Heart rate variability during chemical thoracic sympathectomy

Area of Science:

• Cardiology
• Autonomic Nervous System Research
• Pain Management

Background:

• Chemical thoracic sympathectomy (CTS) is used for neuralgia but can cause profound bradycardia.
• The cause of bradycardia following CTS was investigated using heart rate variability analysis.
• Poincaré plots were employed to assess cardiac sympathetic activity before and after procedures.

Observation:

• Heart rate variability was assessed in patients undergoing CTS (n=13) and mandibular block (MB, n=10).
• The SD(RR):SDdeltaRR ratio, a measure of cardiac sympathetic activity, was evaluated.
• A significant decrease in the SD(RR):SDdeltaRR ratio was observed immediately after CTS in the CTS group.

Findings:

• The SD(RR):SDdeltaRR ratio decreased significantly post-CTS, indicating reduced cardiac sympathetic activity.
• No significant heart rate changes were noted in either the CTS or MB groups.
• A patient with a high pre-CTS SD(RR):SDdeltaRR ratio (3.45) experienced severe bradycardia (22 bpm).

Implications:

• A decrease in the SD(RR):SDdeltaRR ratio post-CTS suggests reduced cardiac sympathetic tone.
• Patients with high baseline SD(RR):SDdeltaRR ratios may be at risk for profound bradycardia after CTS.
• Pre-procedural assessment of cardiac sympathetic activity using Poincaré plots may help identify patients at risk for bradycardia during CTS.