The nurse needs further education and training when the nurse describes Mobitz type I block as:

an unstable rhythm that is usually caused by an ventricle muscle disturbance
first-degree atrioventricular block
the most severe form of heart block that carries a bad prognosis


• Second-degree AV block is a problem with the electrical conduction system in the heart between the atria and the ventricles.

• Mobitz type I heart block, also known as Wenckebach,  involves prolonged PR intervals followed by blocked P waves (this results in a 'dropped' QRS complex). The cycle then repeats. No treatment is indicated unless the patient is experiencing symptoms, however recognizing this rhythm is important because treatment of conduction blocks is based on the type and degree of block.

• Mobitz type I is the mildest form of second-degree heart block and carries a better prognosis compared to second degree Mobitz type II or third degree block (most severe).

• Mobitz type I is a stable rhythm that usually does not result in clinical manifestations because the ventricular rate (heart rate) is typically adequate.

• Mobitz type I is also known as the Wenckebach phenomenon in which the QRS complexes are typically "grouped" into twos, threes, fours, and so on.

• Mobitz type I is a form of second-degree heart block.

• Mobitz type I is caused by a block in the AV node.

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