P wave in Sinus Tachycardia

 Q: In Sinus Tachycardia, the P wave is inverted (negative) in lead? (select one)

A) I 

B) II 

C) aVL 

D) aVR

Answer: D

It is very important to distinguish sinus tachycardia from other forms of tachycardia at the bedside. Sinus tachycardia may be merely a physiologic response to a wide variety of clinical conditions including fever, volume depletion, sepsis, anemia, hypoxia, PE, coronary ischemia, pain, anxiety, hyperthyroidism, drugs, and others. 

By definition, sinus tachycardia is determined by three basic criteria 

• Heart Rate above 100, 
• Rhythm regular
• Normal P vector 

The best way to establish a normal P vector is by confirming positive (upright) P waves in leads I, II, and aVL, and a negative (inverted) P wave in lead aVR.

#cardiology

References:

1. Becker DE. Fundamentals of electrocardiography interpretation. Anesth Prog. 2006;53(2):53-64. doi:10.2344/0003-3006(2006)53[53:FOEI]2.0.CO;2 

2. Noble RJ, Hillis JS, Rothbaum DA. Electrocardiography. In: Walker HK, Hall WD, Hurst JW, editors. Clinical Methods: The History, Physical, and Laboratory Examinations. 3rd edition. Boston: Butterworths; 1990. Chapter 33. Available from: https://www.ncbi.nlm.nih.gov/books/NBK354/