History

Scientific interest in the heart goes back centuries. Some of the most basic understandings about the operation and specifically the electrical currents of the heart were discussed during the May 17, 1888 Proceedings of the Royal Society of London by Professor J.A. McWilliam of the University of Aberdeen. The following conclusions were based on his studies of mammalian hearts in cats, dogs, rabbits, rats, hedgehogs, and guinea-pigs.

• An all or nothing approach to heart contraction
  • If a stimulus was strong enough to excite contraction, it produced a maximal contraction
• The application of interrupted currents induces fibrillar contractions which can be recovered from even after long period under the combined influence of artificial respiration, rhythmical compression of the ventricles, and administration of pilocarpin (all methods used for heart attack patients today)
  • Further, when the cardiac muscle has been depressed by the methods above, the application of interrupted currents does not induce fibrillar contraction, but can accelerate the rhythm already present in the heart.
• Some spontaneous rhythmic currents are myogenic (discussed further in Physiology)
• Heating of the “ostial part of a great vein”, for example termination of the vena cava superior causes acceleration in the rhythm of the whole heart
  • Additionally, heating of the “ventricular wall of a great vein” causes very little or no change in the pace of the contractions
• The propagation of the contraction within the walls of the auricles and ventricles is not dependent on the action of the nerves lying near the surface of those parts

  • The contraction continued to be propagated even when the surface of the heart was washed with strong ammonia

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