A significant non-invasive indicator of autonomic ner- vous system (ANS) function is heart rate variability (HRV). The distribution of beat-to-beat variations may not be cap- tured by conventional HRV analysis, which uses continu- ous variables to measure total variability. In this work, we investigate the adaptability of HRV to controlled au- tonomic disturbances and propose a symbolic represen- tation of HRV based on discretized magnitudes of beat- to-beat RR interval (RRI) changes. Six healthy individ- uals' Electrocardiogram (ECG) recordings were exam- ined at baseline, during β-adrenergic blockade (propra- nolol), and during parasympathetic blockade (atropine). The log-transformed beat-to-beat RRI discrepancies were discretized into seven symbolic levels (S0–S6) that corre- sponded to increasing HR change magnitudes. The Wilcoxon Signed-Rank test was used to compare symbol distributions amongst conditions. A significant shift toward lower-magnitude alterations was caused by parasympathetic blockade, with higher-magnitude sym- bols (S5–S6) being suppressed and S0–S1 occurring more frequently (p < 0.05). β-adrenergic blockade, on the other hand, showed very little alteration. The interme- diate symbols remained unchanged significantly. These results imply that autonomic modulation does not con- sistently change the degree of beat-to-beat variability but rather redistributes the degree of variability. In addition to traditional measurements, symbolic HRV offers a physi- ologically interpretable framework that could enhance the identification of autonomic dysfunction.