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Transcript
Apex Echocardiography A Two-dimensional Technique for Evaluating Congenital Heart Disease NORMAN H. SILVERMAN, M.D., AND NELSON B. SCHILLER, M.D. With the technical assistance of Patricia A. Hart, M.A., R.D.M.S. Downloaded from http://circ.ahajournals.org/ by guest on June 17, 2017 SUMMARY We have evaluated apex echocardiography, using an 800 phased array sector scanner, in 368 patients with congenital heart disease. With the patient lying with the left side dependent, the transducer is placed over the apex of the heart and cross sectional images are obtained in the plane perpendicular to the cardiac septa and through the orifices of the mitral and tricuspid valves. In this view, the chambers are side by side and both atria and ventricles are separated by their respective septa and atrioventricular valves. Defects in the region of the septa can be detected. Congenital defects involving the atrioventricular valves, such as endocardial cushion defects, tricuspid atresia, and Ebstein's anomaly, can be defined. The location of the baffle after Mustard's operation for aortopulmonary transposition and intra-atrial structures, such as the membrane in cor triatriatum, can be seen. The position of the apex of the heart can be located in dextro, levo, or mesocardia by definition of the apex image. The relative size of the cardiac chambers can be compared. The localized thickness of the ventricular septum can be identified with the apex image. We have found this technique to be valuable in patients with congenital heart disease who are undergoing cross sectional echocardiography. TWO-DIMENSIONAL phased array sector scanners allow high resolution imaging of large cross sections of the heart from small echocardiographic windows. Conventionally, precordial window transducer placement has been used to produce the images."'' Alternative transducer application in the suprasternal notch,20 over the cardiac apex21 and subxyphoid areas allows alternative approaches for obtaining tomographic images of cardiac chambers. Using an 800 phased array sector scanner, we have used the apex as a locus from which to display simultaneously the four cardiac chambers, the atrioventricular valves, and the cardiac septa. Because of this unique presentation, this view has been useful in defining a wide variety of congenital heart defects. Patients We examined 368 patients, with ages ranging from newborn to adult, who had congenital heart disease. Apical cardiac images were performed as part of the two-dimensional echocardiographic examination. The diagnosis was established at cardiac catheterization in 218 of these patients. In the remainder, the diagnosis was made by clinical means, electrocardiography, roentgenography, and M-mode echocardiography. Examination Techniques The recording of the apical image requires precise positioning of the patient and application of the transducer to produce an optimal image (fig. la and b). The subject is positioned as for performance of an apexcardiogram, lying supine with the left side of the thorax dependent. When the cardiac apex is difficult to palpate, the transducer is applied to the apex region and moved around in this region until the precise image is obtained with the apex of the heart in the apex of the image. When the subject is lying on the left side, the apex may be very close to the bed; to compensate for this, we have constructed a 6-inch foam rubber mattress with a piece carved out that enables the transducer to be placed directly on the apex impulse. In patients with cardiac malposition, examination of the chest roentgenogram is helpful in defining the location of the cardiac apex. Once the apex is located, the tomographic plane is directed toward the base with the beam plane perpendicular to the ventricular and atrial septa and through the plane of the mitral and tricuspid valve orifices. Fine adjustment of gain settings and transducer position is required to produce an optimal image. Simultaneous display of both atria and ventricles, with the atrioventricular valves and cardiac septa, is sought (fig. 2). Angulation of the transducer slightly toward the base of the heart allows visualization of the pulmonary veins posteriorly and the aorta and right ventricular outflow tract anteriorly (fig. 3). In some patients in whom the studies were performed during cardiac catheterization, contrast echocar- Methods Equipment We performed the studies using a Varian Associates phased array sector scanner with an 800 scanning angle. The transducer has 32 elements with a frequency of 2.25 MHz and an active area of 1.2 by 1.3 cm. The line density of the image was either 64, 128 or 256 lines per arc and displayed at a tissue depth of 7, 15 or 21 cm. The images were displayed on an XY oscilloscope screen at 30 frames per second and recorded on video tape at a rate of 60 half-frames per second. This mismatch resulted in only a half density image per single frame recorded on the video tape. Single images could be recorded with a Polaroid camera mounted on a slave X-Y screen (full density frame), or from the video television screen. A centimeter grid for depth and breadth was displayed at the top and left side of the recorded image and an electrocardiogram was displayed below the image for reference to events within the cardiac cycle. From the Departments of Pediatrics and Medicine and the Cardiovascular Research Institute, University of California, San Francisco, California. Address for reprints: Norman H. Silverman, M.D., 1403-HSE, University of California, San Francisco, California 94143. Received September 16, 1977; revision accepted October 18, 1977. 503 504 CIRCU LATION VOL 57, No 3, MARCH 1978 h a Downloaded from http://circ.ahajournals.org/ by guest on June 17, 2017 FIGURE 1. a) Demonstration ofplacement of the transducer over the apex and the plane of the tomogram. The im age is displayed as if one were lookingfrom below in the position of the left hip showing the right a nd left a tria (RA and LA ) and the right and left ventricles (R V and L V). b) Section of the normal heart in the plane shown in (a) mounted as it appears on the television screen with the cardiac apex at top. L V left ventricle; RV - right ventricle; SEPT = interventricular septum; MV mitral valve; TV= tricuspid valve; LA left atrium; RA = right atrium; IAS= interatrial septurm. diography with a bolus of 2-5 ml of normal saline was performed to verify certain anatomic features. the tomographic plane from below. The apex of the ultrasonic fan contains the ventricular images, whereas the atria lie inferiorly. Display The images are displayed with the apex of the heart in the apex of the fan at the top of the screen and the atria at the bottom (fig. 2). Left-sided structures are to the right and right-sided structures are to the left of the observer. The image is displayed, therefore, as if one were observing the tomographic plane from the patient's left hip and looking at Results The Normal Image We examined 20 patients without heart disease. Figure 2 shows a stop frame image in a normal individual. The four chambers are displayed with the ventricles and atria lying FIGURE 2. Diagrammatic representation (left) of apical image (right). The stop frame is taken in early diastole. The right ventricle (R V) shows coarse trabeculation whereas the left ventricle (L V) is smooth. The tricuspid and mitral valves (TV, MV) are seen to be opening. The ventricular septum is seen between the two ventricles. The interatrial septum between the left and right atria (LA, RA ) is seen but echo dropout in the region of the fossa ovalis is present. The left pulmonary vein (PV) is identified. The electrocardiogram is seen below the image indicating the time and the cardiac cycle. APEX ECHOCARDIOGRAPHY/Silverman, Schiller Downloaded from http://circ.ahajournals.org/ by guest on June 17, 2017 side-by-side; the ventricles lie at the apex and the atria lie at the base of the fan. The ventricular and atrial septa and the atrioventricular valves form a cruciate confluence that divides the image into four sections. The ventricles are displayed in their long axes from the apex to the base and occupy approximately the upper two-thirds of the image, and the atria occupy the lower third. The left ventricle, noted on the right, is roughly ellipsoid in shape, with the mitral valve forming the flattened base. In this projection, the apex is formed mainly by the left ventricle with a much smaller contribution by the right, except in younger children where the right and left ventricles occupy similar portions of the apical image. The lateral wall of the left ventricular image is formed by the posterior portion of the left ventricular free wall, whereas the medial border is the ventricular septum. Papillary muscles sometimes can be defined by slight clockwise rotation of the transducer along its axis. In real time, the left ventricle is seen to contract concentrically. With the onset of diastole, the mitral valve leaflets are seen to separate abruptly and move into the left ventricle. The larger anterior leaflet is medial whereas the smaller posterior leaflet is lateral. The motion of the mitral leaflet in diastole is biphasic related to the phasic diastolic blood flow. The left side of the anterior portion of the image is formed by the sinus portion of the right ventricle (fig. 2). The right ventricle is seen in its long axis and is triangular in shape. The medial border of the right ventricular image is the ventricular septum, whereas the lateral part is the anterior right ventricular wall. The coarse trabeculations of the right ventricle and moderator band are identified as bright linear echoes in the apical area. The echo pattern within this area of the right ventricle is different from that of the left so that morphological identification of the right ventricle often can be made on the basis of this echo pattern. The tricuspid valve, like the mitral valve, forms the base of the triangular right ventricular image. Two leaflets of the tricuspid valve are seen; the anterior tricuspid leaflet is lateral whereas the septal leaflet is medial. In real time, the tricuspid valve, which lies at the same level as the mitral valve in diastole, moves in a manner similar to the mitral valve; in systole, the 505 size of the right ventricle diminishes, but the septum moves toward the left ventricle. The left atrium forms the inferior right quadrant of the image. The atrial outline is roughly circular and the upper arc of the image is formed by the mitral valve apparatus and anulus. The lateral portion of the left atrial wall forms the lateral border of the image. The inferior portion of the image is formed by the posterior left atrial wall and its junction with the pulmonary veins. The medial margin of the left atrium is formed by the interatrial septum. In real time, the left atrium is seen to expand and contract reciprocally with the left ventricle. The right atrium forms the lower left quadrant of the image (fig. 2). It, too, is circular in shape and is formed superiorly by the corresponding atrial walls. The medial wall is formed by the interatrial septum. In real time, the chamber is seen to contract and expand reciprocally with the right ventricle. The two atrioventricular valves lie on the same horizontal level and move with almost identical phasic motion. The image is divided into left and right halves by the ventricular and atrial septa. The ventricular septum is situated in the apex of the image and runs vertically; the septum joins the confluence between the mitral and tricuspid valves. The apical portion of the septum is the muscular septum, and the portion near the confluence between the atrioventricular valves is the membranous septum. Slight cranial and caudal angulation of the transducer also allows imaging of larger areas of both the interatrial and interventricular septa. With cranial transducer angulation, a left ventricular outflow tract is brought into view and, with further angulation, the aortic valve and its leaflets can be identified clearly (fig. 3). Atrial Septal Defects We examined 19 patients with secundum atrial septal defects, including four who had had closure by means of a patch. It is not possible, from the apical approach, to differentiate between normal echo dropout caused by thinness of the atrial septum in the region of the fossa ovalis (Rosenquist, personal communication) and secundum atrial FIGURE 3. Diagrammatic representation (left) of tomogram on the right. Cranial angulation of the transducerfrom the apex showing the aortic valve and leaflets. The tricuspid valve (TV) is seen to the left of the aortic valve. The right atrium (RA) and left atrium (LA) are separated by the interatrial septum. The ventricular septum is not imaged anteriorly because it moves out of thefield with this sweep and is replaced by the right ventricular outflow tract (R VO). Pulmonary veins are not seen in this still frame recording. CIRCULATION 506 VOL 57, No 3, MARCH 1978 A FIGURE 4. Apical image of an ostium primum atrial septal defect. The apex is made up of the right ventricle (R V) which is larger than the left ventricle (L V). The septum is rotated to the left by the enlarged ventricle in the absence of echoes from the interatrial septum. The dropout of echo from the atrial septum in the region of confluence with the mitral and tricuspid valves and ventricular septum is pathognomonic of primum type defects. Downloaded from http://circ.ahajournals.org/ by guest on June 17, 2017 septal defects. Detection of this defect has been verified by demonstrating the atrial patch postoperatively. We examined 12 patients with ostium primum atrial septal defects. In this lesion the echo dropout is different from that in secundum defects; it is situated lower in the atrial septum, adjacent to and involving the atrioventricular valve junction (fig. 4). Frequently, a bright echo is seen in the atrial septum which, we believe, arises from the free edge of the interatrial septum. The entire echo from the interatrial septum may be missing in this condition either because of associated secundum atrial septal defect or the normal septal echo dropout from the fossa ovalis region. We have not been able to detect mitral valve clefts from this view. In both types of atrial septal defects there are secondary changes in the size of the ventricles and ventricular septal motion. The enlarged right ventricle forms a proportionately larger portion of the apex image and the ventricular septum is displaced toward the subject's left. In real time the septal motion can be seen to contract in a paradoxical fashion. The right atrium occupies a considerably larger area than does the left atrium. In ostium primum defects with associated mitral incompetence, left atrial size also may increase. Atrioventricular Canal Defects We examined 24 patients with partial or complete atrioventricular canal defects. The apex view offers a unique image of these deformities. In complete atrioventricular canal defects there is absence of echoes from the upper portion of the ventricular septum. The extent of echo dropout gives an estimate of the size of the ventricular septal defect. The estimate of the size of the atrial component of the defect may be erroneously large because of dropout from the area of the fossa ovalis unless a bright echo from the free edge of the atrial septum can be identified. When there is a single anterior atrioventricular valve leaflet (Rastelli type C),22 a single linear echo is seen across the two ventricles (fig. 5). When the common leaflet is divided and attached to the crest of the ventricular septum (Rastelli type A),22 the echo from the common anterior leaflet is seen to be broken. In real time the motion of the echo from the two forms of defect is entirely different. With diastole in type C the undivided echo moves toward the ventricle in a single line whereas in the type where the common anterior leaflet is divided, the separate portions move toward their respective ventricles. We have not encountered any complete atrioventricular valve disorders of the Rastelli type B group. In partial endocardial cushion defects, the separate valve leaflets appear attached to the crest of the ventricular septum. Secondary anomalies in the size of the ventricles and the atria are displayed and help to define the hemodynamic consequences of the lesion. When there is a predominant left-to-right shunt at the atrial level, right atrial and right ventricular enlargement can be detected; when a large ventricular shunt is present, or FIGURE 5. Apical image of a patient with a complete atrioventricular canal, Type C of Rastelli. Note the area of echo dropout in the region of the ventricular septal defect. Rather than separate mitral and tricuspid valves, there is a linear echo from the an terior common atrioventricular valve leaflet. There is dropout of atrial septal echoes from the entire atrial septum. A pulmonary vein is identified posteriorly (PV). APEX ECHOCARDIOGRAPHY/Silverman, Schiller 507 FIG U RE 6. A pical view of a ventricular septal aneurysm. The diagram on the left is a diagrammatic representation of the echo tomogram on the right. In systole, the aneurysm is seen to prolapse into the right ventricle (R V) below the tricuspid valve (TV), arrowed in the diagram on the left. Downloaded from http://circ.ahajournals.org/ by guest on June 17, 2017 there is significant mitral regurgitation, the left-sided chambers also are enlarged. We have noted that, postoperatively, the position of the patch across the atrial and ventricular septal defects can be clearly defined as bright echoes from the synthetic material, Ventricular Septal Defects Idiopathic Hypertrophic Subaortic Stenosis There were 15 patients who had idiopathic hypertruphic subaortic stenosis. In this lesion the area of septal hypertrophy and its relationship to the left ventricular outflow tract can be identified by angling the transducer cranially toward the aortic valve (fig. 7). During the scan the septum is noted to thicken with the cranial angulation. The area of We examined 27 patients with membranous ventricular septal defects. The demonstration of the ventricular septum from the apex to its confluence with the interatrial septum allows identification and localization of defects. Exploration of a large part of the septum is possible by cranial and caudal angulation of the transducer. Larger membranous ventricular septal defects and those associated with tetralogy of Fallot (26 patients), truncus arteriosus (7 patients), and double outlet right ventricle (8 patients) can be identified. Smaller septal defects often cannot be seen. Postoperatively the ventricular septal patches used to close these defects can be identified because of their brighter echo characteristics. We have detected ventricular septal aneurysms in 10 patients (fig. 6). The aneurysm is located in the upper portion of the ventricular septum adjacent to the atrioventricular valve. These aneurysms cannot be differentiated from pouches associated with tricuspid valve in partial endocardial cushion defects" on the basis of the aneurysmal protuberance, but associated features of an endocardial cushion defect favor the diagnosis of a pouch of the tricuspid valve. In real time motion, the aneurysm is seen to prolapse into the right ventricle below the tricuspid valve with each ventricular systole and move toward a central position with ventricular diastole. Single Ventricle Complexes This view is helpful for differentiating large ventricular septal defects from single ventricle complexes. We have en-_ countered 12 patients with single ventricle complexes. Even in very large ventricular septal defects a rim of ventricular septum in the apex of the image can be identified, whereas in single ventricle complexes, even in the presence of a small outflow chamber, this endocardial protuberance dividing the 11 and not outflow chamber> from the ventricle is displaced readily identifiable from the apex view. Papillary muscles may be erroneously interpreted as being a rim of the ventricular septum. In addition, the definition of one or two atrioventricular valves in single ventricle complexes can be identified readily from the apex approach. 7. Cross-sectional ~~~~~~~~~~~~FIGURE patient with idiopathic The second and echocardiogram from the apex in a hypertruphic ubtructive cardiomyopathy. third frames show progressive angulation in a cranial direction through the left ventricular outflow tract. Note the ventricular septum appears to increase in thickness in successive cranial frames. The brightness of the septal echo appears stronger than the rest of the myocardium. CIRCULATION 508 maximal thickening of the septum and narrowing of the left ventricular outflow tract were identified by angling the transducer toward the aortic valve (fig. 7). In real time motion, the systolic anterior motion of the mitral valve is appreciated in this area, and can be identified by passing an M mode from the phased array system through this region. Portions of the mitral valve can be identified. The systolic narrowing of the left ventricular outflow tract also is identified in real time. The echo reflectance characteristics of the hypertrophic portion of the septum also appear to be different from the rest of the ventricular septum.24 Ebstein's Anomaly Downloaded from http://circ.ahajournals.org/ by guest on June 17, 2017 The apex view demonstrates the two atrioventricular valves lying side-by-side in the normal individual. We have examined 11 patients with Ebstein's anomaly of the tricuspid valve. The apex projection shows the displacement of the tricuspid valve into the right ventricle (fig. 8). The tricuspid portion of the atrioventricular crux is distorted because the valve is displaced anteriorly when compared to the mitral valve. The atrioventricular valve groove sometimes can be imaged simultaneously, displaying the area of atrialized right ventricle. Several features of this disorder can be appreciated from the image. Displacement of the tricuspid valve from the mitral valve indicates the area of the atrialized right ventricle and the size of the functioning VOL 57, No 3, MARCH 1978 right ventricle; the degree of right atrial dilatation also can be seen. The septal leaflet of the tricuspid valve is small and is the more displaced leaflet. The anterior leaflet is seen and is large (fig. 8a), but the posterior leaflet is not recorded. We have observed different degrees of tricuspid displacement in patients with this disorder. In one patient, after postoperative plication of the anterior leaflet of the tricuspid valve, we noted a reduction in the size of the atrialized right ventricle and an increase in the size of the functioning right ventricle (fig. 8b). Tricuspid Atresia In four patients with tricuspid atresia, the whole apical image was formed by the left ventricle. The size of the ventricular septal defect could be identified in some patients (fig. 9). Only a left-sided atrioventricular valve was detectable. The two atria are observed posteriorly with the right atrium appearing larger than the left. The relative degree of hypoplasia of the right ventricle in this disorder can be identified. The area of the tricuspid valve shows dense echoes but no tricuspid valve can be seen. Hypoplastic Left Heart Complexes In hypoplastic left heart complexes the presence or absence of a mitral valve and left ventricular cavity was detected in three patients. a b ATRIAUZ FIGURE 8. a) Apical cross-sectional echocardiogram of a patient with Ebstein's anomaly of the tricuspid valve. The tricuspid valve (TV) is displaced into the body of the right ventricle (R V). The anuli of the atrioventricular valves are on the same level and the mitral valve can be identified in the appropriate region in the right hand panel which is a stop frame recording. The area between the atrioventricular valve groove and the tricuspid valve is the atrialized right ventricle. b) Cross-sectional echogram from the patient shown in (a) after surgical plication of the an terior tricuspid valve leaflet. The area of atrialized right ventricle is diminished in size from the preoperative example. Note that the septal leaflet of the tricuspid valve is as displaced as in the preoperative pictures. APEX ECHOCARDIOGRAPHY/Silverman, Schiller 509 FioU RE 9. Cross-sectional echocardiogram from the apex in a case of tricuspid atresia. The left ventricle (L V) is large. Only one atrioventricular valve - the mitral valve (M V) - could be iden tified. A small ventricular septal defect ( VSD) comnmunicates with the small right ventricle (R V). The left atrium (LA) and pulmonary vein (PV) are seen posteriorly. The right atrium (RA ) is enlarged. The absence of echoes in the region of the atrial septum is technical and was present in other frames. Mustard's Operation into view the lower limb of the systemic venous atrium from the inferior vena cava to the mitral valve (fig. lOb). Areas of narrowing within these conduits can be detected. We examined 36 patients after Mustard's operation. The standard apical position identifies the pulmonary venous atrium from the area of the pulmonary veins through the tricuspid valve (fig. lOa). Slight caudal angulation brings Cor Triatriatum The fine membrane of cor triatriatum also has been detected in this view. The membrane lies within the atrium Aortopulmonary Transposition -The Intra-atrial Baffle after Downloaded from http://circ.ahajournals.org/ by guest on June 17, 2017 a V b FIGURE 10. Apical cross-sectional echocardiograms in a patient who had undergone Mustard's prooedure. a) The right ventricle (R V) is larger than the left ventricle (L V) and the interventricular septum is displaced. This frame is angled through the systemic venous atrium defining the pulmonary venous atrium (PVA) between the pulmonary veins (PV) and the tricuspid valve ( TV). The systemic venous atrium (SVA ) in this view is enclosed posteriorly by the baffle and anteriorly by the mitral valve. b) With slight caudal angulation the inferior limb of the systemic venous atrium (SVA) can be seen from the area of the inferior vena cava to the mitral valve. It is surrounded on both sides by the baffle (arrows). The pulmonary venous atrium (PVA) is located on both sides of the baffle. Posteriorly it joins with the confluence of the pulmonary veins and anteriorly lies between the baffle and the tricuspid valve. CI RCU LATION 510 VOL 57, No 3, MARCH 1978 FIGURE 1 1. Apical cross-sectional echocardiogram in a patient with cor triatriatum. The diagram is on the right to define the unretouched echogram on the left. The membrane is identifled behind the mitral valve (MV). The left atrium (LA) is enlarged. Downloaded from http://circ.ahajournals.org/ by guest on June 17, 2017 behind the mitral valve. In real time the membrane is seen to toward the ventricle with the onset of ventricular diastole, and the area between it and the mitral valve leaflet enlarges (fig. I 1). After surgical removal of the membrane, this echo was no longer present behind the mitral valve. move Anomalous Pulmonary Venous Drainage Because the pulmonary veins can be seen readily to drain into the left atrium, this view appears useful in defining the presence of total anomalous pulmonary venous drainage. We examined three patients with total, and three with partial anomalous pulmonary venous connection. In one patient with total anomalous pulmonary venous drainage in whom a catheter was passed into the left vertical vein at catheterization, the echocardiographic image failed to show the confluence of the pulmonary veins with the left atrial wall. On injecting saline contrast material into the vertical vein, the right atrium was seen to fill before any left atrial filling. In a patient with partial anomalous pulmonary venous connection associated with the polysplenia syndrome, only left pulmonary veins were seen to enter the left atrium. These findings were confirmed at cardiac catheterization. It does not appear to be possible to image the upper pulmonary veins from the apex and abnormalities discovered have been of the lower veins only. Ventricular Size and Contraction The apical view enhances the ability to observe ventricular contraction, especially when combined with other techniques of transducer placement. One of the chief advantages is the ability to define large areas of the ventricular walls, especially in the right ventricle. The relative and absolute sizes of the ventricles can be detected (figs. 4, 5, 8-10). The identification of the coarse trabeculation and moderator band identifies the morphological right ventricle which aids delineation of situs problems where the ventricular inversion is suspected. The detection of the apex by echocardiography defines not only levocardia, but mesocardia (two patients) and dextrocardia (eight patients). Discussion The technique of apex echocardiography has augmented our perception of two-dimensional echocardiographic imaging. We have found that the technique for applying the transducer to the apex impulse locus is no more difficult than obtaining precordial images and less difficult than suprasternal and subxyphoid imaging. For that matter, it is also less difficult than properly applying a pressure transducer for performing an apexcardiogram. Whereas the wide, electronically-generated scanning arc provides a sufficiently large sector to apically image the entire heart, we have been able to use smaller mechanically-generated sectors to image portions of the apex views. Our attempts with the linear array transducers have suggested that they are not suitable for generating this projection because of the small size of the apical echocardiographic window and the relatively large size of the transducers. The apical ultrasonic tomogram that we describe is similar to the clavicular hepatic angiographic projection used by Bargeron and his colleagues. These clavicular hepatic views are similar to the hemiaxial views used for coronary angiography. Among the unique features of the apex approach is the ability to define each ventricle in its long axis. Preliminary assessment of the use of the apical approach in biplane left ventricular volume determination has suggested that this approach is feasible.25 This view also affords demonstration of a much larger area of the right ventricle than other precordial echocardiographic views. This feature of the projection has considerable value in that it is possible to analyze the left and right ventricles for size and position by a side-by-side comparison. Not only is it useful for assessing ventricular size but also relationships of position of the two ventricles. We have found that degrees of anterior angulation and long axis rotation have produced additional useful information. For example, with superior-to-inferior angulation in the apical position it is possible to explore most of the interventricular septum, to image the confluence of the pulmonary veins, to explore the venous and systemic limbs of the intra-atrial baffle of Mustard, to image the aortic root APEX ECHOCARDIOGRAPHY/Silverman, Schiller Downloaded from http://circ.ahajournals.org/ by guest on June 17, 2017 and valve leaflets and to explore the interatrial septum and right ventricular outflow tract. This approach to evaluating aortic valve leaflet morphology previously has been reported with the M-mode technique.26 Rotation of the transducer along its long axis a full 900 produces another unique view of the heart, the right anterior oblique equivalent.27 This view is more useful in the adult and has the unique echocardiographic feature of imaging the anterolateral and inferior walls of the left ventricle. This view has been used with the precordial short axis for noninvasive biplane volume determination.25 Because this view affords another approach to define atrial structures, we surmise that it will be useful to study forms of left ventricular inflow obstruction such as supravalvar mitral rings and atrial myxomas causing mitral obstruction. Mitral stenosis and prolapse also are readily detected in this view, but we have relied on more conventional views to evaluate these deformities. The presence of vegetations on the atrioventricular valves can be detected readily from this plane augmenting their localization to a specific valve leaflet. Our preliminary experience with higher frequency transducers and instruments that allow the image size to be increased suggest that these innovations will be valuable for studying small children and infants. Appropriate magnification of the image in small children is required to produce an adequate image. The technique of apex echocardiography has greatly augmented our two-dimensional perception of echocardiographic images in congenital heart disease. With a number of lesions, it appears to be the most valuable view for delineation and often is easier to record than conventional precordial images. Acknowledgment We wish to thank Drs. Abraham Rudolph and Paul Stanger for their advice, criticism, and support. References 1. Griffith JM, Henry WL: A sector scanner for real-time two-dimensional echocardiography. Circulation 49: 1147, 1974 2. Henry WL, Griffith JM, Michaelis LL, McIntosh CL, Morrow AG, Epstein SE: Measurement of mitral orifice area in patients with mitral valve disease by real-time, two-dimensional echocardiography. Circulation 59: 829, 1975 3. Weyman AE, Feigenbaum H, Hurwitz RA, Girod DA, Dillon JC, Chang S: Localization of left ventricular outflow obstruction by cross-sectional echocardiography. Am J Med 60: 33, 1976 4. 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N H Silverman and N B Schiller Downloaded from http://circ.ahajournals.org/ by guest on June 17, 2017 Circulation. 1978;57:503-511 doi: 10.1161/01.CIR.57.3.503 Circulation is published by the American Heart Association, 7272 Greenville Avenue, Dallas, TX 75231 Copyright © 1978 American Heart Association, Inc. All rights reserved. Print ISSN: 0009-7322. Online ISSN: 1524-4539 The online version of this article, along with updated information and services, is located on the World Wide Web at: http://circ.ahajournals.org/content/57/3/503 Permissions: Requests for permissions to reproduce figures, tables, or portions of articles originally published in Circulation can be obtained via RightsLink, a service of the Copyright Clearance Center, not the Editorial Office. Once the online version of the published article for which permission is being requested is located, click Request Permissions in the middle column of the Web page under Services. 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