Biomedical subjects

B I Munt

Publications and source records attributed to B I Munt.

4 recordsLinked to original sources

PubMed1998

Left ventricular shape analysis from three-dimensional echocardiograms.

The objective of this study was to develop and validate a three-dimensional technique of left ventricular shape analysis. Geometric phantoms and left ventricles of excised calf hearts, normal human subjects, and one subject each with aortic stenosis and dilated cardiomyopathy were reconstructed from three-dimensional echocardiograms. The fit between the reconstructions and true surfaces of the geometric phantoms and excised ventricles was determined. To evaluate in vivo left ventricular shape, a center axis was constructed from the centroid of the mitral annulus to the furthest endocardial point. Regional shape was evaluated as the relative distances of 16 separate myocardial segments from the center axis compared with a population-derived mean value. Global shape was evaluated as the average standard deviation from the normal value over the 16 segments. The system precisely reproduced the shapes of the phantoms and excised left ventricles (root-mean-square error between true and reconstructed surface 1.0 0.2 mm and 1.2 0.8 mm, respectively). The in vivo shape analysis differentiated the pathological from normal left ventricles.

Adult↗

PubMed1998

Three-dimensional measurement of the mitral annulus by multiplane transesophageal echocardiography: in vitro validation and in vivo demonstration.

Ten phantoms were scanned with a multiplane transesophageal echocardiographic probe in a water bath to assess a new method for three-dimensional modeling of the mitral annulus. The annulus was reconstructed from manually outlined borders with Fourier series in each of the three spatial coordinates. Comparisons with direct measurements by least-squares linear regression gave coefficients of determination of 0.99 for annular height, area, and circumference. Expressed as a percentage of their true values, the mean +/- SD of the errors were -0.1% +/- 3.0% for annular height, -2.8% +/- 3.1% for area, and -0.2% +/- 1.7% for circumference. The mean residual error length for phantoms was 0.64 mm compared with 1.21 mm in nine patients studied during general anesthesia. This method gives accurate and precise measurements of the mitral annulus in vitro and should be valuable for studying its morphology and dynamics in vivo.

Adult↗

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↗