Effect of Thoracic Paravertebral Block on Heart Rate Variability (HRV)

Effect of Thoracic Paravertebral Block on the Autonomous System as Measured by Heart Rate Variability (HRV)

The Left thoracic paravertebral block have a different effect on heart's autonomic nervous system, as measured with Heart Rate Variability, compared to Right interscalene block

Inclusion Criteria:

• Elective breast surgery
• Age 20 - 65 years
• ASA I - II

Exclusion Criteria:

• Coagulopathy disorders
• Infection at the puncture site for the thoracic paravertebral block
• Severe kyphoscoliosis
• Allergy to local anesthetics
• BMI > 35
• Psychiatric disorders
• Patient's refusal
• Problems with patient communication
• Arrythmia
• Ischaemic heart disease
• Diabetes mellitus
• Thyroid function disorders
• Patients with conduction disorders on the ECG
• Electrolyte disorders (K+, Na+, Ca++)
• Patients on medication that affect the ECG