Physicians treating heart failure patients know that chronic exertional dyspnea is a classic symptom of heart failure. Because heart failure impacts not only the heart but also the lungs, vasculature, and peripheral muscles, understanding the interaction of these systems is of vital importance.
Other than through cardiopulmonary exercise testing, objective methods of assessing dyspnea are lacking. Standard assessments such as the New York Heart Association classification system and the six-minute walk test are largely subjective and come with significant inter-observer variability and reliance on patient motivation and effort. These assessment methods also lack the sensitivity needed to see subtle changes in patient status that often occur before the onset of overt heart failure symptoms.
Without the objective data on patient physiology, it is often difficult for physicians to see important changes that occur during exercise and that contribute to exertional dyspnea. The ability to unmask exercise-induced changes in pulmonary vascular resistance is a good example.
A main goal of patient therapy is to positively impact dyspnea. But measuring therapy response is nebulous and largely empirical. And, measuring response to specialized therapies—such as CRT or ventricular assist—comes with unique challenges.
Influencers of Dyspnea
Exertional dyspnea is influenced by an array of physiological factors that are reflective of heart failure severity including:
• the cost and work of breathing
• ventilation-perfusion matching in lung
• oxygen uptake, delivery and utilization
• pulmonary blood flow
• gas exchange
“Shape-HF allows us to easily evaluate the patient, diagnose the problem and its severity, and conduct follow up tests to measure the response to treatment. No other test is equivalent.”
Dr. Syed I. Mobin M.D. FCCP, FAASM, Central Florida Pulmonary Group
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