Assessment of Conventional Autonomic Function Tests in Patients with Acute Intermittent Porphyria

Abstract

Background and Aim: To assess the autonomic nerve functions in latent and manifest patients of acute intermittent porphyria. The aim of the present study was to study cardiovascular responses to autonomic nerve functions in patients of acute intermittent porphyria, we also tried to find out the relative sensitivity of the various tests employed to study cardiac dysautonomia in these cases. Methods: The study was carried out on thirty cases of acute intermittent porphyria to assess the cardiovascular reflexes. Twenty five healthy subjects closely matched for age and sex served as control. The cases were diagnosed by modified Watson Schwartz test, the cases of acute intermittent porphyria were divided into three groups. Results: The values of different autonomic nerve function tests were compared with control group and among the different groups of patients. The results were complied, compared and a conclusion was drawn. Immediate heart rate response to standing is more sensitive test than the Valsalva maneuver. Immediate heart rate response to standing is more sensitive and quite reliable which can easily be performed at bed side or even in outpatient departments, the test is simple and non-invasive. In our opinion, the test, beat to beat variation of heart rate to single deep breath is though easy to perform and more understandable, but lacks the sensitivity of other two tests. Conclusion: Significant cardiac dysautonomia is present in asymptomatic group, it is more marked in acute attack group. Immediate heart rate response to standing could be a more sensitive and reliable test in this dysfunction.