Sympathetic Innervation and Blood Flow in the Diabetec Heart

Abstract

The balance of the activity of the cardiac sympathetic and parasympathetic nervous system plays a key role for the functional and structural performance of the diabetic heart.¹ Metabolic, vascular/hemorrheological and, in type 1 diabetes mellitus, immunological factors are currently hypothezised to contribute to the pathogenesis, which, however, has not been fully elucidated.¹ The heterogeneous pattern and the high extent of dysfunction of the cardiac sympathetic nervous system in diabetes mellitus had remained largely unknown until advanced scintigraphic techniques for direct characterization of dysfunction of sympathetic neurons in the living heart emerged in the 1990’s. Previously, diagnosis of cardiac sympathetic abnormalities had been mainly based on conventional non-invasive cardiac reflex tests, including measurements of heart rate variation and blood pressure changes to standing. These tests, however, only indirectly assess diabetic cardiac autonomic dysfunction, they do not differentiate absolutely between sympathetic and parasympathetic function and they do not assess the heart regionally. Imbalance of the activity of the cardiac sympathetic nervous system is suggested to lead to multiple functional disturbances and to increase the risk for arrythmogenicity of the diabetic heart.²