Final answer:
A Third-degree heart block is the correct interpretation of the rhythm strip based on the atrial and ventricular rates, variable PR interval, regular rhythm, and the complete absence of correlation between P waves and QRS complexes.
Step-by-step explanation:
The correct interpretation of the rhythm strip provided by the student is a Third-degree heart block. This diagnosis is supported by several key elements of the rhythm strip, which include:
- Atrial rate of 70 with a regular rhythm and variable PR interval, indicating independent atrial activity.
- Ventricular rate of 40 with a regular rhythm and isolation of escape beats, indicating independent ventricular activity.
- A QRS duration of 0.04 seconds, which is within the normal range yet indicates no related activity to the P waves, highlighting complete dissociation between atrial and ventricular activities.
- P wave and QRS complexes that are unrelated to each other, which is the hallmark of a Third-degree heart block where there is no coordination between the atrial and ventricular contractions.
A Third-degree heart block is a type of arrhythmia where the electrical signals from the atria do not properly conduct to the ventricles. In this condition, the atria and ventricles beat independently of each other. The atrial rate is often normal, but the ventricular rate is slower, usually 40-60 beats per minute, because a subsidiary pacemaker (lower down in the heart) takes over.