Transducer Angulation Research Articles

English

Echocardiography is a unique non-invasive application of ultrasound for imaging of living heart. It is based on detection of echoes produced by a beam of ultrasound pulses transmitted into the heart. Conventional echocardiographic modalities include two-dimensional (2D), M-mode and Doppler modes. M-mode is the first ultrasound modality used in which the ultrasound beams are aimed manually at selected cardiac structures to give a graphic recording of their positions and movements. M-mode recordings permit quantitative measurement of cardiac dimensions and detailed analysis of complex motion patterns depending on transducer angulation. It facilitates analysis of time relationships with other physiological variables such as echocardiographic, heart sounds, and pulse tracings, which can be recorded simultaneously. However, it cannot be used to measure velocity, the direction or type of the blood flow but can be combined with contrast or colour-coded Doppler studies for accurate timing of flow events. Variations in M-mode echocardiographic parameters with breed, age, sex and body weight occurs and need to be kept in mind while interpreting the findings. Its variables are usually subjected to change and needs experienced sonologist to diagnose any condition. The present review covers the M-mode echocardiographic developmental history in general and its diagnostic role for dogs in particular.   Key words: M-mode, echocardiography, dogs, ultrasound.

M-Node Echocardiographic Assessment of D-Transposjtjon of the Great Arteries and Associated Defects

INTRODUCTION: M-mode echocardiography has proven to be a reliable means for the diagnosis of d-transposition of the great arteries (8, 5). The M-mode echo diagnostic criteria are the demonstration of: (1) an anterior aorta, identified by delayed opening of its semilunar valve compared to the pulmonary valve, and (2) the aorta being situated rightward and anteriorly vis-a—vis the posterior pulmonary artery. MATERIAL AND METHODS: Forty—one patients with d-transvositjon of the great arteries were studied prior to, and 73 following Mustard operation and correction of associated lesions. Seventeen patients had sequential pre- and postoperative echocardio— graphic and cardiac catheterization studies. The echocardiograrns were obtained within 24 hours of cardiac catheterization. Hemodynamic data were obtained at cardiac catheterization using fluid—filled catheters and Statham gauge pressure transducer prior to the angio-graphic studies. Right ventricular angio— graphic volumes and ejection• fractions were obtained in 18 patients using Simpson’s method (7). Superior vena caval, right ventricular and left ventricular selective cineangiograms were also obtained. RESULTS: Preoperative Studies Forty-one patients with d-transposition of the great arteries were studied prior to the Mustard operation and correction of associated lesions. The echocardiographic and hemodynamic data of these patients are presented in Table 1. The age ranged between 1 day and 13 years (mean 3.2±4.2 years). Preoperatively, the PEP/RVET ratio was > 0.50 in only one patient; postoperative1y,.the ratio was 0.50 in 4 patients and in 2 of these hemodynamically significant tricuspid regurgita‘ don and angiographically estimated reduced ejection fraction (0 . 50) was noted. DISCUSSION: This study confirms that M-mocle echocard iography is a reliable means for diagnosing d-transposed great arteries. The transducer angulation (from the standard 4th intercostal parasternal space) required to detect the transp osed aorta is rightward and anterior (toward the right shoulder) from the posterior vessel, as opposed to an anterior and leftward angulation required to detect the anterior vessel (pulmonary Artery) in normally related great vessel.In summary, M-mode echocardiography prov ides not only a reliable means of diagnosing d-transposition of the great arteries, but is also useful for assessing the presence of associated lesions. Changing hemodynamic parameters in patients with transposition of the great arteries can be followed before and after the Mustard operation by longitudinal echocardiographic ass essment -

Myocardial Rotation but Not Circumferential Strain Is Transducer Angle Dependent: A Speckle Tracking Echocardiography Study

Doppler derived strain analysis has been shown to be angle dependent. Speckle tracking analysis using 2D echocardiographic images is thought to provide angle independent parameters of regional and global myocardial function. This study sought to evaluate whether myocardial circumferential strain and rotation derived from automatic frame-by-frame tracking of natural acoustic markers is dependent on angulation of the transducer. In 48 healthy volunteers (mean age 36 ± 3 years, 20 male) parasternal short-axis views at apical level were obtained as follows: at the standard parasternal position (5th intercostal space) with a most possible circular short-axis image of the left ventricle (angulation 1), at an angulation of the transducer by 20° from this standard position to the apex (angulation 2) and at an angulation of the transducer by 20° to the base of the left ventricle (angulation 3). Using an automatic frame-by-frame tracking system of natural acoustic echocardiographic markers (EchoPAC, GE Ultrasound, Horton, Norway) circumferential strain and rotation were calculated for six segments within a short-axis circumference. Image quality was sufficient for acquisition and analysis of images at all three-transducer angulation in 90% of the analyzed segments. Rotation was measured to be 7.7 ± 1.2° at angulation 1, 2.7 ± 0.9° at angulation 2 and 4.3 ± 1.1° at angulation 3 (p < 0.05). Average circumferential strain data was found to be -27.2 ± 5.1% at angulation 1, -26.5 ± 3.8% at angulation 2 and 28.9 ± 4.4% at angulation 3 (p = 0.287). Circumferential strain analysis is not dependent on transducer angulation. In contrast, determination of myocardial rotation is dependent on transducer angulation. Therefore, accurate transducer angulation has to be taken care of if rotation measurements are performed.

Ultrasound imaging of the airway

To the Editor, We read with interest the articles by Tsui et al. regarding ultrasound imaging of the airway using a sublingual scanning approach. A small footprint high frequency curved transducer placed intra-orally failed to capture images of the epiglottis and the laryngeal inlet due to posterior acoustic shadowing of the hyoid bone. Transcutaneous ultrasound scanning of the airway may overcome some of these challenges. In our pilot study, we were able to image airway structures in the transverse and parasagittal (1 cm away from midline) views using a linear 38 mm, 13–6 MHz transducer with the Sonosite M-Turbo ultrasound machine (Bothell, WA, USA). The epiglottis can be visualized (Fig. 1) through the transverse and parasagittal windows both above and below the hyoid bone. Because the hyoid bone casts an acoustic shadow posteriorly, part of the epiglottis is obscured. The epiglottis is best seen through the hyo-thyroid window between the hyoid bone and the thyroid cartilage. It appears as a hypoechoic structure with a curvilinear shape on parasagittal view and an inverted ‘C’ on transverse view. It is related anteriorly by the hyperechoic triangular preepiglottic space and lined posteriorly by a hyperechoic air–mucosa interface. Compared with the sublingual technique, the transcutaneous scan has several advantages. A high frequency transducer for transcutaneous scan captures images of higher resolution. A good transducer to skin contact can be maintained even at the level of the thyroid prominence with the linear transducer in the parasagittal position. Visualization of the epiglottis is possible without ultrasound beam interference due to hyoid acoustic shadow and attenuation by hypopharyngeal air (as seen with the sublingual scan). Furthermore, airway scanning at the level of the laryngeal inlet is possible and not impaired by restricted caudad transducer angulation due to the presence of upper incisors or the smaller capacity of the sublingual space (as seen with the sublingual scan). Both scanning approaches visualize tongue substance and musculature. Future studies will determine if the sublingual and transcutaneous approaches are complementary to each other. Ultrasound may prove to be an exciting evaluation tool for airway structures and ease of intubation.

Three-Dimensional Trajectory Assessment of an IVUS Transducer From Single-Plane Cineangiograms: A Phantom Study

The recovery of the three-dimensional (3-D) path of the transducer used during an intravascular ultrasound (IVUS) examination is of primary importance to assess the exact 3-D shape of the vessel under study. Traditionally, the reconstruction is done by simply stacking the images during the pullback, or more recently using biplane angiography to recover the vessel curvature. In this paper, we explain, how single-plane angiography can be used with two projection models, to perform this task. Two types of projection geometry are analyzed: weak-perspective and full-perspective. In weak-perspective projection geometry, the catheter path can be reconstructed without prior transducer depth information. With full-perspective projection geometry, precise depth location of reference points are needed in order to minimize the error of the recovered transducer angle of incidence. The transducer angulation reconstruction is based on the foreshortening effect as seen from the X-ray images. By comparing the measured to the true transducer length, we are able to get its incidence angle. The transducer trajectory is reconstructed by stitching together the different estimated angulations obtained from each image in a cineangiogram sequence. The method is described and validated on two helical vessel phantoms, giving on average a reconstructed path that is less than 2 mm distant from the true path when using full-perspective projection.

Prosthetic mitral regurgitation can be mimicked by Doppler color flow mapping: Avoiding misdiagnosis

Objectives We sought to characterize a region of apparent systolic flow resembling mitral regurgitation (MR) in patients with mechanical disk mitral prostheses as artifact. Background Diagnosing MR in the presence of mechanical prostheses is challenging. Occasionally, important MR is suggested by a substantial region of systolic Doppler color flow in an acoustically shadowed region of the left atrium when, in fact, only trace MR exists. We hypothesized this pseudo-MR is caused by acoustic mirroring of the left ventricular outflow tract (LVOT) flow by sound reflected off the prosthesis, projecting flow into the left atrium because of longer transit time. Methods We reviewed 19 patients with mechanical mitral valves and trace MR by transesophageal echocardiography who had transthoracic echocardiography studies within 1 week (group A), and prospectively studied 22 consecutive patients by transthoracic echocardiography with subtle transducer angulation variation to detect pseudo-MR and characterize it by pulsed Doppler (group B). Results In group A, 12 of 19 patients had evidence of pseudo-MR on review of their transthoracic echocardiograms, absent by transesophageal echocardiography. In group B, this pseudo-MR signal was present in 13 of 22 patients, with velocity and timing by pulsed Doppler comparable with LVOT flow (onset at 125 ± 27 milliseconds vs 135 ± 11 milliseconds from QRS, P = not significant). The angle between the mitral plane and the LVOT, which determines whether this mirroring can occur, was smaller for patients with pseudo-MR. Conclusion Artifactual pseudo-MR is often seen with mechanical mitral prostheses. Its behavior and sensitivity to geometric relationships are consistent with mirroring of LVOT flow. Practically, potential misdiagnosis can be readily avoided by pulsed Doppler sampling, sparing the patient further procedures.

Doppler echocardiography for the estimation of cardiac output with exercise.

Insights into both normal and pathological cardiac responses to exercise have been hampered by lack of a safe, accurate, feasible means of estimating cardiac output (Q) during high-intensity and maximal exercise. Doppler ultrasound noninvasively measures blood velocity as it exits the heart and can be performed during exhaustive exercise without interference of the subject or need for steady state. From the product of aortic blood velocity and cross-sectional area of the aorta, stroke volume (SV) can be calculated. Despite these advantages of the Doppler technique, a number of potential sources of error have raised concern regarding the accuracy of this method. These include transducer angulation, change in aortic cross-sectional area during exercise, turbulence and alteration of a flat velocity profile in the aorta with increased Q, and uncertainties regarding the proper location for measurement of aortic outflow area. The magnitude of the influence of these potentially confounding variables on the accuracy of SV measurements determined by the Doppler technique is unknown. Estimates of both construct and concurrent validity suggest that the overall error may be small. Test-retest studies have indicated a high level of reliability with this technique.

Loss of contrast intensity during systole in the left ventricular cavity with the use of the contrast agent Albunex. An analysis of its correlation with pressure and velocity.

Several investigators have observed a decrease in video intensity in the left ventricular cavity during systole when using contrast echocardiography. It has been suggested that this phenomenon is related to microbubble instability. The authors propose that this phenomenon is, in part, related to the effects of pressure and velocity on the acoustic reflectance of ultrasound contrast agents. Using an in vitro flow tube model and varying concentrations of Albunex contrast agent, the effects of pressure and velocity on microbubble video intensity were investigated. Velocity and pressure were varied independently and the imaging tube was scanned using three transducer frequencies at different concentrations of Albunex. Contrast video intensity was analyzed using high and low velocities (at constant pressure) and high and low pressures (at constant velocity). In addition, the fluid from the system was collected and imaged in a nonflowing reservoir tank to investigate the video intensity of the microbubbles when exposed to variable velocity and pressure. The video-intensity measurements were inversely and irreversibly related to ambient pressure changes (independent of velocity) in a tube model. However, video intensity varied inversely but reversibly with velocity (independent of pressure). This observation could not be explained simply by the "laminar flow" theory, by a change in transducer angulation, nor by a change in ultrasound imaging frame rate. This phenomenon was limited to Albunex microbubbles and was not observed with a contrast medium (corn starch) devoid of the acoustic properties of Albunex.

Pitfalls in the echo-Doppler diagnosis of hypertrophic cardiomyopathy.

While Doppler echocardiography has become the gold standard for the diagnosis of hypertrophic cardiomyopathy, there are many pitfalls in its use. Some of these pitfalls are technical in nature resulting from inadequate image quality, incorrect transducer angulation, and improper equipment settings. Other pitfalls relate to the diversity and heterogeneity in defining hypertrophic cardiomyopathy and to the host of disorders that may mimic it by echocardiography. The pattern and extent of ventricular hypertrophy, systolic anterior motion of the mitral valve, and Doppler determination of left ventricular outflow tract obstruction, diastolic dysfunction, and mitral regurgitation are discussed, as are wall-motion abnormalities and myocardial echo reflectivity. While these echocardiographic features of hypertrophic cardiomyopathy are nonspecific when seen in isolation, their combined presence in the appropriate clinical setting makes the diagnosis likely.

Two-dimensional echocardiographic evaluation of persistent truncus arteriosus

Using a phased-array, wide angle sector-scanner, 2-dimensional echocardiograms were obtained in 3 patients with persistent truncus arteriosus. Type I was found in 2 patients and type II in 1 patient. In the patient with type II truncal valve stenosis was also present. Using a combination of short-axis views at the cardiac base, with 30 ° superior transducer angulation and parasternal long-axis views, the truncus arteriosus and the pattern of pulmonary arteries were demonstrated in each case.

Distortions of ultrasonic field introduced by the rib cage in echocardiography.

In ultrasonic examination of the heart, the anatomy and motion of heart structures can be observed by placing the ultrasonic transducer over an intercostal window adjacent to the sternum. The ultrasonic beam may be reflected, refracted, or scattered from its path by the ribs and soft tissues before reaching the target of interest. This interaction between the tissues and ultrasound beam, which introduces significant changes in ultrasonic beam characteristics, may result in considerable degradation of the lateral resolution of the ultrasonic system, determined largely by the beam width. In this paper, the effect of rib cage on the beam characteristics is examined. It is shown that the rib cage can produce severe distortions of the ultrasonic beam, namely, asymmetry in beam cross-section, alteration in beam diameter, and deflection of the beam from its central path. It is also demonstrated that this distortion is dependent upon transducer diameter, width of the intercostal window, and transducer angulation relative to the breast plate.

M-mode echocardiographic assessment of D-transposition of the great arteries and associated defects.

M-mode echocardiographic, hemodynamic, and angiographic correlations are presented for 97 patients with d-transposition of the great arteries. Forty-one patients were studied before and 73 patients after the Mustard operation; 17 patients were studied sequentially before and after the Mustard operation. The echocardiographic diagnosis of d-transposition could be made with high accuracy by using two criteria: (1) opening of the posterior semilunar valve earlier than the anterior semilunar valve, and (2) location of the anterior semilunar valve to the right of the posterior semilunar valve with transducer angulation toward the right shoulder. In the pre-Mustard group the presence of associated lesions such as patent ductus arteriosus and ventricular septal defect was suggested by an elevated left ventricular end-diastolic/right ventricular end-diastolic dimension ratio (>1.2). In the post-Mustard group, after correction of shunting lesions, this ratio was similar to that in patients with intact ventricular septum. In pre-Mustard patients the anatomically fixed type of left ventricular outflow tract stenosis was suggested by a left ventricular outflow tract/pulmonary artery ratio of less than 0.5. This ratio was 0.52±0.1 in those in whom resection of the anatomic stenosis and Mustard operation were performed. Right ventricular function could be assessed by the pre-ejection period/right ventricular ejection time ratio; a ratio of greater than 0.5 was associated with angiographically determined ejection fraction of 0.5 or less.

Reproducibility of left ventricular internal dimensions with M mode echocardiography: Effects of heart size, body position and transducer angulation

Analysis was made of the variables of heart size, body position and transducer angle affecting the reproducibility of left ventricular internal dimensions as measured with M mode echocardiography. Echocardiograms were recorded in 24 subjects as the thorax was incrementally rotated and tilted. Transducer angle was noted from a three plane level attached to the probe. Constants were the technician, transducer placement and the interpreter. Heart rates varied insignificantly; respirations were held. Groups A and B were defined by their initial left ventricular internal dimensions at end-diastole (LVID d): 49 ± 5.9 and 73 ± 8.6 mm (group mean ± standard deviation). With body position constant the measurement error between duplicate recordings of LVID d was ± 1.2 mm (coefficient of variation = 1.8 percent) in Group A and ±4.5 mm (coefficient of variation = 4.6 percent) in Group B (p <0.001). Transducer angle varied 12 ° between duplicate recordings in both groups. As the position of the thorax changed, the transducer followed, maintaining approximately the same incline with the chest wall. In both groups errors for combined LVID d recorded with rotation and tilt, respectively, were unchanged from the duplication error. Thus, when the spatial orientation between the transducer and heart is held constant, it is the size of the heart that determines the reproducibility of the measurement of left ventricular internal dimensions.

113 TWO-DIMENSIONAL ECHOCARDIOGRAPHY (2D ECHO) IN THE CLOSED CHEST NEWBORN LAMB: METHODOLOGY AND ANATOMICAL OBSERVATIONS

Echocardiography has not been applied to investigation of cardiac anatomy or function in newborn experimental animals. Consequently, we have investigated the feasibility of 2D Echo for cardiac imaging in the conscious closed chest lamb.M-mode and 2D Echo studies were obtained from 16 closed-chest recumbant lambs: (age=120 days gestation-term-3 weeks; wt=1.8-8 kg). All cardiac chambers and valves were consistently and successfully imaged by transducer angulation from a left and a right precordial position. Cardiac structures were verified by constrast echo using selective injections of green dye and echocineangiographic studies. In addition, postmortem examinations demonstrated anatomical relationships and the orientation of cardiac chambers to the echo transducer. The ventricles are in a “side by side” position and optimal imaging of the left ventricular “long axis” was obtained from a right thoracic position. Complete study was readily accomplished in 10-20 minutes.We have examined the relevant anatomical relationships and developed a method for chronic M-mode and 2D echo study of the conscious closed chest lamb. It is believed that echo can be used for the investigation of cardiac function in animal models simulating human neonatal cardiopulmonary distress. Such application could potentially expand the role of echocardiography in the human neonate.

Effect of rib cage on the beam profiles of ultrasonic transducers

In multidimensional echo imaging of the heart, the anatomy and motion of the heart structures can be observed by placing the transducer over the intercostal window. The ultrasonic beam may be scattered, reflected or refracted from its path by the ribs and soft tissues between them. Since beam distortion is directly related to the loss of resolution in pulse‐echo imaging systems, an investigation of the effects of these intervening tissues on the ultrasonic beam characteristics may be useful for establishing criteria for selecting suitable transducers in clinical scanning procedures. In order to address this problem, an automated system for rapid mapping of transducer field based on a microcomputer has been developed in our laboratory. In this paper, we will present the initital results on our investigation of the beam distortions produced by the rib cage in terms of 3‐dimensional display of the intensity contours at various distances from the transducer. Also to be discussed is the effect of transducer angulation in relation to the breast plate on the transmitted ultrasonic beam.

A new approach to visualize the left main coronary artery using apical cross-sectional echocardiography

Patients undergoing coronary arteriography were studied to evaluate the feasibility of use of cross-sectional echocardiography to detect the left main coronary artery. Visualization of the left main coronary artery from the cardiac apex was attempted using a cranial transducer angulation. With this approach, the left main coronary artery was adequately visualized in 27 of 35 consecutive patients (77 percent) who were prospectively evaluated; in 12 of the 27 the bifurcation was clearly seen. In 26 of the 27 patients cross-sectional echocardiography correctly assessed the patency of the left main coronary artery as judged with coronary angiography. One patient had a false positive echocardiographic study; there were no false negative studies. A comparison of the short axis versus apical cross-sectional techniques in another group of 30 patients revealed the superiority of the apical approach in visualization of the left main coronary artery and its bifurcation; combined use of both techniques allowed for a 93 percent (rate of) success. Thus, apical cross-sectional echocardiography permits visualization of the left main coronary artery and its bifurcation and, therefore, has the potential for detecting left main coronary obstructive lesions.

Echocardiographic Interpretation of Pericardial Effusion

Echocardiography has proved to be quite useful in the detection of pericardial effusion. As little as 15 ml of fluid within the pericardial space can be detected. Specific signs of pericardial effusion, such as electrical alternans and paradoxical pulse, have become better understood by echocardiographic study. Yet, with all the benefits of echocardiography, the detection of pericardial effusion still may be quite difficult if careful attention is not given to technique. False-positive diagnosis of anterior pericardial effusion can be seen with epicardial fat pad, pericardial cyst, or foramen of Morgagni hernia. False-positive posterior pericardial effusion can be seen in large left pleural effusion, calcified mitral anulus, or excessively medial transducer angulation. New "switched-gain" circuits have helped detection of pericardial effusion by enhancement of pericardial echoes.

Echocardiographic interpretation of pericardial effusion

Echocardiography has proved to be quite useful in the detection of pericardial effusion. As little as 15 ml of fluid within the pericardial space can be detected. Specific signs of pericardial effusion, such as electrical alternans and paradoxical pulse, have become better understood by echocardiographic study. Yet, with all the benefits of echocardiography, the detection of pericardial effusion still may be quite difficult if careful attention is not given to technique. False-positive diagnosis of<i>anterior</i>pericardial effusion can be seen with epicardial fat pad, pericardial cyst, or foramen of Morgagni hernia. False-positive<i>posterior</i>pericardial effusion can be seen in large left pleural effusion, calcified mitral anulus, or excessively medial transducer angulation. New "switched-gain" circuits have helped detection of pericardial effusion by enhancement of pericardial echoes. (<i>Arch Intern Med</i>138:622-625, 1978)

Echocardiographic spectrum of mitral valve motion in children with and without mitral valve prolapse: The nature of false positive diagnosis

To examine problems in echocardiographic diagnosis of mitral valve prolapse, multiple crystal cross-sectional echocardiography and single crystal recordings derived from the multiple crystal array were used to study 45 clinically normal children aged 3 to 15 years (Group A), 26 children aged 2 to 10 years with known mitral valve prolapse (Group B), 12 children with a catheterization-proved large left to right shunt at the ventricular level (Group C) and 8 children with catheterization-proved left ventricular outflow tract obstruction (Group D). Children in Groups A and B were not studied hemodynamically. Children in Groups C and D had no evidence of mitral valve prolapse on angiography and were studied echocardiographically to determine the effect of changes in ventricular shape on the patterns of mitral valve motion. In the real time cross-sectional studies, normal patients demonstrated a spectrum of mitral valve motion in which the bodies of the anterior and posterior leaflets became slightly horizontal with systolic ejection. The mitral apparatus assumed a curvilinear funnel shape. Arching of the leaflets into a horizontal configuration was more striking in the presence of either left ventricular dilatation in left to right shunt or involvement of the anterior mitral anulus in subaortic stenosis (two patients) and was associated with false positive M mode tracings suggesting mitral valve prolapse. This latter configuration was easily differentiated from the superior motion of the body of the leaflets in true prolapse. Studies of single crystal M mode recordings derived form the cross-sectional array in known locations from six normal patients revealed M mode patterns of pseudoprolapse in tracings derived from the leaflet body and patterns of normal motion at the free edge. In contrast, superior-posterior prolapse visualized in cross-sectional studies in patients with the click-murmur syndrome was associated with abnormal M mode recordings from all parts of the leaflet, including the free edge, although the abnormalities were most striking in tracings derived from the leaflet body. The M mode echocardiographic findings of mitral valve prolapse in both normal patients and patients with the click-murmur syndrome were dependent upon transducer angulation and the portion of the valve examined. The critical differentiation of the spectrum of normal valve motion from prolapse requires careful evaluation of echoes from the free edge of the leaflet where the posterior and anterior leaflet echoes coapt in early systole.

Mitral valve prolapse in one hundred presumably healthy young females.

Clinical, electrocardiographic, phonocardiographic, and echocardiographic examinations were performed in 100 presumably healthy young females. Treadmill testing and ambulatory electrocardiographic monitoring were performed in a selected group of these subjects. Phonocardiograms, recorded with the subjects supine at rest, after inhalation of amyl nitrite, and in the upright position, revealed a 17% incidence of nonejection clicks and/or late or mid- to late systolic murmurs (PHONO-MSCLSM). Echocardiographic studies were performed in the second, third, fourth, and fifth intercostal space with emphasis on the importance of transducer angulation on the chest. Studies obtained with the transducer perpendicular to the chest in the sagittal plane, or pointing cephalad at a time when both mitral leaflets and left atrium are recorded, are optimal to study the mitral valve systolic motion. With the transducer in this position, 21 subjects were found to have pansystolic or late systolic prolapse, as previously defined on the echocardiogram. The presence of these echocardiographic findings was statistically related to the presence of PHONO-MSCLSM. Other echocardiographic patterns were identified and their relation to PHONO-MSCLSM and transducer position is discussed. Ten subjects with both echocardiographic evidence of mitral valve prolapse and PHONO-MSCLSM were identified (group EP), while 18 other subjects had either echocardiographic or phonocardiographic findings suggestive of mitral valve abnormality (group EorP). Seventy-two subjects had no abnormality (group noEP). The incidence of various clinical, electrocardiographic, and echocardiographic findings in these three groups was determined. Some findings said to be common in patients with proven mitral valve prolapse were seen more frequently in group EP subjects. Echocardiographic and phonocardiographic findings suggesting mitral valve abnormalities were found more commonly than expected in a population of presumably healthy young females.