The practical value of electrocardiography.

Electrocardiography, a graphic method of investigation of the heart, had such a rapid development that periodic evaluations of its practical usefulness are necessary. Overemphasis by enthusiastic workers may stress the value of this method beyond its actual possibilities; this may cause deceptions or diagnostic errors, or simply prevent the use of other, more appropriate, methods of investigation. On the other hand, underemphasis by a few die-hard old timers, misuse by poorly trained workers, or disappointment in its findings, occasionally cause unwarranted criticisms. It is appropriate to say that, in the presence of wide enthusiasm, criticisms are usually limited to personal comments and seldom find their way into medical literature. Electrocardiographic technique is now established on a generally standardized basis. This consists of the use of 12 leads (three standard limb leads, three augmented V-leads of the limbs, and six precordial V-leads). Additional chest, esophageal, or epigastric leads, as well as functional tests, are sometimes necessary. An electrocardiographic report can be of different types: (1) purely descriptive; (2) including analysis of certain peculiarities like axis deviation, premature beats, etc.; (3) including a diagnosis such as “atrial flutter,” and “myocardial infarction” or “digitalis heart”. Complete electrocardiographic evaluation can be done only by a cardiologist who has examined the patient. The study of multiple precordial leads emphasizes the need of close supervision of the technician. It is impossible to draw a sharp line between normal and abnormal tracings. In reaching a decision, the observer must consider the possible occurrence of a certain variation in the ecg of a normal person. Personal experience and additional clinical and laboratory data determine whether an abnormality should be considered pathologic. The electrocardiogram can be used for “timing” certain accidents or waves recorded by means of mechanical, sound, or roentgenological methods. Thus, a venous tracing, a phonocardiogram, or an electrokymogram, can be recorded together with an electrocardiogram. An electrocardiogram gives accurate information about the pacemaker of the heart and permits evaluation of the atnial and ventricular rates. Thus, the ectopic rhythms are easily studied. Rhythms by usurpation are those where an ectopic focus with high excitability becomes the pacemaker (atrial and nodal tachycardia, atrial flutter, ventricular tachycardia, atrial fibrillation, premature contractions, and also ventricular flutter and fibrillation). Rhythms by default are those where lack of a normal sinus Impulse or interruption in its transmission