A semiautomated objective technique for applying the proximal isovelocity surface area method to quantitate mitral regurgitation: Clinical studies with the digital flow map.

BACKGROUND: Clinical application of the color Doppler proximal isovelocity surface area (PISA) method to quantify mitral regurgitation (MR) has been limited by the often inaccurate assumption that isovelocity surfaces are hemispheric. This study applied an objective method for selecting the region where the hemispheric geometry holds best on the basis of mathematic analysis of results at different distances from the orifice. We aimed to demonstrate this approach can be applied accurately in the clinical setting and can be semiautomated to promote routine use by extracting velocities from the digital Doppler output and then performing all the calculations automatically. METHODS: In 75 patients with isolated MR, centerline velocities (V(r)) at each distance (r) from the orifice in the proximal flow field were extracted digitally. The automated analysis calculated peak MR flow rates as 2pir(2)V(r) and plotted these against their respective velocities. The optimal value for peak flow rate was obtained mathematically at the site where the slope of this curve was minimal (least inaccuracy). This value was combined with continuous wave Doppler data to provide regurgitant stroke volume (RSV) and orifice area (ROA), which were compared with quantitative Doppler in 75 patients and angiography in 42. RESULTS: RSV and ROA by this optimized, semiautomated PISA method correlated and agreed well with values from quantitative Doppler (y = 0.9x + 1.9, r = 0.90, standard error of the estimate [SEE] = 8.1 mL, mean difference = -0.7 +/- 8.5 mL for RSV; y = 0.9x + 0.02, r = 0.90, SEE = 0.048 cm(2), mean difference = -0.005 +/- 0.1 cm(2) for ROA) and correlated well with angiography (rho = 0.90 for both RSV and ROA). CONCLUSIONS: This objective PISA method for quantifying MR is accurate in the clinical setting and has been semiautomated by use of analysis of digital velocity data to provide a rapid and practical technique suitable to facilitate more extensive application in routine practice.

Anatomic M-mode: a new technique for quantitative assessment of left ventricular size and function.

To overcome the limitations of conventional M-mode echocardiography, a new technique referred to as anatomic M-mode has been recently developed. This technique is based on postprocessing of digitally acquired two-dimensional (2D) cineloops, and allows the operator to position one or multiple independent M-mode cursors freely on the 2D images. Initial clinical data show that anatomic M-mode can increase the reproducibility and accuracy of standard M-mode measurements of the left ventricle. Also, this quantitative technique has the potential to improve assessment of left ventricular wall motion and thickening, and could be particularly useful in providing objective measures during stress echocardiography.

Three-dimensional echocardiographic reconstruction: description and applications of a simplified technique for quantitative assessment of left ventricular size and function.

A simplified system for three-dimensional (3D) reconstruction of the left ventricle and quantitation of its size and function is described. This system requires the acquisition of a minimum number of two-dimensional (2D) echocardiographic apical views, which are obtained by rotation of the probe about the initial imaging point. Traced endocardial borders are spatially reconstructed according to the common apex and longitudinal axis of the views and to the measured or assumed angular relation between scanned planes. This technique has been applied in vitro to regular and irregular ventricular phantoms, yielding excellent accuracy for volume calculation. Also, it has been applied clinically for left ventricular volume, stroke volume, and ejection fraction calculation in both normal subjects and patients with various cardiac diseases, providing good results compared with other independent imaging techniques and showing increased accuracy with respect to 2D echocardiographic methods. Because this is obtained without substantial increase in time, effort, or cost, this simplified technique for 3D reconstruction should therefore be of value in daily clinical echocardiographic practice.

Hemodynamic effects of oral sotalol during both sinus rhythm and atrial fibrillation.

OBJECTIVES: This study investigated the hemodynamic effects of oral sotalol during both sinus rhythm and paroxysmal atrial fibrillation. BACKGROUND: The hemodynamic effects of most antiarrhythmic drugs have been characterized in subjects during sinus rhythm. However, there are no data concerning these effects on the paroxysmal tachyarrhythmias. METHODS: In 17 patients with paroxysmal atrial fibrillation and without heart failure (aged 62 +/- 11 years, ejection fraction 51 +/- 4%), an electrophysiologic-hemodynamic study was performed twice. In the first study, hemodynamic variables were evaluated both during sinus rhythm and after the induction of atrial fibrillation. Sotalol (160 or 240 mg/day) was administered for 6 to 7 days and the study was then repeated with the same methods. RESULTS: The drug significantly diminished heart rate during both sinus rhythm and atrial fibrillation. During sinus rhythm, sotalol did not change systemic pressures and significantly increased left and right ventricular end-diastolic, left and right atrial and pulmonary pressures. Cardiac index decreased, whereas stroke volume was unchanged after the drug. Ejection fraction and left ventricular end-diastolic and end-systolic volumes evaluated by echocardiography were unchanged after sotalol. During atrial fibrillation, the drug had less evident effects on cardiac function. Left ventricular end-diastolic, left atrial and pulmonary pressures did not increase significantly. CONCLUSIONS: The hemodynamic changes induced by oral sotalol appear to be mainly related to an involvement of ventricular distensibility; this effect is less evident during atrial fibrillation than during sinus rhythm. In patients with paroxysmal atrial fibrillation without heart failure treated with oral sotalol, a recurrence of the tachyarrhythmia is hemodynamically well tolerated.