Menu

Calcium and Arrhythmias

by | 4 May, 2020

Login to enrol on courses and monitor progress

Hypercalcaemia

Definition

Hypercalcaemia is defined as a serum calcium concentration higher than 2.6 mM.

ECG changes

Shortening of the QT interval is the most common ECG change in hypercalcaemia. Severe hypercalcaemia can lead to atrioventricular block, complete heart block and cardiac arrest.

Short QT

Short QT interval in hypercalcaemia

Pathophysiology

The mechanisms are not completely understood. Current theories suggest that the L-type calcium channel, which is responsible for the plateau phase, employs a calcium-dependent inactivation mechanism. Other theories include a reduction in the activity of the inward Na+-Ca2+-exchanger.

Hypercalcaemia allows calcium to enter cells quicker than normal for a given channel opening. Consequently, they can act on and inactivate the L-type calcium channel more rapidly. This leads to shortening of the plateau phase, which is reflected in the ST and QT intervals.

Management

Acutely, administer IV fluids to reduce serum calcium concentration and offer bisphosphonates. Any underlying causes of hypercalcaemia should be treated.

Hypocalcaemia

Definition

Hypocalcaemia is defined as a serum calcium concentration lower than 2.1 mM.

ECG changes

Prolongation of ST and QT intervals. Severe hypocalcaemia can lead to ventricular tachycardia, including torsades de pointes.

LQT

Long QT interval in hypocalcaemia

LQT

Pathophysiology

The mechanisms are not completely understood. Current theories suggest that the L-type calcium channel, which is responsible for the plateau phase, employs a calcium-dependent inactivation mechanism.

Hypocalcaemia produces a slower calcium entry into cells during the plateau phase of the action potential. Consequently, the inactivation of L-type calcium channels requires a longer length of time. This leads to a prolongation of the plateau phase, which is reflected in the ST and QT intervals.

Management

Acutely, calcium levels should be replaced, which can be achieved with orally or intravenously. Any underlying causes of hypocalcaemia should be treated.

0 Comments

Submit a Comment



Your email address will not be published. Required fields are marked *

Let's Learn Together!

All our lessons and courses are free to access and use for everybody.

Join Clinician Revision to get personalised help and see your progress.

Want to contribute to a topic, lesson or quiz?