ECG Case 029
Asymptomatic 40-year old patient. Describe the ECG.
Describe and interpret this ECG
ECG ANSWER and INTERPRETATION
- Irregular narrow-complex rhythm (overall rate = 72 bpm)
- Normal sinus P waves are seen (upright in lead II), indicating a sinus origin of the rhythm
- QRS complexes cluster in groups, separated by non-conducted P waves
- The PR interval progressively prolongs within each group
- The PR prolongation can be appreciated by comparing the first and last PR interval of each group
This is the typical appearance of 2nd degree AV block with Mobitz I conduction (Wenckebach phenomenon).
In comparison to patients with Mobitz II, who typically require a pacemaker for prophylaxis of complete heart block and ventricular standstill, patients with Mobitz I do not necessarily need any intervention.
This is provided that they are asymptomatic with a normal BP, and that reversible causes such as drug toxicity (beta-lockers, digoxin), hyperkalaemia and myocardial ischaemia have been excluded.
The risk of progression to haemodynamically unstable AV block in these patients is very low.
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Emergency Physician in Prehospital and Retrieval Medicine in Sydney, Australia. He has a passion for ECG interpretation and medical education | ECG Library |
MBBS (UWA) CCPU (RCE, Biliary, DVT, E-FAST, AAA) Adult/Paediatric Emergency Medicine Advanced Trainee in Melbourne, Australia. Special interests in diagnostic and procedural ultrasound, medical education, and ECG interpretation. Editor-in-chief of the LITFL ECG Library. Twitter: @rob_buttner