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Plasma and tissue digoxin concentrations in patients undergoing cardiopulmonary bypass
Insights
Digoxin levels in plasma and heart muscle varied significantly in patients undergoing cardiopulmonary bypass. Stopping digoxin 48 hours prior to surgery generally ensured safe plasma concentrations, preventing postoperative complications.
Area of Science:
- Cardiology
- Pharmacology
- Cardiovascular Surgery
Background:
- Digoxin is a cardiac glycoside used for heart failure and arrhythmias.
- Long-term digoxin treatment requires careful management, especially in patients undergoing surgery.
- Understanding digoxin distribution in myocardial and skeletal tissues is crucial for perioperative care.
Purpose of the Study:
- To measure digoxin concentrations in plasma, atrial, papillary, and skeletal muscle in patients on long-term digoxin therapy undergoing cardiopulmonary bypass.
- To investigate the relationship between digoxin dosage, discontinuation time, and tissue concentrations.
- To assess the impact of cardiopulmonary bypass on digoxin levels and correlate them with postoperative cardiotoxicity.
Main Methods:
- 32 patients on long-term digoxin therapy undergoing cardiopulmonary bypass were studied.
- Patients were grouped based on daily digoxin dose and pre-operative discontinuation interval.
- Digoxin concentrations were measured in plasma, atrial, papillary, and skeletal muscle before and after bypass.
Main Results:
- Pre-bypass mean digoxin concentrations varied across tissues: plasma (1.58 nmol/l), atria (65.2 nmol/kg), papillary muscle (121.4 nmol/kg), and skeletal muscle (16.6 nmol/kg).
- Higher digoxin doses and shorter discontinuation times correlated with higher plasma concentrations.
- No significant changes in digoxin concentrations were observed during cardiopulmonary bypass, and no clear link to postoperative cardiotoxicity was found.
Conclusions:
- Digoxin tissue concentrations are highly variable and influenced by dosage and timing of discontinuation.
- Stopping digoxin 48 hours before surgery generally achieves safe plasma levels.
- Early administration (24 hours) of higher digoxin doses (0.5 mg) was associated with postoperative complications like pulsus bigeminus.
Abstract:
Plasma myocardial, and skeletal muscle digoxin concentrations were measured in 32 patients undergoing cardiopulmonary bypass who were on long-term treatment with digoxin. The patients were divided into 4 groups according to the daily digoxin dose and the interval between discontinuation of the drug and operation. Before bypass, the mean digoxin concentrations were 1.58 nmol/l (1.24 ng/ml) in plasma 65.2 nmol/kg (50.9 ng/g) in the atria, 121.4 nmol/kg (94.98 ng/g) in 11 papillary muscles, and 16.6 nmol/kg (13.0 ng/g) in skeletal muscle. Mean atrial digoxin concentrations were significantly lower tham mean papillary muscle concentrations in 11 patients. Ratios of plasma of myocardial or skeletal muscle digoxin concentrations were very variable. Generally digoxin concentrations were higher in patients on the larger digoxin dose and with the shorter discontinuation time before surgery. These differences attained significance only with plasma digoxin concentrations. There was a slight fall in plasma digoxin concentration during cardiopulmonary bypass but no significant differences were observed between plasma, atrial, or skeletal muscle digoxin concentrations before and at the end of bypass. No clear relation was seen between plasma or atrial digoxin concentrations and postoperative cardiotoxicity. Stopping digoxin 48 hours before operation appeared to account for pre- or post-bypass plasma digoxin concentrations of less than 1.0 nmol/l (0.8 ng/ml) in most of the instances encountered, whereas the 3 patients who developed pulsus bigeminus postoperatively had received 0.5 mg digoxin only 24 hours before operation.