Detection of autonomic nervous dysfunction by SL manoeuvre

Area of Science:

• Cardiology
• Neurology
• Diabetology

Background:

• Diabetic autonomic neuropathy is a common complication affecting cardiovascular function.
• Autonomic dysfunction can lead to significant morbidity and mortality in diabetic individuals.

Purpose of the Study:

• To evaluate the immediate heart rate response to standing and lying in diabetic subjects.
• To assess the utility of specific cardiovascular autonomic tests in diagnosing autonomic neuropathy in diabetes.

Main Methods:

• 100 diabetic subjects and 50 controls underwent cardiovascular autonomic tests, including heart rate response to postural changes (standing and lying).
• Patients were categorized into groups based on the presence and severity of autonomic neuropathy using a scoring system.
• Two specific tests, SL1 (ratio of R-R intervals) and SL2 (another R-R interval ratio), were analyzed to assess parasympathetic and sympathetic function.

Main Results:

• Diabetic subjects, particularly those with autonomic neuropathy, showed significantly reduced SL1 and SL2 values compared to controls.
• Subjects without autonomic neuropathy also exhibited altered SL1 and SL2 compared to controls, indicating early autonomic dysfunction.
• Proposed diagnostic limits for SL1 (1.12 lowest normal, 1.08 highest abnormal) and SL2 (1.23 normal, 1.18 highest abnormal) were suggested.

Conclusions:

• The SL1 test appears to be a sensitive indicator of parasympathetic dysfunction.
• The SL2 test reflects mixed sympathetic and parasympathetic activity, predominantly sympathetic, useful in diagnosing autonomic neuropathy.
• These heart rate variability tests can aid in the early diagnosis and management of cardiovascular autonomic neuropathy in diabetic patients.