Atrioventricular Conduction Abnormalities

Question 1

ECG signature of classic Wenckebach block ?

Answer 1

Progressive lengthening of the PR interval from one beat to the next until a QRS complex is dropped.

Question 2

Three key features of an ECG with Sinus Rhythm and Complete Heart Block

Answer 2

P waves are present, with a relatively regular sinus rate that is typically much faster than the ventricular rate.
QRS complexes are present, with a slow (usually near constant) ventricular rate.
The P waves bear no relation to the QRS complexes; thus, the PR intervals are variable.

Question 3

Some characteristics of nodal block ?

Answer 3

Often caused by reversible factors, progresses slowly, if at all, in the case of complete heart block, is associated with a relatively stable escape rhythm.

Question 4

Some characteristics of infranodal block ?

Answer 4

Usually irreversible, may progress rapidly and unexpectedly to complete heart block with a slow,unstable escape mechanism, therefore even second-degree infranodal block generally requires pacemaker implantation.

Question 5

What is the classical WPW triad ?

Answer 5

Shortened PR interval (often but not always to less than 120 ms), Widened QRS complex often accompanied by T waves of opposite polarity in any lead, Slurred or notched upstroke of the QRS complex (delta wave).