AN APPROACH TO THE DETECTION OF AUTONOMIC NEUROPATHY BY USE OF SIGNAL-AVERAGED ELECTROCARDIOGRAPHY

The beat-to-beat variation of PR interval, which is thought to be a re flection of autonomic nervous system, is difficult to measure with acc uracy because the variation is too subtle. However, R wave amplitude i n the P wave triggered SAECG is easily attenuated in comparison to tha t in the R wave triggered SAECG, which might be due to PR interval flu ctuation. To determine whether autonomic neuropathy could be detected by use of SAECG, two types of SAECGs triggered by P and R waves were r ecorded in 23 diabetics with autonomic neuropathy and 41 age matched c ontrols. The peak voltage of filtered QRS complex was measured in the R wave and P wave triggered SAECGs. Percent attenuation of the filtere d QRS voltage was calculated by dividing the difference between the vo ltages in the R wave and P wave triggered SAECGs by the voltage in R w ave triggered SAECG. The percent attenuation of filtered QRS voltage w as significantly smaller in diabetics with autonomic neuropathy than c ontrols (4.6% +/- 4.9% vs 16.3% +/- 15.0%;P < 0.001). These results su ggest that the degree of attenuation of filtered QRS voltage in the P wave triggered SAECG would be useful for the detection of autonomic ne uropathy.