Ventricular stroke work and vascular impedance refine the characterization of patients with aortic stenosis

Abstract

Aortic stenosis (AS) management is classically guided by symptoms and valvular metrics. However, the natural history of AS is dictated by coupling of the left ventricle, aortic valve, and vascular system. We investigated whether metrics of ventricular and vascular state add to the appreciation of AS state above valve gradient alone. Seventy patients with severe symptomatic AS were prospectively followed from baseline to 30 days after transcatheter aortic valve replacement (TAVR). Quality of life (QOL) was assessed using the Kansas City Cardiomyopathy Questionnaire. Left ventricular stroke work (SWLV) and vascular impedance spectrums were calculated noninvasively using in-house models based on central blood pressure waveforms, along with hemodynamic parameters from echocardiograms. Patients with higher preprocedural SWLV and lower vascular impedance were more likely to experience improved QOL after TAVR. Patients fell into two categories: those who did and those who did not exhibit increase in blood pressure after TAVR. In patients who developed hypertension (19%), vascular impedance increased and SWLV remained unchanged (impedance at zeroth harmonic: Z0, from 3964.4 to 4851.8 dyne·s/cm3, P = 0.039; characteristic impedance: Zc, from 376.2 to 603.2 dyne·s/cm3, P = 0.033). SWLV dropped only in patients who did not develop new hypertension after TAVR (from 1.58 to 1.26 J; P < 0.001). Reduction in valvular pressure gradient after TAVR did not predict change in SWLV (r = 0.213; P = 0.129). Reduction of SWLV after TAVR may be an important metric in management of AS, rather than relying solely on the elimination of transvalvular pressure gradients.

A diagnostic, monitoring, and predictive tool for patients with complex valvular, vascular and ventricular diseases

“…This innovative lumped-parameter model calculations were validated against cardiac catheterization data (the instantaneous pressures in the aorta and LV) in forty-nine patients with C3VI (see Results section for validation, Table 1 for patient-specific input parameters and Table 2 for patient's characteristics). Two sub-models (aortic stenosis and aortic regurgitation) have already been used 7,20,21 and validated against in vivo cardiac catheterization (N = 34) 15 and in vivo MRI data (N = 57) 22 . Heart-arterial model.…”

“…Complex valvular-vascular-ventricular interactions (C3VI) is the most general and fundamentally challenging condition in which multiple valvular, vascular and ventricular pathologies have mechanical interactions with one another wherein physical phenomena associated with each pathology amplify effects of others on the cardiovascular system [2][3][4][5][6] . Examples of components of C3VI include: valvular disease (e.g., aortic valve stenosis, mitral valve stenosis, aortic valve regurgitation and mitral valve insufficiency), ventricular disease (e.g., left ventricle dysfunction and heart failure), vascular disease (e.g., hypertension), paravalvular leaks, and LV outflow tract obstruction in patients with implanted cardiovascular devices such as transcatheter valve replacement (TVR), changes due to surgical procedures for C3VI (e.g., valve replacement and left ventricular reconstructive surgery) and etc 2,[4][5][6][7] .…”

Validation study to determine the accuracy of central blood pressure measurement using the SphygmoCor XCEL cuff device in patients with severe aortic stenosis undergoing transcatheter aortic valve replacement

“…Nonetheless, there is no well‐validated quantitative framework integrating the interaction and coupling of left ventricle, aortic valve, and vasculature, which could guide not only who and when to intervene but as to how to optimize treatment following intervention. In order to achieve this landmark milestone, it is key to have reliable methods to estimate the hemodynamic conditions of the patient with AS in a non‐invasive way 6 . In this regard, the central aortic pressure is an essential parameter to be used in these approaches.…”

Towards non-invasive computational-mechanics and imaging-based diagnostic framework for personalized cardiology for coarctation

“…The heart resides in a sophisticated vascular network whose loads impose boundary conditions on the heart function 6,7,[10][11][12] . Effective diagnosis of COA hinges on: (1) quantifications of the global hemodynamics (heart function metrics, e.g., left ventricle workload and instantaneous pressure), and (2) quantifications of the local hemodynamics (detailed information of the 3-D flow dynamics in COA).…”