Biomedical subjects

N L Healy

Publications and source records attributed to N L Healy.

5 recordsLinked to original sources

PubMed1997

Prospective study of asymptomatic valvular aortic stenosis. Clinical, echocardiographic, and exercise predictors of outcome.

BACKGROUND: Only limited data on the rate of hemodynamic progression and predictors of outcome in asymptomatic patients with valvular aortic stenosis (AS) are available. METHODS AND RESULTS: In 123 adults (mean age, 63 +/- 16 years) with asymptomatic AS, annual clinical, echocardiographic, and exercise data were obtained prospectively (mean follow-up of 2.5 +/- 1.4 years). Aortic jet velocity increased by 0.32 +/- 0.34 m/s per year and mean gradient by 7 +/- 7 mm Hg per year; valve area decreased by 0.12 +/- 0.19 cm2 per year. Kaplan-Meier event-free survival, with end points defined as death (n = 8) or aortic valve surgery (n = 48), was 93 +/- 5% at 1 year, 62 +/- 8% at 3 years, and 26 +/- 10% at 5 years. Univariate predictors of outcome included baseline jet velocity, mean gradient, valve area, and the rate of increase in jet velocity (all P < or = .001) but not age, sex, or cause of AS. Those with an end point had a smaller exercise increase in valve area, blood pressure, and cardiac output and a greater exercise decrease in stroke volume. Multivariate predictors of outcome were jet velocity at baseline (P < .0001), the rate of change in jet velocity (P < .0001), and functional status score (P = .002). The likelihood of remaining alive without valve replacement at 2 years was only 21 +/- 18% for a jet velocity at entry > 4.0 m/s, compared with 66 +/- 13% for a velocity of 3.0 to 4.0 m/s and 84 +/- 16% for a jet velocity < 3.0 m/s (P < .0001). CONCLUSIONS: In adults with asymptomatic AS, the rate of hemodynamic progression and clinical outcome are predicted by jet velocity, the rate of change in jet velocity, and functional status.

Aged↗

PubMed1997

Effects of aortic valve replacement on exercise duration and functional status in adults with valvular aortic stenosis.

OBJECTIVE: To evaluate the effect of aortic valve replacement on left ventricular function, functional status and exercise duration in an adult population with valvular aortic stenosis. DESIGN: Prospective study of initially asymptomatic patients with pre- and postvalve replacement echocardiography, functional status score and exercise data. SETTING: University-affiliated, tertiary care teaching hospital. PATIENTS: Valvular aortic stenosis patients referred from academic and private practice internists and cardiologists (n = 34, 65% men, mean age 68 +/- 11 years, preoperative aortic valve area 0.9 +/- 0.4 cm2). INTERVENTIONS: Annual Doppler echocardiography, functional status questionnaires and, if possible, Bruce protocol maximal exercise tolerance tests. MAIN RESULTS: Aortic valve replacement resulted in a decrease in maximum jet velocity (pre 4.7 +/- 0.7 versus post 2.9 +/- 0.7 m/s, P = 0.0001) and left ventricular mass (pre 167 +/- 37 versus post 134 +/- 32 g, P = 0.0001) and an increase in left ventricular ejection fraction (pre 65 +/- 11 versus post 69 +/- 10%, P = 0.05) at rest. However, there was no change in the ratio of early to atrial diastolic filling velocities (pre 1.2 +/- 0.5 versus post 1.4 +/- 0.8, not significant), exercise tolerance as assessed by estimated functional aerobic impairment (pre 26 +/- 32 versus post 22 +/- 27%, not significant) or functional status score (pre 89 +/- 13 versus post 91 +/- 11, not significant). CONCLUSIONS: When the aortic valve is replaced promptly at symptom onset, despite improvement in resting left ventricular systolic performance, there is no evidence of improvement in exercise capacity or functional status.

Aged↗

PubMed1996

Gender differences in left ventricular function at rest and with exercise in asymptomatic aortic stenosis.

In 29 women and 53 men with asymptomatic aortic stenosis, two-dimensional (2-D) and Doppler echocardiography were performed at rest and immediately after treadmill exercise testing to examine gender differences in left ventricular geometry, systolic and diastolic function, functional status, and exercise capacity. Aortic stenosis severity was similar between men and women. Women reported more functional impairment than men (88% +/- 14% vs 95% +/- 7%; p = 0.02). When indexed to body surface area, women had a smaller end-diastolic volume (39 +/- 14 vs 50 +/- 15 ml/m2; p = 0.002), end-systolic volume (13 +/- 6 ml/m2 vs 18 +/- 9 ml/m2; p = 0.01) and left ventricular mass (73 +/- 26 gm/m2 vs 84 +/- 21 gm/m2; p = 0.05), but a higher relative wall thickness in systole (1.5 +/- 0.4 cm vs 1.3 +/- 0.4 cm; p = 0.05), and fractional shortening (43% +/- 7% vs 39% +/- 10%; p = 0.03). Women had higher early and late transmitral velocities than did men (early, 92 +/- 24 cm/sec vs 79 +/- 29 cm/sec; p = 0.05; late, 97 +/- 30 cm/sec vs 68 +/- 23 cm/sec; p < 0.0001), a higher time-velocity integral in early diastole (18.2 +/- 4.8 cm vs 15.1 +/- 4.3 cm; p = 0.006), a significantly shorter exercise duration (4.5 +/- 4.1 minutes vs 8.0 +/- 3.9 minutes; p < 0.0001), a greater degree of functional aerobic impairment (25% +/- 48% vs 2% +/- 33%; p = 0.02), and a smaller increase in cardiac output with exercise (5.4 +/- 3.5 L/min vs 8.0 +/- 4.3 L/min; p = 0.01), in spite of similar peak heart rate and blood pressure responses. In these asymptomatic subjects with aortic stenosis, women had smaller, relatively hypercontractile ventricles, a different diastolic filling profile, more exercise limitation, and poorer functional capacity. These findings demonstrate the importance of gender in the response of the left ventricle to chronic pressure overload.

Adult↗

PubMed1994

Flow dependence of measures of aortic stenosis severity during exercise.

OBJECTIVES: This study was designed to investigate the effect of altering transvalvular volume flow rate on indexes of aortic stenosis severity (valve area, valve resistance, percent left ventricular stroke work loss) derived by using Doppler echocardiography. BACKGROUND: Assessment of hemodynamic severity in aortic stenosis has been limited by the absence of an index that is independent of transvalvular flow rate. The traditional measurement of valve area by the Gorlin equation has been shown to vary with alterations in transvalvular flow. Recently, valve resistance and percent stroke work loss have been proposed as indexes that are relatively independent of flow. Although typically derived with invasive measurements, valve resistance and percent stroke work loss (in addition to continuity equation valve area) can be determined noninvasively with Doppler echocardiography. METHODS: We performed 110 symptom-limited exercise studies in 66 asymptomatic patients with valvular aortic stenosis. Continuity equation valve area, valve resistance (the ratio between mean transvalvular pressure gradient and mean flow rate) and the steady component of percent stroke work loss (the ratio between mean transvalvular pressure gradient and left ventricular systolic pressure) were assessed by Doppler echocardiography at rest and immediately after exercise. RESULTS: Mean transvalvular volume flow rate increased 24% (from [mean +/- SD] 319 +/- 80 to 400 +/- 140 ml/s, p < 0.0001); mean pressure gradient increased 36% (from 30 +/- 14 to 41 +/- 18 mm Hg, p < 0.0001); continuity equation aortic valve area increased 14% (from 1.38 +/- 0.50 to 1.58 +/- 0.69 cm2, p < 0.0001); valve resistance increased 13% (from 137 +/- 81 to 155 +/- 97 dynes.s.cm-5, p < 0.0001); and percent stroke work loss increased 17% (from 17.4 +/- 6.9% to 20.3 +/- 8.5%, p < 0.0001). The effects of flow on valve area, valve resistance and percent stroke work loss were independent of the presence of an aortic valve area < or = or > 1.0 cm2 or reduced transvalvular flow rate (rest cardiac output < 4.5 liters/min). CONCLUSIONS: In patients with asymptomatic aortic stenosis, Doppler echocardiographic measures of valve area, valve resistance and percent stroke work loss are flow dependent. Flow dependence is observed with valve area < or = or > 1.0 cm2 and in the presence of both normal and low transvalvular flow states. The potential effects of transvalvular flow should be considered when interpreting Doppler measures of aortic stenosis severity.

Adult↗

PubMed1992

Elbow flexion contractures treated with serial casts and conservative therapy.

We report on the technique of serial casts to successfully reverse elbow flexion contractures in three patients. Patients considered for this technique had a traumatic injury to the elbow that resulted in residual soft tissue restrictions; their mean flexion deformity was 44 degrees, which had been present for an average of 6 months. Treatment consisted of traditional therapy methods to obtain initial stretch and elongation of tissue followed by application of a cylindrical fiberglass cast in the position of maximal elbow extension. The cast was worn for 3 to 5 days, then removed, and the entire process was repeated. After the use of serial casts, elbow flexion contractures were reduced to a mean of 11 degrees. These results have been maintained over an average of 26 months. The use of casts in the treatment of elbow flexion contractures appears to be a viable technique for increasing range of motion when traditional methods of treatment alone are unsuccessful and surgical intervention may be the only alternative.

Adolescent↗