Keynote Message

To obtain a high level of interpretive skills in the diagnostic approach to difficult electrocardiograms requires the use of a systematic approach, deductive reasoning, information assimilation, and mechanistic hypotheses. Consequently, to master these processes necessitates careful examination of many electrocardiograms, reading not only about electrocardiography but electrophysiology (including cellular electrophysiology), and discussions with others who are practiced in ECG analysis. One of the most important learning tools to master difficult electrocardiograms is to take the time necessary to carefully examine the individual beats as well as the patterns of the heart beating. It is not possible to become skilled in this field by rapid scanning of the recording during a busy clinic day. Careful and methodical examination with investigation cannot be replaced. Learning the language of advanced electrocardiography/electrophysiology would include becoming familiar with terms that reflect mechanism (e.g., gap phenomenon, AV dissociation, concealed conduction, decremental conduction, electrotonic potentials, supernormal conduction, QT:TQ restitution, exit block). Additionally, one of the most important factors to understand during the interpretation of electrocardiograms is the influence of the sympathetic and parasympathetic system, not only on arrhythmias, but also on the patterns of sinus node function. During this session, example electrocardiograms and Holter recordings will be used to illustrate these and other points in the interpretation of difficult electrocardiograms. Focused learning for each tracing will be emphasized.

Key References

1.  Fossa AA. Assessing QT prolongation in conscious dogs: validation of a beat-to-beat method. Pharmacol Ther. 2008;119(2):133–140.

2.  Glukhov AV, Hage LT, Hansen BJ, et al. Sinoatrial node reentry in a canine chronic left ventricular infarct model: role of intranodal fibrosis and heterogeneity of refractoriness. Circ Arrhythm Electrophysiol. 2013;6(5):984–94. DOI: 10.1161/CIRCEP.113.000404.

3.  Lou Q, Glukhov AV, Hansen B, et al Tachy-brady arrhythmias: the critical role of adenosine-induced sinoatrial conduction block in post-tachycardia pauses. Heart Rhythm. 2013;10(1):110–118. DOI: 10.1016/j.hrthm.2012.09.012.