Preliminary validation of a non-invasive approach for biomechanical follow-up of heart failure patients

The mismatch between left ventricle and the aorta in Heart Failure patients reduces the energy transfer between the pump and the arterial load. The ventricle, trying to improve its function, changes his shape, the elastance reduces and mechanical coupling with aorta worsens too. On this basis, the measure of the mechanical coupling between ventricle and aorta may represent a good clinical tool to follow, on a scientific basis, the clinical evolution of CHF patients ( which is still a problem!). We propose a new non-invasive approach to evaluate the mechanical coupling between heart and aorta, by comparing the ratio between end systolic ventricular volume and systolic pressure, as an estimate of the end systolic elastance (Ees), and the ratio between stroke volume (SV) and aortic pressure pulse (Pa) as an estimation of the mean arterial elastance (Ea). Aorto-ventricular mechanical matching index (Iav) is calculated by the ratio of Ees and Ea. To test our proposal, 5 patients (3 males and 2 females; mean age: 72 ± 5 years) with HF, submitted to cardiac resynchronisation therapy, were followed periodically to verify if the proposed biomechanical aorto-ventricular matching index, follows the clinical changes. Arterial pressure values were measured non invasively by cuff arterial closure and end systolic ventricular volume was measured by echography. End systolic ventricular pressure was assumed equal to arterial pulse systolic pressure. Successive measurements were performed by the same specialist and repeated to obtain the best assessment avoiding the inter-observer variability. In the limited group of patients the proposed Iav index follows with high sensitivity and coherence the clinical trend of the subjects