Author + information
- Received October 20, 1992
- Revision received April 19, 1993
- Accepted April 29, 1993
- Published online November 1, 1993.
- Kevin C. Allman, MB, BS,
- Martin J. Stevens, MB, ChB,
- Donald M. Wieland, PhD,
- Gary D. Hutchins, PhD,
- Edwin R. Wolfe Jr., MS,
- Douglas A. Greene, MD and
- Markus Schwaiger, MD, FACC∗
- ↵∗Address for correspondence: Dr. Markus Schwaiger, Nuklearmedizinische Klinik und Poliklinik der Technischen Universität München, Klinikum rechts der Isar, Ismaninger Strasse 22, D-81675 Munich, Germany.
Objectives. The purpose of this investigation was to evaluate the sympathetic nervous system of the heart by positron emission tomographic (PET) imaging in patients with diabetes mellitus with and without diabetic autonomic neuropathy.
Background. The clinical assessment of cardiac involvement in diabetic autonomic neuropathy has been limited to cardiovascular reflex testing. With the recent introduction of radiolabeled catecholamines such as carbon (C)-11 hydroxyephedrine, the sympathetic innervation of the heart can be specifically visualized with PET imaging.
Methods. Positron emission tomographic imaging was performed with C-11 hydroxyephedrine and rest myocardial blood flow imaging with nitrogen-13 ammonia. Three patient groups were studied, including healthy volunteers as control subjects, diabetic patients with normal autonomic function testing and diabetic patients with varying severity of autonomic neuropathy. Homogeneity of cardiac tracer retention as well as absolute tracer retention was determined by relating myocardial tracer retention to an arterial C-11 activity input function.
Results. Abnormal regional C-11 hydroxyephedrine retention was seen in seven of eight patients with autonomic neuropathy. Relative tracer retention was significantly reduced in apical, inferior and lateral segments. The extent of the abnormality correlated with the severity of conventional markers of autonomic dysfunction. Absolute myocardial tracer retention index measurements showed a 45 ± 21% decrease in distal compared with proximal myocardial segments in autonomic neuropathy (0.069 ± 0.037 min−1vs. 0.13 ± 0.052 min−1, p = 0.02).
Conclusions. This study demonstrates a heterogeneous pattern of neuronal abnormalities in patients with diabetic cardiac neuropathy. The extent of this abnormality correlated with the severity of neuropathy assessed by conventional tests. Future studies in larger groups of patients are required to define the relative sensitivity of this imaging approach in detecting cardiac neuropathy and to determine the clinical significance of these scintigraphic findings in comparison with conventional markers of autonomic innervation.
☆ This work was performed during the tenure of Dr. Schwaiger as an established investigatorship of the American Heart Association, Dallas, Texas. It was supported by Grants R01 HL 4107, R01 HL 47543/R01 HL 27553 from the National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland; Grants R01 DK 38304, 5 P60 DK20572,5 U01 DK30636 from the National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health and Grant DE FG02-90ER61091 from the Department of Energy, Washington, DC.
- Received October 20, 1992.
- Revision received April 19, 1993.
- Accepted April 29, 1993.