vi medicine informatics




Norepinephrine administration will result in increased venous return to the heart through vasoconstriction in conjunction with increased heart contractility, producing an increase in stroke volume (SV). Because the heart no longer needs to beat as quickly to maintain sufficient cardiac output (CO) (as CO = SV × Heart rate), there is a reflex decrease in heart rate. This is known as the reflex bradycardia effect of norepinephrine. Because norepinephrine acts with greater affinity for α-adrenergic receptors than β-adrenergic receptors, this reflex bradycardia in response to α1-mediated vasoconstriction outweighs any β1-mediated increase in heart rate, resulting in a net decrease in heart rate. In addition, administration of norepinephrine can be expected to result in an increase in both systolic and diastolic blood pressure

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