"The classification of dysautonomias has been confusing, and the pathophysiology obscure. We examined sympathetic innervation of the heart in patients with acquired, idiopathic dysautonomias using thoracic positron-emission tomography and assessments of the entry rate of the sympathetic neurotransmitter norepinephrine into the cardiac venous drainage (cardiac norepinephrine spillover). We related the laboratory findings to signs of sympathetic neurocirculatory failure (orthostatic hypotension and abnormal blood-pressure responses associated with the Valsalva maneuver), central neural degeneration, and responsiveness to treatment with levodopa–carbidopa (Sinemet)."
"The results of 6-[18F]fluorodopamine positron-emission tomography and neurochemical analyses support a new clinical pathophysiologic classification of dysautonomias, based on the occurrence of sympathetic neurocirculatory failure, signs of central neurodegeneration, and responsiveness to levodopa–carbidopa."
Sympathetic Cardioneuropathy in Dysautonomias
David S. Goldstein, M.D., Ph.D., Courtney Holmes, C.M.T., Richard O. Cannon, M.D., Graeme Eisenhofer, Ph.D., and Irwin J. Kopin, M.D.
The New England Journal of Medicine , March 6, 1997