13.8.2013(Leads) Flashcards
Location of aVL
-30
Location of aVR
-150
Location of aVF
90
Placement of limb electrodes
Distal to shoulder and hip,not necessarily ankle and wrist
Position when recording ECG
Supine
Upright or sitting position is not equivalent
ECG changes when V1 and V2 are erroneously placed in 2nd intercostal space
Poor R wave progression
r’ waves with T wave inversion in V1 and V2
If the diaphragm is displaced downward as in COPD,deep S waves may be recorded
Use of right sided precordial leads
Dextrocardia
Right ventricular hypertrophy
Right ventricular MI
Routinely measure if there is ST elevation in inferior leads
Lewis lead
Rt arm electrode is moved to rt 2nd ICS
Lt arm electrode is moved to rt 4th ICS
Lead 1 is measured
When is a Lewis lead used
When P waves are difficult to visualise
Fontaine lead
Rt arm electrode is moved to manubrium
Lt arm electrode is moved to xiphisternum
Use of Fontaine lead
To detect epsilon waves in arrythmogenic right ventricular dysplasia
Lead 1,2,3 are used for measurement
Normal QRS axis in newborns upto 6months
+90
Normal axis in adults
+90 to -30
Lead 1 is perpendicular to
aVF
Lead 2 is perpendicular to
aVL
Lead 3 is perpendicular to
aVR
R wave taller than S wave is normal in
Children
Causes of tall R waves in V1
RBBB Right ventricular hypertrophy WPW Straight posterior MI Pacemaker rhythm Ventricular ectopic impulses
Right ventricular hypertrophy
Rt axis deviation
Tall R waves in V1
Tall R waves in V1 in WPW
Bypass tract is left sided
Ventricular ectopic impulses showing tall R wave in V1
Impulse originates from lt ventricle
Pacemaker QRS
Rt ventricular pacing- QS or rS in V1
Biventricular pacing- R or Rs in V1
Causes of clockwise rotation of heart
Left ventricular hypertrophy
Rt ventricular hypertrophy in MS,PHT,COPD
COPD
biventricular hypertrophy
Acute pulmonary embolism
Left anterior fascicular block
Cardiac rotation due to mediastinal shifts,pectus excavatum
