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Stroke volume variability--cardiovascular response to orthostatic maneuver in patients with coronary artery diseases
J Siebert1, J Wtorek, J Rogowski
1First Department of Cardiology and Cardiosurgery, Medical University of Gdañsk, Poland.
Insights
Coronary artery bypass grafting (CABG) significantly reduces stroke volume variability (SVV) in the standing position. This indicates CABG impacts cardiovascular autonomic regulation during postural changes.
Area of Science:
- Cardiovascular Physiology
- Autonomic Nervous System Regulation
- Surgical Impact on Hemodynamics
Background:
- Cardiovascular responses to postural stress are complex and not fully understood.
- Postural changes challenge the autonomic nervous system's ability to maintain hemodynamic stability.
- The specific effects of coronary artery bypass grafting (CABG) on cardiovascular autonomic regulation remain unclear.
Purpose of the Study:
- To investigate the impact of coronary artery bypass grafting (CABG) on stroke volume variability (SVV).
- To analyze changes in the power spectrum components of SVV before and after CABG.
- To assess the influence of CABG on cardiovascular autonomic responses to postural stress.
Main Methods:
- Sixty patients undergoing CABG were studied before and 6 weeks after surgery.
- Stroke volume variability (SVV) was measured using thoracic bioimpedance.
- Power spectrum analysis (autoregressive method) of SVV was performed in supine and standing positions with controlled breathing.
Main Results:
- No significant changes in stroke volume spectral power indices were observed before CABG.
- Following CABG, all analyzed spectral indices of SVV significantly decreased in the standing position.
- This suggests a diminished sympathetic or baroreflex-mediated modulation of stroke volume post-CABG during postural challenges.
Conclusions:
- Coronary artery bypass grafting (CABG) alters cardiovascular autonomic regulation, specifically reducing stroke volume variability (SVV) during postural stress.
- The findings highlight a potential long-term effect of CABG on the dynamic cardiovascular response to standing.
- Further research is warranted to elucidate the clinical implications of these observed changes in SVV post-CABG.
Abstract:
The dynamics of cardiovascular responses to postural stress have not been fully recognized. To determine whether coronary artery bypass grafting (CABG) has any effect on stroke volume variability (SVV), the power spectrum components of SVV were measured in 60 patients before and at 6 weeks after CABG. Stroke volume was assessed by means of the thoracic bioimpedance method. The thoracic impedance cardiogram and ECG were recorded in the supine and standing positions with controlled breathing rate (0.25 Hz) during 10-minute periods. The analysis of SVV was done by means of the autoregressive method. The total power, the power in the low-frequency band LFSV (0.05-0.15 Hz), the power in the high-frequency band HFSV (0.15-0.5 Hz), and the LFSV/HFSV ratio were analyzed. Before CABG, we did not notice any significant changes in the stroke volume spectral power indices. After CABG, all spectral indices were significantly decreased in the standing position.