Francisco (Paco) Torrent-Guasp, a Spanish cardiologist working in De'nia, Alicante, discovered that the complex structure of the ventricular myocardium is due to a double-loop helical orientation of a single muscular band that extends from the pulmonary artery to the aorta, with a 180-degree twist in its middle part. He predicted the twist-untwist motion of the ventricles and suggested that this is due to agonist-antagonist mechanics of the ventricular band segments.