Acute myocardial dysfunction and recovery: a common occurrence after coronary bypass surgery

Myocardial protection using single dose del Nido Cardioplegia with and without topical cooling

INTRODUCTION

Del Nido cardioplegia (DN) is gaining acceptance in adult cardiac surgery but there is paucity of experimental data regarding its efficacy. We set out to assess the safety and efficacy of single-dose DN with and without topical cooling (TC) versus multi-dose blood cardioplegia (BC).

METHODS

Thirty-two healthy adult sheep had pressure-volume (PV) catheters placed in the left (LV) and right (RV) ventricle. Animals were assigned to receive cold (4°C) antegrade solution for a 60-min arrest using: (1) multi-dose (every 20 min) BC with TC (n = 11), (2) single-dose DN with TC (DN-C, n = 10), or (3) single-dose DN without TC (DN-H, n = 11). LV and RV PV-derived indexes, epicardial echocardiographic strains, and blood samples were acquired before CPB and at 1, 2, and 3 h of reperfusion. Dobutamine bolus (2.5 μg) was given after 3 h to test for myocardial reserve.

RESULTS

Time to rhythm restoration was shortest (54 ± 29 s, 118 ± 167 s, and 172 ± 170 s for DN-H, DN-C, and BC, respectively; p = 0.024) and number of shocks lowest (1.7 ± 1.8, 3.6 ± 2.8, and 5.6 ± 4.6 for DN-H, DN-C, and BC, respectively; p = 0.020) in DN-H group. Hemodynamic, load-independent myocardial function, echocardiographic, and metabolic data revealed only slight differences between groups. Troponin I levels did not differ between groups. With dobutamine, preload-recruitable stroke work of both LV (136 ± 50%, 131 ± 31%, 142 ± 58% for BC, DN-C and DN-H, respectively; p = 0.993) and RV (161 ± 67%, 185 ± 45%, 166 ± 75% for BC, DN-C and DN-H respectively; p = 0.580) increased similarly.

CONCLUSIONS

Single-dose DN cardioplegia with or without topical cooling offered comparable biventricular myocardial protection to multi-dose BC for a 60-min arrest in sheep.

Del Nido versus cold blood cardioplegia in adult patients with impaired ejection fraction undergoing valvular and complex heart surgery

BACKGROUND

There is sparse evidence on the efficacy of del Nido cardioplegia in high-risk patients with reduced ejection fraction undergoing valvular or complex heart surgery, and further investigation is required.

METHODS

An institutional registry was searched for patients who underwent valvular or complex heart surgery and had an ejection fraction <40%. Subjects who received del Nido cardioplegia (DNC) and cold blood cardioplegia (CBC) were selected. Propensity matching was performed with age, gender, and number of conducted procedures as matching criteria. A comparative analysis was performed on primary endpoints of the troponin rise and changes in ejection fraction (EF). A composite endpoint of a troponin rise of ≥20× baseline or fall of EF≥5% was assessed in a multivariate analysis. Other perioperative complications are reported.

RESULTS

One hundred patients from the DNC group were matched to the 100 patients in the CBC group. There were no differences between groups at baseline. Postoperatively, lower troponin values were observed in the DNC group at 12 hours (median; IQR: 523.2;349.1-740.4 pg/mL vs. 787.6;443.6-1689.0 pg/mL; P=0.016) and 36 hours (median; IQR: 426.1;337.2-492.1 pg/mL vs. 653.7;398.8-1737.5 pg/mL; P=0.044). Fewer patients in the DNC group had a fall in EF≥5% (7% vs. 16%; P=0.046). The multivariable analysis did not reveal a significant predictor of composite endpoint.

CONCLUSIONS

In patients with impaired contractility undergoing valvular and complex procedures, the use of del Nido cardioplegia as an alternative to cold blood cardioplegia is associated with lower troponin release and improved preservation of ejection fraction.

ATP-Sensitive Potassium Channel Opener Diazoxide Reduces Myocardial Stunning in a Porcine Regional With Subsequent Global Ischemia Model

Background ATP-sensitive potassium channels are inhibited by ATP and open during metabolic stress, providing endogenous myocardial protection. Pharmacologic opening of ATP potassium channels with diazoxide preserves myocardial function following prolonged global ischemia, making it an ideal candidate for use during cardiac surgery. We hypothesized that diazoxide would reduce myocardial stunning after regional ischemia with subsequent prolonged global ischemia, similar to the clinical situation of myocardial ischemia at the time of revascularization. Methods and Results Swine underwent left anterior descending occlusion (30 minutes), followed by 120 minutes global ischemia protected with hyperkalemic cardioplegia±diazoxide (N=6 each), every 20 minutes cardioplegia, then 60 minutes reperfusion. Cardiac output, time to wean from cardiopulmonary bypass, left ventricular (LV) function, caspase-3, and infarct size were compared. Six animals in the diazoxide group separated from bypass by 30 minutes, whereas only 4 animals in the cardioplegia group separated. Diazoxide was associated with shorter but not significant time to wean from bypass (17.5 versus 27.0 minutes; P=0.13), higher, but not significant, cardiac output during reperfusion (2.9 versus 1.5 L/min at 30 minutes; P=0.05), and significantly higher left ventricular ejection fraction at 30 minutes (42.5 versus 15.8%; P<0.01). Linear mixed regression modeling demonstrated greater left ventricular developed pressure (P<0.01) and maximum change in ventricular pressure during isovolumetric contraction (P<0.01) in the diazoxide group at 30 minutes of reperfusion. Conclusions Diazoxide reduces myocardial stunning and facilitates separation from cardiopulmonary bypass in a model that mimics the clinical setting of ongoing myocardial ischemia before revascularization. Diazoxide has the potential to reduce myocardial stunning in the clinical setting.

Comparison of effects of sevoflurane versus propofol on left ventricular longitudinal global and regional strain in patients undergoing on-pump coronary artery bypass grafting

Background:

Assessment of myocardial deformation by quantifying peak systolic longitudinal strain (PSLS) is a sensitive and robust index to detect subclinical myocardial dysfunction. We hypothesize that sevoflurane by virtue of anesthetic preconditioning preserves myocardial function better than propofol.

Aims:

The authors have assessed the effects of sevoflurane and propofol on global longitudinal strain (GLS) as a primary outcome in patients undergoing on-pump coronary artery bypass grafting. Our secondary aim was to assess the pattern of regional distribution of segmental PSLS between the groups.

Materials and Methods:

Fifty patients with normal left ventricular function undergoing coronary artery bypass grafting were analyzed in this prospective observational study. Consecutive patients received either propofol (P) or sevoflurane (S) anesthesia.

Measurements:

Trans-esophageal echocardiographic images (mid-esophageal four-chamber, two-chamber, and three-chamber (long-axis)) were recorded during the precardiopulmonary bypass (CPB) and post-CPB period. Strain analysis (GLS/segmental PSLS) was done offline by investigators blinded to the study. The inotropic score, duration of inotropic support, and mechanical ventilation required were recorded.

Results:

Following cardiopulmonary bypass and coronary revascularization, GLS reduced significantly in both the groups (P < 0.05). In the S-group, significant reduction in segmental strain was observed only in apical segments including apex, whereas in P-group significant reduction in segmental strain was seen in mid- and apical segments. The postoperative VIS, duration of inotropes/vasopressor required, and mechanical ventilation were similar in both the groups.

Conclusions:

There are no significant differences in global left ventricular function as assessed by GLS between patients anesthetized with sevoflurane or propofol. However, regional PSLS was better preserved in the S-group compared to P-group.

Utility of NT-proBNP as an objective marker of postoperative heart failure after coronary artery bypass surgery: a prospective observational study

Background

Postoperative heart failure (PHF) is the main cause for mortality after cardiac surgery but unbiased evaluation of PHF is difficult. We investigated the utility of postoperative NT-proBNP as an objective marker of PHF after coronary artery bypass surgery (CABG).

Methods

Prospective study on 382 patients undergoing isolated CABG for acute coronary syndrome. NT-proBNP was measured preoperatively, the first (POD1) and third postoperative morning (POD3). A blinded Endpoints Committee used prespecified criteria for PHF. Use of circulatory support was scrutinized.

Results

After adjusting for confounders PHF was associated with 1.46 times higher NT-proBNP on POD1 (p = 0.002), 1.54 times higher on POD3 (p < 0.0001). In severe PHF, NT-proBNP was 2.18 times higher on POD1 (p = 0.001) and 1.81 times higher on POD3 (p = 0.019). Postoperative change of NT-proBNP was independently associated with PHF (OR 5.12, 95% CI 1.86–14.10, p = 0.002). The use of inotropes and ICU resources increased with incremental quartiles of postoperative NT-proBNP.

Conclusions

Postoperative NT-proBNP can serve as an objective marker of the severity of postoperative myocardial dysfunction. Due to overlap in individuals, NT-proBNP is useful mainly for comparisons at cohort level. As such, it provides a tool for study purposes when an unbiased assessment of prevention or treatment of PHF is desirable.

Trial registration

ClinicalTrials.gov Identifier: NCT00489827https://clinicaltrials.gov/ct2/show/NCT00489827?term=glutamics&draw=2&rank=1.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13741-021-00194-4.

Time Course of Ventricular Remodeling after Atrial Septal Defect Closure in Adult Patients

Background

Atrial septal defect (ASD) is the most common congenital heart disease. However, the details of cardiac chamber remodeling after surgery are not well known, although this is an important issue that should be analyzed to understand long-term outcomes.

Methods

Between November 2017 and January 2019, cardiac magnetic resonance imaging was performed preoperatively, at a 1-month postoperative follow-up, and at a 1-year postoperative follow-up. Cardiac chamber volume, valve regurgitation volume, and ejection fraction were measured as functions of time.

Results

Thirteen patients (10 men and 3 women) were included. The median age at surgery was 51.4 years. The preoperative median ratio of flow in the pulmonary and systemic circulation was 2.3. The preoperative mean right ventricular (RV) end-diastolic volume index (EDVi) and RV end-systolic volume index (ESVi) had significantly decreased at the 1-month postoperative follow-up (p<0.001, p=0.001, respectively). The decrease in the RVEDVi (p=0.085) and RVESVi (p=0.023) continued until the postoperative 1-year follow-up, although the rate of decrease was slower. Tricuspid valve regurgitation had also decreased at the 1-month postoperative follow-up (p=0.022), and continued to decrease at a reduced rate (p=0.129). Although the RVEDVi and RVESVi improved after ASD closure, the RV volume parameters were still larger than the left ventricular (LV) volume parameters at the 1-year follow-up (RVEDVi vs. LVEDVi p=0.016; RVESVi vs. LVESVi p=0.001).

Conclusion

Cardiac remodeling after ASD closure is common and mainly occurs in the early postoperative period. However, complete normalization does not occur.

Risk factors, resource use, and cost of postoperative low cardiac output syndrome

OBJECTIVE

Low cardiac output syndrome complicates recovery after cardiac surgery. We examined the incidence and risk factors for low cardiac output syndrome and its association with postoperative mortality, morbidity, resource use, and cost.

METHODS

This cross-sectional retrospective observational study examined patients having cardiac surgery captured in the Premier Healthcare Database. Low cardiac output syndrome was defined as the requirement for postoperative mechanical circulatory support and/or hemodynamic instability requiring prolonged inotropic support. Incidence, risk factors, and association of low cardiac output syndrome with postoperative outcomes, including mortality, hospital and intensive care unit length of stay, hospital readmission, and cost at 30 days, 90 days, and 6 months, were examined.

RESULTS

Among 59,810 patients from 164 hospitals having cardiac surgery between July 1, 2012, and June 30, 2014, low cardiac output syndrome developed in 6067 (10.1%) patients. Patients presenting in cardiogenic shock or systolic (± diastolic) heart failure were at greatest risk. Risk-adjusted in-hospital mortality was 12-fold greater with low cardiac output syndrome (odds ratio, 12.0; 95% confidence interval, 10.6-13.5). Risk-adjusted hospital costs (2019$; median [Q1, Q3]) were $64,041 [21,439] in patients who developed low cardiac output syndrome versus $48,086 [16,098] without; P < .001. Increased costs were driven by longer risk-adjusted hospital stay (10.1 [4.5] vs 8.5 [3.8] days); P < .001, intensive care unit (5.5 [2.5] vs 3.3 [1.5] days; P < .001) stay, and all-cause 30-day adjusted hospital readmission rates (mean [SD] 16.6 [8.2]% vs 13.9 [7.2]%; P < .001).

CONCLUSIONS

Cardiac surgical patients who develop postoperative low cardiac output syndrome suffer greater mortality and have greater resource use, health care costs, and all-cause readmission, which informs perioperative decision making, and impacts hospital performance metrics and federal priority to reduce health care costs.

Differential myocardial strain in the early postoperative period in patients receiving arterial vs venous bypass grafts: A hypothesis-generating study

OBJECTIVE

Revascularization via coronary artery bypass grafting (CABG) remains a common therapy for coronary artery disease. CABG-based revascularization is most commonly performed via either single arterial graft (SAG) or multiple arterial grafting (MAG) strategies. Echo-derived global and regional longitudinal strain was used to test where SAG or MAG results in immediate differences in left ventricular (LV) function after CABG.

MATERIALS AND METHODS

Pre- and postprocedural intraoperative transesophageal echos were prospectively collected. Two-dimensional LV images were analyzed for global and regional longitudinal strain (GLS), LV ejection fraction, end-diastolic volume, end-systolic volume, and stroke volume (SV).

RESULTS

Twenty patients underwent open, on-pump CABG (63.9 ± 10 years old, 85% male; 10 with SAG and 10 with MAG. Preprocedural GLS significantly differed between patients with SAG and MAG, with patients with MAG having greater GLS (mean [standard deviation, SD], 20.41 [5.54]) than patients with SAG (16.28 [3.48]). After CABG, in patients with MAG, LV strain decreased both globally (-1.13 [3.15]) and regionally in the anterior-lateral (-1.22 [3.84]) and inferior-lateral regions (-1.32 [5.69]), along with LVEF. In patients with SAG, LV strain increased after CABG globally (1.34 [2.73]) and regionally in the anterior-lateral (1.20 [6.49]) and inferior-lateral regions (0.39 [7.26]), as did LVEF and SV. Postprocedure, more patients with MAG were given vasopressor (100% vs 60%) and inotrope infusions (70% vs 40%) than patients with SAG.

CONCLUSIONS

After CABG, LV function quantified through GLS changes both globally and regionally increased after SAG and decreased after MAG. This finding may have important clinical implications in terms of optimizing intraoperative management for patients with CABG and have the potential to guide the improvement of clinical outcomes.

Tolvaptan can limit postoperative paroxysmal atrial fibrillation occurrence after open-heart surgery

PURPOSE

Tolvaptan administration in the early postoperative period after cardiac surgery rapidly treats fluid retention without affecting the renal function. Tolvaptan also has the benefit of not stimulating the renin-angiotensin and sympathetic nervous systems, which are risk factors for postoperative paroxysmal atrial fibrillation. In this study, we examined the hypothesis that tolvaptan administration reduces postoperative paroxysmal atrial fibrillation and worsening of the renal function incidence in patients who have undergone open-heart surgery.

METHODS

From our previous randomized study, we selected 166 open-heart surgery patients, divided them into 2 groups [tolvaptan group, 83 patients; control (non-tolvaptan) group, 83 patients], and compared the incidence of postoperative paroxysmal atrial fibrillation and worsening of the renal function in the postoperative period between the groups.

RESULTS

The incidence of worsening of the renal function was significantly lower in the tolvaptan group than in the control group (4.8% vs. 15.7%; P = 0.04). The incidence of postoperative paroxysmal atrial fibrillation within 14 days was also significantly lower in the tolvaptan group than in the control group (26.5% vs. 42.2%; P = 0.011).

CONCLUSION

Tolvaptan administration in the early postoperative period after open-heart surgery may reduce the incidence of postoperative paroxysmal atrial fibrillation and worsening of the renal function.

Single center experience with patients on veno arterial ECMO due to postcardiotomy right ventricular failure

OBJECTIVES

Right ventricular (RV) failure is associated with poor outcome and increased mortality in cardiac surgery. Aim of our study was to analyze the outcome of veno arterial extracorporeal membrane oxygenation (va ECMO) therapy in patients with isolated RV failure in postcardiotomy cardiogenic shock (PCS) and to evaluate risk factors associated with 30-day-mortality.

METHODS

Between August 2006 until August 2016, 64 consecutive patients with va ECMO therapy due to fulminant RV failure in PCS were identified and included in this retrospective observation. Further, outcome data and a comparison of va ECMO survivors and nonsurvivors was conducted.

RESULTS

The mean age of the patient cohort was 63 ± 14 years. Patients were treated with va ECMO for 79 ± 61 hours. Twenty-eight patients (44%) were successfully weaned off ECMO support. Overall 30-day-mortality was 88% (56/64). Hemoglobin concentration before ECMO implantation, maximum rise of muscle-brain type creatine kinase during ECMO therapy, as well as lactic acid concentration 24 hours after initiation of va ECMO therapy were predictive for 30-day mortality.

CONCLUSION

ECMO therapy in RV failure due to PCS is shown to be associated with an excessive mortality. Regarding our data, va ECMO might only be an appropriate short-term mechanical assist device separating patients form cardiopulmonary bypass with an acceptable weaning rate. Particularly, in case of failed hemodynamic recovery of the right heart on va ECMO, direct RV bypass systems might function as a bailout option. Additionally, cardiac enzymes and lactic acid might provide valuable information in meeting therapy-related decisions.

Effect of Levosimendan Compared to Conventional Inotropic Agents on Hemodynamics and Outcome in Patient with Poor LV Function Undergoing Cardiac Surgery

BACKGROUND

Patients undergoing heart surgery involving cardiopulmonary bypass (CPB) experience global myocardial ischemia with subsequent reperfusion which, despite cardioplegic protection, may result in different degrees of transient ventricular dysfunction. Levosimendan is a "calcium sensitisers", it improves myocardial contractility by sensitising troponin C to calcium without increasing myocardial oxygen consumption and without impairing relaxation and diastolic function.

AIM

To evaluate the adding effect of a calcium sensitiser (levosimendan) compared to the conventional inotropic and vasoactive agent used in the patient with poor left ventricular function undergoing cardiac surgery on different measured hemodynamic variables and the effect on the outcome.

METHODS

It is prospective observational studies were patients were divided into 2 groups of 30 patients each. The first Group received conventional inotropic and vasoactive treatment at different doses, while the other group received levosimendan additionally at a loading dose of 6-12mic/kg according to mean arterial pressure over 0.5 hr followed by 24 hrs infusion at 0.05 to 0.2 mic/kg/min. Hemodynamic data were collected at the end and 30 minutes after CPB, after that at 6, 12, 24, and 36 hours post CPB. Mean arterial pressure (MAP), central venous pressure (CVP), heart rate (HR), mixed venous saturation (Svo2), and base deficit (BD) were measured.

RESULTS

Levosimendan had significantly improved postoperative hemodynamic values as in the mixed venous pressure at different times postoperative (p < 0.05), also the base deficit at different times postoperative (p < 0.05), while there was a significant reduction in systemic vascular resistance as decreased mean arterial pressure in levosimendan group compared to conventional group at 6hrs postoperative mean 77.50 ± 10.81 vs 83.73 ± 10.81 with (p = 0.029), and at 12 hrs postoperative mean 77.37 ± 10.10vs 84.23 ± 13.81 with (p = 0.032), and there was no significant difference in heart rate at different times postoperative between both groups (p > 0.05), while there was no significant effect on mortality between both groups (p = 0.781).

CONCLUSION

Levosimendan had improved hemodynamic parameters significantly with no effect on mortality compared to conventional inotropic agents in a patient with poor left ventricular function undergoing cardiac surgery.

The del Nido versus cold blood cardioplegia in aortic valve replacement: A randomized trial

OBJECTIVES

To compare the cardioprotective efficacy of a solution that requires only a single infusion at the start of the ischemic duration versus a solution that requires multiple infusions.

METHODS

Aortic valve replacement was performed for 150 patients, who were randomized into the del Nido (DN) cardioplegia group or the cold blood (CB) cardioplegia group. The DN cardioplegia was delivered every 90 minutes and the CB cardioplegia was delivered every 20 to 30 minutes, or whenever cardiac activity was observed. The primary endpoints were electrical cardiac activity during crossclamp, ventricular fibrillation during reperfusion, and postoperative troponin and creatine kinase (CK-MB isoenzyme) at 24 and 48 hours.

RESULTS

Electrical activity during crossclamp occurred in 29 (39.7%) patients in the DN group versus 34 (45.3%) patients in the CB group (adjusted P = 1.0). The number of procedures with ventricular fibrillation after removing the crossclamp was 41 (54.7%) in the CB group versus 17 (22.7%) in the DN group (adjusted P = .001; relative risk, 2.41). Troponin values appeared to be lower in the DN group (median, 223.10; interquartile range, 168.35-364.77 pg/mL vs 285.5; 196.20-419.45 pg/mL at 24 hours and 159.60; 125.42-217.20 pg/mL vs 201.60; 160.62-268.45 pg/mL at 48 hours) and CK-MB (median, 14.94; interquartile range, 12.16-20.39 ng/mL vs 17.43; 13.66-22.43 ng/mL at 24 hours and 6.19; 4.41-7.63 ng/mL vs 7.38; 4.74-10.20 ng/mL at 48 hours), but no significance was found.

CONCLUSIONS

The del Nido cardioplegia protocol is an acceptable alternative for cold blood cardioplegia in patients undergoing aortic valve replacement.

Myocardial Protection by Glucose-Insulin-Potassium in Moderate- to High-Risk Patients Undergoing Elective On-Pump Cardiac Surgery: A Randomized Controlled Trial

BACKGROUND

Low cardiac output syndrome is a main cause of death after cardiac surgery. We sought to assess the impact of glucose-insulin-potassium (GIK) to enhance myocardial protection in moderate- to high-risk patients undergoing on-pump heart surgery.

METHODS

A randomized controlled trial was performed in adult patients (Bernstein-Parsonnet score >7) scheduled for elective aortic valve replacement and/or coronary artery bypass surgery. Patients were randomized to GIK (20 IU of insulin, 10 mEq of potassium chloride in 50 mL of glucose 40%) or saline infusion given over 60 minutes on anesthetic induction. The primary end point was postcardiotomy ventricular dysfunction (PCVD), defined as new/worsening left ventricular dysfunction requiring inotropic support (≥120 minutes). Secondary end points were the intraoperative changes in left ventricular function as assessed by transoesophageal echocardiography, postoperative troponin levels, cardiovascular and respiratory complications, and intensive care unit and hospital length of stay.

RESULTS

From 224 randomized patients, 222 were analyzed (112 and 110 in the placebo and GIK groups, respectively). GIK pretreatment was associated with a reduced occurrence of PCVD (risk ratio [RR], 0.41; 95% confidence interval [CI], 0.25-0.66). In GIK-treated patients, the left systolic ventricular function was better preserved after weaning from bypass, plasma troponin levels were lower on the first postoperative day (2.9 ng·mL(-) [interquartile range {IQR}, 1.5-6.6] vs 4.3 ng·mL(-) [IQR, 2.4-8.2]), and cardiovascular (RR, 0.69; 95% CI, 0.50-0.89) and respiratory complications (RR, 0.5; 95% CI, 0.38-0.74) were reduced, along with a shorter length of stay in intensive care unit (3 days [IQR, 2-4] vs 3.5 days [IQR, 2-7]) and in hospital (14 days [IQR, 11-18.5] vs 16 days [IQR, 12.5-23.5]), compared with placebo-treated patients.

CONCLUSIONS

GIK pretreatment was shown to attenuate PCVD and to improve clinical outcome in moderate- to high-risk patients undergoing on-pump cardiac surgery.

Emergency surgery for left main disease: with and without cardioplegic arrest

BACKGROUND

The aims of this study were to evaluate the on-pump beating-heart technique of coronary artery bypass in patients with acute myocardial infarction and left main disease, and to retrospectively compare the early postoperative results with those of conventional on-pump arrested-heart coronary surgery.

METHODS

Eighty-five patients with acute myocardial infarction caused by left main disease, who underwent emergency surgery between January 1998 and April 2017 at Saiseikai Utsunomiya Hospital, were enrolled in this study. Of these patients, 56 were evaluated using propensity-matched analysis. The patients were divided into two groups according to the surgical procedure: group A ( n = 28) had on-pump surgery on the arrested heart, and group B ( n = 28) had on-pump surgery on the beating heart. Early postoperative results were compared between the two groups.

RESULTS

Preoperative and intraoperative characteristics showed no significant differences between the two groups. The peak creatine kinase myocardial band level was significantly lower in group B (group A 151 vs. group B 91 IU·L^-1, p = 0.01). The early mortality rate was higher in group A than group B, but the difference was not significant (group A 28.6% vs. group B 17.9%, p = 0.53).

CONCLUSIONS

There was no significant advantage based on surgical procedure between on-pump beating-heart surgery and on-pump surgery on the arrested heart. On-pump beating-heart coronary artery bypass grafting significantly reduced the peak creatine kinase myocardial band level, but there were no significant differences in the early postoperative data, including the mortality rate and left ventricular function.

Left ventricular-arterial coupling is associated with prolonged mechanical ventilation in severe post-cardiac surgery patients: an observational study

Background

Weaning post-cardiac surgery patients from mechanical ventilation (MV) poses a big challenge to these patients. Optimized left ventricular-arterial coupling (VAC) may be crucial for reducing the MV duration of these patients. However, there is no research exploring the relationship between VAC and the duration of MV. We performed this study to investigate the relationship between left ventricular-arterial coupling (VAC) and prolonged mechanical ventilation (MV) in severe post-cardiac surgery patients.

Methods

This was a single-center retrospective study of 56 severe post-cardiac surgery patients from January 2015 to December 2017 at the Department of Critical Care Medicine of Peking Union Medical College Hospital. Patients were divided into two groups according to the duration of MV (PMV group: prolonged mechanical ventilation group, MV > 6 days; Non-PMV group: non-prolonged mechanical ventilation group, MV ≤ 6 days). Hemodynamics and tissue perfusion data were collected or calculated at admission (T0) and 48 h after admission (T1) to the ICU.

Results

In terms of hemodynamic and tissue perfusion data, there were no differences between the two groups at admission (T0). Compared with the non-prolonged MV group after 48 h in the ICU (T1), the prolonged MV group had significantly higher values for heart rate (108 ± 13 vs 97 ± 12, P = 0.018), lactate (2.42 ± 1.24 vs.1.46 ± 0.58, P < 0.001), and Ea/Ees (5.93 ± 1.81 vs. 4.05 ± 1.20, P < 0.001). Increased Ea/Ees (odds ratio, 7.305; 95% CI, 1.181–45.168; P = 0.032) and lactate at T1 (odds ratio, 17.796; 95% CI, 1.377–229.988; P = 0.027) were independently associated with prolonged MV. There was a significant relationship between Ea/Ees_T1 and the duration of MV (r = 0.512, P < 0.01). The area under the receiver operating characteristic (AUC) of the left VAC for predicting prolonged MV was 0.801, and the cutoff value for Ea/Ees was 5.12, with 65.0% sensitivity and 90.0% specificity.

Conclusions

Left ventricular-arterial coupling was associated with prolonged mechanical ventilation in severe post-cardiac surgery patients. The assessment and optimization of left VAC might be helpful in reducing duration of MV in these patients.

Prophylactic preoperative levosimendan for off-pump coronary artery bypass grafting in patients with left ventricular dysfunction: Single-centered randomized prospective study

Background:

Off-pump coronary artery bypass surgery (OPCAB) is often complicated by hemodynamic instability, especially in patients with prior left ventricular (LV) dysfunction and appropriate choice of inotrope plays a vital role in perioperative management of these patients.

Aim and Objective:

To study hemodynamic effects and immediate outcome of prophylactic infusion of levosimendan in patients with the LV dysfunction undergoing OPCAB surgery and whether this strategy helps in successful conduct of OPCAB surgery.

Materials and Methods:

After Institutional Ethics Committee approval, 60 patients posted for elective OPCAB surgery were randomly divided into two groups (n = 30 each). Patients with the LV ejection fraction <30% were included. Study group was started on injection levosimendan (@ 0.1 μg/kg/min) in the previous night before surgery and continued for 24 h including intraoperative period. Hemodynamic monitoring included heart rate, invasive blood pressure, cardiac index (CI), pulmonary capillary wedge pressure (PCWP), pulse oximetry, and arterial blood gases with serum lactates at as T0 (baseline), T1 (15 min after obtuse marginal and/or PDA anastomoses), T2 (at end of surgery), T3 (6 h after surgery in Intensive Care Unit [ICU]), T4 (12 h after surgery), and T5 (24 h after surgery in ICU). Vasopressor was added to maintain mean arterial pressure >60 mmHg. Chi-square/Fisher's exact/Mid P exact test and Student's t-tests were applied for categorical and continuous data.

Results:

CI was greater and PCWP reduced significantly in Group L during intraoperative and early postoperative period. Serum lactate concentration was lower in patients pretreated with levosimendan. Incidence of postoperative atrial fibrillation (POAF) (36.6 vs. 6.6%; P = 0.01), low cardiac output syndrome (LCOS) (30% vs. 6%; P = 0.02), and acute kidney injury (23.3% vs. 6.7%; P = 0.04) was less in Group L. Three patients (10%) in control group required conversion to cardiopulmonary bypass (CPB) as compared to none in the study group. There was no difference regarding ICU or hospital stay and mortality in both groups.

Conclusion:

Preoperative levosimendan helps in successful conduct of OPCAB and reduces the incidence of LCOS, POAF, conversion to CPB, and requirement of intra-aortic balloon pump.

The spectrum of myocardial homeostasis mechanisms in the settings of cardiac surgery procedures (Review)

Classic cardiac surgery, determined through the function of cardiopulmonary bypass machine and myocardial cardioplegic arrest, represents the most controlled scenario for cardiomyocyte homeostatic disturbances due to systemic inflammatory response and myocardial reperfusion injury. An increasing number of studies have demonstrated that myocardial cell homeostasis in cardiac surgery procedures is a sequence of molecularly interrelated and overlapping mechanisms in the form of apoptosis, autophagy and necrosis, which are activated by a plethora of induced inflammatory mediators and gene-related signaling pathways. In this study, we outline the molecular mechanisms of the cardiomyocyte adaptive homeostatic process and the associated clinical implications, in the settings of classic cardiac surgery procedures.

Current interpretation of myocardial stunning

Myocardial stunning is a temporary post-ischemic cardiac mechanical dysfunction. As such, it is a heterogeneous entity and different conditions can promote its occurrence. Transient coronary occlusion, increased production of catecholamines and endothelin, and myocardial inflammation are all possible causes of myocardial stunning. Possible underlying mechanisms include an oxyradical hypothesis, calcium overload, decreased responsiveness of myofilaments to calcium, and excitation-contraction uncoupling due to sarcoplasmic reticulum dysfunction. The aim of this review is to summarize the clinical conditions that may be responsible for stunned myocardium.

Pyruvate enhancement of cardiac performance: Cellular mechanisms and clinical application

Cardiac contractile function is adenosine-5'-triphosphate (ATP)-intensive, and the myocardium's high demand for oxygen and energy substrates leaves it acutely vulnerable to interruptions in its blood supply. The myriad cardioprotective properties of the natural intermediary metabolite pyruvate make it a potentially powerful intervention against the complex injury cascade ignited by myocardial ischemia-reperfusion. A readily oxidized metabolic substrate, pyruvate augments myocardial free energy of ATP hydrolysis to a greater extent than the physiological fuels glucose, lactate and fatty acids, particularly when it is provided at supra-physiological plasma concentrations. Pyruvate also exerts antioxidant effects by detoxifying reactive oxygen and nitrogen intermediates, and by increasing nicotinamide adenine dinucleotide phosphate reduced form (NADPH) production to maintain glutathione redox state. These enhancements of free energy and antioxidant defenses combine to augment sarcoplasmic reticular Ca²⁺ release and re-uptake central to cardiac mechanical performance and to restore β-adrenergic signaling of ischemically stunned myocardium. By minimizing Ca²⁺ mismanagement and oxidative stress, pyruvate suppresses inflammation in post-ischemic myocardium. Thus, pyruvate administration stabilized cardiac performance, augmented free energy of ATP hydrolysis and glutathione redox systems, and/or quelled inflammation in a porcine model of cardiopulmonary bypass, a canine model of cardiac arrest-resuscitation, and a caprine model of hypovolemia and hindlimb ischemia-reperfusion. Pyruvate's myriad benefits in preclinical models provide the mechanistic framework for its clinical application as metabolic support for myocardium at risk. Phase one trials have demonstrated pyruvate's safety and efficacy for intravenous resuscitation for septic shock, intracoronary infusion for heart failure and as a component of cardioplegia for cardiopulmonary bypass. The favorable outcomes of these trials, which argue for expanded, phase three investigations of pyruvate therapy, mirror findings in isolated, perfused hearts, underscoring the pivotal role of preclinical research in identifying clinical interventions for cardiovascular diseases. Impact statement This article reviews pyruvate's cardioprotective properties as an energy-yielding metabolic fuel, antioxidant and anti-inflammatory agent in mammalian myocardium. Preclinical research has shown these properties make pyruvate a powerful intervention to curb the complex injury cascade ignited by ischemia and reperfusion. In ischemically stunned isolated hearts and in large mammal models of cardiopulmonary bypass, cardiac arrest-resuscitation and hypovolemia, intracoronary pyruvate supports recovery of myocardial contractile function, intracellular Ca²⁺ homeostasis and free energy of ATP hydrolysis, and its antioxidant actions restore β-adrenergic signaling and suppress inflammation. The first clinical trials of pyruvate for cardiopulmonary bypass, fluid resuscitation and intracoronary intervention for congestive heart failure have been reported. Receiver operating characteristic analyses show remarkable concordance between pyruvate's beneficial functional and metabolic effects in isolated, perfused hearts and in patients recovering from cardiopulmonary bypass in which they received pyruvate- vs. L-lactate-fortified cardioplegia. This research exemplifies the translation of mechanism-oriented preclinical studies to clinical application and outcomes.

Comparison of Levosimendan versus Dobutamine in Patients with Moderate to Severe Left Ventricular Dysfunction Undergoing Off-pump Coronary Artery Bypass Grafting: A Randomized Prospective Study

Context:

Recent upsurge in referral of patients with compromised left ventricular (LV) function for cardiac surgery has led to an increasing use inotropes to achieve improvement of tissue perfusion in the perioperative period.

Aims and Objectives:

To compare the hemodynamic effects and immediate postoperative outcomes with levosimendan and dobutamine in patients with moderate to severe LV dysfunction undergoing off-pump coronary artery bypass grafting (OPCAB).

Settings and Design:

University teaching hospital, randomized control study.

Materials and Methods:

Eighty patients were randomly divided into two groups of 40 each. Group I received levosimendan at 0.1 μg/kg/min and Group II received dobutamine at 5 μg/kg/min. Hemodynamic data were noted at 30 min, during obtuse marginal grafting, 1, 6, 12, and 24 h after surgery. Heart rate (HR), mean arterial pressure (MAP), pulmonary capillary wedge pressure (PCWP), cardiac index (CI), systemic vascular resistance index (SVRI) and pulmonary vascular resistance index (PVRI), left ventricular stroke work index (LVSWI) and right ventricular stroke work index (RVSWI), mixed venous oximetry (SvO₂), and lactate were measured.

Statistical Analysis Used:

Chi-square and Student's t-test.

Results:

The HR, MAP, PCWP, SVRI, and PVRI were lower in Group I when compared to Group II. Group I patients showed a statistically significant increase in LVSWI, RVSWI, and CI, when compared to Group II. Comparatively, Group I patients maintained higher SvO₂ and lower lactate levels. Duration of ventilation, Intensive Care Unit (ICU), and hospital stay were lower in Group I.

Conclusions:

Levosimendan was associated with statistically significant increase in indices of contractility (CI, LVSWI, and RVSWI) and decrease in PCWP during and after OPCAB. Levosimendan group had lower incidence of atrial fibrillation, shorter length of ICU, and hospital stay.

Early Left and Right Ventricular Response to Aortic Valve Replacement

BACKGROUND

The immediate effect of aortic valve replacement (AVR) for aortic stenosis on perioperative myocardial function is unclear. Left ventricular (LV) function may be impaired by cardioplegia-induced myocardial arrest and ischemia-reperfusion injury, especially in patients with LV hypertrophy. Alternatively, LV function may improve when afterload is reduced after AVR. The right ventricle (RV), however, experiences cardioplegic arrest without benefiting from improved loading conditions. Which of these effects on myocardial function dominate in patients undergoing AVR for aortic stenosis has not been thoroughly explored. Our primary objective is thus to characterize the effect of intraoperative events on LV function during AVR using echocardiographic measures of myocardial deformation. Second, we evaluated RV function.

METHODS

In this supplementary analysis of 100 patients enrolled in a clinical trial (NCT01187329), 97 patients underwent AVR for aortic stenosis. Of these patients, 95 had a standardized intraoperative transesophageal echocardiographic examination of systolic and diastolic function performed before surgical incision and repeated after chest closure. Echocardiographic images were analyzed off-line for global longitudinal myocardial strain and strain rate using 2D speckle-tracking echocardiography. Myocardial deformation assessed at the beginning of surgery was compared with the end of surgery using paired t tests corrected for multiple comparisons.

RESULTS

LV volumes and arterial blood pressure decreased, and heart rate increased at the end of surgery. Echocardiographic images were acceptable for analysis in 72 patients for LV strain, 67 for LV strain rate, and 54 for RV strain and strain rate. In 72 patients with LV strain images, 9 patients required epinephrine, 22 required norepinephrine, and 2 required both at the end of surgery. LV strain did not change at the end of surgery compared with the beginning of surgery (difference: 0.7 [97.6% confidence interval, -0.2 to 1.5]%; P = 0.07), whereas LV systolic strain rate improved (became more negative) (-0.3 [-0.4 to -0.2] s; P < 0.001). In contrast, RV systolic strain worsened (became less negative) at the end of surgery (difference: 4.6 [3.1 to 6.0]%; P < 0.001) although RV systolic strain rate was unchanged (0.0 [97.6% confidence interval, -0.1 to 0.1]; P = 0.83).

CONCLUSIONS

LV function improved after replacement of a stenotic aortic valve demonstrated by improved longitudinal strain rate. In contrast, RV function, assessed by longitudinal strain, was reduced.

Comparison of levosimendan and nitroglycerine in patients undergoing coronary artery bypass graft surgery

Background:

Levosimendan a calcium ion sensitizer improves both systolic and diastolic functions. This novel lusitropic drug has predictable antiischemic properties which are mediated via the opening of mitochondrial adenosine triphosphate-sensitive potassium channels. This action of levosimendan is beneficial in cardiac surgical patients as it improves myocardial contractility, decreases systemic vascular resistance (SVR), and increases cardiac index (CI) and is thought to be cardioprotective. We decided to study whether levosimendan has any impact on the outcomes such as the duration of ventilation, the length of Intensive Care Unit (ICU) stay, and the hospital stay when compared with the nitroglycerine (NTG), which is the current standard of care at our center.

Materials and Methods:

Forty-seven patients undergoing elective coronary artery bypass surgery were randomly assigned to two groups receiving either levosimendan or NTG. The medications were started before starting surgery and continued until 24 h in the postoperative period. Baseline hemodynamic parameters were evaluated before beginning of the operation and then postoperatively at 3 different time intervals. N-terminal fragment of pro-brain natriuretic peptide (NT-proBNP) levels were also measured in both groups.

Results:

In comparison to the NTG group, the duration of ventilation and length of ICU stay were significantly less in levosimendan group (P < 0.05, P = 0.02). NT-proBNP level analysis showed a slow rising pattern in both groups and a statistically significant rise in the levels was observed in NTG group (P = 0.03, P = 0.02) in postoperative period when compared to levosimendan group of patients.

Conclusion:

Levosimendan treatment in patients undergoing surgical revascularization resulted in improved CI, decreased SVR and lower heart rate. And, thereby the duration of ventilation and length of ICU stay were significantly less in this group of patients when compared with NTG group.

Local Anaesthetic Toxicity after Bilateral Thoracic Paravertebral Block in Patients Undergoing Coronary Artery Bypass Surgery

We conducted a small pilot observational study of the effects of bilateral thoracic paravertebral block (BTPB) as an adjunct to perioperative analgesia in coronary artery bypass surgery patients. The initial ropivacaine dose prior to induction of general anaesthesia was 3 mg/kg, which was followed at the end of the surgery by infusion of ropivacaine 0.25% 0.1 ml/kg/hour on each side (e.g. total 35 mg/hour for a 70 kg person). The BTPB did not eliminate the need for supplemental opioids after CABG in the eight patients studied. Moreover, in spite of boluses that were within the manufacturer's recommendation for epidural and major nerve blocks, and an infusion rate that was only slightly higher than what appeared to be safe for epidural infusion, potentially toxic total plasma ropivacaine concentrations were common. We also could not exclude the possibility that the high ropivacaine concentrations were contributing to postoperative mental state changes in the postoperative period. Also, one patient developed local anaesthetic toxicity after the bilateral paravertebral dose. As a result, the study was terminated early after four days. The question of whether paravertebral block confers benefits in cardiac surgery remains unanswered. However, we believe that the bolus dosage and the injection rate we used for BTPB were both too high, and caution other clinicians against the use of these doses. Future studies on the use of BTPB in cardiac surgery patients should include reduced ropivacaine doses injected over longer periods.

Anti-inflammatory effects of propofol during cardiopulmonary bypass: a pilot study

Introduction:

Propofol has been suggested as a useful adjunct to cardiopulmonary bypass (CPB) because of its potential protective effect on the heart mediated by a decrease in ischemia-reperfusion injury and inflammation at clinically relevant concentrations. In view of these potentially protective properties, which modulate many of the deleterious mechanism of inflammation attributable to reperfusion injury and CPB, we sought to determine whether starting a low dose of propofol infusion at the beginning of CPB would decrease inflammation as measured by pro-inflammatory markers.

Materials and Methods:

We enrolled 24 patients undergoing elective coronary artery bypass graft (CABG). The study group received propofol at rate of 120 mcg/kg/min immediately after starting CPB and was maintained throughout the surgery and for the following 6 hours in the intensive care unit (ICU). The control group received propofol dose of 30-50 mcg/kg/min which was started at the time of chest closure with wires and continued for the next 6 hours in the ICU. Interleukins (IL) -6, -8 and -10 and tumor necrosis factor alpha (TNFalpha) were assayed.

Result:

The most significant difference was in the level of IL-6 which had a P value of less than 0.06. Starting a low dose propofol early during the CPB was not associated with significant hemodynamic instability in comparison with the control group.

Conclusion:

Our study shows that propofol may be suitable as an anti-inflammatory adjunct for patients undergoing CABG.

Use of Tissue Doppler Imaging following Coronary Artery Bypass Surgery

This study assessed the effect of coronary artery bypass grafting (CABG) on myocardial systolic functions using tissue Doppler imaging (TDI). Fourteen patients (three women and 11 men) who had undergone isolated coronary bypass surgery were included in the study. Their mean age was 61 ± 8 years. TDI systolic velocity measures were obtained from four different sites on the left ventricular wall (anterior, septal, lateral and inferior) at the papillary muscle level in the parasternal short axis view before CABG, and then at 1 and 6 weeks post-operatively. There were significant increases in the myocardial wall velocities at all left ventricular sites 1 week after CABG. This increase persisted to week 6 after CABG, but the velocities were lower than week 1 values. We conclude that the ischaemic myocardium responded to surgical revascularization with marked increases in myocardial segmental systolic velocities in the early post-operative period.

Plasma levels of growth differentiation factor-15 are associated with myocardial injury in patients undergoing off-pump coronary artery bypass grafting

Growth differentiation factor-15 (GDF-15) has recently emerged as a risk predictor in patients with cardiovascular diseases. We therefore aimed to investigate the role of GDF-15 in the occurrence of cardiac injury during off-pump coronary artery bypass grafting (OPCAB). 55 consecutive patients with coronary artery diseases were recruited in this prospective, observational study. All patients were operated for OPCAB surgery. Serial blood samples were collected preoperatively, 12 hours and 36 hours after surgery. GDF-15, together with C-reactive protein, cardiac troponin I, creatine kinase MB and N-terminal pro B-type natriuretic peptide levels in plasma were measured at each time-point. GDF-15 levels increased significantly at 12 hours after surgery, attaining nearly 2.5 times the baseline levels (p < 0.001). Postoperative GDF-15 levels correlated positively with cTnI (p = 0.003) and EuroSCORE II (p = 0.013). According to the ROC curves, postoperative plasma GDF-15 was found to be the best biomarker to predict perioperative cardiac injury, compared with cTnI, CK-MB and EuroSCORE II. Circulating GDF-15 is a promising novel biomarker for identifying perioperative myocardial injury in patients undergoing OPCAB.

Right Ventricular Depression After Cardiopulmonary Bypass for Valvular Surgery

OBJECTIVE

To assess if right ventricular (RV) dysfunction is associated with increased mortality after cardiac surgery.

DESIGN

Post-hoc analysis of a single-center double-blind randomized controlled trial.

SETTING

University hospital.

PARTICIPANTS

A total of 120 patients undergoing simple or complex valvular surgery.

INTERVENTIONS

Patients were randomized to receive intravenous amiodarone or placebo intraoperatively. As secondary analysis, patients were divided into those requiring or not requiring postoperative inotropic agents.

MEASUREMENTS AND MAIN RESULTS

After cardiopulmonary bypass (CPB), there were significant increases in heart rate, cardiac index, systolic and mean arterial pressures, central venous pressure and pulmonary capillary wedge pressure with reduction in systemic vascular resistance (p<0.05). Right ventricular end-systolic area became larger in those without inotropes and tricuspid annular plane systolic excursion was reduced in all patients; mitral annular systolic velocities were higher in patients receiving inotropes. Both right- and left-sided Doppler signals were altered significantly after CPB, which may be attributed to increased filling pressure. Inotropic agents were required in 56 patients after CPB (47%). The use of inotropic agents was associated with increased left and right atrial velocities (p<0.05). There were no differences in postoperative complications between groups; however, the number of deaths at 6 years was increased in patients who received inotropes after CPB (p = 0.0247).

CONCLUSIONS

The increases in right-sided dimensions after CPB are associated with reduction in RV function and increased biventricular filling pressure, suggesting worsening biventricular function and interventricular dependence. Inotropic medications were associated with unaltered RV dimensions and increased biatrial activity.

Unexpected thrombus migration obstructing the right coronary ostium after thoracic aorta graft replacement

Unexpected and reversible causes of ventricular dysfunction requiring a prompt second surgical procedure to restore the cardiac function should always be sought before the initiation of positive inotropic support. We report a case of obstruction of the right coronary ostium by an organized thrombus that had migrated retrogradely from the false lumen of a dissected aortic aneurysm. The resultant ventricular dysfunction hindered separation from cardiopulmonary bypass. Prompt recognition was done by transesophageal echocardiography and a second surgical procedure was immediately performed to remove the thrombus before irreversible ventricular dysfunction occurred.

Myocardial ischemic conditioning: Physiological aspects and clinical applications in cardiac surgery

Ischemia-reperfusion is a major determinant of myocardial impairment in patients undergoing cardiac surgery. The main goal of research in cardioprotection is to develop effective techniques to avoid ischemia-reperfusion lesions. Myocardial ischemic conditioning is a powerful endogenous cardioprotective phenomenon. First described in animals in 1986, myocardial ischemic conditioning consists of applying increased tolerance of the myocardium to sustained ischemia by exposing it to brief episodes of ischemia-reperfusion. Several studies have sought to demonstrate its effective cardioprotective action in humans and to understand its underlying mechanisms. Myocardial ischemic conditioning has two forms: ischemic preconditioning (IPC) when the conditioning stimulus is applied before the index ischemia and ischemic postconditioning when the conditioning stimulus is applied after it. The cardioprotective action of ischemic conditioning was reproduced by applying the ischemia-reperfusion stimulus to organs remote from the heart. This non-invasive manner of applying ischemic conditioning has led to its application in clinical settings. Clinical trials for the different forms of ischemic conditioning were mainly developed in cardiac surgery. Many studies suggest that this phenomenon can represent an interesting adjuvant to classical cardioprotection during on-pump cardiac surgery. Ischemic conditioning was also tested in interventional cardiology with interesting results. Finally, advances made in the understanding of mechanisms that underlie the cardioprotective action of ischemic conditioning have paved the way to a new form of myocardial conditioning which is pharmacological conditioning.

Corrected right ventricular end-diastolic volume and initial distribution volume of glucose correlate with cardiac output after cardiac surgery

PURPOSE

Appropriate adjustment of cardiac preload is essential to maintain cardiac output (CO), especially in patients after cardiac surgery. This study was intended to determine whether index of right ventricular end-diastolic volume (RVEDVI), corrected RVEDVI using ejection fraction (cRVEDVI), index of initial distribution volume of glucose (IDVGI), or cardiac filling pressures are correlated with cardiac index (CI) following cardiac surgery in the presence or absence of arrhythmias.

METHODS

Eighty-six consecutive cardiac surgical patients were studied. Patients were divided into two groups: the non-arrhythmia (NA) group (n = 72) and the arrhythmia (A) group (n = 14). Three sets of measurements were performed: on admission to the ICU and daily on the first 2 postoperative days. The relationship between each cardiac preload variable and cardiac index (CI) was evaluated. A p value less than 0.05 indicated statistically significant differences.

RESULTS

Each studied variable was not different between the two groups immediately after admission to the ICU. cRVEDVI had a linear correlation with CI in both group (NA group: r = 0.67, n = 216, p < 0.001; A group: r = 0.77, n = 42, p < 0.001), but RVEDVI had a poor correlation with CI (NA group: r = 0.27, n = 216, p < 0.001; A group: r = 0.19, n = 42, p = 0.036). IDVGI had a linear correlation with CI (NA group: r = 0.49, n = 216, p < 0.001; A group: r = 0.61, n = 42, p < 0.001), Cardiac filling pressures had no correlation with CI.

CONCLUSION

Our results demonstrated that cRVEDVI and IDVGI were correlated with CI in the presence or absence of arrhythmias. cRVEDVI and IDVGI have potential as indirect cardiac preload markers following cardiac surgery.

Decreased incidence of low output syndrome with a switch from tepid to cold continuous minimally diluted blood cardioplegia in isolated coronary artery bypass grafting

OBJECTIVES

The optimal temperature for blood cardioplegia remains unclear.

METHODS

A retrospective analysis was performed on 138 patients undergoing isolated myocardial revascularization by a single surgeon in our institution over a period of 2 years. Patients operated on early in the study period received tepid (29°C) continuous minimally diluted blood cardioplegia (minicardioplegia), delivered in an antegrade continuous fashion. Later, our surgeon began using cold (7°C) blood minicardioplegia in all patients. Data pertaining to clinical outcomes and postoperative biochemical data were obtained, and the two groups were compared.

RESULTS

Low cardiac output syndrome, defined as the need for intra-aortic balloon pump counter pulsation or inotropic medication for haemodynamic instability, was more frequent in the tepid cardioplegia group than in the cold cardioplegia group (16.0 vs 2.4%, P = 0.006). There was no difference in the maximal serum creatine kinase MB between the two groups (cold 25.4 ± 3.21 μg/ml vs tepid 36.5 ± 7.10 μg/ml, P = 0.62), in the rates of perioperative myocardial infarction (cold 1.2% vs tepid 6.0%, P = 0.15) and the need for postoperative insertion of an intra-aortic balloon pump (cold 4.8% vs tepid 0.0%, P = 0.3). There was no other statistically significant difference between the two groups in the measured parameters.

CONCLUSIONS

A higher rate of low cardiac output syndrome in the tepid cardioplegia group suggests inferior myocardial protection with the tepid cardioplegia. Cold cardioplegia may provide better protection than tepid cardioplegia when minicardioplegia is used.

Role of metalloproteinases and tissue inhibitors of metalloproteinases during cardiopulmonary bypass in rats

Matrix metalloproteinases (MMPs) and the tissue inhibitors of matrix metalloproteinases (TIMPs) regulate matrix remodeling in the heart. Changes in synthesis and release of MMPs and TIMPs are observed after extracorporeal circulation (ECC). Thus, MMPs and TIMPs are supposed to be involved in ECC-mediated cardiac dysfunction. The aim was to examine the role of MMPs and TIMPs in ECC-mediated cardiac dysfunction. Extracorporeal circulation was instituted in rats for 60 min at a flow rate of 120 ml/kg/min. Three groups (n = 10) were studied: group CAO: 60 min ECC without aortic cross-clamping, group CAC: 60 min ECC including 30 min aortic cross-clamping (crystalloid Inzolen(®) cardioplegia), and group CAB: 60 min ECC including 30 min aortic cross-clamping (blood cardioplegia). Left ventricular (LV) function was measured with conductance catheter. Matrix metalloproteinase-activity was determined by zymography and TIMP activity was determined by reverse zymography. Gene expression of MMPs and TIMPs was determined by real-time polymerase chain reaction. Sixty minutes after weaning from bypass, there was a preserved LV function in the CAO and CAB group and an impaired LV function in the CAC group. We observed an increased myocardial activity and an increased myocardial messenger RNA expression of MMP-2, MMP-9, TIMP-1, and TIMP-4 in all ECC groups, when compared with sham animals. With regard to enzyme activity, there was an imbalance of MMP/TIMP ratio leading to an increased activity of MMP in the CAC group. In terms of gene expression, there was an imbalance of MMP-2/TIMP-4 ratio leading to an increased expression of MMP-2 in the CAC group. MMP-2 contributes to myocardial reperfusion injury in this in vivo model of ECC with cardioplegic arrest.

Postischemic infusion of sivelestat sodium hydrate, a selective neutrophil elastase inhibitor, protects against myocardial stunning in swine

PURPOSE

It seems controversial whether or not neutrophil elastase inhibitors are effective in attenuating myocardial ischemia/reperfusion injury. We thus investigated possible protective effects of sivelestat, a neutrophil elastase inhibitor, against myocardial stunning i.e., prolonged myocardial dysfunction following a brief episode of ischemia.

METHODS

Swine were divided into control group (group C), low-dose sivelestat group (group L), and high-dose sivelestat group (group H) (n = 7 for each group). All the swine were subjected to myocardial ischemia through ligation of the left anterior descending (LAD) coronary artery for 12-min, followed by 90-min reperfusion. Sivelestat was infused intracoronally at concentrations of 6 and 60 mg/ml throughout the reperfusion period in groups L and H, respectively, while saline was infused in the group C. Heart rate (HR), left ventricular developed pressure (LVdP), maximum rate of LVdP (LVdP/dt (max)), LV end-diastolic pressure (LVEDP), percentage of segment shortening (%SS, an index of regional myocardial contractility), and coronary venous interleukin-6 concentration in the LAD perfusion area were measured before ischemic induction and during reperfusion.

RESULTS

The ischemia/reperfusion insult did not cause any significant changes in HR, LVdP, LVdP/dt (max), and LVEDP in all groups. However, it significantly reduced %SS in the LAD perfusion area and increased the interleukin-6 concentration in group C. Those changes in %SS and the interleukin-6 concentration were both greatly attenuated, but not prevented, in groups L and H.

CONCLUSION

Sivelestat presumably attenuates myocardial contractile dysfunction due to myocardial stunning by inhibiting neutrophil-derived elastase, thereby suppressing the production of interleukin-6 in activated neutrophils.

Infusion of hypertonic saline/starch during cardiopulmonary bypass reduces fluid overload and may impact cardiac function

OBJECTIVE

Peri-operative fluid accumulation resulting in myocardial and pulmonary tissue edema is one possible mechanism behind post-operative cardiopulmonary dysfunction. This study aimed to confirm an improvement of cardiopulmonary function by reducing fluid loading during an open-heart surgery.

MATERIALS AND METHODS

Forty-nine elective CABG patients were randomized to an intraoperative infusion of hypertonic saline/hydroxyethyl starch (HSH group) or Ringer's solution (CT group). Both groups received 1 ml/kg/h of the study solution for 4 h after baseline values were obtained (PICCO transpulmonary thermodilution technique). Net fluid balance (NFB), hemodynamic and laboratory parameters were measured.

RESULTS

NFB was four times higher in the CT group compared with the HSH group during the first 6 h post-operatively. The total fluid gain until the next morning was lower in the HSH group, 2993.9 (938.6) ml, compared with the CT group, 4298.7 (1059.3) ml (P<0.001). Normalized values (i.e., %-changes from the baseline) of the cardiac index and the global end diastolic volume index increased post-operatively in both groups. Both parameters were significantly higher at 6 h in the HSH group compared with CT group (P=0.002 and 0.005, respectively). Normalized values of the intrathoracic blood volume index were lower in the HSH group at 6 h post-operatively when compared with the CT group. The PaO(2)/FiO(2) ratio decreased similarly in both groups early post-operatively, but recovery tended to be more rapid in the HSH group. Although serum-sodium and serum-chloride levels were significantly higher in the HSH group, the acid-base parameters remained similar and within the normal range.

CONCLUSIONS

An intraoperative infusion of HSH during cardiac surgery contributes to reduced fluid loading and an improvement in the post-operative cardiac performance. No adverse effects of the HSH infusion were observed.

Postoperative Care of the Cardiac Surgical Patient

The subspecialty of interventional cardiology began in 1977. Since then, the discipline of interventional cardiology has matured rapidly, particularly with regards to ischemic heart disease. As a result, more patients are undergoing percutaneous catheter interventional therapy for ischemic heart disease and fewer patients are undergoing surgical myocardial revascularization. Those patients referred for surgical revascularization are generally older and have more complex problems. Furthermore, as the population ages more patients are referred to surgery for valvular heart disease. The result of these changes is a population of surgical patients older and sicker than previously treated.

Pyruvate-fortified cardioplegia evokes myocardial erythropoietin signaling in swine undergoing cardiopulmonary bypass

Pyruvate-fortified cardioplegia protects myocardium and hastens postsurgical recovery of patients undergoing cardiopulmonary bypass (CPB). Pyruvate reportedly suppresses degradation of the alpha-subunit of hypoxia-inducible factor-1 (HIF-1), an activator of the gene encoding the cardioprotective cytokine erythropoietin (EPO). This study tested the hypothesis that pyruvate-enriched cardioplegia evoked EPO expression and mobilized EPO signaling mechanisms in myocardium. Hearts of pigs maintained on CPB were arrested for 60 min with 4:1 blood-crystalloid cardioplegia. The crystalloid component contained 188 mM glucose + or - 24 mM pyruvate. After 30-min cardiac reperfusion with cardioplegia-free blood, the pigs were weaned from CPB. Left ventricular myocardium was sampled 4 h after CPB for immunoblot assessment of HIF-1alpha, EPO and its receptor, the signaling kinases Akt and ERK, and endothelial nitric oxide synthase (eNOS), an effector of EPO signaling. Pyruvate-fortified cardioplegia stabilized arterial pressure post-CPB, induced myocardial EPO mRNA expression, and increased HIF-1alpha, EPO, and EPO-R protein contents by 60, 58, and 123%, respectively, vs. control cardioplegia (P < 0.05). Pyruvate cardioplegia also increased ERK phosphorylation by 61 and 118%, respectively, vs. control cardioplegia-treated and non-CPB sham myocardium (P < 0.01), but did not alter Akt phosphorylation. Nitric oxide synthase (NOS) activity and eNOS content fell 32% following control CPB vs. sham, but pyruvate cardioplegia prevented these declines, yielding 49 and 80% greater NOS activity and eNOS content vs. respective control values (P < 0.01). Pyruvate-fortified cardioplegia induced myocardial EPO expression and mobilized the EPO-ERK-eNOS mechanism. By stabilizing HIF-1alpha, pyruvate-fortified cardioplegia may evoke sustained activation of EPO's cardioprotective signaling cascade in myocardium.

Effect of rectal diclofenac in reducing postoperative pain and rescue analgesia requirement after cardiac surgery

BACKGROUND

Adequate analgesic medication is mandatory after coronary artery bypass grafting (CABG) surgery. The aim of this study was to assess the analgesic efficacy, side effects, and need for rescue analgesia after CABG surgery comparing diclofenac and placebo rectal suppository.

METHODS

Thirty-seven consenting adults undergoing elective CABG surgery were randomly assigned in a double-blind fashion to receive either rectal diclofenac 100 mg (Group 1, n = 19) or placebo suppository (Group 2, n = 18) postoperatively, just after extubation. Both groups were given intravenous tramadol as a rescue analgesic. Pain scores in the two groups were assessed on a 10-cm visual analog scale at 0, 0.5, 1, 1.5, 2, 6, 12, 18, and 24 hours after suppository administration. Rescue analgesic consumption, sedation, nausea, and vomiting in both the groups were also recorded.

RESULTS

Twenty-four-hour tramadol consumption in Group 1 was 92.5 +/- 33.5 mg compared to 157.5 +/- 63.4 mg in Group 2 (P = 0.002). Patients in the placebo group had significantly greater pain scores 1.5 to 12 hours after extubation. Group 1 patients were significantly more awake compared to Group 2 (P < 0.05). The incidence of postoperative nausea was less in Group 1 than in Group 2 (P = 0.001). Though not statistically significant, three patients in Group 2 each had a single episode of vomiting, whereas no patient had vomiting in Group 1.

CONCLUSION

Rectal diclofenac suppository with tramadol provides adequate pain relief after cardiac surgery, and also reduces tramadol consumption and side effects commonly associated with tramadol.

Different characteristics of postoperative heart failure after surgery for aortic stenosis and coronary disease

OBJECTIVE

Postoperative heart failure (PHF) remains a major determinant of outcome after cardiac surgery. However, possible differences in characteristics of PHF after valve surgery and coronary surgery (CABG) have received little attention. Therefore, this issue was studied in patients undergoing aortic valve replacement (AVR) and CABG, respectively.

DESIGN

Three hundred and ninety-eight patients undergoing isolated AVR for aortic stenosis were compared with 398 patients, matched for age and sex, undergoing on-pump isolated CABG. Forty-five AVR and 47 CABG patients required treatment for PHF and these were studied in detail.

RESULTS

The AVR group had longer aortic cross-clamp time and higher rate of isolated right ventricular heart failure postoperatively. Myocardial ischemia during induction and perioperative myocardial infarction were more common in the CABG group. One-year mortality was 8.9% in the AVR group vs 25.5% in the CABG group (p = 0.05).

CONCLUSIONS

The incidence of PHF was similar in both groups but different characteristics were found. Isolated right ventricular failure and PHF precipitated by septicemia were more common in AVR patients. PHF was more clearly associated with myocardial ischemia and infarction in CABG patients, which could explain their less favorable survival.

Clevidipine: an ultra short-acting calcium channel antagonist for acute hypertension

OBJECTIVE

To review the safety, efficacy, and pharmacologic characteristics of clevidipine, a new ultra short-acting intravenous antihypertensive agent for the treatment of moderate-to-severe hypertension.

DATA SOURCES

A literature search was conducted through MEDLINE (1966-March 2009), International Pharmaceutical Abstracts (1970-March 2009), and EMBASE (1988-March 2009) using the search terms clevidipine, H324/38, hypertension, and hypertensive crisis.

STUDY SELECTION AND DATA EXTRACTION

Available studies, abstracts, and review articles published in English that evaluated the pharmacology, pharmacokinetics, safety, and clinical efficacy of clevidipine were reviewed and critically evaluated.

DATA SYNTHESIS

Clevidipine is a new third-generation dihydropyridine calcium-channel blocker available for intravenous management of moderate-to-severe hypertension. Clevidipine is an ultra short-acting, selective arteriolar vasodilator that acts similar to other L-type dihydropyridine calcium-channel blockers by inhibiting influx of extracellular calcium into the vascular smooth muscle. Its safety and efficacy have been primarily evaluated in the perioperative setting in patients undergoing cardiac surgery requiring management of elevated blood pressure. In comparison to most other intravenous antihypertensives, clevidipine has a rapid onset of action, is ultra short-acting, easily titratable with a predictable dose response, and is void of drug-drug interactions and need for dose adjustment in patients with hepatic or renal insufficiency, thus making it a valuable antihypertensive in both the intraoperative and critical care settings. In clinical trials, clevidipine was well tolerated at infusion rates from 2-32 mg per hour, for up to 72 hours.

CONCLUSIONS

Clevidipine is the first intravenous antihypertensive approved by the Food and Drug Administration in nearly a decade. Based on available published clinical trials, clevidipine appears to be safe and effective in the acute management of moderate-to-severe elevations in blood pressure and a viable alternative to other agents such as nitroglycerin, sodium nitroprusside, and nicardipine.

Randomized controlled trial on the cardioprotective effect of bone marrow cells in patients undergoing coronary bypass graft surgery

AIMS

This randomized study investigates whether bone marrow cells (BMCs) can reduce ischaemic injury during cardiac surgery.

METHODS AND RESULTS

Forty-four elective coronary artery bypass grafting patients were randomized to control group or BMCs group (whereby autologous BMCs were administered with each dose of cardioplegia antegradely into the coronaries). Troponin I and CK-MB were measured during the first 48 h after surgery and were not significantly different between the control and BMCs groups. The role of cardiopulmonary bypass (CPB) on the cardioprotective effects of BMCs was also studied using an in vitro model of stimulated ischaemia and reoxygenation on right atrial appendages obtained from controls either before or 10 min after the initiation of CPB. Bone marrow cells significantly reduced myocardial injury in muscles obtained prior to CPB. This effect was comparable with ischaemic preconditioning (IP), although their combination did not afford additional benefit. However, when muscles were harvested after CPB, myocardial injury in the ischaemic group alone was less, and BMCs or IP did not exert further protection.

CONCLUSION

Bone marrow cells did not afford additional benefit when used as an additive to cardioplegia during CPB. However, BMCs offer cardioprotection as potent as IP, when the heart is not subjected to stress, such as CPB, that per se can precondition the myocardium.

Pulse pressure and risk of adverse outcome in coronary bypass surgery

BACKGROUND

Among ambulatory patients, an increase in pulse pressure (PP) is a well-established determinant of vascular risk. The relationship of PP and acute perioperative vascular outcome among patients having coronary artery bypass graft (CABG) surgery is less well known.

METHODS

We conducted a prospective observational study involving 5436 patients having elective CABG surgery requiring cardiopulmonary bypass. Of these, 4801 met final inclusion criteria. Comprehensive data were captured for medical history, intraoperative and postoperative physiologic and laboratory measures, diagnostic testing, and clinical events. The relationship between preoperative hypertension (systolic, diastolic, PP) and ischemic cardiac and cerebral outcomes and death was assessed using multivariable logistic regression; P<0.05 was considered significant.

RESULTS

Nine hundred and seventeen patients (19.1%) had fatal and nonfatal vascular complications, including 146 patients (3.0%) with cerebral and 715 patients (14.9%) with cardiac events. In-hospital mortality occurred in 147 patients (3.1%). Among all blood pressure variables measured preoperatively, PP was most strongly associated with an increased risk of postoperative complications. PP increments of 10 mm Hg (above a threshold of 40 mm Hg) were associated with an increased risk of cerebral events (adjusted odds ratio: 1.12; 95% CI [1.002-1.28]; P=0.026). The incidence of a cerebral event and/or death from neurologic complications nearly doubled for patients with PP>80 mm Hg versus<or=80 mm Hg (5.5% vs 2.8%; P=0.004). PP more than 80 mm Hg was also found to be associated with cardiac complications, increasing the incidence of congestive heart failure by 52%, and death from cardiac cause by nearly 100% (P=0.003 and 0.006, respectively).

CONCLUSION

An increase in PP was independently and significantly associated with greater fatal and nonfatal adverse cerebral and cardiac outcomes in patients having CABG surgery. These findings highlight the associated risks of preoperative PP on acute postoperative vascular outcomes.

Patients after atrial switch operation for transposition of the great arteries can not increase stroke volume under dobutamine stress as opposed to patients with congenitally corrected transposition

BACKGROUND

Patients after atrial switch operation for transposition of the great arteries have limited exercise performance. Rigid atrial baffles may cause a relative preload reduction. Previous studies have had suboptimal control groups, which ideally should consist of patients with congenitally corrected transposition of the great arteries (ccTGA) without previous heart surgery, having a systemic right ventricle, but lacking rigid atrial baffles. Therefore the aim of this study was to test the impact of atrial baffles by comparing 12 atrial switch patients with 11 ccTGA patients.

METHODS AND RESULTS

Systemic right ventricular stroke volume (SV), heart rate, cardiac index, and other parameters were assessed during rest and dobutamine stress magnetic resonance imaging. The most important difference between the groups was that the atrial switch patients could not increase SV during stress, whereas ccTGA patients increased it significantly. There was no difference between groups in the rise of the cardiac index. Heart rate increased significantly more in atrial switch patients than in ccTGA patients.

CONCLUSIONS

The results support the hypothesis that atrial baffles restrict a rise in SV under dobutamine stress in patients after atrial switch operation for transposition of the great arteries.