The sympathetic regulation of the heart.

Abstract

Dr Murray Esler discusses the role of the sympathetic innervation to the heart with relevance to Takotsubo cardiomyopathy The spinal cells of origin for the sympathetic nerves of the heart lie in the intermediolateral cell column of the upper 3–4 thoracic segments of the spinal cord. These cardiac pre-ganglionic neurons relay primarily through the stellate (cervicothoracic) and thoracic sympathetic ganglia. The output of post-ganglionic fibres from these ganglia are grouped in the superior, middle and inferior cardiac nerves, to be distributed to the cardiac plexus of nerves on the surface of the heart, then to the individual anatomical components receiving sympathetic innervation. Intrinsic cardiac ganglia are enmeshed in the cardiac neural plexus, and participate in autonomic regulatory influences on the heart. Central reflex and behavioural sympathetic control of the heart resides in four hierarchical levels of the neuroaxis: cortex (insular cortex, anterior cingulate cortex); subcortical forebrain (hypothalamus, amygdala); brainstem (including rostral ventrolateral medulla, caudal ventrolateral medulla, nucleus tractus solitarius, periaqueductal gray, raphe nuclei); spinal level (pre-ganglionic sympathetic neurons of intermediolateral column). From some of these brain regions there are direct, monosynaptic relays to the spinal pre-ganglionic neurons. With behavioural stimuli, CNS inputs to sympathetic outflow from the insular cortex, hypothalamus, and amygdala are prominent. In many and diverse circumstances …