Heart rate variability in patients with atrioventricular block

Area of Science:

• Cardiology
• Autonomic Nervous System Physiology
• Medical Instrumentation

Background:

• Heart rate variability (HRV) analysis assesses autonomic nervous system activity.
• Conventional HRV uses RR intervals from surface ECG, which is unsuitable for patients with atrioventricular (AV) block.
• Esophageal electrode use for PP intervals offers an alternative for HRV analysis in these patients.

Purpose of the Study:

• To evaluate the efficacy of esophageal lead recordings for HRV analysis in patients with AV block.
• To compare HRV parameters derived from esophageal ECG with those from conventional ECG methods in AV block patients.

Main Methods:

• Seven AV block patients and 13 controls underwent simultaneous esophageal, surface, and intraatrial ECG recordings.
• Correlation coefficients were calculated for heart beat intervals from different leads.
• HRV parameters were compared between AV block patients and controls using esophageal lead data.

Main Results:

• Esophageal ECG (PP intervals) showed high correlation with intraatrial ECG (AA intervals) (r=0.968) in AV block patients, unlike surface ECG (r=0.489).
• Time-domain HRV parameters, including SDNN, pNN-50, and r-MSSD, were significantly decreased in AV block patients compared to controls.
• Esophageal lead recordings demonstrated reduced HRV in AV block patients, indicating abnormal vagal activity.

Conclusions:

• Esophageal lead ECG is a non-invasive, safe, and effective method for HRV assessment in AV block patients.
• This technique overcomes limitations of surface ECG in patients with AV node dysfunction.
• Esophageal HRV analysis provides valuable insights into autonomic function in complex cardiac conditions.