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Digoxin, hypercalcaemia, and cardiac conduction
A Vella1, T C Gerber, D L Hayes
1Department of Internal Medicine, Mayo Clinic & Foundation, Rochester, MN 55905, USA.
Insights
Hypercalcaemia can cause cardiac arrhythmias, especially when combined with digoxin. Discontinuing digoxin and correcting high calcium levels resolved a patient's symptomatic arrhythmia.
Area of Science:
- Cardiology
- Oncology
- Endocrinology
Background:
- Hypercalcaemia typically shortens the QT-interval.
- Clinically significant arrhythmias due to hypercalcaemia are rare.
- Concomitant digoxin therapy or cardiac disease can increase arrhythmia risk.
Observation:
- A patient with hypercalcaemia secondary to lung cancer developed a symptomatic arrhythmia.
- The patient was concurrently receiving digoxin therapy.
- The arrhythmia resolved upon digoxin withdrawal and correction of hypercalcaemia.
Findings:
- Hypercalcaemia, particularly with digoxin, can precipitate symptomatic arrhythmias.
- The case highlights the potentiating effect of digoxin on hypercalcaemia-induced cardiac events.
- Successful management involved addressing both hypercalcaemia and digoxin exposure.
Implications:
- Consider hypercalcaemia in unexplained bradyarrhythmias.
- Discontinue digoxin in patients with hypercalcaemia.
- Evaluate for rhythm disorders in hypercalcaemic patients undergoing treatment.
Abstract:
The cardiac effects of hypercalcaemia are usually manifest as a shortening of the QT-interval. Hypercalcaemia is infrequently associated with a clinically manifest arrhythmia. However, concomitant therapy with digoxin or underlying cardiac disease can potentiate the arrhythmogenic effects of hypercalcaemia, leading to a symptomatic rhythm disorder. We describe a symptomatic arrhythmia, which developed in a patient with hypercalcaemia secondary to squamous cell carcinoma of the bronchus. The patient was on digoxin therapy at the time. The arrhythmia did not recur after discontinuation of digoxin therapy and correction of the hypercalcaemia. Because of its effect on cardiac conduction, hypercalcaemia should be considered in the evaluation of any patient with an unexplained bradyarrhythmia. Conversely, patients with hypercalcaemia should discontinue digoxin therapy and be evaluated for the presence of rhythm disorders while receiving appropriate treatment for hypercalcaemia.