IMT associated with Improved Inspiratory Muscle Strength in Fontan Circulation patients

Like other forms of heart failure, low cardiac output and raised central venous pressure is what characterises the Fontan Circulation. However unlike other forms of heart failure, in Fontan circulation patients the primary limitation is absence of a subpulmonary ventricle.

Affects of Fontan circulation

Patients will experience reduced exercise capacity and respiratory muscle strength. Fortunately Inspiratory Muscle Training (IMT) improves exercise capacity and quality of life in adults with heart failure. This is evident from previous studies.

Purpose and method of study

The purpose of this study is to assess whether a home-based IMT program improves inspiratory muscle strength and the ventilatory efficiency of exercise in adolescent patients with a Fontan circulation.

To assess this, Fontan circulation patients underwent 30 minutes of IMT daily for six weeks. Exercise capacity (cardiopulmonary exercise testing), lung function and respiratory muscle strength (maximal inspiratory pressure and expiratory pressure) are all assessed.

Study findings

Findings from the study show that IMT is a simple and beneficial addition to the management of Fontan patients. It shows that IMT potentially reduces exercise intolerance and long-term morbidity and mortality.


The study shows that six weeks of IMT is associated with improving inspiratory muscle strength, ventilatory efficiency of exercise, and resting cardiac output in young Fontan patients.

The study

Inspiratory Muscle Training Is Associated With Improved Inspiratory Muscle Strength, Resting Cardiac Output, and the Ventilatory Efficiency of Exercise in Patients With a Fontan Circulation >

Improving Functional Capacity in Fontan Patients Through IMT

This study, sponsored by Children’s Hospital Boston, is currently recruiting participants for this clinical trial, the purpose of which is to study the effects of Inspiratory Muscle Training (IMT) on exercise and pulmonary function parameters in a cohort of adult Fontan patients.

According to The Ahmanson/UCLA Adult Congenital Heart Disease Center in the U.S., “the Fontan procedure is a surgical procedure performed for single ventricle physiology. Patients with single ventricle physiology have hearts with only one effective pumping chamber that delivers blood to both the body and the lungs.

Because there is only one ventricle instead of two, blood without oxygen mixes with oxygenated blood in this single chamber, so the oxygen content of the blood going to the body is considerably lower than normal. Uncorrected, this leads to long term cyanosis (or blueness), and associated issues such as exercise intolerance, elevated blood pressures in the lungs, abnormally high red blood cell counts and bleeding disorders, to name a few.

The Fontan operation allows for separation of the two circulations by re-routing under-oxygenated blood from the body directly to the blood vessels that lead to the lungs, thereby allowing the single ventricle to pump only oxygenated blood to the body. This creates a more normal circulation, and reduces the complications described above.”

The investigators of this new clinical study hypothesize that a 12-week program of inspiratory muscle training (IMT) with an inspiratory impedance threshold device will improve inspiratory muscle strength and endurance, and that this will translate into improved exercise performance in patients with Fontan physiology.

Read more about the clinical trial here >

Check out more Inspiratory Muscle Training Research here >

Discover POWERbreathe used in Research here >