Final answer:
Phosphodiesterase inhibitors, besides providing a positive inotropic effect in heart failure management, additionally cause vasodilation, reducing the workload on the heart by widening the blood vessels.
Step-by-step explanation:
Phosphodiesterase inhibitors (PDIs) have a significant role in treating heart failure due to their ability to cause a positive inotropic effect. The positive inotropic effect leads to increased strength of heart muscle contractions by influencing calcium levels within cardiac cells. An added advantage of PDIs, aside from their inotropic properties, is that they cause vasodilation. Vasodilation refers to the widening of blood vessels, which reduces vascular resistance and aids in decreasing the workload on the heart. This pharmacologic effect, exemplified in drugs such as sildenafil, emerges from the inhibition of the enzyme phosphodiesterase that leads to an increased concentration of cyclic guanosine monophosphate (cGMP) in vascular smooth muscle, causing relaxation and vasodilation.