CARDIOVASCULAR AUTONOMIC NEUROPATHY IN DIABETICS

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CARDIOVASCULAR AUTONOMIC NEUROPATHY IN DIABETICS

• Michelle Anderton
• MVS 442
• February 4, 1999

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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

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ABOUT AUTONOMIC NEUROPATHY

• It is difficult to diagnose due to
• diffuse organ involvement
• gradual onset

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ABOUT AUTONOMIC NEUROPATHY

• AN can affect
• ocular pupil
• sweat glands
• GI tract
• bladder
• sex organs
• adrenal medullary system
• cardiovascular system

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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

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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

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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).

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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

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CAN EXERCISE ACTUALLY REDUCE CARDIOVASCULAR
AUTONOMIC NEUROPATHY IN DIABETICS??
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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

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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

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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

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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

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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

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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

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LIMITATIONS

• the fact that this was an isolated test doesnt
  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

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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