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Cardio Diabetes Medicine 2017 105

Diabetic Cardiovascular

Autonomic Neuropathy

Dr. Ulhas M. Pandurangi, MD., DM (Cardio).,

Chief. Cardiac Electrophysiology & Pacing
The Madras Medical Mission

Introduction with PNP have asymptomatic CAN, whereas 100%
Diabetic cardiovascular autonomic neuropathy of those with symptomatic DCAN present classical
1,2
(DCAN) is a neuro-humoral regulation disturbance PNP .
due to malfunction of autonomic nervous system
(ANS).DCAN represents a significant cause of mor- Pathogenesis
bidity and mortality in patients with diabetes melli- DCAN is widely believed and largely proven to be to
tus (DM)and is associated with a high risk of car- be the result of complex interactions among degree
diac arrhythmias and sudden death.It is one of the of glycemic control, disease duration, age-related
most insidious complications of DM especially if it is neuronal attrition, and systolic and diastolic blood
long standing and poorly controlled. DCAN is often pressure . Hyperglycemia plays the key role in the
1,7
overlooked both in terms of diagnosis and treatment activation of various biochemical pathways related to
simply because there is no widely accepted single the metabolic and/or redox state of the cell, which,
approach to its diagnosis and management 1,2,3 .This in concert with impaired nerve perfusion, contribute
review covers the epidemiology, pathophysiology, to the development and progression of diabetic neu-
clinical presentation, and diagnosis of DCAN and ropathies.
discusses current evidence on approaches to pre-
vention and treatment. Pathophysiology:
It has been shown that chronic hyperglycemia pro-
Epidemiology: motes progressive autonomic neural dysfunction
Diabetic neuropathies, including DCAN, are a com- (Fig.1) in a manner that parallels the development of
mon chronic complication of type 1 and type 2 DM peripheral neuropathy, e.g., beginning distally and
and confer high morbidity and mortality. The reported progressing proximally. The vagus nerve, the lon-
prevalence varies greatly depending on the criteria gest autonomic nerve, mediates 75% of all parasym-
used to identify DCAN and the population studied. pathetic activity (Fig.2). Because neuropathy is seen
DCAN prevalence ranges from as low as 2.5% of the first in the longest fibers, the earliest manifestations
primary prevention cohort in the Diabetes Control of autonomic neuropathy in diabetes tend to be as-
4
and Complications Trial (DCCT) to as high as 90% of sociated with parasympathetic denervation. As such,
patients with long-standing type 1 diabetes who were the initial development of DCAN is characterized by
potential candidates for a pancreas transplantation . early augmentation of sympathetic tone .The initial
5
2,7
In a large cohort of patients with type 1 and type 2 augmentation in cardiac sympathetic activity with
diabetes, Ziegler et al. using predefined heart rate subsequent abnormal norepinephrine signalling and
2,6,
variability (HRV) tests and spectral analysis of the metabolism, increased mitochondrial oxidative stress,
R-R intervals, found that 25.3% of patients with type and calcium- dependent apoptosis may contribute to
1 diabetes and 34.3% of patients with type 2 diabetes myocardial injury and may explain the high risk of
had abnormal findings. Age, sex, and other risk fac- cardiac events and sudden death in these patients.
tors may also influence DCAN development. DCAN The sympathetic imbalance associated with DCAN
is more often seen in patients with polyneuropathy may critically influence myocardial substrate utili-
(PNP). Approximately 50% of the diabetic patients

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