Cardiac Autonomic Neuropathy

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Cardiac Autonomic Neuropathy
Dr. Ravishankar. S.B Dept. of Medicine J.S.S.
Hospital
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Autonomic Innervation of Cardia
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Definition
Presence of at least two abnormal out of
four performed autonomic functions

• Deep breathing
• Lying to Standing
• Valsalva Manoeure
• Orthostatic hypotension
• Drop in ppSBP

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How frequent is it ?
Prevalence
8 - 90 Different patient cohorts ( Type
1/2 Clinic / Population ) Different
assessment modalities Different minimal
Criteria used in definition Duration of
Diabetes
Type 2 ? 25 - 40
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How does it manifest?
Major Syndromes
Cardiac denervation Exercise intolerence Orthostat
ic hypotension

• Reduced heart rate variability (HRV) is the
  earliest
• indicator of CAN

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Why should we know about CAN?
Mortality 27 / 10 year

• Silent Cardiac Ischemia
• Arrhythmia's
• Sudden Cardiac Death
• Increased LV Hypertrophy
• Altered Coronary Vasomotor Dynamics
• Platelet Stickiness

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How can we diagnose or assess CAN?
Non-Invasive Bedside Tests
Blood Pressure response to standing ECG - QT
prolongation RR - Variation during deep
breathing Valsalva maneuver
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How can we diagnose or assess CAN?
Assessment of Sympatho-Vagal Activity
Power Spectral Analysis of HRV
Assessment of Myocardial Sympathetic innervation
MIBG Imaging
Association with Microalbuminuria
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Response to standing
Autonomic Reflex Arc

• Blood Pressure REST 1min 5min
• Fall in BP ?
  30/15
• Heart Rate Record ECG
• 30 s 15 s ( RR ) lt
  1.4

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RR - Variation during deep breathing
Parasympathetic Influence on heart

• Respiratory rate of 5/min
• Take continuous ECG for 1 min
• Maximum- Minimum heart rate ? 15 beats /min
• Ratio of longest RR interval ( Expiration )
  Shortest
• RR interval ( Inspiration ) EI 1.2

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Valsalva maneuver
Autonomic Reflex Arc

• Blow into the pipe of BP tubing to maintain 40
  mm of
• Hg for 15 sec.
• Phase I Rise in BP
• Phase II ? in BP Tachycardia.
• Phase III Fall in BP
• Phase IV Overshoot of BP Bradycardia.

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Valsalva maneuver
Valsalva Ratio Longest RR Shortest RR ?
1.4
ppSBP
Mean value of SBP during 2 hours after each
meal intake. 21 - 30 mm of Hg.
Corrected QT
Prolonged
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Variables Influencing CAN testing

• Time of the day
• Metabolic Status
• Distance from Insulin Meal
• Coffee Smoking Avoidance
• Presence of Cardiovascular disease drugs
• Posture - Standing sitting reduces HRV

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How does it matter to the patient? - Clinical
Implications

• Exercise prescription
• Tread mill testing
• Induction of Anaesthesia
• Avoid - Straining at Stool urine
• - Hot Showers
• - Hot weather

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Can we treat CAN or retard its progression ?

• Strict Glycemic Control
• Intensive therapy retards development of
  abnormal RR - variation and slows the
  deterioration of Autonomic dysfunction
• DCCT Trialists
• Reversible metabolic Component of CAN
• Buerger et al.
• Am J Cardiol 1999 Sep 15 84 (6)

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Alpha - lipoic acid
800 mg /day for 4 months
Reversion of baseline HRV as documented by
spectral analysis Root mean Square successive
difference in RR in Type 2 DM.
Diabets Care 1999, 20,3,369
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Quinapril
20 mg/day 3 Months

• Mainly normalizes parasympathetic variables .
• Effects are attributed to incresed vagal tone
  through
• baroreceptor activity
• Quinapril seems to combine ?-blokade and ACE
  inhibition.
• This effect is not seen with Lisinopril

Diabetes Care vol 20, 3, Mar 1997
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Message to take home

• CAN is common in Type 2 DM
• Diagnosis can be made at bedside with simple
  tests
• Advise the patients about the precautions to take
• Control DM intensely in those with CAN

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Message to take home

• Be on the alert for non specific symptoms
• Think of CAN when doing Tread Mill
• Think of CAN on Pre- Op/ Anaesthetic assessment
• Try medication ?