Does cardioplegia type affect outcome and survival in patients with advanced left ventricular dysfunction? Results from the CABG Patch Trial

Del Nido vs. Cold Blood Cardioplegia for High-Risk Isolated Coronary Artery Bypass Grafting in Patients with Reduced Ventricular Function

INTRODUCTION

The evidence for using del Nido cardioplegia protocol in high-risk patients with reduced ejection fraction undergoing isolated coronary surgery is insufficient.

METHODS

The institutional database was searched for isolated coronary bypass procedures. Patients with ejection fraction < 40% were selected. Propensity matching (age, sex, infarction, number of grafts) was used to pair del Nido (Group 1) and cold blood (Group 2) cardioplegia patients. Investigation of biomarker release, changes in ejection fraction, mortality, stroke, perioperative myocardial infarction, composite endpoint (major adverse cardiac and cerebrovascular events), and other perioperative parameters was performed.

RESULTS

Matching allowed the selection of 45 patient pairs. No differences were noted at baseline. After cross-clamp release, spontaneous sinus rhythm return was observed more frequently in Group 1 (80% vs. 48.9%; P=0.003). Troponin values were similar in both groups 12 and 36 hours after surgery, as well as creatine kinase at 12 hours. A trend favored Group 1 in creatine kinase release at 36 hours (median 4.9; interquartile range 3.8-9.6 ng/mL vs. 7.3; 4.5-17.5 ng/mL; P=0.085). Perioperative mortality, rates of myocardial infarction, stroke, or major adverse cardiac and cerebrovascular events were similar. No difference in postoperative ejection fraction was noted (median 35.0%; interquartile range 32.0-38.0% vs. 35.0%; 32.0-40.0%; P=0.381). There was a trend for lower atrial fibrillation rate in Group 1 (6.7% vs. 17.8%; P=0.051).

CONCLUSION

The findings indicate that del Nido cardioplegia provides satisfactory protection in patients with reduced ejection fraction undergoing coronary bypass surgery. Further prospective trials are required.

Surgical results of only antegrade del Nido cardioplegia infusion in conventional coronary artery bypass grafting: a retrospective study

BACKGROUND

Additional retrograde cardioplegia infusion in conventional coronary artery bypass grafting (CABG) was introduced to address the concern of inappropriate cardioplegia delivery through the stenotic coronary artery. However, this method is complex and requires repeated infusions. Therefore, we investigated the surgical outcomes of only antegrade cardioplegia infusion in conventional CABG.

METHODS

We included 224 patients who underwent isolated CABG between 2017 and 2019. The patients were divided into two groups according to the cardioplegia infusion method: antegrade cardioplegia infusion with del Nido solution (n=111, group I) and antegrade+retrograde cardioplegia infusion with blood cardioplegia solution (n=113, group II).

RESULTS

The sinus recovery time after release of the aorta cross-clamp was shorter in group I (3.8±7.1 minutes, n=98) than in group II (5.8±4.1 minutes, n=73) (p=0.033). The total cardioplegia infusion volume was lower in group I (1,998.6±668.6 mL) than in group II (7,321.0±2,865.3 mL) (p<0.001). Creatine kinase-MB levels were significantly lower in group I than in group II (p=0.039). Newly developed regional wall motion abnormalities on follow-up echocardiography were detected in two patients (1.8%) in group I and five patients (4.4%) in group II (p=0.233). There was no significant difference in ejection fraction improvement between the two groups (3.3%±9.3% in group I and 3.3%±8.7% in group II, p=0.990).

CONCLUSION

The only antegrade cardioplegia infusion strategy in conventional CABG is safe and has no harmful effects.

On-pump beating heart versus off-pump myocardial revascularization-a propensity-matched comparison

Objective

On-pump beating heart (OP-BH) coronary artery bypass grafting (CABG) is often undertaken as an alternative between off-pump coronary artery bypass (OPCAB) and conventional on-pump coronary artery bypass grafting (On-pump CABG), especially in India. However, outcome data following OP-BH surgery is sparse. The aim of this study was to compare the outcomes of OP-BH CABG with OPCAB.

Methods

From our institutional database, all patients undergoing OP-BH CABG (n = 531) were identified. A propensity-matched cohort undergoing OPCAB (n = 531) was identified from the database. Nearest neighbor matching technique was used and the groups were matched for variables including age, gender, body mass index, EuroSCORE, history of recent myocardial infarction or unstable angina, hypertension, peripheral vascular disease, chronic obstructive airway disease, diabetes, pre-op renal impairment, pre-op neurological events, and left ventricular function.

Results

The propensity-matched groups were well matched in terms of baseline characteristics. The mean EuroSCORE was 3.17 and 3.20 in the OP-BH and the OPCAB groups. The unadjusted 30-day mortality in the propensity-matched OPCAB group was 2.07% (11/531) while mortality in the on-pump beating heart group was significantly higher at 6.9% (37/531). Multivariate analysis showed that OP-BH CABG was an independent risk factor for 30-day mortality as well as major adverse post-operative outcomes including renal, neurological, and respiratory outcomes and post-operative atrial fibrillation.

Conclusions

OP-BH CABG is associated with worse clinical outcomes compared to patients undergoing OPCAB.

Warm Blood Cardioplegia for Myocardial Protection: Concepts and Controversies

Warm blood cardioplegia has been an established cardioplegic method since the 1990s, yet it remains controversial in regard to myocardial protection. This review will describe the physiologic and technical concepts behind warm blood cardioplegia, as well as outline the current basic and clinical research that evaluates its usefulness. Controversies regarding this technique will also be reviewed. A long history of experimental data indicates that warm blood cardioplegia is safe and effective and thus suitable myocardial protection during cardiopulmonary bypass surgeries.

Application of strain and other echocardiographic parameters in the evaluation of early and long-term clinical outcomes after cardiac surgery revascularization

Background

Coronary artery bypass graft (CABG) surgery is an effective therapeutic strategy for coronary heart disease (CHD). Myocardial longitudinal strain echocardiography with 2D speckle tracking could obtain ventricular function with better accuracy and reliability than the left ventricular ejection fraction.

The aim of the study was to assess changes in left ventricular function in patients before and after surgical revascularization for a 24-month period of observation, using echocardiography with speckle tracking strain imaging. We searched for echocardiographic predictors of poor early and long-term outcome after CABG.

Methods

We enrolled 69 patients scheduled for elective coronary bypass grafting. Patients were divided into groups based on pre-operative systolic and diastolic parameters, depending on the GLS value and the E’ Lat and E/E’ value. The correlation between these parameters and early and long-term outcomes was analyzed.

Results

Preoperative EF was preserved in 86, 95% (60) patients. Pre-operative reduced GLS was observed in 73.91% (51) of patients and severely reduced in 31.88% (22).

In the first post-operative 6-month period, we observed a significant decrease in the GLS. The GLS was a predictor of early postoperative outcome for intubation time, the inotropes use and length of ICU stay. Diastolic dysfunction was a predictor of the greater inotrope requirements.

Conclusions

Global longitudinal strain and diastolic dysfunction parameters are a good predictors of worse early outcome after CABG.

CABG in patients with left ventricular dysfunction: indications, techniques and outcomes

Ischemic chronic heart failure (CHF) represents one of the cardiovascular diseases with the worst degree of morbidity and mortality in the western world, and with the highest health care costs. Despite several studies demonstrated that surgical revascularization (CABG), especially in the presence of viable myocardium, improve heart function, and therefore, survival, the matter remains unclear and controversial. In the late 1970s, the Coronary Artery Surgery Study showed that a subgroup of patients with coronary artery disease, angina, and reduce LV function had a significant survival benefit after CABG compared to those treated medically. The key concept behind this observation was the presence of viable myocardium, which can resume function following revascularization. In contrary, the surgical treatment for ischemic heart failure (STICH) trial, which randomized patients with CAD and LV dysfunction to evidence-based medical therapy or CABG plus medical therapy, failed to demonstrate at a median follow-up of 56 months a significant difference between the CABG group and the medical therapy group in the rate of death from any cause. However, the results of the STICH extension study (STICHES) at 10 years follow-up demonstrated that CABG is associated with a significant reduction in all-cause mortality, cardiovascular mortality, and readmission for heart compared to optimal medical therapy (OMT) in patients with severe ischemic LV dysfunction. Therefore, this review discusses the available evidences in literature, from observational studies to randomized trials, including operative techniques and controversial issues, in order to better clarify the role of CABG in the current management of ischemic patients with LVD.

Blood cardioplegia benefits only patients with a long cross-clamp time

INTRODUCTION

A clear advantage of blood versus crystalloid cardioplegia has not yet been observed in smaller population studies. The purpose of this article was to further investigate the clinical outcomes of blood versus crystalloid cardioplegia in a large propensity-matched cohort of patients who underwent cardiac surgery.

METHODS

The study was a single-centre study. Data was withdrawn from the Western Denmark Heart Registry, which comprises a perfusion section for each procedure. A total of 4,852 patients were propensity matched into crystalloid (CC) vs blood cardioplegia (BC) groups. The primary end points were creatinine kinase-MB (CKMB) elevation, acute myocardial infarction (AMI), stroke, dialysis, coronary angiography (CAG) and mortality (30 days and 6 months).

RESULTS

We found lower odds ratio in 30-day mortality in the BC group (OR 0.21; CI 0.06-0.68), but no difference in overall 6-month mortality. There was no difference in CKMB elevation, AMI, dialysis or stroke. Several end points were further analysed for different cross-clamp times. In the CC group, ventilation time above 600 minutes was seen more often in almost all cross-clamp time intervals (23.5 % vs 12.2 %; p<0.0001; χ²-test) and 6-month mortality was significantly higher when the cross-clamp time exceeded 210 minutes (64.3 vs 23.8; p=0.018; χ²-test).

CONCLUSIONS

We did not find clear evidence of superiority of either type in the uncomplicated patient. When prolonged cross-clamp time or postoperative ventilation is expected, this study indicates that blood cardioplegia might be preferable.

Warm blood cardioplegia versus cold crystalloid cardioplegia for myocardial protection during coronary artery bypass grafting surgery

We retrospectively analyzed early results of coronary artery bypass grafting (CABG) surgery using two different types of cardioplegia for myocardial protection: antegrade intermittent warm blood or cold crystalloid cardioplegia. From January 2015 to October 2016, 330 consecutive patients underwent isolated on-pump CABG. Cardiac arrest was obtained with use of warm blood cardioplegia (WBC group, n = 297) or cold crystalloid cardioplegia (CCC group, n = 33), according to the choice of the surgeon. Euroscore II and preoperative characteristics were similar in both groups, except for the creatinine clearance, slightly lower in WBC group (77.33 ± 27.86 mL/min versus 88.77 ± 51.02 mL/min) (P < 0.05). Complete revascularization was achieved in both groups. In-hospital mortality was 2.0% (n = 6) in WBC group, absent in CCC group. The required mean number of cardioplegia’s doses per patient was higher in WBC group (2.3 ± 0.8) versus CCC group (2.0 ± 0.7) (P = 0.045), despite a lower number of distal coronary artery anastomoses (2.7 ± 0.8 versus 3.2 ± 0.9) (P = 0.0001). Cardiopulmonary and aortic cross-clamp times were similar in both groups. The incidence of perioperative myocardial infarction (WBC group 3.4% versus CCC group 3.0%) and low cardiac output syndrome (4.4% versus 3.0%) were similar in both groups. As compared with WBC group, in CCC group CK-MB/CK ratio >10% was lower during each time points of evaluation, with a statistical significant difference at time 0 (4% ± 1.6% versus 5% ± 2.5%) (P = 0.021). In presence of complete revascularization, despite the value of CK-MB/CK ratio >10% was less in the CCC group, clinical results were not affected by both types of cardioplegia adopted to myocardial protection. As compared with cold crystalloid, warm blood cardioplegia requires a shorter interval of administration to achieve better myocardial protection.

Is cold blood cardioplegia absolutely superior to cold crystalloid cardioplegia in aortic valve surgery?

BACKGROUND

Experimental evidence suggests that blood cardioplegia (BCP) may be superior to cold crystalloid cardioplegia (CCP) for myocardial protection. However, robust clinical data are lacking. We compared postoperative outcome of patients undergoing aortic valve replacement (AVR) using cold anterograde-retrograde intermittent BCP versus anterograde (CCP).

METHODS

Adult consecutive isolated AVR performed between April 2006 and February 2011 at the Royal Infirmary Hospital of Edinburgh were retrospectively analyzed. The use of anterograde CCP was compared with that of intermittent anterograde-retrograde cold BCP. End points were intra-operative mortality, 30-day hospital re-admission, need for RBC or platelet transfusion, mechanical ventilation time and renal failure.

RESULTS

Of total 774 cases analyzed, 592 cases of BCP and 182 cases of CCP were identified. Demographics did not differ between groups (mean age: 67±12 years in CCP and 69±12 years in BCP). Groups (BCP vs. CCP) were indistinguishable (P>0.05, not significant) based on: average aortic cross clamp time 77.01±14.47 vs. 75.78±18.78 minutes, cardiopulmonary bypass time 104.07±43.70 vs. 100.34±25.90 minutes, surgery time 190.53±61.80 vs. 204.04±51.09 minutes and postoperative total blood consumption 1.38±2.11 vs. 1.61±2.4 units. The percentage of patients who required platelets' transfusion was similar: 12.8% BCP and 18.7% CCP (Fisher's exact test, P=0.053). Prevalence of respiratory failure was lower in BCP than in CCP: 2.6% vs. 6.3% (P=0.028). Admission time (days) at ICU was 3.63± 21.90 in BCP and 3.07±8.04 in CCP (not significant). Intra-hospital mortality, 30-day hospital re-admission, renal failure, sepsis, wound healing and stroke did not differ between groups.

CONCLUSIONS

BCP was strictly not superior to CCP in every aspect. In particular it was definitely not superior in terms of postoperative ventricular function. Our results question the absolute superiority of BCP over CCP in terms of hard outcomes. Likelihood of serious complications should be considered to improve risk profile of patients before choosing a cardioplegic solution.

Coronary Sinus Lactate as Marker of Myocardial Ischemia in Cardiac Surgery: Correlation with Morbidity and Mortality after Cardiac Surgery / Lactatul din sinusul coronarian - marker al ischemiei miocardice în chirurgia cardiacă: corelaţii cu morbiditatea şi mortalitatea postoperatorie

Introduction. Perioperative myocardial injuries are one of the most frequent causes of morbidity and mortality after cardiac surgery, the most common etiology being the poor myocardial protection during aortic crossclamp. During aortic crossclamp progressive accumulation of lactate and intracellular acidosis are well-known phenomena, and are associated with alteration of myocardial contractile function. Our objective was to study the coronary sinus lactate levels as a predictor of postoperative hemodynamic outcome in open-heart surgical patients.

Material and methods. We performed a prospective clinical trial, including 142 adult patients with elective cardiac surgery. Anterograde cardioplegia was administered in 82 patients, retrograde cardioplegia in 60 (in 30 patients it was administrated intermittently and in 30 continuously). Blood was collected simultaneously from the aortic cardioplegic line (inflow) and from coronary sinus or the aortic root (outflow) before aortic crossclamp, after crossclamp at every 10 minutes and after crossclamp removal at 0 and 10 minutes. All patients were operated on cardiopulmonary bypass with cardiac arrest, using warm-blood cardioplegia for cardioprotection.

Results. Lactate levels showed increasing values during aortic crossclamp, and a rapid decline after crossclamp removal. The incidence of low cardiac output was significantly higher in patients with lactate levels that exceeded 4 mmol/L. In patients who died in the postoperative period, lactate level was even higher (5 mmol/L), with only a modest recovery after crossclamp removal.

Conclusion. Monitoring lactate level in coronary sinus blood is a reliable method and has a good prognostic value regarding postoperative morbidity and mortality in open heart surgery

Myocardial protection and early outcome of different coronary surgical techniques for diabetic patients with triple vessels

BACKGROUND AND OBJECTIVES

For patients with diabetes and triple-vessel disease, coronary artery bypass grafting (CABG) surgery is a well-established procedure, but cardiopulmonary bypass support may also lead to severe complications to these patients. The aim of this study was to compare myocardial protection and early outcomes in patients with diabetes and triple-vessel disease following different coronary surgical techniques.

DESIGN AND SETTINGS

Prospective randomized trial of patients treated at the First Affiliated Hospital of China Medical University over a 3-year period (2011- 2013).

METHODS

In a single-center randomized trial, 668 patients with diabetes and triple-vessel disease were randomly assigned to off-pump (OPCAB) (number [n]=222), on-pump beating heart (OnP-BH) (n=223), and conventional CABG (OnP) (n=223) between January 2011 and October 2013. Myocardial injury was assessed by measuring the serial release of cardiac troponin I (cTnI) preoperatively, 1 hour, 12 hours, 24 hours, and 72 hours postoperatively. The early outcomes were compared among these 3 groups.

RESULTS

Preoperative characteristics of the patients in all 3 groups were similar. No significant difference was found regarding the number of anastomoses, the use of the internal thoracic artery, postoperative new-onset atrial fibrillation, hemodialysis, stroke, reoperation for bleeding, and infective complications in the 3 groups (P > .05). The complete revascularization, postoperative drainage loss, intra-aortic balloon pump support, blood requirements, postoperative myocardial infarction, pulmonary complications, gastrointestinal complications, inotropic requirements > 24 hours, ventilation > 24 hours, intensive care unit stay > 24 hours, and in-hospital stay > 7 days were significantly lower in the OPCAB group than in the other 2 groups (P < .05). In-hospital mortality was lower in the OPCAB group than in the other 2 groups, but no statistical difference was observed (P > .05). Preoperative cTnI in the 3 groups was similar (P > .05); however, the lowest cTnI value was noted in the OPCAB group, followed by the OnP group, and it was highest in the OnP-BH group 1 hour, 12 hours, 24 hours, and 72 hours postoperatively (P < .05).

CONCLUSION

OPCAB is superior to the OnP-BH and OnP techniques in terms of postoperative complications and myocardial protection in patients with diabetes and triple-vessel disease. Myocardial injury in the OnP-BH group was significantly higher than that in the OnP group.

Adjuvant cardioprotection in cardiac surgery: update

Cardiac surgery patients are now more risky in terms of age, comorbidities, and the need for complex procedures. It brings about reperfusion injury, which leads to dysfunction and/or loss of part of the myocardium. These groups of patients have a higher incidence of postoperative complications and mortality. One way of augmenting intraoperative myocardial protection is the phenomenon of myocardial conditioning, elicited with brief nonlethal episodes of ischaemia-reperfusion. In addition, drugs are being tested that mimic ischaemic conditioning. Such cardioprotective techniques are mainly focused on reperfusion injury, a complex response of the organism to the restoration of coronary blood flow in ischaemic tissue, which can lead to cell death. Extensive research over the last three decades has revealed the basic mechanisms of reperfusion injury and myocardial conditioning, suggesting its therapeutic potential. But despite the enormous efforts that have been expended in preclinical studies, almost all cardioprotective therapies have failed in the third phase of clinical trials. One reason is that evolutionary young cellular mechanisms of protection against oxygen handling are not very robust. Ischaemic conditioning, which is among these, is also limited by this. At present, the prevailing belief is that such options of treatment exist, but their full employment will not occur until subquestions and methodological issues with the transfer into clinical practice have been resolved.

Analysis of myocardial temperature changes in conventional isolated coronary artery bypass grafting

Backgrounds

To determine whether cold blood cardioplegia (CBCP) can get over coronary artery lesions, we analyzed the relationship between myocardial temperature changes and lesion severity of major coronary arteries.

Methods and results

From April 1991 to October 2003, we measured myocardial temperature before and after antegrade and retrograde delivery of CBCP in 492 patients undergoing conventional coronary artery bypass grafting. Stenotic severity of three major coronary arteries was classified into four grades according to preoperative coronary arteriography; grade 0 for 50 % or less, 1 for 75 %, 2 for 90 %, 3 for 99 % or 100 %. We analyzed relationships between myocardial temperature changes [ΔT-A (antegrade) & ΔT-R (retrograde)] and the coronary artery lesion’s severity. Average ΔT-A of the right coronary artery had no relationship with stenotic grades. Mean ΔT-A of the left anterior descending (LAD) became less and less in proportion to its stenotic grade [9.7 °C for grade 0, 8.2 °C for grade 1, 7.1 °C for grade 2, and 6.0 °C for grade 3, respectively, (p = 0.0042)]. ΔT-A of the circumflex artery showed similar but weaker tendency than those of LAD. Significant inverse correlations were found between ΔT-A and ΔT-R1 in each territory (p < 0.001).

Conclusions

Antegrade delivery was less effective in situations with tight proximal lesion, especially in the LAD territory. Retrograde delivery supplemented antegrade delivery. Myocardial temperature monitoring enables us to deal with inadequate cardioplegic delivery, and is a good indicator of myocardial protection.

Hyperkalemic cardioplegia for adult and pediatric surgery: end of an era?

Despite surgical proficiency and innovation driving low mortality rates in cardiac surgery, the disease severity, comorbidity rate, and operative procedural difficulty have increased. Today's cardiac surgery patient is older, has a "sicker" heart and often presents with multiple comorbidities; a scenario that was relatively rare 20 years ago. The global challenge has been to find new ways to make surgery safer for the patient and more predictable for the surgeon. A confounding factor that may influence clinical outcome is high K(+) cardioplegia. For over 40 years, potassium depolarization has been linked to transmembrane ionic imbalances, arrhythmias and conduction disturbances, vasoconstriction, coronary spasm, contractile stunning, and low output syndrome. Other than inducing rapid electrochemical arrest, high K(+) cardioplegia offers little or no inherent protection to adult or pediatric patients. This review provides a brief history of high K(+) cardioplegia, five areas of increasing concern with prolonged membrane K(+) depolarization, and the basic science and clinical data underpinning a new normokalemic, "polarizing" cardioplegia comprising adenosine and lidocaine (AL) with magnesium (Mg(2+)) (ALM™). We argue that improved cardioprotection, better outcomes, faster recoveries and lower healthcare costs are achievable and, despite the early predictions from the stent industry and cardiology, the "cath lab" may not be the place where the new wave of high-risk morbid patients are best served.

Is cold or warm blood cardioplegia superior for myocardial protection?

A best evidence topic in cardiac surgery was written according to a structured protocol. The question addressed was whether the use of warm or cold blood cardioplegia has superior myocardial protection. More than 192 papers were found using the reported search, of which 20 represented the best evidence to answer the clinical question. The authors, journal, date, country of publication, patient group studied, study type, relevant outcomes and results of these papers are tabulated. A good breadth of high-level evidence addressing this clinical dilemma is available, including a recent meta-analysis and multiple large randomized clinical trials. Yet despite this level of evidence, no clear significant clinical benefit has been demonstrated by warm or cold blood cardioplegia. This suggests that neither method is significantly superior and that both provide similar efficacy of myocardial protection. The meta-analysis, including 41 randomized control trials (5879 patients in total), concluded that although a lower cardiac enzyme release and improved postoperative cardiac index was demonstrated in the warm cardioplegia group, this benefit was not reflected in clinical outcomes, which were similar in both groups. This theme of benefit in biochemical markers, physiological metrics and non-fatal postoperative events in the warm cardioplegia group ran throughout the literature, in particular the 'Warm Heart investigators' who conducted a randomized trial of 1732 patients, demonstrated a reduction in postoperative low output syndrome (6.1 versus 9.3%, P = 0.01) in the warm cardioplegia group, but no significant drop in 30-day all-cause mortality (1.4 versus 2.5%, P = 0.12). However, their later follow-up indicates non-fatal postoperative events predict reduced late survival, independent of cardioplegia. A minority of studies suggested a benefit of cold cardioplegia over warm in particular patient subgroups: One group conducted a retrospective study of 520 patients who required prolonged aortic cross-clamp times, results demonstrated less myocardial damage and reduced postoperative cardiac mortality and morbidity in the cold group. The clinical bottom line is that warm and cold cardioplegia result in similar short-term mortality. However, large studies have shown that warm cardioplegia reduces adverse post-operative events; the significance of which is unclear.

Effect of duration of ischemia on myocardial proteome in ischemia/reperfusion injury

Ischemia/reperfusion (I/R) injury is a serious problem resulting from clinical setting of coronary revascularization. Despite extensive studies on I/R injury, the molecular bases of cardiac dysfunction caused by I/R are still unknown, but are likely to result from alterations in protein expression. Isolated rat hearts were subjected to 15-30 min of no-flow ischemia without (Ischemia protocol) or with 30 min of reperfusion (I/R protocol). 2-DE analysis of heart proteins from both experimental protocols showed wide-ranging changes in protein levels. In the Ischemia protocol, 39 protein spots were changed in ischemic groups and those changes correlated with duration of ischemia. Ninety percent of the affected proteins were increased. In contrast to increased protein levels, the total messenger RNA (mRNA) level decreased approximately two fold. Compared to the Ischemia protocol, changes in protein levels in the I/R protocol did not correlate with the duration of ischemia and the degree of recovery of mechanical function. The decrease of affected protein from I/R protocol was associated with the increase in total protein level in reperfusate. Our studies show that the protein increase is correlated with the mechanical function of the I/R hearts and the increase is not likely associated with an increase in protein synthesis.

Warm nondepolarizing adenosine and lidocaine cardioplegia: Continuous versus intermittent delivery

OBJECTIVE

Continuous infusion of warm to normothermic cardioplegia may limit the surgeon's visual field, increase coronary vascular resistance, and lead to potassium-exacerbated ischemia-reperfusion damage. Our aim was to examine the versatility of a new normokalemic, nondepolarizing adenosine-lidocaine cardioplegia during continuous or intermittent infusion at 33 degrees C and compare it with lidocaine cardioplegia.

METHODS

Isolated, perfused rat hearts (n = 6 each group) were arrested at 33 degrees C for 40 or 60 minutes with 200 microm of adenosine and 500 microm of lidocaine in Krebs-Henseleit buffer (10 mmol/L glucose, pH 7.6-7.7 at 37 degrees C) or 500 microm of lidocaine in Krebs-Henseleit buffer for 60 minutes delivered at 60 mm Hg.

RESULTS

Times to arrest were 7 to 10 seconds for the adenosine-lidocaine groups and 102 seconds for the lidocaine group (P < .05). Total cardioplegia volumes for intermittent (2 minutes every 18 minutes) and continuous deliveries were 122 to 159 mL and 699 to 922 mL for the 40- and 60-minute adenosine-lidocaine arrest protocols, respectively, and 136 mL for the 60-minute intermittent lidocaine group. In the last 2 minutes of the 40- and 60-minute arrest protocols, the coronary vascular resistance was not significantly different for the hearts arrested with adenosine and lidocaine (0.27-0.32 megadyne/sec/cm(-5)). Significantly higher coronary vascular resistance was found in the lidocaine cardioplegia group (0.38 megadyne/sec/cm(-5)). No significant differences were found between the continuous or intermittent adenosine-lidocaine delivery protocols. Hearts arrested with adenosine and lidocaine recovered 88% to 89% of aortic flow and 109% of coronary flow at 60 minutes of reperfusion after 40-minute arrest, and 77% to 86% of aortic flow and 98% to 109% of coronary flow at 60 minutes of reperfusion after 60-minute arrest. Lidocaine cardioplegia led to significantly lower aortic and coronary flows after 60-minute arrest compared with the intermittent adenosine-lidocaine group.

CONCLUSIONS

We conclude that adenosine-lidocaine cardioplegia can be delivered intermittently or continuously with similar functional recoveries after a 40- or 60-minute arrest at 33 degrees C. Hearts receiving lidocaine cardioplegia took a significantly longer time to arrest, showed higher coronary vascular resistance, and achieved lower functional recovery than the 60-minute adenosine-lidocaine cardioplegia groups. Intermittent or continuous delivery of adenosine-lidocaine cardioplegia may offer an alternative to current surgical hyperkalemic cardioplegia at warm to normothermic temperatures.

Inflammatory and metabolic response of the myocardium during aortic valve surgery on the beating heart

This study has been conducted in an effort to establish metabolic and inflammatory responses of the myocardium during aortic valve surgery on the beating heart with CPB and continuous coronary sinus perfusion with normothermic blood. Twenty patients, divided into two groups, participated in this study. Conventional aortic valvular operations were performed on first 10 patients, while the second group, consisting of 10 patients as well, was subjected to the operations with CPB on the beating heart with continuously perfusion with blood through coronary sinus. There were total of 14 biological and 6 mechanical valves implanted in aortic position. In this study, cardiac markers and inflammatory mediators IL-8 and TNF, were measured preoperatively and postoperatively. Metabolic changes were documented based on the levels of CK-MB, troponin I, myoglobin and LDH. Inflammatory factors we measured through IL-8 and TNF. All measurements were taken in 6 hour intervals during the initial 48 hours following the operations. The patients of "the beating heart" group had significantly lower dose of markers and cytokines in comparison to those who had undergone the conventional valvular operation. The elimination of the adverse effects of global ischemia produced from reperfusion injury and the similarity to the physiological condition, suggests that the revival of the beating heart procedure is more reasonable. This procedure of valvular surgery on the beating heart can be one of the good surgical options for the high-risk valvular patients.

Cold crystalloid cardioplegia

Cold crystalloid cardioplegia is clinically used since the mid-1960s. It is currently applied in adult and pediatric cardiac surgery patients and remains the preferred method of myocardial protection for many cardiac surgeons. This chapter gives a brief overview about the technical aspects of cold crystalloid cardioplegia application in the operating room.

Hemodynamic management of patients in the first 24 hours after cardiac surgery

OBJECTIVE

To describe the physiologic alterations, evaluation, and hemodynamic management of patients in the first 24 hrs after cardiac surgery.

DESIGN

A brief review of preoperative and intraoperative events, postoperative physiology, and a discussion of the evaluation and hemodynamic management of cardiac surgery patients postoperatively based on a review of the literature, known physiology, and clinical experience.

RESULTS

After cardiac surgery, patients undergo alterations in cardiac performance related to co-morbid conditions, preoperative myocardial insults and interventions, the surgical procedure, and intraoperative management. Predictable responses evolve rapidly in the first 24 hrs after surgery. Monitoring, diagnostic regimens, and therapeutic regimens exist to address the patterns of response and occasional complications.

CONCLUSION

By understanding preoperative and intraoperative events and their evolution in the intensive care unit, clinicians can effectively manage patients who experience cardiac surgery.

Organ arrest, protection and preservation: natural hibernation to cardiac surgery

Cardiac surgery continues to be limited by an inability to achieve complete myocardial protection from ischemia-reperfusion injury. This paper considers the following questions: (1) what lessons can be learned from mammalian hibernators to improve current methods of human myocardial arrest, protection and preservation? and (2) can the human heart be pharmacologically manipulated during acute global ischemia to act more like the heart of a hibernating mammal? After reviewing the major entropy-slowing strategies of hibernation, a major player identified in the armortarium is maintenance of the membrane potential. The resting membrane potential of the hibernator's heart appears to be maintained close to its pre-torpid state of around -85 mV. In open-heart surgery, 99% of all surgical heart arrest solutions (cardioplegia) employ high potassium (>16 mM) which depolarises the membrane voltage from -85 to around -50 mV. However, depolarising potassium cardioplegia has been increasingly linked to myocyte and microvascular damage leading to functional loss during reperfusion. Our recent work has been borrowed from hibernation biology and is focused on a very different arrest strategy which 'clamps' the membrane near its resting potential and depresses O2 consumption from baseline by about 90%. The new 'polarising' cardioplegia incorporates adenosine and lidocaine (AL) as the arresting combination, not high potassium. Studies in the isolated rat heart show that AL cardioplegia delivered at 37 degrees C can arrest the heart for up to 4 h with 70-80% recovery of the cardiac output, 85-100% recovery of heart rate, systolic pressure and rate-pressure product and 70-80% of baseline coronary flows. Only 14% of hearts arrested with crystalloid St. Thomas' solution No. 2 cardioplegia survived after 4 h. In conclusion, maintenance of the myocardial membrane potential near or close to its resting state appears to be an important feature of the hibernator's heart that may find great utility in surgical arrest and cellular preservation strategies. Identifying and safely turning 'off' and 'on' the entropy-slowing genes to down-regulate the hibernator's heart and applying this to human organs and tissues remains a major challenge for future genomics and proteomics.

Reduction of myocardial reperfusion injury by aprotinin after regional ischemia and cardioplegic arrest

BACKGROUND

Surgical coronary revascularization with cardiopulmonary bypass and cardioplegia has been associated with reperfusion injury. The serine protease inhibitor aprotinin has been suggested to reduce reperfusion injury, yet a clinically relevant study examining regional ischemia under conditions of cardiopulmonary bypass and cardioplegia has not been performed.

METHODS

Pigs were subjected to 30 minutes of regional myocardial ischemia by distal left anterior descending coronary artery occlusion, followed by 60 minutes of cardiopulmonary bypass with 45 minutes of cardioplegic arrest and 90 minutes of post-cardiopulmonary bypass reperfusion. The treatment group (n = 6) was administered aprotinin systemically (40,000 kallikrein-inhibiting units [KIU]/kg intravenous loading dose, 40,000 KIU/kg pump prime, and 10,000 KIU x kg(-1) x h(-1) intravenous continuous infusion). Control animals (n = 6) received crystalloid solution. Global and regional myocardial functions were analyzed by the left ventricular+dP/dt and the percentage segment shortening, respectively. Left ventricular infarct size was measured by tetrazolium staining. Tissue myeloperoxidase activity was measured. Myocardial sections were immunohistochemically stained for nitrotyrosine. Coronary microvessel function was studied by videomicroscopy.

RESULTS

Myocardial infarct size was decreased with aprotinin treatment (27.0% +/- 3.5% vs 45.3% +/- 3.0%, aprotinin vs control; P <.05). Myocardium from the ischemic territory showed diminished nitrotyrosine staining in aprotinin-treated animals versus controls, and this was significant by grade (1.3 +/- 0.2 vs 3.2 +/- 0.2, aprotinin vs control; P <.01). In the aprotinin group, coronary microvessel relaxation improved most in response to the endothelium-dependent agonist adenosine diphosphate (44.7% +/- 3.2% vs 19.7% +/- 1.7%, aprotinin vs control; P <.01). No significant improvements in myocardial function were observed with aprotinin treatment.

CONCLUSIONS

Aprotinin reduces reperfusion injury after regional ischemia and cardioplegic arrest. Protease inhibition may represent a molecular strategy to prevent postoperative myocardial injury after surgical revascularization with cardiopulmonary bypass.

Hyperkalemic blood versus crystalloid cardioplegia in longer clamping times

The 715 patients who had crystalloid cardioplegia were compared with 5419 who had cold hyperkalemic blood cardioplegia for isolated coronary artery grafting from 1996 through 2001. Creatine kinase-MB was measured preoperatively, at 90 min, and 7 hours after the end of extracorporeal circulation. Correlation of post-bypass creatine kinase-MB release with aortic crossclamp time and other variables in the two cardioplegia groups was made using dichotomous encoding of cardioplegia in a multivariate linear regression model. Creatine kinase-MB levels 90 min after bypass were higher in patients who had crystalloid cardioplegia than in those who had blood cardioplegia. There was a linear relationship between aortic crossclamp time and post-bypass creatine kinase-MB release in both cardioplegia groups. Post-bypass creatine kinase-MB release increased with aortic crossclamp time independently of other factors and significantly more with crystalloid cardioplegia than with blood cardioplegia (the slope of the regression line was 0.230 versus 0.106). Intraaortic balloon pumping was used less frequently in the blood cardioplegia group. There was an advantage with blood cardioplegia for myocardial protection in longer aortic crossclamp times for isolated coronary bypass grafting.