. Medical diagnosis for the student and practitioner. plete compensatory pause. 3. Nodal extrasystoles are premature heart cycles in which the impulsefor contraction is supposed to arise in the auriculo-ventricular node insteadof in the pacemaker, (sino-auricular node). These are indicated on therecord by an abnormally early heart cycle normal in appearance with theexception that the P-wave is absent or merely suggested. The compen-satory pause following is equivalent to two heart cycles. A short run of nodal extrasystoles is spoken of as nodal rhythm. Fibrillation is characterized in the elec
. Medical diagnosis for the student and practitioner. plete compensatory pause. 3. Nodal extrasystoles are premature heart cycles in which the impulsefor contraction is supposed to arise in the auriculo-ventricular node insteadof in the pacemaker, (sino-auricular node). These are indicated on therecord by an abnormally early heart cycle normal in appearance with theexception that the P-wave is absent or merely suggested. The compen-satory pause following is equivalent to two heart cycles. A short run of nodal extrasystoles is spoken of as nodal rhythm. Fibrillation is characterized in the electrocardiographic record by theabsence of P-waves, the occurrence of multiple coarse or fine undulations(fibrillatory waves), and an utterly disorderly rhythm in the occurrence ofthe R-waves. The latter show also considerable variation in height. Fine fibrillation is usually associated with the rapid rates while withcoarse fibrillation we have usually a slower rate. The P-wave being absent,of course there is no P-R interval. 34 53° MEDICAL DIAGNOSIS. Y ?UZJHLliL -IPillllll^ 1 1 i ! A - ! is ! 1 7T (IMZtZ MkJM E*Sj3. f « r T^--*- -•-— -At ? irr 7/262/2 Fig. 228.—Mr. I. H. Electrocardiograph record showing a right ventricular extra-systole in each Lead. The direction of the deflections of ventricular extrasystoles in LeadI is opposite to that of the deflections in the other two leads. ELECTROCARDIOGRAPHIC RECORDS 531 Block.—Heart block may be either complete or partial. In completeblock there is an entire dissociation between the P-waves and the R (or S)waves, together with a slow ventricular rate, as indicated by the number ofR-waves occurring in the 6-second interval. In this condition the complete block existing in the conducting fibrescompels the ventricles to adopt their own, inherent, slow deliberate rhythmcausing an occurrence of correspondingly few R (or S) waves. The con-
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectdiagnos, bookyear1922
