Role of Mitral Annulus Diastolic Geometry on Intraventricular Filling Dynamics

The mitral valve (MV) is a bileaflet valve positioned between the left atrium and ventricle of the heart. The annulus of the MV has been observed to undergo geometric changes during the cardiac cycle, transforming from a saddle D-shape during systole to a flat (and less eccentric) D-shape during diastole. Prosthetic MV devices, including heart valves and annuloplasty rings, are designed based on these two configurations, with the circular design of some prosthetic heart valves (PHVs) being an approximation of the less eccentric, flat D-shape. Characterizing the effects of these geometrical variations on the filling efficiency of the left ventricle (LV) is required to understand why the flat D-shaped annulus is observed in the native MV during diastole in addition to optimizing the design of prosthetic devices. We hypothesize that the D-shaped annulus reduces energy loss during ventricular filling. An experimental left heart simulator (LHS) consisting of a flexible-walled LV physical model was used to characterize the filling efficiency of the two mitral annular geometries. The strength of the dominant vortical structure formed and the energy dissipation rate (EDR) of the measured fields, during the diastolic period of the cardiac cycle, were used as metrics to quantify the filling efficiency. Our results indicated that the O-shaped annulus generates a stronger (25% relative to the D-shaped annulus) vortical structure than that of the D-shaped annulus. It was also found that the O-shaped annulus resulted in higher EDR values throughout the diastolic period of the cardiac cycle. The results support the hypothesis that a D-shaped mitral annulus reduces dissipative energy losses in ventricular filling during diastole and in turn suggests that a symmetric stent design does not provide lower filling efficiency than an equivalent asymmetric design.

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Left ventricular endocardial longitudinal and transverse changes during isovolumic contraction and relaxation: a challenge

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.00867.2004 ◽

2005 ◽

Vol 289 (1) ◽

pp. H196-H201 ◽

Cited By ~ 38

Author(s):

Wolfgang A. Goetz ◽

Emmanuel Lansac ◽

Hou-Sen Lim ◽

Patricia A. Weber ◽

Carlos M. G. Duran

Keyword(s):

Mitral Valve ◽

Cardiac Cycle ◽

Mitral Annulus ◽

Left Ventricular ◽

Transverse Diameter ◽

Isovolumic Contraction ◽

Valve Opening ◽

Contraction And Relaxation ◽

Geometric Changes ◽

Longitudinal Diameter

Left ventricular (LV) longitudinal and transverse geometric changes during isovolumic contraction and relaxation are still controversial. This confusion is compounded by traditional definitions of these phases of the cardiac cycle. High-resolution sonomicrometry studies might clarify these issues. Crystals were implanted in six sheep at the LV apex, fibrous trigones, lateral and posterior mitral annulus, base of the aortic right coronary sinus, anterior and septal endocardial wall, papillary muscle tips, and edge of the anterior and posterior mitral leaflets. Changes in distances were time related to LV and aortic pressures and to mitral valve opening. At the beginning of isovolumic contraction, while the mitral valve was still open, the LV endocardial transverse diameter started to shorten while the endocardial longitudinal diameter increased. During isovolumic relaxation, while the mitral valve was closed, LV transverse diameter started to increase while the longitudinal diameter continued to decrease. These findings are inconsistent with the classic definitions of the phases of the cardiac cycle.

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Anticoagulation for Cardiac Prosthetic Devices: Prosthetic Heart Valves, Left Ventricular Assist Devices, and Septal Closure Devices

Anticoagulation Therapy ◽

10.1007/978-3-319-73709-6_13 ◽

2018 ◽

pp. 253-295

Author(s):

Matthew T. Crim ◽

Supriya Shore ◽

Suegene K. Lee ◽

Bryan J. Wells

Keyword(s):

Heart Valves ◽

Left Ventricular ◽

Ventricular Assist Devices ◽

Prosthetic Heart Valves ◽

Left Ventricular Assist Devices ◽

Ventricular Assist ◽

Prosthetic Devices ◽

Assist Devices ◽

Left Ventricular Assist

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Infections Associated with Prosthetic Devices: Clinical Considerations

The International Journal of Artificial Organs ◽

10.1177/039139889301601102 ◽

1993 ◽

Vol 16 (11) ◽

pp. 749-754 ◽

Cited By ~ 15

Author(s):

G.M. Dickinson ◽

A.L. Bisno

Keyword(s):

Heart Valves ◽

Contact Lenses ◽

Diagnostic Methods ◽

Prosthetic Heart Valves ◽

Prosthetic Devices ◽

Synthetic Materials ◽

Appropriate Therapy ◽

Clinical Considerations ◽

Medicine Today ◽

Device Associated Infection

The successful development of synthetic materials and introduction of artificial devices into nearly all body systems has been shadowed by the adaptation of microorganisms to the opportunities these devices afford for eluding defenses and invading the host. Clinicians are faced with the task of recognizing the manifestations of device-associated infection, predicting the likely pathogens involved, knowing the appropriate diagnostic methods, and initiating appropriate therapy. Infections associated with prosthetic heart valves are particularly challenging to successfully treat; surgical replacement may be necessary. Infection associated with an artificial joint usually requires removal of the device in addition to appropriate antibiotics. Intravascular associated infections are the leading cause of nosocomial bacteremias and, because of their intravascular location, these infections are often life catheter threatening if not promptly diagnosed and treated. Even contact lenses, external to epithelial surfaces, may give rise to serious sight-threatening infections. Although artificial devices play a paramount role in medicine today, infection is an ever present potential with which clinicians must be familiar.

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Analysis of the Genotype and Virulence of Staphylococcus epidermidis Isolates from Patients with Infective Endocarditis

Infection and Immunity ◽

10.1128/iai.00606-08 ◽

2008 ◽

Vol 76 (11) ◽

pp. 5127-5132 ◽

Cited By ~ 25

Author(s):

Alastair B. Monk ◽

Sam Boundy ◽

Vivian H. Chu ◽

Jill C. Bettinger ◽

Jaime R. Robles ◽

...

Keyword(s):

Staphylococcus Epidermidis ◽

Heart Valves ◽

Prosthetic Valve Endocarditis ◽

Bloodstream Infections ◽

Prosthetic Heart Valves ◽

Native Valve ◽

Prosthetic Devices ◽

C Elegans ◽

Prosthetic Valves ◽

Kaplan Meier

ABSTRACT Staphylococcus epidermidis is one of the most common causes of infections of prosthetic heart valves (prosthetic valve endocarditis [PVE]) and an increasingly common cause of infections of native heart valves (native valve endocarditis [NVE]). While S. epidermidis typically causes indolent infections of prosthetic devices, including prosthetic valves and intravascular catheters, S. epidermidis NVE is a virulent infection associated with valve destruction and high mortality. In order to see if the differences in the course of infection were due to characteristics of the infecting organisms, we examined 31 S. epidermidis NVE and 65 PVE isolates, as well as 21 isolates from blood cultures (representing bloodstream infections [BSI]) and 28 isolates from nasal specimens or cultures considered to indicate skin carriage. Multilocus sequence typing showed both NVE and PVE isolates to have more unique sequence types (types not shared by the other groups; 74 and 71%, respectively) than either BSI isolates (10%) or skin isolates (42%). Thirty NVE, 16 PVE, and a total of 9 of the nasal, skin, and BSI isolates were tested for virulence in Caenorhabditis elegans. Twenty-one (70%) of the 30 NVE isolates killed at least 50% of the worms by day 5, compared to 1 (6%) of 16 PVE isolates and 1 (11%) of 9 nasal, skin, or BSI isolates. In addition, the C. elegans survival rate as assessed by log rank analyses of Kaplan-Meier survival curves was significantly lower for NVE isolates than for each other group of isolates (P < 0.0001). There was no correlation between the production of poly-β(1-6)-N-acetylglucosamine exopolysaccharide and virulence in worms. This study is the first analysis suggesting that S. epidermidis isolates from patients with NVE constitute a more virulent subset within this species.

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Study of the Velocity and Strain Fields in the Flow Through Prosthetic Heart Valves

Journal of Biomechanical Engineering ◽

10.1115/1.4005475 ◽

2011 ◽

Vol 133 (12) ◽

Cited By ~ 4

Author(s):

A. López-Zazueta ◽

R. Ledesma-Alonso ◽

J. E. V. Guzman ◽

R. Zenit

Keyword(s):

Heart Valves ◽

Cardiac Cycle ◽

Strain Tensor ◽

Stereoscopic Particle Image Velocimetry ◽

Prosthetic Heart Valves ◽

Blood Constituents ◽

Future Design ◽

Spatial And Temporal Distributions ◽

Image Velocimetry ◽

Damage Process

A comparative experimental study of the velocity field and the strain field produced down-stream of biological and mechanical artificial valves is presented. In order to determine the spatial and temporal distributions of these fields, a phase-locked stereoscopic particle image velocimetry (or 3D-PIV) technique was implemented. Emphasis was placed on the identification of the fundamental differences between the extensional and the shear components of the strain tensor. The analysis of the characteristic flows reveal that the strains in every direction may reach high values at different times during the cardiac cycle. It was found that elevated strain levels persist throughout the cardiac cycle as a result of all these contributions. Finally, it is suggested that the frequency with which the strain variations occur at particular instants and locations could be associated to the cumulative damage process of the blood constituents and should be taken into account in the overall assessment of existing valve types, as well as in future design efforts.

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374 Ventricular filling mechanisms: study of regional pressure gradients and myocardial segmental lengths along the cardiac cycle

European Journal of Heart Failure Supplements ◽

10.1016/s1567-4215(06)80236-5 ◽

2006 ◽

Vol 5 (1) ◽

pp. 83-83

Author(s):

M GUERRA ◽

M AMORIM ◽

C BRASSILVA ◽

A LEITEMOREIRA

Keyword(s):

Cardiac Cycle ◽

Pressure Gradients ◽

Ventricular Filling

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The Effect of Dipyridamole and RA 233 on Human Platelet Function in Vitro

Thrombosis and Haemostasis ◽

10.1055/s-0038-1648112 ◽

1973 ◽

Vol 29 (03) ◽

pp. 694-700 ◽

Cited By ~ 4

Author(s):

Paul L. Rifkin ◽

Marjorie B. Zucker

Keyword(s):

Mechanism Of Action ◽

Human Blood ◽

Glass Bead ◽

Heart Valves ◽

Human Platelet ◽

Drug Effects ◽

Simple Relation ◽

Prosthetic Heart Valves ◽

Induced Aggregation

SummaryDipyridamole (Persantin) is reported to prolong platelet survival and inhibit embolism in patients with prosthetic heart valves, but its mechanism of action is unknown. Fifty jxM dipyridamole failed to reduce the high percentage of platelets retained when heparinized human blood was passed through a glass bead column, but prolonged the inhibition of retention caused by disturbing blood in vitro. Possibly the prostheses act like disturbance. Although RA 233 was as effective as dipyridamole in inhibiting the return of retention, it was less effective in preventing the uptake of adenosine into erythrocytes, and more active in inhibiting ADP-induced aggregation and release. Thus there is no simple relation between these drug effects.

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