The impact of hyperkalemia on the heart

Written by Wei Shi Liang

Intensive Care Unit

Updated on December 15, 2024

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The effects of hyperkalemia on the heart mainly manifest in the following ways: First, it affects the excitability of the myocardium, as hyperkalemia can cause reduced or even absent myocardial excitability; second, it impacts myocardial conductivity. In hyperkalemia, due to the reduced resting potential, the amplitude and speed of the action potential's phase zero decrease, leading to slowed excitability spread and reduced conductivity; third, it influences the automaticity of the myocardium. In hyperkalemia, due to slowed automatic depolarization, the automaticity is reduced. Additionally, hyperkalemia produces characteristic changes in the electrocardiogram, such as depression or disappearance of the P wave, prolongation of the PR interval, widening of the S wave, and narrowing and peaking of the T wave, which are the main changes in the electrocardiogram due to hyperkalemia.

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Written by Wei Shi Liang

Intensive Care Unit

34sec

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Does hyperkalemia cause a fast or slow heart rate?

Hyperkalemia often causes a slowed heart rate and is associated with various arrhythmias. When serum potassium is between 6.6 to 8.0 mmol/L, tented T-waves may be observed. When serum potassium levels rise rapidly, it can lead to ventricular tachycardia or even ventricular fibrillation. On the other hand, a slow increase in serum potassium can cause conduction blocks, and in severe cases, may lead to cardiac arrest. These are the heart rate changes caused by hyperkalemia, which typically result in a slower heart rate.

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Written by Zhao Xin Lan

Endocrinology

1min 27sec

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Principles of treatment for hyperkalemia

First, to counteract the cardiac inhibitory effects of potassium, calcium salts can be injected, and sodium bicarbonate can be used to alkalinize the blood. Then, an infusion of hypertonic glucose and insulin can be administered to promote the internal movement of potassium ions. Secondly, to promote the excretion of potassium, diuretics can be used. The second method involves the use of cation exchange resins and sorbitol. The third method employs dialysis therapy, which can include both hemodialysis and peritoneal dialysis. The fourth method is to reduce the sources of potassium, stop a high potassium diet or the use of potassium-containing drugs. In cases of severe hyperkalemia, where there is a life-threatening emergency, urgent measures should be taken, primarily the intravenous administration of calcium ion antagonists to counteract the cardiac toxicity of potassium. In cases of severe arrhythmias or even cardiac arrest, emergency installation of a pacemaker or defibrillation can be carried out, and respiratory muscle paralysis may require ventilatory support. (Medication use should be under the guidance of a doctor)

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Written by Chen Li Ping

Endocrinology

1min 52sec

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What are the causes of hyperkalemia?

The first reason is the excessive intake or administration of potassium, which can lead to hyperkalemia. For example, consuming foods that are very rich in potassium, or intravenously infusing solutions containing potassium. Additionally, the use of potassium salts of penicillin can also cause hyperkalemia, as well as the transfusion of stored blood, which can easily lead to hyperkalemia. Besides excessive intake and administration of potassium, diseases related to reduced excretion can also cause hyperkalemia, such as the most common instances during acute or chronic renal failure, where patients are prone to hyperkalemia. Furthermore, patients with reduced adrenal cortex function, such as aldosterone deficiency or Addison's disease, are also prone to hyperkalemia. Additionally, the use of diuretics that inhibit potassium excretion, notably spironolactone—a potassium-sparing diuretic—can also cause an increase in blood potassium levels. Another reason is a change in potassium distribution, such as when potassium moves from inside the cells to the outside, which can easily lead to hyperkalemia. This is common in cases of tissue damage, such as muscle contusion, or electrical burns, and tissue hypoxia, which also can easily lead to a change in potassium distribution, causing an increase in extracellular potassium. If hemolysis occurs in a test tube, such as if the venipuncture takes too long, or in conditions like leukocytosis or severe shaking of the blood sample, these might also lead to hyperkalemia. (The use of medications should be under the guidance of a doctor.)

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Written by Wei Shi Liang

Intensive Care Unit

42sec

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The effects of hyperkalemia on the body

Hyperkalemia affects the body mainly in three aspects. Firstly, hyperkalemia impacts muscle tissues, clinically manifesting as symptoms such as muscle tremors. Secondly, the effect of hyperkalemia on the heart primarily manifests as decreased excitability, conductivity, and automaticity of the myocardium. It affects electrocardiograms, characterized by a depressed P wave, widened QS wave, reduced R wave, and elevated T wave. Thirdly, hyperkalemia affects acid-base balance; during hyperkalemia, potassium efflux from cells can lead to metabolic acidosis, resulting in alkaline urine.

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Written by Zhao Xin Lan

Endocrinology

56sec

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How should hyperkalemia be managed?

First, it is necessary to assess the severity of the hyperkalemia, whether it is mild, moderate, or severe. For mild hyperkalemia, it can be managed by taking oral diuretics or intravenous infusion of glucose with insulin, which can normalize the potassium level. In cases of severe hyperkalemia, where blood potassium exceeds 7.5 mmol/L, there is a risk of causing cardiac arrest. Emergency measures to promote potassium excretion are required, such as hemodialysis or peritoneal dialysis. It is also necessary to counteract the myocardial depressive effects of potassium, which can be managed with the injection of calcium gluconate, along with the intravenous infusion of hypertonic glucose and insulin. (The use of medications should be conducted under the guidance of a doctor.)