Introduction: Pectus excavatum is the result of abnormal development of the chest wall. In this condition, the sternum is depressed inward and compresses cardiac and pulmonary structures of the chest. The impact on cardiac and pulmonary function is highly debated and some argue that the condition is purely cosmetic. Numerous studies looking at cardiac function do suggest an impact on the cardiopulmonary system. Compression of the heart by the chest wall deformity results in shift of the heart leftward. As the heart shifts leftward, compression of the heart moves from right ventricle to right atrioventricular valve and atrium. Our  aim was to determine if an association exists between tricuspid valve (TV) compression and decreased cardiopulmonary function to provide direct evidence that pectus excavatum is more than a cosmetic burden to patients.

Methods: This was a retrospective cohort study of all patients with pectus excavatum at CCHMC between January 2000 and February 2022. Of these patients, only those that were referred to the Chest Wall Center at CCHMC for their pectus excavatum that were included in the study. Cardiopulmonary exercise testing, pulmonary function testing, cardiac MRI functional measurements, and clinical data were combined to complete the full dataset for each patient.  Additional measurements included: TV and mitral valve (MV) measurement on 4 chamber view during diastole, percentage of heart displaced left of midline, cross-sectional area of the TV and MV during peak flow, and a subjective evaluation of the compression of the tricuspid valve. One way analysis of variance was conducted to make comparisons between patients with tricuspid valve compression and those without.

Results: After excluding patients with underlying congenital heart and pulmonary disease, 664 patients were studied. 337 were determined to have TV compression, leaving 327 without TV compression. The average depression of the chest, as determined by the Haller Index, was greater in patients with compression of the tricuspid valve (6.0 ± 2.4 vs. 4.2 ± 0.9, P<0.0001). Right ventricle ejection fraction was 56.0±4.7 in patients without tricuspid valve compression and decreased to 53.2±4.7 in patients with tricuspid valve compression (P<0.0001). Decreased pulmonary function test values were evident in patients with tricuspid valve compression (FVC% of 101.1±13.2 without TV compression vs. 93.7±12.7 with TV compression, P<0.0001; FEV1% of 99.6±12.6 without TV compression vs. 90.8±11.5 with TV compression, P<0.0001). There was no significant difference in cardiopulmonary fitness in patients with tricuspid valve compression when compared to those without, as determined by Peak VO2 (87.6±17.2 vs. 86.4±16.6, P=0.4).

Conclusions: The result of this study provides evidence to describe the physiologic mechanisms involved in patients with severe chest wall compression. Reduced right ventricle ejection fraction and decreased pulmonary function tests are both significant, non-cosmetic outcomes in patients with tricuspid valve compression due to their pectus excavatum.