Case 7

This case was provided by Mark Santamaria

Stem: This is the tracing of a 70 year old woman with a past history of myocardial infarction. She presents with palpitations and dizziness

+ List the significant findings in the ECG, and provide the most important or likely diagnosis

  • The rhythm is irregular, with grouping of the complexes in the rhythm strip
  • The first two complexes in the rhythm strip show a sinus rhythm, with a rate of about 30 beats per minute. The underlying atrial rhythm is sinus bradycardia
  • The third to fifth complexes in the rhythm strip are consecutive atrial ectopic beats, with a R-R interval of 640 msec between the ectopic beats (this corresponds to a rate of about 94 beats per minute). The seventh complex in the rhythm strip is a single atrial ectopic - the preceding P wave is not visible in the rhythm strip but is seen near the tip of the T wave in Leads V1 to V3
  • The PR interval of the sinus beats is prolonged (at about 0.32 seconds) i.e. there is first degree heart block. Left axis deviation is present, as well as right bundle branch block i.e. there is a bifasicular block (or trifasicular block if we include the first degree heart block)
  • The QT interval is prolonged at about 600 msec
  • The QRS complexes in the chest leads are all upright i.e. positive concordance is present
  • The QRS voltages are consistent with left ventricular hypertrophy
  • Pathological Q waves are present in the anterolateral leads. J point depression and T wave inversion is present in Leads 1 and aVL
  • J point depression is present in Leads V2 to V6
  • The T waves are inverted in Leads V1 to V3, with the downslope longer than the upslope - these are probably secondary T wave changes
  • The T waves in Leads V4 to V6 are upright, with the T waves in Leads V5 and V6 being more symmetric suggesting ischaemia.

There are multiple abnormalities which can be grouped on their (likely) clinical significance:
A. Conduction problems: sinus bradycardia, first degree heart block, left axis deviation and right bundle branch block.
B. Prolonged QT interval
C. Possible acute cardiac ischaemia based on the T inversion in Leads I and aVL and the T wave morphology in Leads V5 and V6 (as well as J point depression in these leads)
D. Atrial ectopic beats- single and in salvoes
E. Not immediately relevant: left ventricular hypertrophy, Q waves in the anterolateral leads, positive concordance ( a supraventricular tachycardia in this patient would produce a broad complex tachycardia with positive concordance - if there was no previous ECG for comparison the presence of concordance would be in favour a diagnosis of ventricular tachycardia)