ECG 3 chapters 1–7:Layout 1 10/09/2014 11:08 Page 21
Heart blocks
Figure 4.4: Third degree (complete) heart block. Note that there are regular P waves (blue arrows) and there are also regular QRS complexes (red arrows) but there is no relationship between them.
SUMMARY: Heart blocks Is the relationship between the atrial and ventricular activity normal on the ECG strip? If not, could it be a type of heart block? Which pattern does it fit? First degree
PR interval > 0.20 seconds
Second degree ●
Mobitz type I (Wenkebach)
PR gradually gets longer and then drops a beat.
●
Mobitz type II
Dropped beats but PR interval before the QRS complexes are always constant.
Third degree
No relationship between atrial and ventricular activity.
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