ECG of the Week - 18th December 2017 - Interpretation

The following ECG is from a 90 yr old female who presented with general deterioration, weakness and anorexia. She has a past cardiac history of cardiac failure, paroxysmal atrial fibrillation and aortic valve replacement.

Click to enlarge

Rate:

• Mean ventricular rate 66 bpm 

Rhythm:

• Atrial fibrillation
• Irregular rhythm
• Fibrillation waves sen in leads V2-3
• Single PVC

Axis:

• Extreme

Intervals:

• QRS - Prolonged

Additional:

• Abnormal R wave progression 
• Absent dominant S waves in lateral precordial leads
• Progressive decrease in QRS voltage from lead V1 to V6
• Very high voltage lead V1
• Dominant R with massive S wave

This ECG is challenging as there are a number of abnormalities including:

• Rhythm abnormality
• AF
• Conduction abnormality
• QRS prolongation & fragmentation
• Reflecting underlying IHD & cardiomyopathy

What about the precordial leads ?

This patient also has dextrocardia, as evidenced by the abnormalities in R wave progression thorough out the precordial leads, This is difficult to spot as the absence of P waves and abnormal QRS conduction make the other features of dextrocardia (completely negative lead I and positive lead aVR) almost impossible to pick.
The ECG was repeated with mirrored right sided ECG, shown below. The precordial leads are placed on the right hemithorax mirroring their usual placement and the limb leads are reversed i.e. RA / LA are swapped and RL / LL are swapped.

Click to enlarge

The repeat ECG shows persistent AF with correction of the abnormal axis (extreme to borderline LAD) seen in the first ECG in addition to normal R wave progression throughout the precordial leads. The ECG now also has voltage criteria for LVH which wan't appreciable before.

References / Further Reading

Life in the Fast Lane

• Dextrocardia
• Atrial Fibrillation
• LVH

Textbook

• Chan TC, Brady WJ, Harrigan RA, Ornato JP, Rosen P. ECG in Emergency Medicine and Acute Care. Elsevier Mosby 2005.