MICROANATOMY

Detailed explanation-1: -It is concluded that an increased blood viscosity due to polycythemia significantly alters the pulmonary hemodynamics of patients with congenital heart disease with either increased or decreased pulmonary blood flow.

Detailed explanation-2: -As Hct increases, viscosity increases, elevating vascular resistance and decreasing blood flow at any given perfusion pressure. As Hct rises above 60%, viscosity tends to increase exponentially.

Detailed explanation-3: -The most common causes of secondary polycythemia include obstructive sleep apnea, obesity hypoventilation syndrome, and chronic obstructive pulmonary disease (COPD). Other causes include testosterone replacement therapy and heavy cigarette smoking.

Detailed explanation-4: -An increase in blood viscosity can be caused either by a deformity of the shape of red blood cells (RBCs) which causes RBC aggregation and decreased blood flow or by any pathological elevation of the components of blood. This includes RBC, WBC, platelets, or serum proteins.