Time analysis of mitral regurgitation in patients with mitral valve prolapse: a study by phonocardiography and Doppler techniques

To assess the timing and duration of mitral regurgitation (MR) in patients with mitral valve prolapse (MVP), 20 subjects with mid-systolic click(s) and/or a late systolic murmur were studied using phonocardiography, two-dimensional echocardiography (2DE) and Doppler techniques including pulsed Doppler (PD), high pulse repetition frequency Doppler (HPRF), continuous wave Doppler (CW) and M-mode color Doppler (MD) methods and two-dimensional Doppler color flow mapping (2DD). The results were compared with those of 16 patients with a pansystolic murmur having late systolic accentuation. MVP with MR was observed in 15 of the 20 patients with mid-systolic clicks and/or a late systolic murmur and in all of the 16 patients with a pansystolic murmur. Using MD, MR signals were seen throughout systole and isovolumic relaxation period in all but one of these patients, and they were not related to the patterns of the systolic murmur. In only one, an MR signal was recorded just after the click. Five patients with a mid-systolic click lacked the findings of MVP, but two of them had MR signal only in early systole. Using PD and HPRF techniques, the timing and duration of MR signals in patients with mid-systolic clicks and/or a late systolic murmur were varied by changing the sites of the sample volume. Similarly, the timing and duration of MR signals in these patients were dependent on the ultrasonic beam direction by the CW method. In most patients with a pansystolic murmur having late systolic accentuation, however, MR signals throughout systole and the isovolumic relaxation period were demonstrated by each Doppler method. Therefore, PD, HPRF, and CW were not so efficiently sensitive or adequate techniques for investigating the timing and duration of MR, especially in patients with mid-systolic clicks and/or a late systolic murmur, who had mild or eccentric MR jets. In conclusion, 1) MR in MVP involves the entire systole and isovolumic relaxation period, 2) PD, HPRF and CW methods are not adequate for detecting mild or eccentric MR jets in patients with mid-systolic clicks and/or a late systolic murmur, and 3) MD is useful for the time analysis of MR in these patients.     

Temporal resolution of mitral regurgitation in patients with mitral valve prolapse: a phonocardiographic and Doppler echocardiographic study

To assess the timing and duration of mitral regurgitation in mitral valve prolapse, 20 patients with a mid-systolic click or late systolic murmur, or both (Group 1) and 16 patients with a pansystolic murmur with late systolic accentuation (Group 2) were studied with phonocardiography and echocardiography including various Doppler techniques. The subjects' ages ranged from 15 to 73 years. Mitral valve prolapse with mitral regurgitation was observed in 15 of 20 patients in Group 1 and in all 16 patients in Group 2. M-mode Doppler color echocardiography demonstrated a mitral regurgitant signal throughout systole and isovolumic relaxation in all but 1 of these 31 patients regardless of the pattern of the systolic murmur. The regurgitant signal was recorded after the click in only one patient with mitral valve prolapse in Group 1. Two of the five patients in Group 1 without two-dimensional echocardiographic findings of mitral valve prolapse had the early systolic signal of mitral regurgitation. The timing and duration of the mitral regurgitant signal detected in patients in Group 1 with pulsed or continuous wave Doppler ultrasound varied with the site of the sample volume or beam direction. In the patients in Group 2, however, the signal was demonstrated throughout systole and isovolumic relaxation by both Doppler methods. Compared with M-mode Doppler color echocardiography, therefore, pulsed and continuous wave Doppler methods were less sensitive and thus inadequate to investigate the timing and duration of mitral regurgitation in mitral valve prolapse, especially in patients with a mid-systolic click or a late systolic murmur, or both, who had mild or eccentric mitral regurgitant jets.(ABSTRACT TRUNCATED AT 250 WORDS)     

Double mitral leaflet prolapse: echocardiographic-phonocardiographic correlation.

Ten per cent of all patients referred to the echocardiography laboratory for diagnostic evaluation had mitral valve prolapse. Of these 35 patients, 19 (54 per cent) had prolapse of both the anterior and posterior mitral leaflets. Of the 19 patients, 13 had Type A or midsystolic prolapse, whereas six had Type B or pansystolic prolapse of the mitral leaflets. Simultaneous phonocardiographic examination of the patients revealed either midsystolic click and late systolic murmur, pansystolic murmur, or isolated click and short systolic murmur. There was no apparent correlation between the echocardiographic prolapse pattern and the auscultatory events. One patient with Type A prolapse had no auscultatory abnormalities at the time of the examination. It is suggested that the abnormal sounds may be generated by a redundant mitral leaflet rather than chordae tendineae.     

Observer variation in the echocardiographic diagnosis of mitral valve prolapse

To assess inter- and intraobserver variation in the echocardiographic diagnosis of mitral valve prolapse, three independent observers analyzed M-mode echocardiograms (n = 80) and two-dimensional echocardiograms (n = 65) of patients with a mobile midsystolic click with or without a late or holosystolic murmur. In addition, a control group of 100 normal echocardiograms were interspersed among the echocardiograms of patients with mitral valve prolapse and were then interpreted. Each of the three observers analyzed all M-mode and two-dimensional echocardiograms initially and then 2 weeks later for the presence or absence of mitral valve prolapse. M-mode echocardiographic criteria for mitral valve prolapse consisted of late systolic posterior motion (greater than or equal to 3 mm) of one or both mitral leaflets or holosystolic hammocking (greater than or equal to 3 mm) of one or both mitral leaflets. Two-dimensional echocardiographic criteria for mitral valve prolapse consisted of: posterior systolic arching of one or both mitral leaflets in the parasternal long-axis view, and/or posterior systolic bowing of one or both mitral leaflets in the apical four-chamber view posterior to the plane of the mitral anulus, and/or excessive posterior coaptation of the mitral leaflets in either view flush with or posterior to the plane of the mitral anulus. There was insignificant observer variation both in the M-mode and two-dimensional echo groups, as determined using Cochran's Q test.(ABSTRACT TRUNCATED AT 250 WORDS)     

Incidence of ruptured chordae tendineae in the mitral valvular prolapse syndrome: an echocardiographic study.

Echocardiographic studies were performed in 190 consecutive patients with mitral valvular prolapse. All patients had either midsystolic posterior motion of the mitral valve or holosystolic hammock-like movement of the valve in systole. Thirteen patients (7 percent) were noted to have ruptured chordae tendineae. In four patients, a combination of abnormalities was observed. Five patients had clinical and bacteriologic evidence of infective endocarditis, two of whom had severe intractable pulmonary edema consequent to acute mitral regurgitation which required mitral valvular replacement. At surgery, one of these patients had ruptured chordae tendineae to both leaflets, and the other had chordal rupture of the posterior leaflet. The other patients probably had spontaneous rupture of the chordae tendineae. A spectrum of clinical findings was noted. Six patients had marked mitral regurgitation, while two had isolated systolic clicks. Thus, chordal rupture does not always result in severe hemodynamic deterioration. Serial echocardiographic studies will be of value in studying the natural history and progression of disease in patients with chordal rupture.     

The significance of mitral valve prolapse in middle-aged and elderly men.

The clinical, roentgenographic, phonocardiographic, ECG, and echocardiographic data were evaluated in 40 consecutive middle-aged and elderly male patients with echocardiographically detectable systolic prolapse of mitral valve leaflets. Prolapse was present during more than half of systole in 31 patients and was holosystolic in six patients. In most instances, both leaflets prolapsed during systole. The closing velocity and excursion of the anterior leaflet were frequently increased particularly in association with evidence of mitral insufficiency. A majority of the patients had cardiac symptomatology. Moreover, roentgenographic and/or ECG evidence of cardiac enlargement or hypertrophy was evident in 45 percent of patients with mitral valve prolapse.     

Systolic closure of aortic valve in patients with prosthetic mitral valves.

Systolic closure of the aortic valve was found in 10 of 36 patients who underwent mitral valve replacement. Eight patients had early systolic closure, and two had mid-systolic closure. The left ventricular outflow tract dimension on M-mode and two dimensional echocardiograms, left ventricular posterior wall and septal thickness, left ventricular dimensions in systole and diastole, aortic valve opening, and mitral to aortic valve distance were not significantly different between patients with and without systolic closure of the aortic valve. Two of the 10 patients with systolic aortic valve closure were catheterised and in neither was there a gradient between the left ventricle and the aorta. The two patients with mid-systolic closure, however, were the patients who had the narrowest left ventricular outflow tract which could cause significant distortion of blood flow. Systolic closure of the aortic valve in patients with mitral valve replacement is probably not caused by left ventricular outflow tract obstruction, though abnormalities in laminar flow from the left ventricular outflow tract may be involved.     

Abnormal motion of the mitral valve with pericardial effusion: Pseudo-prolapse of the mitral valve.

The echocardiograms of seven patients with large pericardial effusions were found to show posterior motion of the mitral leaflets in systole as seen in prolapse of the mitral valve. Repeat echocardiograms after resolution of the effusion revealed normal mitral valve motion. None of the patients had clinical evidence of prolapsed mitral valve. We postulate that a posterior swing of the heart within the pericardial fluid occurring in late systole causes posterior displacement of the mitral valve simulating a prolapsed valve.     

Pulsed Doppler echocardiographic evaluation of valvular regurgitation in patients with mitral valve prolapse: comparison with normal subjects

Pulsed Doppler echocardiography was used to determine prospectively the prevalence of mitral, aortic, tricuspid and pulmonary regurgitation in 80 consecutive patients with mitral valve prolapse and 85 normal subjects with similar age and sex distribution. Mitral valve prolapse was defined by posterior systolic displacement of the mitral valve on M-mode echocardiography of 3 mm or more (40 patients), the presence of one or more mid- or late systolic clicks (61 patients), or both. Mitral regurgitation, detected by pulsed Doppler techniques in 53 patients with prolapse, was holosystolic in 24, early to mid-systolic in 6, late systolic in 15 and both holosystolic and late systolic behind different portions of the valve in 8. Definitive M-mode findings were present in only 27 of the 53 patients, and only 21 had mitral regurgitation audible on physical examination. Tricuspid regurgitation was evident by pulsed Doppler echocardiography in 15 patients (holosystolic in 9, early to mid-systolic in 1, late systolic in 4 and both holosystolic and late systolic in 1); 12 of these 15 patients, including all with an isolated late systolic pattern, had an echocardiographic pattern of tricuspid prolapse, but none had audible tricuspid regurgitation. A Doppler pattern compatible with aortic regurgitation was recorded in seven patients, all without echocardiographic aortic valve prolapse and only two with audible aortic insufficiency. A Doppler shift in the right ventricular outflow tract in diastole, suggestive of pulmonary regurgitation, was recorded in 16 of the 78 patients with an adequate Doppler examination: only 1 of the 16 had audible pulmonary insufficiency. Of the 85 normal subjects without audible regurgitation, pulsed Doppler examination detected mitral regurgitation in 3 subjects (holosystolic in 1 and early to mid-systolic in 2), aortic regurgitation in none, tricuspid regurgitation in 9 (holosystolic alone in 8 and both holosystolic and late systolic in 1) and right ventricular outflow tract turbulence compatible with pulmonary insufficiency in 15. The prevalence of valvular regurgitation, detected by pulsed Doppler echocardiography, is high in patients with mitral valve prolapse. Regurgitation may involve any of the four cardiac valves and is clinically silent in the majority of patients. The prevalence rates of mitral and aortic regurgitation are significantly higher in patients with mitral prolapse than in normal subjects, suggesting that alterations in underlying valve structure in the prolapse syndrome may indeed be responsible for this regurgitation.(ABSTRACT TRUNCATED AT 400 WORDS)     

Late systolic murmur of rheumatic mitral insufficiency

Of 184 patients with acute rheumatic fever and associated mitral insufficiency encountered during a 15 year period, 34 manifested a mid-late systolic murmur or a nonejection click, or both, during the course of follow-up.The mid-late systolic murmur later disappeared in four patients whose condition is now considered normal. In one of the four, systolic prolapse of the mitral valve was demonstrated on an angiocardiogram obtained when the systolic murmur was present. Since disappearance of the murmur there has been no evidence of systolic prolapse on meticulous echocardiographic study of the mitral valve. In another child with angiographically demonstrated systolic prolapse of the mitral valve the systolic murmur has also disappeared, but systolic prolapse is still evident on echocardiographic study.None of the 34 patients with a mid-late systolic murmur manifested the T wave abnormalities commonly associated with the familial variety of mitral valve prolapse.     

Cross-sectional echocardiographic detection of rheumatic mitral regurgitation

Short-axis, cross-sectional echocardiograms of the mitral valve were performed in 20 consecutive patients with rheumatic mitral valve disease to determine if mitral regurgitation could be detected. In four patients, cross-sectional echocardiograms were technically inadequate. Of the 16 remaining patients, 8 had no significant mitral regurgitation on cineangiography, and 8 had significant regurgitation. Two independent observers reviewed videotapes of the cross-sectional echocardiograms without knowledge of the cineangtograms or clinical findings. In each case, the presence of significant mitral regurgitation was correctly predicted by viewing the cross-sectional echocardiograms. The thickened leaflets of the mitral orifice could easily be identified during both diastole and systole. Closure of the two leaflets was best observed early in systole before caudal movement of the anulus caused the orifice to move out of range of the ultrasonic beam. Complete closure of the leaflets was seen in patients without mitral regurgitation. Failure of closure of small areas of either the medial or lateral aspect of the valve was associated with insignificant mitral regurgitation. Failure of both sides to close or failure to close in the center of the valve indicated significant mitral regurgitation. Thus, it appears that significant mitral regurgitation in patients with rheumatic mitral valve disease can be detected by qualitative analysis of short-axis, cross-sectional echocardiograms.     

Sensitivity and specificity of two-dimensional echocardiographic signs of mitral valve prolapse

The sensitivity and specificity of previously described 2-dimensional echocardiographic signs of mitral valve prolapse (MVP) were assessed in 70 patients with MVP and in 100 normal control subjects. Specificity of individual signs was uniformly high, ranging from 88% for excessive motion of the posterior mitral ring to 100% for several signs including systolic arching in the parasternal long-axis view, excessive posterior coaptation and diastolic doming of the anterior mitral leaflet. Sensitivity of individual signs was low to moderate, ranging from 1% for whip-like motion of both mitral leaflets to 70% for excessive posterior coaptation of the mitral leaflets in the apical 4-chamber view. The highest sensitivity value (87%) was associated with the presence of systolic arching of 1 or both mitral leaflets in the parasternal long-axis view or systolic bowing of 1 or both mitral leaflets in the apical 4-chamber view or excessive posterior coaptation of the mitral leaflets or a combination. This increase in sensitivity was achieved without sacrificing specificity (97%). Thus, the individual 2-dimensional echocardiographic signs tested possess uniformly high specificity, but only low to moderate sensitivity; however, sensitivity can be markedly enhanced without sacrificing specificity by using selected combinations of echocardiographic signs.     

On the frequency of early systolic clicks in mitral valve prolapse

Phonocardiography was performed in 74 patients with mitral valve prolapse. 24 patients had early systolic clicks (less than 80 msec from S1). Four of them had associated systolic murmurs. 30 patients had mid or late systolic clicks (greater than 80 msec from S1). A systolic murmur followed the click in 13 of these patients. Both an early and mid/late systolic click were noted in three patients. 17 patients did not have systolic murmurs. Seven patients had 'silent' mitral valve prolapse. In summary, early systolic clicks are common in mitral valve prolapse. In many instances the early click is not accompanied by a murmur. Echocardiography is recommended in patients with chest pain or arrhythmia of uncertain etiology, even if characteristic signs of mitral valve prolapse are absent.     

Functional anatomy of the normal mitral apparatus: a transthoracic,two-dimensional echocardiographic study

BACKGROUND AND AIM OF THE STUDY: Normal mitral valve function relies on integrity of the leaflets, annulus, subvalvular apparatus, and the left ventricle. Echocardiography has contributed significantly to the understanding of normal and abnormal mitral valve function. Thus, plausible pathophysiologic mechanisms have been proposed for various etiologies of mitral regurgitation, based on echocardiographic measurement of a limited number of parameters. This study provides quantitative echocardiographic assessment of various components of the mitral valve-left ventricular (LV) complex. METHODS: Mitral annulus, leaflets, papillary muscles and basal LV posterior wall length were measured at end-systole and end-diastole in 10 adults (7 females, 3 males; mean age 61 +/- 15 years) with structurally and functionally normal hearts. In addition, LV size and function and left atrial and aortic root sizes were measured. RESULTS: Mitral valve competence in these normal hearts was achieved by systolic reduction in LV volume, diameter and length of 66%, 31% and 18%, respectively. The LV posterior wall (from mitral annulus to origin of the posteromedial papillary muscle) was shortened by 32%. The mitral annulus likewise showed a reduction in diameter of 6% in anteroposterior and 13% in mediolateral planes. Anterior mitral valve leaflet apposed with posterior leaflet by 23% in length in systole, whereas the papillary muscle shortened by 34%. The interpapillary muscle distance decreased by 51% in systole. CONCLUSION: These data provide echocardiographic reference values for various components of the mitral valve-LV complex in normal adults. Further studies are needed to identify the relative significance of each of these components in the pathogenesis of mitral regurgitation of various etiologies.     

Incidence of mitral valve prolapse in one hundred clinically stable newborn baby girls: an echocardiographic study.

Clinical and echocardiographic examinations were performed on 100 clinically stable, newborn baby girls. Mitral valve prolapse was noted on the echocardiograms of seven babies. Three subjects had systolic clicks, two of whom had systolic murmurs following the click. The four other babies who had echocardiographic evidence of mitral valve prolapse had no abnormal auscultatory signs. Of the 93 babies without evidence of mitral prolapse, 91 had normal echocardiograms and auscultatory features; one was noted to have a murmur consistent with a ventricular septal defect, and another had an eccentric aortic valve on the echocardiogram which was suggestive of a bicuspid aortic valve. Serial studies on our group of subjects will yield useful information regarding the natural history of mitral valve prolapse.     

Prevalence of mitral prolapse by two dimensional echocardiography in healthy young women.

In order to establish the relative prevalence of mitral valve prolapse as diagnosed by two dimensional echocardiography, we studied 100 presumably healthy young women with two dimensional echocardiography and M-mode echocardiography, history, physical examination, electrocardiography, and phonocardiography. Two dimensional echocardiograms were obtained from parasternal, apical, and subcostal acoustic windows. Mitral valve prolapse was defined as extension of leaflet tissue cephalad to the plane of the mitral annulus into the left atrium; note was also made of any valvular thickening, redundancy, or excessive annular motion. One subject had a midsystolic click and late systolic murmur with evidence of mitral prolapse on both M-mode and two dimensional echocardiography. One subject had a midsystolic click with mitral prolapse demonstrated by two dimensional but not on M-mode echocardiography. One subject had a thick mitral valve on echocardiography but no click or murmur. Four subjects had midsystolic clicks without echocardiographic abnormalities. Mild artefactual pansystolic posterior bowing of the mitral valve on the M-mode echocardiogram could be produced in 20 subjects by incorrect transducer position. We conclude that the prevalence of mitral valve prolapse by two dimensional echocardiography is relatively low in presumably healthy young women. Use of two dimensional echocardiography may avoid overdiagnosis of mitral prolapse and identify a smaller group of individuals with true anatomical abnormalities of the mitral valve.     

Differentiating clinical and echocardiographic characteristics of chordal rupture detected in patients with rheumatic mitral valve disease and floppy mitral valve: impact of the infective endocarditis on chordal rupture.

AIMS: We aimed to compare the clinical and echocardiographic correlates of chordal rupture in patients with rheumatic mitral valve disease and floppy mitral valve. METHODS AND RESULTS: The study group comprised of 224 patients who underwent transthoracic and transesophageal echocardiography because of the severe mitral regurgitation. Chordal rupture was detected in 58 (25.9%) out of the 224 patients, in 33 out of the 83 (39.7%) patients with floppy mitral valve, and in 25 out of the 141 (17.7%) patients with rheumatic mitral valve disease. Chordal rupture was more frequently associated with anterior leaflet (80%) in patients with rheumatic mitral valve disease, and posterior leaflet (72.7%) in patients with floppy mitral valve (p<0.05). Univariate correlates of chordal rupture were age, male sex, posterior mitral leaflet thickening and chordal elongation in patients with floppy mitral valve (p<0.05), and chordal shortening (p<0.0001) and infective endocarditis involving mitral anterior leaflet (p<0.05) in rheumatic group. Independent predictors of chordal rupture were age (>50 years), posterior mitral leaflet thickness (> or =0.45cm), and male sex (p<0.05) in patients with floppy mitral valve while infective endocarditis involving mitral anterior leaflet (p<0.05) in patients with rheumatic mitral valve disease. Patients with chordal rupture due to floppy mitral valve had an older age (p<0.0001), a male dominance, longer mitral leaflets and chordae, and a larger mitral annulus circumference (p<0.05) as compared to those with rheumatic chordal rupture. Despite the comparable severity of mitral regurgitation and left atrial diameters between the two groups of chordal rupture (p>0.05), functional class and pulmonary artery systolic pressure were higher, and atrial fibrillation, acute deterioration, infective endocarditis, mitral leaflet rupture and need for mitral valve surgery in the 3 months were more frequent in rheumatic chordal rupture subgroup (p<0.05). CONCLUSION: Chordal rupture seems to be more frequently associated with anterior mitral leaflet in rheumatic mitral valve disease, whereas it was the posterior leaflet in floppy mitral valve. Chordal rupture was related to male sex, older age, posterior leaflet thickening, and chordal elongation in patients with floppy mitral valve. However, infective endocarditis, acute deterioration, and need for early mitral surgery were more frequent in patients with rheumatic chordal rupture.     

Percutaneous mitral commissurotomy: immediate and short-term results]

31 symptomatic patients with mitral stenosis were selected for percutaneous transvenous mitral commissurotomy using Inoue catheter. The patients were selected using the echocardiographic score for: leaflets mobility, leaflets thickening, subvalvular thickening, degree of calcifications. All patients had a score less than or equal to 8 and represented 17.5% of the patients studied in our echocardiographic laboratory for mitral stenosis. We were able to perform the commissurotomy in 30 of them. Mean left atrial pressure decreased from 26 +/- 5.2 mmHg to 14.6 +/- 6 mmHg (p less than 0.001). The mean mitral diastolic pressure gradient decreased from 8.9 +/- 3.1 mmHg to 3.9 +/- 1.3 mmHg (p less than 0.001). The mitral valve area, using the echocardiographic Pressure Half Time (PHT), increased from 0.94 +/- 0.17 cmq to 1.96 +/- 0.33 cmq (p less than 0.001). Mitral regurgitation, angiographically evaluated in 29 patients, increased in 11 (38%), being of degree + + + in 3 patients. There were 2 heart tamponades and 5 cases (16.6%) of left-to-right shunt with Qp / Qs less than 2. After 3 months, the follow-up showed improvement of one or more functional classes in 96.6% of all patients. The mitral valve area, determined after 6 months in 24 patients by PHT, was stable (1.98 +/- 0.31 vs 1.93 +/- 0.25) (p = 0.5); we did not find mitral stenosis recurrence in any instance. In the first 10 patients, after 1 year, the results are stable (1.85 +/- 0.28 cmq vs 1.93 +/- 0.21 cmq) (p = 0.5) without mitral stenosis recurrence. These data suggest that in selected tight mitral stenosis the percutaneous transvenous commissurotomy may be alternative to the open surgical solution. Using an Inoue catheter, the percutaneous transvenous mitral commissurotomy is easier and the complications are few. The major procedural hazards derive from the transseptal technique.     

Sensitivity and specificity of M mode echocardiographic signs of mitral valve prolapse

To assess the sensitivity and specificity of previously described M mode echocardiographfc signs of mitral valve prolapse, 100 subjects with a mobile mid systolic click and 100 matched normal control subjects were prospectively studied. Late systolic posterior motion and holosystolic hammocking of the mitral leaflets were common, highly specific signs of mitral valve prolapse. When these signs were combined as a single criterion, sensitivity was 85 percent and specificity was 99 percent. Other signs, including systolic echoes in the mid left atrium, systolic anterior motion, early diastolic anterior motion of the posterior mitral leaflet and shaggy or heavy cascading linear diastolic echoes posterior to the mitral valve, were highly specific but uncommon. They occurred only in combination with late systolic posterior motion or holosystolic hammocking. The remaining signs tested did not differentiate subjects with mitral valve prolapse from normal persons.     

Motion of mitral apparatus in hypertrophic cardiomyopathy with obstruction.

Motion of the mitral apparatus in hypertrophic cardiomyopathy with obstruction was investigated by conventional single dimensional and multidimensional echocardiography. In systole, anterosuperior displacement of the posterior papillary muscle, failure of mitral valve closure, and anterior motion of both mitral leaflets were shown. The anterior leaflet was seen to impinge on the posterior papillary muscle but not on the interventricular septum in systole. The abnormality of the single dimensional mitral echogram, previously ascribed to systolic anterior motion of the mitral anterior leaflet, was found to be a complex of echoes from the chordae tendineae, the papillary muscle, and, furthest from the septum, the mitral anterior leaflet. It is concluded that systolic anterior motion of the mitral anterior leaflet is of smaller amplitude than others have suggested, and that obstruction to left ventricular outflow in hypertrophic cardiomyopathy is produced by systolic contact between the mitral anterior cusp and the posterior papillary muscle. The theory is put forward that displacement of the posterior papillary muscle above and in front of the mitral leaflets produces chordal slackening, and that it is displacement of the chordae tendineae by the blood flowing to the aortic root during left ventricular ejection, which is responsible for systolic anterior motion of the mitral leaflets.