Physiology of the Helical Heart

The aim of this study was to investigate: a) beginning and ends of the myocardium; b) the slippage between the myocardial segments implies that there should be an antifriction mechanism; c) the electrical activation of the endocardial and epicardial segments; d) the mechanism of active suction during the diastolic isovolumic phase. Ten young-bovine hearts and eight human hearts were used for anatomical- histological analysis and five patients with normal QRS complexes underwent threedimensional endoepicardial electroanatomic mapping. A nucleus (cardiac fulcrum) underlying the right trigone was found in all the hearts. Hyaluronic acid was found in the cleavage planes between the myocardial bundles. Endo-epicardial mapping demonstrated an electrical activation sequence consistent with the mechanism of ventricular twist. The finding of the fulcrum provides support to the spiral myocardial muscle. The hyaluronic acid would act as a lubricant. Electrophysiological studies explain the ventricular twist and the active suction mechanism.