منابع مشابه
[The P wave, P-R interval, and Q-T ratio of the normal orthogonal electrocardiogram].
E LECTRIC signals generated from the heart are more properly defined in mag. n-itude and direction by an orthogomial 3 lead system with constancy iii lead direction and strenogth.l1The spatial heart veetors are projected on the 3 perpendicular axes of such a Cartesiani coordiiiate system, and are readily available for analysis. With the advent of corrected orthogonal lead systems1-4 it appeared...
متن کاملThe P wave and P-R interval. Effects of the site of origin of atrial depolarization.
The atria of 37 patients were paced from selected sites during cardiac surgery. When the atria were paced from endocardial sites low in the right atrium, the P waves in ECG leads II, III, and aVF were shown to be either negative, biphasic, or positive, depending on the site paced. When the endocardial sites were paced, the P-R intervals were, almost without exception, less than 0.12 sec. When t...
متن کاملElectrical activity during the P-R interval.
RECENT studies of the electrical activity of single cardiac fibers suggest that most, if not all, disturbances of rhythm have their origin in specialized cardiac tissues rather than in the muscle fibers of the atria or ventricles.' Similarly, many disorders of conduction result from disordered function of these same structures. Unfortunately, the leads employed in clinical electrocardiography f...
متن کاملVariability of R-R, P wave-to-R wave, and R wave-to-T wave intervals.
We analyzed the effect of changing posture from supine to standing on the variability of R-R, P-R, and R-T intervals in 10 healthy volunteers using power spectral analysis. An electrocardiogram and respiratory trace were recorded before and after posture change. Variability in the P-R and R-T intervals was much less than in the R-R interval and demonstrated a lower low-frequency (LF)-to-high-fr...
متن کاملThe normal P-R interval in infants and children.
The value of the P-R interval in the study and evaluation of treatment of rheumatic carditis, a disease predominantly of the younger ages, has prompted a re-examination of the normal P-R standards for infants and children. This study reports these data as obtained from 506 normal infants and children. The data reveal that both age and heart rate exert a significant influence on the P-R interval...
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ژورنال
عنوان ژورنال: Circulation
سال: 1970
ISSN: 0009-7322,1524-4539
DOI: 10.1161/01.cir.42.4.653