There are many electrocardiographic changes in sinoatrial block. Only 2nd and 3rd degree blocks can be analysed on surface recordings. However, they manifest themselves by pauses, the descriptions of which are rich and varied. They also vary according to the circumstances of apparition and the escape rhythms which accompany them. Related ECG changes such as chronotropic insufficiency or carotid sinus syndrome have been described. However, their significance is not univocal and only a precise analysis of the ECG recordings allows correct interpretation of the clinical and paraclinical signs and the institution of appropriate therapy.