Anomalous insertion of papillary muscle directly into anterior mitral leaflet in hypertrophic cardiomyopathy. Significance in producing left ventricular outflow obstruction

BACKGROUND. Obstruction to left ventricular outflow in hypertrophic cardiomyopathy (HCM) is usually due to systolic anterior motion of the mitral valve. Occurrence of structural mitral valve abnormalities in HCM and their significance in producing outflow obstruction (even in the absence of typical systolic anterior motion) has not been fully appreciated. METHODS AND RESULTS. Analysis of 78 mitral valves excised from patients with obstructive HCM showed that 10 (13%) had anomalous insertion of one or both left ventricular papillary muscles directly into the anterior mitral leaflet. This malformation was identified by echocardiography, which demonstrated direct continuity between the hypertrophied papillary muscle and mitral leaflet, resulting in a long rigid area of midcavity narrowing that appeared to be solely or largely responsible for outflow obstruction. Basal subaortic pressure gradients were large (70-150 mm Hg). Mitral valve replacement reduced the outflow gradient substantially to 0-15 mm Hg in four patients with postoperative cardiac catheterization. However, two other patients who underwent septal myotomy/myectomy had persistent symptoms and incomplete relief of obstruction (gradients 60 and 70 mm Hg) because of continued midcavity apposition of papillary muscle and ventricular septum. CONCLUSIONS. Anomalous papillary muscle insertion into anterior mitral leaflet represents a mechanism of obstruction to left ventricular outflow in patients with HCM and differs considerably from typical dynamic obstruction caused by mitral valve systolic anterior motion that occurs in many other patients with HCM. Recognition of this malformation emphasizes the diverse morphological expression of HCM and also has important clinical implications for patients requiring operation because the gradient is likely to persist even after adequate myotomy/myectomy; consequently, mitral valve replacement would appear to be the operation of choice in most such patients.     

The significance of systolic anterior motion (SAM) on the mitral valve echo pattern in hypertrophic cardiomyopathy

The systolic anterior motion (SAM) of valve structures in the mitral echogram in hypertrophic cardiomyopathy (HCM) has previously been considered to be anterior motion and re-opening of mitral valve leaflets, causing left ventricular outflow tract (LVOT) obstruction and mitral regurgitation. Fifteen patients with HCM underwent cardiac catheterisation and were also examined by M-scan and mechanical real-time B-scan techniques. In all patients SAM was seen during M-scan echocardiography. The mitral valve leaflets were visualised during the entire cardiac cycle during real-time B-scanning without showing any re-opening in systole. Thickened papillary muscles have been observed in 12 patients and prominent chordae tendineae moving in the opposite direction to the anterior mitral valve leaflet in 10 patients. Four patients with SAM did not show mitral regurgitation during left ventricular angiography. In two patients without fixed haemodynamic obstruction, a complete SAM touching the interventricular septum was observed with prolonged apposition in one case. These findings suggest that SAM is due to the motion of chordae tendineae and/or papillary muscles traversing the single dimensional ultrasonic beam in systole, thus producing single linear or multiple spotty echoes within SAM. The mechanism of the upward motion of the subvalvular mitral valve apparatus in systole appears to be due to forceful contraction of the apical left ventricular posterior wall. The observation of SAM in patients without HCM also indicates that its presence during single dimensional echocardiography is neither diagnostic nor specific for HCM, LVOT obstruction or mitral regurgitation, and contradicts the assumption that the anterior mitral valve leaflet plays a significant role in the mechanism of LVOT obstruction. The salient feature of all conditions associated with abnormal mitral subvalvular motion is hyperkinetic contraction of the apical left ventricular posterior wall. Hyperkinetic left ventricular ejection appears to be the main factor in the complex development of an LVOT gradient in hypertrophic cardiomyopathy.     

Doppler color flow mapping studies of jet formation and spatial orientation in obstructive hypertrophic cardiomyopathy

To help clarify the mechanism of outflow tract obstruction and systolic anterior motion of the anterior leaflet of the mitral valve and their relation to the geometry of the left ventricle, we studied left ventricular outflow tract flow in 20 patients with hypertrophic cardiomyopathy (HCM) using two-dimensional Doppler flow mapping. We compared our results with outflow tract flow in 10 patients with isolated valvular aortic stenosis, (AS) and with those in 10 healthy volunteers. In HCM, a 94- to 145-degree angle (mean 111.4 +/- 11.9 degrees) developed between the direction of left ventricular outflow tract flow acceleration and aortic valve outflow, resulting in posterolaterally directed left ventricular outflow jets. The angle of the outflow jet and the peak velocity of the jet measured with continuous wave Doppler (as an indicator of the severity of obstruction) correlated well (r = -0.81, SEE = 7.8 degrees). Jet narrowing during ejection measured just proximal to the point of systolic anterior motion was 42 +/- 11% in HCM and was weakly correlated with peak jet velocity (r = 0.61, SEE = 8.9 degrees). Aliasing of left ventricular outflow occurred proximal to systolic anterior motion of the mitral valve, and color M-mode demonstrated temporal and spatial flow acceleration proximal to systolic anterior motion, providing evidence for obstruction at that site. In AS, left ventricular outflow tract jets were more parallel to the axis of aortic outflow (129 to 153 degree, 138.4 +/- 8.1 degrees). Jet narrowing was only 8 +/- 5% compared to HCM (both p less than 0.05), and flow acceleration occurred proximal to the stenotic valve.(ABSTRACT TRUNCATED AT 250 WORDS)     

Underappreciated occurrence of discrete subaortic membranes producing left ventricular outflow obstruction in hypertrophic cardiomyopathy

Subaortic obstruction due to systolic anterior motion (SAM) of the mitral valve with ventricular septal contact is a major cause of progressive heart failure symptoms in patients with hypertrophic cardiomyopathy (HCM). However, we have recently observed a unique, but not uncommon subgroup of HCM patients with outflow tract obstruction due only to discrete subaortic membrane or who have a membrane in addition to SAM‐septal contact. HCM patients with subaortic membranes may be at increased risk for developing progressive heart failure symptoms. Identification requires a high index of suspicion and raises important management considerations, including need for surgical myectomy for definitive relief of obstruction with associated excellent outcomes, as the alternative invasive treatment option with percutaneous alcohol septal ablation would be ineffective.     

肥厚梗阻性心肌病与二尖瓣病变及二尖瓣反流

目的:探讨左心室流出道梗阻对二尖瓣叶及二尖瓣反流的影响。方法:采用数字化超声心动图技术分析左心室流出道梗阻患者二尖瓣前叶形态结构及二尖瓣反流的特点。结果:68例左心室流出道梗阻患者,其中2例二尖瓣前叶赘生物形成合并穿孔,66例二尖瓣前叶近瓣缘部分轻度增厚。全部患者均有明显二尖瓣前叶收缩期前向运动(SAM)及二尖瓣偏心反流。结论:左心室流出道梗阻可引起二尖瓣前叶病变。左心室流出道梗阻患者二尖瓣前叶SAM可导致二尖瓣反流。     

B-scan ultrasonography in idiopathic hypertrophic subaortic stenosis. Study of left ventricular outflow tract and mechanism of obstruction.

Studies were made with standard time motion and B-scan echocardiography on 48 patients including 5 with idiopathic hypertrophic subaortic stenosis (hypertrophic obstructive cardiomyopathy), undergoing diagnostic cardiac catheterization. The dimensions of the left ventricular outflow (O) and inflow (I) tracts were measured on the B-scan images. The outflow tract was significantly narrowed in idiopathic hypertrophic subaortic stenosis at both end-systole (1-1+/-0-1 cm) and end-diastole (1-3+/-0-1 cm) when compared with the average width in other patients (2-6+/-0-1 and 3-0+/-0-1 cm, at end-systole and end-diastole, respectively) (P less than 0-001) or normal subjects (2-4+/-0-3 and 2-9+/-0-2 cm) (P less than 0-01). Furthermore, the O/I ratio differed significantly in idiopathic hypertrophic subaortic stenosis (0-5+/-0-1 at end-systole and 0-6+/-0-1 at end-diastole) from that in all other groups (1-4+/-0-1 at both end-systole and end-diastole) (P less than 0-005). There was no appreciable change in the width of the outflow tract from mid- to end-systole in the two patients in whom this was examined. The data support the contention that the anterior leaflet of the mitral valve assumes an abnormally anterior position in idiopathic hypertrophic subaortic stenosis. Though the systolic anterior movement of the tip of the anterior leaflet of the mitral valve shown by M-mode echocardiography could not readily be confirmed with B-scans, we believe that the narrowed outflow tract found in the present investigation contributes to the obstruction that occurs in this disease. We suggest that this outflow tract narrowing is probably caused by hypertrophy of the ventricular septum which in itself contributes to the narrowing, but which also displaces the papillary muscles and thus produces abnormal traction on the mitral valve and striking anterior displacement of the valve apparatus.     

Fixed subaortic stenosis: anatomical spectrum and nature of progression.

Retrospective echocardiographic review identified 58 consecutive infants and children with fixed subaortic stenosis. Mean (SD) age at diagnosis was 4.8 (3.6) years (range two days to 14.7 years), and diagnosis occurred in infancy in eight. Associated cardiac abnormalities were present in 41 (71%) whereas fixed subaortic stenosis was an isolated lesion in 17 (29%). Four types of fixed subaortic stenosis were identified: short segment (47 (81%)), long segment (7 (12%)), posterior displacement of the infundibular septum with additional discrete narrowing of the left ventricular outflow tract (3 (5%)), and redundant tissue arising from the membranous septum (1 (2%)). Echocardiographic studies had been performed before the diagnosis of fixed subaortic stenosis in nine patients, all with associated abnormalities. These were performed in infancy in each and showed a "normal" left ventricular outflow tract in six and posterior deviation of the infundibular septum in three. In 16 patients serial echocardiographic studies had been performed after the diagnosis of fixed subaortic stenosis but before surgery of the left ventricular outflow tract. Rapid evolution of short segment to long segment narrowing was seen in one patient, and tethering of the aortic valve or mitral valve developed in a further four patients. Aortic valve or mitral valve involvement was not seen before the age of three years but was common thereafter (10/40 patients, 25%). Fixed subaortic stenosis may be an "acquired" lesion with the potential for changes in form as well as progression in severity of left ventricular outflow tract obstruction.     

Mitral valve remodeling in the development of obstructive hypertrophic cardiomyopathy

Approximately 2/3 of patients with hypertrophic cardiomyopathy (HCM) have significant left ventricular outflow tract obstruction (LVOTO), which is caused by the interaction mitral valve apparatus and the hypertrophied septum. The contribution of mitral valve remodeling to the development of obstruction over time has never been described. We analyzed retrospectively 40 patients with HCM and no baseline obstruction followed up for a median of 2179 days. At follow up, 13 patients developed significant LVOTO. Patients who developed LVOTO had longer posterior leaflets and longer anterior leaflet residual length.     

Fixed subaortic stenosis: anatomical spectrum and nature of progression

Retrospective echocardiographic review identified 58 consecutive infants and children with fixed subaortic stenosis. Mean (SD) age at diagnosis was 4.8 (3.6) years (range two days to 14.7 years), and diagnosis occurred in infancy in eight. Associated cardiac abnormalities were present in 41 (71%) whereas fixed subaortic stenosis was an isolated lesion in 17 (29%). Four types of fixed subaortic stenosis were identified: short segment (47 (81%)), long segment (7 (12%)), posterior displacement of the infundibular septum with additional discrete narrowing of the left ventricular outflow tract (3 (5%)), and redundant tissue arising from the membranous septum (1 (2%)). Echocardiographic studies had been performed before the diagnosis of fixed subaortic stenosis in nine patients, all with associated abnormalities. These were performed in infancy in each and showed a "normal" left ventricular outflow tract in six and posterior deviation of the infundibular septum in three. In 16 patients serial echocardiographic studies had been performed after the diagnosis of fixed subaortic stenosis but before surgery of the left ventricular outflow tract. Rapid evolution of short segment to long segment narrowing was seen in one patient, and tethering of the aortic valve or mitral valve developed in a further four patients. Aortic valve or mitral valve involvement was not seen before the age of three years but was common thereafter (10/40 patients, 25%). Fixed subaortic stenosis may be an "acquired" lesion with the potential for changes in form as well as progression in severity of left ventricular outflow tract obstruction.     

Frequency and mechanism of persistent systolic anterior motion and mitral regurgitation after septal ablation in obstructive hypertrophic cardiomyopathy

Relief of obstruction using ventricular septal ablation (VSA) may not eliminate systolic anterior motion (SAM) of the mitral valve and mitral regurgitation (MR) in patients with obstructive hypertrophic cardiomyopathy. The hypothesis was that persistent SAM after VSA was secondary to anterior papillary muscle displacement and malcoaptation of mitral valve leaflets and that these findings could predict persistence of SAM. Echocardiograms were examined from 37 patients with obstructive hypertrophic cardiomyopathy before and 12+/-3 months after VSA. Anterior leaflet malposition (anterior-to-posterior leaflet coaptation position ratio), papillary muscle malposition (septal-to-lateral/left ventricular internal diameter ratio), and anterior position of coaptation relative to the septum (coaptation-to-septal distance) were assessed. MR proximal jet width was also measured. Of 37 patients, 30 underwent successful VSA (left ventricular outflow tract gradient reduction>50%); 22 of 30 and 7 of 7 with <50% reduction (total 29 of 37; 78%) showed persistent SAM at 12+/-3 months. These patients had more anterior malposition of the mitral valve and less MR reduction than those without SAM: anterior-to-posterior leaflet coaptation position ratio 0.42+/-0.06 versus 0.56+/-0.09, septal-to-lateral/left ventricular internal diameter ratio 0.39+/-0.12 versus 0.55+/-0.12, coaptation-to-septal distance 1.8+/-0.42 versus 2.8+/-0.30 cm, and MR reduction by 29+/-22% versus 71+/-12% (p<0.0001). Gradients, both at rest and provokable, were higher (27+/-33 vs 4+/-5 mm Hg, p=0.0004; >45 mm Hg in 9 vs 0, p=0.03, respectively) in patients with persistent SAM. Anterior malposition was present before VSA, with anterior-to-posterior leaflet coaptation position ratio<0.5 predicting SAM after VSA (p<0.0001). In conclusion, SAM and MR were often not eliminated using VSA. Mitral valve malposition was a strong predictor of SAM and MR reduction after VSA and may need to be considered in optimizing results of this procedure.     

Significance of left ventricular outflow tract cross-sectional area in hypertrophic cardiomyopathy: a two-dimensional echocardiographic assessment

The morphologic determinants of subaortic obstruction in patients with hypertrophic cardiomyopathy are not completely understood. To define the relation between left ventricular outflow tract orifice size and presence or absence of subaortic obstruction, we studied 65 patients with hypertrophic cardiomyopathy and 16 normal controls by quantitative two-dimensional echocardiography. Left ventricular outflow tract area was measured at the onset of systole in the short-axis view in the stop-frame mode. Left ventricular outflow tract area was significantly smaller in patients with hypertrophic cardiomyopathy and subaortic obstruction (2.6 +/- 0.7 cm2) than in patients without obstruction (5.9 +/- 1.6 cm2, p less than 0.001). Twenty of 21 patients with obstruction had a left ventricular outflow tract area smaller than 4.0 cm2, whereas 28 of 30 patients without obstruction had a left ventricular outflow tract area of 4.0 cm2 or greater. The outflow tract area in patients with provocable obstruction (4.6 +/- 1.6 cm2) was intermediate between the areas of patients with and without obstruction. Left ventricular outflow tract area was significantly smaller in patients with hypertrophic cardiomyopathy (4.6 +/- 2.0 cm2) than in normal subjects (10.4 +/- 1.2 cm2, p less than 0.001). We conclude that the cross-sectional outflow tract area is closely related to the presence or absence of subaortic obstruction in patients with hypertrophic cardiomyopathy. Hence, the size of the outflow tract at the level of the mitral valve appears to be of major pathophysiologic significance in producing obstruction in these patients.     

Dynamic left ventricular outflow tract obstruction and systolic anterior motion of the mitral valve in the absence of asymmetric septal hypertrophy

Systolic anterior motion of the anterior mitral valve leaflet and asymmetric septal hypertrophy are the principal components of the dynamic subaortic stenosis in hypertrophic obstructive cardiomyopathy. Mitral valve systolic anterior motion without septal hypertrophy or left ventricular outflow tract obstruction has been described, but asymmetric septal hypertrophy is supposedly a consistent feature of dynamic subaortic stenosis. We describe two patients with syncope, chest pain and the typical systolic murmur of hypertrophic subaortic stenosis whose echocardiograms showed mitral valve systolic anterior motion but not asymmetric septal hypertrophy. Normal septal thickness on echo was confirmed by intravenous indocyanine green to identify the right septal endocardium. At catheterization, left ventricular outflow tract gradients were provoked, and neither patient had interventricular septal hypertrophy on biventricular cineangiography. These findings in two cases suggest that mitral valve systolic anterior motion can be the only definable anatomic abnormality associated with symptomatic dynamic left ventricular outflow tract obstruction and that asymmetric septal hypertrophy is not a necessary component of this condition.     

Markedly abnormal mitral valve motion without simultaneous intraventricular pressure gradient due to uneven mitral-septal contact in idiopathic hypertrophic subaortic stenosis

Although echocardiographic analysis reliably diagnoses idiopathic hypertrophic subaortic stenosis by detection of systolic forward anterior mitral valve motion and estimates severity of obstruction by the timed mitral encroachment of the interventricular septum, echographic stenosis may occur without hemodynamic obstruction or pressure gradient across the left ventricular outflow tract. Demonstration and mechanism of this apparent inconsistency are described in three patients with a previously unrecognized state of Idiopathic hypertrophic subaortic stenosis characterized by marked systolic forward movement of the anterior mitral valve without a simultaneous intraventricular pressure gradient, resulting from uneven septal apposition by the anterior leaflet. Echographic obstruction indexes (40, 34 and 31) during cardiac catheterization in the three patients were predictive of respective peak gradients of 37, 25 and 20 mm Hg. The horizontal nonparallel mitralseptal contact consistent with severe systolic forward movement of the anterior mitral valve in the absence of hemodynamic stenosis is believed to be caused by markedly forward displacement of the anterior papillary muscle, so that its chordae tendineae produce greater tension on the posteromedial aspect of the anterior mitral valve. Thereby the posterior portion of the leaflet is pulled forward more than its anterior side, allowing marked systolic forward anterior mitral valve motion without a pressure gradient in idiopathic hypertrophic subaortic stenosis.     

Mitral valve replacement and limited myectomy for hypertrophic obstructive cardiomyopathy: a 25-year follow-up

Hypertrophic obstructive cardiomyopathy is a dynamic obstruction of the left ventricular outflow tract caused by septal hypertrophy and systolic anterior motion of the mitral valve. When the condition cannot be controlled by medical therapy the most frequently used surgical approach is left ventricular myotomy-myectomy. Mitral valve replacement (to correct another mechanism of obstruction) is another surgical option; however, its use for this condition is controversial. We review the long-term results of patients who underwent limited left ventricular myotomy-myectomy and mitral valve replacement at our institution. Eighteen patients who had hypertrophic obstructive cardiomyopathy and severe mitral insufficiency underwent surgery between 1978 and 1983: 7 were men and 11 were women (mean age, 41.8 +/- 10.5 years). Preoperatively, most of the patients (78.8%) were in New York Heart Association functional class III or IV. The operation consisted of a shallow myectomy of the hypertrophied septum and mitral valve replacement. One patient died in the hospital (5.5%); 3 patients died later during follow-up. The remaining 14 patients are alive and in good condition (mean follow-up, 21.9 +/- 1.7 years). Functional class improved postoperatively in all surviving patients. The mean left ventricular outflow tract gradient fell from 78.1 +/- 20.9 mmHg preoperatively to 9.4 +/- 5.2 mmHg postoperatively (P <0.001). At present, surgical treatment of hypertrophic obstructive cardiomyopathy does not include mitral valve replacement. However, our long-term results show that limited ventricular myectomy and mitral valve replacement predictably and consistently lower the left ventricular outflow tract gradient and resolve the mitral valve insufficiency.     

Aortic regurgitation in hypertrophic cardiomyopathy as detected by color Doppler echocardiography

Aortic regurgitation (AR) in patients with hypertrophic cardiomyopathy (HCM) has rarely been reported. Using color Doppler echocardiography, we assessed the incidence and the cause of AR in patients with HCM. There were 86 patients with HCM (M:F = 66: 20, 57 +/- 12 years, mean +/- SD) and 43 control subjects (M: F = 33: 10, 57 +/- 8 years). HCM was diagnosed by echocardiography; the thickness of the interventricular septum (IVS) was more than 15 mm and the ratio to the thickness of the left ventricular free wall (LVPW) was more than 1.3. The rate and degree of aortic regurgitation were observed by color Doppler echocardiography, and aortic regurgitant murmurs were recorded by phonocardiography. Echocardiographic measurements were made using standard techniques. In the M-mode echocardiograms, the aortic diameter, the thicknesses of the IVS and LVPW were measured. In the 2DE, calcification of the aortic valve and systolic anterior movement of the mitral valve (SAM) were evaluated. In the early systolic 2DE image, the distance from the point of the greatest bulging of the upper IVS to the aortic root (D1) and the distance from the point of the greatest bulging to the line which is parallel to the long axis of the aorta (D2) were measured. Results were as follows: 1. Color Doppler echocardiography revealed aortic regurgitation in 17 (21%) patients with HCM; whereas it was observed in only three (7%) of the control subjects. 2. The aortic regurgitant signals were limited to the left ventricular outflow tract both in patients with HCM and in the control subjects. 3. Aortic regurgitant murmurs were recorded in only two patients with HCM and in none of the control subjects. 4. There was no difference between the patients with and without AR as to age (59 vs 56 years), blood pressure (141/84 vs 136/80 mmHg), aortic diameter (34 vs 33 mm), aortic valve calcification (12% vs 9%) and SAM (53% vs 52%). 5. In the patients with HCM, D1 was shorter (9.9 vs 14 mm, p less than 0.001) and D2 was longer (16 vs 10 mm, p less than 0.001) in the patients with AR than in those without AR. That is, the basal septum of the patients with AR protruded more deeply into the outflow tract, and the distance to the aortic valve was significantly shorter than in those without AR.(ABSTRACT TRUNCATED AT 400 WORDS)     

Mechanism of left ventricular outlfow obstruction in patients with obstructive asymmetric septal hypertrophy (idiopathic hypertrophic subaortic stenosis).

Left ventricular outflow obstruction in patients with idiopathic hypertrophic subaortic stenosis or obstructive asymmetric septal hypertrophy is due to abnormal forward motion during systole of the anterior mitral leaflet. To determine why some patients with this disease hav left ventricular outflow obstruction whereas others do not, we studied a large number of patiens with assymetric septal hypertrophy using both one- and two-dimensional echocardiography. In 100 patients with asymmetric septal hypertrophy and 22 normal subjects, mitral valve position at the onset of systole was quantitated by measuring the distance from the ventricular septum to the mitral valve and the distance from the mitral valve to the posterior left ventricular wall. None of the normal subjects and only 3 (6 percent) of 51 patients with nonobstructive asymmetric septal hypertrophy had a septal-mitral valve distance of less than 20 mm compared with 23 (66 percent) of 35 patients with obstructive asymmetric septal hypertrophy. Moreover, the mitral valve at the onset of systole was actually positioned forward in the left ventricular activity. Two-dimensional studies in 11 patients with obstructive asymmetric septal hypertrophy revealed that contraction of the malaligned papillary muscles did not cause the abnormal forward mitral valve motion. We propose that the left ventricular outflow obstruction in patients with obstructive asymmetric septal hypertrophy occurs as a result of two factors: (1) narrowing of the left ventricular outflow tract at the onset of systole, and (2) hydrodynamic forces generated by contraction on the left ventricle.     

Left ventricular systolic and diastolic flow abnormalities determined by Doppler echocardiography in obstructive hypertrophic cardiomyopathy

To analyze the relation of systolic anterior motion (SAM) of the mitral valve, peak left ventricular (LV) outflow tract velocity, aortic flow and mitral flow, 17 patients with obstructive hypertrophic cardiomyopathy (HC) (8 men, 9 women), aged 19 to 88 years (mean 45), were studied using M-mode and 2-dimensional echocardiography and pulsed and continuous-wave Doppler echocardiography and results were compared with those from 18 age-matched normal subjects. SAM was present in all patients with HC and absent in normal subjects. Time to peak outflow velocity as a percentage of LV ejection time was 63% in patients with HC and 29% in normal subjects (p less than 0.001). In 13 patients, time from the R-wave peak to the closest approximation of the mitral valve to the ventricular septum or initial contact during SAM was determined and was 242 +/- 66 ms and time from the R-wave peak to the peak LV outflow tract velocity was 242 +/- 73 ms (r = 0.90). In 11 patients time from the R-wave peak to cessation of flow in the ascending aorta was measured and was 286 +/- 80 ms; time from the R-wave peak to the peak LV outflow tract velocity was 246 +/- 75 ms. The ratio of early to late diastolic filling velocities of the left ventricle was 1.47 +/- 0.40 in the normal subjects and 1.26 +/- 0.84 in patients with HC (difference not significant). The early to late ratio of the 12 patients without mitral regurgitation was 0.99 +/- 0.52 (p less than 0.01 vs normal subjects).(ABSTRACT TRUNCATED AT 250 WORDS)     

Systolic anterior motion of the mitral valve in the absence of asymmetric septal hypertrophy.

Asymmetric septal hypertrophy (ASH) is considered the unifying link in the spectrum of hypertrophic cardiomyopathies. ASH and mitral valve systolic anterior motion (SAM) are the two most important echocardiographic criteria for the diagnosis of idiopathic hypertrophic subaortic stenosis (IHSS). Ten patients found have SAM without ASH were studied. Septal thickness, thickening, and excursion were normal. Seven patients had left ventricular ejection times (LVET) measured before and after amyl nitrite inhalation. In six of them, corrected LVET increased by more than 40 msec. Four patients underwent diagnostic cardiac catheterization. Resting or provocable left ventricular outflow tract (LVOT) gradients were demonstrable in all four patients. The echocardiographic features in patients with SAM alone, ASH and SAM, and ASH alone were compared. compared. LVOT measurements in patients with SAM alone (2.2 +/- .4 cm) and ASH and SAM (2.1 +/- .5 cm) were similar and narrower than in patients with ASH alone (2.8 +/- .5 cm, P less than 0.001). Ejection fractions in patients with SAM alone (79 +/- 10%) were greater than in patients with ASH and SAM (66 +/- 16%, P less than 0.02) or ASH alone (60 +/- 15%, P less than 0.001). Thus, dynamic left ventricular outflow obstruction can exist in the absence of echocardiographic ASH. LVOT width and abnormal LV ejection dynamics may contribute to the LVOT obstruction with or without the presence of ASH.     

Understanding Left Ventricular Outflow Obstruction: Anatomoechocardiographic Correlation

Objective. Echocardiography is a valuable noninvasive technique for identifying the site and type of obstruction in the left ventricular outflow tract. Knowledge of the morphological details of each type of obstruction is the basis for correct interpretation of the diagnostic images and clinical decisions. Methods. This study was undertaken to provide improved understanding of the anatomy of left ventricular outflow obstruction with corresponding side‐by‐side echocardiographic images. Specimens were part of the collection of the Department of Embryology of the Instituto Nacional de Cardiología “Ignacio Chávez,” Mexico City, Mexico. Twenty‐eight patients were studied by echocardiography, and 22 specimens with different types of left ventricular outflow tract obstruction were analyzed. Results. Echocardiographic characteristics: Eighteen (64.3%) patients were women and 10 (35.7%) men. Three had fibrous rings, 19 with obstructive asymmetric septal hypertrophic cardiomyopathy, 1 with posterior displacement of the infundibular septum, 2 with accessory mitral valve tissue, 2 with anomalous insertion of mitral valve chordae tendineae, and 1 with malposition of the mitral valve and papillary muscles. Anatomic characteristics: Twelve had fibrous ring, 2 asymmetric septal hypertrophic cardiomyopathy, 2 posterior displacement of the infundibular septum, 1 ectopic mitral tissue, 1 anomalous insertion of mitral valve chordae tendineae in the ventricular septum, 3 malposition of the mitral valve and papillary muscles, and 1 subaortic infundibulum. Conclusion. The anatomoechocardiographic correlation clearly demonstrates the mechanism of subaortic obstruction. The comparison with corresponding echocardiographic images of different subaortic obstruction types is potentially quite valuable in enhancing the echocardiographer’s understanding especially of complex subaortic obstruction.     

Systolic anterior motion of the mitral valve after mitral valve repair: a method of prevention

Factors predisposing patients to systolic anterior motion of the mitral valve (SAM) with left ventricular outflow tract (LVOT) obstruction after mitral valve repair are the presence of a myxomatous mitral valve with redundant leaflets, a nondilated hyperdynamic left ventricle, and a short distance between the mitral valve coaptation point and the ventricular septum after repair. From December 1999 through March 2000, we used our surgical method in 6 patients with severely myxomatous regurgitant mitral valves who were at risk of developing SAM. Leaflets were markedly redundant in all 6. Left ventricular function was hyperdynamic in 4 patients and normal in 2. Triangular or quadrangular resection of the midportion of the posterior leaflet and posterior band annuloplasty were performed. To prevent SAM and LVOT obstruction, extra, posteriorly directed, mid-posterior-leaflet secondary chordae tendineae, which would otherwise have been resected, were transferred to the underside of the middle of the mid-anterior leaflet with a small piece of associated valve as an anchoring pledget. This kept the redundant anterior leaflet edge, which extended below the coaptation point, away from the LVOT No post-repair SAM or LVOT obstruction was observed on intraoperative or discharge echocardiography. All patients had no or trivial residual mitral regurgitation. We conclude that extra chordae tendineae, when available, can be used in mitral valve repair to tether the redundant anterior leaflet and thus prevent it from flipping into the LVOT. This will theoretically prevent SAM and LVOT obstruction in patients with risk factors for SAM.