Before moving on to atrium and ventricular dissection, it is worth remembering some technical aspects. You should always check that paper speed and calibration are standard and thus respectively 25 mm/s and 10 mm = 1 mV. An increase in speed or amplitude may be required when greater precision in estimation of intervals or small amplitude waves is important. True dextrocardia must be distinguished from misplacement of the limb leads (the so-called nurse’s dextrocardia).

When faced with an improbable ECG, you have to question the correctness of lead placement, sometimes poorly positioned due to staff carelessness, thoracic deformity, dressings, etc. [1, 2] The surface ECG is a simple technique, but that does not mean it can be performed superficially. Just like cooking, it is the simplest recipes that require perfection of the few necessary ingredients. Every laboratory should comply with the standard placement of the electrodes, and nurses should be skilled in being able to put children of all ages at their ease, resorting to various arts ranging from soap bubbles to smartphones.

In remote-viewed tracings, whether sent by fax or other means, you have to make sure that the relationship with the original is 1:1; even small differences of scale can lead to blunders, for example in the calculation of the QT interval (if you don’t know the scale, you can count the little boxes that at standard paper speed correspond to 40 ms). Sometimes there are funny artifacts: the oscillatory ventilation often used in neonatal intensive care can simulate drug-resistant flutter (diagnosis and therapy are electric, just switch off the oscillator) [3]. Even hiccups can create bizarre waves resembling extrasystoles which are neither supraventricular nor ventricular, but simply underventricular or diaphragmatic. Congenital heart disease may require nonstandard leads such as V3R, V4R, and V7: the first two increase the sensitivity of the right overload [4], while V4R (positioned on the right midclavicular fifth intercostal space) can be an excellent alternative to V1–V2 which cannot be applied due to dressings or for other reasons. With ECGs that are “RBBB like” or with an “atypical” RBBB, in family members of patients with Brugada syndrome , or in the case of unexplained syncope, in addition to the ECG standard you should do an ECG with right precordial leads (V1 and V2) moved high in the third and in the second intercostal space. In the same conditions, it is also useful to perform an ECG in the course of fever as it is known that hyperthermia can unmask the Brugada pattern. Modern electrocardiographs have sample rate and bandwidth higher, respectively, than 500 samples/s and 250 Hz – they write very well but they don’t read quite so well. Automatic diagnosis may be incomplete, petulant, or catastrophic and is not always reliable, especially when the machines do not know they are dealing with a child and see infarction instead of infants [5]. “Manual” diagnosis should avoid as much as possible scary terms like “block,” “delayed,” “nonspecific alteration,” and “anomaly” which are not much help. When these terms are unavoidable, they should be followed by conclusions that are as reassuring as possible. You should also avoid defensive adverbs and phrases such as likely and cannot be excluded followed by a dozen differential diagnoses. The perfect report consists of a single word: “N o r m a l.” A broken clock tells the correct time at least twice a day. Cardiologists who are too far forward or too far back never get it right. For all the time and amplitude parameters, refer to the normal value tables; the Davignon and Rijnbeek tables are still useful [6, 7] (Table 2.1).