True regarding 2nd degree hea block:
High-Yield Explanation
In 2nd degree hea block - some of the SA nodal impulses do reach the ventricles whereas some are not able to reach the ventricles. Consequently, ventricular rate is slower than the atrial rate. 3rd degree hea block is called the complete hea block, when no impulse from SA node reaches the ventricles. Since ventricles remain quiescent for a while, it results in dizziness followed by syncope - Stokes Adam's syndrome.