Normal Ventricular Activation Research Articles

OBSERVATIONS ON THE RELATION BETWEEN VENTRICULAR ACTIVATION SEQUENCE AND THE HEMODYNAMIC STATE.

Hemodynamic parameters including records of left and right ventricular pressure, aortic pressure, the first derivative of the left ventricular pressure curve, and carotid flow were recorded with different patterns of ventricular activation. Special measures were used to achieve a comparable role of the atrium in ventricular filling with the different ventricular activation patterns. With an intact cardiac conduction system, definite but small differences in the hemodynamic parameters named were associated with different activation patterns. Normal ventricular activation produced slightly higher peak pressures in both ventricles and higher carotid flow than did abnormal activation. Each different activation pattern was associated with differences in the detailed shape of the ventricular pressure curves and with differences in the relative time of onset of pressure rise in right and left ventricles. When the specialized conduction system was blocked with large doses of ouabain, various patterns of ventricular activation were associated with marked differences of the hemodynamic parameters named. These findings may explain previously published conflicting results. They also suggest that disease of the conduction system may have a significant functional role in cardiac disease.

The Normal and Abnormal Unipolar Electrocardiogram in Infants and Children: An Analysis of the Normal QRS Complex Morphology and Ventricular Activation. Times

The Normal and Abnormal Unipolar Electrocardiogram in Infants and Children: An Analysis of the Normal QRS Complex Morphology and Ventricular Activation. Times

The Normal and Abnormal Unipolar Electrocardiogram in Infants and Children: An Analysis of the Normal QRS Complex Morphology and Ventricular Activation Times

ABSTRACT This monograph has two parts. In the first, Wasserburger presents a survey of electrocardiograms of normal infants and children based on 259,915 individual measurements of the QRS complexes of 1150 persons. The text is profusely illustrated with electrocardiograms demonstrating the variety of normal records seen in various age groups. In addition, there is a large number of charts of mean and maximum activation time and minimum and maximum amplitude of the Q, R, and S waves in leads AVR and precordial leads V3R through V6.In the second section the author uses the normal data to suggest criteria for distinguishing abnormal from normal electrocardiograms. A large number of electrocardiograms typical of each abnormality are shown, as well as tracings which present problems in interpretation. The author points out that measurements of a single deflection in a single lead often result in interpretation difficulties, and emphasizes the necessity

Cancellation of electrocardiographic effects during ventricular excitation.

Theoretical and experimental estimates of the amount of cancellation of electrocardiographic effects of ventricular excitation have been carried out. The theoretical estimate was based on the excitation sequence reported by Scher and consisted of comparing the total length of excitation fronts at several moments in the activation process with a measurement of the uncanceled portions of these fronts. Experimental estimates in 10 dogs were based on the relative areas of spatial magnitude curves during normal ventricular excitation and during stimulation of the ventricular site yielding the largest magnitude curve area. A theoretical estimate of the cancellation to be expected during ventricular stimulation was also carried out. The theoretical estimate of cancellation of electrocardiographic effects during normal ventricular activation was 71 per cent, while the experimental estimates varied from 51 per cent to 80 per cent, with an average of 66 per cent.

The significance of large lateral and small head-foot waves in the ballistocardiogram of ectopic beats

Comparison of three-plane ballistocardiograms during supraventricular and ectopic cycles in patients with atrial fibrillation showed that aberrant activation had minimal effect in altering the pattern of ectopic beats, while prematurity had marked and similar effects on ectopic beats and those with normal ventricular activation. Comparison of ectopic beats and normal beats in sinus rhythm showed that the absence of atrial contraction before ectopic beats contributed to the difference in pattern, but that premature contraction was far more important in determining the change in ballistocardiographic systolic complexes. Very early beats, which evoked faint first sounds and no second sounds, produced very little ballistocardiographic motion. Somewhat later beats, with normal or loud first sounds, occasionally had lateral systolic complexes larger than normal, although the head-foot complexes and carotid pulse waves were small. Factors which reduced the rate of return flow to the left ventricle (mitral stenosis; inspiratory phase of normal respiration) prolonged the interval after a normal systole during which premature beats evoked small ballistocardiographic waves, while aortic insufficiency and myocardial failure which hastened early inflow tended to produce short intervals in which small complexes were seen. These phenomena are interpreted as meaning that motion of blood, rather than motion of ventricular muscle masses, is responsible for almost all the ballistocardiographic force, and that motion of blood at the A-V orifices contributes greatly to the genesis of the lateral forces recorded during ventricular systole. It is noted that in 3 cases of sinus rhythm, ventricular ectopic beats with broad QRS complexes produced larger head-foot I-J waves and waves of more normal contour than those evoked by normally activated contractions. This may be due to interference of atrial and ventricular waves in normal beats, and absence of such interference in the ectopic beats.

Effect of Heart Rate on Cardiac Membrane Potentials and the Unipolar Electrogram

Effect of Heart Rate on Cardiac Membrane Potentials and the Unipolar Electrogram