Related Experiment Videos
Sympathetic nervous system tonicity and post-coronary artery bypass hypertension
Insights
Post-coronary bypass surgery hypertension is linked to initial increases in plasma norepinephrine (NE). However, surgery stress elevates catecholamines in all patients, regardless of blood pressure changes.
Area of Science:
- Cardiovascular Surgery
- Hypertension Pathogenesis
- Neuroendocrinology
Background:
- Coronary bypass surgery (myocardial revascularization) can lead to post-operative hypertension.
- The precise mechanisms underlying this hypertension remain incompletely understood.
- Elevated plasma catecholamines are suspected contributors to post-surgical hemodynamic changes.
Purpose of the Study:
- To investigate the relationship between plasma catecholamine levels and the development of hypertension after coronary bypass surgery.
- To determine if specific catecholamine responses correlate with post-operative blood pressure changes.
- To assess the impact of myocardial revascularization surgery on adrenergic activity.
Main Methods:
- Blood pressure and plasma catecholamine concentrations (norepinephrine and epinephrine) were measured in 28 coronary artery disease patients.
- Measurements were taken pre-operatively and at 1 and 4 hours post-surgery.
- Patients were categorized based on post-operative blood pressure (hypertensive vs. normotensive).
Main Results:
- Plasma norepinephrine (NE) significantly increased 1 hour post-surgery in patients who developed hypertension.
- This initial NE increase was not observed in normotensive patients.
- Both hypertensive and normotensive groups showed significant NE and epinephrine (E) increases at 4 hours post-surgery, irrespective of blood pressure.
- Surgery acts as a potent adrenergic stimulus.
Conclusions:
- Early post-operative hypertension following coronary bypass surgery may be associated with a specific surge in plasma norepinephrine.
- Surgical stress significantly elevates plasma catecholamines in all patients undergoing myocardial revascularization.
- The broader hemodynamic implications of these catecholamine changes post-surgery require further investigation.
Abstract:
To elucidate the pathogenesis of hypertension following coronary bypass surgery, blood pressure and plasma catecholamine concentration were measured in 28 patients with coronary artery disease who were undergoing myocardial revascularization procedures. Measurements were obtained on arrival in the operating room and 1 and 4 h after surgery. One hour after surgery, plasma norepinephrine (NE) increased significantly by 495 +/- 108 pg/ml (P less than 0.001) in the coronary artery disease group which developed hypertension, but the increase was not significant in the coronary artery patients who remained normotensive after surgery. However, 4 h after surgery, plasma NE increased significantly and to the same extent in both coronary artery disease groups, regardless of the change in blood pressure. Plasma epinephrine (E) also increased significantly 1 and 4 h after surgery in both groups. The observed change in plasma catecholamine concentration is direct evidence that the stress of surgery is a potent adrenergic stimulus, but the hemodynamic significance of the plasma catecholamine change remains unclear.