L06 Electrocardiography II

This BSL lesson explains Einthoven’s triangle and allows the students to record their ECG using bipolar Leads (I, II, and III). The students will attach Leads I and III and the software will calculate Lead II for them, using Einthoven’s law. The system displays the data for all three Leads. The students will perform a number of tasks designed to change the rhythm of the heart. They will analyze the data and calculate the Mean Electrical Axis of the heart.

Experimental Objectives

1. Record ECG from Leads I and III in three conditions: lying down, sitting up, and breathing deeply while sitting.
2. Review the ECG for Lead II.
3. Correlate the direction of the QRS complex (±) with the direction of the Lead axis.
4. Estimate the Mean Electrical Axis of the QRS complex using two methods.

Tasks Performed by the Student

• Record ECG using bipolar Leads I and III
  • Sit and relax.
  • Lie down and relax.
  • Take five deep breaths and mark each event.

Lesson Hardware

This lesson requires a Biopac Student Lab (BSL) System and the following hardware. If your BSL System does not include all hardware items, expand your system by selecting required items below. For more details, review the Lesson: L# BSL Lessons - see the Lab Manual or launch BSL; A# and H# BSL PRO Lessons, click the PDF link above to review full setup, recording, and analysis procedures.