Bedside Recognition of the Disturbances of Cardiac Rhythm
Present day knowledge of the disturbances of heart rhythm is based primarily upon earlier studies of the arrhythmias by means of the polygraph and the electrocardiograph. Correlation of the results of these studies with careful clinical observations has now made it possible to differentiate most of the arrhythmias at the bedside without instrumental aid. The electrocardiograph is, of course, an instrument of great value but its field of greatest usefulness no longer has to do with the disturbances of cardiac rhythm. Electrocardiograms should be made in every case of actual or suspected organic heart disease but, for the experienced observer, the recording of abnormal heart rhythms in this manner usually will serve only to corroborate an earlier clinical diagnosis. Even in these cases, however, the tracings may give additional information of importance, and for the detection of certain disturbances of rhythm, graphic registration remains indispensable.
In any discussion of the irregularities of heart rhythm, mention should be made of sinus arrhythmia. In this condition there is a gradual increase in the heart rate during inspiration and a corresponding decrease during expiration. The disturbance is encountered commonly in children and is a usual finding in individuals who have neurocirculatory asthenia. It may also develop as a manifestation of digitalis overdosage, and this is the only situation in which it becomes of clinical importance. Sinus arrhythmia often can be accentuated by slow, deep breathing and abolished by exercise.
Except for sinus arrhythmia, the most common disturbance of cardiac. . .