The short-term and long-term effects of warm or tepid cardioplegia

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.

Warm Blood Cardioplegia for Myocardial Protection: Concepts and Controversies

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

Rationale for Implementation of Warm Cardiac Surgery in Pediatrics

Cardiac surgery was developed thanks to the introduction of hypothermia and cardiopulmonary bypass in the early 1950s. The deep hypothermia protective effect has been essential to circulatory arrest complex cases repair. During the early times of open-heart surgery, a major concern was to decrease mortality and to improve short-term outcomes. Both mortality and morbidity dramatically decreased over a few decades. As a consequence, the drawbacks of deep hypothermia, with or without circulatory arrest, became more and more apparent. The limitation of hypothermia was particularly evident for the brain and regional perfusion was introduced as a response to this problem. Despite a gain in popularity, the results of regional perfusion were not fully convincing. In the 1990s, warm surgery was introduced in adults and proved to be safe and reliable. This option eliminates the deleterious effect of ischemia-reperfusion injuries through a continuous, systemic coronary perfusion with warm oxygenated blood. Intermittent warm blood cardioplegia was introduced later, with impressive results. We were convinced by the easiness, safety, and efficiency of warm surgery and shifted to warm pediatric surgery in a two-step program. This article outlines the limitations of hypothermic protection and the basic reasons that led us to implement pediatric warm surgery. After tens of thousands of cases performed across several centers, this reproducible technique proved a valuable alternative to hypothermic surgery.

Cardioprotection: a review of current practice in global ischemia and future translational perspective

The idea of protecting the heart from ischemic insult during heart surgery to allow elective cardiac arrest is as old as the idea of cardiac surgery itself. The current gold standard in clinical routine is a high potassium regimen added either to crystalloid or blood cardioplegic solutions inducing depolarized arrest. Ongoing patient demographic changes with increasingly older, comorbidly ill patients and increasing case complexity with increasingly structurally abnormal hearts as morphological correlate paired with evolutions in pediatric cardiac surgery allowing more complex procedures than ever before redefine requirements for cardioprotection. Many, in part adversarial, regimens to protect the myocardium from ischemic insults have entered clinical routine; however, functional recovery of the heart is still often impaired due to perfusion injury. Myocardial reperfusion damage is a key determinant of postoperative organ functional recovery, morbidity, and mortality in adult and pediatric patients. There is a discrepancy between what current protective strategies are capable of and what they are expected to do in a rapidly changing cardiac surgery community. An increased understanding of the molecular players of ischemia reperfusion injury offers potential seeds for new cardioprotective regimens and may further displace boundaries of what is technically feasible.

Decreased incidence of low output syndrome with a switch from tepid to cold continuous minimally diluted blood cardioplegia in isolated coronary artery bypass grafting

OBJECTIVES

The optimal temperature for blood cardioplegia remains unclear.

METHODS

A retrospective analysis was performed on 138 patients undergoing isolated myocardial revascularization by a single surgeon in our institution over a period of 2 years. Patients operated on early in the study period received tepid (29°C) continuous minimally diluted blood cardioplegia (minicardioplegia), delivered in an antegrade continuous fashion. Later, our surgeon began using cold (7°C) blood minicardioplegia in all patients. Data pertaining to clinical outcomes and postoperative biochemical data were obtained, and the two groups were compared.

RESULTS

Low cardiac output syndrome, defined as the need for intra-aortic balloon pump counter pulsation or inotropic medication for haemodynamic instability, was more frequent in the tepid cardioplegia group than in the cold cardioplegia group (16.0 vs 2.4%, P = 0.006). There was no difference in the maximal serum creatine kinase MB between the two groups (cold 25.4 ± 3.21 μg/ml vs tepid 36.5 ± 7.10 μg/ml, P = 0.62), in the rates of perioperative myocardial infarction (cold 1.2% vs tepid 6.0%, P = 0.15) and the need for postoperative insertion of an intra-aortic balloon pump (cold 4.8% vs tepid 0.0%, P = 0.3). There was no other statistically significant difference between the two groups in the measured parameters.

CONCLUSIONS

A higher rate of low cardiac output syndrome in the tepid cardioplegia group suggests inferior myocardial protection with the tepid cardioplegia. Cold cardioplegia may provide better protection than tepid cardioplegia when minicardioplegia is used.

The effect of tepid amino acid-enriched induction cardioplegia on the outcome of infants undergoing cardiac surgery

Background:

Despite promising experimental results, no information has been published on the clinical effects of amino acid-enriched induction cardioplegic solution on outcome in children undergoing cardiac surgery.

Methods:

This is a retrospective study of 185 consecutive patients younger than 12 months with one of the following defects undergoing open heart surgery: atrioventricular septal defect, transposition of the great arteries, tetralogy of Fallot or ventricular septal defect. Patients were divided into two groups according to the following myocardial protection approaches: tepid substrate-enriched induction cardioplegia followed by cold blood cardioplegia (n=113) or only cold blood induction cardioplegia (n=72). Patient allocation was determined by the anesthesiologist in charge of cardiopulmonary bypass (CPB). The primary outcome measure was postoperative myocardial injury assessed by troponin T level and inotrope score.

Results:

Demographic data were similar for both groups. Cardioplegic induction had no overall effect for inotrope score (16.3 ± 9.2 vs.17.9 ± 10.0, p=0.276) or lactate release (1.8 ± 1.3 vs. 1.6 ± 0.8, p=0.110) on arrival to the paediatric intensive care unit. On the first postoperative day, there were no significant differences between the cardioplegia groups for inotrope score (13.7 ± 8.7 vs.14.3 ± 9.1, p=0.657), troponin T (2.4 ± 1.6 vs. 2.8 ± 2.7 μg/L, p=0.267), lactate (1.5 ± 2.0 vs. 1.5 ± 0.8, p=0.972), or any of the other clinical outcome measures.

Conclusions:

Compared to cold cardioplegia alone, the administration of tepid induction cardioplegia had no effect on the clinical outcome of infants who underwent cardiac surgery.

Is cold or warm blood cardioplegia superior for myocardial protection?

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

[Anaesthesia and intensive care for cardiac surgery in France: results of the three days national survey realised in 2001 by the club of Anaesthesia, Intensive Care and Technics in Cardiac Surgery (ARTECC)]

OBJECTIVES

Ageing of the surgical population and the evolution in anaesthetic techniques have led the Club d'anesthésie-réanimation et techniques en chirurgie cardiaque (ARTECC) to conduct a survey among French cardiac surgery centers. The aim was to profile patient population undergoing cardiac surgery and perioperative techniques employed.

STUDY

National prospective study including all adult patients undergoing cardiac surgery on January 23rd, 24th and 25th, 2001. Data were collected during the first 48 postoperative hours.

MATERIAL AND METHODS

Seven referent centers drafted a record form. Sixty-one centers sent back 425 patient forms, 399 were analyzed. The following were statistically studied: type of surgery, patient characteristics, preoperative treatment, monitoring, anaesthesia, cardio-pulmonary bypass (CPB) characteristics, duration of mechanical ventilation, length of stay in intensive care unit, postoperative complications.

RESULTS

Patient mean age was 64.3 +/- 13.3 years. Patients over 80-year-old represented 2.5% of the population. Beating heart coronary aortic bypass grafts (13% surgery) and preoperative transoesophagal echography were not frequent. Propofol and sufentanil were the main anaesthetic agents used. There was a marked trend for fast-track procedures.

CONCLUSIONS

The ARTECC study pointed out some reserve in practices and that the impact of new techniques seems limited. Regular use of studies of that kind will provide an effective tool to compare national practices.

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSIONS

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