P2625Pathophysiology of diaphragm involvement in systolic heart failure: insights from diaphragm ultrasound and phrenic nerve stimulation studies

Abstract Background Diaphragm ultrasound allows for assessment of both diaphragm excursion and thickness. Cervical and cortical magnetic stimulation (CEMS and COMS) with recording of the diaphragmatic compound motor action potential (CMAP) is diagnostically useful to evaluate the conductive properties of the inspiratory pathway. Systolic heart failure (HF) is characterized by a loss of systolic pump function. Diaphragm weakness in HF has been reported to potentially contribute to exercise intolerance Methods 14 patients with systolic HF (11 men, 3 women; 64±12 years, NYHA 2±0.9, LVEF 36.1±5.6%) and 12 healthy controls matched for age and gender (4 men, 8 women; 56±8 years) underwent spirometric lung function testing and assessment of diaphragm excursion (during tidal breathing, TB, voluntary sniff, VS and deep breathing, DB) and thickness of the right hemidiaphragm by ultrasound. COMS and CEMS of the phrenic nerves with simultaneous bilateral recording of the diaphragm CMAP using surface electrodes was performed in 9 patients. Results Compared to controls, HF patients showed reduced forced vital capacity (75.46±18.05% vs. 107.62±17.13%, p