title: Magnesium flux during open heart surgery. The effect of St Thomas' Hospital cardioplegia solution.
abstract: The Hearse St Thomas' Hospital cardioplegia infusate is one method of preserving the myocardium in the absence of coronary perfusion, during open heart surgery. The infusate contains 16 mmol magnesium/litre and 20 mmol potassium/litre. Peri-operative plasma magnesium levels and urinary excretion of magnesium have been measured, when the infusate was returned to the circulation in 12 patients. The plasma level (+/- SEM) rose to 1.86 mmol/litre (+/- 0.1) 5 minutes after cardiopulmonary bypass commenced, was 1.57 mmol/litre (+/- 0.09) shortly before termination of cardiopulmonary bypass but was normal on the first day after surgery. Urinary excretion of magnesium was 55% of the administered quantity by Day 1 and 77% by the second day. Two patients excreted less than 40% of the administered magnesium within 24 hours probably indicating magnesium depletion. There were no adverse effects from a magnesium load of 16--32 mmol magnesium given during cardiopulmonary bypass.
mesh_terms: D000328:Adult; D006348:Cardiac Surgical Procedures; D002315:Cardiopulmonary Bypass; D006324:Heart Arrest, Induced; D006400:Hematocrit; D006801:Humans; D007263:Infusions, Parenteral; D008274:Magnesium / Q000008:administration & dosage / Q000378:metabolism*; D009206:Myocardium; D011188:Potassium / Q000008:administration & dosage; D012709:Serum Albumin / Q000378:metabolism
chemical_list: D012709:Serum Albumin; D008274:Magnesium; D011188:Potassium