Digoxin Toxicity

Digoxin toxicity is a clinical syndrome, not a laboratory diagnosis. Excessive cardiac glycoside effect can increase abnormal impulse generation while impairing impulse conduction. A patient may therefore have ventricular ectopy, bradycardia, atrial tachycardia with block, or several rhythm disturbances during the same episode. The serum concentration supports the assessment but does not define toxicity. Renal impairment, hypokalemia, hypomagnesemia, hypercalcemia, advanced age and interacting medicines can increase risk or myocardial sensitivity. A concentration drawn during distribution can also mislead. Look first for a change from baseline: new anorexia, nausea or vomiting; confusion or delirium; blurred or yellow vision; a slow or irregular pulse; or a new ECG abnormality. Establish whether exposure is acute, acute-on-chronic or chronic, then assess renal function, electrolytes, rhythm and perfusion.