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Health Dictionary

Reliable, easy-to-read patient information on common medical conditions — written in plain language, free of jargon, and grounded in current evidence. Browse the most frequent diagnoses, understand what they mean for everyday life, and learn which steps and questions help you have a focused conversation with your doctor.

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Sinus tachycardia laboratory findings

Introduction

Electrocardiogram

  • Rate: Greater than 100.
  • Rhythm: Regular.
  • P waves: Upright, consistent, and normal in morphology (if no atrial disease)
  • PR interval: Between 0.12–0.20 seconds and shortens with increasing heart rate
  • QRS complex: Less than 0.12 seconds, consistent, and normal in morphology
  • Pathophysiology: Sinus tachycardia is considered “appropriate” when a reasonable stimulus such as fever, anemia, fright, stress, or physical activity, provokes the tachycardia. This is in distinction to Inappropriate sinus tachycardia where no such stiumulus exists.

EKG Examples

Shown below is an EKG example of sinus tachycardia with a heart rate of 125/min. The rhythm is regular.

Copyleft image obtained courtesy of ECGpedia, http://en.ecgpedia.org/wiki/File:Sinustachycardia.jpg

Shown below is an EKG example of 12 lead EKG showing sinus tachycardia. The heart rate is 150 bpm

Copyleft image obtained courtesy of ECGpedia, http://en.ecgpedia.org/wiki/Main_Page