7 research outputs found

    A 100-MESFET planar grid oscillator

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    Relationship among diastolic intraventricular pressure gradients, relaxation, and preload: impact of age and fitness.

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    Item does not contain fulltextDiastolic intraventricular pressure gradients (IVPGs) are a measure of the ability of the ventricle to facilitate its filling using diastolic suction. We assessed 15 healthy young but sedentary subjects, aged 65 yr with known reductions in ventricular compliance (elderly sedentary subjects; age, 70 +/- 4 yr); and 12 master athletes, aged >65 yr, previously shown to have preserved ventricular compliance (elderly fit subjects; age, 68 +/- 3 yr). Pulmonary capillary wedge pressure (PCWP) and echocardiography measurements were performed at baseline, during load manipulation by lower body negative pressure at -15 and -30 mmHg, and after saline infusion of 10 and 20 ml/kg (elderly) or 15 and 30 ml/kg (young). IVPGs were obtained from color M-mode Doppler echocardiograms. Baseline IVPGs were lower (1.2 +/- 0.4 vs. 2.4 +/- 0.7 mmHg, P < 0.0001), and the time constant of pressure decay (tau(0)) was longer (60 +/- 10 vs. 46 +/- 6 ms, P < 0.0001) in elderly sedentary than in young subjects, with no difference in PCWP. Although PCWP changes during load manipulations were similar (P = 0.70), IVPG changes were less prominent in elderly sedentary than in young subjects (P = 0.02). Changes in stroke volume and IVPGs during loading manipulations correlated (r = 0.96, P = 0.0002). PCWP and tau(0) were strong multivariate correlates of IVPGs (P < 0.001, for both). IVPG response to loading interventions in elderly sedentary and elderly fit subjects was similar (P = 0.33), despite known large differences in ventricular compliance. The ability to regulate IVPGs during changes in preload is impaired with aging. Preserving ventricular compliance during aging by lifelong exercise training does not prevent this impairment

    Opposing Wall Mechanics Are Significantly Influenced by Longitudinal Cardiac Rotation in the Assessment of Ventricular Dyssynchrony

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    ObjectivesThis study sought to assess whether longitudinal rotation (LR) affects myocardial systolic velocity profiles and to compare velocity-based measures of dyssynchrony with LR for predicting cardiac resynchronization therapy (CRT) response.BackgroundLongitudinal rotation, a rocking motion often seen when the dilated left ventricle (LV) is imaged in its horizontal long-axis plane, is a recently recognized phenomenon and a new predictor of response to CRT.MethodsOne hundred patients with CRT implants and suitable baseline echocardiograms were identified. Longitudinal rotation was assessed in the apical 4-chamber view by speckle-tracking techniques and myocardial systolic velocities for basal septum, and lateral LV were analyzed from tissue Doppler images. The quartiles of LR distribution were analyzed for differences in their systolic velocities. Correlation between measurements and reduction in LV end-systolic volume (ESV) at follow-up was performed.ResultsQuartile 1 had a mean LR of −6.8 ± 2.3°; quartile 4 showed a mean LR of 2.3 ± 1.6°. A depressed peak velocity of lateral wall, when compared with the septum, was found for quartile 1 (p = 0.01), whereas the converse was noted in quartile 4 (p = 0.0001). The difference in amplitude of peak velocity between septal and lateral walls was found to correlate with the pattern of LR and with percentage reduction in LV ESV at follow-up in nonischemic patients. Septal–lateral delay was not correlated with the presence of LR, nor was it predictive of reduction in LV ESV.ConclusionsPatients with prominent clockwise LR have depressed long-axis systolic velocities of the lateral wall, whereas the patients with counterclockwise LR have depressed septal wall velocities. The difference in peak amplitude of basal septal and lateral systolic velocities is predictive of LR, and in the nonischemic subgroup correlates with quantitative LV reverse remodeling at follow-up. Velocity time-based measures, including septal–lateral delay were not predictive of CRT response
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