Advanced Cardiovascular Life Support (ACLS) Practice Exam

What type of tachycardia frequently has a heart rate over 100 beats per minute but is a normal physiological response?

1. Atrial fibrillation

2. Sinus tachycardia

3. Ventricular tachycardia

4. Junctional tachycardia

The correct answer is: Sinus tachycardia

Sinus tachycardia is characterized by an increased heart rate that exceeds 100 beats per minute, which is a common and normal physiological response in various situations. This type of tachycardia typically occurs in response to factors such as exercise, stress, fever, dehydration, or other stimuli, reflecting the body's demand for increased blood flow and oxygen delivery. Unlike atrial fibrillation, which is an irregular and often chaotic heart rhythm that can result in serious complications, or ventricular tachycardia, which originates in the ventricles and can be life-threatening, sinus tachycardia is generated by the heart's natural pacemaker, the sinoatrial (SA) node. Junctional tachycardia, while also originating from the heart's conduction system, usually arises from the atrioventricular (AV) junction and can indicate an underlying pathology. In this context, understanding the physiological basis of sinus tachycardia is crucial, as it demonstrates how the heart can adapt to varying demands placed upon it, contrasting with the other types of tachycardia that may signal an underlying cardiac issue or necessitate urgent medical intervention.