Studies on the positive T Wave on ECG in the Rat-Based on the Analysis for Direct Cardiac Electrograms in the Ventricle

Jun SUZUKI; Hirokazu TSUBONE; Shigeru SUGANO

doi:10.11276/jsvc1984.26.24

Jun SUZUKI, Hirokazu TSUBONE, Shigeru SUGANO

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Keywords: ECG, electrogram, rat, T wave, ventricular activation

JOURNAL FREE ACCESS

1993 Volume 26 Issue 1 Pages 24-32

DOI https://doi.org/10.11276/jsvc1984.26.24

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Published: 1993 Received: January 27, 1993 Available on J-STAGE: March 05, 2010 Accepted: September 25, 1993 Advance online publication: - Revised: -
Correction information
Date of correction: March 05, 2010 Reason for correction: - Correction: TITLE Details: [in Japanese]

Date of correction: March 05, 2010 Reason for correction: - Correction: ABSTRACT Details: Wrong : In order to obtain direct evidence of the genesis of “positive” T wave on the standard limb lead II electrocardiogram (ECG) in the rat, ventricular activation and its recovery patterns were investigated by recording direct cardiac electrograms. Multiple unipolar electrograms were recorded from 7 sites in the left ventricle including the septum, subendocardium and sube-picardium under the constant sinus rhythms in 12rats. The unipolar electrograms and their differentiated waves were analyzed for local QT intervals and local activation times, respectively. In addition, the direct bipolar electrograms between the subendocardium and the subepicardium of the left ventricle were also recorded in 6 rats. The proceeding times from the septum (initial) to the subepicardium (terminal) were very short as less than 10 msec. Nevertheless, the activation sequence in the left ventricle was clearly shownin accordance to the following order ; the septum, subendocardium and subepicardium. The local QT intervals in the subepicardial sites were significantly shorter than those in the corresponding subendocardial sites (p<0.05). These activation sequences and local QT intervals in the rat ventricle suggest a presence of transmural gradient of depolarization and repolarization, with an earlier depolarization at the endocardium and with an earlier repolarization at the epicardium. Such a transmural gradient might produce an electrical dipole which would contribute to the configuration of positive T wave on the rat ECG. In fact, the positive waves recorded by the direct bipolar electrograms between the subendocardia and the subepicardia can account for the formation of an electrical dipole having a positive charge at the subepicardia against the subendocardia.
Right : In order to obtain direct evidence of the genesis of “positive” T wave on the standard limb lead II electrocardiogram (ECG) in the rat, ventricular activation and its recovery patterns were investigated by recording direct cardiac electrograms. Multiple unipolar electrograms were recorded from 7 sites in the left ventricle including the septum, subendocardium and subepicardium under the constant sinus rhythms in 12rats. The unipolar electrograms and their differentiated waves were analyzed for local QT intervals and local activation times, respectively. In addition, the direct bipolar electrograms between the subendocardium and the subepicardium of the left ventricle were also recorded in 6 rats. The proceeding times from the septum (initial) to the subepicardium (terminal) were very short as less than 10 msec. Nevertheless, the activation sequence in the left ventricle was clearly shownin accordance to the following order ; the septum, subendocardium and subepicardium. The local QT intervals in the subepicardial sites were significantly shorter than those in the corresponding subendocardial sites (p<0.05). These activation sequences and local QT intervals in the rat ventricle suggest a presence of transmural gradient of depolarization and repolarization, with an earlier depolarization at the endocardium and with an earlier repolarization at the epicardium. Such a transmural gradient might produce an electrical dipole which would contribute to the configuration of positive T wave on the rat ECG. In fact, the positive waves recorded by the direct bipolar electrograms between the subendocardia and the subepicardia can account for the formation of an electrical dipole having a positive charge at the subepicardia against the subendocardia.

Date of correction: March 05, 2010 Reason for correction: - Correction: CITATION Details: Wrong : 1) LANGER, G. A. (1978): Variation in myocar-dial physiology: the anomalous rats. Environ. Health. Perspec. 26: 179-185.
2) NAKATA, T., SATOU, S., SEKIYA, S., TSUT-SUMI, K., and NAGATA, H. (1988): The epicardial activation map of the isolated rat heart. Adv. Anim. Cardiol. 21: 27-35.
3) SPEAR, J. F. (1980): Relationship between the scaler electrocardiogram and cellular electrophysiology of the rat heart. pp. 29-40. In: The rat electrocardiogram in pharmacology and toxicology (Budden, R., Detweiler, D. K., and Zbinden, G. eds.) Pergamon Press, Oxford.
4) YAMAMOTO, T., HIROSE, H., and SAWAZAKI,H. (1983): Alternation with age in cardiac activities of rat. Jpn. J. Vet. Sci. 45:53-58.
5) BERNE, R. M. and LEVY, M. N. (1986): Electrical activity of the heart. pp. 5-49. In: Cardiovascular physiology (Berne, R. M. and Levy, M. N. eds.) The C. V. Mosvy Company, St. Louis.
6) CHEN, P., MOSER, K. M., and DEMBITSKY, W. P. (1991): Epicardial activation and repol-arization patterns in patients with right ventricular hypertrophy. Circulation 83: 104-118.
7) FRANZ, M. R., BARGHEER, K., RAFFLENB-EUL, W., and HAVERICH, A. (1987): Monop-hasic action potential mapping in human sub-jects with normal electrocardiograms. Circulation 75: 379-386.
8) SHEPHEND, J. T. and VAUHOUTTE, P. M.(1979): Components of the cardiovascular system: how structure is geared to function. pp. 13-61. In: The human cardiovascular system (Shephend, J. T. and Vauhoutte, P. M. eds.) Raven Press, New York.
9) SPACH, M. S. and BARR, R. C. (1975): Analysis of ventricular activation and repolariza-tion from intramural and epicardial potential distributions for ectopic beat sin the intact dog. Circ. Res. 37: 830-843.
10) SUZUKI, J., TSUBONE, H., and SUGANO, S. (1991): Characteristics of electrocardiographic changes with some representative antiarrhythmic drugs in adult rats. J. Vet. Med. Sci. 53: 779-787.
11) MILLAR, C. K., KRALIOS, F. A., and LUX, R. L. (1985): Correlation between refractory periods and activation-recovery intervals from electrograms: effects of rate and adrenergic interventions. Circulation 72: 1372-1379.
12) SUZUKI, J., TSUBONE, H., and SUGANO, S. (1992): Characteristics of ventricular activation and recovery patterns in the rat. J. Vet. Med. Sci. 54: 711-716.
13) IWA, T. and MUKAI, K. (1983): Epicardial mapping. Medicina Philosophica 2: 257-262.
14) JOSEPHSON, M. E., HOROWITS, L. N., SPIE-LMAN, S. P., WAXMAN, H. L., and GRENSPAN, A. M. (1982): Role of catheter mapping in the preoperative evaluation of ventricular tachycardia. Am. J. Cardiol.49: 206-220.
15) NOBLE, D. (1975): Introduction. pp. 1-16. In. The initiaton of the Heartbeat. Oxford University Press.
16) DURRER, D. R. T., FREUD, G. E., JANSE, M. J., MEIJLER, F. L. and ARZBAECHER, R. C. (1970): Total excitation of the isolated human heart. Circulation 41: 899-912.

Right : 1) LANGER, G. A. (1978): Variation in myocardial physiology: the anomalous rats. Environ. Health. Perspec. 26: 179-185.
2) NAKATA, T., SATOU, S., SEKIYA, S., TSUT-SUMI, K., and NAGATA, H. (1988): The epicardial activation map of the isolated rat heart. Adv. Anim. Cardiol. 21: 27-35.
3) SPEAR, J. F. (1980): Relationship between the scaler electrocardiogram and cellular electrophysiology of the rat heart. pp. 29-40. In: The rat electrocardiogram in pharmacology and toxicology (Budden, R., Detweiler, D. K., and Zbinden, G. eds.) Pergamon Press, Oxford.
4) YAMAMOTO, T., HIROSE, H., and SAWAZAKI,H. (1983): Alternation with age in cardiac activities of rat. Jpn. J. Vet. Sci. 45:53-58.
5) BERNE, R. M. and LEVY, M. N. (1986): Electrical activity of the heart. pp. 5-49. In: Cardiovascular physiology (Berne, R. M. and Levy, M. N. eds.) The C. V. Mosvy Company, St. Louis.
6) CHEN, P., MOSER, K. M., and DEMBITSKY, W. P. (1991): Epicardial activation and repolarization patterns in patients with right ventricular hypertrophy. Circulation 83: 104-118.
7) FRANZ, M. R., BARGHEER, K., RAFFLENB-EUL, W., and HAVERICH, A. (1987): Monophasic action potential mapping in human subjects with normal electrocardiograms. Circulation 75: 379-386.
8) SHEPHEND, J. T. and VAUHOUTTE, P. M.(1979): Components of the cardiovascular system: how structure is geared to function. pp. 13-61. In: The human cardiovascular system (Shephend, J. T. and Vauhoutte, P. M. eds.) Raven Press, New York.
9) SPACH, M. S. and BARR, R. C. (1975): Analysis of ventricular activation and repolarization from intramural and epicardial potential distributions for ectopic beat sin the intact dog. Circ. Res. 37: 830-843.
10) SUZUKI, J., TSUBONE, H., and SUGANO, S. (1991): Characteristics of electrocardiographic changes with some representative antiarrhythmic drugs in adult rats. J. Vet. Med. Sci. 53: 779-787.
11) MILLAR, C. K., KRALIOS, F. A., and LUX, R. L. (1985): Correlation between refractory periods and activation-recovery intervals from electrograms: effects of rate and adrenergic interventions. Circulation 72: 1372-1379.
12) SUZUKI, J., TSUBONE, H., and SUGANO, S. (1992): Characteristics of ventricular activation and recovery patterns in the rat. J. Vet. Med. Sci. 54: 711-716.
13) IWA, T. and MUKAI, K. (1983): Epicardial mapping. Medicina Philosophica 2: 257-262.
14) JOSEPHSON, M. E., HOROWITS, L. N., SPIE-LMAN, S. P., WAXMAN, H. L., and GRENSPAN, A. M. (1982): Role of catheter mapping in the preoperative evaluation of ventricular tachycardia. Am. J. Cardiol.49: 206-220.
15) NOBLE, D. (1975): Introduction. pp. 1-16. In. The initiaton of the Heartbeat. Oxford University Press.
16) DURRER, D. R. T., FREUD, G. E., JANSE, M. J., MEIJLER, F. L. and ARZBAECHER, R. C. (1970): Total excitation of the isolated human heart. Circulation 41: 899-912.

Abstract

In order to obtain direct evidence of the genesis of “positive” T wave on the standard limb lead II electrocardiogram (ECG) in the rat, ventricular activation and its recovery patterns were investigated by recording direct cardiac electrograms. Multiple unipolar electrograms were recorded from 7 sites in the left ventricle including the septum, subendocardium and subepicardium under the constant sinus rhythms in 12rats. The unipolar electrograms and their differentiated waves were analyzed for local QT intervals and local activation times, respectively. In addition, the direct bipolar electrograms between the subendocardium and the subepicardium of the left ventricle were also recorded in 6 rats. The proceeding times from the septum (initial) to the subepicardium (terminal) were very short as less than 10 msec. Nevertheless, the activation sequence in the left ventricle was clearly shownin accordance to the following order ; the septum, subendocardium and subepicardium. The local QT intervals in the subepicardial sites were significantly shorter than those in the corresponding subendocardial sites (p<0.05). These activation sequences and local QT intervals in the rat ventricle suggest a presence of transmural gradient of depolarization and repolarization, with an earlier depolarization at the endocardium and with an earlier repolarization at the epicardium. Such a transmural gradient might produce an electrical dipole which would contribute to the configuration of positive T wave on the rat ECG. In fact, the positive waves recorded by the direct bipolar electrograms between the subendocardia and the subepicardia can account for the formation of an electrical dipole having a positive charge at the subepicardia against the subendocardia.

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