Download CARDIOVASCULAR AUTONOMIC NEUROPATHY IN DIABETICS

CARDIOVASCULAR
AUTONOMIC NEUROPATHY IN
DIABETICS
Michelle Anderton
MVS 442
February 4, 1999
BASIC DEFINITIONS
Autonomic Nervous System: Part of the nervous system that
is responsible for control and regulation of the involuntary
bodily functions, including those of the heart, blood
vessels, visceral smooth muscles and glands. It consists of
the sympathetic system, which in general stimulates the
body to prepare for physical action and emergency, and the
parasympathetic system which stimulates the opposite
responses.
Neuropathy: Any disease of the nervous system
ABOUT AUTONOMIC
NEUROPATHY
• It is difficult to diagnose due to:
– diffuse organ involvement
– gradual onset
ABOUT AUTONOMIC
NEUROPATHY
• AN can affect:
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ocular pupil
sweat glands
GI tract
bladder
sex organs
adrenal medullary system
cardiovascular system
ABOUT AUTONOMIC
NEUROPATHY
• It is a common complication of both types
of diabetes mellitus (type I and II)
• One of the earliest detectable complications
of long-term glucotoxicity
ABOUT AUTONOMIC
NEUROPATHY (POSSIBLE
CAUSES)
• Excess of sorbitol (a crystalline alcohol) in
the nerve tissue
– interferes with normal nerve function via an
osmotic effect that results in nerve swelling
– also leads to decreases in nerve myoinositol
which is important for normal operation of the
Na+ - K+ - AT-Pase pump
• important in maintaining proper membrane potential
• a decrease in pump activity = decrease in nerve
conduction velocity
WHAT IS CARDIOVASCULAR
AUTONOMIC NEUROPATHY??
• It is basically cardiac denervation which can
result in:
– a fixed HR that is unresponsive to exercise or
stress, which in turn can lead to:
• cardiac arrhythmias and sudden death
– there is an increased risk when under anesthesia
and for the occurrence of silent myocardial
infarction and myocardial ischemia (lack of
blood supply to the heart muscle).
WHAT IS CARDIOVASCULAR
AUTONOMIC NEUROPATHY??
• Difficult to detect:
– need to rule out various other disorders that
have similar symptoms to CAN such as:
• vestibular problems, hypoglycemia, dehydration.
adrenal insufficiency, anemia and hypothyroidism
CAN EXERCISE ACTUALLY
REDUCE
CARDIOVASCULAR
AUTONOMIC NEUROPATHY
IN DIABETICS??
PURPOSE AND SUBJECTS
• Purpose of study:
– compare cardiovascular response to exercise in
patients with non-insulin-dependent diabetes
mellitus (NIDDM) with a group of healthy
subjects
• 108 NIDDM subjects
• 112 healthy subjects
PROCEDURE
– each group was matched to one another
according to age, sex, physical fitness and
presence of hypertension
– groups were given clinical exams to determine
weight, height, BMI and BP
– all patients performed two cardiovascular tests:
deep breathing and lying to standing.
– tests were scored on a basis of a set normality
• normal = 0 , abnormal = 2
PROCEDURE
• then an overall cardiac autonomic nervous
function (CAN) score was given
• then a cycle ergometer test was
administered until either max. HR or
exhaustion occurred
FINDINGS
• during exercise, SBP and DBP changes
were much lower in the diabetic patients
• during recovery HR decrease was also
significantly slower
– even diabetic subjects without outward signs of
CAN experienced the above results
• no differences in total work capacity and
peak HR were found
CONCLUSIONS
• there is an abnormal CV response during
exercise in NIDDM patients, which could
be due to:
– “depressed contractility or reduction in preload,
possibly due to decreased ventricular
compliance”
CONCLUSIONS
– “autonomic dysfunction may directly affect left
ventricular function...abnormal coordination of
the peripheral vasculature could impair
ventricular preload and afterload, thus changing
ventricular volume and reducing pressure and
ejection fraction response during exercise”
LIMITATIONS
• the fact that this was an isolated test doesn’t
quite tell us how the heart would react to a
prolonged exercise program.
– it is possible that with the proper routine, the
heart could be trained to function at a higher
level
PREVENTION
• maintenance of a normal or near-normal
blood glucose level could help prevent, or at
least slow the accumulation of sorbitol,
which could reduce the affects of CAN