Cardiac troponin T and troponin I release during coronary artery surgery using cold crystalloid and cold blood cardioplegia

Blood versus crystalloid cardioplegia during triple valve surgery: A single center experience

BACKGROUND

The efficacy of different cardioplegia solutions on outcomes of complex cardiac operations such as triple valve surgery (TVS) is scarce. Here we compared the outcomes in TVS patients receiving either crystalloid (Bretschneider) or blood (Calafiore) cardioplegia.

METHODS

Screening of our institutional database with prospectively entered data identified 471 consecutive patients (mean age 70.3 ± 9.2 years; 50.9% male), who underwent TVS (replacement or repair of aortic, mitral and tricuspid valve) between December 1994 and January 2013. In 277 patients, cardiac arrest was induced with HTK-Bretschneider solution (HTK, n = 277, 58.8%), whereas 194 received cold blood cardioplegia (BCP) according to Calafiore (n = 194, 41.2%). Comparisons of perioperative and follow up outcomes were made between cardioplegia groups.

RESULTS

Preoperative patient characteristics and comorbidities were equally balanced between groups. 30-days mortality was similar between groups (HTK: 16.2%; BCP: 18.2%; p = 0.619). Incidence of the cumulative endpoint (30days mortality, myocardial infarction (MI), arrhythmia, low cardiac output syndrome or need for permanent pacemaker implantation) was also comparable (HTK: 47.6%; BCP: 54.8%, p = 0.149). In patients with reduced left ventricular ejection fraction (LVEF <40%), 30days mortality was higher in the HTK group (HTK 18/71 22.5%; BCP 5/50 10%; p = 0.037). Five-year survival was similar between groups (52 ± 6% for HTK and 55 ± 5% for BCP patients). In-Hospital mortality was best predicted by length of surgery and reperfusion ratio. Decreased age, shorter bypass time, preserved LVEF and concomitant surgical procedures have been found to be protective from long-term mortality.

CONCLUSIONS

Myocardial protection with HTK shows equivalent outcomes compared to BCP during TVS. Patients with reduced left ventricular function may benefit from BCP during TVS.

Comparison of Bretschneider HTK and Blood Cardioplegia (4:1): A Prospective Randomized Study

BACKGROUND

We compared the effect of intermittent blood and histidine-tryptophan-ketoglutarate (HTK) solution of Bretschneider on myocardial histopathology and perioperative outcome.

METHODS

Forty adult cardiac surgery patients were grouped into two (n = 20 for each): (1) Intermittent blood cardioplegia (IBC): had repeated cold 4:1 blood cardioplegia and (2) HTK: had a single dose of cold HTK for cardioprotection. Creatine kinase (CK)-MB, Troponin-I (cTn-I), pH, and lactate were studied in coronary sinus blood before and after aortic cross-clamping (AXC) and systemic blood at postoperative 6th, 24th, and 48th hours. Myocardial biopsy was performed before and after AXC for light microscopy. Vacuolation, inflammation, edema, and glycogen were graded semiquantitatively (from 0 to 3). The myocardial apoptotic index was evaluated via the terminal deoxynucleotidyl transferase dUTP nick end labeling.

RESULTS

There were no differences in perioperative clinical outcomes between the groups. The coronary sinus samples after AXC were more acidotic (7.15 ± 0.14 vs. 7.32 ± 0.07, p = 0.001) and revealed higher CK-MB (21.0 ± 12.81 vs. 12.60 ± 11.80, p = 0.008) in HTK compared with IBC. The HTK had significantly a higher amount of erythrocyte suspension intraoperatively compared with IBC (0.21 ± 0.53 vs. 1.68 ± 0.93 U, p = 0.001). Microscopically, myocardial edema was more pronounced in HTK compared with IBC after AXC (2.25 ± 0.91 vs. 1.50 ± 0.04, p = 0.013). While a significant increase in the apoptotic index was seen after AXC in both groups (p = 0.001), no difference was detected between the groups (p = 0.417).

CONCLUSION

IBC and HTK have a similar clinical outcome and protective effect, except for more pronounced myocardial edema and increased need for intraoperative transfusion with HTK.

Myocardial Protection With Different Cardioplegia in Adult Cardiac Surgery: A Network Meta-Analysis

AIM

Cardioplegia is one of the most studied fields of myocardial protection during cardiac surgery. However, the most effective cardioplegia for protection in adult cardiac surgery remains unknown.

METHOD

PubMed and other databases were searched and a network meta-analysis with a Bayesian framework was performed. The primary outcomes were the serum concentrations of creatine kinase-myocardial band (CK-MB), cardiac troponin I, and cardiac troponin T (cTnT) at four time points. Several clinical outcomes were evaluated, including low output syndrome, myocardial infarction, and risk of early mortality. All studies that involved crystalloid cardioplegia without reference to St Thomas cardioplegia or histidine-tryptophan-ketoglutarate solution, and if the cardioplegia was used at a temperature between 4°C and 16°C were classified as cold crystalloid (cCCP) or cold blood cBCP cardioplegia. Warm blood cardioplegia (wBCP) was defined as the blood cardioplegia used at a temperature between 32°C and 37°C.

RESULTS

Forty-seven (47) studies with a total of 4,175 patients were included. Seven (7) cardioplegia solutions were used, including cold CCP or BCP, del Nido solution, histidine-tryptophan-ketoglutaratesolution, St Thomas cardioplegia, wBCP and warm terminal blood cardioplegia (wtBCP). The serum concentrations of CK-MB at 2 hours (mean difference [MD], 213.56; 95% confidence interval [CI], -25.79 to -1.59) and cTnT at 24 hours of wBCP (MD, -1.50; 95% CI, -2.69 to -0.31) were significantly lower than that of cCCP. There were no significant differences in other outcomes of these six cardioplegia solutions, when compared to cCCP.

CONCLUSIONS

The seven cardioplegia solutions analysed had similar myocardial protective effects after adult cardiac surgery, although wBCP had a lower CK-MB at 2 hours and lower cTnT at 24 hours.

Cold crystalloid versus warm blood cardioplegia in patients undergoing aortic valve replacement

Background

Myocardial protection techniques during cardiac arrest have been extensively investigated in the clinical setting of coronary revascularization. Fewer studies have been carried out of patients affected by left ventricular hypertrophy, where the choice of type and temperature of cardioplegia remain controversial. We have retrospectively investigated myocardial injury and short-term outcome in patients undergoing aortic valve replacement plus or minus coronary artery bypass grafting with using cold crystalloid cardioplegia (CCC) or warm blood cardioplegia (WBC).

Methods

From January 2015 to October 2016, 191 consecutive patients underwent aortic valve replacement plus or minus coronary artery bypass grafting in normothermic cardiopulmonary bypass. Cardiac arrest was obtained with use of intermittent antegrade CCC group (n=32) or WBC group (n=159), according with the choice of the surgeon.

Results

As compared with WBC group, in CCC group creatine-kinase-MB (CK-MB), cardiac troponin I (cTnI), aspartate aminotransferase (AST) release, and their peak levels, were lower during each time points of evaluation, with the greater statistically significant difference at time 0 (P<0.05, for all comparisons). A time 0, CK-MB/CK ratio >10% was 5.9% in CCC group versus 7.8% in WBC group (P<0.0001). At time 0 CK-MB/CK ratio >10% in patients undergoing isolated aortic valve replacement was 6.0% in CCC group versus 8.0% in WBC group (P<0.01). No any difference was found in perioperative myocardial infarction (0% versus 3.8%), postoperative (PO) major complications (15.6% versus 16.4%), in-hospital mortality (3.1% versus 1.3%).

Conclusions

In aortic valve surgery a significant decrease of myocardial enzymes release is observed in favor of CCC, but this difference does not translate into different clinical outcome. However, this study suggests that in presence of cardiac surgical conditions associated with significant left ventricular hypertrophy, i.e., the aortic valve disease, a better myocardial protection can be achieved with the use of a cold rather than a warm cardioplegia. Therefore, CCC can be still safely used.

Changes of cardiac troponin I and operative mortality of coronary artery bypass

Background

Recently, cardiac troponin I has been used to detect myocardial injury because of its superior cardiac specificity. However, there has been debate about the appropriate timing and cutoff level of cardiac troponin I to detect perioperative myocardial injury after coronary artery bypass grafting. The objective of this study was to define the relationship between operative mortality and changes in cardiac troponin I after isolated coronary artery bypass.

Patients and methods

A retrospective analysis was carried out on data of 218 isolated coronary artery bypass patients who were operated on between June 2009 and February 2012. All patients followed an institutional perioperative management protocol that included 6 cardiac troponin I measurements (preoperatively and 0, 12, 24, 36, and 48 h after coronary artery bypass). According to the patterns of cardiac troponin I, the patient cohort was divided into 2 groups. Group 1 was patients in whom cardiac troponin I levels decreased 24 h after the operation, and group 2 comprised the patients with cardiac troponin I levels that did not decrease or even increased after 24 h.

Results

The operative mortality was 4.1% (9/218). Group 2 showed significantly higher mortality (5/25, 20%) than group 1 (4/193, 2.1%).

Conclusion

An elevated cardiac troponin I level is common after coronary artery bypass. A persistently high level of cardiac troponin I after 24 h is an important predictor of operative mortality after coronary artery bypass surgery.

Is there any difference between blood and crystalloid cardioplegia for myocardial protection during cardiac surgery? A meta-analysis of 5576 patients from 36 randomized trials

Objective:

To compare the efficacy of blood versus crystalloid cardioplegia for myocardial protection in patients undergoing cardiac surgery.

Methods:

MEDLINE, EMBASE, CENTRAL/CCTR, SciELO, LILACS, Google Scholar and reference lists of relevant articles were searched for clinical studies that reported in-hospital outcomes after blood or crystalloid cardioplegia for myocardial protection during cardiac surgery procedures from 1966 to 2011. The principal summary measures were risk ratio (RR) for blood compared to crystalloid cardioplegia with 95% Confidence Interval (CI) and P values (considered statistically significant when <0.05). The RRs were combined across studies using the DerSimonian-Laird random effects model and fixed effects model using the Mantel-Haenszel model - both models were weighted. The meta-analysis was completed using the software Comprehensive Meta-Analysis version 2 (Biostat Inc., Englewood, New Jersey).

Results:

Thirty-six studies (randomized trials) were identified and included a total of 5576 patients (2834 for blood and 2742 for crystalloid). There was no significant difference between the blood and crystalloid groups in the risk for death (risk ratio [RR] 0.951, 95% CI 0.598 to 1.514, P=0.828, for both effect models) or myocardial infarction (RR 0.795, 95% CI 0.547 to 1.118, P=0.164, for both effect models) or low cardiac output syndrome (RR 0.765, 95% CI 0.580 to 1.142, P=0.094, for the fixed effect model; RR 0.690, 95% CI 0.480 to 1.042, P=0.072, for the random effect model). It was observed that there was no publication bias or heterogeneity of effects about any outcome.

Conclusion:

We found evidence that argues against any superiority in terms of hard outcomes between blood or crystalloid cardioplegia for myocardial protection during cardiac surgery.

Remote ischemic preconditioning reduces myocardial injury after coronary artery bypass surgery with crystalloid cardioplegic arrest

Remote ischemic preconditioning (RIPC) with transient upper limb ischemia reduces myocardial injury in patients undergoing on-pump coronary artery bypass grafting (CABG) with cross-clamp fibrillation or blood cardioplegia for myocardial protection. Whether or not such protection is still operative when standard crystalloid cardioplegic arrest is used is uncertain. Fifty-three consecutive, non-diabetic patients with triple-vessel disease and 64 +/- 12 years of age (mean +/- SD), who underwent elective CABG surgery with crystalloid (Bretschneider) cardioplegic arrest, were allocated in a prospective, randomized, single-blinded protocol to receive either a RIPC protocol (3 cycles of 5 min transient left upper arm ischemia induced by inflating a blood pressure cuff to 200 mmHg with 5 min of reperfusion) or control, respectively, after induction of anesthesia. Cardiac troponin I (cTnI) concentration was measured preoperatively and over 72 h postoperatively, and the area under the curve (AUC) was calculated. Peak postoperative cTnI concentration was significantly reduced from 13.7 +/- 7.7 ng/mL in controls to 8.9 +/- 4.4 ng/mL in RIPC (P = 0.008). Mean cTnI concentration was significantly lower at 6, 12, 24, and 48 h after surgery (ANOVA; P < 0.0001) in the RIPC patients (N = 27) than in controls (N = 26), resulting in a 44.5% reduction of cTnI (AUC at 72 h). RIPC by repetitive inflation of a cuff around the left upper arm before surgery enhances myocardial protection in patients undergoing CABG surgery with antegrade cold crystalloid cardioplegia.

Cold blood cardioplegia reduces the increase in cardiac enzyme levels compared with cold crystalloid cardioplegia in patients undergoing aortic valve replacement for isolated aortic stenosis

OBJECTIVES

Cardiac arrest during cardiac surgery is most commonly induced by cold blood or cold crystalloid cardioplegia. The results from clinical studies are divergent regarding which of the 2 solutions provides better myocardial protection. This might be explained by several factors. Both heterogeneity in disease for the included patients and the fact that most studies are retrospective in design and that patients with coronary artery disease with different degrees of myocardial ischemia are included might explain these findings. To circumvent these potentially confounding factors, we included in a prospective randomized study only patients undergoing aortic valve replacement for aortic stenosis without other significant cardiac disease. Patients were randomized to antegrade cold crystalloid or cold blood cardioplegia.

METHODS

Eighty patients with aortic stenosis undergoing aortic valve replacement without significant coronary artery stenosis or other significant concomitant heart valve disease were included in the study. They were randomized to either antegrade cold blood or cold crystalloid cardioplegic solution delivered through the coronary ostia every 20 minutes throughout the period of aortic crossclamping. Maximum postoperative creatine kinase isoenzyme MB and troponin-T levels, well-established markers of myocardial damage, were compared between the 2 groups.

RESULTS

Both maximum postoperative creatine kinase isoenzyme MB and troponin-T levels were significantly higher by approximately 100% in the cohort of patients receiving crystalloid compared with blood cardioplegia. Only in the group of patients receiving cold crystalloid cardioplegia was there a positive correlation between cardiac enzyme levels and crossclamp time.

CONCLUSION

Antegrade cold blood cardioplegia provides better myocardial protection than cold crystalloid cardioplegia in patients undergoing aortic valve replacement.

Evaluation of myocardial metabolism with microdialysis after protection with cold blood- or cold crystalloid cardioplegia. A porcine model

OBJECTIVES

There has been a considerable change in the patient population referred for cardiac surgery in the last decade. More complex and marginal patients require optimized myocardial protection. An insufficient cardioplegic procedure results in anaerobic metabolism during cardiac arrest with subsequent lactate accumulation. Increased lactate level is regarded as a predictor for low cardiac output syndrome. In an acute porcine model we examined two standard cardioplegic methods. Myocardial microdialysis was used to investigate the metabolism during cardioplegic arrest and in the reperfusion period.

METHODS

Twelve domestic pigs were randomly chosen to receive either cold blood-or cold crystalloid cardioplegia. After midline sternotomy two microdialysis probes were implanted in two different regions of the heart. Cardiopulmonary bypass was initiated, aorta was clamped, and antegrade cardioplegia was delivered. These conditions were maintained for 90 min. Subsequent to myocardial reperfusion the animals were observed for 180 min. Microdialysis and plasma markers to characterize myocardial metabolism, and plasma markers for myocardial failure and necrosis were obtained every 30 min.

RESULTS

Lactate concentrations were significantly increased in the cold crystalloid cardioplegia group compared to the cold blood cardioplegia group, in tissue dialysate (p < 0.001) as well as in serum (p = 0.018). Pyruvate concentrations in the dialysate were significantly increased in the cold crystalloid cardioplegia group compared to the cold blood cardioplegia group (p = 0.008). There were no significant differences in dialysate concentrations of glycerol. Plasma markers for myocardial failure (Brain Natriuretic Peptide) and for myocardial necrosis (Cardiac Troponin T) showed no differences between the groups.

CONCLUSION

The results indicate that cold blood cardioplegia offers superior protection of the heart, in terms of more rapid normalization of myocardial metabolism. The microdialysis technique seems to have a high sensitivity and ability to detect even minor metabolic changes. This enhances the possibility of designing a myocardial protection, which might lower morbidity and mortality risk.

Myocardial cooling with ice-slush provides no cardioprotective effects in aortic valve replacement

OBJECTIVES

Topical cooling of the heart with ice-slush has been widely used for myocardial protection. No prospective, randomized study has evaluated the effect of ice-slush on acknowledged markers (CK-MB, troponin-T) of myocardial damage during aortic valve replacement (AVR). This was the first aim of the present study. A second aim was to examine whether performing a study per se reduced myocardial damage.

DESIGN

Sixty patients undergoing AVR were receiving cold crystalloid antegrade cardioplegia every 20 min. Thirty patients were randomized to achieve additional topical cooling with ice-slush. CK-MB and troponin-T were compared between groups as well as to a group of patients undergoing AVR immediately prior to the study.

RESULTS

There were no significant differences in myocardial markers between patients with or without ice-slush. However, we found significantly higher levels of troponin-T and CK-MB in patients undergoing AVR prior to start of the study.

CONCLUSIONS

Topical cooling with ice-slush does not provide additional cardioprotective effects. Comparison with an historical cohort indicates that administration of crystalloid cardioplegia following a rigid protocol might reduce myocardial damage.

Is blood superior to crystalloid cardioplegia? A meta-analysis of randomized clinical trials

BACKGROUND

Many small, randomized, controlled trials have evaluated the effectiveness of blood as compared with crystalloid cardioplegia for myocardial protection during cardiac surgery. Blood cardioplegia provides a closer approximation to normal physiology, which may translate into measurable clinical benefits. This meta-analysis describes the effectiveness of blood cardioplegia in lowering adverse postoperative outcomes.

METHODS AND RESULTS

MEDLINE, EMBASE, and the Cochrane registry of controlled trials were searched for clinical trials. The search was restricted to peer-reviewed English language publications of randomized controlled trials that primarily compared blood and crystalloid cardioplegia in adult patients. Each trial was blindly assessed and abstracted by 2 reviewers. The primary outcomes were: low output syndrome (LOS), myocardial infarction (MI), and death. Surrogate outcomes included postoperative creatinine kinase MB (CKMB) increase. Random effects summary odds ratio (OR) for binary outcomes, and weighted mean difference for continuous outcomes were calculated. A total of 34 trials were included. The majority of trials were conducted in patients undergoing elective CABG surgery (n=18). The incidence of LOS was decreased significantly with blood cardioplegia (OR, 0.54; 95% confidence interval [CI], 0.34 to 0.84; P=0.006; 879 patients, 10 trials). The incidence of MI and death were similar between treatment groups (MI: OR, 0.78; 95% CI, 0.54 to 1.13; 4316 patients, 23 trials) (death: OR, 0.80; 95% CI, 0.46 to 1.40; 4022 patients, 17 trials). CKMB release after surgery at 24 hours was reduced with blood cardioplegia (5.9 U/L; 95% CI, 1.6 to 10.2; P=0.007; 821 patients, 7 trials).

CONCLUSIONS

Blood cardioplegia provides superior myocardial protection as compared with crystalloid cardioplegia, including lower rates of LOS, and early CKMB increase, whereas the incidence of myocardial infarction and death are similar.

Terminal warm blood cardioplegia in mitral valve replacement: prospective study

Terminal warm blood cardioplegia has had a profound impact on cardiac surgery, especially in coronary artery bypass surgery, but there have been few studies on its use in mitral valve replacement. The purpose of this study was to determine whether terminal warm blood cardioplegia offers any advantages in mitral valve replacement. Forty patients with mitral valve disease were prospectively randomized to one of two groups of 20 with different techniques of myocardial protection: group A had cold blood cardioplegia, and group B had cold blood cardioplegia with terminal warm blood cardioplegia. Intraoperative and postoperative variables were used to assess primary outcomes. Postoperative troponin T release was measured as a secondary outcome. Improved spontaneous recovery of sinus rhythm was observed in group B, but the difference was not significant. The maximum doses of inotropics, duration of inotropic support, intensive care unit stay, and postoperative left ventricular ejection fraction were similar in both groups. Troponin T release at 0 and 6 h postoperatively was not different between the two groups. This study did not find any benefit of terminal warm blood cardioplegia in either clinical outcome or troponin T release after mitral valve replacement.

Cardiac troponins as biomarkers of drug- and toxin-induced cardiac toxicity and cardioprotection

Cardiac troponin T and I (cTnT, cTnI) are sensitive biochemical markers of myocardial cell necrosis and have been adopted as the gold standard tests for acute myocardial infarction. Subtle elevations in cTn above the detection limits of the currently available commercial assays confers poor prognosis. These markers are superior to classical enzyme markers of necrosis due to their cardiospecificity. The diagnosis of drug-induced cardiac toxicity using the classical enzymes is problematic due to the high elevations of these markers in skeletal muscle necrosis. cTnT and cTnI are now being adopted as sensitive biomarkers of drug-induced cardiac toxicity.

A comparison of 250 and 500 mL of terminal warm blood cardioplegia after global myocardial ischemia: a prospective randomized study

BACKGROUND

Controlled reperfusion with terminal warm blood cardioplegia (TWBC) improves myocardial performance after global ischemia. However, the optimum volume required is unknown.

METHODS

Fifty patients undergoing elective coronary artery bypass graft surgery were prospectively randomized to receive either 250 or 500 mL of TWBC. During TWBC delivery, and for 10 minutes after cross-clamp removal, samples were taken from the aorta and coronary sinus to measure the hydrogen ion, lactate, and oxygen content.

RESULTS

At the end of TWBC delivery, the 500 mL group had significantly less hydrogen ion washout (p = 0.006) compared with the 250 mL group. Also, more hydrogen ions (p = 0.02) and lactate (p = 0.02) had been washed out during the entire period of TWBC delivery in the 500 mL group compared with the 250 mL, indicating better metabolic recovery. By 4 minutes after aortic cross-clamp removal, hydrogen ion and lactate washout, as well as oxygen extraction was similar in the two groups. However, the time to return to regular mechanical activity was prolonged in the 500 mL group, 5.8 (3) versus 4.6 (3) minutes in the 250 mL group (p = 0.05). Though there was no difference in postoperative Troponin T levels, eight patients in the 500 mL group versus four in the 250 mL group required ionotropic support (p = 0.1).

CONCLUSIONS

A total of 500 mL of hotshot achieves a better metabolic state after hotshot delivery. However, there is no clinical benefit or improvement in the postoperative Troponin T release suggesting that in a short ischemic time, 500 mL TWCB has a limited clinical benefit.

Cold blood cardioplegia versus cold crystalloid cardioplegia: A prospective randomized study of 1440 patients undergoing coronary artery bypass grafting

OBJECTIVES

A large number of experimental studies have indicated that blood cardioplegia might be superior to crystalloid cardioplegia for myocardial protection during ischemic arrest. However, no prospectively randomized studies of large patient series have been undertaken to prove potential differences in clinical course.

METHODS

Over a 52-month period, all patients undergoing on-pump coronary artery bypass operated on by 2 surgeons were prospectively randomized to receive either cold crystalloid cardioplegia (group C) or cold blood cardioplegia (group B) during aortic crossclamping.

RESULTS

Altogether, 1440 patients aged 37 to 89 years (median, 66 years) entered the study (group C, n = 719; group B, n = 721). The groups were comparable in all major demographic, preoperative, and operative variables. The clinical course turned out to be nearly identical for both groups. No statistically significant differences were seen concerning spontaneous sinus rhythm after aortic declamping, use of inotropic drugs or intra-aortic balloon pumping, postoperative ventilatory support, bleeding and rate of allogeneic blood transfusions, perioperative myocardial infarction, episodes of atrial fibrillation, stroke or minor neurologic dysfunction, renal function, infections, physical rehabilitation, or mortality. Also, in subgroups of patients at higher operative risk (female sex, age >70 years, unstable angina, diabetes, emergency operation, ejection fraction <0.50, crossclamping time >50 minutes, and EuroSCORE >4), no statistically significant differences could be demonstrated between the groups.

CONCLUSIONS

There were no significant differences whether myocardial protection was performed with cold blood cardioplegia or cold crystalloid cardioplegia during aortic crossclamping in patients undergoing coronary artery bypass grafting. The extra costs related to blood cardioplegia might be saved.

Cardiac marker responses to coronary artery bypass graft surgery with cardiopulmonary bypass and aortic cross-clamping

OBJECTIVE

To study several markers of myocardial injury in relation to aortic cross-clamping and cardiopulmonary bypass (CPB) after coronary artery bypass graft (CABG) surgery.

DESIGN

Prospective observational study.

SETTING

University hospital.

PARTICIPANTS

Thirty adult patients who underwent elective CABG surgery with aortic cross-clamping and CPB.

MEASUREMENTS AND MAIN RESULTS

Serum levels of interleukin-6 (IL-6), interleukin-8 (IL-8), troponin-T (TnT), myosin light chain I (MLCI), and MB isoenzyme of creatine kinase (CK-MB), as markers of myocardial injury, were measured after induction of anesthesia for baseline values, then again at the end of surgery and on postoperative days 1, 3, and 5. IL-6, IL-8, and CK-MB levels were significantly elevated in the early postoperative stage. TnT significantly increased from the end of surgery to postoperative day 5. MLCI increased also but later than TnT. Aortic cross-clamping time correlated positively with peak TnT (r = 0.51, p < 0.05), TnT level on postoperative day 1 (r = 0.69, p < 0.01), and MLCI level on postoperative day 5 (r = 0.45, p < 0.05). CPB time was correlated only with peak TnT (r = 0.47, p < 0.05).

CONCLUSIONS

The increase in TnT level is strongly related to aortic cross-clamping.

Cardiac troponin I: its contribution to the diagnosis of perioperative myocardial infarction and various complications of cardiac surgery

OBJECTIVE

To study the value of assaying cardiac troponin I (cTnI) for the early diagnosis of perioperative myocardial infarction (PMI) and various complications of cardiac surgery.

DESIGN

A prospective observational clinical study.

SETTING

Biochemical laboratory, anesthesia, and cardiac surgery department of Hôpital Broussais.

PATIENTS

Two hundred and sixty consecutive patients undergoing cardiac surgery.

INTERVENTIONS

All patients underwent coronary artery bypass grafting and/or valvular surgery under extracorporeal circulation. Per-operative and postoperative follow-up consisted of electrocardiogram, echocardiography (mainly by the transesophageal approach), and serial determinations of biochemical markers such as creatinine kinase-MB isoenzyme (CK-MB) and cTnI. PMI, new ST segment changes, and ventricular arrhythmias were considered postoperative adverse cardiac outcome.

MEASUREMENTS AND MAIN RESULTS

CTnI was measured before cardiopulmonary bypass (T0) and 12 and 24 hrs after (T12, T24). CK-MB was measured on arrival in the intensive care unit and on the first postoperative day (D1). Patients were divided into three groups according to the type of surgery: coronary artery bypass graft (CABG), valvular surgery (VS), or both procedures. The plasma CK-MB and cTnI concentrations were high in all patients after extracorporeal circulation because of aortic clamping or cardioplegia. The CK-MB and cTnI values were higher in the VS group than in the CABG group. Values peaked at T12 and fell by T24, except when PMI occurred. Eight patients developed a PMI. Patients with PMI had significantly higher cTnI levels at T12 and T24, and higher CK-MB values at D1 than patients without PMI. Cutoff values of cTnI for diagnosing PMI were >19 microg/L at T12 with 100% sensitivity and 73% specificity, and >36 microg/L at T24, with 100% sensitivity and 93% specificity. Lower cTnI values were highly suggestive of the absence of PMI after CABG and/or VS. Other complications such as ST segment changes, ventricular arrhythmias and cardiac failure were indicated by high cTnI levels at T12 and T24. Myocardial protective measures were associated with a nonsignificant increase in cTnI values.

CONCLUSIONS

CTnI is more sensitive and specific than CK-MB for diagnosing PMI and other forms of heart failure after cardiac surgery.

Predictive value of perioperative cardiac troponin I for adverse outcome in coronary artery bypass surgery

OBJECTIVES

Cardiac Troponin I (cTnI) is a well-known marker for myocardial damage in patients undergoing aorto-coronary bypass grafting (CABG) peaking 6-8 h after aortic declamping. The aim of this study was to evaluate cTnI release in the course of CABG procedures early, i.e. after the cessation of cardiopulmonary bypass (CPB) in order to recognize unstable cardiac function leading to hemodynamic deterioration and resulting in an adverse outcome (AO). AO is defined as the onset of myocardial infarction and/or death peri/postoperatively.

METHODS

Five-hundred and forty consecutive patients who underwent CABG were evaluated for cTnI release immediately prior to the induction of anesthesia (IND) and after termination of CPB (END). Standard CPB with ante/retrograde cold blood cardioplegia was used. Patients with any of the following criteria were excluded: (1), CABG within 7 days of myocardial infarction; (2), emergency operation for both unstable angina and for coronary occlusion at angioplasty; (3), CABG with concomitant surgical cardiac procedures; (4), preoperative renal dysfunction requiring hemodialysis; (5), redos. Troponin I was measured with the Stratus CS fluorometric enzyme immunoassay analyzer (Dade-Behring) running on site in the operation room (OR), so values of cTnI could be obtained within 15 min.

RESULTS

There were six deaths (1.1%) in the entire series, Q-wave myocardial infarction occurred in 19 patients (3.5%), AO was experienced by 21 patients (3.9%). The mean preoperative cTnI level was 0.04+/-0.17 ng/l (mean+/-standard deviation) for the entire group. The END cTnI level for the AO-group was 0.91+/-0.5 ng/l; for all other patients, this was 0.37+/-0.3 ng/l (P<0.001). Changes in intraoperative cTnI levels relative to time course showed a marked increase for the AO-group (0.0038+/-0.0035 ng/l*min) as compared with non-AO patients (0.0019+/-0.0015 ng/l*min; P=0.028). The receiver operating characteristic curve indicates a cTnI level at CPB-end of higher than 0.495 ng/l with an area under the curve of 0.83 as the optimal cut-off point for predicting AO with a sensitivity and specificity of 76.2%. Stepwise logistic regression analysis revealed END cTnI level (odds ratio, 17.24; P<0.001), CPB time (odds ratio, 1.03; P=0.001), female sex (odds ratio, 3.8; P=0.011) as significant independent predictors for AO. Age of over 70 years (P=0.8), Cleveland Clinic risk score (P=0.65), diabetes (P=0.26), elevated preoperative creatinine level (P=0.77), severe left ventricular dysfunction (P=0.51), the number of grafts performed (P=0.15), and change of intraoperative cTnI level relative to time course (P=0.94) did not reach statistical significance.

CONCLUSIONS

cTnI release as determined at the end of CABG procedures represents a strong predictor of an AO after surgery. Analyzing blood samples for cTnI with an automated device on site in the OR provides for immediate results, so specific diagnostic and therapeutic interventions can be performed before hemodynamics deteriorate.

Aortocoronary bypass grafting: a comparison of HTK cardioplegia vs. intermittent aortic cross-clamping

OBJECTIVE

Intermittend, hypothermic aortic cross-clamping (IAC) with myocardial fibrillation and cardioplegic arrest (CA) have been established both as effective methods for coronary artery bypass surgery (CABG). Nevertheless, there exists controversy about the more beneficial cardioprotective effect of one of these procedures in CABG-patients.

METHODS

In this prospective study we compared the clinical outcome, ischemic serum-markers (CK, CK-MB, Troponin I), electrocardiogram (ECG)-changes, and hemodynamic data of 103 patients. Randomization in group I (IAC; n=52) or group II (CA; n=51) was done consecutively, all data were compared by Student's t-test or chi(2)-test and P<0.05 was regarded as significant. The Bretschneider-HTK solution was used for cardioplegic arrest. Data were collected before operation, before ischemic arrest, after 5 and 60 min of reperfusion, 1 and 6 h after operation, 1, 2 and 10 days postoperatively.

RESULTS

There were no significant differences between both groups regarding general patient data: age (IAC: 64. 8+/-9.2 vs. CA: 63.8+/-9.0 years), left ventricular function (ejection fraction: IAC: 62+/-14 vs. CA: 64+/-13%), the amount of bypassed vessels (IAC: 3.4+/-0.5 vs. CA: 3.6+/-0.5), total bypass time (IAC: 113+/-31 vs. CA 108+/-20 min). The total time of ischemia was significantly less in the IAC group with 37+/-10 vs. 48+/-10 min in the CA group. In the IAC-group, a higher mortality was noticed (7. 7 vs. 3.9%; N.S.). This was combined with a significantly higher amount of patients with peak serum-values of CK-MB (>40 U/l) and troponin I (>50 ng/ml), 17 in the IAC-group (33%) vs. eight in CA-group (16%). Cerebral strokes were seen in two IAC-patients and none in CA-patients (NS). ECG-changes occurred in 22 IAC patients (42%) vs. 16 CA patients (31%); persistent ischemia related ECG-changes in six IAC (11.5%) vs. five CA-patients (9.8%).

CONCLUSIONS

Both cardioprotective methods, IAC and HTK-cardioplegia, seem to offer sufficient myocardial protection in normal CABG-procedures. Although neurologic disorders and mortality rates were higher in patients with intermittent aortic cross-clamping, the differences to the cardioplegia group were not significant. According to the analysis of increased ECG-changes, higher CK-MB and troponin I values, which occurred especially in patients with myocardial ischemia time longer than 40 min, we conclude that cardioplegic arrest with HTK seems to offer more beneficial effects in procedures with prolonged ischemia.

Release of cardiac troponin I in antegrade crystalloid versus cold blood cardioplegia

OBJECTIVE

The purpose of this study was to assess the efficacy of myocardial protection, comparing antegrade crystalloid cardioplegia with cold blood cardioplegia, in patients with preserved left ventricular function who were undergoing elective first coronary artery bypass grafting. Release of cardiac troponin I was used as a marker for the effectiveness of myocardial protection.

METHODS

A consecutive series of 62 patients were randomly assigned to receive crystalloid or blood cardioplegia. Cardiac troponin I concentrations were determined in venous blood samples before the operation, immediately after unclamping, at 6, 9, 12, and 24 hours, and daily thereafter for 5 days.

RESULTS

Rising levels of troponin I were found in all patients. The time course and peak release were similar in the crystalloid cardioplegia and the blood cardioplegia groups. No patients in either group had electrocardiographic evidence of perioperative myocardial infarction. Cardiac troponin I was able to detect small areas of myocardial damage, not revealed by electrocardiography or creatine kinase MB release. Aprotinin administration was associated with lower cardiac troponin I release in both groups. Cardiac troponin I was lower in patients whose conditions did not require electrical defibrillation after aortic unclamping, irrespective of cardioplegia type. The presence of a main stem lesion was associated with higher cardiac troponin I release only in the crystalloid cardioplegia group.

CONCLUSIONS

Antegrade cold blood cardioplegia is equally effective as antegrade crystalloid cardioplegia in a randomized group of patients with preserved left ventricular function who were undergoing elective first coronary artery bypass grafting. Aprotinin administration resulted in lower cardiac troponin I release, whereas electrical defibrillation was related to a higher release irrespective of cardioplegia type. The presence of a main stem lesion resulted in higher cardiac troponin I release in the crystalloid cardioplegia group.

Short periods of regional ischaemia and reperfusion provoke release of troponin I from the human hearts

Whether cardiac troponin I (cTnI) is better at detecting minor myocardial damage than other biochemical markers, is still controversial. In this report we monitored the response of the human heart to short periods of regional ischaemia and reperfusion (3 min each) by measuring cTnI release in the coronary sinus and the radial artery of patients undergoing coronary revascularisation surgery on beating heart without cardiopulmonary bypass. Our data show for the first time that the human heart releases significant amounts of cTnI in response to minor cardiac insults. However because of dilution, this release cannot be easily detected outside the coronary circulation. Therefore, an improved sensitivity of the assays used to measure cTnI may provide an ideal tool for assessing minor myocardial damage.

Intraoperative cardiac troponin T release and lactate metabolism during coronary artery surgery: comparison of beating heart with conventional coronary artery surgery with cardiopulmonary bypass

OBJECTIVE

To compare cardiac troponin T release and lactate metabolism in coronary sinus and arterial blood during uncomplicated coronary grafting on the beating heart with conventional coronary grafting using cardiopulmonary bypass.

DESIGN

A prospective observational study with simultaneous sampling of coronary sinus and arterial blood: before and 1, 4, 10, and 20 minutes after reperfusion for analysis of cardiac troponin T and lactate. Cardiac troponin T was also analysed in venous samples taken 3, 6, 24, 48, and 72 hours after surgery.

SETTING

Cardiac surgical unit in a tertiary referral centre.

PATIENTS

18 patients undergoing coronary grafting on the beating heart (10 single vessel and eight two-vessel grafting) and eight undergoing two-vessel grafting with cardiopulmonary bypass.

RESULTS

Cardiac troponin T was detected in coronary sinus blood in all patients by 20 minutes after beating heart coronary artery surgery before arterial concentrations were consistently increased. Peak arterial and coronary sinus cardiac troponin T values on the beating heart during single (0.03 (0 to 0. 05) and 0.09 (0.07 to 0.16 microg/l, respectively) and two-vessel grafting (0.1 (0.07 to 0.11) and 0.19 (0.14 to 0.25) microg/l) were lower than the values obtained during cardiopulmonary bypass (0.64 (0.52 to 0.72) and 1.4 (0.9 to 2.0) microg/l) (p < 0.05). The area under the curve of venous cardiac troponin T over 72 hours for two-vessel grafting on the beating heart was less than with cardiopulmonary bypass (13 (10 to 16) v 68 (26 to 102) microg.h/l) (p < 0.001). Lactate extraction began within one minute of snare release during beating heart coronary surgery while lactate was still being produced 20 minutes after cross clamp release following cardiopulmonary bypass.

CONCLUSIONS

Lower intraoperative and serial venous cardiac troponin T concentrations suggest a lesser degree of myocyte injury during beating heart coronary artery surgery than during cardiopulmonary bypass. Oxidative metabolism also recovers more rapidly with beating heart coronary artery surgery than with conventional coronary grafting. Coronary sinus cardiac troponin T concentrations increased earlier and were greater than arterial concentrations during beating heart surgery, suggesting that this may be a more sensitive method of intraoperative assessment of myocardial injury.

A clinical comparative study between crystalloid and blood-based St Thomas' hospital cardioplegic solution

OBJECTIVE

Myocardial protection with blood cardioplegia during cardiac surgery is increasingly preferred, but few studies have compared the protective effects of crystalloid cardioplegia to the same solution with blood as the only variable. This clinical study compared the protective effects of crystalloid or blood-based St. Thomas' Hospital cardioplegic solution No. 1.

METHODS

Fifty higher risk patients undergoing elective coronary artery bypass surgery, with an ejection fraction less than 40%, were randomly allocated to receive cold (4 degrees C) intermittent crystalloid St. Thomas' No. 1 cardioplegia (n = 25), or a similar blood-based solution (n = 25) with a haematocrit of 10-12%. We determined (1) peri-operative and post-operative arrhythmias, (2) left and right ventricular function (24 h) using the thermodilution technique, (3) left ventricular high-energy phosphate content sampled before ischaemia, the end of ischaemia and the end of bypass.

RESULTS

Pre-operative haemodynamic data, aortic cross-clamp and bypass times were similar in both groups of patients; there was no mortality. At the end of ischaemia there were no differences in ATP content between groups but creatine phosphate was maintained at a significantly (P < 0.007) higher level in the blood-based St. Thomas' cardioplegia group than the crystalloid St. Thomas' cardioplegia group (20+/-2 (SE) vs. 13+/-1 micromol/g dry wt, respectively). Return to spontaneous sinus rhythm was significantly (P = 0.002) increased in the blood-based St. Thomas' cardioplegia group (96%) compared to the crystalloid St. Thomas' cardioplegia group (60%). Early post-operative ventricular dysfunction occurred in both groups, but normal LV function (stroke work index) recovered significantly (P = 0.043) more rapidly (by 2 h) in the blood-based St. Thomas' cardioplegia group of patients.

CONCLUSIONS

In a higher risk (EF < 40%) group of patients undergoing elective cardiac surgery, addition of blood to an established crystalloid cardioplegic solution significantly enhanced myocardial protection by reducing arrhythmias, improving rate of recovery of function and maintaining myocardial high-energy phosphate content during ischaemia.