In single-ventricle physiology, which ventricle is described as the dominant ventricle?

• A. The ventricle that pumps to the pulmonary artery.
• B. The ventricle that supplies the systemic circulation and pumps to the aorta.
• C. The smaller ventricle.
• D. The ventricle with thicker walls.

Answer: (D)

In single-ventricle physiology, the ventricle that acts as the dominant one is the more muscular chamber—the one with thicker walls. Thicker walls mean greater contractile strength and ability to generate higher systolic pressures to overcome systemic afterload, so this ventricle takes on the systemic “workhorse” role. The description isn’t about which ventricle pumps to the pulmonary artery or about size alone; it’s about muscularity and capacity to sustain systemic circulation.