echocardiographic identification of the mitral valve prolapse syndrome

Echocardiographic Identification of the Mitral Valve

Prolapse Syndrome

ANTHONY N. DeMARIA, M.D.

ALEXANDER NEUMANN, B.S.

GARRETT LEE, M.D.

DEAN T. MASON, M.D.

Davis. California

From the Section of Cardiovascular Medicine, University of California School of Medicine, Davis, California. This study was supported in part by Research Program Project Grant HL 14780 from the National Heart and Lung Institute. NIH. Be- thesda, Maryland, and grants from California chapters of the American Heart Association, Dallas, Texas. Requests for reprints should be addressed to Dr. Anthony N. DeMaria, Section of Cardiology TE172. School of Medicine, University of California, Davis, California 95616.

The data presented herein would indicate that mitral valve prolapse may be represented by a variable spectrum of abnormalities on the echocardiogram. Utilizing all the abnormalities described, echographic evidence of mitral valve prolapse may be detected in most patients with this disorder. However, evidence of mitral valve prolapse may also be observed in a large contingent of asymptomatic patients without other clinical manifestations of cardiac disease. The biologic significance of these echographic abnormalities remains uncertain and constitutes an important area for future investigation.

Although the mitral valve prolapse syndrome has been one of the major subjects of interest and investigation among cardiologists in recent years, uncertainty persists regarding many clinical aspects of this cardiac disorder. Thus, considerable controversy continues regarding the exact prevalence, clinical significance and prognosis of the mitral prolapse syndrome [l-lo]. In a similar fashion, the ultrasound diagnosis of the mitral valve prolapse syndrome continues to be one of the principal unresolved areas in echocardiography today [4,11 ,121. In this presentation we will critically consider the available data regarding the echographic identification of mitral valve prolapse and indicate the aspects in which our understanding is still incomplete.

Appreciation of the variable spectrum of echocardiographic manifestations of mitral valve prolapse is facilitated by a clear understanding of the echo pattern observed in normal people. Figure 1 illustrates a representative mitral valve echogram obtained from a normal subject in our laboratory. Both anterior and posterior mitral leaflets are visualized in the area of the atrioventricular groove seen to the left of the echogram, whereas only the anterior leaflet is recorded as the ultrasound beam was arced superiorly as shown to the right of the tracing. With the onset of ventricular systole, the anterior and posterior leaflets come into apposition to yield a single echo which exhibits a gradual anterior motion during systole attributed to forward motion of the mitral valve annulus as the left ventricle empties and the left atrium fills. Although multiple mitral echoes are not infrequently obtained during systole, they rarely number more than three and characteristically manifest parallel motion. Thus, normal mitral valve motion on an echogram during systole consists of a gradual anterior movement of both leaflets throughout this phase of the cardiac cycle.

It was not long after the recognition that the auscultatory findings of a midsystolic click and/or late systolic murmur actually represented

June 1977 The American Journal of Medicine Volume 62 619

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Figure 1. An echocardiogram of the mitral valve obtained in a normal subject.

prolapse or posterior displacement of the mitral leaflets into the left atrium during systole, that Dillon and associates [ 131, and Kerber and colleagues [ 141 inde- pendently described a characteristic echocardiographic abnormality manifested by patients with this disorder. Figure 2 demonstrates the finding these investigators described and illustrates posterior buckling of the mitral leaflets in midsystole. Thus, in this echogram obtained

Figure 2. Mitral valve echogram obtained in a patient with the mitral valve prolapse syndrome illustrating an abrupt posterior movement of the mitral valve leaflets into the left atrium in midsystole (arrow) .

ECHOCARDIOGRAPHIC IDENTIFICATION OF MITRAL VALVE PROLAPSE SYNDROME-DeMARIA ET AL.

from a patient with mitral valve prolapse, the mitral leaflets come together at the onset of systole and pur- sue a slightly anterior course until midsystole when, coincident with the occurrence of a prominent nonejection click, the leaflets manifest an abrupt posterior motion into the left atrium. This pattern was not observed in any condition other than mitral valve prolapse, was able to be recorded in the majority of patients with prolapse and became recognized as the echocardiographic hallmark of the mitral valve-prolapse syndrome.

It was in this setting that, in a one week period of time, two patients were seen at the University of Cali- fornia, Davis-Sacramento Medical Center with the auscultatory findings of a midsystolic click and late systolic murmur, and unequivocal evidence of mitral valve prolapse upon cineangiogram in whom midsystolic buckling could not be demonstrated on echogram [ 1 I]. Figure 3 illustrates an end-systolic frame of the right anterior oblique cineangiogram in one of these patients and incontravertibly demonstrates prolapse with scalloped protrusion of the mitral valve posterior to the mitral annulus. The echocardiogram obtained in this patient is exhibited in Figure 4 and reveals a pattern of continuous pansystolic bowing or hammocking of the mitral leaflets throughout systole rather than abrupt midsystolic buckling. Stimulated by this experience, we then conducted a retrospective study of the echocardiographic findings in patients in whom mitral valve prolapse was documented by biplane cineangiography. Currently our patients number 5 1, and we will include data obtained in all of them in this presentation.

Echograms in 26 of the 51 patients with prolapse

Figure 3. An endsystolic frame of the right anterior oblique left ventricular cineangiogram in a patient with the mitral valve prolapse syndrome.

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ECHOCARDIOGRAPHIC IDENTIFICATION OF MITRAL VALVE PROLAPSE SYNDROME-DeMARIA ET AL

Figure 4. The echocardiogram of the mitral valve obtained in the same patient illustrated in Figure 3 demonstrating continuous pansystolic bowing of the mitral leaflets throughout sys- to/e.

evaluated in this study revealed the originally described midsystolic posterior motion of the mitral valve as illustrated in Figure 2. In addition to this abnormal mitral movement during systole, nearly all patients were found to manifest a wide excursion of the anterior leaflet in diastole consisting of an amplitude of 25 mm or greater, usually resulting in an abutting of the anterior leaflet upon the interventricular septum in early diastole. Further, echograms in patients with mitral valve prolapse have been characterized by multiple (usually greater than three) systolic echoes. Thirteen of the patients with mitral valve prolapse who manifested midsystolic buckling on the echogram exhibited a straight or anterior motion in early systole prior to the

prolapse as is demonstrated in Figure 2. However, an equal number of patients manifested posterior movement of the mitral leaflets from the onset of systole with a superimposed backward buckling in midsystole, as can be seen in Figure 5. In this patient, the mitral leaflets course posteriorly from the onset of systole with an accentuated brisk posterior motion superimposed in midsystole. Such an echogram may well represent an intermediate form between the classic midsystolic buckling and pansystolic bowing.

Seven patients in our study manifested the classic clinical and catheterization features of torn mitral chordae tendineae. All of these patients were found to have both pansystolic bowing and flail diastolic motion

lcm

Figure 5. An echocardiogram of the mitral valve in a patient with the mitral prolapse syndrome illustrating posterior movement of the mitral leaflets from the onset of systole with a superimposed backward buckling in midsystole.


ECHOCARDIOGAAPHIC IDENTIFICATION OF MITRAL VALVE PROLAPSE SYNDROME-DeMARIA ET AL

Figure 6. An echocardiogram obtained in a patient with torn chordae tendineae illustrating a flail portion of the posterior mitral leaflet (arrow).

Figure 7. Mitral valve echogram obtained in a patient in whom myxomatous degeneration of the mitral leaflets was documented at surgery. Note that the pansystolic motion of the mitral valve leaflets reaches its nadir in midsystole.

of either the anterior or posterior leaflet on echogram. Figure 6 represents the echogram of one patient with a torn chordae tendineae and demonstrates multiple mitral echoes, all of which are recorded throughout systole and exhibit posterior hammock-like contour with an anterior concavity. In addition, the completely flailed aspect of a portion of the posterior leaflet is evident in diastole as it moves forward from its posterior position in the left atrium in systole. Midsystolic buckling was not

seen during ultrasound examination in any patient with torn chordae tendineae.

Pansystolic motion of the mitral leaflets was manifested on the echogram of 16 patients in this group with mitral valve prolapse on cineangiogram. Figure 7 illustrates the ultrasound findings in a patient in whom myxomatous degeneration of the mitral leaflets was documented at surgery and manifests multiple systolic mitral echoes, all of which show a bowing motion

Figure 6. A mitral valve echogram obtained in a patient with mitral valve prolapse. The left panel illustrates hammock-like movement of the mitral valve throughout systole. The right panel demonstrates collapse of the mitral valve leaflets into the left atrium during systole.



----. _ _ ..- ..“_.. ..^ .---_” --“,---_.--., __,. _ _ .”

Figure 9. Echocardiogram through the sector of the aorta, aortic valve leaflets and left atrium obtained in a patient with the mitral valve prolapse syndrome. Note the signals obtained in the mid-left atrium (arrows) probably emanating from the mitral valve leaflets.

throughout systole. Importantly, the pansystolic motion

reaches its nadir in the middle of this portion of the

cardiac cycle. Of note, although the mitral leaflets

prolapsed throughout systole, mitral regurgitation and

its resultant murmur were limited to end-systole in this

patient.

Figure 8 represents the echogram obtained in an-

other patient who manifested pansystolic bowing of the

mitral leaflets during systole. The left panel illustrates

hammock-like movement of the mitral valve which is

pursued through systole and which reaches its nadir at

midsystole. The right panel was obtained from the same

patient and demonstrates the echogram of the anterior

mitral. leaflet observed when the ultrasound transducer

was angled more superiorly through the plane of the left

atrium. The anterior mitral leaflet in this tracing appears

to collapse with the onset of systole and billow poste-

riorly into the left atrium. Mitral valve collapse of this

nature was also observed on the echogram in con-

junction with midsystolic buckling of the leaflets and

was a common finding in patients with mitral valve

prolapse in our study.

Figure 9 illustrates the echogram of the anterior

mitral leaflet obtained during scanning of the sector of

the left atrium in another patient with the mitral valve

prolapse syndrome. Severe prolapse of the mitral valve during systole resulted in the ability to obtain echo

signals from the mitral leaflets in the left atrium even

through the sector of the aortic leaflets as seen in this

echogram. Thus, the ability to record echoes from the

mitral leaflets in the sector of the aortic leaflets rep-

resents another abnormality which may be observed

on the echogram in patients with the mitral valve pro-

lapse syndrome.

Several additional interesting observations regarding

the echogram in the mitral valve prolapse syndrome

were made during the course of the study. Thus, it was

recognized that occasionally a disparity existed be-

tween the temporal relation of the auscultatory phe-

nomenon produced by mitral valve prolapse and the

actual posterior motion on the echogram. Figure 10 il-

lustrates this disparity in one patient and demonstrates

the occurrence of an early nonejection click prior to the

onset of prolapse of the mitral leaflets on echogram

which occurs in midsystole. In our study we also ob-

served patients who manifested midsystolic clicks on

the phonocardiogram and pansystolic prolapse on the

echogram. As regards the frequency with which each

mitral leaflet is involved in mitral prolapse, it was ob-

served that in the majority of patients all echoes ob-

tained from the mitral leaflets during systole exhibited

abnormal posterior motion. The echogram depicted in

Figure 10 again illustrates this feature and, although one

cannot ascertain which of the multiple systolic echoes

arise from the anterior or posterior mitral leaflets, all

echoes recorded manifest midsystolic buckling. In view

of these echographic findings it would appear that, from a functional standpoint, both mitral leaflets participate

in the posterior prolapse in nearly all cases.

The occurrence of pansystolic posterior motion of

the mitral valve on the echogram in patients with pro-

lapse has also been recognized by Shah and associates



Figure 70. Simultaneous echo- and phonocardiograms obtained in a patient with the mitral valve prolapse syndrome illustrating the appearance of a click early in systole preceding the appearance of prolapse on the mitral valve echogram.

[ 151 and Popp and co-workers [ 161 in similar investi- gations. However, the high prevalence of this echographic manifestation in our patients was somewhat surprising. We, therefore, considered the possibility that the midsystolic buckling occurred only in a highly lo- calized area of the echogram and that pansystolic bowing or no abnormality at all was recorded when this area was not examined. Figure 11 demonstrates an echographic scan from apex to base in a patient with mitral prolapse and exhibits midsystolic buckling only in a specific echographic plane which may be completely undetected in other sectors. Thus, it is important to be aware that in certain patients with prolapse the mitral echogram may appear normal with one transducer angulation and reveal abnormalities only when the ultrasound beam traverses a specific portion of the mitral leaflets. Similarly, we have examined patients in whom pansystolic prolapse was recorded with one transducer position and midsystolic buckling with another. However, diligent echographic scanning from multiple transducer positions has revealed that pansystolic bowing continues to be the solitary ultrasound manifestation of mitral valve prolapse in a definite proportion of patients with this disorder.

That pansystolic posterior bowing of the mitral leaflets should be the only abnormality recordable on the echogram in a given patient with prolapse is readily understandable from physiologic as well as technical

considerations. As regards the pathophysiology of this cardiac disorder, previous studies have demonstrated that the onset of prolapse of the mitral leaflets during systole is determined by the relationship between left ventricular volume and the length of the mitral leaflets and chordae tendineae [ 17-191. Thus, the initiation of a midsystolic click on the phonocardiogram [ 13,17,19,20] and prolapse of the mitral leaflets on both the echogram [ 13,201 and cineangiogram [ 181 have been shown to occur earlier in systole in response to maneuvers which reduce ventricular volume, such as head-up tilting and amyl nitrite inhalation; indeed, late- systolic buckling.on the echogram has been converted to pansystolic bowing by such interventions [20]. However, both the auscultatory and ultrasound manifestations of prolapse have been shown to originate at a relatively constant left ventricular dimension of the echogram during these maneuvers [ 19,201. Thereby, it is apparent that the relationship between left ventricular volume and leaflet-chordal length will be such as to result in pansystolic prolapse either continuously or intermittently in some patients and that a bowing posterior motion throughout systole will be recorded on the echogram in this setting. Additionally, studies by Sahn and associates [21] employing cross-sectional echocardiography in children have revealed that mitral valve prolapse is a composite of superior and posterior motion, and that the pattern of leaflet movement in-

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ECHOCARDIOGRAPHIC IDENTIFICATION OF MITRAL VALVE PROLAPSF SYNDROME-DeMARIA ET AL

Figure 11. An echocardiographic scan from apex to base in a patient with the mitral valve prolapse syndrome. Note that midsystolic buckling may be observed only in a specific echographic plane (arrow) and that it may be completely undetected in other sectors.

scribed on the echogram will be related to transducer angulation. These investigators reported the frequent occurrence of midsystolic buckling as well as pansystolic bowing in the same patient. Thus, from both physiologic and technical standpoints, it is easy to un- derstand how pansystolic hammocking may be the only abnormality recorded during an M-mode ultrasound examination of a patient with mitral prolapse.

Utilizing these various aforementioned echographic patterns, echocardiography has proved to be a most efficacious method for the diagnosis of the mitral valve prolapse syndrome in our hands. Thus, all but two patients determined to have prolapse by cineangiography were found to have one of the previously described abnormalities on echocardiogram. Moreover, we have been able to record an echocardiographic abnormality in 90 per cent of the patients with the auscultatory findings of a midsystolic click and/or a late systolic murmur. Experience in our laboratory has revealed that 66 per cent of the patients manifested midsystolic buckling, whereas 34 per cent exhibited pansystolic bowing. It therefore appears firmly established that echocardiography detects mitral valve prolapse with a high degree of sensitivity. However, a review of rou- tine echoes obtained in our laboratories revealed that some evidence of mitral valve prolapse could be recorded in approximately 6 per cent of all patients re- ferred for ultrasound examination. Further, we and others have noted the appearance of echocardiographic patterns consistent with the presence of mitral valve prolapse in asymptomatic persons without other evidence of this disorder [4,11,22,23]. Therefore, it is clear that more data are needed to establish the specificity and significance of the echocardiographic patterns just described in regard to the presence of the mitral valve prolapse syndrome.

A major portion of the confusion regarding the sen-

sitivity and specificity of echographic abnormalities in the detection of the mitral valve prolapse syndrome appears to be related to technical factors involved in the performance and interpretation of the ultrasound examination. Thus, a number of studies have documented the dependence of the pattern of systolic mitral valve movement on the echocardiogram upon the position of the ultrasound transducer on the chest wall [4,21,24,25]. It is now recognized that the motion of the mitral valve leaflets is influenced by movement of the entire heart, the mitral valve annulus and, indeed, that it may vary along the extent of the mitral valve leaflet itself. The net result of this variable mitral leaflet motion may be to give the appearance of posterior displacement into the left atrium during systole which is referable only to movement of the valve away from the transducer as the left ventricle empties and the left atrium fills during this portion of the cardiac cycle. The ability to record such a pseudodiagnostic pattern of mitral valve prolapse on the echogram is especially prevalent when the transducer is positioned high in the second or third intercostal space and angled markedly inferiorly. Therefore, the most accurate technic for the echocardiographic detection of mitral valve prolapse requires that the ultrasound transducer be positioned in the intercostal space which allows the simultaneous recording of the mitral valve leaflets in front of the left atrium with the transducer most perpendicular to the chest wall.

Additional factors of importance in the recognition of true mitral valve prolapse relating to the interpretation of echocardiograms have also been emphasized [4,12,16]. Thus, pansystolic bowing on the echocardiogram has been found to correlate best with other evidence of mitral valve prolapse when the hammocking motion of the mitral leaflet is a continuous smooth movement which begins at the onset of systole


Figure 12. Echocardiogram obtained in a normal subject without auscultatory or cineangiographic evidence of the mitral valve prolapse syndrome. Although the mitral valve leaflets continue to move posteriorly in ear/y systole, a gradual normal anterior movement of the mitral valve leaflets is observed thereafter.

and reaches its nadir at midsystole. Figure 12 represents an echocardiogram which was recorded in a patient without any auscultatory or cineangiographic evidence of mitral valve prolapse syndrome. Note that although the mitral leaflets move slightly posteriorly just following the C point at the onset of systole, there is a subsequent straight gradual anterior movement of the mitral valve leaflets in the normal fashion until the onset of diastole. Such posterior movement which reaches its nadir at early systole has not been found to correlate with other evidence of the presence of mitral valve prolapse in our experience. Finally, it has been observed that the mitral valve echogram in patients with the mitral valve prolapse syndrome frequently manifests ancillary abnormalities, including an increased amplitude of excursion in diastole as well as multiple ethos during systole. On occasion, the mitral valve leaflets may also appear to be thickened on the echocardiogram in patients with the mitral valve prolapse syndrome.

ECH~CAI~D~~~~APH~C IDENTIFICATION OF MITRAL VALVE PROLAPSE SYNDROME-DeMARlA ET AL

Although such abnormalities as increased diastolic amplitude and multiple echoes of the mitral valve are nonspecific, and indeed may also be observed in normal subjects, such irregularities appear to be encountered with increased frequency in patients with the mitral valve prolapse syndrome. Therefore, one should be cautious of making the diagnosis of this disorder based upon the presence of only pansystolic bowing of the mitral leaflets during systole in the absence of these ancillary findings.

A major problem in establishing the true sensitivity and specificity of the echocardiogram in the recognition of patients with mitral valve prolapse syndrome consists of the lack of an adequate “gold standard” by which to unequivocally establish the existence of this disorder. Accordingly, although some workers have questioned whether echocardiography results in a major degree of overdiagnosis of the mitral valve prolapse syndrome, several recent studies have detected auscultatory abnormalities characteristic of this disorder in from 6 to 17 per cent of otherwise healthy women ,[4,5,22]. Therefore, it would be anticipated that cardiac ultrasound would reveal abnormalities in approximately an equivalent percentage of cases. In this regard, a recent study by Markiewicz and associates [4] attempted to relate the presence of abnormalities indicative of mitral valve prolapse on physical examination to those obtained by echocardiography in a group of 100 presumably healthy young women. These investigators were able to establish a uorrelation between certain echocardiographic patterns of mitral valve motion during systole and the findings on physical examination of nonejection clicks, late systolic murmurs and pansystolic murmurs. Specifically, this ultrasound abnormality consisted of either late systolic posterior buckling of the mitral valve leaflets or a smooth pansystolic an- teriorly concaved hammock-shaped movement of the mitral leaflets which deviated more than 2 mm from a line connecting the C and D points of the mitral valve echogram. However, it was observed in this study that these echo patterns were absent in 41 per cent of the patients with auscultatory evidence of mitral valve prolapse; conversely, auscultatory abnormalities characteristic of mitral valve prolapse were not observed in 33 per cent of the subjects who manifested these correlative echocardiographic abnormalities. Thus, it is obvious that the determination of the echocardiographic sensitivity and specificity in the recognition of the mitral valve prolapse syndrome is depen- dent upon the criteria for diagnosis of this disorder.

Stimulated by the apparent frequent occurrence of a disparity between the ultrasound and auscultatory findings of the mitral valve prolapse syndrome, we turned to the cineangiogram as the method of establishing the presence or absence of the mitral valve


ECHOCARDIOGRAPHIC IDENTIFICATION OF MITRAL VALVE PROLAPSE SYNDROME-DeMARIA ET AL.

. . Figure 13. Echocardiogram of the mitral valve leaflets obtained in the patient without evidence of mitral valve prolapse on clinical examination but with frequent premature ventricular contractions. Note that the premature ventricular contractions frequently result in a late systolic posterior buckling movement of the mitral valve leaflets into the left atrium.

prolapse syndrome with certainty. However, the cineangiographic criteria of mitral prolapse appeared somewhat imprecise. Therefore, we conducted a study to assess the reliability of the left ventricular cineangiogram in the diagnosis of mitral valve prolapse. The biplane left ventricular cineangiograms of 13 patients were selected from our files at the University of Cali- fornia at Davis-Sacramento Medical Center. Three of these patients had clinical and echocardiographic evidence of the mitral valve prolapse syndrome, two patients were totally devoid of evidence of the mitral valve prolapse syndrome, and eight subjects were considered to have equivocal clinical findings for the presence of this disorder. The ventriculograms were then examined by 20 observers consisting of cardiologists and cardiovascular radiologists from several medical centers. The results revealed that the cineangiogram was be- lieved to be equivocal by 20 per cent or more of the examiners in 10 of the 13 patients. Strikingly, despite the fact that several patients were selected either for their obviously normal findings or blatant manifestations of mitral valve prolapse, there was not 100 per cent agreement in a single case. Further, when the observers were required to indicate whether they would regard patients in the equivocal category as being normal or having mitral valve prolapse, there continued to be a major disagreement in seven of the 13 patients. Thus, although these patients were selected in large measure

because of equivocal findings on physical examination and echocardiograms, it would nevertheless appear that the cineangiogram does not provide an appropriate method for the precise detection of mitral valve prolapse.

Therefore, due to the lack of an adequate “gold standard,” at the present time it is uncertain whether the mitral valve prolapse syndrome is a common disorder, the prevalence of which has been recognized only by the advent of echocardiography, or if the echocardiographic abnormalities observed represent a variant of normal mitral valve motion. The central question remaining unanswered is whether the echographic abnormalities described are associated with the known complications of mitral valve prolapse, such as sudden death, bacterial endocarditis and hemody- namically significant mitral regurgitation; this remains an important area for future investigation.

Before concluding there are several additional points we would like to touch upon. Mitral valve prolapse syndrome has been found to be present in a substantial number of patients with atrial septal defects [26-281. Even with signs of major prolapse on the cineangiogram, however, we have found it difficult to record mitral valve prolapse on the echogram in these patients due to drop out of the mitral valve in systole, perhaps sec- ondary to alterations in left ventricular size and location within the thorax. In addition, a recent report has indi-



cated that premature ventricular contractions may in- duce prolapse of the mitral leaflets on the echogram in a significant percentage of patients [29]. Figure 13 represents the echogram of one such patient obtained in our laboratory. Note that the occurrence of premature ventricular contractions produces a midsystolic posterior motion of the mitral echogram. In our experience, prolapse is induced by premature ventricular contractions in only a small percentage of patients and characteristically consists of a posterior motion of minor amplitude, rather than major protrusion of the mitral leaflets into the left atrium. Finally, false-positive patterns of mitral valve prolapse on the echogram, including midsystolic buckling of the mitral leaflets, have been observed in the presence of pericardial effusion [30]. These ultrasound abnormalities resolve with elimination of the pericardial fluid and presumably are related to the influence of an exaggerated motion of the entire heart during the cardiac cycle due to the loss of the restraining forces of the adjacent structures in the mediastinum. Alternately, mitral valve prolapse oc- curring in the setting of pericardial effusion may be explained by an alteration in the relationship between left ventricular size and leaflet-chordal length due to a decrease in ventricular volume.

Tricuspid valve prolapse has been described as ac-

companying mitral valve prolapse in some patients [31]. Moreover, it has been proposed that midsystolic clicks may be referable to the tricuspid valve in the absence of mitral valve prolapse. In our experience, tricuspid valve prolapse has been recorded with diffi- culty, and echographic patterns consistent with the presence of this disorder have been observed in only a small number of patients.

Previous studies have documented the familial incidence of the characteristic auscultatory abnormalities associated with the mitral valve prolapse syndrome [ 321. Recently, Weiss and co-workers [ 241 evaluated the familial prevalence of this disorder and observed echographic evidence of mitral valve prolapse in 47 per cent of first-degree relatives (parents, siblings, children) of patients with mitral valve prolapse. The results of the study by these investigators indicated that mitral valve prolapse is transmitted in an autosomal dominant mode with reduced expressivity in males. However, similar studies in our laboratory as well as by other investigators [33] have not revealed a similar frequency of ultrasound abnormalities in relatives of patients with mitral valve prolapse. It would appear that more data will be required before the issue of the precise familial prevalence of mitral valve prolapse syndrome is determined.

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ECHOCARDlOGRAPHlC IDENTIFICATION OF MITRAL VALVE PROLAPSE SYNDROME- DeMARlA ET AL

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echocardiographic identification of the mitral valve prolapse syndrome

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