Cardiac-Vascular Nursing (CVRN) Practice Exam

What is the greatest risk within the first 24 hours of sustaining a myocardial infarction?

1. Heart failure

2. Pulmonary embolism

3. Ventricular aneurysm

4. Ventricular fibrillation

The correct answer is: Ventricular fibrillation

In the first 24 hours after a myocardial infarction (MI), the greatest risk is ventricular fibrillation. Following an MI, the heart muscle can become electrically unstable due to ischemia and necrosis, which increases the likelihood of lethal arrhythmias such as ventricular fibrillation. This condition arises when the electrical signals in the heart become disorganized, leading to ineffective contractions and a failure to pump blood, which can result in sudden cardiac arrest. During this early period after an MI, patients are particularly vulnerable to changes in heart rhythm due to electrolyte imbalances, increased sympathetic stimulation, and ongoing ischemia. Monitoring and immediate intervention are crucial during this timeframe to identify and manage any arrhythmias that may occur. Other risks such as heart failure, pulmonary embolism, or ventricular aneurysm can develop as complications later in the course after the initial event. However, ventricular fibrillation represents the most immediate threat to life within the first day following a myocardial infarction.