Welcome to the CASSA website and all who attended the Cardiology Update and the ECG Quiz. A handout of the ECG Quiz with ECGs and questions was given to the attendees. If you did not receive this handout with 10 ECGs please contact the organizers of the meeting or me.

The Answers:

ECG 1: 3. Complete Heart Block (CHB). Note that the atrial rhythm is sinus at around 80 bpm and the regular ventricular escape rhythm with a RBBB-like morphology is at 30 bpm . There is complete atrio-ventricular (AV) dissociation indicating CHB.

ECG 2: 2. AF with complete heart block. Note that the underlying rhythm is atrial fibrillation and not flutter. The ventricular rate is 42, and it is regular. If this were conducted AF, the ventricular response would be irregular. Hence, it is regular most likely because it is an escape rhythm with no AV conduction i.e. complete AV heart block. Digoxin toxicity must be considered.

ECG 3: 4. Metabolic / electrolyte disorder. The patient had chronic renal failure and hyperkalaemia with a potassium of 8.8. Note that there are no P waves to be seen so this in not complete heart block. The QRS complexes are uniformly markedly wide which is typical of hyperkalaemia.

ECG 4: 4 . Refer for pacemaker implant because of AVNode dysfunction. The ECG shows sinus bradycardia and AV node Wenckebach 2⁰ AV block. 2⁰ AV block of any kind in elderly persons or patients with heart disease does not have a benign prognosis and should be paced.

ECG 5: 3. May be associated with lethal ventricular tachyarrhythmias. Note that this ECG shows a sinus bradycardia of 42 with normal AV conduction and normal QRS complexes but a markedly prolonged QT interval of 760ms (normal is up to 460ms) and abnormal T waves with notches best seen in V2. Bradycardias lengthen QT intervals which may predispose the patient to polymorphic ventricular tachycardia or Torsade de pointes, which is a very unstable arrhythmia that may degenerate to ventricular fibrillation: ‘ bradycardia-induced-tachycardia '.

ECG 6: 4. Sinus rhythm with left bundle branch block. Note the sharp rapid initial depolarization in V1-3 typical of LBBB.

ECG 7: 2. Ventricular tachycardia. The ECG shows a regular and wide QRS-complex tachycardia, which is enough to call this tachycardia a ventricular tachycardia (VT). Analysis of the QRS in V1-3 shows a wide initial deflection that is very different to the sharp initial depolarization seen in ECG 6.

ECG 8: 3. Acute myocardial infarction with underlying sinus tachycardia and evidence of atrioventricular block. The sinus rate is around 110bpm with 2:1 AV conduction. Note the P waves superimposed on the T waves; this is seen well in V1.

ECG 9: 2. WPW. Note the short PR interval and the delta waves typical of an accessory pathway giving ‘pre-excited QRS complexes' with delta waves. The delta waves in the inferior leads are negative giving a pseudo inferior infarct pattern. WPW patterns may masquerade as infarction and ventricular hypertrophy and ECGs of these conditions may not be interpretable in the presence of antegrade accessory pathway conduction.

ECG 10: 4. Change / Add medications. The ventricular pacemaker is functioning normally at 60bpm. Of note is the underlying rhythm: this is atrial fibrillation. Despite this AF being associated with complete heart block and no symptoms, it carries the usual risk of thromboembolism. This man has significant risks of stroke: age, diabetes, hypertension. Anticoagulation with warfarin must be considered after assessing risk vs. benefit.

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I hope that you enjoyed that quiz and learnt something new!

Would you like to see more or do more quizzes?