Echocardiography in the Diagnosis of Congenital Heart Disease

Symposium on Pediatric Cardiology

Echocardiography in the Diagnosis of Congenital Heart Disease

Elliot Chesler, M.D., F.R.C.P. (Edin.),* Hymie S. Joffe, M.Med. (Paed.),** Walter Beck, M.Sc., M.Med., M.R.C.P. (Lond.), F.A.C.C.,t and Velva Schrire, M.Sc., Ph.D., M.D., F.R.C.P. (Edin.), F.R.C.P., (Lond.), PA.C.C.t

Current methods of investigation of patients with congenital heart disease involve the use of complex techniques and equipment, which not infrequently expose patients to discomfort and risk. The advantages of employing a technique that is safe, furnishes reliable information, and may be used repeatedly, even in seriously ill patients, are obvious. It is not surprising, therefore, that echocardiography has attracted so much attention, since it fulfills these requirements. The role of ultrasound in cardiology has been confined largely to the evaluation of patients with acquired heart disease. The pioneering work of Edler, Hertz, and Effert7-9.11-13 introduced ultrasonic methods of recording echoes from the anterior leaflet of the mitral valve, and the normal pattern of movement was soon contrasted with that occurring in mitral stenosis. Their findings were subsequently confirmed by other investigators, and ultrasound is now an accepted clinical means of investigation of patients with mitral valve disease. 39 , 40, 46, 47 Other investigators have since demonstrated the value of echocardiography in the diagnosis of pericardial effusion,ls hypertrophic obstructive cardiomyopathy,41 left atrial thrombus, left atrial myxoma,39 and tricuspid stenosisP In addition, left ventricular stroke volume and valvar regurgitation,19 left ventricular wall thickness,17 as well as the dimensions of both ventricles 36 and the left atrium,26 have been measured by this technique. ':'Physician, Cardiac Clinic, Groote Schuur Hospital; Senior Lecturer, Department of Medicine, University of Cape Town ':":'Paediatric Cardiologist, Groote Schuur Hospital and Red Cross War Memorial Children's Hospital; Lecturer, Departments of Medicine and Child Health, University of Cape Town tPhysician, Cardiac Clinic, Groote Schuur Hospital; Senior Lecturer, Department of Medicine, University of Cape Town tSenior Physician, and Director, Cardiopulmonary Unit, Groote Schuur Hospital; Associate Professor and Senior Lecturer, Department of Medicine, University of Cape Town

Pediatric Clinics of North America- Vol. 18, No.4, November 1971

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ELLIOT CHESLER, HYMIE S. JOFFE, WALTER BECK, AND VELVA SCHRIRE

In the field of congenital heart disease, where the pediatric cardiologist is frequently confronted with the need for detailed investigation of seriously ill patients who have complex abnormalities, the advantage of employing a supplementary atraumatic technique is apparent. Preliminary observations utilising echocardiography in this area have provided evidence of the rapid velocity of motion of the atrioventricular valves, resulting from increased blood flow associated with left to right shunts.42 Recent work, however, has demonstrated the potential for more extensive application of the technique. I , 4 The anatomical elucidation of the source of intracardiac echoes has clearly shown that the various cardiac chambers, the ventricular septum, the atrioventricular valves, as well as the aortic root and valve, can be identified ultrasonically. The reader is referred to the work of Gramiak et al. for the ultrasonic validation studies of cardiac anatomy using selective injections ofindocyanine green dye to produce intracardiac echoes. 20 In the light of these findings and the fact that echocardiography is relatively easy to perform in children, we have used ultrasound as a non-invasive means of elucidating the anatomy of various cardiac malformations. Patients are systematically examined for the presence of the ventricular septum, the number and function of the atrioventricular valves, and the relationship of the anterior mitral leaflet to the aortic root. The data so obtained is presented in this review, and in our experience has yielded valuable information, particularly where the angiographic interpretation of the pathologic anatomy has been in doubt.

PRINCIPLE AND APPARATUS Ultrasound refers to sound waves whose frequency lies above the audible range, that is, above 20,000 cycles per second. These waves have no harmful effects on body tissues. Traversing a homogeneous medium such as fluid, these waves travel in a straight line, but on impact with an interface between two media of differing densities they are reflected like light waves. In nonhomogeneous living tissues ultrasound waves are returned as echoes whenever they strike zones of differing acoustic impedance. Since ultrasound waves have a relatively constant transit time through most soft tissues, the time between transmission and reception of the signal allows measurements of the transducer-interface distance. The same principle is utilised in the sonar and as die systems for surface localisation of submarine depth. Most commercially available echocardiograph machines embody similar features; we have worked with a Smith-Kline Eskoline-20 instrument. Ultrasound waves are produced by mechanical vibration of a piezo electric (barium titanate) crystal stimulated by a high frequency alternating current. The crystal is encased in a 3/4 inch transducer. Since piezo electric crystal is also capable of converting ultrasound mechanical energy into electrical voltage, the transducer acts as a receiver as well, and returning echoes can be made to appear on an oscilloscopic screen. The apparatus transmits intermittent pulses of

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ECHOCARDIOGRAPHY

ultrasound at a rate of 1000 impulses per second and the crystal is free to receive echoes of each impulse before electrical stimulation generates the next pulse. Echoes may be displayed on an oscilloscopic screen in one of two modes (Fig. 1). In the A mode, the echoes are displayed as vertical signals on a calibrated horizontal baseline showing the transducer-interface distance; movement occurs in a horizontal direction. The A mode is valuable for visual scanning of the field to select echoes in the plane of the beam. On the B mode the signals on the oscilloscope are converted to sweep across the screen vertically; all horizontal movement is seen and recorded in wave form. The calibration scale of the A mode is represented by a series of dots on the B mode, recorded each half second vertically and spaced 1 cm. apart horizontally. One lead of the electrocardiogram may be included and the signal adjusted to appear on a desired portion of the tracing. Incorporated on the machine are controls such as "near-gain," "coarse gain," "depth compensation control," as well as controls for under-damping and over-damping. These enable the operator to select, localise, and amplify selected echoes prior to polaroid photography of the image on the B mode.

TECHNIQUE U sing sonic gel to make a tight airless contact with the skin, the transducer is placed on the chest in various positions, to be discussed more fully. The operator carefully positions the transducer while watching the A mode to identify the various signals. The controls are adjusted

A MODE

Figure 1. Diagrammatic representa· tion of A and B modes as seen on oscilloscope of echocardiograph. CW, chest wall; RVW, right ventricular wall; RVC, right ventricular cavity; S, septum; MVE, mitral valve echo; ECG, electrocardiogram; LVW, left ventricular wall.

BMODE

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ELLIOT CHESLER, HYMIE S. JOFFE, WALTER BECK, AND VELVA SCHRIRE

so that relevant echoes are correctly amplified in the desired field. The apparatus is then converted from A to B mode and a polaroid photograph taken of one full sweep across the screen. The photograph is available within 15 seconds. We have performed echocardiography in infants and children whose ages range from 48 hours upward. Usually sedation is unnecessary; occasionally we have used chloral hydrate or a cocktail consisting of promethazine, promazine, and pethidine where prolonged study has been necessary. The time taken for the study is variable. In instances where we have merely been interested in demonstrating the ventricular septal echo the examination has been completed in a few minutes. Longer periods have been spent attempting to obtain good quality photographs on the B mode, although the information had been clearly visualised on the oscilloscope screen in the A mode. The 3/4 inch transducer, which is of standard size and used for adults as well, has proved to be no handicap when used in the neonate; very little movement is required, however, and stability of the transducer is critical. In infants of less than 15 lb. in weight, the small chest is readily traversed by the ultrasonic beam and the machine has to be appropriately damped to avoid blurring of the echoes. In adults with large anteroposterior chest diameters or with muscular chest walls or emphysema, echocardiography may be technically very difficult. These problems do not arise in children and location of the intracardiac echoes is relatively easy. Once familiarity with the ultrasonic characteristics of the various structures has been gained, an electrocardiogram is usually not essential, and we do not include this routinely. Wherever possible, we have proceeded in a systematic fashion, moving from one intracardiac structure to the next, according to their known anatomical relationships, in the following manner. Location of the Mitral Valve The anterior leaflet of the mitral valve is located with the transducer placed in the left third to fifth intercostal space, pointing posteromedially (Fig. 2). In patients with mirror-image dextrocardia the corresponding position to the right of the sternum is used. When dextroversion (apex pointed to the right) is present, the mitral valve echo is located to the right of the usual position and has to be "searched" for by altering the transducer position. It is recognised by its posterior location and its characteristic "kick," moving anteriorly in diastole, floating back and reopening during atrial systole (Fig. 3). The various points on the mitral valve echo during the cardiac cycle are shown in Fig. 4A, according to the designation of Edler. 7 In early ventricular systole, the tracing moves sharply in a posterior direction (B to C). During the rest of ventricular systole, the mitral valve echo moves gradually anteriorly (C to D). In early diastole, the echo shows another abrupt anterior opening movement to the E point. There follows a steep backward movement to point E as the valve floats back towards the left atrium. In late diastole, when the left atrium contracts the valve reopens to another anterior peak point, A.

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Figure 2. Diagrammatic representation of a transverse section of the heart at the level of the aortic root to illustrate ultrasonic location of intracardiac structures by alteration of transducer (T) position. Positions 1,2, and 3 indicate location of mitral valve (MV), aortic root (Ao) and tricuspid valve (TV) respectively. Land R, left and right sides of chest; LA, left atrium; RA, right atrium; RV, right ventricle.

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Figure 3. Echocardiograms obtained in mitral valve recording position. A, Septal echo (sept). In B the septal echo is not recorded. RVW, right ventricular wall; RVO, right ventricular outflow tract; LVO, left ventricular outflow tract; MV, mitral valve echo; LAW, left atrial wall.

The left ventricular outflow tract lies between the anterior mitral leaflet and the left side of the ventricular septum (Fig. 2). Occasionally, in normal subjects this leaflet makes contact with the ventricular septum. Between the right side of the septum and the anteriorly situated right ventricular wall, which moves inwards during systole, is the echo free space of the right ventricular cavity. At its point of maximal diastolic (anterior) excursion, the anterior mitral leaflet is thus separated from the anterior right ventricular wall by the cavity of the right ventricle and the ventricular septum (Fig. 3). In normal patients, the E point is separated from the endocardial surface of the right ventricle by a distance of 1 to 2 cm. When right ventricular enlargement is present, as in atrial septal defect or complete transposition of the great vessels, the septum is located further back and the E point thus lies more posteriorly. Posterior to the mitral valve, the beam locates the left atrial wall

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ELLIOT CHESLER, HYMIE S. JOFFE, WALTER BECK, AND VELVA SCHRIRE

(recognised by its posterior movement in systole) or the left ventricular wall (recognised by its anterior movement in systole. 26 ) When there is mitral stenosis the most important deviation from normal is the change in velocity of the posterior movement of the anterior mitral leaflet following the E peak in diastole (Fig. 4B). Normally, the rate of this slope in adults varies from 85 to 200 mm. per sec., and we have found a similar range in children. In mitral stenosis the rate is reduced to speeds of 40 mm. per sec. The rate of mitral valve closure tends to decrease with increasing severity of stenosis and is a function of the duration of the positive pressure gradient between the left atrium and the left ventricle and the rate of filling of the left ventricle. 47

Aortic Root Slight medial and cephalic rotation of the transducer from the mitral valve recording position moves the ultrasonic beam up the outflow tract of the left ventricle (Figs. 2 and 5). The septal echo changes into

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Figure 4.

Echograms showing pattern of movement of anterior mitral leaflet echo (AM).

A, Normal, with sinus rhythm. B, Mitral stenosis with atrial fibrillation.

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Figure 5. Diagrammatic representation of technique for location of aortic root. POinting the transducer posteromedially, position 1, locates the anterior mitral leaflet (AM). Medial and cephalic rotation of the transducer, position 2, then locates the aortic root.

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that of the posterior margin of the aortic root. The aortic root echoes lie parallel and move together in the same direction (anteriorly in systole and posteriorly in diastole). Between the two signals of the aortic root, echoes of the aortic valve leaflets are frequently recorded (Fig. 6). The "mitral ring" echo exhibits a pattern of movement identical with that of the posterior margin of the aortic root and is recorded from the zone of fibrous attachment of the anterior mitralleafiet to the aortic root. The aortic root is centrally located (Fig. 2) with the left atrium situated posteriorly and the right ventricular outflow tract anteriorly.20-22.25

Mitral-Aortic Continuity Normally, the base of the anterior mitralleafiet is in fibrous continuity with the bases of the posterior and left cusps of the aortic valve. 23 The fact that it is possible to identify and record the mitral valve and the aortic root echoes in a continuous sweep by angulation of the transducer is a manifestation of the normal mitral-semilunar continuity. In its most posterior (closed) position the mitral valve echo is continuous with and at the same depth as the posterior margin of the aortic root.20-22 The same finding may be observed angiographically, and the assessment of mitralsemilunar continuity is of great importance in the elucidation of certain congenital malformations23 (Fig. 7). With few exceptions, the presence of mitral-semilunar discontinuity23 indicates the presence of double outlet right ventricle, a topic to be discussed later.

Tricuspid Valve In the normal adult, it is difficult to record a complete cycle of tricuspid valve motion, unless the right ventricle is enlarged. 27 In children, however, this may be more readily accomplished (Fig. 8). The tricuspid valve is located by angulating the transducer inferiorly and to the right from the aortic valve recording position (Fig. 2). Its pattern of movement is identical with that of the mitral valve but may be seen to occur later when both valves are occasionally recorded in the same tracing (Fig. 9). Its position lies anterior to that of the mitral valve echo and its E point frequently abuts against the fuzzy band of echoes of the right ventricular wall. Its systolic (closed) position lies at the same level as the anterior wall of the aortic root.

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A Figure 6. Echograms showing parallel signals of aortic root. In B, cusp echoes are demonstrated. RVO, right ventricular outflow tract.

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ELLIOT CHESLER, HYMIE S. JOFFE, WALTER BECK, AND VELVA SCHRIRE

Figure 7. A to C, Echograms illustrating mitral-aortic continuity. A and B are a composite recording of a sweep from the anterior mitral leaflet (AM) to the aorta. C demonstrates a sweep from the aorta to the anterior mitral leaflet. D, Left ventricular angiogram, lateral view, showing. closed anterior mitral leaflet. The echo grams and the angiogram demonstrate that, in its closed position, the anterior mitral valve leaflet and the posterior margin of the aorta form one straight line and are at the same depth .

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Figure 8. Echogram showing anterior position and pattern of movement of tricuspid valve (TV). RVW, right ventricular wall.

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Figure 9. Echogram from a boy aged 3 years with a ventricular septal defect, showing simultaneous recordings of tricuspid and mitral valves. A septal echo is not demonstrated.

Ventricular Septum This is frequently identified from the mitral valve recording position, but a specific attempt must be made to locate the septum, according to the technique of Popp et al. 36 The transducer is placed in the mitral valve recording position, but instead of pointing posteromedially toward the mitral valve, it is directed posterolaterally and slightly inferiorly, away from the mitral valve echo and toward the posterior wall of the left ventricle. In this position, by increasing sensitivity in the near-field, the septal echo may be recorded and it is often possible to demonstrate the left and right interfaces of the septum with an echo free space between (Fig. 10). Normally, the septum moves sharply posteriorly during ventricular systole and anteriorly during diastole. Measurements of normal ventricular dimensions have not, to our knowledge, been made in the various age groups, but Popp et al. 36 found that in adults the mean right ventricular and left ventricular dimensions were 1.5 and 4.5 cm. respectively, a ratio of 1i3. The septal echo may be confused with that of the mitral ring when right ventricular enlargement displaces the septum posteriorly. The pattern of movement dis-

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] RVe Figure 10. Echogram obtained from an infant aged 3 months with tetralogy of Faliot, illustrating septal echo and dimensions of right (RVC) and left (LVC) ventricular cavities.

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ELLIOT CHESLER, HYMIE S. JOFFE, WALTER BECK, AND VELVA SCHRIRE

tinguishes the two structures, the septum moving posteriorly and the mitral ring moving anteriorly during systole. The pulmonary valve is never recorded from the above transducer positions in a normal individual. This is because the pulmonary valve is situated too high, being separated from the tricuspid valve by the crista supr~ventricu1aris, and thus not being in the path of the transducer beam. The pulmonary valve cannot be recorded from a high left parasternal position either, because the ultrasonic beam is blocked by interposed lung tissue. 2o The same phenomenon pertains to the aortic valve in cases of complete transposition of the great vessels when the aorta arises from the right ventricle. While the application of this technique in children is usually easy, the examination is not casual and artefacts are possible when recordings are made in random fashion. Figure 9 illustrates simultaneous recordings of the mitral and tricuspid valves obtained fortuitously in a child with a small ventricular septal defect; an intervening septal echo was not recorded. Also, overdamping of tracings may obscure septal echoes (Fig. 3B), and underdamping may fuse the septal echoes with those of the right ventricular wall. The absence of septal echoes may erroneously suggest the diagnosis of single ventricle and illustrates the need for careful systemic examination. In summary, the data obtained by the methods described supplies information as to the number and function of the atrioventricular valves, establishes the presence and relative sizes of the two ventricles, as well as the relationship between the anterior mitral leaflet and the most posteriorly placed semilunar valve ring.

DIAG:NOSIS OF CONGENITAL HEART DISEASE The pathological alterations identified by echocardiography in the field of congenital heart disease may be described as follows: Single functioning ventricle True anatomical single (common) ventricle Functional single ventricle Hypoplastic right heart syndrome Hypoplastic left heart syndrome Two functioning ventricles Double outlet right ventricle Congenital mitral valve disease Atrial septal defect Aortic stenosis

SINGLE FUNCTIONING VENTRICLE

Among congenital cardiac malformations, certain entities characterised by severe hypoplasia of the right or the left sides of the heart behave

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functionally like a true single ventricle and exhibit similar echocardiographic abnormalities. True Single Ventricle By definition, a single (common) ventricle is one which receives both the tricuspid and mitral valves or a common atrioventricular valve. IS. 24. 43 Because the ventricular septum is absent, there is frequently continuity between the basal aspects of the septal leaflet of the tricuspid valve and the anterior leaflet of the mitral valve, even though they arise from two separate valve rings. IS A single large atrioventricular ring with one large anterior and a smaller posterior leaflet may be present, particularly when the condition is associated with a common atrium, as in the polysplenia or asplenia syndromes.37 Uncommonly, the mitral and tricuspid valves are completely separated by muscular tissue1s (Fig. 11). Von Praagh and colleagues43 have differentiated four types of single ventricle on the basis of the ventricular morphology. From the diagnostic point of view, however, only two types may be recognised by investigation: 24 (1) Single ventricle without a rudimentary chamber (representing the infundibulum or conus of the right ventricle and an absent inflow or sinus portion of the right ventricle); and (2) single ventricle with a rudimentary chamber. The great vessels may be normally related but are usually transposed. In the transposed situation the aorta arises from a rudimentary chamber (when present) either anteriorly and to the left (L-transposition) or anteriorly and to the right (D-transposition). The malformation is frequently complicated by the presence of pulmonary stenosis. The presence of single ventricle may be suspected on the basis of

Figure 11. Diagrams illustrating the anatomy of atrioventricular valves in single ventricle. A, ConjOined septal tricuspid (ST) and anterior mitralleafiets (AM) attached to base of posteriorly situated pulmonary artery (PA). B, Common atrioventricular valve (CV) associated with common atrium. C, Two separate atrioventricular valves. RC, rudimentary chamber. (After Elliot, L. P., et al.: Brit. Heart J. 26:289,1964.)

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ELLIOT CHESLER, HYMIE S. JOFFE, WALTER BECK, AND VELVA SCHRIRE

clinical, radiological, and electrocardiographic features, but conditions such as tetralogy of Fallot, tricuspid atresia, corrected and complete transposition of the great vessels, and ventricular septal defect have to be entertained in the differential diagnosis. The diagnosis must be confirmed by cardiac catheterisation, which demonstrates evidence of mixing of systemic venous and pulmonary venous blood resulting in close approximation of systemic arterial and pulmonary arterial oxygen saturations. High quality selective biplane angiography demonstrates both atrioventricular valves or a single atrioventricular valve entering the common ventricle, absence of a ventricular septum, a rudimentary chamber when present, and also defines the relationships of the great vessels. We have performed echocardiography on 14 patients in whom the diagnosis of single ventricle was made on the basis of haemodynamic and selective angiographic evidence. The patients' ages ranged from 30 months to 24 years. The examinations were conducted in the manner described, except in 2 patients where dextroversion was present, when the transducer was placed to the right of the sternum. In 11 patients a single leaflet and no ventricular septum was found. The systolic (closed) position of this leaflet was situated well posteriorly but in its diastolic (open) position the leaflet moved excessively far anteriorly, almost abutting against the anterior ventricular wall (Fig. 12). This pattern of movement should not be confused with that of the anterior mitral leaflet of the normal heart because here the range of anterior movement is restricted by the ventricular septum and the cavity of the right ventricle anterior to it (Fig. 3). The detection of abnormal anterior movement should raise suspicion that a single ventricle may be present, and a careful search for the septal echo should be made. In these patients with single ventricle where a single leaflet was found, echocardiography cannot distinguish between the anterior component of a common atrioventricular valve with a single atrioventricular ring, or the conjoined septal tricuspid and anterior mitral leaflets, where two atrioventricular rings are present. From a functional point of

+-sv

Figure 12. A, Cineangiogram from a patient with single ventricle, common atrium, and asplenia; apex points to right (dextroversion). A large sail-like anterior leaflet of single valve (SV) is shown. B, Echogram showing single valve (SV) from such a case; this valve exhibits excessive anterior movement because a single ventricular cavity is present.

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ECHOCARDIOGRAPHY

view, both anomalies could produce an echo of a single anteriorly moving leaflet (Fig. llA and B). The posterior leaflet of a common valve or the posterior leaflets of two separate valves are not recorded for the same reason as the posterior leaflet of the normal mitral valve is rarely recorded - it lies too far posteriorly and moves away from, and not toward the transducer. In 3 patients, 2 valve leaflets were recorded at different depths moving in the same direction. In 1 of these both leaflets were identified simultaneously with the transducer held stationary in the left third interspace (Fig. 13). In the other 2, the 2 leaflets were located separated by variation of the transducer position (Fig. 14). A ventricular septum could not be identified between the anterior and posterior leaflets in

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Figure 13. Echogram in sin· gle ventricle with two separate atrioventricular valves, recorded simultaneously.

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Figure 14. Echograms in single ventricle showing (A) posteriorly located mitral valve (MV) and (B) anterior tricuspid valve (TV) and mitral ring (MR) .

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ELLIOT CHESLER, HYMIE S. JOFFE, WALTER BECK, AND VELVA SCHRIRE

either case. In these patients the echocardiographic findings suggested the less common variety of single ventricle where both atrioventricular valves are completely separated by muscular tissue17 (Fig. IlC). Although mitral-semilunar valve continuity may be present in single ventricle (Fig. lOA), we have not routinely examined for this ultrasonically, largely because its therapeutic implications are of importance only when two ventricles are present. Differential Diagnosis. The most difficult lesion to differentiate from single ventricle with L-transposition of the great vessels is corrected transposition with a large ventricular septal defect, since the electrocardiogram, haemodynamic data, and alignment of the great vessels may be identical in both conditions. This difficulty is compounded when the rudimentary chamber of the single ventricle is large. The angiographic clue is the demonstration of the fact that an atrioventricular valve does not enter the rudimentary chamber of the single ventricle. Even in complete transposition of the great vessels with the aorta in the D position the diagnosis of single ventricle should be entertained. Angiographic visualisation of the ventricular septum, the identification of the atrioventricular valves, and the ventricular morphology are thus crucial whenever the great vessels are transposed, but this is not always easily accomplished and the echocardiogram may provide considerable help. In corrected transposition of the great vessels there is transposition and inversion of the great vessels and inversion of the ventricles while the venous connections are normal. The right atrium connects via a mitral valve to the anatomical left ventricle on the right side, which then gives rise to the pulmonary trunk, arising posteriorly and to the right of the aorta; the mitral valve is continuous with the base of the pulmonary trunk. Similarly, the left atrium connects via a tricuspid valve to an anatomical right ventricle on the left side, from which the aorta arises anteriorly and to the left of the pulmonary trunk. The transposed great vessels usually lie in the L-position. The plane of the ventricular septum is rotated through 900 so that it runs from back to front and slightly to the right. s • IO Frequently the apex of the heart points to the right (dextroversion) or is centrally situated (mesoversion). Rarely, corrected transposition exists without associated abnormalities, in which case the circulation is normal. The vast majority of cases have associated lesions such as atrial septal defect, patent ductus arteriosus, and coarctation of the aorta, but particularly ventricular septal defect and pulmonary stenosis. lo The clinical picture may be very similar to that of single ventricle. Definitive diagnosis is made at cardiac catheterisation, the most helpful tool being selective angiography. Because of the almost sagittal alignment of the ventricular septum, the side-by-side relationship of the ventricles, and the frequent presence of associated dextroversion, the echocardiographic technique has to be modified to locate the septum and atrioventricular valves. Figure 15 illustrates the findings in a boy of 6 years with corrected transposition, ventricular septal defect and sub-aortic stenosis. In Figure l5A the transducer is held in the third left interspace directed posteriorly and

1177

ECHOCARDIOGRAPHY

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Figure 15. Echogram in corrected transposition of the great vessels (see text).

locates the tricuspid valve of the left-sided systemic, but anatomical right ventricle. Altering the transducer position to point progressively posteromedially, locates the double echo of the ventricular septum with tricuspid valve echo less well in focus (Fig. 15B and C). By rotating the transducer even further medially the mitral ring of the right-sided venous (anatomical left) ventricle is located (Fig. 15D). In two other cases of corrected transposition, we have encountered similar findings. In one, we were able to detect mitral-pulmonary continuity in the venous ventricle by placing the transducer to the right of the sternum, directly over the venous ventricle. In cases of complete transposition of the great vessels we have found that echocardiography performed in the usual manner readily indicates both the mitral and tricuspid valves as well as the ventricular septum. This is because the ventricular anatomy is normally orientated, only the great vessels being transposed. The aorta originates from the right ventricle and the pulmonary artery from the left ventricle, and instead of there being mitral-aortic continuity, there is mitral-pulmonary continuity.l0-23 Figure 16 illustrates the findings in an infant of 3 months. In Fig. 16A the echo of the posteriorly located mitral valve is demonstrated. In Fig. 16B, the ventricular septum and the base of the tricuspid valve are shown, and in Fig. 16C, the mitral ring and the opening movement of the tricuspid valve are depicted. As discussed later in the section dealing

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ELLIOT CHESLER, HYMIE S. JOFFE, WALTER BECK, AND VELVA SCHRIRE

Figure 16.

Echogram in complete transposition of the great vessels (see text).

with double outlet right ventricle, we have detected mitral-pulmonary continuity in all 5 cases of complete transposition of the great vessels which we have investigated. The echocardiographic findings in mitralaortic and mitral-pulmonary continuity are identical.

Functional Single Ventricle HYPOPLASIA OF THE RIGHT HEART. We have encountered 11 patients with severe hypoplasia of the right heart resulting from tricuspid atresia. In this condition there is no tricuspid valvular tissue and the mitral valve is the only atrioventricular valve. When pulmonary stenosis or atresia is also present, the pulmonary artery arises from a hypoplastic basal infundibular chamber. The sinus (or inflow) portion of the right ventricle is markedly hypoplastic. In tricuspid atresia without pulmonary stenosis there is usually transposition of the great vessels with increased pulmonary blood flow, and the right ventricle may be well developed. 10 When there is severe obstruction to pulmonary blood flow, the anatomy and haemodynamics are similar to that of single ventricle with pulmonary stenosis, a rudimentary chamber and one atrioventricular valve. All our patients with tricuspid atresia have had severe obstruction to pulmonary blood flow; their ages ranged from 1 month to 11 years. Angiocardiography in these patients demonstrated virtual absence of the sinus portion of the right ventricle. Echocardiography in these patients demonstrated absence of a septal echo and a single atrioventricular valve leaflet. This leaflet moved abnormally far anteriorly, in sharp contrast to that of a normal anterior mitral leaflet, because of hypoplasia of the right ventricular cavity (Fig. 17).

Hypoplasia of the right ventricle may also occur with a patent but hypoplastic tricuspid valve, usually associated with an atrial32 but also with a ventricular septal defect. 3 A minute right ventricular cavity is also associated with pulmonary atresia with intact ventricular septum, although a well-developed right ventricular cavity may be present especially when the tricuspid valve is incompetent. 14 We have not had the opportunity to study these other malformations characterised by severe right ventricular hypoplasia but anticipate on the basis of the pathologic

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Figure 17. A, Diagram of anatomy of tricuspid atresia with severe right ventricular hypoplasia. B, Echogram of such a case showing marked anterior movement of the mitral valve (AM). RVI, right ventricular infundibulum.

anatomy that ultrasound will yield similar findings to those found in tricuspid atresia when the right ventricular hypoplasia is severe. When pulmonary atresia is associated with an intact ventricular septum, the size of the right ventricular cavity determines the nature of surgical therapy. Where the right ventricle is of good size, pulmonary valvotomy is indicated, whereas palliative surgery (atrial septostomy and Waterston's shunt) is indicated in the presence of a hypoplastic right ventricle. The size of the right ventricular cavity may be very difficult to assess angiographically particularly when deep myocardial sinusoids are present. Estimation of right ventricular dimensiori ultrasonically may provide valuable information under these circumstances and assist in determination of the form of surgical treatment. HYPOPLASIA OF THE LEFT HEART. This complex of malformations in its most severe form consists of a slit-like left ventricular cavity, atresia of the aortic or mitral valves, or both, and severe hypoplasia of the ascending aorta. 16 ,33 The right ventricle functions as a single ventricle and supplies not only the pulmonary circuit but also the systemic circuit via a patent ductus arteriosus (Fig. 18). The ascending aorta and coronary arteries are supplied in retrograde fashion, provided that severe preductal coarctation of the aorta is absent. In less severe forms of this syndrome the mitral and aortic valves may be hypoplastic rather than atretic, and the left ventricular cavity and the ascending aorta may be more normal in size.33 The hypoplastic left heart syndrome is a frequent cause of death in the first week of life. Infants with this syndrome may appear normal at birth. Usually there is a rapid onset of tachypnoea with variable degrees of cyanosis and frank congestive cardiac failure. A striking physical sign is the poor quality of the peripheral pulses, which are usually weak in all four extremities. The pulses may even be stronger in the femorals - socalled "reversed coarctation" -if severe preductal coarctation of the aorta is also presenU' 30

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Figure 18. Diagrammatic representation of mitral atresia, ventricular septal defect, and severe hypoplasia of the left ventricle and ascending aorta. The right ventricle supplies the systemic and pulmonary circuits. PT, pulmonary trunk; PDA, patent ductus arteriosus.

We have employed echocardiography in the study of one patient with gross hypoplasia of the left heart. This infant died at the age of 4 days, 1 day following cardiac catheterisation and angiography. Necropsy revealed polysplenia, dextroversion, and gross hypoplasia of the left ventricle, mitral and aortic valves, and ascending aorta. The right ventricle was markedly enlarged and formed most of the cardiac bulk. The pulmonary artery was enlarged and supplied the descending aorta via a patent ductus arteriosus; severe preductal coarctation of the aorta was also present. Echocardiography in this patient revealed a single atrioventricular valve moving into diastolic apposition with the anterior ventricular wall, and a ventricular septum could not be identified (Fig. 19). By way of contrast, the findings in an infant of 8 days are described. This patient presented in severe congestive cardiac failure with poor peripheral pulses. Emergency cardiac catheterisation revealed preductal coarctation of the aorta, patent ductus arteriosus, and a hypoplastic ascending aorta. A small left ventricular cavity was identified angiographically. The child died 1112 hours after cardiac catheterisation. Echocardiography readily demonstrated a normal tricuspid valve (Fig. 20A). Repeated alteration of the transducer position failed to locate the mitral valve echo but did identify the ventricular septum (Fig. 20B). The position of the septum indicated that the right ventricular cavity was approximately three times the diameter of the left ventricular cavity, features which correlated well with the angiographic and postmortem findings. Necropsy demonstrated the presence of severe preductal coarctation and tubular hypoplasia of the aortic arch.

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Figure 19. Echogram from neonate with hypoplastic left heart syndrome. The tricuspid valve was the only valve demonstrated.

_RVW

+-RVW

-TV

1

RVe

_SEPT

] LVC

Figure 20. Echograms from neonate with milder variety of hypoplasia of left heart syndrome demonstrating (A) the tricuspid valve and (B) the ventricular septum (sept). and the relative sizes of the two ventricles.

Although the mitral valve leaflets were normal, the mitral ring and the left ventricular cavity were hypoplastic and the right ventricular chamber formed most of the cardiac bulk.

Clinical Value When echocardiography elicits absence of the ventricular septum and a single anteriorly moving atrioventricular valve, or occasionally two atrioventricular valves not separated by a ventricular septum, the anatomic counterpart is a true single ventricle or a functional single ventricle resulting from severe hypoplasia of the left or right sides of the heart. The clinical, electrocardiographic, and radiologic diagnosis of the cause of heart failure in infancy may be difficult. The differential diag-

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ELLIOT CHESLER, HYMIE S. JOFFE, WALTER BECK, AND VELVA SCHRIRE

nosis of hypoplastic left heart syndrome in the neonate includes coarctation of the aorta, contracted endocardial fibroelastosis, myocardial ischaemia (aberrant origin of the left coronary artery), large left to right shunts from ventricular septal defect, patent ductus arteriosus or truncus arteriosus, infradiaphragmatic total anomalous pulmonary venous drainage, endocardial cushion defect, and viral myocarditis. The hypoplastic right heart syndrome usually presents with more marked cyanosis and must be differentiated from transposition of the great vessels, pulmonary stenosis and atresia with intact ventricular septum, and tetralogy of Fallot. The ultrasonic recognition of a true or functional single ventricle narrows the differential diagnosis considerably and excludes all the abovementioned conditions in which two atrioventricular valves and two ventricles are present. In those patients in whom transposition of the great vessels is recognised at cardiac catheterisation, the question of single ventricle must always arise. Echocardiography may be of particular assistance by demonstrating the presence of a ventricular septum when the angiographic findings are inconclusive.

Two

FUNCTIONING VENTRICLES

When two ventricles, two atrioventricular valves, and a ventricular septum have been identified, we have found echocardiography to be of additional use in the following circumstances: Diagnosis of Double Outlet Right Ventricle - Echocardiographic Detection of Mitral-Semilunar Valve Discontinuity In the investigation of patients with congenital heart disease the presence of a large ventricular septal defect subjacent to the aorta or pulmonary artery may obscure the angiographic recognition of the site of origin of the great vessels. 24 Malformations such as tetralogy of Fallot, transposition of the great vessels with overriding of the pulmonary trunk, even an infracristal ventricular septal defect, may be difficult to distinguish both clinically and angiographically from double outlet right ventricle45 (origin of both great vessels from the right ventricle34 ). The preoperative diagnosis of double outlet right ventricle is important, since this malformation requires specific methods of repair; routine closure of the ventricular septal defect in an undiagnosed case will have disastrous results. In double outlet right ventricle the only outlet for the left ventricle is via a ventricular septal defect, since both the aorta and the pulmonary artery originate from the right ventricle. The aortic and pulmonary valves tend to lie at the same level because both valves have underlying conus tissue. The anterior mitral leaflet is separated by muscular tissue from the root of the aorta, in contrast to the normal heart where there is fibrous union between the anterior mitral leaflet and the left and noncoronary cusps of the aortic valve. In corrected and complete transposition of the great vessels, the anterior mitral leaflet is continuous with the pulmonary artery because it arises from the anatomical left ventricle.

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With rare exceptions, the presence of mitral-semilunar valve discontinuity is diagnostic of double outlet right ventricle. Neufeld et al. have classified double outlet right ventricle into two types, depending upon the position of the ventricular septal defect. 34 In Type 1, the ventricular septal defect is situated postero-inferior to the crista supraventricularis and tends to lie below the aortic valve but well separated from the pulmonary valve, so that there may be streaming of left ventricular blood into the aorta. The clinical picture in Type 1 in the absence of pulmonary stenosis resembles that of a large ventricular septal defect of the usual variety as the cyanosis may be minimal. Clinical examination, routine chest roentgenograms, and the electrocardiogram may offer few clues to the correct diagnosis. When double outlet right ventricle Type 1 is complicated by the presence of infundibular pulmonary stenosis there is the tendency for streaming of right ventricular blood into the aorta and the picture may be similar to that of tetralogy of Fallot or transposition with pulmonary stenosis. Patients present with cyanosis, clubbing and an ejection systolic murmur and single second heart sound on auscultation: Roentgenograms of the chest commonly show a dilated ascending aorta, concave pulmonary artery segment, and oligaemic lung fields. In Type 2 double outlet right ventricle (Taussig-Bing anomaly44) the ventricular septal defect lies anterosuperior to the crista supraventricularis immediately subjacent to the pulmonary valve. Here, left ventricular blood streams into the pulmonary artery, and right ventricular blood into the aorta, resulting in intense cyanosis. The clinical signs are those of transposition of the great vessels with a ventricular septal defect and pulmonary hypertension. Roentgenograms of the chest show cardiomegaly, usually a prominent pulmonary artery, and considerable pulmonary plethora. The electrocardiogram usually shows right axis deviation and right ventricular hypertrophy. The diagnosis of double outlet right ventricle, and the exclusion of the aforementioned conditions which may mimic it, must be made at cardiac catheterisation. Selective angiography demonstrates the aorta and the pulmonary artery arising from the right ventricle, with their semilunar valves at nearly the same level because of the bilateral conus. The relative positions of the great vessels are variable; they may be side-by-side, or the aorta may be to the front and to the right, or in front of and to the left of the pulmonary artery. The diagnostic angiographic feature of the malformation is mitral-semilunar valve discontinuity, which is best demonstrated by selective left ventricular angiography performed in the lateral view23 (Fig. 22C). In contrast to double outlet right ventricle, fibrous continuity of the anterior mitral leaflet with the aorta may be observed angiographically in various other malformations when the great vessels are normally related, or with the pulmonary artery when there is complete or corrected transposition of the great vessels. In its closed position (in systole) the anterior mitral leaflet and posterior margin of the attached great vessels form one straight line (Fig. 7D). In diastole, the anterior mitral leaflet swings forward as the valve opens. The same phenomenon

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ELLIOT CHESLER, HYMIE S. JOFFE, WALTER BECK, AND VELVA SCHRIRE

has been clearly demonstrated ultrasonically by the work of Gramiak et al. in their studies on patients with aortic valve disease2" 22 (Fig. 7A toe). Utilising this knowledge, we have studied patients with a variety of congenital malformations by echocardiography and have detected the normal mitral-semilunar valve continuity in patients with tetralogy of Fallot, pulmonary atresia, complete and corrected transposition of the great vessels, and tricuspid atresia with transposed great vessels. U sing the technique already described for the location of the aortic root, we have found that the recognition of mitral-seInilunar valve discontinuity by echocardiography varies according to the anatomical disposition of the great vessels. DOUBLE OUTLET RIGHT VENTRICLE WITH SIDE-TO-SIDE RELATIONSHIP OF THE GREAT VESSELS. Following the identification of the mitral valve echo, the point of most posterior excursion of the anterior mitral leaflet is carefully noted on the A mode. The transducer is then rotated medially and cephalad until the aortic root is located. The point of its most posterior excursion is carefully noted and compared with the former measurement. Polaroid photographs are then taken of sweeps of the transducer from the aorta to the mitral valve and vice versa. Any disparity in depth between the position of the anterior mitral leaflet and the aortic root is then measured in centimeters off the graduated scale. These measurements may be compared with siInilar measurements made from the angiograms after appropriate allowance is made for the degree of magnification. In contrast to the normal, in the 6 patients with double outlet right ventricle whom we have studied, the most posterior (systolic) position of the mitral valve echo lay deeper to the posterior margin of the aortic valve echo (Fig. 21). The degree of separation ranged from 1 to 1.8 cm. and these measurements correlated well with our angiographic findings4 and described pathologic measurements. 44 DOUBLE OUTLET RIGHT VENTRICLE WITH TRANSPOSED GREAT VESSELS. In our two patients studied with this type of relationship the pulmonary valve was slightly lower and to the left of the aortic valve. In both cases the ventricular septal defect was sub-pulmonary and there was no pulmonary stenosis (Neufeld Type 11). These patients presented with cyanosis, pulmonary hypertension, and pulmonary plethora, and mimicked complete transposition with a large ventricular septal defect. The echocardiographic findings differed from Group A and are illustrated in Figure 22. Following identification of the mitral valve echo, slight cephalic rotation of the transducer permitted simultaneous recordings of both the mitral and the adjacent pulmonary artery echoes in the same plane but at different depths. The echo of the posterior cusp of the pulmonary valve was recorded in both cases enclosed between the undulating signals of the root of the pulmonary artery. Repeated alteration of the transducer failed to demonstrate any connection between the anterior mitral leaflet and a semilunar valve.

Clinical Value Identification of mitral-semilunar valve relationships by selective angiography may be difficult Even with high quality technique, particu-

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D t-----f-.2

D 0

o

D D

o

Figure 21. A, Echogram in double outlet right ventricle, side to side relationship of great vessels. The arrow points to the posterior margin of the aorta and the closed position of the mitral valve (MV). The distance between the arrowheads indicates the degree of mitralsemilunar valve discontinuity. B, Diagram illustrating movement of ultrasonic beam from the anterior mitral leaflet (AM), position 1, to anteriorly situated aorta, position 2.

o o o o o

D

D

Figure 22. Double outlet right ventricle, transposed great vessels. A, Diagram showing recording position for anterior mitral leaflet (AM), position 1, and simultaneous recording of pulmonary artery and AML at different depths, position 2. B, Echogram showing mitral valve echo (MV) separate from adjacent pulmonary artery. PA, pulmonary artery; RVO, right ventricular outflow tract. C, Right ventricular angiogram, lateral view, showing both aorta and pulmonary artery originating from right ventricle. Anterior mitral leaflet (AM) discontinuous with both great vessels.

lady when malposition or rotation of the heart is present. It is clear that ultrasound cannot establish which great vessel is continuous with the mitral valve but its value lies in the fact that when the normal mitralsemilunar valve continuity is established, double outlet right ventricle may be excluded.

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ELLIOT CHESLER, HYMIE S. JOFFE, WALTER BECK, AND VELVA SCHRIRE

In tetralogy of Fallot the aorta may override the ventricular septum by more than 50 per cent but mitral-semilunar valve continuity is still maintained. It is in the distinction of this type of tetralogy, and of transposition with pulmonary stenosis, from double outlet right ventricle with pulmonary stenosis, that we have found ultrasound to be most useful. It is equally helpful in distinguishing the Taussig-Bing anomaly with transposed great vessels from complete transposition with overriding of the pulmonary artery where the angiographic differentiation may be extremely difficult. The nature of mitral-semilunar valve relationships is important therapeutically and determines the manner of surgical repair. In transposition of the great vessels with overriding of the pulmonary artery where there is mitral-pulmonary continuity,lO closure of the ventricular septal defect with the Mustard operation is indicated. When the TaussigBing malformation is present, there is mitral-pulmonary discontinuity and it is necessary to construct a tunnel from the left ventricle to the pulmonary artery and then to carry out the Mustard procedure. 29

Congenital Mitral Valve Disease We have not had the opportunity to study a patiept with one of the varieties of congenital mitral stenosis but have noted the typical findings in several African children aged 4 to 6 years with rheumatic mitral stenosis. Congenital mitral stenosis may be a manifestation of valve thickening and commissural fusion or a parachute mitral valve. 28 • 38 It may be reasonably anticipated that these deformed rigid valves will show the same findings as in rheumatic mitral stenosis. Utian and co-workers42 have shown that in left to right shunts resulting from ventricular septal defect or patent ductus arteriosus the diastolic velocity of anterior mitral leaflet motion is rapid. (Similar findings were found related to the tricuspid valve in cases of left to right shunt resulting from atrial septal defect). The increased velocity is presumably related to the high rate of mitral flow and the velocity returns to normal when the ductus or the ventricular septal defect is closed. The ability to assess mitral valve function by echocardiography suggests the potential for application of this test to the assessment of the significance of mid-diastolic murmurs in the presence of a left to right shunt where the significance of mitral gradients assessed from wedged pulmonary artery and left ventricular pressures may be difficult to interpret. The demonstration of a normal or increased velocity of closing movement of the anterior mitral leaflet would exclude the presence of those varieties of congenital mitral stenosis where there is a rigid valve mechanism. When a true pressure gradient is demonstrated by direct left atrial and left ventricular pressures, echocardiographic demonstration of normal mitral valve closing velocity would suggest the presence of a supra-valvular stenosing ring of the left atrium, which may be associated with a ventricular septal defect. 31 Similarly, in the investigation of young patients with evidence of pulmonary venous hypertension, a normal mitral valve echo would point

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to other conditions such as obstructive total anomalous pulmonary venous drainage, congenital stenosis of the pulmonary veins, cor triatriatum, or a supravalvular stenosing ring of the left atrium. 3! Atrial Septal Defect Diamond et al. have studied the use of echocardiography in patients with atrial septal defect. 6 The echo grams were evaluated for right ventricular dimension and motion of the ventricular septum. In those patients with normal pulmonary vascular resistance the size of the right ventricular dimension correlated with the size of the shunt. In 37 of their 39 patients, there was abnormal septal motion and only patients with tricuspid regurgitation from other causes had similar echocardiographic findings. This must therefore indicate diastolic overload of the right ventricle. If tricuspid incompetence can be excluded (generally an easy matter), echocardiography should be very useful in the evaluation of patients with atrial septal defect. The abnormal septal motion has previously been described by Popp et al,36 and may consist of a complete reversal of the normal movement, i.e., left septal echo moved slightly posteriorly after the P wave and then anteriorly after the QRS complex, reaching maximal excursions near the peak of the T wave. The echo then moved posteriorly with a notch or plateau in early diastole at the time of mitral valve opening. This pattern is very similar to that exhibited by the left ventricular wall echo. A less frequent pattern observed by these authors differed from the normal mainly during systole. After the QRS complex there was little if any motion and there was a plateau between the QRS complex and T wave. Between the T and P waves there were commonly oscillations of low amplitude towards and away from the transducer. As pointed out by these authors, to elicit these patterns of abnormal septal motion it is important to note that the transducer must be kept away from the mitral valve echo; otherwise, changes such as these may be found in normal subjects. 36 Aortic Stenosis VALVE STENOSIS. Recently, the aortic valve has received considerable attention by echocardiographers. While the aortic root is relatively easy to demonstrate ultrasonically, it is more difficult to obtain clear records of the movements of the leaflets and to diagnose aortic stenosis on the basis of their abnormal opening and closing rates or amplitudes. However, normal cusps reflect fewer echoes than the aortic wall. Patients with aortic stenosis and calcification have been found to have many diastolic echoes with cusp echo intensity greater than that of the aortic root. The actual valve orifice cannot be calculated from the echogram because the appearance in systole is usually obscured by the abnormal echoes arising from the immobile edges of thickened CUSpS.21. 25 Nevertheless, in patients with an aortic ejection murmur these findings would suggest the presence of a congenital bicuspid aortic valve rather than subaortic or supravalvular stenosis. MEMBRANOUS SUBAORTIC STENOSIS. Utian et al,42 have reported their findings in 2 patients with this condition. Motion of the mem-

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branous diaphragm in the left ventricular outflow tract was identified in both the direct and photographic ultrasonic tracings in the presence of normal mitral valve motion. Echoes originating from the membrane were thin and of low amplitude in contrast to the thick echoes commonly seen in patients with deformed mitral valves with similar low amplitude of movement. We have studied 2 proven examples of this condition but have been unable to identify the subaortic diaphragm. HYPERTROPHIC OBSTRUCTIVE CARDIOMYOPATHY. Shah et alY have described the diagnostic ultrasonic findings in this condition. Asymmetrical hypertrophy of the ventricular septum results in abnormal rotation of the mitral valve apparatus with systolic ballooning of the anterior leaflet producing systolic obstruction of the left ventricular outflow tract. Abnormal sharp systolic anterior movement of the mitral leaflet is readily elicited ultrasonically and is virtually diagnostic of this condition. Obstructive cardiomyopathy is uncommon in the pediatric age group but diagnostic suspicion of this condition may arise in the interpretation of a "functional" systolic murmur at the third left interspace in children, particularly when the murmur is of the loud vibratory type and associated with a high cardiac output. The demonstration of normal systolic position of the anterior mitral leaflet is a strong point against the diagnosis of obstructive cardiomyopathy.

SUMMARY We have reviewed the use of echocardiography in the diagnosis of congenital heart disease. Although our experience in this field is relatively new we have been attracted to the use of this technique because of its complete safety, portability, and, most important, the fact that it is noninvasive and suitable for use in seriously ill patients, including neonates. The ability of this technique to identify both the right and left ventricular cavities, the ventricular septum, and the presence and motion of both atrioventricular valves as well as mitral-semilunar valve relationships provides a great deal of useful information when conditions such as single ventricle, the hypoplastic left and right heart syndromes, double outlet right ventricle, congenital mitral and aortic valve disease, as well as atrial septal defect, are being investigated. Used in conjunction with the clinical, radiologic, and electrocardiographic data we have found the method to be a helpful and rapid auxiliary technique prior to cardiac catheterisation. The test has proved to be of value on those occasions when angiograms have not been of the highest quality and doubt has existed about the presence of a ventricular septum, a structure which is relatively easy to identify ultrasonically. Further experience with the technique in these and other malformations, such as Ebstein's disease of the tricuspid valve, may provide additional information and may also lead to more routine use of this diagnostic tool.

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ACKNOWLEDGMENTS

We wish to thank the Medical Superintendent of Groote Schuur Hospital, Dr. J. G. Burger, for permission to publish our findings; our thanks are due to Mrs. B. Arenson and Miss S. Joseph for help with the illustrations, and we particularly wish to acknowledge the helpful correspondence with Dr. Jesse E. Edwards relating to congenital cardiac malformations. Our thanks are also due to the Cape Town City Council, the South African Medical Research Council, and the Harry Crossley Foundation for financial support.

ADDENDUM

Since preparation of this manuscript, electrocardiographic abnormalities in Ebstein's disease have been described by Lundstrom and Edler. sl •

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22. Gramiak, R., and Shah, P. M.: Echocardiography of the aortic root. Invest. Radiol., 3:356,1968. 23. Hallerman, F. J., Kincaid, O. W., Ritter, D. G., and Titus, J. L.: Mitral-semilunar valve relationships in the angiography of cardiac malformations. Radiology, 94 :63, 1968. 24. Hallerman, F. J., Davis, G. D., Ritter, D. G., and Kincaid, O. W.: Roentgenographic features of common ventricle. Radiology, 87 :409, 1963. 25. Hernberg, J., Weiss, B., and Keegan, A.: The ultrasonic recording of aortic valve motion. Radiology, 94:361,1970. 26. Hirata, T., Wolfe, C. B., Popp, R. L., Helman, C. H., and Feigenbaum, H.: Estimation of left atrial size using ultrasound. Amer. Heart J., 78 :43, 1969. 27. Joyner, C. R., Hey, B., Johnson, J., and Reid, J. M.: Reflected ultrasound in the diagnosis oftricuspid stenosis. Amer. J. Cardio!., 19:66,1967. 28. Kaplan, S.: Congenital mitral stenosis. In Watson, H., ed.: Paediatric Cardiology. London, Lloyd-Luke Ltd., 1968. 29. Kirklin, J. M.: Cited by Van Praahg, R. (Personal communication). Circulation, 38:445, 1968. 30. Levin, S. E., and Barlow, J. B.: Hypoplastic left heart syndrome with clinical features of "reversed coarctation". South Afr. Med. J.,44:320, 1971. 31. Lucas R. V., Anderson, R. C., Amplatz, K., and Adams, P. Jr.: Congenital causes of pulmonary venous obstruction. PEDIAT. CLIN. N. AMER., 10:781, 1963. 31a. Lundstrom, N. R.. and Edler, I.: Acta Paediat. Scandinav., 60:117,1971. 32. Medd, W. E., Neufeld, H. N., Weidman, W. H., and Edwards, J. E.: Isolated hypoplasia of the right ventricle and tricuspid valve in siblings. Brit. Heart J., 23 :25, 1961. 33. Neill, C. A., and Tuerk, J.: Aortic atresia, hypoplasia of the ascending aorta and underdevelopment of the left ventricle. In Watson, H., ed.: Pediatric Cardiology. London, Lloyd-Luke, Ltd., 1968. 34. Neufeld, H. N., Lucas, V. R., Lester, R. G., Adams, P. Jr., Anderson, R. C., and Edwards, J. E.: Origin of both great vessels from the right ventricle without pulmonary stenosis. Brit. Heart J.,24:393, 1962. 35. Popp, R. L., and Harrison, D. C.: Ultrasonic cardiac echography for determining stroke volume and regurgitation. Circulation, 10:493, 1961. 36. Popp, R. L., Wolfe, S. B., Hirata, T., and Feigenbaum, H.: Estimation of right and left ventricular size by ultrasound. A study of echoes from the interventricular septum. Amer. J. Cardiol., 24:523,1969. 37. Ruttenberg, H. D., Neufeld, H. N., Lucas, R. V., Carey, L. S., Adams, P. Jr., Anderson, R. C., and Edwards, J. E.: Syndrome of congenital cardiac disease with asplenia. Amer. J. Cardio!.,13:387,1964. 38. Shone, J. D., Sellers, R. D., Anderson, R. C., Adams, P., Jr., Lillehei, C. W., and Edwards, J. E.: The developmental complex "parachute mitral valve", supravalvular ring of the left atrium, subaortic stenosis and coarctation of the aorta. Amer. J. Cardio!., 11 :714, 1963. 39. Segal, B. L., Likoff, W., and Kingsley, B.: Echocardiography: Clinical application in mitral stenosis. J.A.M.A., 195:161,1966. 40. Segal, B. L., Ukoff, W., and Kingsley, B.: Echocardiography: Clinical application in combined mitral stenosis and mitral regurgitation. Amer. J. Cardiol., 19 :42, 1967. 41. Shah, P. M., Gramiak, R., and Kramer, D. H.: Ultrasound localisation of left ventricular outflow obstruction in hypertrophic obstructive cardiomyopathy. Circulation, 11 :3, 1969. 42. Utian, L. B., Segal, B. L., and Ukoff, W.: Echocardiography in congenital heart disease: Preliminary observations, Amer. J. Cardiol., 19: 74, 1967. 43. Van Praagh, R., Van Praagh, S., Vlad, P., and Keith, J. D.: Diagnosis of the anatomic types of single or common ventricle. Amer. J. Cardio!., 15:345,1965. 44. Van Praagh, R.: What is the Taussig-Bing malformation? Circulation, 38:445,1968. 45. Witham, A. C.: Double outlet right ventricle. A partial transposition complex. Amer. Heart J., 53:928,1959. 46. Zaky, A., Grabhorn, L., and Feigenbaum, H.: Movement of the mitral ring: A study in ultrasound cardiography. Cardiovasc. Res., 1 :121,1967. 47. Zaky, A., Nasser, W. K., and Feigenbaum, H.: A study of mitral valve action recorded by reflected ultrasound and its application in the diagnosis of mitral stenosis. Circulation, 38:789,1968. Cardiac Clinic Groote Schuur Hospital Cape Town, South Africa