Summary

Terminology used in clinical electrocardiography includes terms: the “baseline” (or the T-P interval) – which is accepted to be stable, (or made so by the type of amplifiers used in the clinical recorders), of zero voltage, and then the J- point and ST-segments shifts, (in relation to this stabilazed baseline), which correlate well with various types of clinical pathology and have a definite clinical significance. On the other hand, certain types of amplifiers used in the experimental work in laboratories, may introduce “drifting of the baseline” (requiring constant correcting to allow successful recording), which is caused by the “polarization effect” currents which develop at the interface between the metal components of the recording electrodes and the live tissue, body fluids and electrolyte content and concentration. We became interested in these phenomena and decided to try to determine, if there exist a “true” baseline shifts – in relation to a stable D.C. (direct current) zero voltage baseline – and what are in reality the “true” J-point and ST-segment shifts recorded in clinical electrocardiography.

Pilot experiments were carried out on the exposed hearts of anesthetized rabbits and dogs using laboratory type calomel electrodes and D.C. amplifiers. Bipolar epicardial leads were recorded. The same type of electrode was used as a distant “grounding” electrode. Interventions included local application of potassium and sodium solutions and induction of local myocardial ischemia by ligation of small coronary artery branches.

True baseline shifts were observed, in both directions (positive or negative), alone or with the J-point and ST-segment shifts, in opposite direction. They were most pronounced after local application od potassium solution or severe local ischemia. Examples of recordings are shown below and observations are summarized in the Table. No attempt was made in these limited series of experiments to elucidate the mechanism for creating these voltage differentials between the baseline (T-P segment), the ST segment and the zero D.C. baseline. It remains to be determined, if this type of differentiation provides any new type of information, carries any clinical significance or could be correlated with the type or degree of clinical pathology.

1. A Method for Experimental Recording of the D.C. and Very Low Frequency Components of the Electrocardiogram. Waldemar J. Wajszczuk and Józef  K. Cywinski. Engineering in Medicine and Biology, Proceedings of the 19^th Annual Conference, San Francisco, CA, 17 November, 1966, p. 245.

2. The recording of d.c. and very low frequency components of ECG signals from epicardial leads. Józef K. Cywiński and Waldemar J. Wajszczuk

Medical and Biological Engineering and Computing, Volume 4, Number 2 / March, 1966

http://springerlink.com/content/?k=Wajszczuk; https://commerce.metapress.com/content/58087405p5370075/resource-secured/?target=fulltext.pdf&sid=nbw12255rarcz3jdln4y4h55&sh=springerlink.com;

(https://springerlink3.metapress.com/content/58087405p5370075/resource-secured/?target=fulltext.pdf&sid=fezt2z45iyr3d355cgdmpq55&sh=www.springerlink.com)

http://www.springerlink.com/content/58087405p5370075/

Abstract. By means of the calomel electrode technique described and the use of d.c. amplifiers it has been possible to measure and record the very low frequency and d.c. components of ECG signals. These signals can be recorded by means of a commercial electrocardiograph with 50 mV d.c. input terminals, connected to a special preamplifier. Both very low frequency and d.c. components of signals from the epicardium carry information about the heart muscle conditions. These conditions depend, among others, on the electrolyte composition and concentration changes in a zone between two exploring electrodes on the heart muscle.

http://www.ncbi.nlm.nih.gov/sites/entrez

3. Observations on D. C. and Very Low Frequency Components of the Electrocardiogram.

Waldemar J. Wajszczuk and Józef K. Cywinski. Exp. Biol. Med. 123(1): 42—47; Volume 123 Number 1, October 1966

http://ebm.rsmjournals.com/content/vol123/issue1/