Which of the following complications are associated with hyperkalemia?

Hyperkalemia, defined as elevated potassium levels in the blood, has several significant physiological effects on the cardiovascular system. One of the most notable complications is bradycardia, which is a slower than normal heart rate. High levels of potassium can alter cardiac conduction pathways, particularly influencing the activity of the cardiac cells responsible for generating and propagating action potentials. Elevated potassium levels can lead to the delay of conduction and can facilitate more prolonged repolarization of cardiac muscle cells. This results in bradycardia and can lead to serious arrhythmias if not addressed.

In contrast, the other options are not associated with the primary complications of hyperkalemia. Narrow QRS intervals usually indicate a faster conduction, which is contrary to the effects seen with hyperkalemia. Hyperventilation is typically linked to metabolic disorders or respiratory distress but does not have a direct correlation to potassium levels. Lastly, increased blood pressure is not a usual consequence of hyperkalemia; instead, hyperkalemia is more commonly associated with potential decreases in cardiac output and other cardiovascular symptoms.