Cardioventilatory coupling in atrial fibrillation

Area of Science:

• Physiology
• Cardiorespiratory Interactions
• Autonomic Nervous System

Background:

• Cardioventilatory coupling describes the temporal coherence between heart and breathing rhythms.
• This phenomenon is observed during rest, sleep, and anesthesia.
• Several graphical methods exist to study this entrainment, each with different mechanistic assumptions.

Purpose of the Study:

• To compare five graphical methods for studying cardioventilatory coupling.
• To investigate the temporal relationship between heartbeats and breathing in elderly subjects with atrial fibrillation under anesthesia.
• To determine the most accurate model describing cardioventilatory coupling.

Main Methods:

• Recorded heart period and ventilatory time series in eight elderly subjects with atrial fibrillation during general anesthesia.
• Compared five distinct graphical methods to assess cardioventilatory coupling.
• Analyzed the temporal relationship between inspiration and preceding/following heartbeats, cardiac/ventilatory cycle phases, and relative phases.

Main Results:

• Cardioventilatory coupling was observed in seven out of eight subjects.
• The relationship between inspiration and a preceding heart beat provided the best qualitative and quantitative description of coupling.
• The interval variation between inspiration and a preceding heart beat was minimal compared to other methods.

Conclusions:

• The findings support a model where a heartbeat triggers inspiration.
• This suggests a causal relationship where cardiac activity influences ventilation onset.
• The study refutes models of cardiac timing modulation by ventilation or simple phase relationships.