Which of the following is the most common arrhythmia: September 2007
**Core Concept**
The most common arrhythmia is a type of abnormal heart rhythm that affects a significant portion of the population, often resulting from various underlying conditions such as hypertension, heart disease, or age-related changes.
**Why the Correct Answer is Right**
The correct answer is sinus tachycardia, which is characterized by an elevated heart rate in the range of 100-160 beats per minute. This condition is often caused by stress, anxiety, or underlying medical conditions such as anemia, fever, or cardiac disease. The sinoatrial (SA) node acts as the heart's natural pacemaker, and an increase in sympathetic tone or a decrease in parasympathetic tone can lead to an elevated heart rate.
**Why Each Wrong Option is Incorrect**
**Option A:** Atrial fibrillation is a common arrhythmia, but it is not the most common. It is characterized by an irregular and often rapid heart rhythm originating from the atria.
**Option B:** Ventricular fibrillation is a life-threatening arrhythmia that requires immediate medical attention, but it is not the most common. It is characterized by a rapid and irregular heart rhythm originating from the ventricles.
**Option C:** Supraventricular tachycardia is a type of arrhythmia that can be caused by various factors, including anxiety or underlying heart conditions. However, it is not the most common arrhythmia.
**Clinical Pearl / High-Yield Fact**
The most common arrhythmia, sinus tachycardia, often presents with symptoms such as palpitations, shortness of breath, or chest discomfort, and can be associated with underlying conditions such as hypertension, heart disease, or age-related changes.
**Correct Answer:** A. Sinus tachycardia