The clinical effects of a cardioselective beta-adrenergic blocking drug, acebutolol, were studied in 25 patients with chronic stable angina, using a seven-week single-blind placebo leads to acebutolol (mean dose 913 mg/day) phase followed by 12-week randomized double-blind placebo leads to acebutolol (mean dose 968 mg/day) crossover protocol. Objective parameters from exercise treadmill tests showed consistent reduction in resting and maximal exercise heart rate and rate-pressure product during both single- and double-blind phases. Duration of exercise and maximal ST segment depression were not significantly altered. Subjective improvement following acebutolol was observed with reduced frequency of anginal attacks and nitroglycerin consumption during the single-blind phase. However, no differences were seen during the double-blind phase due to significant subjective improvement during the latter placebo period. Adverse effects observed were mild in nature and were similar to those seen with other beta blockers. These data establish acebutolol as a potent beta-blocking agent and emphasize the importance of utilizing objective parameters over subjective variables in demonstrating the clinical antianginal efficacy of a beta blocker.

Acebutolol↗

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Quantification of mitral regurgitant volume by the color Doppler proximal isovelocity surface area method: a clinical study.

In vitro studies have demonstrated that regurgitant flow rate can be estimated by the color Doppler "proximal isovelocity surface area" (PISA) method. By applying the PISA method and continuity principle, we developed a formula to calculate mitral regurgitant volume: 2 pi r2.VN.FVI/Vo, where r = distance from the first jet alias to mitral leaflets, VN = aliasing velocity, FVI = flow velocity integral or regurgitant jet, and Vo = peak velocity through the regurgitant orifice. Doppler echocardiography was performed in 20 patients with mitral regurgitation. The mitral regurgitant volume was estimated by PISA and compared to cine ventriculographic grading. The results showed an increase in regurgitant volume by PISA compared with increasing angiographic grades of mitral regurgitation: 19 +/- 0.6, 18 +/- 5, 25 +/- 12, and 44 +/- 4 ml for grades 1+ to 4+, respectively (r = 0.77). Thus a formula developed from PISA is able to identify patients with a severe grade of mitral regurgitation and to provide an alternate approach to the noninvasive quantitation of mitral regurgitation.

Adult↗

PubMedDate not supplied

Ultrasound beam orientation during standard two-dimensional imaging: assessment by three-dimensional echocardiography.

Standard two-dimensional echocardiographic image planes are defined by anatomic landmarks and assumptions regarding their orientation when these landmarks are visualized. However, variations of anatomy and technique may invalidate these assumptions and thus limit reproducibility and accuracy of cardiac dimensions recorded from these views. To overcome this problem, we have developed a three-dimensional echocardiograph consisting of a real-time scanner, three-dimensional spatial locater, and personal computer. This system displays the line of intersection of a real-time image and an orthogonal reference image and may be used to assess actual image orientation during standardized two-dimensional imaging when the line-of-intersection display is not observed by the operator. Three hundred forty standard images were assessed from 85 examinations by 11 echocardiographers. Twenty-four percent of the unguided standard images were optimally positioned within +/- 5 mm and +/- 15 degrees of the standard. Of the optimal images, two thirds were parasternal long-axis views. A subsequent study with three-dimensional echocardiography and line-of-intersection guidance of image positioning showed 80% of the guided images to be optimally positioned, a threefold improvement (p < 0.001). Two-dimensional echocardiography does not achieve reasonably consistent optimal positioning of standard imaging views, suggesting that measurements taken from these views are likely to be suboptimal. Three-dimensional echocardiography that uses line-of-intersection guidance improves image positioning threefold and should therefore improve the accuracy and reproducibility of quantitative echocardiographic measurements derived from these images.

Adolescent↗

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Three-dimensional echocardiographic volume computation: in vitro comparison to standard two-dimensional echocardiography.

Two-dimensional (2D) echocardiographic methods for quantitative left ventricular volume computation have been shown to have a low predictive accuracy and reproducibility. To address the problem of geometric assumptions and image plane positioning errors inherent in 2D echocardiography, three-dimensional (3D) echocardiographic systems have been constructed that provide spatial registration and display of transducer-image position and orientation. Although 3D echocardiography has been shown to accurately measure volume in vitro and in vivo, only preliminary data exist demonstrating its superiority over standard 2D echocardiography. We calculated the volume of 30 water-filled latex balloon phantoms of varying size (40 to 200 ml) and shape using each method. Fifteen phantoms were nondistorted (ellipsoid or pear shaped); 15 were symmetrically distorted (dumbbell shaped). Although both 2D and 3D echocardiography showed an excellent correlation to the true volume (r = 0.97 and 0.99, respectively), the standard error of the estimate for 2D echocardiography was twofold larger than for 3D echocardiography (SEE = 6.7 ml and 3.52 ml, respectively). The true volume was slightly underestimated by 3D echocardiography (-2.83 ml), whereas 2D echocardiography overestimated a similar amount (+2.87 ml). The accuracy and variability for 2D echocardiography were significantly poorer (5.22% +/- 5.66% and 5.29% +/- 5.6%, p = 0.001 and 0.002, respectively) as compared with 3D echocardiography (3.7% +/- 2.65% and 2.65% +/- 1.9%, respectively). We conclude that 3D echocardiography with guided image plane positioning and a novel algorithm for volume computation (polyhedral surface reconstruction) achieves significantly more accurate and reproducible results than conventional 2D echocardiography with the modified Simpson's rule.(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiac Volume↗

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