 359 +/- 126 (95% CL, 328 to 390) and EVLWI from 9.7 +/- 4.5 mL/kg (95% CL, 8.6 to 10.9 mL/kg) to 10.8 +/- 5.2 mL/kg (95% CL, 9.4 to 12.2 mL/kg; p = 0.009). PVR remained unchanged (p = 0.28). At end management, 48 of 120 trial lungs (40%) were transplanted versus 66 of 244 nontrial lungs (27%; p = 0.016). Neither methylprednisolone and triiodothyronine nor T3 increased lung yield or affected PaO2/FIO2 or EVLWI; however, methylprednisolone attenuated the increase in EVLWI (p = 0.009). CONCLUSIONS: Early active management of lung donors increases yield. Steroid administration reduces progressive lung water accumulation.

The morphologic left ventricle that requires training by means of pulmonary artery banding before the double-switch procedure for congenitally corrected transposition of the great arteries is at risk of late dysfunction.

OBJECTIVE: The aim of this study was to compare the outcome of the double-switch procedure for congenitally corrected transposition of the great arteries for patients completing morphologic left ventricle training by means of pulmonary artery banding with the outcome of patients whose morphologic left ventricle did not require training. METHODS: A retrospective study of all patients undergoing the double-switch procedure from 1991 through 2004 was performed. Patients were divided into 2 groups: those not requiring morphologic left ventricle training (n = 33) and those completing morphologic left ventricle training by means of pulmonary artery banding (n = 11). RESULTS: The time spent with the morphologic left ventricle conditioned at systemic pressures was longer for the group not requiring morphologic left ventricle training (median, 730 days; interquartile range, 399-1234 vs median, 436 days; interquartile range, 411-646; P = .19). The overall mortality (not requiring morphologic left ventricle training, 12.1%; requiring morphologic left ventricle training, 9.1%; P = 1) and rate of death/transplantation, development of moderate-to-severe morphologic left ventricle dysfunction, or both (not requiring morphologic left ventricle training, 21.2%; requiring morphologic left ventricle training, 45.5%; P = .14) were similar between groups. Actuarial freedom from death/transplantation with good morphologic left ventricular function was superior for patients whose morphologic left ventricle did not require training (P = .04). The follow-up was not different between groups (not requiring training: median, 1435 days [interquartile range, 285-2570 days]; requiring morphologic left ventricle training: median, 568 days [interquartile range, 399-1465 days]; P = .14). On multivariate analysis, the completion of morphologic left ventricle training predicted death/transplantation, development of moderate-to-severe morphologic left ventricle dysfunction, or both (P = .02). CONCLUSIONS: The early results of the double-switch procedure in patients whose morphologic left ventricle required training compare favorably with those of patients whose morphologic left ventricle required no training. There is an increased risk of deterioration of morphologic left ventricle function over time in patients whose morphologic left ventricle requires training, and these patients need to be followed up regularly to detect this.

Improved myocardial protection during coronary artery surgery with glucose-insulin-potassium: a randomized controlled trial.

OBJECTIVE: We sought to assess the role of glucose-insulin-potassium in providing myocardial protection in nondiabetic patients undergoing coronary artery surgery with cardiopulmonary bypass. METHODS: A prospective, randomized, double-blind, placebo-controlled trial was conducted at a single-center university hospital performing adult cardiac surgery. Two hundred eighty nondiabetic adult patients undergoing first-time elective or urgent isolated multivessel coronary artery bypass grafting were prospectively randomized to receive glucose-insulin-potassium infusion or placebo (dextrose 5%) before, during, and for 6 hours after surgical intervention. Anesthetic, cardiopulmonary bypass, myocardial protection, and surgical techniques were standardized. The primary end point was postreperfusion cardiac index. Secondary end points were systemic vascular resistance index, the incidence of low cardiac output episodes, inotrope and vasoconstrictor use, and biochemical-electrocardiographic evidence of myocardial injury. The incidence of dysrhythmias and infections requiring treatment was recorded prospectively. RESULTS: The glucose-insulin-potassium group experienced higher cardiac indices (P < .001) throughout infusion and reduced vascular resistance (P < .001). The incidence of low cardiac output episodes was 15.9% (22/138) in the glucose-insulin-potassium group and 27.5% (39/142) in the placebo group (P = .021). Inotropes were required in 18.8% (26/138) of the glucose-insulin-potassium group and 40.8% (58/142) of the placebo group (P < .001). Fewer patients in the glucose-insulin-potassium group (12.3% [16/133]) versus those in the placebo group (23.4% [32/137]) had significant myocardial injury (P = .017). Noncardiac morbidity was not different. CONCLUSION: Glucose-insulin-potassium therapy improves early postoperative cardiovascular performance, reduces inotrope requirement, and might reduce myocardial injury. These potential benefits are not at the expense of increased noncardiac morbidity.