Related Experiment Videos
Responses of heart rate variability to coronary occlusion during coronary angioplasty
K E Airaksinen1, M J Ikäheimo, H V Huikuri
1Department of Medicine, University of Oulu, Finland.
Insights
Coronary occlusion triggers immediate heart rate variability changes in over a third of patients. These autonomic responses, indicating sympathetic or parasympathetic shifts, are unpredictable based on the occlusion site.
Area of Science:
- Cardiology
- Autonomic Nervous System Research
- Medical Physiology
Background:
- Autonomic nervous system (ANS) activity influences heart rate (HR) and is implicated in acute myocardial infarction (AMI).
- Sympathetic activation is typical in anterior wall AMI, while parasympathetic reflexes dominate in inferior wall AMI.
- Immediate ANS responses to coronary occlusion are not fully understood.
Purpose of the Study:
- To assess immediate autonomic responses to acute coronary occlusion using heart rate variability (HRV) measures.
- To determine if the site of coronary occlusion predicts the direction of initial HRV changes.
Main Methods:
- Analyzed frequency and time domain HRV measures (high-frequency power, root-mean-square successive difference) in 73 patients with significant coronary artery stenosis.
- Measured HRV immediately before and during brief balloon occlusion (mean 99 seconds) of coronary arteries.
- Established a range of nonspecific HRV changes using a control group (16 patients) without ischemia during dilatations.
Main Results:
- Coronary artery occlusion induced immediate changes in HRV in over one-third of patients.
- Left anterior descending artery occlusion (n=35) resulted in increased HRV (vagal activation) in 23% and decreased HRV in 11%.
- Left circumflex (n=19) and right coronary artery (n=19) occlusions showed similar HRV alteration patterns, with increased HRV in 26% and decreased HRV in 11-21%.
Conclusions:
- Acute coronary occlusion provokes rapid and significant alterations in heart rate variability.
- The observed HRV changes suggest immediate autonomic nervous system responses.
- The specific site of coronary occlusion does not reliably predict the direction of these initial HRV changes.
Abstract:
Signs of sympathetic activation are frequent during the early hours of anterior wall acute myocardial infarction, whereas parasympathetic reflexes predominate in inferior wall acute myocardial infarction. To assess the immediate autonomic responses to acute coronary occlusion, the high-frequency power and root-mean-square successive difference, frequency and time domain measures of heart rate (HR) variability were analyzed in 73 cases of significant (50 to 95%) coronary artery stenosis immediately before and during balloon occlusion (mean 99 seconds). The range of nonspecific changes was formed on the basis of a control group with no ischemia during dilatations of 16 totally occluded coronary arteries. Balloon occlusion of the left anterior descending artery (n = 35) caused an abnormal increase in the measures of HR variability as a sign of vagal activation in 8 patients (23%), and a significant decrease in HR variability in 4 (11%). Occlusion of the left circumflex artery (n = 19) caused an increase in HR variability in 5 patients (26%), and a decrease in 2 (11%). Right coronary artery occlusion (n = 19) caused an increase in HR variability in 5 patients (26%) and a decrease in 4 (21%). Thus, coronary occlusion causes immediate changes in HR variability in greater than one third of patients with coronary artery disease. The direction of these initial HR variability changes cannot be predicted by the site of coronary occlusion.