A 45-year-old Indian male presents with progressive abdominal distension, jaundice, and ascites over 3 months. Imaging reveals thrombosis of all three hepatic veins. On CT abdomen with contrast, the liver shows diffuse atrophy of the right and left lobes, but the structure marked **A** (caudate lobe) is notably enlarged and hypertrophied. Which of the following best explains the preservation and hypertrophy of the caudate lobe in this clinical scenario?