Echocardiography in Valvular Heart Disease Louis Evan Teichholz

CHOCARDIOGRAPHY is an important noninvasive technique that allows the study of the dimensions and movements of various cardiac structures, including the valves and chambers. The technical aspects and physical principles as well as the clinical usefulness in various disease settings have been previously reviewed. ~-6 The purpose of this review is to discuss this technique in relation to valvular heart disease.

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MITRAL VALVE Normal Mitral Valve

In order to fully understand the changes in the mitral valve echocardiogram in patients with valvular heart disease, a brief review of the normal motion pattern of the mitral valve is in order. The mitral valve has two leaflets, a larger anterior leaflet that is easily visualized by echocardiography and a smaller posterior leaflet that is much more difficult to visualize. The normal posterior leaflet shows mirror-image motion as compared to the anterior leaflet. The details of the motion of the mitral valve were originally described by Edler 7,a and further characterized by others. 9-~3 Figure 1 shows the normal pattern of motion of the anterior leaflet of the mitral valve. During systole (C-D), there is smooth anterior motion of both the anterior and posterior leaflets of the valve as the heart and mitral annulus rock anteriorly. In early diastole, the mitral valve opens rapidly (D-E), and then during and after rapid filling the mitral valve floats to midposition (E-F). With long cycle lengths, there may be some low-amplitude oscillatory motion during mid-diastole. With atrial systole, the valve reopens (A) and then closes during the onset of ventricular systole (A-C). The normal amplitude is 20-35 mm/sec, and the normal E-F slope, i.e., diastolic velocity, is 80-150 mm/sec. ~4 From the Cardiovascular Division, Department of Medicine, Peter Bent Brigham Hospital, and the Department of Medicine, Harvard Medical School, Boston, Mass. Supported by USPHS Grant 5 P01 HL 11306 and the Women's A id for Heart Research. Reprint requests should be addressed to Louis Evan Teichholz, M.D., Mt. Sinai Hospital, Fifth Avenue and lOOth Street, New York, N. Y. 10029. 9 1975 by Grune & Stratton, Inc.

Figure 2 shows an echocardiogram of a normal mitral valve. Mitral Stenosis

The study of the mitral valve in mitral stenosis was one of the earliest uses of diagnostic ultrasound, 7'15'16 since it afforded easy visualization of the anterior leaflet of the mitral valve and the many striking findings present in rheumatic heart disease. The pathophysiologic processes involved in rheumatic mitral stenosis include fusion of the commissures of the anterior and posterior leaflets of the mitral valve, fusion of the Chordae tendineae, leaflet thickening and deposition of calcium, left atrial dilatation, and decreased contractile function of the left atrium. An important finding in mitral stenosis is the decrease in the E-F slope as a manifestation of decreased left ventricular filling in early diastole 9'12'1s-21 (Fig. 3). This finding has its counterpart in the decreased rapid filling wave noted on the apexcardiogram. In the presence of a mobile valve, the E-F slope has been shown to be related to the severity of the mitral s t e n o s i s . 9'15'16'22-24 Severe mitral stenosis with a valve area of 2.2 cm/sq m). Calcification shows up as thick multiple echoes within the root s3,s4,58 (Fig. 12). In a heavily calcified valve, it may be impossible to obtain a

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Fig. 12. Calcification in aortic valve and root. Echo shows multiple echoes within the root that persist on the echoes are progressively attenuated. The normal aortic cusp motion is not seen.

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Fig. 13. Mild aortic stenosis. The aortic valve cusps are visualized and show decreased excursion. (From Teichholz LE: Echocardiography slide set, Tampa Tracings; by permission.)

good picture of the valve leaflets, and the normal boxlike motion may be obscured. If two fine, mobile cusps are visualized in adults with acquired aortic stenosis, aortic stenosis with a significant gradient can be excluded. 3 The average separation o f the cusps during systole in normals was 1.9 cm with a range of 1.6-2.6 cm. Recently, it has been shown that if this orifice diameter is less than 0.6 cm, this would be associated with a gradient greater

Fig. 14. Aortic root and valve from a patient with bicuspid aortic valve. The upper and lower arrows point to the walls of the aortic root. The middle arrow points to the diastolic echo of the aortic valve, which is eccentrically placed.

than 55 mm Hg. If the measurement, however, were between 1.3 and 2.0 cm, this would be associated with a gradient less than 35 mm Hg. s9 Figure 13 shows a patient with mild aortic stenosis with decreased aortic valve excursion. However, it ,should b e noted that decreased excursion of the aortic valve may also be seen in conditions other than aortic stenosis, most notably those with low cardiac output states, s9 In congenital aortic ste-

ECHOCAR DIOG R APHY

nosis, there can be a significant gradient with (1) a lack of calcium in the aortic valve or root and (2) relatively normal aortic valve motion. Echocardiography, therefore, has not been found to be useful in this condition. However, bicuspid aortic valve has recently been diagnosed by the use of ultrasound using the criteria of a large asymmetrically placed cusp with marked eccentricity of the aortic valve cusp echoes in diastole with multilayered diastolic echoes 6~ (Fig. 14). Echocardiography has also been helpful in evaluating the effects of systolic overload on the left ventricle as related to the development of increased thickness of the walls of the left ventricle. The determination of left ventricular wall thickness is accurate and can be correlated with direct measurements of wall thickness of postmortem specimens. 61'6s

Aortic Insufficiency The diagnosis of aortic insufficiency rests not with the examination of the aortic valve but rather with examination of the mitral valve, since generally there are no characteristic findings of aortic valve motion that suggest a diagnosis of aortic insufficiency. The useful finding in aortic insufficiency is a rapid, high-frequency fluttering of the mitral valve 66-68 (Fig. 15). The mechanism for this fluttering is presumably the same as that offered to explain the Austin-Flint murmur in this condition. 69'7~ The leak through the aortic valve causes blood to strike the anterior leaflet of the mitral valve and set it in motion. In some cases, fluttering of the posterior leaflet of the mitral

Fig. 15. Mitra| valve echocardiogram from a patient with aortic insufficiency. There is marked high frequency "fluttering" of the anterior leaflet of the mitral valve during diastole.

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valve, in addition to the anterior leaflet, may be noted. This finding can occasionally be found in patients in whom the murmur of aortic insufficiency is not appreciated. If the mitral valve is thickened and not sufficiently pliable to vibrate, as in mitral stenosis, the finding may be absent; however, we have seen this fluttering pattern in patients with mild stenosis. This rapid fluttering should be distinguished from the slower frequency of fluttering in atrial fibrillation 71 (Fig. 16) and the chaotic fluttering of a flail anterior leaflet of the mitral valve. Fluttering similar to that seen in aortic insufficiency has been seen in patients with ventricular septal defects and right-to-left shunts. In some cases of aortic insufficiency, the E-F slope is decreased. The explanation for the decreased slope is probably related to a decrease in left ventricular compliance. In many patients, there is a question of combined valvular disease; i.e., aortic insufficiency in association with mitral stenosis. The murmur of aortic insufficiency may be heard, as well as a diastolic rumble that could represent mitral stenosis or the Austin-Flint murmur. The echocardiogram may be very helpful in the differentiation of these two conditions by the use of the following criteria: (1) In aortic insufficiency without mitral stenosis, the A wave of the anterior leaflet of the mitral valve tends to be preserved in contrast to the findings observed in mitral stenosis. (2) The mitral valve diastolic velocity (E-F slope) is usually greater than 50 mm/sec in aortic insufficiency, while in mitral slenosis values of less than 50 mm/sec, usually less than 35 mm/sec, are seen.

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Fig. 16. L o w frequency oscillation o f mitral valve secondary to fibrillatory waves from a patient with atrial fibrillation w i t h o u t intrinsic mitral valve disease. (From Teichholz LE: Echocardiography slide set, Tampa Tracings; by permission.)

If there is an increase in the left ventricular enddiastolic pressure, one may also see a notch on the A-C slope 72 (Fig. 17). This has been reported in various conditions, and we have frequently seen this finding in patients with aortic insufficiency. A helpful adjunct to the diagnosis of aortic insufficiency is the finding of a dilated hyperdynamic left ventricle secondary to the left ventricular volume overload. ~3 In acute, severe aortic insufficiency, occasionally there is premature closure of the mitral valve that can be detected on the echocardiogram. In this case, the mitral valve becomes fully closed before the onset of the QRS complex. 68

Fig. 17. Mitral valve echo from a patient with increased left ventricular end diastolic pressure. The "notch" on the A - C slope is indicated in the last complex by the' arrow 9 (From Teichholz LE: Echocardiography slide set, Tampa Tracings; by permission.)

TRICUSPID VALVE The normal tricuspid valve has a motion pattern similar to that of the mitral valve 29 (Fig. 18). The posterior septal cusp is difficult to visualize. It is very difficult to record the entire motion of the tricuspid valve in normal subjects, and if one easily records a tricuspid valve, this usually indicates right ventricular enlargement. Tricuspid stenosis can sometimes be diagnosed by the finding of a decrease in the E-F slope of the tricuspid valve. 9'29"74 However, just as in the case ofmitral valve disease, this is not specific for tricuspid stenosis and can also be seen in other processes that cause a decreased filling rate of the right yen-

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tricle) 4 Fluttering of the tricuspid valve has been reported in pulmonic insufficiency, 14'75 and rapid diastolic slopes have been recorded in tricuspid insufficiency. ~4 In addition, with right ventricular diastolic overload, one will see an increased right ventricular internal dimension measured from the anterior wall of the right ventricle to the right ventricular side of the interventricular septum and a paradoxical septal motion in which the septum during systole moves anteriorly toward the right ventricle rather than posteriorly towards the posterior wall of the left ventricle. This finding is seen in tricuspid ino sufficiency. ~6 In patients with valvular or other cardiac disease and an increased RVEDP, an echocardiogram showing a notch on the A-C slope of the tricuspid valve may be recorded. In addition, patterns with an A wave greater than the E point and with decreased C-D slope may be recorded in patients with an elevated initial diastolic pressure. No discussion of the tricuspid valve would be complete without some comments on Ebstein's anomaly] 7-8~ In the presence of Ebste~,n's anomaly, the tricuspid valve is usually found further to the left of the sternum, and the beam must, therefore, be oriented in that direction. Significant echocardiographic findings in Ebstein's anomaly of the tricuspid valve are: (I) large excursion of the tricuspid valve; (2) decreased E-F slope; (3) delayed closure of the tricuspid valve; and (4) abnormal paradoxical septal motion. It should be noted that the delayed closure of the tricuspid valve has been

seen in patients with Ebstein's anomaly with or without type B Wolff-Parkinson-White syndrome and thus appears to be associated with the delayed component of the first heart sound rather than the conduction abnormality. PULMONIC VALVE

Gramiak et al. 81 have discussed the normal anatomy and physiology of the pulmonic valve and the normal echocardiographic patterns. This valve is particularly difficult to study in adults. Although there have been some preliminary findings of valvular abnormalities in pulmonic stenosis and in pulmonary hypertension, 3 the number of instances in which this valve can be appreciated in adults is small enough to make it less useful diagnostically. PROSTHETIC VALVES

Characteristic echocardiographic patterns have been reported from various types of cardiac prostheses. 82-9s In general, parallel echoes from the cage and sewing ring are seen with superimposed motion of the poppet when the transducer is positioned along the axis of motion. When there is a silastic ball as the poppet, it may appear to be larger than the actual valve itself because the speed of sound is slower by a factor of 0.64 in silastic. 96 The prosthetic aortic valve has been found to be much more difficult to record than the prosthetic mitral valve, due in part to the orientation of the valve in the chest wall. Malfunction of prosthetic valves have been reported as characterized by a

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Fig. 19. Porcine (heterograft) valve prosthesis in the mitral position. The transducer was swept from the aortic root (on the left} to the prosthesis (on the right}. The motion of one of the valve cusps can be seen within the sewing ring of the prosthesis. (From Teichholz LE: Echocardiography slide set, Tampa Tracings; by permission.)

limitation of excursion, reduction in the velocity of the poppet motion, or inconsistent motion pattern of the poppet. 97'9a Fungal vegetations have been identified 99 as well as decreased motion secondary to clot a~176 and excessive rocking motion due to loss of support of the suture line. ~~ Recently, stented fascia lala grafts have been studied, x~ and we have looked at porcine mitral valves; the patterns seen in these patients represent a structure similar to a double aortic root and motion o f the porcine valve cusps can sometimes be visualized (Fig. 19). Of interest is the finding of abnormal septal motion in a large proportion of patients with either an aortic or a mitral valve prosthesis. ~~ The nature o f this abnormal motion is not clear at this time. This does not appear to be related to tricuspid insufficiency and may disappear with time after surgery. Combined use o f echocardiography and phonocardiography should allow one to follow serially individual patients with prosthetic valves and hopefully allow one to diagnose at an early stage manifestations of prosthetic valvular dysfunction. MISCELLANEOUS

CONDITIONS

Idiopathic Hypertrophic Subaortic Stenosis (IHSS} Echocardiography has proved to be a sensitive method for the diagnosis of idiopathic hypertrophic subaortic stenosis (IHSS). 1~176 The earliest description of the echocardiographic ab-

normalities in IHSS was that of abnormal motion of the anterior leaflet of the mitral valve (ALMV). l~176 The ALMV forms one side of the outflow tract of the left ventricle with the interventricular septum (IVS) forming the other boundary. In IHSS, there is a decrease in the outflow tract size, i.e., the distance between the ALMV and IVS. In addition, in IHSS with obstruction there is an abrupt systolic anterior motion of this leaflet (SAM) (Figs. 20A and B). The duration and extent of abnormality appears to be related to the severity of obstruction, m'112 This abnormality is lacking in patients without obstruction, but can be induced by maneuvers that increase the gradient such as the Valsalva maneuver, isoproterenol infusion, or inhalation of amyl nitrite.~~ ms,l~o The effect of propanolol therapy on SAM has been inconstantvarious groups reporting correction of this abnormality, 6'1~ while others have found no effect despite abolition or reduction of the gradient. ~~ Ventriculotomy has been shown to abolish both the gradient and the SAM in the majority of patients, mS'1~~ although this has not been seen by other observers. 112 Although the SAM is an important diagnostic finding in IHSS, care must be exercised to examine the tip of the ALMV because a form of systolic anterior movement can be seen in normals if one examines the ALMV in a position close to the mitral annulus. 6'11~ This is especially common in patients with hyperdynamic left ventricular motion with increased excursion of posterior wall and mitral annulus. This "systolic

ECHOCARDIOGRAPHY

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Fig. 20. Two examples of abnormal mitral valve motion in IHSS. Both show the systolic anterior motion (SAM) of the anterior leaflet of the mitral valve and decreased E-F slope. B also shows a notch on the A-C slope secondary to increased left ventricular enddiastolic pressure. (From Teichholz LE: Echocardiography slide set, Tampa Tracings; by permission.)

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hump" can be distinguished from the SAM of IHSS by taking care to examine the tip of the ALMV, which is usually at a position where the posterior leaflet is also visualized. Secondly, in IHSS there is abrupt posterior motion of the ALMV prior to diastole, while the annular motion blends into the diastolic opening motion of the ALMV. Other abnormalities of the mitral valve seen in IHSS are a decrease in the E-F slope secondary to decreased left ventricular compliance 1~176176 (Figs. 20A and B) and, occasionally, a notch on the A-C slope in the presence of an increased left ventricular end-diastolic pressure. In most cases,

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the ALMV appears to touch the IVS in early diastole, but this finding is not specific for IHSS and is seen in some patients with small or hyperdynamic left ventricles. Examination of the aortic root and valve cusps in patients with significant left ventricular outflow obstruction shows an abnormal pattern of motion of the aortic valve cusps, s'11~ There is normal initial opening followed by mid-systolic reopening. This finding has as its counterparts the mid-systolic dip in the carotid pulse tracing and the double apical systolic impulse. However, the echocardiographic finding that is

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Fig. 21. Asymmetric septal hypertrophy (ASH) in a patient with I HSS. The ratio of the thickness of the interventricular septum (IVS) to the posterior wall (PWLV) is approximately 13:1. (From Teichholz LE: Echocardiography slide set, Tampa Tracings; by permission.)

the most sensitive indicator of this disease is asymmetric septal hypertrophy 114-117 (Fig. 21), i.e., hypertrophy of the IVS so that the ratio of IVS thickness/posterior wall thickness is greater than 1.2/1. This finding may be found in patients without left ventricular outflow obstruction and in asymptomatic relatives of patients with IHSS] Is To avoid artifacts care must be taken to record and make measurements of the thickness of the IVS and posterior wall in the position just below the mitral valve. Recently, it has been suggested that ASH is not absolutely specific for IHSS but may be found in patients with right ventricular systolic overload as wellJ 19 The study of IHSS by echocardiography has not only been of aid in the diagnosis but has also aided in the study of the pathophysiology of this disorder. Recently, study of the IVS and ALMV in IHSS by B-scan ultrasonography lz~ has clearly demonstrated the displacement of the mitral valve anteriorly toward the IVS, probably as a result of abnormal orientation of the papillary muscles secondary to the left ventricular distortion caused by the marked septal hypertrophy. Subacute Bacterial Endocarditis

Echocardiography has recently been used to detect involvement of specific valves with vegetations secondary to subacute bacterial endocarditis.12~' 122

In these studies, vegetations were felt to be detected on valves if these vegetations were greater than 2 mm in diameter. Further work is necessary to confirm and extend these observations. A trial M y x o ma

Left atrial myxomas are usually pedunculated tumors arising from the interatrial septum, which may prolapse and obstruct the mitral valve orifice. Echocardiography has proved to be a very useful tool in the diagnosis of this disorderJ 23-~a7 Since each tumor is different in size, shape, location, and mobility, it is not surprising that the echocardiographic manifestations may be markedly varied. Usually, one sees multilayered, usually parallel echoes behind the mitral valve in diastole as the tumor prolapses into the mitral orifice. In some cases, the multiple echoes may also be seen in systole. Because of the obstruction to left atrial emptying and left ventricular filling caused by the tumor, there is also a decrease in the E-F slope. Although the use of echocardiography in the detection of left atrial myxoma has proved to be extremely useful, care must be taken to adjust the sensitivity or gain setting carefully in order to obtain adequate echocardiograms. The sensitivity should not be so high as to introduce artifacts. In addition to examining the echoes of the mitral valve, the left atrial cavity behind the aortic root

ECH OCAR DI OG RAPHY

299

should be examined carefully so as to visualize the echoes behind the mitral valve, and the absence of abnormal echoes in the left atrium behind the aortic root make the diagnosis of left atrial myxoma doubtful. Right atrial myxomas have also been studied using ultrasound. 138-14~ SUMMARY

Echocardiography is a useful new technique that allows for the diagnosis and assessment of the severity of various forms of valvular heart disease. It is a safe and noninvasive procedure that can

readily be used on the critically ill as well as the ambulatory patient. Since the examination can be easily repeated, echocardiography can be used to study a patient over an extended period of time to follow the severity of the disease. With proper care and experience in the performance and interpretation, the cardiologist can derive much useful information to aid in the initial evaluation and long-term follow-up of patients with various forms of valvular disease. With improvements in instrumentation and the use of newer techniques, the usefulness of ultrasound will be further enhanced.

REFERENCES

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ECHOCAR DIOGRAPHY

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TEICHHOLZ

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