Externally Applied Pneumatic Compression as a Therapy for Fontan Patients
Authors:   , Tse Tiffany K. , Throckmorton Amy 
Published: July 2021

Single ventricular defects of the heart occur in 5 out of 100,000 live births. This type of congenital heart defect does not provide a sustainable circulatory system for the patients affected. Starting at infancy, patients undergo a three-part surgical paradigm to create a circulation necessary for survival. The patients who complete the surgical paradigm are known to have attained a Fontan circulation or physiology. Although the Fontan circulation allows patients to survive, this man-made physiology is associated with complications such as exercise intolerance, low cardiac output, cardiac arrhythmias, and protein-loss enteropathy. In addition, Fontan patients are at high risk of developing premature congenital heart failure (CHF). Currently, there are no non-invasive solutions to alleviate the risks and complications associated with a failing Fontan. The long-term objective of this research is to study the potential benefits of externally applied compression on patients with the Fontan circulation. The application of external compression in a pulsatile fashion to the lower extremities may imitate the pumping action that results from the contraction and extension of musculature during exercise to augment blood flow. In addition, similar technology involving the use of external compression such as medical anti-shock trousers (MAST) and enhanced external counterpulsation therapy (EECP) has shown to improve cardiovascular conditions in previous studies. The purpose of this study is to introduce externally applied compression as a non-invasive means to augment blood flow and venous return from the lower extremities to the heart, ideally improving ventricular filling and thus, cardiac output. As this is an exploratory study, it aims to also better understand pneumatic compression technology and the compression settings best tolerated by adults with a normal cardiovascular circulation. The NormaTec Pneumatic Compression Device (PCD) was used in an IRB approved study on healthy adult subjects (n=25) to assess the comfort level of predetermined magnitude (mmHg) and frequency (cycles per second) settings of the device. Five different combinations varying in magnitude and frequency of compression were applied on each subject. The universal pain scale (1 to 10) was used to rate subject comfort and an Exit Interview Survey was conducted afterwards to evaluate subject feedback. Pain scale responses greater than 2 correlated to discomfort that was more than mild ("Significant") while responses of 2 or less correlated with no pain or mild discomfort ("Insignificant"). Thirteen out of the 25 subjects consistently answered with pain scale values of 2 or less for all 5 compression levels. Three out of the 25 subjects consistently responded with values greater than 2 for all 5 compression levels. We aimed to characterize subject types (Insensitive, Highly Insensitive, Sensitive, and Highly Sensitive) based on their responses to the overall compression treatment. Findings concluded that pain scale responses generally varied among subjects. Based on the comfort assessment and Exit Interview Survey results, the externally applied compression was well received overall with minimal pain and discomfort. Future studies intend to investigate the effects of pneumatic compression on Fontan patients using MRI technology.