Approach to ECG Interpretation 2004.9.22.

InterpretationHeart rate P wave Origin of the rhythm PR interval QRS duration QT interval QRS axis QRS voltage Precordial R wave progression Abnormal Q wave ST segment T wave U wave Electronic pacemaker

Heart RateRegular rhythmHR=300no. large boxes between R wave (assumes a standard paper speed of 25mm/s) It is easier to memorize the heart rate associated with each of the large boxes. (30015010075 60504337)

Heart RateSlow or Irregular RhythmIdentify the 3-second markers at top or bottom of ECG tracing Count the number of QRS complexes that appear in 6 seconds Multiply by 10 to obtain rate in BPM

P WaveP waveElectrical forces generated from atrial activation. The first and second halves of the P wave roughly correspond to right and left atrial activation, respectively.

What to measureDuration (seconds) Amplitude (mm)

P WaveNormal P wave characteristicsDuration: 0.08-0.11 seconds Axis: 0-75 Morphology:Upright in I,II,aVF Upright or biphasic in III,aVL,V1,V2

Amplitude:Limb leads: