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Julius M. Gardin

Publications and source records attributed to Julius M. Gardin.

7 recordsLinked to original sources
PubMed2000

Orthostatic Hypotension in the Elderly: Contributions of Impaired LV Filling and Altered Sympathovagal Balance.

Orthostatic hypotension, which occurs in 5%-18% of the elderly, may contribute to age-related disability. While autonomic dysfunction and alterations of cardiac structure and function likely to impair postural maintenance of blood pressure are common in the elderly, these have not been jointly studied in large cohorts. The authors evaluated the association of orthostatic hypotension with echocardiographic measures of cardiac structure and function, and with autonomic function determined by analysis of heart rate variability, in a large population of community-dwelling elderly. A total of 5201 men and women, aged 65-100 years and living in four geographically separate communities, were recruited from Medicare eligibility lists. In this prospective, observational cohort study, measurements included clinical questionnaires, standing and supine blood pressures, mini-glucose tolerance testing, echocardiography, and 24-hour Holter recording for assessment of heart rate variability. Orthostatic hypotension, defined as a decrease in standing systolic blood pressure of 20 mm Hg or more, was positively associated in bivariate analyses with left ventricular wall thickness, peak velocity of late diastolic filling, vagal tone on heart rate variability analysis, supine systolic pressure, supine diastolic pressure, age, and diabetes, and inversely associated with body weight. After statistical adjustment for the presence of myocardial infarction, stroke, and use of antihypertensive medication, the associations were maintained, and a previous trend toward an association with decreased left ventricular cavity size became statistically significant. The data suggest that in elderly, community-based individuals, orthostatic hypotension is associated with increased blood pressure and decreased weight; it possibly acts mechanistically via altered sympathovagal balance, increased left ventricular wall thickness, decreased left ventricular preload, and alterations of left ventricular diastolic filling. (c) 2000 by CVRR, Inc.

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PubMed1999

Reproducibility of Brachial Artery Ultrasound Measurements.

Recent findings suggest that systemic artery endothelial function is associated with the preclinical phase of vascular disease and related to traditional atherosclerosis risk factors. Brachial artery diameter changes in response to hyperemia have been proposed recently as a noninvasive tool to assess endothelial function. To evaluate the reproducibility of brachial artery diameter measurements using ultrasound, we studied 12 healthy subjects (eight men and four women, mean age 37 +/- 9 years). An ATL HDI 3000 machine with a 5- to 10-MHz broadband transducer was used to image the right brachial artery at rest, approximately 4 cm above the elbow. Gray scale ultrasound and color Doppler long-axis images were recorded. Brachial arterial outer diameter (i.e., from anterior adventitia to posterior adventitia) and inner diameter (i.e., from anterior lumen-intima interface to posterior lumen-intima interface) were measured in each subject by two observers. An offline analysis system was used to make measurements at end-diastole from four cardiac cycles. Interobserver and intraobserver measurement variabilities (technical error rates) for brachial artery inner diameter were excellent, ranging from 2.5% to 3.8%. However, interobserver technical error rates for outer diameter measurements were significantly greater than those for inner diameter measurements, ranging from 16.3% to 22.1% (P < 0.001), presumably related to the difficulty in accurately defining the adventitial lines. There were no significant differences in interobserver and intraobserver variability for measurements made using gray scale and color Doppler-aided techniques. We conclude that interobserver and intraobserver reproducibility for brachial artery inner diameter measurements made from ultrasound images is excellent.

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PubMed1996

Intravascular Ultrasound Catheter Evaluation of the Left Ventricle in Mice: A Feasibility Study.

With the advent of transgenic technology, it has become increasingly important to find a method for evaluating left ventricular (LV) anatomy and function in intact wild type, intervened, and transgenic mice. Mice are 1/10th the size of rats, and have body masses of 10-60 g, LV masses of 40-150 mg, LV wall thicknesses of 0.5-2 mm, and LV internal dimensions of 1-3 mm. Although the murine LV has been imaged by transthoracic (TTE) two-dimensional directed M-mode echocardiography, we explored the use of intravascular ultrasound (IVUS) catheters, with imaging from various positions, to see if better two-dimensional images of the LV could be obtained by IVUS than TTE. Eight normal mice were anesthetized using pentobarbital or avertin. The mice were studied using a commercially available IVUS system (Endosonics, Inc.). Two IVUS catheters (3.5 and 5.0 Fr) with 20-MHz multielement array transducers were used. Each catheter had a 4.0-mm imaging depth of field in all directions (360 degrees ) from the mid-point of the catheter core. Multiple imaging approaches were attempted: transesophageal (TEE); transjugular (TJ); transperitoneal (TP); and open chest, from both epicardial surface (Ep) and via direct LV puncture. TEE and TJ approaches afforded insufficient depth of field to image the entire LV in cross section. TP and Ep approaches resulted in poor images, related both to inadequate depth of field and to relatively small sector angles subtended by imaging elements. LVP (intracavitary imaging) was capable of satisfactorily imaging the LV epicardium, but was unable to image the endocardium, probably because the latter was within the 1.9-mm "ringdown" catheter artifact. All IVUS approach studies lacked sufficient temporal resolution (10 frames/sec) to reliably display systolic and diastolic frames necessary for evaluation of LV function. In contrast, as previously reported, transthoracic two-dimensionally directed M-mode echocardiograms have sufficient temporal and spatial resolution to permit accurate estimates of LV mass and systolic function. Currently, IVUS catheter-based approaches are not feasible for imaging murine LV anatomy and function. Limitations include: (1) inadequate temporal resolution might be improved by ECG gating; (2) limited depth of field possibly resolvable by lower frequency transducers; and (3) relatively large catheter size. (ECHOCARDIOGRAPHY, Volume 13, November 1996)

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