Abstract Background Intraventricular fluid dynamics can be assessed clinically using imaging. The contribution of vortex structures to left ventricular (LV) diastolic function has never been ...quantified in vivo. Objectives This study sought to understand the impact of intraventricular flow patterns on filling and to assess whether impaired fluid dynamics may be a source of diastolic dysfunction. Methods Two-dimensional flow velocity fields from color Doppler echocardiographic sequences were obtained in 20 patients with nonischemic dilated cardiomyopathy (NIDCM), 20 patients with hypertrophic cardiomyopathy (HCM), and 20 control healthy volunteers. Using a flow decomposition method, we isolated the rotational velocity generated by the vortex ring from the surrounding flow in the left ventricle. Results The vortex was responsible for entering 13 ± 6% of filling volume in the control group and 19 ± 8% in the NIDCM group (p = 0.004), but only 5 ± 5% in the HCM group (p < 0.0001 vs. controls). Favorable vortical effects on intraventricular pressure gradients were observed in the control and NIDCM groups but not in HCM patients. Differences in chamber sphericity explained variations in the vortex contribution to filling between groups (p < 0.005). Conclusions The diastolic vortex is responsible for entering a significant fraction of LV filling volume at no energetic or pressure cost. Thus, intraventricular fluid mechanics are an important determinant of global chamber LV operative stiffness. Reduced stiffness in NIDCM is partially related to enhanced vorticity. Conversely, impaired vortex generation is an unreported mechanism of diastolic dysfunction in HCM and probably other causes of concentric remodeling.
Abstract Objectives The goal of this study was to determine the functional impact of paradoxical low-gradient aortic stenosis (PLGAS) and clarify whether the relevance of the valvular obstruction is ...related to baseline flow. Background Establishing the significance of PLGAS is particularly challenging. Methods Twenty symptomatic patients (77 ± 6 years of age; 17 female subjects) with PLGAS (mean gradient 28 ± 6 mm Hg; aortic valve area 0.8 ± 0.1 cm2 ; ejection fraction 66 ± 7%) underwent cardiopulmonary exercise testing combined with right-heart catheterization and Doppler echocardiographic measurements. Results Aortic valve area increased by 84 ± 23% (p < 0.001) and, in 70% of subjects, it reached values >1.0 cm2 at peak exercise. Stroke volume index and blood pressure increased by 83 ± 56% and 26 ± 16%, respectively (both p < 0.0001). Peak oxygen consumption inversely correlated with the rate of increase in pulmonary capillary wedge pressure (PCWP) (PCWP slope: R = –0.61; p = 0.004). In turn, the PCWP slope was determined by changes in the valvular and vascular load but not by the rest of the indices of aortic stenosis. The functional impact of PLGAS was also not related to baseline flow. Agreement between Doppler echocardiography and the Fick technique was good up to intermediate workload. Conclusions In symptomatic patients with PLGAS, the capacity to dynamically reduce vascular and valvular loads determines the effect of exercise on PCWP, which, in turn, conditions the functional status. A critically fixed valvular obstruction may not be the main mechanism of functional impairment in a large proportion of patients with PLGAS. Exercise echocardiography is suitable to study the dynamics of PLGAS.
Abstract Background Systemic arterial load impacts the symptomatic status and outcome of patients with calcific degenerative aortic stenosis (AS). However, assessing vascular properties is ...challenging because the arterial tree’s behavior could be influenced by the valvular obstruction. Objectives This study sought to characterize the interaction between valvular and vascular functions in patients with AS by using transcatheter aortic valve replacement (TAVR) as a clinical model of isolated intervention. Methods Aortic pressure and flow were measured simultaneously using high-fidelity sensors in 23 patients (mean 79 ± 7 years of age) before and after TAVR. Blood pressure and clinical response were registered at 6-month follow-up. Results Systolic and pulse arterial pressures, as well as indices of vascular function (vascular resistance, aortic input impedance, compliance, and arterial elastance), were significantly modified by TAVR, exhibiting stiffer vascular behavior post-intervention (all, p < 0.05). Peak left ventricular pressure decreased after TAVR (186 ± 36 mm Hg vs. 162 ± 23 mm Hg, respectively; p = 0.003) but remained at >140 mm Hg in 70% of patients. Wave intensity analysis showed abnormally low forward and backward compression waves at baseline, increasing significantly after TAVR. Stroke volume decreased (−21 ± 19%; p < 0.001) and correlated with continuous and pulsatile indices of arterial load. In the 48 h following TAVR, a hypertensive response was observed in 12 patients (52%), and after 6-month follow-up, 5 patients required further intensification of discharge antihypertensive therapy. Conclusions Vascular function in calcific degenerative AS is conditioned by the upstream valvular obstruction that dampens forward and backward compression waves in the arterial tree. An increase in vascular load after TAVR limits the procedure’s acute afterload relief.
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