In the following pages an attempt is made
to discuss certain aspects of complete heart-block
as it occurs in man. While the nervous control of
the auricles is well understood, much remains to be
discovered regarding the influence of the extrinsic
nerve supply to the ventricles. Tn. approaching this
problem, the heart, in which the auricles and ventricles are dissociated in their rhythms lends an
admirable opportunity for the investigation of its
nervous regulation. By the use of certain drugs
and other procedures in a series of fourteen cases
of complete heart-block, the facts accumulated suggests that the ventricles, despite the presence of
complete block, are directly under the control of
the parasympathetic and sympathetic systems. The
evidence leading to this conclusion is summarised at
the conclusion of each section of this report.Electrocardiograms have revealed four distinct disorders of cardiac mechanism over the various phases of the Stokes-Adams syndrome. Two examples of ventricular arrest occurring during partial
heart-block are recorded, and two during complete
heart-block. In one of these paroxysmal ventricular tachycardia followed by ventricular fibrillation
preceded the onset of asystole. This attack was
treated by the intra-cardiac injection of 0.5 c.c. adrenalin. The patient recovered
