[P]acemakers elevate the heart rate... but they don’t always reproduce a normal heartbeat. ...[I]f the pacemaker leads are placed directly in ventric… - Gerald Buckberg

Stopping the heart is accomplished by shutting off its blood supply (a process called ). I discovered blood ... We initally realized the return of regular blood to a heart that has been without blood supply, will create severe damage. We then discovered how to prevent this injury by using a blood cardioplegic solution that contains selected chemical ingredients (including key amino acids...)that safely protects the heart... [E]ffectiveness... depended upon their arriving at specific locations... But many of our patients had narrowed arteries... This barrier was overcome by delivering it in a "backward direction" via the heart’s main vein... further enhanced by administering it at different temperatures during the beginning and end of the operation.

Dr Torrent-Guasp... formalized this description by indicating that the heart looked like a "rope"... [in] three parts: a beginning and an end at the and ; a wraparound loop called a basal loop; and... a helix that he called the apical loop. ...He described a [billion year old] worm... with a vascular tube... like a rope, with a venous and an arterial system. ...[F]ish evolved to show the first generation of a heart, containing a single pumping chamber, and included gills... [Next] the amphibian and the reptile appeared, in which we observe an atrium and a ventricle. Each chamber was separated by an atrial and ventricular septal defect. Human beings developed... [later] and both the atrial defect and the ventricular defect are closed.

[I]t was thought many years ago that no one could understand the heart. The heart was called the .