Why Does Hyperkalaemia Cause Cardiac Arrest?

Why Does Hyperkalaemia Cause Cardiac Arrest?

Inputs by Dr. Sanjeevkumar Kalkekar,
Consultant, Cardiology, at Apollo Hospitals, Navi Mumbai.

Hyperkalaemia arises when the concentration
of potassium in the bloodstream goes above a certain limit, throwing the body’s
internal pH balance out of the normal functioning. The chief causes of
Hyperkalaemia are potassium sifting out of cells into the blood circulation,
diseases of the adrenal gland, kidney dysfunction and medications.

One of the reasons why your internal pH
balance is so essential is that many of the cells depend on a negative voltage
gradient across their cell membranes to function as usual. That negative
gradient is what makes it possible for the cell to respond to the hormones and
other chemical messengers that tell it what to do. One of the ways cells
maintain that pitch, is by adjusting the amount of potassium, a positively
charged ion, inside the membrane in opposition to outside.

If the potassium levels in the bloodstream
get too high, the condition known as Hyperkalaemia, it hyperpolarizes the
membrane, which changes the amount and type of signalling that activates cell
activity. Any cells that rely on this signalling, such as the nerves, the
heart, and muscle cells, start to go out of order and may cause Cardiac Arrest.
Occasionally, when severe, it results in numbness, palpitations, muscle
weakness, or muscle pain.

Different muscles in your heart may start contracting at different times; a condition called Arrhythmia.