Ultrasono-cardiographic Diagnosis of the Prolapsed Mitral Valve

Transcription

1 Ultrasono-cardiographic Diagnosis of the Prolapsed Mitral Valve Yoshio TERASAWA, M.D., Motonao TANAKA, M.D., Shigemi KOSAKA, M.D., Kiyoshi KONNO, M.D., Keiko NITTA, M.D.,* Makoto KASHIWAGI, M.D.,* Taiichiro MEGURO, M.D.,* Hisaharu HIKICHI, M.D., *Satoru WATANABE, M.D.,* Hisanao TAKEDA, M.D.,* Toshiaki EBINA, M.D.,* and Makoto TAKAMIYA, M.D.** SUMMARY The characteristic ultrasono-cardiographic (UCG) findings of prolapsed mitral valve were studied in 9 cases by means of ultrasonocardiotomography (UCT). The changes in degree and shape of the prolapsed valve were examined and the leaflet involved was identified. Of the 9 cases, 5 had prolapse of anterior, 3 had that of posterior leaflet and 1 had both. In all cases with midsystolic click and late systolic murmur or pansystolic murmur with late systolic accentuation, the prolapse of anterior leaflet was observed on UCT, and though UCG disclosed midsystolic buckling it was difficult to determine the exact timing of the prolapse by UCG alone. In the cases with rheumatic mitral regurgitation, the prolapse of posterior leaflet and the ballooning of anterior leaflet could easily be found on UCT, but the detection of the above-mentioned 2 findings was difficult by UCG alone. Three of the 9 cases were found to have prolapse of posterior leaflet by left ventriculography, whereas these 3 had prolapse of anterior leaflet on UCT. Hence, the diagnosis of prolapsed mitral valve based on the cineangiography may require re-evaluation. Additional Indexing Words: Prolapsed mitral valve Midsystolic click and late systolic murmur Ballooning the of the mitral valve Early SAM UBSEQUENT to the report of Barlow on the midsystolic click and late systolic murmur syndrome,1),2) lively interest has been directed toward the From the Department of Internal Medicine, Research Institute for Tuberculosis and Cancer, Tohoku University, Hirosemachi 4-12, Sendai 980, Japan. * Sendai Kosei Hospital, Hirosemachi, Sendai. ** Department of Radiology, Yamagata University, School of Medicine, Yamagata. A preliminary report of this work was reported at the 27th Scientific Meeting of the Japanese Ultrasonic Medical Society, Tokyo, March 30, Received for publication July 21,

2 176 TERASAWA, ET AL Ja p. Heart J. March, 1978 mechanism of these acoustical abnormalities.3)-35) Although the relationship between phonocardiogram and various types of prolapse has been discussed, no relationship has yet been established. In 1970, Shah and Gramiak reported the usefulness of UCG in the evaluation of the prolapsed mitral valve.17) Dillon reported the prolapse of posterior mitral leaflet in ) Since then numerous reports have appeared on the prolpase of either posterior or, in the rare occurrence, anterior leaflet. However, there has not been sufficient UCG evidence to distinguish the prolapse of posterior leaflet from that of anterior, and the echo source has never been identified.17)-26),32)-35) The only way to distinguish anterior from posterior leaflet has been the left ventriculography.10),18),19),21),23),25),26) This was possible in the present study by the application of UCT in combination with UCG. In addition, the characteristic UCG finding of prolapsed mitral leaflets were discussed. MATERIALS AND METHODS Nine cases were studied, 7 were male and 2 were female. Their ages ranged from 6 to 57 years with the mean of 25. Three cases had rheumatic mitral regurgitation (mean age, 30years), and 5 cases (mean age, 13 years) had no organic changes of the mitral valve. Two cases had midsystolic click and late systolic murmur. The remaining 3 cases had pansystolic murmur with late systolic accentuation without a click. The ninth case had papillary muscle dysfunction. This patient (57-year-old male) was admitted because of pulmonary tuberculosis, and later, lung cancer was detected at the site of tuberculosis, and several months thereafter the patient suffered from myocardial infarction. In this case the prolapse was observed on both mitral leaflets. Left ventriculography was carried out in 8 cases except the case of myocardial infarction, and the prolapse of posterior leaflet was detected in 3 cases by cineangiocardiography, but no prolapse of anterior leaflet was detected. The structure of the ultrasonic apparatus in the present study is described elsewhere.36)-49) A concave resonator of 2.25MHz made of barium titanate was used as an ultrasonic transducer. The radius of curvature was 100mm and the diameter was 30mm. The transducer for sector scanning was mechanically driven on a stereotaxic rack by a vinyl bag containing water on the chest wall. The transducer was set as close as possible to the chest wall (proximity immersed method), 37),3 along the left parasternal border in the 3rd, 4th or 5th intercostal spaces. First ultrasono-cardiotomograms (UCT) were taken along the longitudinal and then along different sections of the heart to record the mitral apparatus on different sectional planes. Thus the degree and position of prolapse of the mitral leaflet were confirmed and the leaflet which was involved in prolapse was identified on UCT. Then the ultrasono-cardiograms (UCG) were recorded. In every case, the data of UCT and UCG were gathered from 500 to 1,000 spots of 35mm films.

3 Vol.19 No.2 UCG OF PROLAPSED MITRAL VALVE 177 Hitherto the terms of prolapse,10),11),13) bulging, ballooning,12) and billowing35) have been used as synonyms to indicate protrusion of mitral leaflet toward left atrium. In this paper the following 2 words will be used to refer to the protrusion of the leaflet. Prolapse: Localized protrusion of mitral leaflet in which the angle formed by the prolapsing portion of the valve is acute. Bulging (ballooning or billowing): Protrusion of the entire leaflet to a minor extent with convexity toward left atrium. RESULTS I. Prolapse of anterior mitral leaflet A) Pansystolic prolapse The case in Fig.1 had pansystolic murmur and the intensity increased in late systole. There was no restriction in the movement of the mitral leaflet in which no organic lesion was found. The prolapse of anterior leaflet was observed clearly on UCT throughout the systole. The UCG findings which are considered to be characteristic of the anterior prolapse were examined in detail by UCT. 1) A small echo behind the anterior leaflet limited to early systole (Fig. 1-2) The ultrasonic beam hit the tip of prolapsing portion of the leaflet in early systole (Fig.1-A). During the course of systole it became impossible for the beam to hit against the prolapsing portion because there was a downward movement of mitral valve and because the degree of protrusion toward left atrium became much milder. 2) Three echoes in the latter half of systole (Fig.1-3) Three echoes were recorded in the latter half of systole, because the beam hit against the prolapsing anterior leaflet 3 times (Fig.1-C and 3). In the first half of systole the ultrasonic beam ran below the prolapsing portion. Therefore in this phase no echoes related to the prolapse could be observed on UCG along the direction of the beam shown in Fig ) Midsystolic notch and buckling (Fig.1-4) The ultrasonic beam ran below the prolapsing portion during the first half of systole (Fig.1-A and B). During the course of systole mitral valve moved downward and left atrium became dilated. As a result the prolapsing portion made a forward movement and thus a notch was formed (Fig.1-B, 4 and Fig.2-3). Then the degree of prolapse became more severe, because there was a change in shape and movement toward left atrium of the prolapsing portion and thus a midsystolic buckling was formed. In the section of the heart shown in Fig.2, the degree of prolapse of

4 178 TERASAWA, ET AL Jap. HeartJ. M arch, 1978 Fig.1. Holosystolic prolapse of anterior mitral leaflet. A 8-year-oldboy had holosystolic murmur with late increase. The prolapse was found in anterior leaflet throughout the systolic phase. The UCG findings of this holosystolic anterior mitral leaflet prolapse in this case are as follows: 1) The small echo behind anterior leaflet in early systole (UCG-2). 2) Three echoes in the latter half of systole (UCG-3). 3) Midsystolic buckling (UCG-4). The course of systole proceeds in order of A, B, and C. ª: prolapse, ö: midsystolic buckling, AML: anterior mitral leaflet, Pan: posterior mitral annulus, N: notch, LAW: left atrial wall, LVW: left ventricular wall.

5 Vol.19 No.2 UCG OF PROLAPSED MITRAL VALVE 179 Fig.2. Holosystolic prolapse of anterior mitral leaflet. The same case as in Fig.1. This figure was obtained on a different section of the heart from that in Fig.1. The prolapse of anterior leaflet is not as markedly documented as in Fig.1. The early systolic (UCG-1) and holosystolic (UCG-2, 3) linear echoes ahead of anterior mitral leaflet come from chordae tendineae. ª: prolapse, Chr: chordae tendineae, AML: anterior mitral leaflet, Pan: posterior mitral annulus, LAW: left atrial wall, LVW: left ventricular wall. anterior mitral leaflet was not as remarkable as in Fig.1. B) Midsystolic prolapse Fig.3 shows a case with midsystolic click and late systolic murmur.

6 180 TERASAWA ET AL Jap. Heart J. March, 1978 Fig.3. The anterior mitral leaflet prolapse in midsystole. A 6-year-old boy had midsystolic click and late systolic murmur. Anterior mitral leaflet began to prolapse in midsystole on UCT and midsystolic buckling indicated the beginning of the prolapse in midsystole on UCG (UCG-2, 3). ö: midsystolic buckling, ª: prolapse. Midsystolic buckling was found on UCG and the prolapse of anterior leaflet after midsystole was found on UCT. The case shown in Fig.4 had midsystolic click and late systolic murmur. The prolapse of posterior leaflet was detected by left ventriculography (Fig.5). As shown by UCT, it was the anterior leaflet that showed the prolapsing movement at midsystole (Fig.4 and UCT-3) and then the leaflet reached the position of maximal prolapse (Fig.4, UCT-4 and Fig.7-UCT). On UCG it was found that midsystolic buckling was related to the prolapse of anterior leaflet (Fig.4 UCG-2, Fig.6-3, 4 and Fig.7-2). At time of the maximum amplitude of unusual early systolic anterior motion (early SAM) of chordae tendineae, the anterior leaflet had already begun to prolapse (Fig.4-UCG-2 and Fig.6-3, 4). The early SAM was caused by the elongated chordae tendineae (Fig.4). The echoes of midsystolic buckling in the latter half of systole came

7 Vol.19 No.2 UCG OF PROLAPSED MITRAL VALVE 181 Fig.4. UCT of the anterior mitral leaflet prolapse in midsystole and the echo source of the early SAM. A 35-year-old man, had midsystolic click and late systolic murmur. The chordae tendineae protruded gradually toward left ventricular outflow tract and approached ventricular septum in midphase (UCT-3). The early SAM is caused by the slackened elongated chordae tendineae (UCG-2). Two or 3 echoes in early SAM (UCG-2) was confirmed by UCT that the upper 1 or 2 echoes came from the chordae tendineae and the lower one from the anterior mitral leaflet. The midsystolic buckling of chordae tendineae is of minor magnitude and does not indicate the prolapse itself and the buckling of the anterior leaflet is larger than that of chordae tendineae. The course of systole is in order of 1 to 5. ª : anterior mitral leaflet prolapse, ö: elongated chordae tendineae, AML: anterior mitral leaflet. from the chordae tendineae (upper echo) and from the anterior leaflet (lower echo) (Fig.4-UCG-2 and Fig.6-3, 4). In the basal portion of anterior leaflet, the early SAM, the amplitude of which was very small, appeared abruptly in systole, because the tip of the slackened elongated chordae tendineae protruded toward left ventricular outflow tract (Fig.6-2). In the more apical portion of the elongated chordae tendineae, the early SAM which seemed to be in continuity with the echo from anterior leaflet

8 182 TERASAWA, ET AL Jap. HeartJ. M arch, 1978 Fig.5. Left ventriculogram of the prolapse of the anterior mitral leaflet. The same case as in Fig.4. On the UCT the prolapse of the anterior leaflet is demonstrated. But the prolapse is found to be that of the posterior leaflet with reference to the left ventriculography. appeared earlier in systole than the early SAM of the basal portion (Fig.6-2 `5 ). The hump or the 2 echoes at the basal portion of anterior leaflet in late systole was related to the protrusion of the tip of chordae tendineae or to the protruding tip of chordae tendineae and anterior leaflet (Fig.4-UCG 1 and Fig.6-1). II. Prolapse of posterior mitral leaflet Fig.8 shows a case of rheumatic mitral regurgitation. The prolapse of posterior leaflet was found only in early systole (Fig.8-A). The UCT showed dilatations of left atrium and of left ventricle, thickened mitral valve and chordae tendineae, and bulging of anterior leaflet toward left atrium in systole with a direction opposite to that in healthy individuals.46),47) The UCG findings of the prolapse of posterior leaflet were as follows. A) A small echo behind anterior leaflet in early systole (Fig.8-2) In early systole the ultrasonic beam hit against the prolapsing portion of posterior leaflet (Fig.8-A and 2). During the course of systole, however, it became impossible for the beam to hit against the prolapsing portion, because mitral valve moved downward. B) Two echoes behind anterior leaflet in systole (Fig.8-3)

9 Vol.19 No.2 UCG OF PROLAPSED MITRAL VALVE 183 Fig.6. UCG of the anterior mitral leaflet prolapse in midsystole. The same case as in Figs.4 and 5. The midsystolic buckling of the anterior leaflet has already begun to prolapse at the maximum height of the early SAM (UCG 3 and 4). The abrupt appearance of the small early SAM is due to the protruding tip of chordae tendineae against which the ultrasonic beam hits (UCG-2). Multiple echoes within the early SAM are recorded because the beam hits against the elongated chordae tendineae almost at the right angle (UCG-3, 4). The amplitude and the timing of the occurrence of the early SAM is larger and earlier toward the apex than at the basal part. The maximum amplitude and downward ratio of the early SAM is 3cm and 350mm/sec respectively. Such values are almost equal to the mobile range and the closing rate of normal anterior leaflet. The small hump or the 2 echoes in late systole are caused by the protruding chordal tip or the protruding tip of chordae tendineae and anterior leaflet (UCG-1). Chr: chordae tendineae, AML: anterior mitral leaflet, ª: anterior mitral leaflet prolapse, ö : elongated chordae tendineae, ö: midsystolic buckling. In early systole the ultrasonic beam hit against posterior leaflet twice (Fig. 8-A and 3). Thus 2 echoes of posterior leaflet were found on UCG (Fig.8-3). In pansystolic prolapse, 2 echoes of posterior leaflet were also found on UCG (Fig.9-1). Thus, the prolapse of posterior leaflet and ballooning

10 184 TERASAWA, ET AL Jap. HeartJ. M arch, 1978 Fig.7. The UCG findings of the anterior leaflet prolapse. This figure is the same case as in Figs.4, 5, and 6, and was obtained at a different section from that in Fig.6. The early SAM shown in UCG-2 has been reported in no small numbers and indicates elongated chordae tendineae. Chr: chordae tendineae, AML: anterior mitral leaflet, ª: prolapse. of anterior leaflet (Fig.8 and Fig.9-2) could be detected on UCG. But by UCG alone it was extremely difficult to detect posterior leaflet prolapse. III. Double mitral leaflet prolapses Fig.10 shows a case of the prolapses of both mitral leaflets due to papillary muscle dysfunction. No murmur was heard, probably because there was no mitral regurgitation. In this case both leaflets took a symmetrical position in prolapse, and there was incidentally good coaptation of the leaflets. The findings of the prolapse observed in UCT could not, however, be detected on UCG. DISCUSSION The prolapsed mitral valve has been found in association with Marfan syndrome,13),34) coronary heart disease,9) papillary muscle dysfunction,10)

11 Vol.19 No.2 UCG OF PROLAPSED MITRAL VALVE 185 Fig.8. The posterior mitral leaflet prolapse. The posterior leaflet prolapse in early systole and the ballooning of anterior leaflet in systole arc shown and then the prolapse of posterior leaflet disappears in late systole. The prolapse findings shown on UCG are a little echo behind anterior leaflet in early systole (UCG-2) and the 2 echoes behind anterior leaflet in systole (UCG-3). The former finding is difficult to discriminate from the anterior leaflet prolapse itself as shown in Fig.1-1. The latter is based on 2 penetrations of the prolapsed part. The ballooning of anterior leaflet could not be detected on UCG. The systolic phase progress is shown in order of A, B, C. AML: anterior mitral leaflet, ª: prolapse, ö: ballooning of anterior mitral leaflet, PML: posterior mitral leaflet, LVW: left ventricular wall, LAW: left atrial wall. rheumatic mitral regurgitation,1),2),31) and atrial septal defect.33),34) Midsystolic click and late systolic murmur have been found in many of these cases. Criley10) and Barlow2) reported that the prolapse of posterior mitral leaflet was found in the syndrome of midsystolic click and late systolic murmur.

12 186 TERASAWA, ET AL Jap. HeartJ. M arch, 1978 Fig.9. Posterior mitral leaflet prolapse. 1 shows holosystolic prolapse of posterior leaflet and 2 shows ballooning of anterior leaflet. These 2 cases had rheumatic mitral regurgitation. The prolapse of posterior leaflet is indicated by the presence of 2 echoes behind anterior leaflet. Thus the prolapse of posterior leaflet and the anterior ballooning are not difficult to detect by UCG alone. AML: anterior mitral leaflet, PML: posterior mitral leaflet, ª: prolapse ö: ballooning of anterior mitral leaflet. Since then numerous publications have dealt with the relationship between the prolapse of the mitral leaflet and phonocardiographic findings. In 1970 Shah and Gramiak reported the availability of UCG for the detection of the prolapse of mitral valve.17) The works of Dillon,18) Burgess,19) Demaria,23) Popp,21) Cohen,26) and Malcolm32) were concerned with the same problem, in particular with the prolapse of posterior leaflet. Identification of the anterior and posterior leaflets has mainly been from the findings of left ventriculography 10),18),19),21),23),25),26) The echo source on UCG of the prolapsed leaflet, however, has never been confirmed. Namely it has remained undecided on UCG that which of it was the anterior or the posterior leaflet was protruding from mitral apparatus. The present authors examined the findings characteristic of the prolapse of mitral leaflets on UCG. By using UCG in combination with UCT the echo of anterior leaflet could be distinguished from that of posterior leaflet and from that of chordae

13 Vol.19 No.2 UCG OF PROLAPSED MITRAL VALVE 187 Fig.10. Both anterior and posterior mitral leaflet prolapses. This case was thought to have papillary muscle dysfunction as a result of myocardial infarction. Prolapses of both leaflets are found on UCT, but not on UCG. Because the prolapse was of minor degree, the beam did not always hit against the prolapsing portion due to the downward movement of mitral valve in systole. ª: prolapse, Chr: chordae tendineae, AML: anterior mitral leaflet, PML: posterior mitral leaflet, Pan: posterior mitral annulus, LAW: left atrial wall, LVW: left ventricular wall. tendineae. A) Echo sources on UCG of the prolapsed mitral valve and the relationship between the findings of UCG and those of left ventriculography. Up to the present, differentiation of the echo of anterior leaflet from that of posterior leaflet on UCG has been based on the findings of left ventriculography.10)-15),34) It seems that the echo in front has been simply assigned to anterior leaflet and that in the rear to posterior leaflet.18),21) The cases as shown in Figs. 1, 2, 3, 4, 6, and 7 were found to have a prolapsed leaflet on UCT. These cases would have been grouped under the category of the prolapse of posterior leaflet, if analysis was made by left ventriculography alone. Provided that the interpretation based on the

14 188 TERASAWA, ET AL Jap. Heart J. March, 1978 findings on UCT is erroneous, then it follows that the characteristic diastolic pattern on UCG of the prolapsing and the non-prolapsing portions of anterior leaflet cannot be assigned to the anterior leaflet. Such a possibility seems to be very remote. On the other hand, by using left ventriculography alone, the prolapse of posterior leaflet toward left atrium might be interpreted as that of anterior leaflet. The midsystolic buckling shown in Figs.3, 4, 6, and 7 has hitherto been ascribed to the prolapse of posterior leaflet. 18),21),23),26),33) However these findings, as evidenced in our study, are consistent with the prolapse of anterior leaflet. It was found that the echo in front came from chordae tendineae and the echo in the rear came from anterior leaflet. The cases presented here indicate clearly that it is very important to identify the echo source and that the diagnosis of prolapsed mitral valve based on the findings of cineangiocardiography alone may be equivocal. There is a possibility that the prolapse of posterior leaflet found on cineangiocardiography may prove, after all, to be that of anterior leaflet. Thus considered, the results of cineangiocardiography obtained up to the present seem to require reevaluation. The authors have experienced 2 cases of midsystolic click and late systolic murmur and 3 cases of pansystolic murmur with late accentuation and without a click. In all 3 cases, the prolapse of posterior leaflet diag nosed by left ventriculography was found by UCT to be that of anterior leaflet. It has been reported that the prolapse of mitral leaflet occurs mainly in the posterior leaflet. On the other hand, our results suggest that the echoes from chordae tendineae have been interpreted as those of anterior leaflet and the echoes of anterior leaflet as those of posterior leaflet. Thus it is clear that ultrasono-cardiotomography in combination with ultrasonocardiography is better than cineangiocardiography for the detection of the prolapsed mitral valve. B) Prolapse of anterior mitral leaflet As a characteristic finding of the prolapse of anterior mitral leaflet on UCG, midsystolic buckling was found in all of our cases. 18),21),23),26),32) Since midsystolic buckling was found in cases of both pansystolic and midsystolic prolapse, it was difficult to determine the timing of the onset of prolapse when evaluation was based on one sheet of UCG alone. In our cases of pansystolic prolapse, 3 echoes were found in the latter half of systole in addition to a small echo behind anterior leaflet in early systole (Fig.1). But the linear echo ahead of anterior leaflet came from chordae tendineae as shown in Fig.2 (Fig.2-2 and 3). These anterior leaflet

15 Vol.19 No.2 UCG OF PROLAPSED MITRAL VALVE 189 echoes have been confused with those from chordae tendineae. Hence, for the precise diagnosis of the pansystolic prolapse of anterior leaflet, it is necessary to distinguish the echoes of anterior leaflet from those of chordae tendineae (Figs.1, 2, 4, and 6). However, the distinction of anterior leaflet from chordae tendineae by UCG alone is extremely difficult. Also a midsystolic notch (Fig.1-4) and early SAM which is caused by elongation of chordae tendineae (Figs.4, 6, and 7) are significant, although they are indirect findings of the prolapse. It is possible for midsystolic buckling to show various patterns of echo depending on the following factors: 1) downward movement of the mitral leaflets in systole, 2) degree of the prolapse, and 3) timing of the occurrence and change in the pattern of prolapse during the course of systole. Also the notch in systole may show several different patterns depending on the extent of the prolapse, on the downward movement of mitral leaflets, and on the forward movement of anterior leaflet as a result of left atrial enlargement in systole. Identification by UCG alone of the systolic bulging (or ballooning) of anterior leaflet, which is found mainly in cases of rheumatic mitral regurgitation, is impossible (Figs.7 and 8). C) Prolapse of posterior mitral leaflet In our study, the prolapse of posterior leaflet was found mainly in cases of rheumatic mitral regurgitation with organic lesions of the mitral valve. The present authors have experienced that the prolapse of posterior leaflet was also found not infrequently in cases of mitral stenosis. In patients with the so-called midsystolic click and late systolic murmur syndrome, the prolapse of posterior leaflet has never been observed in our study. In the prolapse of posterior leaflet, there were 1 small echo in early systole and 2 linear echoes behind anterior leaflet in systole (Fig.8 and 9-1). The small echo appeared because the prolapse occurred only in early systole. The latter 2 linear echoes appeared because twice in systole the ultrasonic beam hit against the upper portion of the prolapsing or protruding of posterior leaflet toward left ventricle. Consequently it was almost impossible to confirm the prolapse of posterior leaflet by UCG alone without UCT, although in reality there was direct evidence of the prolapse of posterior leaflet on UCG. D) Double mitral leaflet prolapses There will, of course, be additional characteristics in the findings on the UCG of the prolapses of anterior and posterior leaflets. In our study there were no findings indicative of the characteristics of the prolapse of the 2 leaflets, because the extent of forward excursion of anterior leaflet due to the enlarge-

16 190 TERASAWA, ET AL Lap. March, Heart 1978 J. ment of the left atrium was more remarkable than the degree of prolapse of leaflet and the ultrasonic beam did not always hit against the prolapsing portion due to the downward movement of mitral valve in systole (Fig.10). On the other hand, the prolapse of posterior leaflet also could not be detected on UCG because the extent of the downward motion was more remarkable than that of the prolapse of anterior leaflet. Therefore it was impossible to determine the echo sources and to discover findings characteristic of double mitral prolapses. Pansystolic bowing which is found in the case of prolapse throughout the systolic phase has not been found in the present investigation. Ultrasono-cardiotomography is one of the most precise methods available for the detection of the prolapsed mitral valve. When echo sources are identified by the UCT in a preliminary investigation, UCG will become a more refined diagnostic tool of the prolapse of mitral valve. ACKNOWLEDGEMENTS We thank Miss B.M. McCoy of Shokei Girls School and Dr. M.Motomiya, Assoc. Prof. of this Institute, for their helpful advices improving the English. REFERENCES 1. Barlow JB, Pocock WA, Marchand P, Denny M: The significance of late systolic murmurs. Am Heart j 66: 443, Barlow JB, Bosman CK, Pocock WA, Marchand P: Late systolic murmurs and non-(midlate) systoliclicks. Brit Heart J 30: 203, Reid JVO: Midsystolic click. South Afr Med J 35: 353, Fontana M, Pence HL, Leighton RF, Wooley CF: The varying clinical spectrum of the systoliclick-late systolic murmur syndrome. Circulation 41: 807, Epstein EJ, Coulshed N: Phonocardiogram and apex cardiogram in systoliclick-late systolic murmur syndrome. Brit Heart J 35: 26, Jeresaty RM: Etiology of the mitral valve prolapse-click syndrome. Am J Cardiol 36: 110, Jeresaty, RM: The syndrome associated with midsystolic click and/or latsystolic murmur. Analysis of 32 cases. Chest 59: 643, Dock W: Production mode of systoliclicks due to mitral cusp prolapse. Arch Int Med 131: 118, Lewis HP: Midsystolic clicks and coronary heart disease. Circulation 44: 493, Criley JM, Leweis KB, Humphries JO, Ross RS: Prolapse of the mitral valve. Clinical and cineangiocardiographic findings. Brit Heart J 28: 488, Kittredge RD, Shimomura S, Cameron A, Bell ALL: Prolapsing mitral valve leaflets. Cineangiographic demonstration. Am J Roentgenol 109: 84, Jeresaty RM: Ballooning of the mitral valve leaflets. Radiology 100: 45, Jeresaty RM: Mitral valve prolapse-click syndrome. Prog Cardiovasc Dis 15: 623, Scampardonis G, Yang SS, Maranhao V, Goldberg H, Gooch A: Left ventricular abnormalities in prolapsed mitraleaflet syndrome. Circulation 48: 287, 1973

17 Vol.19 No.2 UCG OF PROLAPSED MITRAL VALVE Ranganathan N, Silver MD, Robinson TI, Kostuk WJ, Felderhof CH, Patt NL, Wilson JK, Wigle ED: Angiographic-morphologic correlation in patients with severe mitral valve leaflet. Circulation 48: 514, Fontana ME, Wooley CF, Leighton RF, Lewis RP: Postural changes in left ventricular and mitral valvular dynamics in the sytolic click-late systolic murmur syndrome. Circulation 51: 165, Shah PM, Gramiak R: Echocardiographic recognition of mitral valve prolapse. Circulation 42: 111, Dillon JC, Haine CL, Chang HS, Feigenbaum H: Use of echocardiography in patients with prolapsed mitral valve. Circulation 43: 503, Burgess J, Clark R, Kamigaki M, Cohn K: Echocardiographic findings in different types of mitral regurgitation. Circulation 48: 97, Spencer WH, Behar FVS, Orgain ES: Apex cardiogram in patients with prolapsing mitral valve. Am J Cardiol 32: 276, Popp RL, Brown O, Silverman JF, Harrison DC: Echocardiographic abnormalities in the mitral valve prolapse syndrome. Circulation 49: 428, Allen H, Harris A, Leatham A: Significance and prognosis of an isolated late systolic murmur. A 9 to 22 year follow up. Brit Heart J 36: 525, Demaria AN, King JF, Bogreen HG, Lies J, Mason DT: The variable spectrum of echocardiographic manifestation of the mitral valve prolapse syndrome. Circulation 50: 33, Brown OR, DeMots H, Kloster FE, Roberts A, Denashe VD, Belas RK: Aortic root dilatation and mitral valve prolapse in Marfan's syndrome. Circulation 52: 651, Weiss AN, Minbs JW, Ludbrook PA, Sobel BE: Echocardiographic detection of mitral valve prolapse. Exclusion of false positive diagnosis and determination of inheritance. Circulation 52: 1091, Cohen MV: Double mitral leaflet prolapse. Echocardiographic-phonocardiographic correlation. Am Heart J 91: 168, Goodman D, Kimbiris D, Linhart JW: Chordae tendineae rupture complicating the systolic click-late systolic murmur syndrome. Am J Cardiol 33: 681, Nutter DO, Wickliffe C, Gilbert CA, Moody C, King SB III: The pathophysiology of idiopathic mitral valve prolapse. Circulation 52: 297, Marchand P, Barlow JB, Plessis LA, Webster I: Mitral regurgitation with rupture of normal chordae tendineae. Brit Heart J 28: 746, Tempo CPB, Ronan JA, Leon AC, Twigg HL: Radiographic appearance of the thorax in systolic click-late systolic murmur syndrome. Am J Cardiol 36: 27, Steinfeld L, Dimichi I, Rappaport H, Baron M: Late systolic murmur of rheumatic mitral insufficiency. Am J Cardiol 35: 397, Malcolm AD, Boughner DR, Kostuk WJ, Ahuja S: Clinical features and investigatative findings in presence of mitral leaflet prolapse. Study of 85 consecutive patients. Brit Heart J 38: 244, MacDonald A, Harris A, Jefferson K, Marshall J, MacDonald L: Association of prolapse of posterior cusp of mitral valve and atrial septal defect. Brit Heart J 33: 383, Devereux RB, Perloff JK, Reichek N, Josephson ME: Mitral valve prolapse. Circulation 54: 3, Bitter N, Sosa JA: The billowing mitral valve leaflet. Report on fourteen patients. Circulation 38: 763, Ebina T, Oka S, Tanaka M, Kosaka S, Uchida R, Hagiwara Y: The diagnostic application of ultrasound to disease in mediastinal organs. Ultrasono-tomography for the heart and great vessels (the first report). 12: 199, 1965 Science Reports of the Research Institute, Tohoku Univ-C 37. Ebina T, Oka S, Tanaka M, Kosaka S, Terasawa Y, Unno K, Kikuchi Y, Uchida R: The ultrasono-tomography for the heart and great vessels in living human subjects by means of

18 192 TERASAWA, ET AT Jap. HeartJ. M arch, 1978 the ultrasonic reflection technique. Jap Heart J 8: 331, Tanaka M, Neyazaki T, Kosaka S, Oka S, Ebina T, Terasawa Y, Unno K, Nitta K: Ultrasonic evaluation of anatomical and heart diseases. Brit Heart J 33: 686, Kikuchi Y, Okuyama D, Tanaka M, Kosaka S, Terasawa Y: Ultrasono-cardiotomographical analysis of the mitral valve movement. Ultrasono Graphia Medica III (Proceeding of the 1st Congress on Ultrasonics in Medicine and Siduo III, Vienna, Austria 1969), Verlag der Wiener Medizinischen Akademie, Wien, p , Kikuchi Y, Okuyama D, Tanaka M, Ebina T, Oka S: Ultrasono-cardiotomography and its application to morphological measurement of the heart. Ultrasono Graphia Medica III, Verlag der Wiener Medizinishen Akademie, Wien, p475, Tanaka M, Kosaka S, Terasawa Y, Unno K, Sugi H: Clinical significance of the ultrasonic method fot the morphological and functional measurement of the circulatory organs. Heart 2: 119, 1970 (in Japanese) 42. Tanaka M, Oka S, Ebina T, Terasawa Y, Unno K, Kikuchi Y, Kasai C, Uchida R, Hagiwara Y: Ultrasonotomography of the heart and great vessels in living human subject. Medical Ultrasonics 4: 47, Tanaka M, Oka S, Kikuchi Y, Okuyama D, Ebina T, Kosaka S, Terasawa Y, Unno K, Uchida R, Hagiwara Y: Improvement in quality of the tomographic pattern by applying a STC device. Medical Ultrasonics 5: 49, Tanaka M, Oka S, Kikuchi Y, Okuyama D, Kasai C, Ebina T, Kosaka S, Terasawa Y, Unno K, Uchida R: The effects of FTC (fast time constant) circuit on ultrasonotomography. Medical Ultrasonics 6: 131, Tanaka M, Oka S, Kikuchi Y, Okuyama D, Ebina T, Kosaka S, Terasawa Y, Unno K, Uchida R, Hagiwara Y: Ultrasonocardiotomography (8th report) in which the scanning plane of transducer is stereotaxic with regard to the body surface of the subject. Medical Ultrasonics 6: 52, Tanaka M, Kosaka S, Oka S, Okuyama D, Kasai C, Ebina T, Terasawa Y, Unno K, Nitta K: Ultrasono-cardiotomography (13th report). The analysis of the movement of the mitral valve by ultrasono-cardiotomography. Medical Ultrasonics 7: 36, Terasawa Y: Studies on analysis of the mitral valve movement by means of ultrasonocardiotomography. Kosankinbyo Kenkyu Zasshi 23: 73, 1971 (in Japanese) 48. Tanaka M, Kosaka S, Oka S, Terasawa Y, Unno K, Nitta K, Ebina T: Mitral valve movements in mitral valvular disease by ultrasono-cardiotomography (Ultrasono-cardiotomography, 19th report). Reports of the 18th Scientific Meeting of Japanese Ultrasonic Medical Society p53, 1970 (in Japanese) 49. Tanaka M, Kosaka S, Konno K, Terasawa Y, Nitta K, Hikichi H, Ebina T: Movements of the prolapsed mitral valve (Ultrasono-cardiotomography, 30th report). Reports of the 27th Scientific Meeting of Japanese Ultrasonic Medical Society p227, 1975 (in Japanese)