What can happen if systemic vascular resistance (SVR) is too low in patients with Eisenmenger Syndrome?

Eisenmenger Syndrome occurs when a left-to-right shunt caused by a congenital heart defect leads to pulmonary hypertension and eventually alters the pressure dynamics within the heart and pulmonary circulation. In this condition, systemic vascular resistance is essential for maintaining appropriate blood flow and pressure.

When systemic vascular resistance is too low, there can be a significant impact on the shunting of blood. The decrease in SVR can cause a shift in the pressure gradient between the right and left sides of the heart. In patients with Eisenmenger Syndrome, a low systemic vascular resistance promotes a worsening of the right-to-left shunt. This is because the pressures in the right side of the heart, particularly in the context of elevated pulmonary artery pressures that are characteristic of Eisenmenger, may become insufficient to maintain the left-to-right flow, allowing deoxygenated blood to flow directly from the right heart into systemic circulation.

As a consequence of this worsening right-to-left shunt, the individual experiences a drop in oxygenation because deoxygenated blood is now being delivered systemically. This can lead to hypoxemia and cyanosis, which are common symptoms of advanced Eisenmenger Syndrome. Therefore, in this scenario, low SVR can adversely affect the shunting dynamics, resulting