Multidose Cold Oxygenated Blood Is Superior to a Single Dose of Bretschneider HTK-Cardioplegia in the Pig

Comparison of "Huaxi-1" or "histidine-tryptophan-ketoglutarate" cardioplegia in an animal model

Background

Using a pig model of cardiopulmonary bypass, we compared outcomes after cardioplegia either with our in-house "Huaxi-1" solution containing natural blood and crystalloid or with the entirely crystalloid, commercially available "histidine-tryptophan-ketoglutarate" solution.

Methods

Cardiopulmonary bypass was established in 12 healthy male pigs, who were randomized to receive a single dose of either Huaxi-1 or entirely crystalloid. All animals were then subjected to whole-heart ischemia for 90 min, followed by 2 h of reperfusion, after which myocardial injury was assessed in terms of cardiac function, myocardial pathology and levels of biomarkers in plasma, while levels of high-energy phosphate in myocardium were assayed using liquid chromatography.

Results

Animals given Huaxi-1 cardioplegia required significantly less time to be weaned off bypass, they received significantly lower doses of norepinephrine, and they showed significantly higher levels (mean ± SD) of adenosine triphosphate (14 ± 4 vs. 8 ± 2 µg/mg, P = 0.005), adenosine diphosphate (16 ± 2 vs. 13 ± 2 µg/mg, P = 0.046), and total adenine nucleotide (37 ± 4 vs. 30 ± 3 µg/mg, P = 0.006) in myocardium after 2 h of reperfusion. They also showed less severe bleeding, edema and injury to mitochondria and myofibers in myocardium. The two groups did not differ significantly in doses of inotropic drugs received, cardiac output or levels of biomarkers in plasma.

Conclusions

In this animal model of healthy hearts subjected to 90 min of ischemia, Huaxi-1 cardioplegia may be superior to entirely crystalloid cardioplegia for promoting energy generation and attenuating ischemia/reperfusion injury in myocardium.

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.

Single-Dose St. Thomas Versus Custodiol® Cardioplegia for Right Mini-thoracotomy Mitral Valve Surgery

OBJECTIVE

Custodiol® and St. Thomas cardioplegia are widely employed in mini-thoracotomy mitral valve (MV) operations. One-dose of the former provides 3 h of myocardial protection. Conversely, St. Thomas solution is usually reinfused every 30 min and safety of single delivery is unknown. We aimed to compare single-shot St. Thomas versus Custodiol® cardioplegia.

METHODS

Primary endpoint of the prospective observational study was cardiac troponin T level at different post-operative time-points. Propensity-weighted treatment served to adjust for confounding factors.

RESULTS

Thirty-nine patients receiving St. Thomas were compared with 25 patients receiving Custodiol® cardioplegia; cross-clamping always exceeded 45 min. No differences were found in postoperative markers of myocardial injury. Ventricular fibrillation at the resumption of electric activity was more frequent following Custodiol® cardioplegia (P = .01).

CONCLUSION

Effective myocardial protection exceeding 1 h of ischemic arrest can be achieved with a single-dose St. Thomas cardioplegia in selected patients undergoing right mini-thoracotomy MV surgery.

Relevance and Recommendations for the Application of Cardioplegic Solutions in Cardiopulmonary Bypass Surgery in Pigs

Cardioplegic solutions play a major role in cardiac surgery due to the fact that they create a silent operating field and protect the myocardium against ischemia and reperfusion injury. For studies on cardioplegic solutions, it is important to compare their effects and to have a valid platform for preclinical testing of new cardioplegic solutions and their additives. Due to the strong anatomical and physiological cardiovascular similarities between pigs and humans, porcine models are suitable for investigating the effects of cardioplegic solutions. This review provides an overview of the results of the application of cardioplegic solutions in adult or pediatric pig models over the past 25 years. The advantages, disadvantages, limitations, and refinement strategies of these models are discussed.

Comparative Analysis of Myocardial Protection with HTK Solution and Hypothermic Hyperkalemic Blood Solution in the Correction of Acyanogenic Congenital Cardiopathies - A Randomized Study

OBJECTIVE

The goal of the present study was to compare the myocardial protection obtained with histidine-tryptophan-ketoglutarate (HTK) cardioplegic solution (Custodiol®) and with intermittent hypothermic blood solution.

METHODS

Two homogenous groups of 25 children with acyanotic congenital heart disease who underwent total correction with mean aortic clamping time of 60 minutes were evaluated in this randomized study. Troponin and creatine kinase-MB curves, vasoactive-inotropic score, and left ventricular function were obtained by echocardiogram in each group. The values were correlated and presented through graphs and tables after adequate statistical treatment.

RESULTS

It was observed that values of all the studied variables varied over time, but there was no difference between the groups.

CONCLUSION

We conclude that in patients with acyanotic congenital cardiopathies submitted to total surgical correction, mean aortic clamping time around one hour, and cardiopulmonary bypass with moderate hypothermia, the HTK crystalloid cardioplegic solution offers the same myocardial protection as the cold-blood hyperkalemic cardioplegic solution analyzed, according to the variables considered in our study model.

Lung Protection Strategies during Cardiopulmonary Bypass Affect the Composition of Blood Electrolytes and Metabolites-A Randomized Controlled Trial

Cardiac surgery with cardiopulmonary bypass (CPB) causes an acute lung ischemia-reperfusion injury, which can develop to pulmonary dysfunction postoperatively. This sub-study of the Pulmonary Protection Trial aimed to elucidate changes in arterial blood gas analyses, inflammatory protein interleukin-6, and metabolites of 90 chronic obstructive pulmonary disease patients following two lung protective regimens of pulmonary artery perfusion with either hypothermic histidine-tryptophan-ketoglutarate (HTK) solution or normothermic oxygenated blood during CPB, compared to the standard CPB with no pulmonary perfusion. Blood was collected at six time points before, during, and up to 20 h post-CPB. Blood gas analysis, enzyme-linked immunosorbent assay, and nuclear magnetic resonance spectroscopy were used, and multivariate and univariate statistical analyses were performed. All patients had decreased gas exchange, augmented inflammation, and metabolite alteration during and after CPB. While no difference was observed between patients receiving oxygenated blood and standard CPB, patients receiving HTK solution had an excess of metabolites involved in energy production and detoxification of reactive oxygen species. Also, patients receiving HTK suffered a transient isotonic hyponatremia that resolved within 20 h post-CPB. Additional studies are needed to further elucidate how to diminish lung ischemia-reperfusion injury during CPB, and thereby, reduce the risk of developing severe postoperative pulmonary dysfunction.

Normokalemic nondepolarizing long-acting blood cardioplegia

Objective Blood cardioplegia, the gold-standard cardioprotective strategy, requires frequent dosing, resulting in hyperkalemia-induced myocardial edema. The aim of our study was to compare the efficacy and safety of a long-acting blood-based cardioplegia with physiological potassium levels versus the well-established cold blood St. Thomas' Hospital no. 1 cardioplegia solution in multivalve surgeries. Methods One hundred patients undergoing simultaneous elective aortic and mitral valve replacement ± tricuspid valve repair were randomized in two groups. In group 1, adenosine 12 mg was given via the aortic root after crossclamping, followed by a single dose of long-acting solution at 14℃ (30 mLċkg^-1); in group 2, an initial 30 mLċkg^-1 of St. Thomas' cardioplegia at 14℃ was administered, followed by 15 mLċkg^-1 every 20 min. Duration of cardiopulmonary bypass, inotropic score, arrhythmias, ventilation time, and the levels of interleukin-6, creatinine kinase-MB, and troponin I were compared. Results Mean cardiopulmonary bypass and crossclamp times were 134.04 ± 36.12 vs. 154.34 ± 34.26 ( p = 0.004) and 110.37 ± 24.80 vs. 132.48 ± 31.68 min ( p = 0.002), respectively, in the long-acting and St. Thomas' groups. Cardiac index, creatinine kinase-MB and troponin I levels were comparable. Interleukin-6 levels post-bypass were 61.72 ± 15.33 and 75.44 ± 31.78 pgċmL^-1 ( p = 0.007) in the long-acting and St. Thomas' cardioplegia groups, respectively. Conclusions Single-dose long-acting cardioplegia gives a cardioprotective effect comparable to repeated doses of the well-established St. Thomas' Hospital no. 1 cold blood cardioplegia.

Clinical comparative analysis of histidine-tryptophan-ketoglutarate solution and St. Thomas crystalloid cardioplegia: A 12-year study from a single institution

Cardioplegic reperfusion during a long-term ischemic period interrupts cardiac surgery and increases cellular edema due to repeated administration. The present clinical study compared the protective effects of histidine-ketoglutarate-tryptophan (HTK) solution and St. Thomas crystalloid cardioplegia. Clinical experiences of the myocardial protection induced by one single perfusion with HTK were reviewed in high-risk patients with severe pulmonary arterial hypertension associated with complex congenital heart disease. This retrospective study included 88 high-risk patients (aortic cross-clamp time, >120 min) between March 2001 and July 2012. The cohort was divided into two groups according to the technique used. Either myocardial protection was performed with one single perfusion with HTK solution (HTK group) or with conventional St. Thomas crystalloid cardioplegia (St group). The duration of cardiopulmonary bypass did not differ between the two groups. The mortality, morbidity, intensive care unit (ICU) stay, postoperative hospitalization, and transfusions of HTK group are significantly lower than those of the St group (P<0.05). Univariate and multivariate analysis demonstrated that HTK is a statistically significant independent predictor of decreased early mortality and morbidity (P<0.05). In conclusion, the present findings suggested that HTK solution decreases mortality, morbidity, ICU stay, postoperative hospitalization, and transfusions in high-risk patients with severe pulmonary arterial hypertension associated with complex congenital heart disease.

Haemodynamic differences between pancuronium and vecuronium in an experimental pig model

OBJECTIVE

To compare baseline cardiovascular function in anesthetised pigs using either pancuronium or vecuronium as a neuromuscular blocker.

STUDY DESIGN

Retrospective, non-randomized comparison.

ANIMALS

Norwegian Land Race pigs (Sus scrofa domesticus) weighing mean 42 ± SD 3 kg.

METHODS

One hundred and sixteen animals from four different research protocols premedicated with identical doses of ketamine, diazepam, atropine and isoflurane, and anaesthetised with pentobarbital, fentanyl, midazolam and N(2)O were arranged into three uniform groups with respect to neuromuscular blocking agent: pancuronium bolus of 0.063 mg kg(-1) followed by 0.14 mg kg(-1) hour(-1) (n = 54), low-dose vecuronium 0.4 mg kg(-1) /0.2 mg kg(-1) hour(-1) (n = 29) and high-dose vecuronium 0.6 mg kg(-1) /0.3 mg kg(-1) hour(-1) (n = 33).

RESULTS

The majority of cardiovascular parameters demonstrated no significant differences between groups. For heart rate, there was an overall group difference, p = 0.036. Dromotropy was low in the pancuronium group, with an increased normalised PR-interval compared to the high-dose vecuronium group, median 0.200 interquartile range (0.190, 0.215) versus 0.182 (0.166, 0.199), p < 0.05. Left ventricular compliance was increased in pancuronium-treated animals, demonstrated as a reduction in the nonlinear end-diastolic pressure volume relationship β compared to both vecuronium groups, 0.021 (0.016, 0.025) versus 0.031 (0.025, 0.046) and 0.031 (0.022, 0.048), p < 0.05. The linear end-diastolic pressure volume relationship EDPVR(lin) was reduced as well in the pancuronium group, compared to the low-dose vecuronium group, 0.131 (0.116, 0.169) versus 0.181 (0.148, 0.247), p < 0.05.

CONCLUSIONS

There are only minor haemodynamic differences when using pancuronium compared to vecuronium in the fentanyl-pentobarbital-midazolam-N(2)O anesthetised domestic pigs. Furthermore, increasing doses of vecuronium have minimal haemodynamic effects.

CLINICAL RELEVANCE

Experimental studies in pigs using either pancuronium or vecuronium as a neuromuscular blocking agent are comparable with regard to cardiac and haemodynamic performance.

Custodiol for myocardial protection and preservation: a systematic review

INTRODUCTION

Custodiol cardioplegia is attractive for minimally invasive cardiac surgery, as a single dose provides a long period of myocardial protection. Despite widespread use in Europe, there is little data confirming its efficacy compared with conventional (blood or crystalloid) cardioplegia. There is similar enthusiasm for its use in organ preservation for transplant, but also a lack of data. This systematic review aimed to assess the evidence for the efficacy of Custodiol in myocardial protection and as a preservation solution in heart transplant.

METHODS

Electronic searches were performed of six databases from inception to October 2013. Reviewers independently identified studies that compared Custodiol with conventional cardioplegia (blood or extracellular crystalloid) in adult patients for meta-analysis; large case series that reported results using Custodiol were analyzed. Next, we identified studies that compared Custodiol with other organ preservation solutions for organ preservation in heart transplant.

RESULTS

Fourteen studies compared Custodiol with conventional cardioplegia for myocardial protection in adult cardiac surgery. No difference was identified in mortality; there was a trend for increased incidence of ventricular fibrillation in the Custodiol group that did not reach statistical significance. No difference was identified in studies that compared Custodiol with other solutions for heart transplant.

CONCLUSIONS

Despite widespread clinical use, the evidence supporting the superiority of Custodiol over other solutions for myocardial protection or organ preservation is limited. Large randomised trials are required.

The "tube-in-tube" circuit: a new method for delivering cold blood cardioplegia in neonates and small infants

PURPOSE

To conceive a method to deliver cold blood cardioplegia in neonates and young infants.

DESCRIPTION

The "tube-in-tube" circuit consists of a 3-mm line (bloodline) which is inserted inside a 1/2 -in tube where cold water flows continuously (waterline). This circuit includes a filling volume of 18 mL of static prime and 15 mL for the collecting line (pump raceway). Several temperature samples were taken at different blood flows from 20 to 100 mL/min.

EVALUATION

Temperatures (in °C) at the needle tip were significantly lower when using the tube-in-tube cooling circuit if compared to standard cardioplegia circuit at flows up to 60 mL/min.

CONCLUSIONS

The tube-in-tube circuit proved to be an effective strategy for low-flow cardioplegia delivery (<60 ml/min), which is particularly useful in neonates and young infants; the lower is the flow, the better is the cooling effect on the cardioplegia.

Randomized trial of HTK versus warm blood cardioplegia for right ventricular protection in mitral surgery

OBJECTIVES

To clarify the reliability of the one-shot histidine-tryptophane-ketoglutarate (HTK) cardioplegia for right ventricular (RV) myocardial protection during mitral surgery, in patients with or without pre-operative RV dysfunction.

DESIGN

Sixty patients undergoing isolated mitral surgery were randomized to myocardial protection with either one-shot HTK or intermittent warm blood cardioplegia (WBC). The RV function was assessed by echocardiography and hemodynamic assessment. Pre-operative tricuspid annular plane systolic excursion (TAPSE), an index of RV systolic function was used to dichotomize groups into patients having impaired (TAPSE < 15) or preserved (TAPSE ≥ 15) RV function.

RESULTS

There were no significant intergroup differences in the post-operative indexes of RV function in cases with TAPSE ≥ 15. In patients having TAPSE < 15 we observed statistically worse RV ejection fraction (RVEF, 15% ± 2% vs. 24% ± 3%), end-diastolic volume (RVEDV, 188 mL ± 20 vs. 179 mL ± 14) and fractional area change (RVFAC, 21% ± 6% vs. 30% ± 3%) after use of the HTK solution versus patients who received the WBC. These differences were associated with longer mechanical ventilation and ICU times in patients with impaired RV function and receiving HTK cardioplegia. In a substudy ten patients with TAPSE < 15 received intra-operative topical myocardial cooling in addition to HTK. The addition of topical cooling to HTK cardioplegia yielded statistically significant amelioration in post-operative RV function compared with patients who received the HTK solution without topical cooling (RVEF: 23% ± 3% vs. 15% ± 2%; RVEDV: 180 mL ± 9 vs. 188 mL ± 18; RVFAC: 8.5% ± 1% vs. 6% ± 2%).

CONCLUSIONS

The one shot HTK solution offers inferior RV protection compared with WBC, mainly in patients with depressed pre-operative RV function. When adopting HTK cardioplegia the addition of topical cooling is strongly advised.

Which is the better option during neonatal cardiopulmonary bypass: HTK solution or cold blood cardioplegia?

The optimal myocardial protection strategy for newborns/infants undergoing congenital heart surgery remains controversial. The purpose of this study was to compare myocardial protection using histidine-tryptophan-ketoglutarate (HTK) and cold blood cardioplegia in a neonatal piglet model. Twenty-one piglets were randomized to three groups: the control group (C group, n = 7), a single dose of HTK group (H group, n = 7), and multidose cold blood cardioplegia group (B group, n = 7). Animals in the two experimental groups were placed on hypothermic cardiopulmonary bypass, after which the ascending aorta was clamped for 2 hours. Immediately after declamping, both the difference between arterial and coronary sinus blood lactate concentrations and the oxygen extraction did not differ between the H group and the B group. At 3 hours after declamping, rise in serum troponin-T and creatine kinase isoenzyme MB levels showed no significant differences between the H group and the B group (p = 0.735 and p = 0.103, respectively). No significant differences were noted in the myocardial lactate content, ATP content, and histopathological score between the H group and the B group (p = 0.810, p = 0.158, and p = 0.399, respectively). Transfusion requirement in the B group was significantly more than that in the H group (p = 0.003). HTK solution provides equivalent myocardial protection to multidose cold blood cardioplegia for the neonatal heart with less transfusion requirement.

Custodiol versus blood cardioplegia in complex cardiac operations: an Australian experience

OBJECTIVES

A single or dual-dose strategy for myocardial protection is attractive in long operations, in avoiding the need to interrupt the procedure to re-administer cardioplegia. We hypothesized that a single administration of Bretschneider histidine-tryptophan-ketoglutarate (HTK) crystalloid solution (Custodiol) offers myocardial protection comparable with repeated tepid blood cardioplegia.

METHODS

We reviewed a prospectively compiled single-centre database containing all adult cardiac procedures performed from January 2005 to January 2011. Preoperative demographic and investigative data, operative variables and postoperative (30-day) mortality and morbidity were compared between the Custodiol and blood cardioplegia groups. The study primary endpoints were 30-day mortality, return to the operating theatre, myocardial infarction, stroke, postoperative requirement for an intra-aortic balloon pump, new renal failure, prolonged ventilation and re-admission to hospital within 30 days. Propensity score matching was performed to correct for any bias that may have been associated with the usage of Custodiol.

RESULTS

A total of 1900 cardiac surgical procedures were identified of which 126 (7%) utilized Custodiol and 1774 (93%) used blood cardioplegia as the primary cardioplegic agent. After propensity-score matching, we were able to match 71 Custodiol cases one-to-one to those receiving blood cardioplegia. There were no statistically significant differences noted for any of the endpoints studied after propensity-score matching. In particular, the proportion of mortality (blood cardioplegia: 1 vs Custodiol 4%, P = 0.63) any mortality/morbidity (blood cardioplegia: 35 vs Custodiol: 39% P = 0.46) was similar between the groups.

CONCLUSIONS

The use of Custodiol is convenient, simple and at least as safe as tepid blood cardioplegia for myocardial protection in complex cardiac operations. A randomized prospective comparison of myocardial protection strategies is warranted.

Myocardial protection during aortic surgery: comparison between Bretschneider-HTK and cold blood cardioplegia

The ideal cardioplegic strategy in thoracic aorta operations requiring long cardiopulmonary bypass and cross-clamp time has not been established. Suboptimal myocardial protection may lead to myocardial damage and possible post-operative complications. We evaluate post-operative cardiac Troponin I (cTnI) release, low cardiac output syndrome (LCOS) and mortality, using a cold crystalloid single-dose intracellular or cold blood multidose cardioplegia in 112 elective or emergent thoracic aorta operation patients. Fifty-four patients (HTK group) received Custodiol® cardioplegic solution and 58 received cold blood cardioplegia (CB group). Cross-clamp time, cardiopulmonary bypass (CPB) time and cTnI peak release were similar in both groups. No differences were found for atrial and ventricular arrhythmias, inotropic support, LCOS and in-hospital mortality. Two-way ANOVA analysis revealed an interactive effect on cTnI peak (p=0.012) of cardioplegic solution type across the cross-clamp time quintile. In the fifth quintile, cross-clamp time patient (>160 min) cTnI peak value was higher in CB patients (p=0.044). HTK and CB cardioplegic solutions assure similar myocardial protection in patients undergoing thoracic aorta operations. In long cross-clamp times, the lower post-operative cTnI release detected using HTK may be indicative of a better myocardial protection in these extreme conditions.

One single dose of histidine-tryptophan-ketoglutarate solution gives equally good myocardial protection in elective mitral valve surgery as repetitive cold blood cardioplegia: a prospective randomized study

OBJECTIVES

Histidine-tryptophan-ketoglutarate (HTK-Custodiol) cardioplegic solution is administered as one single dose for more than 2 hours of ischemia. No prospective randomized clinical study has compared the effects of HTK and cold blood cardioplegia on myocardial damage in elective mitral valve surgery. Thus, the main aim of the present study was to examine whether one single dose of cold antegrade HTK gives as good myocardial protection as repetitive antegrade cold blood cardioplegia in mitral valve surgery.

METHODS

Eighty consecutive patients undergoing elective isolated mitral valve surgery for mitral regurgitation, with or without ablation for atrial fibrillation, were included in the study and randomized to HTK or blood cardioplegia. Markers of myocardial injury (troponin-T and creatine kinase MB) were analyzed at baseline and 7 hours, 1 day, 2 days, and 3 days after surgery.

RESULTS

No significant difference in creatine kinase MB and troponin-T between HTK and blood cardioplegia groups was found at any time point. There was a significant correlation between ischemic time and markers of myocardial injury in the HTK group only and significantly more spontaneous ventricular fibrillation after release of crossclamping in the HTK group.

CONCLUSIONS

One single dose of antegrade cold HTK cardioplegic solution in elective mitral valve surgery protects the myocardium equally well as repetitive antegrade cold blood cardioplegia.