About 350,000 Canadians suffer from chronic heart failure (CHF), which can cause premature death. The condition usually progresses slowly as the heart gradually weakens and loses its ability to efficiently pump blood through the body. Patients with CHF develop an enlarged heart and experience “pericardial constraint”: inadequate performance in the ventricles, the heart’s two pumping chambers. The pericardium is a tough, fibrous sac surrounding the heart. Endurance athletes may have an enlarged, more compliant pericardium that allows them to achieve superior levels of cardiac performance during exercise. But with chronic heart failure, the pericardium becomes taut and restricts the heart from fully filling with blood and delivering oxygen to the body. Ben Esch is investigating whether providing oxygen through a mechanical respirator to increase pressure in the chest will decrease pericardial constraint and improve cardiac function in people with CHF. The results could lead to new rehabilitation techniques for patients with chronic heart failure.