Influence of thoracic paravertebral block on cardiac repolarization.

The autonomic regulation of cardiac function influences cardiac repolarization, the prolongation of which is associated with life-threatening arrhythmias. This effect can be modified by the pharmacological disruption of conduction in autonomic peripheral nerves. The aim of this study was to determine the influence of thoracic paravertebral blockade (PVB) on the QT interval and transmural dispersion of repolarization (TDR) depending on the side of the block. Sixty females scheduled for unilateral breast surgery were allocated to the study groups according to the site of the operation and underwent PVB at the T3 level with 0.5% ropivacaine. A 12-lead ECG was recorded before the blockade and after confirmation of the block area covering the T1-T4 dermatomes (6-11 min). QT, the corrected QT (QTc), Tp-e (as TDR marker) and Tp-e/QT ratio were analyzed. In the right group significant prolongation of the QT and QTc according to the Fridericia and Framingham formulas was observed, along with significant decreases in heart rate and blood pressure. In the left group no significant repolarization or hemodynamic changes occurred. No significant changes in Tp-e or Tp-e/QT ratio were observed in either group. Due to the short observation period, further studies are needed to fully describe the PVB effect.