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The Ventricular Intracardiac Unipolar Paced‐Evoked Potential in an Isolated Animal Heart
Author(s) -
ECONOMIDES APOLLO P.,
WALTON CHRISTOPHER,
GERGELY STEPHEN
Publication year - 1988
Publication title -
pacing and clinical electrophysiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.686
H-Index - 101
eISSN - 1540-8159
pISSN - 0147-8389
DOI - 10.1111/j.1540-8159.1988.tb04542.x
Subject(s) - medicine , intracardiac injection , stimulus (psychology) , cardiology , evoked potential , heart rate , waveform , electrocardiography , electrophysiology , audiology , biomedical engineering , anesthesia , voltage , blood pressure , psychology , physics , quantum mechanics , psychotherapist
The endocardial unipolar paced evoked response has excited a great deal of interest due to its possible use in the measurement of the metabolic state of the body and other pacer‐related areas. Although rate‐responsive pacing utilizing this signal has been clinically evaluated, little is known regarding the behavior of the components of this waveform under normal physiological conditions. We have developed an electronic circuit which allows the recording of the evoked response within a few milliseconds of a pacing stimulus of 5 V and 0.5 ms duration being applied using a single unipolar, smooth platinum electrode of 14 mm 2 surface area. The paced evoked response was measured using a total of 20 isolated rabbit heart preparations. Five were run for 8 hours and the remaining fifteen were run for 5 hours. Our results indicate that the waveform components of the evoked response remain stable while the preparation is viable, but that two of the time‐related measurements change with loss of viability. A significant lengthening of the stimulus‐R interval was seen together with a dramatic shortening of the R‐T period. The net result of these changes was an overall reduction of 17% in the complex duration. In addition, we found the H‐T shortening to be a sensitive measure of myocardial integrity. We conclude that the combination of our interface charge elimination circuit and the isolated heart preparation has proved a useful system for the investigation of the paced evoked potential. Furthermore, the loss of myocardial viability has a complex action on this response.