Electrophysiologic backround for ECG evaluation

Prof. J. Hanáček, MD, PhD

Physiologic ECG curve – its parts

Standard bipolar and augmented unipolar leads

ECG record from standard limb leads

Precordial leads

Scheme of horizontal cut of chest with projection of chest

leads and direction of atrial and ventricular depolarisation

Calculation of heart rate from ECG curve

Evaluation of ECG curve

1) Basic information on the patient –age gender, reason for recording ECG, preliminary Dg

2) Technical parameters of ECG curve – speed of recording,

sensitivity of recording device

3) Date and time of ECG recording

Calculation of heart rate

Electric axis of a heart

Factors which influence electric axis of hart

How to create electric axis of a heart – lead I

How to create electric axis of a heart – lead I and aVF

Left axis deviation

Right axis deviation

Description QRS complex deflections

Heart rhythms

• Sinus rhythm• Atrial rhythm• Junctional rhythm (atrio-ventricular)• Ventricular rhythm

● Heart rhythm is not heart rate, is not regularity of heart function

● Heart rhythm means localisation of source of electrical impuls for activation of heart

Sinus rhythm

- heart function ic controled by sinus node activity

Characteristics of sinus rhythm:

- There should be P wave in front of QRS complex

- P wave is negativ in aVR lead and positive in aVF lead

- P wave should have normal duration and shape

Junctional rhythm

- Polarity of P wave is changed

-Localisation of P wave is also changed

Passive ventricular depolarisation – escape beat

Simple guide for ECG evaluation

- In ECG curve is hidden a lot of important information useful for understanding heart function under physiologic and pathologic conditions

- To find this informations you should have appropriate knowledge and ability to observe carefully the ECG

curve

- For good result of ECG curve evaluation is necessary to evaluate it systematically – using some type of

algorhythm

1) Characteristics of patient – age, gender, date of ECG record was done

preliminary diagnosis, other informations on patient

2) To control technical quality of ECG record, speed of ECG record, sensuitivity of recording device (inappropriate contact of

electrodes with the skin, interference of electricity, other

3) Evaluation frequency of QRS complexes, P waves

4) Evaluation of heart rhythm

5) Evaluation of heart axis

6) Evaluation of separate waves, deflections, segments and intervals

7) Each abnormality should be taken into accont