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Cardiac Performance, Ventricular-Vascular Interaction and Functional Alterations in Rheumatic Mitral Stenosis: A descriptive study employing novel hemodynamic and echocardiographic modalities
KTH, School of Technology and Health (STH), Medical Engineering.
2016 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

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.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2016. , 16 p.
TRITA-STH : report, ISSN 1653-3836 ; 2016:6
National Category
Other Medical Engineering
Research subject
Applied Medical Technology
URN: urn:nbn:se:kth:diva-191253ISBN: 978-91-7729-078-0OAI: diva2:955730
Public defence
2016-09-19, T52, School of Technology and Health, Hälsovägen 11C, Huddinge, Sweden,, Stockholm, 09:00 (English)

QC 20160829

Available from: 2016-08-30 Created: 2016-08-26 Last updated: 2016-09-01Bibliographically approved
List of papers
1. The impact of arterial load on left ventricular performance: An invasive haemodynamic study in severe mitral stenosis
Open this publication in new window or tab >>The impact of arterial load on left ventricular performance: An invasive haemodynamic study in severe mitral stenosis
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2015 (English)In: Journal of Physiology, ISSN 0022-3751, E-ISSN 1469-7793, Vol. 593, no 8, 1901-1912 p.Article in journal (Refereed) Published
Abstract [en]

Key points: A hallmark of mitral stenosis (MS) is the markedly altered left ventricular (LV) loading. As most of the methods used to determine LV performance in MS patients are influenced by loading conditions, previous studies have shown conflicting results. The present study calculated LV elastance, which is a robust method to quantify LV function. We demonstrate that LV loading in MS patients is elevated but normalizes after valve repair and might be a result of reflex pathways. Additionally, we show that the LV in MS is less compliant than normal due to a combination of right ventricular loading and the valvular disease itself. Immediately after valve dilatation the increase in blood inflow into the LV results in even greater LV stiffness. Our findings enrich our understanding of heart function in MS patients and provide a simple reproducible way of assessing LV performance in MS. Left ventricular (LV) function in rheumatic mitral stenosis (MS) remains an issue of controversy, due to load dependency of previously employed assessment methods. We investigated LV performance in MS employing relatively load-independent indices robust to the altered loading state. We studied 106 subjects (32 ± 8 years, 72% female) with severe MS (0.8 ± 0.2 cm2) and 40 age-matched controls. MS subjects underwent simultaneous bi-ventricular catheterization and transthoracic echocardiography (TTE) before and immediately after percutaneous transvenous mitral commisurotomy (PTMC). Sphygmomanometric brachial artery pressures and TTE recordings were simultaneously acquired in controls. Single-beat LV elastance (E<inf>es</inf>) was employed for LV contractility measurements. Effective arterial elastance (E<inf>a</inf>) and LV diastolic stiffness were measured. MS patients demonstrated significantly elevated afterload (E<inf>a</inf>: 3.0 ± 1.3 vs. 1.5 ± 0.3 mmHg ml-1; P < 0.001) and LV contractility (E<inf>es</inf>: 4.1 ± 1.6 vs. 2.4 ± 0.5 mmHg ml-1; P < 0.001) as compared to controls, with higher E<inf>a</inf> in subjects with smaller mitral valve area (≤ 0.8 cm2) and pronounced subvalvular fusion. Stroke volume (49 ± 16 to 57 ± 17 ml; P < 0.001) and indexed LV end-diastolic volume (LVEDV<inf>index</inf>: 57 ± 16 to 64 ± 16 ml m-2; P < 0.001) increased following PTMC while E<inf>es</inf> and E<inf>a</inf> returned to more normal levels. Elevated LV stiffness was demonstrated at baseline and increased further following PTMC. Our findings provide evidence of elevated LV contractility, increased arterial load and increased diastolic stiffness in severe MS. Following PTMC, both LV contractility and afterload tend to normalize.

adult, arterial load, arterial pressure, artery compliance, Article, blood vessel parameters, brachial artery, cardiovascular parameters, controlled study, disease association, disease severity, female, heart afterload, heart catheterization, heart left ventricle compliance, heart left ventricle contractility, heart left ventricle diastolic stiffness, heart left ventricle ejection fraction, heart left ventricle enddiastolic volume, heart left ventricle failure, heart left ventricle function, heart preload, heart right ventricle enddiastolic volume, heart stroke volume, heart valve surgery, human, invasive procedure, major clinical study, male, mitral valve stenosis, percutaneous transvenous mitral commisurotomy, priority journal, sphygmomanometry, transthoracic echocardiography, treatment outcome
National Category
urn:nbn:se:kth:diva-167782 (URN)10.1113/jphysiol.2014.280404 (DOI)000353044300023 ()2-s2.0-84927692750 (ScopusID)

QC 20150526

Available from: 2015-05-26 Created: 2015-05-22 Last updated: 2016-08-29Bibliographically approved

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