Cardiac sympathetic innervation and blood flow regulation of the diabetic heart

A key problem in ischemia-induced impairment of the vascular performance of the diabetic heart is the often-unrecognized cardiac sympathetic dysfuncti on. Advanced single-photon emission computed tomography (SPECT) and positro n emission tomography (PET) using the radiopharmaceuticals, I-123-metaiodob enzylguanidine (I-123-MIBG) and C-11-hydroxyephedrine (C-11-HED), have show n that dysfunction of cardiac sympathetic nerves is present to a large exte nt in both type I and type 2 diabetes. The pattern of sympathetic disturban ces is heterogeneous with a predominant effect in the posterior myocardial region. Furthermore, myocardial blood flow assessment with PET has shown th at endothelial-dependent vasodilatation is reduced in proportion to the mag nitude of cardiac sympathetic dysfunction. These mechanisms are currently p roposed to lead from early changes to advanced impairment of cardiac functi on in diabetes. Copyright (C) 2001 John Wiley & Sons, Ltd.