Cardiac Performance, Ventricular-Vascular Interaction and Functional Alterations in Rheumatic Mitral Stenosis : A descriptive study employing novel hemodynamic and echocardiographic modalities
Abstract: The assessment of LV performance poses significant challenges in the setting of rheumatic mitral stenosis (MS) owing to an inherently load-altered state. A detailed characterization of arterial-ventricular coupling between subjects with isolated post-capillary pulmonary hypertension (Ipc-PH) and combined pre- and post-capillary pulmonary hypertension (Cpc-PH) has not been described. Diastolic pulmonary pressure gradient (DPG) has come under scrutiny owing to the occurrence of negative DPG values, and its prognostic implications are obscure. Mitral Annular (MA) geometry and alterations associated with successful percutaneous intervention remain unclear. The studies in this thesis aim to provide insights into these aspects of MS using novel hemodynamic and echocardiographic modalities.In Study I, load-independent indices of LV performance were analysed using the single-beat method in 106 MS subjects employing simultaneous bi-ventricular catheterization and echocardiography. MS subjects showcased significantly elevated arterial load, LV contractility and stiffness as compared with controls. Afterload was inversely associated with the severity of stenosis. Both LV elastance (Ees) and arterial elastance (Ea) returned to more normal levels immediately after PTMC, while LV stiffness demonstrated a further rise. In Study II, systemic arterial-ventricular (AV) coupling was analysed in PH subjects among 106 MS patients. Compared with Ipc-PH subjects, Cpc-PH group demonstrated elevated Ea and Ea/Ees ratio. Ea was associated with reduced LV deformation in both septal and lateral LV segments. Impact of the RV on the LV was limited to the septum. In Study III, 316 subjects with left heart disease (LHD) due to primary myocardial dysfunction or valvular disorders were studied to clarify the physiological and prognostic implications of DPGNEG. V-wave amplitude in the pulmonary artery wedge pressure (PAWP) curve was inversely associated with DPG at lower pulmonary vascular resistance (PVR), but not at higher levels. DPGNEG subjects showcased better prognosis as compared with positive, unelevated (< 7mmHg) DPG. In Study IV, mitral annular geometry was studied in 57 MS subjects undergoing PTMC employing 3D echocardiography. MS subjects demonstrated a more circular and flatter annulus, with significantly larger orthogonal diameters, annular circumference and area. Annular non-planarity and displacement demonstrated a tendency to normalize after PTMC. Baseline annular diameter demonstrated an association with post-procedural mitral regurgitation.In summary, AV coupling, DPGNEG and MA geometry assessment offers novel insights in MS.
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