|Year : 2016 | Volume
| Issue : 1 | Page : 18-22
Prevention of reperfusion tachyarrhythmia after CABG: magnesium versus lidocaine
Magdy M Atallah MD
Cardiothoracic Anesthesia Unit, Department of Anesthesia & SIC, Mansoura Faculty of Medicine, Mansoura, Egypt
|Date of Submission||10-Feb-2014|
|Date of Acceptance||07-Apr-2015|
|Date of Web Publication||17-Mar-2016|
Magdy M Atallah
Cardiothoracic Anesthesia Unit, Department of Anesthesia & SIC, Mansoura Faculty of Medicine, Mansoura
Source of Support: None, Conflict of Interest: None
Reperfusion tachyarrhythmia after aortic cross-clamp (ACC) release is one of the most commonly encountered complications after coronary artery bypass grafting (CABG) surgery, and its control may save these patients.
Materials and methods
Ninety patients who had undergone CABG surgery were enrolled in this study. Patients were assigned randomly to three groups (30 patients each). The lidocaine group (LIDO) group received lidocaine (2 mg/kg) in 100 ml isotonic saline, the magnesium group (MAGN) group received magnesium (30 mg/kg) diluted in 100 ml of an isotonic saline 0.9% solution, and the control group received 100 ml normal saline by a pump circuit 3-5 min before ACC release. Anesthetic management, weaning protocol from cardiopulmonary bypass, was standardized. All the patients were monitored after the release of ACC and electrical rhythms (including ventricular fibrillation and supraventricular tachyarrhythmia) were recorded.
Incidences of postrelease of ACC and ventricular fibrillation were lower in the lidocaine and magnesium groups compared with the control group [7 (23%), 4 (13%) vs. 11 (36%)] (P = 0.042). Also, the incidence of an atrioventricular block postrelease ACC was higher in the lidocaine group compared with the magnesium and control groups [7 (23%) vs. 2 (6%) and 3 (10%), respectively] (P = 0.039). The need for a temporary pace maker was higher in the lidocaine group compared with the magnesium and control groups [7 (23%) vs. 2 (6%) and 1 (3%), respectively] (P = 0.044). Also, the total duration of ICU stay was shorter in the magnesium group compared with the lidocaine and control groups.
The administration of lidocaine and magnesium sulfate before the release of ACC reduced the incidence of ventricular fibrillation. The administration of magnesium shortened the ICU stay in adult patients undergoing CABG surgery by cardiopulmonary bypass. However, the administration of Lidocaine was associated with more transient atrioventricular block.
Keywords: arrhythmia, coronary artery bypass grafting, lidocaine, magnesium
|How to cite this article:|
Atallah MM. Prevention of reperfusion tachyarrhythmia after CABG: magnesium versus lidocaine. Ain-Shams J Anaesthesiol 2016;9:18-22
|How to cite this URL:|
Atallah MM. Prevention of reperfusion tachyarrhythmia after CABG: magnesium versus lidocaine. Ain-Shams J Anaesthesiol [serial online] 2016 [cited 2019 Sep 18];9:18-22. Available from: http://www.asja.eg.net/text.asp?2016/9/1/18/178874
| Introduction|| |
The occurrence of reperfusion tachyarrhythmia after the release of aortic cross-clamp (ACC) following coronary artery bypass grafting (CABG) is a major complication and has been shown to be because of the release of oxygen free radicals and calcium overload. Reperfusion tachyarrhytmia has been shown to be 11-54% supraventricular and 1.8-13% ventricular  . Myocardial protection with different modalities of cardioplegia, especially cold blood, has resulted in significant improvement in the outcomes of cardiopulmonary bypass (CPB) in CABG and to maintain sinus rhythm  . Many approaches have been used to decrease such arrhythmias including DC; however, its recurrence increases oxygen demand and may lead to ventricular dilatation, injury, and difficult weaning from CPB.
Amiodarone has been proven to be superior in some studies , whereas other studies have reported its failure compared with placebo in the control of such arrhythmia  . Lidocaine has been shown to increase the threshold for ventricular fibrillation (VF) by binding to sodium channels (class Ib), decreasing the slope of phase 4 depolarization, and increasing the diastolic threshold potential  . Also, magnesium plays an important role in preserving cardiac rhythm by stabilizing membrane function  .
This study hypothesized that both lidocaine and magnesium had antiarrhythmic pharmacological properties that may play a role in the decrease or the prevention of post-CABG arrhythmia ,,,,, .
Thus, this study aimed to compare the efficacy of magnesium sulfate and lidocaine in the prevention and treatment of ventricular and supraventricular arrhythmias following CABG.
| Materials and methods|| |
Ninety patients who had undergone CABG surgery were enrolled in this study in the Cardiothoracic Unit at Mansoura University Hospital from April 2013 till October 2014. The study was approved by the Medical Ethics Committee and informed consent was obtained from every patient. Exclusion criteria included any arrhythmia other than sinus rhythm, use of drugs causing electrolyte imbalance (e.g. magnesium sulfate, diuretics), poor left ventricular function (defined as an ejection fraction of <40%), metabolic, surgical, or major organ dysfunction, and those with severe hyperkalemia at the time of ACC release. All patients were subjected to preoperative clinical, laboratory, radiological, and echocardiographic investigations. All patients continued their preoperative medications up to and including the day of surgery and received anesthetic premedication of 2 mg midazolam and 4 mg morphine intravenously half an hour preoperatively. After arrival to the operating room, routine monitoring was established with five-lead ECG, peripheral pulse oximetry, and capnogram. A left radial artery (20 G) and a right internal jugular or a subclavian central venous catheter were inserted under lidocaine (1%) anesthesia to monitor the arterial blood pressure, blood gases, blood sampling, and central venous pressure.
Anesthetic management was standardized. Anesthesia was induced with fentanyl 5-10 μg/kg and midazolam 100 μg/kg and 0.5 mg/kg atracurium to provide neuromuscular blockade to facilitate tracheal intubation to ventilate the lungs with 100% oxygen, whereas anesthesia was maintained with isoflurane 0.4-0.8% with a continuous infusion of fentanyl and midazolam, which was adjusted if clinically required.
During all procedures, heart rate, rhythm, and computerized ST segment analysis were monitored and oxygen saturation was monitored by pulse oximetry. A urinary catheter was placed to monitor urine output, and rectal and nasopharyngeal temperatures were monitored continuously. The heart was approached through a standard median sternotomy in all patients. The ascending aorta, SVC, and IVC were canulated after sufficient heparinization for CPB using a nonpulsatile pump flow rate of 2.0-2.4 l/m 2 /min. Moderate hemodilution and mild systemic hypothermia (32°C) through blanket and topical ice bags were used. After ACC insertion, the cold blood cardioplegia was delivered until asystole occurred. Myocardial cooling using packed iced saline was used. Cardioplegia was reinjected every 30 min or on the return of electrical activity of the heart. Hematocrit was maintained at 20-25% during CPB, with the addition of blood as necessary. Serial arterial blood gas analysis was carried out and activated clotting time was determined as appropriate. The mean arterial blood pressure was maintained above 50 mmHg using either intravenous nitroglycerine, epinephrine, or norepinephrine.
Patients were assigned randomly using a computer program to three groups (30 patients each): the lidocaine group (LIDO) received lidocaine hydrochloride (2 mg/kg) in 100 ml isotonic saline, the magnesium group (MAGN) received magnesium sulfate (30 mg/kg) diluted in 100 ml of an isotonic saline 0.9% solution, and the control group received 100 ml normal saline by a pump circuit 3-5 min before ACC release. Infusion was performed over less than 5 min.
All the patients were monitored after the release of ACC and any occurance of an electrical rhythm other than sinus rhythm (including VF and supraventricular tachyarrhythmia) was recorded, and if prolonged more than ten seconds VF or repeated supraventricular fibrillation was encountered, electrical defibrillation (internal biphasic DC started with 100, 100, and 200 J stepwise) with serial check to arterial blood gases and electrolytes.
Patients were weaned from CPB when rewarmed to a core temperature of at least 37°C and were hemodynamically stable. At the time of ACC release, pH of the blood, arterial O 2 and CO 2 tensions, hemoglobin, hematocrit and serum potassium, Na, Ca, and Mg were recorded. The patients' demographic data including ECG, ejection fraction, and numbers of grafts were also obtained. After completion of the surgical procedure, adequate rewarming was achieved, followed by careful standard weaning. After removal of the aortic cannula, intravenous protamine was administered slowly at a dose of 3 mg/kg to reverse heparinization and ACT to be near basal value (80-120 seconds).
All surgeons, anesthetic care givers, and perfusionists were blinded to the study.
Statistical analyses were carried out using the SPSS software (version 17.0; SPSS Inc., Chicago, Illinois, USA). χ2 -Test was used to compare the rate of the occurrence of VF. Analysis of variance was used to compare K+, pH, hematocrit, cross-clamping time (min), VF, and supraventricular tachycardia. For significance of P values, a post-hoc test was carried out using the Tukey t-test. Data are represented as mean ± SD and n (%).
The number of patients was chosen on the basis of occurrence of arrhythmia of ~30-50% following the release of cross-clamp in most studies. χ2 -Test with 80% power and an a error of 0.0167 showed that 28 patients were required in each group to adjust comparison in three groups. A P value of less than 0.05 was considered significant.
| Results|| |
Preoperative data of age, sex, BSA, history of hypertension, diabetes, COPD, myocardial infarction, creatinine level (mg/dl), and left ventricular ejection fraction showed no significant differences between the groups studied [Table 1].
Intraoperative data of anesthesia time, ACC time, perfusion time, and number of grafts used were statistically nonsignificant among the groups studied. Blood pH values and electrolytes preinfusion showed a nonsignificant difference among the groups studied [Table 2]. Magnesium level on arrival to ICU was significantly higher in the magnesium group compared with the Lidocaine and control groups (3.1 ± 0.06, 1.9 ± 0.5, 1.7 ± 0.2, respectively). Also, total hospital stay showed a nonsignificant difference among the groups studied [Table 2]. However, total ICU stay (h) was significantly shorter in the magnesium group compared with the lidocaine and control groups (22.4 ± 4.3, 28.1 ± 4.6, and 34 ± 5.9, respectively) [Table 2].
|Table 2 Intraoperative data before aortic cross-clamp release, ICU stay (h), and length of hospital stay (days) of the groups studied|
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Supraventricular tachyarrhythmia and need for DC shock showed no significant differences among the groups studied intraoperatively and postoperatively [Table 3]. However, incidence of postrelease of ACC and VF was lower in the lidocaine and magnesium groups compared with the control group [7 (23%), 4 (13%) vs. 11 (36%)]. Also, the incidence of atrioventricular (AV) block postrelease ACC was higher in the lidocaine group compared with the magnesium and control groups [7 (23%) vs. 2 (6%) and 3 (10%), respectively] [Table 3]. The need for a temporary pace maker was higher in the lidocaine group compared with the magnesium and control groups [7 (23%) vs. 2 (6%) and 1 (3%), respectively]. There were no significant differences in these variables in the ICU among the groups studied [Table 3].
|Table 3 Incidence of arrhythmia, need for DC shock, or intraaortic balloon|
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| Discussion|| |
This study showed that prophylactic treatment with magnesium sulfate or lidocaine before ACC release was associated with a lower incidence of VF and shorter ICU stay in comparison with treatment with placebo.
Also, the incidence of transient AV block was higher in the Lidocaine group compared with the other groups.
The results of this study were in agreement with those of others as one study reported a decrease in the incidence of ventricular arrhythmias of up to 50% when 2 g of prophylactic magnesium was administered intraoperatively, with no effect on supraventricular arrhythmias , . Also, Ayoub et al.  reported on prophylactic treatment with magnesium after supraventricular and ventricular arrhythmias. Most of the studies agreed on the principal mode of action of magnesium as a plasma membrane-stabilizing agent of the myocardium and in maintaining the intracellular to extracellular K + ratio.
However, Shiga et al.  , in a meta-analysis, reported on one study that proved that magnesium at a dose greater than 4 g, which was higher than the dose used in this study, was associated with bradycardia requiring pacing for 24 h and mild hypotension, which is responsible for fluid administration .
In terms of the use of lidocaine, the results of Baraka et al.  were in agreement with ours for its protective effect on the incidence of VF following ACC release, and attributed these results to the mode of action of lidocaine as a sodium channels blocker and attenuating phase 4 depolarization. They also added that lidocaine increased cardiac output following weaning after bypass  . The same study did not report incidences of AV block as in our study, which may be related to the use of 100 mg lidocaine in their study, which is a lower dose than that used in this study. However, incidences of AV block were reported in another study using a high dose of lidocaine in cardioplegia 500 mg/l, with a significant decrease in VF compared with the control group (96 vs. 4%). This may be attributed to an increase in the diastolic electric current threshold in Purkinje fibers  .
In a similar study during CABG surgery, using the same dose of magnesium and a lower dose of lidocaine of 1.5 mg/kg, it was found that they both decreased VF. They reported no AV block in contrast to this study, which may be attributed to the higher dose of lidocaine used in this study  .
The total duration of ICU stay (h) was shorter in the magnesium group (22.4 ± 4.3) compared with the lidocaine group (28.1 ± 4.6) because of the lower need for pacing and fewer incidences of AV block and VF compared with the control group (34 ± 5.9).
| Conclusion|| |
The administration of lidocaine and magnesium sulfate before the release of ACC reduced the incidence of the administration of magnesium shortened the ICU stay in adult patients undergoing CABG surgery by CPB. However, administration of lidocaine was associated with more transient AV block and the need for temporary pacing.
| Acknowledgements|| |
Conflicts of interest
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[Table 1], [Table 2], [Table 3]