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Sympathetic stimulation using the cold pressor test increases coronary collateral flow
S F de Marchi1, M Schwerzmann, M Billinger
1Swiss Cardiovascular Center Bern, University Hospital, Bern, Switzerland.
Insights
Coronary collateral flow increases with sympathetic stimulation from the cold pressor test (CPT). This sympathetic stimulation augments collateral flow, comparable to occlusion effects, suggesting vasodilation.
Area of Science:
- Cardiovascular Physiology
- Coronary Artery Disease Research
- Autonomic Nervous System Function
Background:
- The vasomotor function of human coronary collateral vessels remains poorly understood.
- Investigating collateral flow under sympathetic stimulation is crucial for understanding coronary artery disease (CAD) pathophysiology.
Purpose of the Study:
- To examine the impact of sympathetic stimulation, specifically the cold pressor test (CPT), on human coronary collateral vessel flow.
- To quantify changes in collateral flow index (CFI) during CPT in patients with CAD.
Main Methods:
- Thirty patients with CAD underwent two coronary artery occlusions, with CPT randomly applied during one occlusion.
- Collateral flow index (CFI) was calculated using aortic pressure (Pao), central venous pressure (CVP), and coronary wedge pressure (Poccl).
- CPT involved immersing the patient's hand in ice water for 1 minute before and during occlusion.
Main Results:
- CPT significantly increased mean aortic pressure (Pao).
- Collateral flow index (CFI) increased significantly during occlusion, both with and without CPT.
- CFI was significantly higher during CPT compared to control occlusions at all time points.
Conclusions:
- Coronary collateral flow increases due to collateral recruitment during occlusion, independent of external sympathetic stimulation.
- Sympathetic stimulation via CPT further augments collateral flow, indicating a role for the sympathetic nervous system.
- The observed coronary collateral vasodilation suggests a mechanism mediated by sympathetic nervous system activation.
Background:
Little is known about the vasomotor function of human coronary collateral vessels. The purpose of this study was to examine collateral flow under a strong sympathetic stimulus (cold pressor test, CPT).
Methods:
In 30 patients (62 +/- 12 years) with coronary artery disease, two subsequent coronary artery occlusions were performed with random CPT during one of them. Two minutes before and during the 1 minute-occlusion, the patient's hand was immerged in ice water. For the calculation of a perfusion pressure-independent collateral flow index (CFI), the aortic (Pao), the central venous (CVP) and the coronary wedge pressure (Poccl) were measured: CFI = (Poccl - CVP)/(Pao - CVP).
Results:
CPT lead to an increase in Pao from 98 +/- 14 to 105 +/- 15 mm Hg (p = 0.002). Without and with CPT, CFI increased during occlusion from 14% +/- 10% to 16% +/- 10% (p = 0.03) and from 17% +/- 9% to 19% +/- 9% (p = 0.006), respectively, relative to normal flow. During CPT, CFI was significantly higher at the beginning as well as at the end of the occlusion compared to identical instants without CPT. CFI at the end of the control occlusion did not differ significantly from the CFI at the beginning of occlusion with CPT.
Conclusions:
During balloon occlusion, collateral flow increased due to collateral recruitment independent of external sympathetic stimulation. Sympathetic stimulation using CPT additionally augmented collateral flow. The collateral-flow-increasing effect of CPT is comparable to the recruitment effect of the occlusion itself. This may reflect a coronary collateral vasodilation mediated by the sympathetic nervous system.