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- Kathy E. Sietsema, MD
The presence of intracardiac shunts dissociates the right and left circulations, making dynamic coupling of cellular and pulmonary gas exchange inefficient or impossible. As a result, patients may have profound changes in arterial blood gases and prolongation of adaptation and recovery even with low levels of physical activity. Because the exercise-induced symptoms in patients with cyanotic congenital heart disease have bases apart from heart failure, assignment of a New York Heart Association functional class may be misleading if not erroneous. Dr. Jane Somerville recommends the “Ability Index” shown in Table 1.