A non-invasive biomechanical approach to the clinical follow-up of heart failure patients

The mismatch between the left ventricle and the aorta in heart failure (HF) patients progressively reduces the energy transfer efficiency between the pump and the load. To evaluate the evolution in time of the mechanical coupling between ventricle and aorta, the aorto-ventricular mechanical matching index (Iav) is calculated as the ratio between the ventricular end systolic elastance and the mean aortic elastance during ejection. Iav was tested on eight HF patients submitted to cardiac resynchronisation therapy, during the standard clinical follow-up. Moreover, three healthy control subjects were investigated. Pressure values were measured by arm cuff arterial closure. End systolic ventricular volume was measured by echocardiography. Stroke volume was measured by transthoracic impedance. End systo lic ventricular pressure was assumed equal to arterial systolic pressure. In the normal subjects, the Iav index presented a long-term dispersion less than 0.2. In the group of patients, the Iav index showed dispersion from 0.49 to 2.57, much larger than the resolution limit. The proposed Iav demonstrated a good sensitivity for monitoring the evolution of HF patients. As it is non-invasive, this approach could be an alternative or adjunct method transforming the traditional “subjective” clinical evaluation of HF patients into to a “scientific” instrumental approach.