Effects of Experimental Regional Ischemia and Levarterenol on the RS‐T Segment and Baseline of Ventricular Surface Electrocardiograms Obtained by Direct‐Coupled Amplification

Conventional electrocardiographie equipment (capacitance-coupled amplification) cannot distinguish between RS-T segment and baseline shifts of the ventricular complex. The so-called RS-T segment displacement is the net difference between the undetermined levels of those components. Using direct-coupled amplification, the absolute changes of baseline and RS-T segment on the surface of the exposed left ventricle during levarterenol administration and during regional ischemia, and release-recovery were studied in dogs. Ten significant patterns of displacement were observed. These permitted clear differentiation of the effects of levarterenol injection and hyperperfusion from those of ischemia. The centers and borders of an ischemic area could be distinguished and the change with prolonged ischemia described. The relationship of these observations to the literature and pertinent studies of intracellular action potentials are discussed.

[1]  F. N. Wilson,et al.  Form of the Electrocardiogram in Experimental Myocardial Infarction , 1933 .

[2]  W. Gilson,et al.  POTENTIAL CHANGES IN AN INJURED REGION OF CARDIAC MUSCLE , 1938 .

[3]  R. Bayley,et al.  Electrocardiographic changes (local ventricular ischemia and injury) produced in the dog by temporary occlusion of a coronary artery, showing a new stage in the evolution of myocardial infarction , 1944 .

[4]  E. Starling,et al.  V. On the electromotive phenomena of the mammalian heart , 1892, Proceedings of the Royal Society of London.

[5]  F. N. Wilson,et al.  The form of the electrocardiogram in experimental myocardial infarction , 1935 .

[6]  V. ALZAMORA-CASTRO,et al.  The electrical manifestations observed in damaged or injured cardiac muscle; an experimental study. , 1957, American heart journal.

[7]  R. Pruitt,et al.  The immediate electrocardiographic effects of circumscribed myocardial injuries; an experimental study. , 1948, American heart journal.

[8]  S. Bellet,et al.  Negative displacement of the RS-T segment in the electrocardiogram and its relationship to positive displacement; an experimental study. , 1945, Archivos del Instituto de Cardiologia de Mexico.

[9]  S. Weidmann,et al.  Effects of calcium ions and local anaesthetics on electrical properties of Purkinje fibres , 1955, The Journal of physiology.

[10]  F. N. Wilson,et al.  The interpretation of the galvanometric curves obtained when one electrode is distant from the heart and the other near or in contact with the ventricular surface: Part II. Observations on the mammalian heart , 1934 .

[11]  J. Dudel,et al.  [The action current of the myocardial fibers in oxygen deficiency]. , 1954, Pflugers Archiv fur die gesamte Physiologie des Menschen und der Tiere.

[12]  F. N. Wilson,et al.  Monophasic Electrical Response Produced by the Contraction of Injured Heart Muscle , 1933 .

[13]  R. Bing,et al.  The Effect of Complete Ischemia on the Intracellular Electrical Activity of the Whole Mammalian Heart , 1958, Circulation research.

[14]  A. Katcher,et al.  The Effect of Levarterenol on Polarographic Myocardial Oxygen, the Epicardial Electrocardiogram and Contraction: in Nonischemic Dog Hearts and Experimental Acute Regional Ischemia , 1960, Circulation research.

[15]  J. Burdon-Sanderson.  On the Time‐Relations of the Excitatory Process in the Ventricle of the Heart of the Frog , 1880 .

[16]  L. Katz,et al.  OBSERVATIONS ON THE GENESIS OF THE ELECTRICAL CURRENTS ESTABLISHED BY INJURY TO THE HEART , 1940 .

[17]  L. Rakita,et al.  Studies on the mechanism of ventricular activity. XII. Early changes in the RS-T segment and QRS complex following acute coronary artery occlusion: experimental study and clinical applications. , 1954, American heart journal.

[18]  G. Peirce,et al.  Polarographic Oxygen, the Epicardial Electrocardiogram and Muscle Contraction in Experimental Acute Regional Ischemia of the Left Ventricle , 1958, Circulation research.

[19]  A. Ekmekci,et al.  Angina pectoris: III. Demonstration of a chemical origin of ST deviation in classic angina pectoris, its variant form, early myocardial infarction, and some noncardiac conditions∗ , 1959 .

[20]  F. N. Wilson,et al.  The interpretation of the galvanometric curves obtained when one electrode is distant from the heart and the other near or in contact with the ventricular surface , 1934 .