What effect does vasodilation have on the cardiovascular system in neuro-cardiogenic syncope?

What effect does vasodilation have on the cardiovascular system in neuro-cardiogenic syncope?

• A. Increases heart rate
• B. Decreases the amount of blood returning to the heart
• C. Enhances cardiac contractility
• D. Causes arrhythmias

Answer: (B)

Vasodilation leads to the widening of blood vessels, which can reduce vascular resistance and cause a decrease in blood pressure. In the context of neuro-cardiogenic syncope, this effect of vasodilation is particularly significant because it decreases the amount of blood returning to the heart, also known as venous return. When blood vessels dilate, less blood is able to return to the heart, leading to reduced preload—the volume of blood in the ventricles at the end of diastole.

As a result of this decreased preload, the heart may not pump an adequate volume of blood out to the rest of the body, leading to symptoms such as lightheadedness or fainting. This is a key component of neuro-cardiogenic syncope, where the autonomic nervous system improperly regulates vascular tone and heart rate, leading to transient loss of consciousness due to insufficient cerebral perfusion.

Understanding this response helps in recognizing the physiological processes involved in neuro-cardiogenic syncope and why effective management of vasodilation and blood flow is critical in treating this condition.