Minimally-Diluted Blood Cardioplegia Supplemented With Potassium and Magnesium for Combination of 'Initial, Continuous and Intermittent Bolus' Administration

Role of Prophylactic Magnesium Supplementation in Prevention of Postoperative Atrial Fibrillation in Patients Undergoing Coronary Artery Bypass Grafting: a Systematic Review and Meta-Analysis of 20 Randomized Controlled Trials

Background

Several randomized trials have evaluated the efficacy of prophylactic magnesium (Mg) supplementation in prevention of post-operative atrial fibrillation (POAF) in patients undergoing cardiac artery bypass grafting (CABG). We aimed to determine the role of prophylactic Mg in 3 different settings (intraoperative, postoperative, intraoperative plus postoperative) in prevention of POAF.

Methods

A systemic literature search was performed (until January 19, 2019) using PubMed, EMBASE, Web of Science, and Cochrane Central Register of Controlled Trials to identify trials evaluating Mg supplementation post CABG. Primary outcome of our study was reduction in POAF post CABG.

Results

We included a total of 2,430 participants (1,196 in the Mg group and 1,234 in the placebo group) enrolled in 20 randomized controlled trials. Pooled analysis demonstrated no reduction in POAF between the two groups (RR 0.90; 95% CI, 0.79-1.03; p=0.13; I2=42.9%). In subgroup analysis, significant reduction in POAF was observed with postoperative Mg supplementation (RR 0.76; 95% CI, 0.58-0.99; p=0.04; I2=17.6%) but not with intraoperative or intraoperative plus postoperative Mg supplementation (RR 0.77; 95% CI, 0.49-1.22; p = 0.27; I2=49% and RR 0.92; 95% CI, 0.68-1.24; p = 0.58; I2=51.8%, respectively).

Conclusions

Magnesium supplementation, especially in the postoperative period, is an effective strategy in reducing POAF following CABG.

A double-blind randomized clinical trial comparing different doses of magnesium in cardioplegic solution for prevention of atrial fibrillation after coronary artery bypass graft surgery

AIMS

This study aims to compare different doses of magnesium administered via cardioplegic solutions to prevent atrial fibrillation (AF) after coronary artery bypass graft (CABG) surgery.

METHODS

A total of 120 patients who were scheduled for elective CABG surgery using cardiopulmonary bypass were enrolled in this double-blind, randomized clinical trial. After fulfilling the inclusion criteria, they were randomly allocated into three groups (A, B, and C). Patients in groups A, B, and C received 60, 80, and 100 mg/kg of magnesium sulfate via cardioplegic solutions during aortic cross-clamp, respectively. Postoperative AF was assessed by continuous ECG monitoring during 3 days after surgery. Also serum magnesium, potassium, and calcium levels were assessed during the study period.

RESULTS

The findings revealed significant differences in four point measurements of serum magnesium level after surgery (P<.001). In particular, it was observed that 10 (26.3%) patients in group A, 4 (10%) patients in group B, and 2 (5.4%) patients in group C had AF after surgery. This indicates patients receiving magnesium at doses of 80 and 100 mg/kg had lower rates of AF occurrence than those receiving 60 mg/kg dose of magnesium (P=.02). Additionally, no significant difference was found in serum calcium and potassium concentration between the three groups throughout the study period.

CONCLUSION

Magnesium administration via the cardioplegic solution during aortic cross-clamping at doses of 80 and 100 mg/kg can reduce the risk of AF occurrence after CABG compared to the dose of 60 mg/kg. Considering the lower rate of AF incidence and shorter length of ICU stay in patients receiving 100 mg/kg of magnesium, it seems reasonable to administer 100 mg/kg magnesium during aortic cross-clamp to prevent postoperative AF.

Does magnesium-supplemented cardioplegia reduce cardiac injury? A meta-analysis of randomized controlled trials

BACKGROUND

Magnesium is often used to supplement cardioplegic solutions during cardiopulmonary bypass due to its cardioprotective effect during ischemia and reperfusion. The aim of this meta-analysis was to evaluate the effects of magnesium-supplemented cardioplegia versus an inactive (placebo) control cardioplegia on reducing cardiac injury after cardiac arrest surgery, as found by randomized, controlled trials.

METHODS

The Medline, Cochrane Library, and Chinese literature databases (CJFD, CBM, CSJD, Wanfang) were comprehensively searched for reports of randomized, controlled trials (RCTs) evaluating magnesium-supplemented cardioplegic solutions. The clinical parameters and outcomes of interest were the incidence of postoperative low cardiac output, auto-rebeating rate, ICU stay length, new onset postoperative atrial fibrillation, peak value of CK-MB (and/or cTnI), incidence of myocardial infarction, and in-hospital mortality.

RESULTS

Ten trials, with a total of 1214 patients, were included. The frequency of low cardiac output, inotropic utilization, and myocardial infarction, as well as auto-rebeating rate, length of ICU stay and in-hospital mortality, were similar between the two groups. There was a marginal reduction in the incidence of new-onset postoperative atrial fibrillation in the magnesium-supplemented cardioplegia group.

CONCLUSIONS

The advantage of magnesium-supplemented cardioplegia, compared with cardioplegia without magnesium, remains unconvincing based on the current evidence. The decision to add magnesium to the cardioplegic solution to a patient undergoing cardiac arrest surgery should be carefully considered.

"Initial, continuous and intermittent bolus" administration of minimally-diluted blood cardioplegia supplemented with potassium and magnesium for hypertrophied hearts

BACKGROUND

Hypertrophied hearts are subject to the deleterious effects of intraoperative ischemia-reperfusion, and stable maintenance of myocardial cardioplegic arrest is essential. Continuous cardioplegia infusion appears an ideal modification to overcome this issue, except for a large amount of crystalloid solution infused into the myocardium. We previously introduced "initial, continuous and intermittent bolus" administration of minimally-diluted blood cardioplegia (mini-BCP) supplemented with potassium and magnesium, and this study was designed to elucidate its efficacy in patients with hypertrophied hearts.

METHODS

Thirty patients (M:F=17:13, 69.2+/-7.8 years) with left ventricular mass index greater than 150 g/m(2) who underwent aortic valve replacement between 1996 and 2002 were enrolled, and were allocated to one of the two groups. The same infusion protocol was used for both groups as follows: initial and intermittent (every 20 min) BCP was antegradely infused for 2 min at the rate of 200 mL/min, and continuous retrograde BCP flow rate was set at 60-100mL/min. Group C (n=15) received 4:1-diluted BCP modified with Buckberg solution, and Group M (n=15) were given mini-BCP supplemented with potassium (initial/others: 15.4/9.8 mEq/L) and magnesium (initial/others: 6.5/4.0 mEq/L).

RESULTS

Stable cardioplegic arrest was maintained in all study patients, and total amount of crystalloid solution as cardioplegia was lesser in Group M (79.4+/-27.5 mL) than in Group C (937.3+/-372. 1mL, p<0.01). Group M showed a higher incidence of spontaneous heartbeat recovery after aortic unclamping (13 versus 6, p<0.05) and a lower incidence of postoperative atrial fibrillation (0 versus 5, p<0.05). Postoperatively, maximum dopamine dose (3.35+/-2.27 microg/kg/min versus 5.49+/-2.30 microg/kg/min, p<0.05) and peak plasma creatine kinase-myocardial band (CK-MB) (21.7+/-7.2 IU/L versus 28.8+/-8.4 IU/L, p<0.05) were lower in Group M. Early postoperative echocardiography revealed a lower incidence of paradoxical ventricular septal motion (M versus C; 3 versus 10, p<0.05) and greater left ventricular ejection fraction (M versus C; 70.7+/-4.0% versus 67.0+/-5.3%, p<0.05) in Group M.

CONCLUSIONS

These results suggest that "initial, continuous and intermittent bolus" administration of mini-BCP, supplemented with potassium and magnesium, is a novel modification for patients with hypertrophied hearts in terms of simplifying the maintenance of cardioplegic arrest with beneficial myocardial protective effects.

Left atrial diameter is a simple indicator of a deficiency in atrial natriuretic peptide secretion in patients with mitral stenosis: efficacy of postoperative supplementation with synthetic human alpha-atrial natriuretic peptide

OBJECTIVE

With regard to a deficiency in atrial natriuretic peptide (ANP) secretion, the relationship between plasma ANP and left atrial diameter measured by echocardiography was examined and the efficacy of postoperative supplementation was evaluated.

METHODS

(1) Ninety-six patients with mitral valve disease from 1997 to 2002 (M:F = 65:31, mean-age 65.3 +/- 8.9 years) were studied for relationship analyses. (2) Twenty-six patients with mitral stenosis and left atrial diameter > or = 60 mm undergoing mitral valve replacement (M:F = 17:9, mean-age 67.4 +/- 7.5 years) were randomly allocated to one of two groups; ANP-treated group (n = 13, 0.05 microg/kg/min of synthetic human alpha-ANP was postoperatively administered) and Control group (n = 13).

RESULTS

(1) There were significant positive correlations between left atrial diameter and plasma renin-activity (r = 0.690, P < 0.01) and between left atrial diameter and plasma aldosterone (r = 0.757, P < 0.01). The maximum value of plasma ANP was 249.5 pg/mL accompanied with 56.2 mm of left atrial diameter in 29 patients suffering from mitral stenosis. There was a significant negative correlation between left atrial diameter and ANP in patients with left atrial diameter > 56.2 mm (r = - 0.725, P < 0.0001), whereas there was a significant positive correlation in patients with left atrial diameter < or = 56.2 mm (r = 0.529, P = 0.0066). (2) At 24 hours after operation, the ANP-treated group showed significantly lower plasma renin-activity (9.2 +/- 3.3 versus 36.2 +/- 7.4 ng/mL/h) and aldosterone (113.6 +/- 36.9 versus 473.8 +/- 95.8 pg/mL) than the Control group.

CONCLUSIONS

Left atrial diameter can be a simple and useful indicator of a deficiency in endogenous ANP secretion in patients with mitral stenosis, and postoperative ANP supplementation contributes to suppressing further activation of renin-angiotensin system during the immediate postoperative period.