ecg basics conduction tissue

Dr. Md.Toufiqur Rahman MBBS, FCPS, MD, FACC, FESC, FRCP,

FSCAI, FAPSIC, FAPSC

Associate Professor of CardiologyNational Institute of Cardiovascular Diseases

Sher-e-Bangla Nagar, Dhaka-1207

Dr. Md.Toufiqur Rahman MBBS, FCPS, MD,FACC, FESC, FRCP, FSCAI, FAPSIC, FAPSC

Conduction Tissue

Normal Rhythm ECG

Leads of ECG

Precordial Leads

Pathology of conduction tissue

Sinoatrial block

• Sinus rhythm for three beats, then a 'sinus pause'• P waves arrowed• The expected P wave is not seen, but the SA node must have beendepolarized because the next P wave appears at the predicted time

First degree block

• Sinus rhythm• PR interval is constant (360 ms)

Second degree block (Mobitz type 2)

• Sinus rhythm with a normal PR interval• One P wave (arrowed) is not followed by a QRS complex

Second degree block (Wenckebach)

• Three beats with progressively longer PR intervals are followed by a non-conducted P wave (arrowed)• The next PR interval is short, but this is followed by a longer PR interval and then another non-conducted beat

Second degree block (2:1)

• The conducted beats have a normal PR interval• Alternate P waves are not followed by a QRS complex;

Complete (third degree) block

• No relationship between P waves (arrowed) and QRS complexes• The QRS complexes are normal, indicating that the origin of ventricular depolarization is within the His bundle• The ventricular rate is 30/min

Complete (third Degree) block

• No relationship between P waves (arrowed) and QRS complexes• Wide QRS complexes• Ventricular rate of 22/min

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