血管迷走神経反射と体位性頻脈症候群の関連についての検討

—血管迷走神経反射は体位性頻脈症候群と同義なのか?—

抄録

[Introduction] I encountered a patient in whom signs of the vasovagal reflex (VVR) developed when the patient underwent the Schellong test , and I also published an article describing the appropriate safety measures for performing orthostatic tests in Equilibrium Research vol. 64(1): 22-28. Specifically, we proposed that an orthostatic test should be discontinued as soon as the patient's heart rate met the relevant diagnostic criteria for the postural tachycardia syndrome (POTS). This conclusion was based on the hypothesis that VVR can be considered equivalent to POTS. I then encountered another patient who demonstrated VVR while performing the Schellong test, as described in Practica oto-rhino-laryngologica:.100(5): 341-347. Therefore, the present study was performed to examine the proportion of VVR patients fulfilling the diagnostic criteria for POTS in the course of an orthostatic test. [Subjects] Six patients who were all diagnosed to have dizziness due to VVR. [Methods] The patients were assessed as to whether or not the maximum increase in their heart rate and the absolute maximum heart rate observed during the orthostatic test fulfilled the following two diagnostic criteria for POTS: (A) a 30/min or more increase in heart rate and (B) an absolute heart rate of at least 120 beats/min. [Results] The mean±S.D of absolute heart rate was 73.0±16.6 beats/min at rest and the maximum heart rate 95.7±18.7 beats/min. The mean±S.D. of maximum increase in heart rate was 22.7±7.7 beats/min. Only 1 (16.7%) of the 6 patients tested met the diagnostic criteria for POTS. [Discussion & Conclusion] As the remaining 5 patients failed to meet the diagnostic criteria for POTS, the hypothesis that "VVR can be considered equivalent to POTS" therefore remains questionable. It is thus considered inappropriate to use only the diagnostic criteria for POTS when assessing the safety in patients undergoing an orthostatic test.