Cardioplegia and myocardial protection: time for a reassessment?

Redosing of long acting cardioplegic solutions in adult cardiac surgery: A comparative study

INTRODUCTION

Despite promising results regarding using long-acting cardioplegia in the adult population, little data exists specifically for operations requiring prolonged aortic cross-clamp needing additional doses. In this pilot study, we evaluated the outcomes of patients undergoing surgery with prolonged cross-clamp time based on four different redosing compositions.

METHODS

During the period from January 2019 until June 2022, 288 patients undergoing cardiac surgery with an expected cross-clamp time over 60 min were prospectively randomized regarding the type of the cardioplegia used: Group 1 (N = 150)- single-dose del Nido antegrade cardioplegia and Group 2 (N = 138)- single-dose Histidine-Tryptophane-Ketoglutarate (HTK) antegrade cardioplegia. In patients with ischemic time over 60 min, needing a redosing were further analyzed separately in four subgroups: (A) Cold whole blood (CWB) (4:1) (N = 95); (A1: DN-CWB; A2: HTK-CWB) and (B) St Thomas Solution (N = 92) (B1: DN-St Thomas; B2: HTK-St Thomas. Control groups were C1 (DN redosed by DN) and C2 (HTK by HTK).

RESULTS

Troponin levels in A1 and B1 groups were significantly lower than in DN-control. Respiratory support time and incidence of atrial fibrillation were significantly lower in Group A1 versus DN-control.

CONCLUSIONS

Long-acting cardioplegic techniques are becoming widely utilized in the adult population, with minimal data on redosing methods/compositions for prolonged cases. Due to the small patient population, further investigation is needed to delineate optimal redosing methods, but this report brings to attention the initial success of multiple strategies.

Predictors of aortic clamp time duration and intensive care unit length of stay in elective adult cardiac surgery

Background

Aortic cross-clamp utilized during cardiac surgery facilitates motionless and bloodless surgical field. However, the duration of clamp time has an inverse effect on early post-operative recovery period. In this study, we sought to examine the predictors of aortic clamp duration and intensive care unit length of stay.

Results

Six hundred and nine adult patients presented for elective cardiac surgery between December 2019 and December 2020 were enrolled. The age of patients ranged from 18 to 82 years (mean 55.62 years, SD ± 12.3 years). Male/female ratio is 4.6:1. Most patients (87.2%) were planned for coronary artery bypass grafting (CABG) and 78 patients (12.8%) for single heart valve procedure. Operative time (OT) ranged from 120 to 402 min and averaged 259.4 min (SD ± 45.9 min). ACC time ranged from 15 to 159 min and averaged 50.56 min (SD ± 19.4 min). Factors associated with significantly longer ACCT were: smoking (OR = 1.89 (95% CI 1.3–2.74), p value = 0.01), respiratory disease (OR = 0.48 (95% CI 0.24–0.96), p value = 0.039), obesity (OR = 1.76 (95% CI 1.18–2.63), p value = 0.005) and AVR (OR = 2.11 (95% CI 1.17–3.83), p value = 0.013). Low cardiac output syndrome (LCOS) was observed in 19.2% of patients. Longer than average ACCT was associated with increased use of inotropes (p value < 0.001), intra-aortic balloon pump (p value < 0.001) and first 24 h post-operative blood loss (p value < 0.001). The average intensive care unit length of stay (ICULOS) was 1.64 days (SD ± 1.1 days). Patients' ACCT converged positively and significantly on ICULOS (Beta coefficient = 1.013 (95% CI 1.01–1.015), p value < 0.001).

Conclusion

Aortic cross-clamping is a crucial method in cardiac surgery to achieve motionless field; however, prolongation of this method had an incremental risks for the development of low cardiac output syndrome, increased first 24 h post-operative blood loss and longer stay in the intensive care unit.

Supplementary Information

The online version contains supplementary material available at 10.1186/s43044-021-00195-0.

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 Effects of Single-Dose Cardioplegic Solutions Especially in Repeated Doses During Minimally Invasive Aortic Valve Surgery

OBJECTIVE

This study aims to compare del Nido cardioplegia (DNC) and histidine-tryptophan-ketoglutarate (HTK) cardioplegic solutions in minimally invasive aortic valve replacement (mini-AVR) surgery to discuss the safety level of myocardial protection and rationale for redosing intervals.

METHODS

During the period from January 2017 to June 2019, 200 patients undergoing mini-AVR (solely or with concomitant procedures) were prospectively randomized to DNC (n = 100) andHTK (n = 100), both up to 90 minutes ischemic time. Patients with ischemic time over 90 minutes, needing a redosing, were further analyzed in 2 subgroups with DNC-R (n = 30) and HTK-R (n = 36). Sensitive biomarkers, in addition to routine biochemistry, were also documented at baseline (T1), after cessation of cardiopulmonary bypass (T2), and on the first postoperative day (T3). Transmural myocardial biopsies were sampled for staining.

RESULTS

No statistical differences could be demonstrated in DNC and HTK groups with up to 90 minutes cross-clamp times in routine biochemical measurements and basic perioperative clinical outcomes. DNC-R showed significantly more arrhythmia/AV block incidence resulting in more extended intensive care unit (ICU) stay. Interleukin-6 and syndecan-1 in DNC and DNC-R groups were substantially higher at T2. Aquaporin-4 levels were significantly lower in the DNC-R group, demonstrating unsatisfactory response of cells to an excessive volume at T2.

CONCLUSIONS

DNC and HTK provided acceptable myocardial protection as single-dose applications. DNC-R had significantly unbalanced levels of biomarkers, and more arrhythmia/AV block incidence resulting in more extended ICU stay. For patients who may need redosing HTK may be preferable to DNC.

Clinical outcomes of single-dose cardioplegia in high-risk coronary bypass

BACKGROUND

Despite the increasing popularity of single-dose cardioplegia techniques in coronary artery bypass grafting, the time window for successful reperfusion remains unclear. This study aimed to compare different cardioplegic techniques based on early and 30-day clinical outcomes via thorough monitoring.

METHODS

This prospective cohort study included high-risk patients undergoing coronary artery bypass grafting and receiving 3 different types of cardioplegia between January 2017 and June 2019. Group 1 (n = 101) had a single dose of del Nido cardioplegia, group 2 (n = 92) had a single dose of histidine-tryptophane-ketoglutarate, and group 3 (n = 119) had cold blood cardioplegia. Patients were examined perioperatively by memory loop recording and auto-triggered memory loop recording for 30 days, with documentation of predefined events.

RESULTS

Interleukin-6 and cardiac troponin levels in group 1 were significantly higher than those in groups 2 and 3. The incidence of predefined events as markers of inadequate myocardial protection was significantly higher group 1, with more frequent atrial fibrillation attacks and more hospital readmissions. The readmission rate was 17.6% in group 1, 9% in group 2, and 8% in group 3.

CONCLUSIONS

Our data demonstrate the long-term efficacy of cardioplegic techniques, which may become more crucial in high-risk patients who genuinely have a chance to benefit from adjunct myocardial protection. Patients given del Nido cardioplegia had a significantly more prominent inflammatory response and higher troponin levels after cardiopulmonary bypass. This group had issues in the longer term with significantly more cardiac events and a higher rehospitalization rate.

Myocardial protection in cardiac surgery: how limited are the options? A comprehensive literature review

For patients undergoing cardiopulmonary bypass, myocardial protection is a key for successful recovery and improved outcomes following cardiac surgery that requires cardiac arrest. Different solutions, components and modes of delivery have evolved over the last few decades to optimise myocardial protection. These include cold and warm and blood and crystalloid solution through antegrade, retrograde or combined cardioplegia delivery approach. However, each method has its own advantages and disadvantages, posing a challenge to establish a gold-standard cardioplegic solution with an optimised mode of delivery for enhanced myocardial protection during cardiac surgery. The aim of this review is to provide a brief history of the development of cardioplegia, explain the electrophysiological concepts behind myocardial protection in cardioplegia, analyse the current literature and summarise existing evidence that warrants the use of varying cardioplegic techniques. We provide a comprehensive and comparative overview of the effectiveness of each technique in achieving optimal cardioprotection and propose novel techniques for optimising myocardial protection in the future.