Kontaxis, Spyridon Lázaro Plaza, Jesús Corino, Valentina Sandberg, Frida Bailón Luesma, Raquel Laguna Lasaosa, Pablo Sörnmo, Leif ECG-derived respiratory rate in atrial fibrillation IEEE trans. biomed. eng. 10.1109/TBME.2019.2923587 2019 2019