The present invention relates to an electronic system (1) for controlling the acquisition of an electrocardiogram. The system comprises a portable electronic device (2) and a mobile electronic device (3). the mobile electronic device comprises an optical device (3-1) for acquiring real time images of a part of a human body, comprises a screen (3-2) and comprises a processing unit (3-3) connected to the optical device and to the screen. the portable electronic device (2) comprises a first (2-1), a second (2-2) and a third (2-3) electrodes configured to generate a first (s1_r), a second (s2_r) and a third ( s3_r) detection electrical signals representing respectively the current generated in the skin by the activity of the heart of a human being at respective points where the first, second and third electrodes are positioned in said part of the human body. The mobile electronic device processing unit comprises an electrode placement guide module (3-3.1) for the first, second and third electrodes. the electrode placement guide module is configured to receive a plurality of real time images (i1, i2 ... in) representing the human body part, is configured to identify a feature of the human body part within at least a portion of said plurality of images is configured to calculate, depending on the identified characteristic, the positions at which to apply the first, second and third electrodes to the human body part and is configured to generate a direction signal (s_pl) which carries information indicating the calculated positions at which to apply the first, second and third electrodes. the screen is configured to receive said direction signal and is configured to display a real time image (i_ps_el) representing said human body part and further comprises a first positioning mark (a1), a second positioning mark (a2) ) and a third positioning mark (a3) representing the positions at which to apply the first, second and third electrodes, respectively.a presente invenção refe
