The cardiology behind the ECG, Study notes of Cardiology

Download The cardiology behind the ECG and more Study notes Cardiology in PDF only on Docsity!

The cardiology behind the ECG

Ceri Davies MD, FRCP

Consultant Cardiologist

Barts Health NHS Trust

Objectives

 History of ECG

 Anatomy of the heart

 Understand the electrical basis of the ECG

 Learn how to record an ECG

 Common flaws in ECG acquisition

4 Alexander Muirfield 1848- 1920

5 Augustus Waller (and Jimmy) 1856- 1952

ANATOMY OF THE HEART

8

Self-adhesive pads

3 - lead monitoring

Electrical basis of the ECG

14

Normal ECG waveforms

1 small sq = 0.04 s 1 big sq = 0.2 s PR = 120-200 msec (3-5 small sq) QRS < 120 msec (< 3 small sq) QTc 350-440 msec

12 lead ECG - chest leads

• 6 electrodes → 6 ‘leads’
• V1 = R sternal border, ICS
• V2 = L sternal border, ICS
• V4 = L mid clav line, ICS
• V5 = L anterior ax line, ICS
• V6 = L mid ax line, rib 5
• V3 = Midway between V2+V
• Go over breast tissue

12 lead ECG - limb leads

• 4 electrodes (2 arms, 2 legs) → 6 ‘leads’ (I, II, III, aVR, aVL, aVF)
• The volumetric assumptions work best with big distances
• Wrists and ankles
• R ed = R ight
• “ Green for the spleen”
• R ide Y our G reen B ike Braunwald et al; Heart Disease: A Textbook of Cardiovascular Medicine; WB Saunders ; 2004

20