Clinical electrocardiography . a high peripheral resistance, are incapable ofopening the aortic cusps, since intracardiac pressure fails to equalthe pressure in the aorta, and they are thus not transmitted to theperipheral arteries. Such contractions are termed abortiveor frustrane. Auricular Premature Contractions.—Premature contractionarising near the sino-auricular node gives an electrocardiogramwhich differs from the normal only in the resulting P wave occurs prematurely, but is followed by a Q R S groupand a T wave of normal characteristics. The impulse responsible CARDIAC A
Clinical electrocardiography . a high peripheral resistance, are incapable ofopening the aortic cusps, since intracardiac pressure fails to equalthe pressure in the aorta, and they are thus not transmitted to theperipheral arteries. Such contractions are termed abortiveor frustrane. Auricular Premature Contractions.—Premature contractionarising near the sino-auricular node gives an electrocardiogramwhich differs from the normal only in the resulting P wave occurs prematurely, but is followed by a Q R S groupand a T wave of normal characteristics. The impulse responsible CARDIAC ARHYTHMIAS 59 for this ectopic beat is in the immediate vicinity of the normalpace-maker, and, being supraventricular, permits the resultingexcitation to traverse normal paths to provoke ventricular response. * !s Fig. 23.—Schematic graph of auricular premature contractions. Figure 23 illustrates the mechanism of auricular premature con-tractions. Figure 24 is an electrocardiogram of such an auricularpremature Fig. 24.—Auricular premature contraction (Exsys.) arising in the immediatevicinity of the sino-auricular node. The P wave is upright. Electrocardiogramin Derivation II. When the ectopic impulse arises at a point in the auricularmusculature distant from the sino-auricular node the P wave
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Keywords: ., bookcentury1900, bookdecade1920, bookidclinicalelec, bookyear1922
