Walter Gaskell and the understanding of atrioventricular conduction and block.

Walter Holbrook Gaskell was a nineteenth-century British physiologist whose investigations from 1874 until 1889 became central to our current understanding of cardiac physiology. His many cardiac contributions include the following: 1) the recognition of certain inherent properties of cardiac muscle; 2) the experimental proof that led to the acceptance of the myogenic theory of the origin of the heartbeat; 3) the mapping of the anatomy of the sympathetic nervous system; 4) the understanding of the dual autonomic control of the heart; 5) the discovery of the vasodilating effect of sympathetic stimulation on blood flow through skeletal muscle arteries; and 6) the introduction of the concept of heart block. Gaskell's elucidation of the sequence of cardiac contraction and atrioventricular block and his concepts of rhythmicity, excitability, contractility, conductivity and tonicity provided the physiologic explanation necessary for the future understanding of cardiac rhythm disturbances.