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Magnesium administration and arrhythmias after cardiac surgery. A placebo-controlled, double-blind, randomized trial
LITERATURE REVIEW Frederick W. Campbell, MD, Editor
SCIENTIFIC ARTICLES
Leung JM, Hollenberg M, O’Kelly BF, et al: Effects of steal-prone anatomy on intraoperative myocardial ischemia. J Am Co11 Cardiol20:1205-1212,1992 The incidence of intraoperative myocardial ischemia determined by continuous intraoperative electrocardiography and transesophageal echocardiography was evaluated in 168 patients with steal-prone coronary anatomy during coronary artery surgery. Patients were randomized to receive isoflurane or sufentanil anesthesia, and hemodynamics were strictly controlled. Thirtythree percent of the 168 patients had steal-prone coronary anatomy. The incidence of ischemia was similar in patients with and without steal-prone anatomy (29% v 31%) and in patients receiving isoflurane or sufentanil anesthesia (32% v 30%). The frequency of adverse cardiac outcome was similar in patients with and without preoperative steal-prone anatomy (7% v 11%).
Jett GK, Guyton RA, Hatcher CR Jr, Abel PW: Inhibition of human internal mammary artery contractions. An in vitro study of vasodilators. J Thorac Cardiovasc Surg 104:977-982,1992 Vasodilator-induced inhibition of potassium and norepinephrinestimulated constriction of discarded human internal mammary artery ring segments was measured. The order of vasodilator potency was related to the vasoconstrictor stimulus. Nifedipine was the most potent vasodilator, whereas papaverine produced the greatest maximal inhibition of both potassium and norepinephrineinduced contraction. Nitroprusside and verapamil also inhibited contraction. Nitroglycerin, isoproterenol, and adenosine produced little or no inhibition.
England MR, Gordon G, Salem M, Chernow B: Magnesium administration and arrhythmias after cardiac surgery. A placebo-controlled, double-blind, randomized trial. JAMA 268~23952402,1992 One hundred patients undergoing elective cardiac surgery were randomized to receive 2 g of intravenous magnesium chloride or placebo intraoperatively after separation from cardiopulmonary bypass. Compared with controls, magnesium-treated patients had a significantly decreased frequency of postoperative ventricular arrhythmias (16% v 34%). Normomagnesemia postoperatively was associated with a reduced frequency of superventricular arrhythmia (17% v 37%) and higher cardiac index (2.8 v 2.5 L/min/mm) than was hypomagnesemia. Prevalence and causes of hypomagnesemia and anti-ischemic and pharmacologic properties of this ion are reviewed.
366
Downing SW, Savage EB, Streicher JS, et al: The stretched ventricle. Myocardial creep and contractile dysfunction after acute nonischemic ventricular distention. J Thorac Cardiovasc Surg 104:996-1005, 1992 Changes in left ventricular volume-pressure relationship before and after nonischemic distention were measured in continuously perfused. nonbeating ovine left ventricles arrested with oxygenated, normothermic blood-potassium perfusate. After distention 01 an intraventricular balloon to a peak pressure of 40 mmHg. static left ventricular volumes at identical pressures were significantly greater in experimental animals than in nondistended controls. The slope of the end-systolic pressure-volume relationship, a measure of contractility. decreased significantly in the distended animals.
Shanwell L, Wikman A, Ringden 0: Pretransfusion incubation of apheresis platelets at 37°C improves posttransfusion recovery. Transfusion 32:715-718, 1992 The effect of 37°C pretransfusion incubation for 1 hour 01 apheresis platelets on posttransfusion platelet count increment wa\ studied in 14 patients. Incubated or nonincubated platelets were transfused in random sequence on successive days. Blood count increment 1 hour after transfusion was 63% greater with incubated platelets than in paired controls. The effect of pretransfusion incubation of conventional pooled random-donor platelets has been inconsistent.
Murphy PJ, Connery C, Hicks GL Jr, Blumberg N: Homologous blood transfusion as a risk factor for postoperative infection after coronary artery bypass graft operations. J Thorac Cardiovasc Surg 104:10921099,1992 Culture-proved postoperative infections occurred in 6.7%’ of 238 consecutive patients undergoing first-time coronary surgery hy a single surgeon. Forty-four percent of the infections occurred away from wound sites, suggesting nonsurgical variables contributed to some infections. Factors significantly associated with an increased risk of postoperative infection by univariate analysis in this retrospective study included female sex. diabetes mellitus. and transfusion dose. Multiple linear and logistic regression analyses showed that transfusion dose was the most significant predictor of infection. Transfusion-related immunosuppression may explain the dose-dependent three- to eight-fold increased risk of postoperative infection in transfused patients.
Journalof Cardiothoraoc and Vascular Anesthesia, Vol 7, No 3 (June), 1993: pp 366-367
SCIENTIFIC ARTICLES
Leung JM, Hollenberg M, O’Kelly BF, et al: Effects of steal-prone anatomy on intraoperative myocardial ischemia. J Am Co11 Cardiol20:1205-1212,1992 The incidence of intraoperative myocardial ischemia determined by continuous intraoperative electrocardiography and transesophageal echocardiography was evaluated in 168 patients with steal-prone coronary anatomy during coronary artery surgery. Patients were randomized to receive isoflurane or sufentanil anesthesia, and hemodynamics were strictly controlled. Thirtythree percent of the 168 patients had steal-prone coronary anatomy. The incidence of ischemia was similar in patients with and without steal-prone anatomy (29% v 31%) and in patients receiving isoflurane or sufentanil anesthesia (32% v 30%). The frequency of adverse cardiac outcome was similar in patients with and without preoperative steal-prone anatomy (7% v 11%).
Jett GK, Guyton RA, Hatcher CR Jr, Abel PW: Inhibition of human internal mammary artery contractions. An in vitro study of vasodilators. J Thorac Cardiovasc Surg 104:977-982,1992 Vasodilator-induced inhibition of potassium and norepinephrinestimulated constriction of discarded human internal mammary artery ring segments was measured. The order of vasodilator potency was related to the vasoconstrictor stimulus. Nifedipine was the most potent vasodilator, whereas papaverine produced the greatest maximal inhibition of both potassium and norepinephrineinduced contraction. Nitroprusside and verapamil also inhibited contraction. Nitroglycerin, isoproterenol, and adenosine produced little or no inhibition.
England MR, Gordon G, Salem M, Chernow B: Magnesium administration and arrhythmias after cardiac surgery. A placebo-controlled, double-blind, randomized trial. JAMA 268~23952402,1992 One hundred patients undergoing elective cardiac surgery were randomized to receive 2 g of intravenous magnesium chloride or placebo intraoperatively after separation from cardiopulmonary bypass. Compared with controls, magnesium-treated patients had a significantly decreased frequency of postoperative ventricular arrhythmias (16% v 34%). Normomagnesemia postoperatively was associated with a reduced frequency of superventricular arrhythmia (17% v 37%) and higher cardiac index (2.8 v 2.5 L/min/mm) than was hypomagnesemia. Prevalence and causes of hypomagnesemia and anti-ischemic and pharmacologic properties of this ion are reviewed.
366
Downing SW, Savage EB, Streicher JS, et al: The stretched ventricle. Myocardial creep and contractile dysfunction after acute nonischemic ventricular distention. J Thorac Cardiovasc Surg 104:996-1005, 1992 Changes in left ventricular volume-pressure relationship before and after nonischemic distention were measured in continuously perfused. nonbeating ovine left ventricles arrested with oxygenated, normothermic blood-potassium perfusate. After distention 01 an intraventricular balloon to a peak pressure of 40 mmHg. static left ventricular volumes at identical pressures were significantly greater in experimental animals than in nondistended controls. The slope of the end-systolic pressure-volume relationship, a measure of contractility. decreased significantly in the distended animals.
Shanwell L, Wikman A, Ringden 0: Pretransfusion incubation of apheresis platelets at 37°C improves posttransfusion recovery. Transfusion 32:715-718, 1992 The effect of 37°C pretransfusion incubation for 1 hour 01 apheresis platelets on posttransfusion platelet count increment wa\ studied in 14 patients. Incubated or nonincubated platelets were transfused in random sequence on successive days. Blood count increment 1 hour after transfusion was 63% greater with incubated platelets than in paired controls. The effect of pretransfusion incubation of conventional pooled random-donor platelets has been inconsistent.
Murphy PJ, Connery C, Hicks GL Jr, Blumberg N: Homologous blood transfusion as a risk factor for postoperative infection after coronary artery bypass graft operations. J Thorac Cardiovasc Surg 104:10921099,1992 Culture-proved postoperative infections occurred in 6.7%’ of 238 consecutive patients undergoing first-time coronary surgery hy a single surgeon. Forty-four percent of the infections occurred away from wound sites, suggesting nonsurgical variables contributed to some infections. Factors significantly associated with an increased risk of postoperative infection by univariate analysis in this retrospective study included female sex. diabetes mellitus. and transfusion dose. Multiple linear and logistic regression analyses showed that transfusion dose was the most significant predictor of infection. Transfusion-related immunosuppression may explain the dose-dependent three- to eight-fold increased risk of postoperative infection in transfused patients.
Journalof Cardiothoraoc and Vascular Anesthesia, Vol 7, No 3 (June), 1993: pp 366-367