Electrical alternans is seen in –
**Electrical Alternans in Cardiac Arrhythmias**
**Core Concept**
Electrical alternans is a rare and life-threatening cardiac arrhythmia characterized by alternating changes in the amplitude of the QRS complex or T wave in the electrocardiogram (ECG). This phenomenon is often associated with cardiac tamponade, which occurs when fluid accumulates in the pericardial space, compressing the heart and impeding its function.
**Why the Correct Answer is Right**
Electrical alternans occurs due to the swinging motion of the heart within the fluid-filled pericardial sac, causing the electrical impulses to vary in intensity. This is often seen in patients with cardiac tamponade, where the increased intrapericardial pressure compromises cardiac output. The swinging motion of the heart is thought to be caused by the pulsatile nature of the cardiac output, which creates a pressure gradient that drives the heart to move within the fluid-filled pericardium.
**Why Each Wrong Option is Incorrect**
* **Option A:** Electrical alternans is not typically seen in hypokalemia, which is a condition characterized by low potassium levels. While hypokalemia can cause arrhythmias, it is not directly associated with electrical alternans.
* **Option B:** Cardiac hypertrophy is a condition characterized by thickening of the heart muscle, which can lead to various arrhythmias. However, it is not directly associated with electrical alternans.
* **Option C:** Myocardial infarction can cause various arrhythmias, including ventricular fibrillation. However, electrical alternans is not a characteristic feature of myocardial infarction.
**Clinical Pearl / High-Yield Fact**
Electrical alternans is a critical sign that requires prompt recognition and treatment, as it is often associated with cardiac tamponade, a life-threatening condition that requires immediate pericardiocentesis.
**Correct Answer:** C. Cardiac tamponade.