A patient develops sudden palpitation with HR 150/ min, regular. What could be the cause
**Core Concept**
The patient's symptoms, sudden palpitation with a regular heart rate of 150/min, are indicative of a supraventricular tachycardia (SVT). SVT is a type of abnormally fast heart rhythm originating from the atria or the atrioventricular (AV) node. This condition is characterized by a rapid and regular heart rate, often exceeding 100 beats per minute.
**Why the Correct Answer is Right**
The correct answer is likely related to a re-entry circuit in the AV node or a bypass tract. In SVT, an abnormal electrical pathway, such as the AV node or a bypass tract like the Wolff-Parkinson-White (WPW) syndrome, allows the electrical impulse to re-enter the atria prematurely, triggering a rapid and regular heart rate. This can be triggered by various factors, including stress, caffeine, or certain medications.
**Why Each Wrong Option is Incorrect**
* **Option A:** This could be a cause of tachycardia, but it is not the most likely cause of a sudden onset of a regular heart rate of 150/min. Atrial fibrillation is a type of irregular heart rhythm, not a regular one.
* **Option B:** This is not a direct cause of tachycardia. Hypokalemia can lead to various cardiac arrhythmias, but it is not the most likely cause of a sudden onset of a regular heart rate of 150/min.
* **Option C:** This is not a direct cause of tachycardia. Hyperthyroidism can lead to tachycardia, but it is typically a more gradual onset of symptoms, not a sudden onset of a regular heart rate of 150/min.
**Clinical Pearl / High-Yield Fact**
A key point to remember is that SVT often presents with a regular heart rate, whereas other types of tachycardia, such as atrial fibrillation, typically present with an irregular heart rate. Recognizing the regularity of the heart rate is crucial in diagnosing SVT.
**Correct Answer:** .