Abnormalities of Atrioventricular Conduction
The rate and rhythm of atria and ventricles can be noted objectively, but the origin of the impulses responsible for these features must be deduced from the characteristics of the curves they produce, and whether activity in the ventricles represents progression of an impulse from the atria, or vice versa, or they are unrelated, is always a judgment; the upper and lower hearts can interact in a variety of ways, and are capable of functioning independently. If there are both Ps and QRSs, a PR interval, defined simply as the distance between the beginning of P and the beginning of the next QRS, can be measured even when there is complete AV block. To record a figure for a PR interval is to express the opinion that the impulse responsible for atrial activity continued through the AV junction and depolarized the ventricles; all the tracing shows is Ps and QRSs.
KeywordsAccessory Pathway Atrial Activity Right Bundle Branch Block Ventricular Activity Versus Block
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