The T-wave, Anger, and Arrhythmias

For the layman, an EKG is a series of repeated blips. Interpretation is limited to many beeps = good. No beeps = bad. Fortunately, the clinician can glean a great deal more information from those series of beeps and lines on a chart.

One of the breakthroughs of Einthoven (whom we discussed earlier for his Nobel prize win for EKG machine technology) is that he assigned the letters P, Q, R, S and T to the various deflections of the EKG tracing. It is the T wave, the last part of the cycle, that has great diagnostic value. And according to a new study released in the February 24, 2009 online edition of the Journal of the American College of Cardiology (J Am Coll Cardiol, 2009; 53:774-778,) changes in the T wave may have even greater predictive value in the future. This study is receiving a lot of coverage because with heart disease a major cause of death in the U.S., there is always a need for a better way to diagnose the problem.

First a bit of background: the T wave represents the re-polarization of the ventricles, the part of the heart that sends the blood into the lungs (right ventricle) or out to the body (left ventricle). This re-polarization is vital so that the heart can “reset” and get ready for the wave of stimulation to begin again for the next heartbeat.

What is very important is a T wave phenomenon called the T wave alternans or TWA. This is a periodic variation from beat to beat in the amplitude of the T wave. If too many TWAs are detected, the patient is at greater risk for developing a potentially lethal cardiac arrhythmia and sudden death. Patients with increased TWAs become good candidates for pacemakers.

The study referenced above, led by Dr. Rachel Lampert, MD, FACC, showed that when an anger inducing stimulus was presented to test subjects, they exhibited TWAs. This parallels the induction of TWAs by exercise in other studies. Her team also showed an 11 fold increase in the need to implant pacemakers in patients who showed anger-induced TWAs.

While this could ultimately lead to a new way to predict future arrhythmias in patients, Dr. Lampert had only 62 subjects in this study. She cautions that the study data should be considered preliminary and should only be used to generate hypotheses. Still it will be interesting to see if this adds a new dimension to the diagnostic utility of the ubiquitous EKG machine.

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