Del nido cardioplegia in adults: a retrospective observational study in comparison to modified St. Thomas cardioplegia in cardiac surgery

BACKGROUND

St. Thomas cardioplegia is commonly administered to adults, yet repeated dosing at brief intervals is required. Del Nido's cardioplegic solution provides a prolonged duration of safe myocardial arrest, yet it was primarily intended for pediatric cardiac surgery. Recently, there has been an increasing interest in using Del Nido's in adults; this might be due to its ease of administration and extended re-dosing intervals. This study contrasted Del Nido's to modified St. Thomas cardioplegia in adults.

METHODS

This study was conducted on 200 patients. Troponin-T was the primary outcome within the first 24 and 48 h post-surgery. Cardiopulmonary bypass time, cross-clamp time, intraoperative use of inotropic support, defibrillator and/or intra-aortic balloon were the secondary outcomes of the study.

RESULTS

There was a significant reduction in post-operative Troponin-T levels in the first 24 and 48 h within Del Nido's group compared to the modified St. Thomas group. The cross-clamp and cardiopulmonary bypass times were also found to be lower within Del Nido's group.

CONCLUSION

This study has demonstrated a significant reduction in early postoperative Troponin-T levels as well as operative times favoring Del Nido's in adults.

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.

Comparison of Clinical Outcomes between del Nido Cardioplegia and Microplegia among Patients Undergoing Elective Mitral Valve Replacement

BACKGROUND

Cardioplegia solutions are used to protect the myocardium from ischemic injury caused by cardiopulmonary bypass and various types of cardioplegia solutions have been introduced for cardiac surgery. In this study, we aimed to compare the effects of del Nido cardioplegia and microplegia, which were mostly used in our clinic for intraoperative and postoperative processes among patients who underwent elective mitral valve replacement. As a result, the comparison could be performed in a specific patient group without additional valvular or coronary disease, and cardioplegia distribution could be achieved more efficiently.

METHODS

Between 2018 and 2023, a total of 120 patients who underwent elective mitral valve replacement via sternotomy with del Nido cardioplegia or microplegia were included in the study. Patients were divided into two groups; group 1 (del Nido, n = 64) and group 2 (microplegia, n = 56). Preoperative characteristics, intraoperative and postoperative early clinical data as primary outcomes, and postoperative mortality rates and intensive care costs as secondary outcomes were compared statistically.

RESULTS

There were no statistically significant differences in terms of preoperative characteristics between the two groups. Duration of cross clamp differences between group 1 versus group 2 (45 ± 16 vs. 57 ± 19 min), cardiopulmonary bypass (56 ± 17 vs. 65 ± 21 min), intensive care length of stay (18.04 ± 7.41 vs. 22.37 ± 6.86 h), requirement of intraoperative defibrillation (n = 5 vs. n = 13), and intensive care costs were found to be statistically significantly lower in del Nido group.

CONCLUSION

Either del Nido or microplegia solutions can be used safely in mitral valve replacement operations, however, del Nido cardioplegia has some advantages over intraoperative processes, such as lowering the cross clamp and cardiopulmonary bypass time. Furthermore, patients who received del Nido cardioplegia had shorter intensive care stay and required less intraoperative defibrillation compared with the microplegia group. Therefore, less exposure to anesthesia, the prevention of infection due to shortened operation duration, and greater cost-effectiveness can be achieved by using del Nido cardioplegia instead of microplegia.

[Myocardial protection of del Nido cardioplegia in adult cardiac and major vascular surgery with long aortic cross-clamp time]

Objective: To explore the safety and myocardial protection efficacy of del Nido cardioplegia in adult cardiac and major vascular surgery with long aortic cross-clamp (ACC) time. Methods: A total of 2 536 patients who underwent adult cardiac and major vascular surgery with ACC time>90 min at Beijing Anzhen Hospital from March 2018 to March 2023 were collected. The patients were divided into two groups according to the type of cardioplegia solution: the del Nido cardioplegia solution group (DC group) and the cold blood cardioplegia solution group (BC group). Preoperative baseline data of the patients (age, gender, comorbidities, ejection fraction, etc) were adjusted using propensity score matching (PSM). Cardiopulmonary bypass (CPB) time, ACC time, total amount of cardioplegia solution, in-hospital mortality rate, length of intensive care unit (ICU) stay, mechanical ventilation time, postoperative complications, left ventricular ejection fraction, and troponin levels were compared between the two groups. Results: After PSM, a total of 306 patients were included, including 223 males and 83 females, with a mean age of (52.0±12.3) years. There were 153 cases in the DC group and 153 cases in the BC group. Compared with the DC group, the cross-clamp time was longer [109(100, 150) min vs 102(91, 133) min, P<0.001], the rate of return to spontaneous rhythm was lower [51.6% (79/153) vs 86.9%(133/153), P<0.001], and intraoperative peak glucose was higher [12.6 (6.5, 15.9) mmol/L vs 10.1 (8.5, 12.4) mmol/L, P=0.005] in the BC group. In addition, perioperative mortality [4.6% (7/153) vs 3.3% (5/153), P=0.132], stroke[3.9% (6/153) vs 3.3% (5/153), P=0.759], renal insufficiency [3.3% (5/153) vs 6.5% (10/153), P=0.186], atrial fibrillation [4.6% (7/153) vs 2.6% (4/153), P=0.652] and low cardiac output syndrome [3.9% (6/153) vs 4.6% (7/153), P=0.716] did not differ between the two groups. Compared with BC group, DC group had lower level of high sensitivity troponin (hsTnI) [1.2 (0.8, 1.8) μg/L vs 1.3 (0.9, 2.3) μg/L, P=0.030] and creatine kinase isoenzyme (CK-MB) [31.0 (20.0, 48.9) μg/L vs 37.0 (24.0, 58.9) μg/L, P=0.011] at 24 h postoperatively, and shorter length of ICU stay [35.6 (19.8, 60.5) h vs 42.6 (21.9, 83.6) h, P=0.015] and mechanical ventilation time [20.5 (15.5, 41.0) h vs 31.5 (17.1, 56.0) h, P=0.012]. Subgroup analysis showed that in the 120-180 minute subgroup, patients in the DC group had a shorter cross-clamp time [132 (124, 135) min vs 136 (124, 138) min, P<0.001], while levels of hsTnI [1.6 (1.1, 2.0) μg/L vs 1.4 (1.0, 2.6) μg/L, P=0.030] and CK-MB [38.8 (23.5, 55.5) μg/L vs 37.0 (24.5, 62.3) μg/L, P=0.011] were higher than those in the BC group. Conclusions: In adult cardiac and major vascular surgery with ACC times>90 min, comparable myocardial protection is observed with the use of DC compared with BC. Additional advantages in glycemic control, return to spontaneous rhythm, and improved surgical procedures make DN an attractive alternative for myocardial protection in adult cardiac surgery.

Outcomes of coronary artery bypass surgery using modified del Nido cardioplegia in patients with poor ventricular function

BACKGROUND

del Nido cardioplegia (DN) has been shown to be safe in adult patients undergoing isolated coronary artery bypass grafting with normal left ventricular ejection fraction. We sought to determine whether it was also safe in adult patients with diminished left ventricular function.

METHODS

All patients with preoperative left ventricular ejection fraction ≤ 40% undergoing isolated coronary artery bypass grafting between 1/1/2019 and 7/10/2022 were retrospectively analyzed. Off-pump and beating heart cases were excluded. Patients were divided by surgeon preference between conventional cardioplegia (CCP) and DN. Baseline and intraoperative characteristics and short-term postoperative outcomes were compared.

RESULTS

Six surgeons performed 829 isolated coronary artery bypass operations during the study. Two-hundred seventy-two met study criteria. Three surgeons used exclusively CCP for the duration of the study, two used exclusively DN and one switched from CCP to DN mid-way through. Group totals were: CCP n = 181 and DN n = 91. There were no significant differences in baseline characteristics including mean left ventricular ejection fraction (CCP 32.5 ± 7.4% vs. DN 33.4 ± 7.29%, p = 0.939). Other than a significant decrease in bypass time for DN (113.20 ± 37.2 vs. 122.43 ± 34.3 min, p = 0.043) there were no intergroup differences in urgency, number of grafts, ischemic time or incidence of blood transfusion. Postoperative outcomes between CCP and DN were similar including incidence of atrial fibrillation (12.2% vs. 8.8%, p = 0.403), intensive care length of stay (3.7 ± 2.3 vs. 4.3 ± 3.7 days, p = 0.886), total length of stay (5.7 ± 3.7 vs. 6.3 ± 4.4 days, p = 0.922) and 30-day mortality (3.85% vs. 1.10%, p = 0.205).

CONCLUSION

Compared to conventional cardioplegia, del Nido cardioplegia provides equivalent short-term outcomes in patients with low left ventricular ejection fraction undergoing isolated coronary artery bypass grafting.

Microplegia in paediatric hearts

INTRODUCTION

A basic prerequisite for a good surgical outcome in heart surgery is optimal myocardial protection. However, cardioplegia strategies used in adult cardiac surgery are not directly transferable to infant hearts. Paediatric microplegia, analogous to Calafiore cardioplegia used in adult cardiac surgery, offers the advantage of safe myocardial protection without haemodilution. The use of concentration-dependent paediatric microplegia is new in clinical implementation.

MATERIAL AND METHODS

Paediatric microplegia has been in clinical use in our institution since late 2014. It is applied via an 1/8 inch tube of a S5-HLM roller pump (LivaNova, Italy). As cardioplegic additive, a mixture of potassium (K) 20 mL (2 mmol/mL potassium chloride 14.9% Braun) and magnesium (Mg) 10 mL (4 mmol/mL Mg-sulphate Verla® i. v. 50%) is fixed into a syringe-pump (B. Braun, Germany). This additive is mixed with arterial patient blood from the oxygenator in different flowdependent ratios to form an effective cardioplegia.

TECHNIQUE

After microplegia application of initially 25 mmol/L K with 11 mmol/L Mg for 2 min, a safe cardioplegic cardiac arrest is achieved, which after release of the coronary circulation, immediately returns to a spontaneous cardiac-rhythm. In the case of prolonged aortic clamping, microplegia is repeated every 20 min with a reduction of the application dose of K by 20% and Mg by 30% (20 mmol/L K; 8.5 mmol/L Mg) and a further reduction down to a maintenance dose (15 mmol/L K; 6 mmol/L Mg) after additional 20 min.

SUMMARY

The microplegia adapted to the needs of paediatric myocardium is convincing due to its simple technical implementation for the perfusionist while avoiding haemodilution. However, the required intraoperative interval of microplegia of approx. 20 min demands adapted intraoperative management from the surgeon.

Del Nido Cardioplegia in Ascending Aortic Surgery

Del Nido cardioplegia offers equivalent myocardial protection and clinical outcomes to blood cardioplegia in adult isolated CABG and valve patients, but the safety and efficacy of del Nido in complex cases with prolonged aortic cross-clamp times is still unknown. 443 patients at our center underwent replacement of the ascending aorta using either del Nido (n = 182) or blood (n = 261) cardioplegia. Two surgeons used del Nido exclusively and 6 used blood exclusively over the study period. Propensity matching of preoperative characteristics yielded 172 well matched pairs. Emergency and reoperative cases were included. Clinical data were extracted from our local database. Troponin levels were drawn at 12 hours postop in all patients. Rates of perioperative mortality (4.7% vs 5.2%), stroke (5.8% vs 7.0%), renal failure (11.6% vs 12.2%), atrial fibrillation (36.0% vs 31.4%), intra-aortic balloon pump insertion (2.3% vs1.2%), and extra corporeal membrane oxygenation use (4.7% vs 4.1%) did not differ between blood and del Nido groups. Postop Troponin T levels were 0.50[0.35, 0.86] ng/mL and 0.40[0.20, 0.70] ng/mL for blood and del Nido, respectively (P < 0.0001). Postop echocardiography was available in 333 of 344 (96.8%) patients, and there was no difference in change in EF from pre- to postop between blood 0.0[-6.0, 5.0]% and del Nido 0.0 [-6.0, 3.5]% (P = 0.201). Subgroup analysis of patients with aortic cross-clamp time greater than 180 minutes (blood = 77, del Nido = 27) revealed no difference in troponins, ejection fraction, or clinical outcomes. Five-year survival was 85.9[76.8, 91.7]% and 79.8[71.2, 86.1]% for blood and del Nido, respectively (P = 0.151). In ascending aortic surgery with prolonged operative times, no differences were observed in myocardial protection or clinical outcomes with the use of del Nido cardioplegia compared to blood cardioplegia.

Myocardial Protection in Adult Cardiac Surgery With del Nido Versus Blood Cardioplegia: A Systematic Review and Meta-Analysis

BACKGROUND

Myocardial protection in adult cardiac surgery is commonly achieved with either multidose blood cardioplegia or single-dose del Nido crystalloid cardioplegia.

AIM

The aim of this systematic review and meta-analysis was to compare the outcomes of del Nido cardioplegia versus blood cardioplegia in adult cardiac surgery.

METHOD

All English-language articles were searched in MEDLINE (PubMed), the Cochrane Central Register of Controlled Trials (CENTRAL), and Google Scholar up to March 2020, to identify randomised control trials, prospective observational studies, and retrospective analyses (with or without propensity matching) reporting any or all of the primary and secondary endpoints. The primary endpoint was all-cause mortality. Secondary endpoints included cardiopulmonary bypass (CPB) and aortic cross-clamp (AoX) time; cardioplegia volume; need for defibrillation after AoX release; intraoperative glucose; postoperative myocardial enzyme release; postoperative left ventricular ejection fraction (LVEF); incidence of postoperative acute kidney injury (AKI), atrial fibrillation (AF), stroke, and low cardiac output syndrome (LCOS); postoperative blood transfusion; duration of mechanical ventilation; and length of intensive care unit (ICU) and hospital stay.

RESULTS

Twenty-nine (29) studies were included. There was no difference in the primary outcome of mortality between the two groups (odds ratio [OR], 1.18; 95% confidence interval [CI], 0.82-1.72 [p=0.37]). del Nido cardioplegia was associated with significantly shorter CPB (mean difference [MD], -7.42 minutes; 95% CI, -12.53 to -2.31 [p=0.004]) and AoX times (MD, -6.39 minutes; 95% CI, -10.30 to -2.48 [p=0.001]), and lower cardioplegia volumes. Significantly fewer patients required defibrillation after AoX release in the del Nido group. Intraoperative glucose homeostasis was better preserved in the del Nido group. Postoperative cardiac troponin T release and the number of patients needing transfusions were less in the del Nido group. No differences were seen in postoperative LVEF, or in the incidence of AKI, stroke, AF, and LCOS. Duration of mechanical ventilation, and length of ICU and hospital stay were similar.

CONCLUSIONS

Although this meta-analysis failed to find any mortality benefits with del Nido cardioplegia, significant benefits were seen in a number of intraoperative and postoperative variables. del Nido cardioplegia is a safe and favourable alternative to blood cardioplegia in adult cardiac surgery.

Use of del Nido Cardioplegia for Adult Heart Surgery: How Long Is Not Too Long?

The most apparent practical advantage of del Nido cardioplegia (DNC) is that it allows the surgeon a longer arrest period before a subsequent dose is needed, as opposed to the conventional St. Thomas' cardioplegia solution where the recommended ischemic time is ∼15-20 minutes. In this study, we explored the incidence of arrhythmia after cross-clamp removal as a surrogate for a safe myocardial ischemic time with the use of DNC in adult heart surgery. A total of 113 patients who had undergone heart valve repair and/or replacement surgery at the National University Hospital, Singapore, were investigated. This single-center retrospective study was conducted on a population where DNC had been used for myocardial protection between January 2017 and April 2019. Cardioplegia ischemic time interval groups were not significant predictors of postoperative arrhythmia, defibrillation, and intraoperative intra-aortic balloon pump usage. Crude comparison of postoperative outcomes showed no significant differences in any other postoperative variables, including mortality and total hospital stay. From the results of the present study, it appears that there is no optimal ischemic time interval for the administration of DNC within a 120-minute time period. It is likely that DNC has a redosing interval of, and may provide adequate myocardial protection, for up to 120 minutes.

Lactated Ringer's as a Base Solution for del Nido Cardioplegia

Unavailability of Plasma-Lyte A precludes the utility of traditional del Nido cardioplegia in many countries. This observational study aimed to evaluate myocardial preservation and clinical outcomes when using lactated Ringer's solution as the base solution for del Nido cardioplegia as compared with our institute's standard blood cardioplegia strategy. Eighty-nine adult patients underwent cardiac surgery for acquired heart disease from February 2017 to November 2017 either with del Nido cardioplegia (n = 44) or blood cardioplegia (n = 45). Clinical data and outcomes were compared. Patient characteristics were similar between groups. Troponin T release was lower in the del Nido group on postoperative day 1 (.632 [.437, .907] vs. .827 [.599, 1.388] ng/mL; p = .009) and day 2 (.363 [.250, .451] vs. .549 [.340, .897] ng/mL; p = .002). The del Nido group exhibited lower total volume of cardioplegia administered (1,075 [1,000, 1,250] vs. 3,400 [2,700, 3,750] mL; p < .0001), fewer doses (1.6 ± .7 vs. 4.6 ± 1.3; p < .0001), and a decreased incidence of ventricular fibrillation after aortic cross-clamp removal (9.09 vs. 31.11%; p = .01). The del Nido group had shorter intensive care unit stays (2 [1, 2] vs. 3 [2, 4] days; p < .0001), hospital stays (7 [6, 10] vs. 9 [7, 10] days; p = .0002), less vasopressor and inotropic support (1 [1, 1] vs. 1 [1, 2] days; p = .0001), and lower incidence of postoperative atrial fibrillation/flutter (25 vs. 46.7%; p = .033). No mortality occurred and clinical outcomes were similar. The use of traditional del Nido cardioplegia ingredients added to lactated Ringer's as the base solution provided either similar or superior myocardial protection than our blood cardioplegia strategy depending on the outcome measure analyzed. The use of lactated Ringer's as a base solution may be an option for centers that do not have access to Plasma-Lyte. Further investigation and follow-up are warranted after this observational study.

Safe minimization of cardiopulmonary bypass circuit volume for complex cardiac surgery in a 3.7 kg neonate

Over recent years, increasing awareness has been aroused to the hazards of the utilization of donor blood products. Particularly in neonate cardiac surgery employing cardiopulmonary bypass (CPB), the relative high priming volume of the CPB system and its adjunctive components, such as hemofilters, causes severe hemodilution and, therefore, particularly during extended perfusions, customarily requires priming of the system with autologous blood components. We report on our efforts to minimize the CPB system and adjust the perfusion strategy to the goal of transfusion-free CPB in a 3.7 kg neonate scheduled for repair of transposition of the great arteries.

del Nido versus St. Thomas Cardioplegia Solutions: A Single-Center Retrospective Analysis of Post Cross-Clamp Defibrillation Rates

There are many cardioplegia solutions currently in use for pediatric cardiopulmonary bypass (CPB). The most common being del Nido solution. Another common cardioplegia solution used for pediatric CPB is St. Thomas. In October 2014, Children's Mercy Kansas City changed from the use of modified St. Thomas to del Nido. This study compared rates of post cross-clamp fibrillation requiring defibrillation between del Nido solution and modified St. Thomas solution stratified by weight at Children's Mercy Kansas City. This retrospective study consisted of 394 patients who underwent cardiac surgery requiring cardioplegia between January 1, 2014 and July 31, 2015. The outcome measured was defibrillation upon cross-clamp removal. Statistical significance was determined using Fishers exact test with a two-sided significance level of .05. Incidence of defibrillation post cross-clamp removal was 4.4% in the del Nido group and 26.8% in the St. Thomas group (p < .0001). Analysis by weight stratifications displays a reduction in post cross-clamp defibrillation rates in groups using the del Nido solution. The 0- to 6-kg category had an incidence of fibrillation of 1.23% in the del Nido group and 17.5% in the St. Thomas group (p < .0003). The 6- to 15-kg category had an incidence of defibrillation of 1.82% in the del Nido group and 14% in the St. Thomas group (p < .0198). The 15- to 60-kg category had an incidence of defibrillation of 8.9% in the del Nido group and 61% in the St. Thomas group (p < .0001). The >60-kg category had an incidence of defibrillation of 16.7% in the del Nido group and 63% in the St. Thomas group (p < .0623). This study demonstrates a 6-fold decrease in the overall rate of defibrillation post cross-clamp removal between St. Thomas and del Nido cardioplegia solutions. Analyses of weight stratifications demonstrate a decrease in the rate of defibrillation post cross-clamp removal in all categories within the del Nido group.

Cold Agglutinin Autoantibodies in a Patient without a Visible Coronary Sinus Ostium: Strategies for Myocardial Protection without Using Retrograde Cardioplegia

The presence of cold agglutinins (CA) during cardiac surgery with cardiopulmonary bypass usually creates the need for an altered surgical plan. In this case, the CA were discovered after the initiation of bypass, limiting the time, and cardioplegia solutions that could be used in the new approach. The inability to cannulate the coronary sinus with a retrograde cardioplegia catheter excluded the standard approach to myocardial preservation with CA of using continuous warm blood. For this case, we used intermittent cold crystalloid delivered via the antegrade needle for the first half of the procedure and through the saphenous vein graft anastomosis during the aortic valve portion of the cross-clamp period.

Custodial-HTK Solution for Myocardial Protection in CABG Patients

BACKGROUND

Many steps of myocardial preservation during open heart surgery are practical after the development of the heart-lung machine. A cardioplegia solution, infused after aortic cross clamping, is an important aspect. Two-thirds of cardioplegia solutions are an intracellular solution (such as HTK or Bretschneider solution) or extracellular solution (such as blood cardioplegia). Intracellular cardioplegia solution can provide protection for 3-4 hours after one-time infusion, which differs from extracellular cardioplegia solution requiring intermittent use every 20-30 minutes.

MATERIAL AND METHOD

Retrospective case-control study in CABG patients were reviewed in Cardiovascular and Thoracic Unit, Department of Surgery, Khon Kaen University during April 2011 and September 2012. The study group was divided into groups A and B, for myocardial protection by blood cardioplegia and Custodiol-HTK (Histidine-Tryptophan-Ketoglutarate) solutions. Baseline data such as age, sex, NYHA, risk factors, associated disease, operation, CPB time, aortic cross clamp time, complication, defibrillation after surgery, ICU stay, length of stay and mortality rate were analyzed.

RESULTS

The study patients in groups A and B were 60 and 65 cases. Defibrillation after finishing CABG in groups A, B was 8.3% and 33.8%. Mortality rate in groups A, B were 1.7% and 4.6%. Other post operative complications were similar in both groups.

CONCLUSION

There was significantly more spontaneous ventricular fibrillation after release of cross clamping in HTK group. Clinical outcome of single doses of antegrade, cold Custodiol-HTK cardioplegia solution in CABG surgery protected the myocardium equally well as repetitive antegrade, cold blood cardioplegia.

Design and Evolution of the Asporto Heart Preservation Device

The Asporto Heart Preservation Device is a system providing perfusion of cardioplegia to the donor heart using a computer-controlled peristaltic pump in a thermoelectrically cooled and insulated container. In 1998, a user interface was developed at the University of Minnesota consisting of a touch screen and battery-backed microcontroller. Power was supplied by a 120 VAC to 12 VDC converter. An upgrade to the insulated cooler and microcontroller occurred in 2002, which was followed by proof of concept experimental pre-clinical transplants and tests demonstrating the efficacy of the device with isolated donor hearts. During the period between 2002 and 2006, a variety of donor organ containers were developed, modified, and tested to provide an optimal sterile environment and fluid path. Parallel development paths encompass formalized design specifications for final prototypes of the touch screen/microcontroller, organ container, and thermoelectric cooler.

It is time to take industrial action to reverse the sell-off of the NHS

As a nurse at St Thomas' Hospital in London during the strikes in the 1980s, I never wanted to strike, having seen the effects on patient care (Letters May 21).

[Comparison of the cardioprotection between crystalloid and blood cardioplegia in adult patients undergoing cardiac surgery: a meta-analysis]

OBJECTIVES

To compare the cardioprotection effect between blood and crystalloid cardioplegia during cardiac surgery in adult patients, and provide a theoretical basis for optimal myocardial protection strategies.

METHODS

A meta-analysis of randomized controlled trials (RCT) studies about comparing blood and crystalloid cardioplegia in adult patients undergoing cardiac surgery were performed. Cochrane library (Issue 3, 2011), MEDLINE, EMBase, PubMed, HighWire, CBM and CNKI were searched from January 1985 to December 2011. Studies were assessed according to the Cochrane Handbook for systematic reviews. Data were extracted from these trials and analyzed by RevMan5.1 software.

RESULTS

Sixteen trials involved 3934 patients were included, 2004 cases were in blood group, and 1930 were in crystalloid group. There was no statistical heterogeneity between studies using a fixed effects model. Meta-analysis indicated that, there were no significant differences between blood and crystalloid group in the incidence of postoperative 30 days mortality (OR = 1.11, 95%CI: 0.59 - 2.08, P = 0.74), the incidence of postoperative low cardiac output (OR = 0.98, 95%CI: 0.41 - 2.33, P = 0.85), the incidence of perioperative myocardial infarctions (OR = 0.85, 95%CI: 0.55 - 1.29, P = 0.44), and inotropic support requirement (OR = 1.05, 95%CI: 0.81 - 1.38, P = 0.70).

CONCLUSION

The blood cardioplegia is no difference with crystalloid cardioplegia in adult patients undergoing cardiac surgery.

Study design for the Immediate Myocardial Metabolic Enhancement During Initial Assessment and Treatment in Emergency Care (IMMEDIATE) Trial: A double-blind randomized controlled trial of intravenous glucose, insulin, and potassium for acute coronary syndromes in emergency medical services

BACKGROUND

Experimental studies suggest that metabolic myocardial support by intravenous (IV) glucose, insulin, and potassium (GIK) reduces ischemia-induced arrhythmias, cardiac arrest, mortality, progression from unstable angina pectoris to acute myocardial infarction (AMI), and myocardial infarction size. However, trials of hospital administration of IV GIK to patients with ST-elevation myocardial infarction (STEMI) have generally not shown favorable effects possibly because of the GIK intervention taking place many hours after ischemic symptom onset. A trial of GIK used in the very first hours of ischemia has been needed, consistent with the timing of benefit seen in experimental studies.

OBJECTIVE

The IMMEDIATE Trial tested whether, if given very early, GIK could have the impact seen in experimental studies. Accordingly, distinct from prior trials, IMMEDIATE tested the impact of GIK (1) in patients with acute coronary syndromes (ACS), rather than only AMI or STEMI, and (2) administered in prehospital emergency medical service settings, rather than later, in hospitals, after emergency department evaluation.

DESIGN

The IMMEDIATE Trial was an emergency medical service-based randomized placebo-controlled clinical effectiveness trial conducted in 13 cities across the United States that enrolled 911 participants. Eligible were patients 30 years or older for whom a paramedic performed a 12-lead electrocardiogram to evaluate chest pain or other symptoms suggestive of ACS for whom electrocardiograph-based acute cardiac ischemia time-insensitive predictive instrument indicated a ≥75% probability of ACS, and/or the thrombolytic predictive instrument indicated the presence of a STEMI, or if local criteria for STEMI notification of receiving hospitals were met. Prehospital IV GIK or placebo was started immediately. Prespecified were the primary end point of progression of ACS to infarction and, as major secondary end points, the composite of cardiac arrest or in-hospital mortality, 30-day mortality, and the composite of cardiac arrest, 30-day mortality, or hospitalization for heart failure. Analyses were planned on an intent-to-treat basis, on a modified intent-to-treat group who were confirmed in emergency departments to have ACS, and for participants presenting with STEMI.

CONCLUSION

The IMMEDIATE Trial tested whether GIK, when administered as early as possible in the course of ACS by paramedics using acute cardiac ischemia time-insensitive predictive instrument and thrombolytic predictive instrument decision support, would reduce progression to AMI, mortality, cardiac arrest, and heart failure. It also tested whether it would provide clinical and pathophysiologic information on GIK's biological mechanisms.

Pig heart preservation with antegrade intracellular crystalloid versus antegrade/retrograde miniplegia

Both histidine-tryptophan-ketoglutarate (HTK) solution and Braile miniplegia are commercially available and used with high success. The objective of this work was to compare the effects of both strategies in an animal model. Twelve pigs were divided into control, HTK, or Braile groups using a model of controlled global cardiac ischemia/reperfusion under cardiopulmonary bypass with 1 hour heart ischemia followed by 2 hour reperfusion. No significant differences were found over time or between groups for heart rate, arrhythmia, number of defibrillations required, blood gases, myocardial lactate production, myocardial oxygen consumption, nor coronary flow index. The Braile strategy was associated with a lower 120 minute postreperfusion coronary vascular resistance with higher water content, leukocyte infiltration, and oxidative damage compared with controls. Drainage of HTK solution to the venous return was followed by higher potassium and lower sodium blood concentrations. One-hour heart preservation with HTK or Braile systems followed by 2 hour reperfusion both allow for acceptable preservation of the healthy pig myocardium. Maneuvers such as leukocyte filtration or hemofiltration may further improve these conditions.

Cardiac and neurological assessment of normothermia/warm blood cardioplegia vs hypothermia/cold crystalloid cardioplegia in pediatric cardiac surgery: insight from a prospective randomized trial

OBJECTIVE

Although normothermia and warm blood cardioplegia are widely used in adults, cold crystalloids and hypothermia remain routinely used in pediatric cardiac surgery. The superiority of either technique in both brain and myocardial protection remains controversial. We designed a prospective randomized study to compare both approaches in terms of early myocardial protection and late neurodevelopmental status.

METHODS

From 2004 to 2005, 47 patients were randomly assigned to either mild hypothermia associated to cold crystalloid cardioplegia (CCC, 22 patients) or normothermia with intermittent warm blood cardioplegia (IWBC, 25 patients). Intramyocyte adenosine triphosphate (ATP) was measured before, during and after cardioplegic arrest and results between groups were compared. In addition to their cardiac status, early and late neurologic assessment was performed by psychometric evaluation tests.

RESULTS

Intracellular ATP levels were not significantly different between the two groups. However, intragroup comparison revealed different profiles according to myocardial protection: in the normothermia/warm blood cardioplegia group, ATP concentration increased during cardioplegic arrest and returned to initial values afterward (11 nmol mg(-1) vs 21 nmol mg(-1) vs 10 nmol mg(-1), p < 0.001), such changes did not occur in the cold protocol (17 nmol mg(-1) vs 19 nmol mg(-1) vs 14 nmol mg(-1), p = NS). Early neurological outcome was similar in both groups. At late follow-up (mean = 4 years), no significant difference was observed between the two groups.

CONCLUSIONS

This study demonstrates that normothermia/IWBC protocols are not deleterious when compared with more conventional approaches. A more physiologic ATP steady state, reflecting the absence of cellular ischemic insult was observed in the IWBC group. Importantly, no significant difference was found between IWBC and CCC groups in terms of early and late neurodevelopmental status.

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.

Exploring at the molecular level the effects of blood and blood-insulin cardioplegias used during open-heart surgeries on myocardial prevention

AIM

The aim of this study was to measure the changes in the levels of soluble adhesion molecules involved in acute inflammation during ischemia-reperfusion in adults who underwent open-heart surgery using blood and blood-insulin cardioplegia and to examine the differences in tissue damage at the molecular level as a consequence of insulin's effect on myocardial energy metabolism.

METHODS

Non diabetic 36 patients were enrolled. Blood cardioplegia was used at all cases; insulin and glucose were added at the study group. Blood samples were taken from the coronary sinus and the radial artery before cross-clamp (T1), at 1st (T2) and 30th(T3) minutes after reperfusion. Soluble intercellular adhesion molecules-1 (sICAM-1), soluble vascular adhesion molecules-1 (sVCAM-1), soluble platelet/endothelial cells adhesion marker-1 (sPECAM-1) and serum lactate levels were measured in these samples. Cardiac enzymes (CK-MB, troponin, and myoglobin) were measured at postoperative 1th, 8th and 16th hours. The total duration of mechanical ventilatory support during postoperative period, and the number of days in the intensive care unit and hospital were recorded.

RESULTS

No significant differences were observed in sVCAM-1 levels in blood taken from the radial artery at T1, T2 and T3 in either group. There were significant increases between T1 and T3 and between T2 and T3 in samples obtained form the coronary sinus (P=0.000 and P=0.003, respectively). Significant increases in sPECAM-1 in samples obtained from both sites between T2 and T3 in both groups (P=0.000) were observed. These differences were similar in both groups. Troponin levels at 8th and 16th hours in the blood-insulin cardioplegia group were higher than the blood cardioplegia group (P=0.003 and P=0.032, respectively).

CONCLUSION

Supplementation of blood cardioplegia with insulin did not yield a significant improvement in adhesion molecules. Therefore, superiority of one cardioplegia over the other in delivering myocardial protection during open-heart surgery has not been shown.

Cardioplegia and diazoxide modulate STAT3 activation and DNA binding

BACKGROUND

Previously, we have shown that magnesium supplemented potassium (DSA) cardioplegia and DSA containing diazoxide (DSA+DZX) significantly decrease apoptosis after ischemia. The mechanism for this enhanced cardioprotection was unknown, but we believed that alterations in signal transducers and activators of transcription (STATs) may play a role. To investigate this hypothesis, we examined the effects of DSA and DSA+DZX cardioplegia on STAT1/3 phosphorylation and DNA binding in the in situ blood perfused pig heart model.

METHODS

Pigs (32 to 42 kg) undergoing total cardiopulmonary bypass underwent left anterior descending coronary artery occlusion for 30 minutes. The aorta was crossclamped and DSA (n = 6) or DSA+DZX (n = 6) cardioplegia was administered, followed by 30 minutes of global ischemia and 120 minutes of reperfusion. Control hearts (n = 3) received cardiopulmonary bypass and sham reperfusion only. Tissue samples from regional and global ischemia zones were harvested and used for Western blot and electrophoretic mobility shift assay.

RESULTS

Regional and global ischemia significantly increase proapoptotic STAT1 tyrosine phosphorylation. This increase is significantly greater in the regional as compared with the global ischemia zone. Tyrosine phosphorylation of antiapoptotic STAT3 is increased in the global ischemic zone but is significantly decreased in the regional ischemic zone and is associated with increased apoptosis. The DSA+DZX significantly increases tyrosine phosphorylation of antiapoptotic STAT3 and DNA binding in the regional ischemia zone and significantly decreases apoptosis.

CONCLUSIONS

The addition of diazoxide to DSA cardioplegia significantly decreases apoptosis by significantly increasing tyrosine phosphorylation of STAT3 and its DNA binding and represents an additional modality for enhancing myocardial protection.

[Strategy and perspective of myocardial protection during ischaemia and reperfusion, and the role of volatile anaesthetics]

Surgical coronary revascularization is based on effectiveness of cardioplegia directed to protect myocardial functional integrity during periods of ischaemia and reperfusion. The aim of cardioplegia is to protect numerous intracellular processes: to spare the intracellular energy stores, to reduce free oxygen radical synthesis, to protect the function of the endothelium and myocardial oxygen balance as well as ionic balance. Crystalloid or blood cardioplegia, with anterograde or retrograde infusion, is a basic procedure of the intraoperative cardiac protection. Glucose-insulin-potassium (GIK) solution was primarily used in myocardial infarction. After the first promising results, some surgical teams started using a high glucose-insulin-potassium solution, as a metabolic modulation approach, during coronary surgery in addition to cardioplegia.The improvement of the left ventricular performances, rare rhythm disturbances and reduced need for inotropic support during the period of reperfusion justified the GIK beneficial effect. Further improvement in metabolic modulation during coronary surgery was made with fluorine ion halogenated volatile aneasthetics used for anaesthesia. Results of some experimental and first clinical studies have induced a new approach to modulation of the intracellular metabolic mechanisms and announced the new concept of anaesthetic preconditioning in coronary surgery. Large, randomized studies are needed to evaluate anaesthetic preconditioning and dependence of its efficiency on the type and dose of volatile anaesthetics.

A peroxynitrite decomposition catalyst: FeTPPS confers cardioprotection during reperfusion after cardioplegic arrest in a working isolated rat heart model

Heart transplant is considered to be an extremely severe ischemia-reperfusion sequence. Post-ischemic dysfunction triggers multiple processes especially oxidative stress, but the mechanisms remain unclear. Free radical interactions lead to peroxynitrite generation, which seems to be involved in early post-transplant heart failure. The aim of this study was to evaluate the potential impact of a peroxynitrite decomposition catalyst: FeTPPS (5,10,15,20-tetrakis-[4-sulfonatophenyl]-porphyrinato-fer[III]) and pyruvate on myocardial functional recovery after cardioplegic arrest using an experimental protocol in rat hearts. Isolated working rat hearts were subjected to ischemia (4 h at 4 degrees C in cardioplegic solutions), followed by 45 min of reperfusion. Four groups were constituted: control, pyruvate: (2 mm) added to cardioplegic and Ringer-lactate solutions, FeTPPS: (10 microm) perfused during the reperfusion, and a combination of both treatments. Lactate dehydrogenase (LDH) activity was assessed during the reperfusion to evaluate the level of cardiac injury. Oxidative stress was evaluated on heart slices using a fluorescent probe: dihydroethidium, and the collagen content was assessed using picro-Sirius coloration. Global post-ischemic recovery in the control group was about 35% of pre-ischemic values. Results showed that addition of pyruvate led to an increase in myocardial function and to a decrease in LDH activity released during the reperfusion. FeTPPS protected against injury after cardioplegic arrest during reperfusion. No additive effect of the two treatments (pyruvate + FeTPPS) was observed. The collagen content was better preserved in the FeTPPS group than in the control and pyruvate groups. In conclusion, this study shows that peroxynitrite plays an important role in the functional and cellular alterations associated with cardiac ischemia-reperfusion sequences and confirms that pyruvate helped to preserve myocardial function. The use of the peroxynitrite decomposition catalyst (FeTPPS) may help to improve myocardial preservation during a prolonged ischemia sequence.

Advances in coronary heart disease surgery in Latin America

BACKGROUND

The beginnings of coronary artery bypass graft in Latin America could be set in the year 1971. Since then, improvements in technique and greater experience have resulted in a rapid increase in the rate of interventions performed in the region.

METHODS AND RESULTS

Searches through PubMed and Literatura Latinoamericana y del Caribe en Ciencias de la Salud, as well as personal communications from specialists from Latin America, have been the source of information. Articles were selected by their content related to the theme, and the authors' nationality and information is mainly from Latin America. Demographic information of the population of Latin America denotes higher age averages, and this implies an increase in the severity of comorbidities in patients who undergo surgery. Longer life expectancy and improvements in medical therapy have implied that patients survive a first intervention beyond the expected time a bypass persists patent. Wall vessel properties of arterial conduits, plus a better anastomotic technique, seem to be the current solution to worsening in the coronary health of patients who undergo revascularization surgery in Latin America.

CONCLUSIONS

Despite scarce economic investment in medical sciences, many academic groups contribute to the exploration of therapeutic pharmacological combinations and inclusively apply genetic strategies.

Induction of cardioplegic arrest immediately activates the myocardial apoptosis signal pathway

Myocardial ischemia-reperfusion, including cardioplegic arrest (CA), has been associated with cardiac apoptosis induction. However, the time course of apoptosis activation and the trigger mechanisms are still unclear. Because apoptosis inhibition may represent a novel therapeutic strategy for long-term myocardial preservation, we sought to investigate the time course of apoptosis signal-pathway induction during CA. As to method, Sprague-Dawley rats (300–350 g) were anesthetized, intubated, and mechanically ventilated. CA was initiated by infusion of ice-cold crystalloid solution (Custodiol, 10 ml/kg) into the aortic root, and hearts were rapidly excised and stored for 0, 30, 60, and 120 min in 0.9% sodium chloride solution (28°C). In controls, no CA was initiated before removal and storage at 28°C. In another group, calcium-rich cardioplegia was used, and an additional group received a caspase-8 inhibitor before CA induction. Left ventricular cytosolic extracts were isolated and investigated for the activity of caspase-3 and -6 (effector caspases) and caspase-8 and -9 (involved in extrinsic and intrinsic pathways of apoptosis induction). Fluorometric activity assays were performed by using specific substrates. As a result, activities of all tested caspases were significantly increased immediately after CA induction compared with controls. Administration of the caspase-8 inhibitor significantly reduced activities of all caspases. With calcium-rich cardioplegia, caspase activities were significantly lower compared with low-calcium CA. Control hearts also showed an increase of caspase activities during cold-storage ischemia without CA but had significantly different time courses compared with hearts with CA. In conclusion, our data show rapid apoptosis signal-pathway induction immediately following CA exposure. Thus apoptosis signal-pathway inhibition as a potential strategy for improved myocardial preservation would have the greatest effect when applied before CA exposure.

Influence of two different types of cardioplegia on hemodilution during and after cardiopulmonary bypass, postoperative chest-drainage bleeding and consumption of donor blood products

The aim of this study is to compare the effects of colloidal cardioplegia and blood cardioplegia in patients who underwent cardiac surgical procedures with cardiopulmonary bypass, and to evaluate their influence on hemodilution, bleeding and consumption of donor blood products in a retrospective clinical study. 100 male patients who underwent cardiac surgical procedure were divided into two groups: 50 patients were administered intermittent normotherm or mild hypotherm (34 degrees C) Calafiore blood cardioplegia with potassium chloride 14,9%; 50 patients were administered one initial doses of cold Kirsch - solution followed from intermittent cold colloidal cardioplegia using hydroxyethyl starch (HES 450/0,7). Hemoglobin values after the first dose of cardioplegia were significantly lower in the HES-group than in the Calafiore- group). After the first dose of cardioplegia platelets count was lower in the HES-group than in the Calafiore-group. Hemoglobin and hematocrit values 24h postoperative were lower in the HES-group than in the Calafiore-group. There was no difference in chest-drainage bleeding 12h and 24h postoperative between the groups. The consumption of donor erythrocyte concentrate and fresh frozen plasma was significantly higher in the HES-than in the Calafiore- group. The choice of either colloidal or blood cardioplegia does not influence the postoperative chest-drainage bleeding. The results suggest that high molecular colloidal cardioplegia with HES-solution is associated with higher hemodilution during and after cardiopulmonary bypass and significantly increases the consumption of donor blood products.

Occluding the junction of the middle cardiac vein in retrograde cardioplegia: a new retrograde cannula for optimizing retrograde cardioplegic delivery

Retrograde cardioplegia often fails to provide adequate perfusion of the right ventricle and the posterior wall of the left ventricle because of the shunt through the thebesian vein. However, much of the retrograde cardioplegic solution may leak into the right atrium after veno-venous anastomoses at the apex of the heart, especially when a retrograde balloon cannula is inserted too deeply in the great cardiac vein, although this is not widely recognized. We designed a new retrograde cardioplegic cannula with three self-inflating balloons, which reduced the shunt flow by occluding the junction of the middle cardiac vein and improving in cardioplegic delivery. We describe the myocardial dye distribution achieved by using this new cannula in pig hearts and report the results of its clinical application.

Normothermic bypass in pediatric surgery: technical aspect and clinical experience with 1400 cases

We analyzed our experience with warm perfusion and blood cardioplegia in pediatric surgery. Warm surgery was performed in 1400 patients. Prime and perfusate are kept at 37 degrees C before and during bypass and intermittent warm blood cardioplegia is used for myocardial protection. Analyzed parameters were: perioperative blood gas, hydric balance of cardioplegia, spontaneous resumption of rhythm after aortic unclamping, troponin I level, postoperative neurologic and renal function, duration of mechanical ventilation (five diagnostic groups), and duration of intensive care unit (ICU) stay. Satisfactory gas exchange is the rule, and fluid addition is negligible during warm cardioplegia. Spontaneous resumption of sinus rhythm occurred in 99% of patients, Troponin I elevation was < 10 ng/ml in 46% of cases. Prevalence of neurologic complications (0.3%) and of renal insufficiency treated by peritoneal dialysis (0.35%) favorably compares with data reported in the literature. Average mechanical ventilation time was < 48 hours in each diagnostic group. Duration of ICU stay was < 48 hours in 86% of the 1400 patients. In our experience, normothermic surgery is an excellent alternative to hypothermia.

A simple and reliable method to assess heart viability after hypothermic procurement

Hearts from brain dead pigs (n = 18) were submitted to 0 (group I), 10 (group II), or 20 (group III) minutes of in situ warm ischemia (animal exsanguination). After harvesting, cold cardioplegia solution was perfused in retrograde fashion and initial coronary flow (ICF) measured. After left ventricular energetic indices were measured using NMR spectroscopy, the hearts were transplanted orthotopically. Follow-up was performed over 120 minutes after cardiopulmonary bypass. We observed a progressive decrease in ICF with increased warm ischemia times: 50 +/- 3.4 mL/min per 100 g of tissue in the group I, 36 +/- 7 and 30 +/- 3.5 in groups II and III, respectively (P < .05 and P < .01 versus group I). The ICF strongly correlated with the energetic index (r = 0.76, P < .001) and with posttransplant function of the transplanted heart. These data showed that measurement of initial coronary flow after cardioplegia was a reliable test to evaluate cardiac graft viability before transplantation.

[Glucose-insulin-potassium (GIK) solution: cardioprotective effects of insulin]

In the Anesthesiology Department of the Instituto Nacional de Cardiología The medical staff uses the glucose insulin potassium i.v. for myocardial protection. The energy is dereived from lipidic beta oxidation, glucose breakdown and amino acid catabolism in mitochondria. In myocardial ischemia, from de aortic cross clamping, the metabolic myocardial substrates diminished as well as the energy produced by adenosine (ATP). During myocardial ischemia, an increase in long chain lipids emhances mitochondrial permeability, promotes depletion of citochrome C and lost of the capability of transmembrane regulation. In the hipoperfused myocardium, by coronary vasoconstriction, short chain fatty acids oxidation predominates, if fatty metabolism during reperfusion is elevated. More of them will enter [IBM1] the Krebs cycle and, as a consequence, less energy will be produced. The glucose-insulin-potassium solution provides the glucose needed by the myocardium in reperfusion conditions and protects the cellular membrane's integrity as well as pumps and ionic channels, it allows maintaining the action potential probably because ATP-depended channels block and prevent potassium loss, it reduces the cytosol calcium overload and prevent cardiac arrhythmias, preserves the sodium ATPasa pump avoiding the rise in cytosolic sodium; glucose prevents the production of free oxygen radicals. Fatty acids, during ischemia, are responsible for the metabolism and elevation of enzymes, such as acilcarnitine and acylcoenzime-A, which promote intracellular calcium overload and arrhythmias. The insulin has anti-inflammatory effects and anti-apoptoic effects. When blood glucose is controlled during the perioperative period the mortality is reduced.

Comparative study of donor lung injury in heart-beating versus non-heart-beating donors☆☆☆

OBJECTIVE

The use of non-heart-beating donors (NHBD) has been advocated as an alternative to overcome the critical organ shortage in lung transplantation despite the warm ischemic period that may result in primary graft dysfunction. On the contrary, brain death in the heart-beating donor (HBD) may be an underestimated risk factor for donor lung injury. We postulated that 60 min of warm ischemia in the NHBD is less detrimental to the lung than the pathophysiological changes after brain death in the HBD. In this study we compared the quality of lungs from HBD versus NHBD in an isolated reperfusion model.

METHODS

Pigs (n=10 per group) were divided into three groups. In group I (HBD), brain death was induced by acute inflation of an intracranial epidural balloon catheter. In group II (CONTROL), the balloon was not inflated. In group III (NHBD), cardiac arrest was induced by myocardial fibrillation. After 5 h of in situ mechanical ventilation, lungs in HBD and CONTROL were preserved with a cold antegrade flush. In NHBD, unflushed grafts were explanted after 1 h of warm ischemia and 4 h of topical cooling in the cadaver. Graft performance was evaluated during 1 h in an isolated ventilation and reperfusion model. Extravascular lung water content (EVLW) was calculated. All data are reported as mean+/-SEM.

RESULTS

A significant autonomic storm was observed in HBD following balloon inflation. During ex vivo assessment, pulmonary vascular resistance (PVR) at 60 min in HBD (2634+/-371 dynes cm(-5)) was significantly higher as compared with that of CONTROL and NHBD (1894+/-137 dynes s cm(-5) and 1268+/-111 dynes s cm(-5), respectively; p<0.05). Plateau airway pressure (Plateau AwP) was also higher in HBD (17+/-1cmH2O) compared with that of CONTROL (12+/-1 cmH2O; p<0.05) and NHBD (14+/-1 cmH2O; not significant). No significant differences were observed between HBD, CONTROL and NHBD in EVLW (79+/-1%, 79+/-0% and 78+/-1%, respectively), and in PO2/FiO2 (564+/-58 mmHg, 622+/-14 mmHg and 578+/-26 mmHg, respectively).

CONCLUSIONS

These data indicate that 1-h warm ischemic lungs in our model are less susceptible to ischemia-reperfusion injury than lungs retrieved 5 h after brain death. This study further supports the use of lungs from NHBD for pulmonary transplantation.

Evaluation of myocardial metabolism with microdialysis during bypass surgery with cold blood- or Calafiore cardioplegia

BACKGROUND

For the first time, microdialysis was used to investigate in vivo and online the myocardial metabolism during and after cardiac surgery in patients treated with two different methods of myocardial protection.

METHODS

Thirty patients underwent standard CABG with one of two different methods of myocardial protection. The patients were randomised to receive either cold blood (COLD group) or warm modified Calafiore cardioplegia (WARM group). Microdialysis probes were implanted into the myocardium of left ventricular apical region of the heart. Cardioplegia was given antegrade only. Microdialysis measurements were performed at time intervals before, during and 24 h after cardiopulmonary bypass and analysed for glucose, lactate, pyruvate and glycerol.

RESULTS

Myocardial lactate concentrations were significantly higher in the WARM group compared with that of the COLD group, while serum lactate was comparable. Glycerol was significantly higher at the end of the clamping time in the WARM group. At the same time the glucose-lactate ratio as a marker of nutritional disorder had significantly lower levels in the WARM group. The cumulative CK-MB release over 24 h was significantly higher in those hearts protected with warm blood.

CONCLUSIONS

The oxidative stress measured was significantly higher in patients undergoing CABG using modified Calafiore cardioplegia, whereas the cold cardioplegia minimised the effects of aortic clamping. The results indicate that cold cardioplegia offers superior protection of the heart, in terms of more rapid normalisation of myocardial metabolism. In elective myocardial revascularisation, intermittent antegrade warm blood cardioplegia is a comparable safe method of myocardial protection. However, in patients referring to a long clamping time, advantages of cold cardioplegia for myocardial revascularisation may be magnified.

Effect of Combining Phosphodiesterase III Inhibitors With St Thomas Hospital’s Solution Used as Transplantation Preservative Solution in Isolated Rat Hearts

Improved preservation of the harvested heart with attenuation of the reperfusion injury is important for successful outcomes of cardiac transplantations. The most commonly used cardioplegic solution, to prevent ischemic changes has been St Thomas' Hospital cardioplegic solution (STHCS). However, it is neither ideal nor sufficient to prevent myocardial ischemia and reperfusion injury. Phosphodiesterase inhibitors can attenuate the damage due to the injuries of ischemia and reperfusion. In this study we sought to enrich STHCS with a phosphodiesterase inhibitor to improve preservation of cardiac functions. The harvested hearts of 24 rats were divided into four groups. All hearts were mounted on a Langendorff perfusion system. After a stabilization period, cardiac arrest was maintained by STHCS. The hearts were stored in STHCS alone or with milrinone, amrinone, or enoximone for 6 hours. The reperfusion was maintained using a modified Tyrode's solution. All hearts were compared for their preischemic and postischemic left ventricular developed pressure, +dp/dtmax, -dp/dtmax, duration of systole, ejection time, and time to reach peak systolic pressure. Coronary effluent was collected for lactate dehydrogenase (LDH) measurements. The initial values for all metrics were comparable between the groups. During the postreperfusion period, all hearts showed lower peak systolic pressures than the initial values. Although the amrinone group seemed to have higher values, the 25-minute result was at the border of significance and the 30-minute value, significantly higher. All hearts showed far lower results of maximum changes in contractility during the time period (+dp/dtmax) versus the initial values; comparisons between groups were not significant. For the parameter of maximum changes in relaxation during the time period (-dp/dtmax), while other hearts showed lower results, the amrinone group displayed values comparable to the initial ones after 20 minutes. Comparisons between groups were insignificant. While other hearts had comparable values for time of systole, the hearts applied with milrinone reached these values after 15 minutes. Group comparison for time of ejection revealed that the results at 5-minute postreperfusion were higher in the enoximone and the amrinone groups than the milrinone group. Postreperfusion 5-minute results were higher in the enoximone and the amrinone groups than the milrinone group for time to reach peak systolic pressure. LDH levels were lowest in the amrinone group. In conclusion, our study revealed that adding phosphodiesterase inhibitors to STHCS improved peak systolic pressure and maximum changes in relaxation during the time period (-dp/dtmax, mm Hg/s). It also decreased the LDH leakage, which corresponded to the degree of ischemic tissue damage. Amrinone seemed to result in more favorable results, which may be attributed to its additional effects on inflammation, including those on cytokines and leukocyte aggregation.

Effect of Hypoxia-Reoxygenation on Endothelial Function in Porcine Cardiac Microveins

BACKGROUND

The cardiac venous system possesses up to 30% of total coronary vascular resistance and the effect of hypoxia-reoxygenation (H-R) and St Thomas (ST) cardioplegic solution on the vein is unknown. We investigated the effects of H-R, with or without ST, on endothelium-derived hyperpolarizing factor (EDHF)-mediated relaxation in porcine cardiac microveins under clinically relevant temperatures.

METHODS

The microveins (diameter 200 to 450 microM) mounted in a myograph were subjected to hypoxia (Po2 < 5 mm Hg) for 30 minutes in Krebs solution (n = 8) or for 60 minutes in Krebs (n = 8) or in ST at 37 degrees C (n = 8) or 4 degrees C (n = 8), followed by 30-minute reoxygenation. The microvein was precontracted with thromboxane A2 mimetic U46619 (-7 log M) and the EDHF-mediated relaxation was induced by bradykinin (-10 to -6 log M) in the presence of indomethacin, NG-nitro-L-arginine, and oxyhemoglobin before and after H-R.

RESULTS

The maximal EDHF-mediated relaxation was significantly reduced after 30-minute hypoxia (38.7 +/- 2.0% vs 61.1 +/- 2.3%, n = 8, p < 0.001) or 60-minute hypoxia in either Krebs or ST at 37 degrees C (Krebs: 27.8 +/- 1.2% vs 56.6 +/- 2.5%, n = 8, p < 0.001; ST: 23.8 +/- 4.1% vs 57.1 +/- 1.5%, n = 8, p < 0.001). The relaxation was significantly less after prolonged H-R in Krebs (p < 0.001). Incubation in Krebs or ST at 4 degrees C also reduced the EDHF-mediated relaxation (Krebs: 25.3 +/- 3.3%, n = 8, p < 0.001; ST: 29.1 +/- 4.4%, n = 8, p < 0.001) and there were no significant differences between Krebs and ST regarding the relaxation at either 37 degrees C or 4 degrees C (p > 0.05).

CONCLUSIONS

We conclude that (1) H-R impairs EDHF-mediated relaxation in the coronary microveins with more severe injury during prolonged H-R and (2) ST does not provide protection to the EDHF-mediated relaxation impaired by H-R at either 37 degrees C or 4 degrees C.

Myocardial protection during neonatal cardiac surgery

Myocardial protection is of major concern in neonatal cardiac surgery where coronary ostial transfer is required as part of the surgical procedure. Retrograde coronary sinus perfusion (RCSP) of cold cardioplegic solution was evaluated in infants undergoing arterial switch operations. Hemodynamic measurements and postoperative cardiac troponin I (cTnI) levels were estimated in addition to transthoracic echocardiography to assess the extent of myocardial injury. The results were compared with a similar cohort of patients where ante grade selective coronary artery perfusion (ASCP) was used during coronary ostial transfer. Our experience suggests that RCSP is a useful option in this subset of patients.

[Antegrade warm blood cardioplegia compared to crystalloid cardioplegia in myocardial protection]

The tehniques of myocardial protection in cardiac surgery are innumerable. In this trial we tried to compare two established cardioplegic strategies in elective on-pump surgery (Intermittent antegrade warm blood cardioplegia--Calafiore--) and Kirsch-Solution with Haes). We took the data from our medical documentaton for 115 patients who underwent elective on-pump surgery in time period from February 2005 to July 2005.

[Protective effects of polarizing cardioplegia with Na(+) channel inhibitor in ex vivo rat heart preservation]

OBJECTIVE

To investigate the protective effects of polarizing cardioplegia with Na(+) channel inhibitor tetrodotoxin (TTX) in ex vivo rat heart preservation.

METHODS

Using a Langendorff preparation, Wistar rat hearts were arrested and preserved with St. Thomas (STH) solution (n=10) or with polarizing cardioplegia (TTX, n=10) for 7 h in hypothermic storage (10 degrees Celsius). All the hearts then underwent 30 min of reperfusion. Pre-ischemia and post-ischemia indexes of the rat hearts were determined, including the hemodynamic parameters, myocardial enzymology, ATP content and ultrastructural changes.

RESULTS

The recovery of hemodynamic parameters of the hearts in TTX group were better than those in STH group (P<0.01). In comparison with STH group, the leakage of creatine kinase (CK) and lactate dehydrogenase (LDH) in TTX group was significantly lower (P<0.05) and ATP level maintained a relative high level with better protected myocardial ultrastructure.

CONCLUSION

TTX polarizing cardioplegia provides more effective long-term hypothermic preservation of isolated rat hearts than STH.