Investigating the three-dimensional flow separation induced by a model vocal fold polyp.

The fluid-structure energy exchange process for normal speech has been studied extensively, but it is not well understood for pathological conditions. Polyps and nodules, which are geometric abnormalities that form on the medial surface of the vocal folds, can disrupt vocal fold dynamics and thus can have devastating consequences on a patient's ability to communicate. Our laboratory has reported particle image velocimetry (PIV) measurements, within an investigation of a model polyp located on the medial surface of an in vitro driven vocal fold model, which show that such a geometric abnormality considerably disrupts the glottal jet behavior.

Response to "Comments on 'A theoretical model of the pressure distributions arising from asymmetric intraglottal flows applied to a two-mass model of the vocal folds'" [J. Acoust. Soc. Am. 130, 389-403 (2011)].

Hirschberg [J. Acoust. Soc.

Loss of adrenergic augmentation of diastolic intra-LV pressure difference in patients with diastolic dysfunction: evaluation by color M-mode echocardiography.

Objectives: The aim of this study was to evaluate the hypothesis that the adrenergic response of the intraventricular pressure difference (IVPD) is reduced in patients with preserved ejection fraction (EF) and diastolic dysfunction (DD).

Background: In early diastole, there is a progressive IVPD extending from the left atrium (LA) to the left ventricular (LV) apex. In response to adrenergic stimulation, as occurs during exercise, the IVPD increases allowing rapid filling without an abnormal increase in LA pressure.

Left ventricular vortex formation is unaffected by diastolic impairment.

Normal left ventricular (LV) filling occurs rapidly early in diastole caused by a progressive pressure gradient within the ventricle and with a low left atrial pressure. This normal diastolic function is altered in patients with heart failure. Such impairment of diastolic filling is manifested as an abrupt deceleration of the early filling wave velocity.

Assessment of left ventricular diastolic function using 4-dimensional phase-contrast cardiac magnetic resonance.

Objectives: Phase-contrast magnetic resonance imaging can potentially assess the dynamics of left ventricular (LV) early diastolic filling.

Methods: Fifteen participants underwent phase-contrast magnetic resonance imaging on a 1.5-T whole-body Avanto scanner (Siemens Healthcare, Erlangen, Germany).

Evaluation of LV diastolic function from color M-mode echocardiography.

Objectives: this study evaluated early diastolic filling dynamics using a semiautomated objective analysis of filling velocities obtained from color M-mode echocardiography.

Background: diastolic function can be evaluated from color M-mode echocardiography by measuring the early diastolic flow propagation velocity (Vp) from the slope of a single linear approximation of an isovelocity contour. However, this method has limitations and may not accurately represent diastolic filling.