UMEM Educational Pearls

Title: Calcium for Hyperkalemia: Does it Really Stabilize the Cardiac Membrane?

Category: Pharmacology & Therapeutics

Keywords: hyperkalemia, calcium, cardiac conduction, resting membrane potential (PubMed Search)

Posted: 9/11/2024 by Alicia Pycraft (Updated: 9/12/2024)
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The benefits of calcium treatment for hyperkalemia have historically been attributed to “membrane stabilization,” as it has been hypothesized to restore cardiac resting membrane potential. However, the true mechanism by which calcium improves cardiac function in this setting remains unclear. This has led to inconsistencies in the clinical threshold for treating hyperkalemia with calcium.

Piktel et al. recently conducted an experimental study investigating the adverse electrophysiologic effects of hyperkalemia and therapeutic effects of calcium treatment in isolated canine myocytes using ex vivo tissue and in vivo cellular techniques.

Key study findings:

Effects of hyperkalemia:

Slowed cardiac conduction velocity by 67% ± 7% (p<0.001)
Shortened cardiac action potential duration by 20% ± 10% (p<0.002)
Elevated cardiac resting membrane potential
Caused QRS widening in all preparations, with appearance of the “sine wave” pattern in severe hyperkalemia

Effects of calcium treatment in the setting of hyperkalemia:

Increased cardiac conduction velocity by 44% ± 18% (p<0.002)
Caused narrowing of the QRS complex and normalization of ECG
NO effect on action potential or resting membrane potential
Effects were reversed with the addition of L-type calcium channel blockade with verapamil

Limitation:

Does not account for concomitant acidosis, bradycardia, or arrhythmias which may be present in patients with hyperkalemia

Bottom line: Findings of this study suggest that calcium's beneficial effects in hyperkalemia are not attributed to “membrane stabilization,” but rather to restoration of conduction velocity through L-type calcium channels and subsequent narrowing of the QRS complex. This supports calcium treatment in hyperkalemia when the ECG shows conduction slowing and QRS widening.

References

Piktel JS, Wan X, Kouk S, Laurita KR, wilson LD. Beneficial effect of calcium treatment for hyperkalemia is not due to “membrane stabilization” Crit Care Med. 2024; 52(00): 1-10.