Resuscitation Council UK (RCUK) Advanced Life Support (ALS) Practice Exam

Ventricular fibrillation is a critical condition characterized by disorganized electrical activity in the heart, leading to ineffective pumping and loss of consciousness. One of the key factors that can lead to this arrhythmia is an abnormal potassium concentration, particularly hypokalemia (low potassium levels) or hyperkalemia (high potassium levels). Potassium is crucial for maintaining normal cardiac excitability and conduction; imbalances can disrupt the action potentials of cardiac myocytes, predisposing individuals to arrhythmias like ventricular fibrillation.

In the context of cardiac function, potassium abnormalities can change the membrane potential and refractory period of myocardial cells, leading to increased automaticity and ectopic foci, which can trigger ventricular fibrillation. Therefore, recognizing and correcting abnormal potassium levels is essential in managing patients at risk of this dangerous arrhythmia.

Other options may not have the same direct and immediate impact on the risk of ventricular fibrillation. For instance, hyperthyroidism primarily affects metabolism and can lead to various cardiovascular effects, but it is not directly linked to acute arrhythmias like ventricular fibrillation in the same way that potassium imbalances are. Oligemia relates to reduced blood volume, which can affect perfusion but does not directly cause electrical disturbances in the heart. Hyper