Spectrum of structural abnormalities in floppy mitral valve echocardiographic evaluation

Secondary leaflet tethering in patients with severe degenerative mitral regurgitation and its association with the severity of mitral regurgitation

BACKGROUND

The purpose of the study was to determine the association between vena contracta area (VCA) and secondary leaflet tethering among mitral valve prolapse (MVP) patients, and thus to further identify and characterize an MVP with pathological leaflet tethering (MVPt+) phenotype.

METHODS

We prospectively evaluated 94 consecutive MVP patients with significant mitral regurgitation (MR) and 21 healthy controls. MVPt+ group was defined as tenting volume index (TVi) > .7 mL/m2 . The three-dimensional (3D) geometry of mitral valve apparatus and VCA was measured with dedicated quantification software.

RESULTS

Of the 94 patients with MVP and significant MR, 31 patients showed a TVi > .7 mL/m2 and entered the MVP with leaflet tethering (MVPt+) group. In stepwise multivariate analysis, only prolapse volume index and TVi were independently associated with 3D VCA. 3D VCA, annular area index, and plasma levels of NT-proBNP were independently correlated with the severity of leaflet tethering. ROC curve revealed that a 3D VCA ≥ .55 cm2 is the optimal cutoff point to predict MVPt+ phenotype.

CONCLUSIONS

Secondary leaflet tethering is a significant mechanism behind severe degenerative MR, resulting in an MVPt+ phenotype featuring more advanced morphological and hemodynamical characteristics.

Synoptic reporting of echocardiography in carcinoid heart disease (ENETS Carcinoid Heart Disease Task Force)

BACKGROUND

This European Neuroendocrine Tumor Society (ENETS) Expert Consensus document aims to provide practical guidance and standardization for echocardiography in the screening and follow-up of carcinoid heart disease (CHD) in patients with a neuroendocrine tumour (NET) and carcinoid syndrome.

METHODS

NET experts within the ENETS Carcinoid Heart Disease Task Force reviewed both general reporting guidelines and specialized scoring systems for transthoracic echocardiography (TTE) in CHD. Based on this review, a dedicated template report was designed by the multidisciplinary working group of cardiologists, oncologists, endocrinologists, gastroenterologists, surgeons and radiologists.

RESULTS

We propose a Synoptic Reporting of Echocardiography in Carcinoid Heart Disease which represents an agreed peer reviewed proforma to capture information at the time of referral and enable a detailed outcome of CHD assessment. This includes a systematic and detailed list of structures to evaluate data to capture at the time of reporting of TTE.

CONCLUSIONS

Adherence to these reporting guidelines aims to promote homogeneous and detailed evaluation of CHD to secure accurate assessment and allow comparison of studies performed intra- and inter-individually. These guidelines could also facilitate CHD assessment as part of prospective clinical trials to enable standardization of the findings seen in response to therapy.

Mitral Leaflet Changes Following Myocardial Infarction: Clinical Evidence for Maladaptive Valvular Remodeling

BACKGROUND

Ischemic mitral regurgitation (MR) is classically ascribed to functional restriction of normal leaflets, but recent studies have suggested post-myocardial infarction (MI) mitral valve (MV) leaflet fibrosis and thickening, challenging valve normality. Progression of leaflet thickness post-MI has not been studied. We hypothesized that excessive MV remodeling post-MI contributes to MR. Our objectives are to characterize MV changes after MI and relate them to MR.

METHODS AND RESULTS

Three groups of 40 patients with serial echocardiograms over a mean of 23.4 months were identified from an echocardiography database: patients first studied early (6±12 days) and late (12±7 years) after an inferior MI and normal controls. MV thickness was correlated with MR. We studied the mechanisms for MV changes in a sheep model (6 apical MI versus 6 controls) followed for 8 weeks, with MV cellular and histopathologic analyses. Early post-MI, leaflet thickness was found to be similar to controls (2.6±0.5 vs 2.5±0.4 mm; P=0.23) but significantly increased over time (2.5±0.4 to 2.9±0.4 mm; P<0.01). In this group, patients tolerating maximal doses of renin-angiotensin blocking agents had less thickening (25% of patients; P<0.01). The late-MI group had increased thickness (3.2±0.5 vs 2.5±0.4 mm; P<0.01) without progression. At follow-up, 48% of post-MI patients had more than mild MR. Increased thickness was independently associated with MR. Experimentally, 8 weeks post-MI, MVs were 2-fold thicker than controls, with increased collagen, profibrotic transforming growth factor-β, and endothelial-to-mesenchymal transformation, confirmed by flow cytometry.

CONCLUSIONS

MV thickness increases post-MI and correlates with MR, suggesting an organic component to ischemic MR. MV fibrotic remodeling can indicate directions for future therapy.

Current Discoveries and Interventions for Barlow's Disease

Mitral valve prolapse is a common valve pathology. One particular type of mitral valve prolapse that can be difficult to treat is Barlow's disease. This review serves to give insight on the current discoveries and therapeutic interventions of Barlow's disease.

Matrix Metalloproteinase Polymorphisms in Patients with Floppy Mitral Valve/Mitral Valve Prolapse (FMV/MVP) and FMV/MVP Syndrome

BACKGROUND

It has been suggested that collagen abnormalities of the mitral valve are present in patients with floppy mitral valve (FMV)/mitral valve prolapse (MVP). Genetic factors determining collagen synthesis and degradation have not been well defined in these patients. This study was undertaken to determine whether selective polymorphisms of matrix metalloproteinase-2 (MMP2) or transforming growth factor-β (TGFβ), with known or putative effects on collagen turnover, are more frequent in FMV/MVP.

METHODS

Single nucleotide polymorphisms (SNPs) in select genes related to collagen turnover, including MMP2 rs2285053, MMP2 rs243865, TGFβ1 rs1800469, and TGFβ2 rs900, were determined in 98 patients with FMV/MVP who had severe mitral regurgitation and compared to 99 controls.

RESULTS

MMP2 rs243865 was the only SNP significantly associated with FMV/MVP as compared to the control (odds ratio 2.07, 95% CI 1.23-3.50, p = 0.006). MMP2 rs228503 was the only SNP significantly associated with the FMV/MVP syndrome as compared to patients with FMV/MVP without the syndrome (odds ratio 2.41, 95% CI 1.08-5.40, p = 0.032).

CONCLUSION

The frequency of certain MMP2 polymorphisms is higher in patients with the FMV/MVP syndrome and patients with FMV/MVP without the syndrome. The data suggest that a genetic predisposition that alters collagen turnover may play a role in the pathogenesis and development of FMV/MVP.

Floppy mitral valve/mitral valve prolapse syndrome: Beta-adrenergic receptor polymorphism may contribute to the pathogenesis of symptoms

BACKGROUND

Certain patients with floppy mitral valve (FMV)/mitral valve prolapse (MVP) may have symptoms that cannot be explained on the severity of mitral valvular regurgitation (MVR) alone; hypersensitivity to adrenergic stimulation has been suggested in this group defined as the FMV/MVP syndrome.

METHODS

Ninety-eight patients (75 men, 23 women) with mitral valve surgery for FMV/MVP were studied. Of those 41 (42%) had symptoms consistent with FMV/MVP syndrome [29 men (39%), 12 women (52%)]; median age of symptom onset was 30 years (range 10-63 years) and median duration of symptoms prior to valve surgery was 16 years (range 3-50 years). Ninety-nine individuals (70 men, 29 women) without clinical evidence of any disease were used as controls. Genotyping of β1 and β2 adrenergic receptors was performed.

RESULTS

β-Adrenergic receptor genotypes (β1 and β2) were similar between control and overall FMV/MVP patients. Subgroup analysis of patients, however, demonstrated that the genotype C/C at position 1165 resulting in 389 Arg/Arg of the β1 receptor was more frequent in women compared to those without FMV/MVP syndrome and to normal control women (p<0.025). This polymorphism may be related to hypersensitivity to adrenergic stimulation as reported previously in these patients.

CONCLUSION

This study shows a large proportion of patients with FMV/MVP, predominantly women, had symptoms consistent with the FMV/MVP syndrome for many years prior to the development of significant MVR, and thus symptoms cannot be attributed to the severity of MVR alone. Further, women with FMV/MVP syndrome, symptoms at least partially may be related to β1-adrenergic receptor polymorphism, which has been shown previously to be associated with a hyperresponse to adrenergic stimulation.

Increased frequency of mitral valve prolapse in patients with deviated nasal septum

Any abnormality of collagen may affect the tissues with higher collagen content, e.g., joints, heart valves, and great arteries. Mitral valve prolapse (MVP) is a characteristic of generalized collagen abnormality. Nasal septum (NS) is constituted by osseous and cartilaginous septums that are highly rich in collagen. We evaluated the co-existence of deviation of NS (DNS) in patients with MVP. We retrospectively evaluated the recordings of echocardiographic and nasal examinations of subjects with MVP and DNS. We analyzed the features of MVP and anatomical classification of DNS among subjects. Totally, 74 patients with DNS and 38 subjects with normal nasal passage were enrolled to the study. Presence of MVP was significantly higher in patients with DNS compared to normal subjects (63 vs 26%, p < 0.001). Prolapse of anterior, posterior and both leaflets was higher in patients with DNS. Thickness of anterior mitral leaflet was significantly increased in patients with DNS (3.57 ± 0.68 vs 4.59 ± 1.1 mm, p < 0.001) compared to normal subjects. Type I, II, and III, IV DNS were higher in frequency in patients with MVP while type V and VI were higher in normal subjects. DNS is highly co-existent with MVP and increased thickness of mitral anterior leaflet. Generalized abnormality of collagen which is the main component of mitral valves and nasal septum may be accounted for co-existence of MVP and DNS. Also co-existence of them may exaggerate the symptoms of patients with MVP due to limited airflow through the nasal passage.

Mitral valve enlargement in chronic aortic regurgitation as a compensatory mechanism to prevent functional mitral regurgitation in the dilated left ventricle

OBJECTIVES

The aim of this study was to test the hypothesis that mitral valve (MV) enlargement occurring in chronic aortic regurgitation (AR) prevents functional mitral regurgitation (FMR).

BACKGROUND

Chronic AR causes left ventricular (LV) dilation, creating the potential for FMR. However, FMR is typically absent during compensated AR despite substantial LV enlargement. Increased mitral leaflet area has been identified in AR, but it is unknown whether increased MV size can represent a compensatory mechanism capable of preventing FMR.

METHODS

Database review of 816 patients with at least moderate AR evaluated the prevalence of FMR. A total of 90 patients were enrolled prospectively for 3-dimensional echocardiography (30 AR, 30 FMR, and 30 controls) to assess MV geometry including total leaflet area.

RESULTS

FMR was present in 5.6% of AR patients by database review. Prospectively, only 1 AR patient had more than mild FMR despite increased LV end-diastolic volume (82 ± 22, 86 ± 23, and 51 ± 12 cm(3)/m(2), respectively, for AR, FMR vs. control patients; p < 0.01) and similar sphericity index, annular area, and tethering distances compared with FMR. Total MV area was largest in AR (31.3% greater than normal), increasing significantly more than in FMR. The ratio of valve size to closure area was maintained in AR, whereas decreases in this ratio and LV ejection fraction independently predicted FMR.

CONCLUSIONS

FMR prevalence is low in chronic AR. MV leaflet area is significantly increased compared with control and FMR patients, preserving a normal relationship to the area needed for closure in the dilated LV. Understanding the mechanisms underlying this adaptation could lead to new therapeutic interventions to prevent FMR.

Quantitative analysis of mitral valve morphology in mitral valve prolapse with real-time 3-dimensional echocardiography: importance of annular saddle shape in the pathogenesis of mitral regurgitation

BACKGROUND

Few data exist on the relation of the 3-dimensional morphology of mitral valve and degree of mitral regurgitation (MR) in mitral valve prolapse.

METHODS AND RESULTS

Real-time 3-dimensional transesophageal echocardiography of the mitral valve was acquired in 112 subjects, including 36 patients with mitral valve prolapse and significant MR (≥3+; MR+ group), 32 patients with mitral valve prolapse but no or mild MR (≤2+; MR- group), 12 patients with significant MR resulting from nonprolapse pathologies (nonprolapse group), and 32 control subjects. The 3-dimensional geometry of mitral valve apparatus was measured with dedicated quantification software. Compared with the normal and MR- groups, the MR+ group had more dilated mitral annulus (P<0.0001), a reduced annular height to commissural width ratio (AHCWR) (P<0.0001) indicating flattening of annular saddle shape, redundant leaflet surfaces (P<0.0001), greater leaflet billow volume (P<0.0001) and billow height (P<0.0001), longer lengths from papillary muscles to coaptation (P<0.0001), and more frequent chordal rupture (P<0.0001). Prevalence of chordal rupture increased progressively with annulus flattening (7% versus 24% versus 42% for AHCWR >20%, 15%-20%, and <15%, respectively; P=0.004). Leaflet billow volume increased exponentially with decreasing AHCWR in patients without chordal rupture (r(2)=0.66, P<0.0001). MR severity correlated strongly with leaflet billow volume (r(2)=0.74, P<0.0001) and inversely with AHCWR (r(2)=0.44, P<0.0001). In contrast, annulus dilatation but not flattening occurred in nonprolapse MR patients. An AHCWR <15% (odds ratio=7.1; P=0.0004) was strongly associated with significant MR in mitral valve prolapse.

CONCLUSION

Flattening of the annular saddle shape is associated with progressive leaflet billowing and increased frequencies of chordal rupture and may be important in the pathogenesis of MR in mitral valve prolapse.

Relation of mitral valve morphology and motion to mitral regurgitation severity in patients with mitral valve prolapse

Background

Mitral valve thickness is used as a criterion to distinguish the classical from the non-classical form of mitral valve prolapse (MVP). Classical form of MVP has been associated with higher risk of mitral regurgitation (MR) and concomitant complications. We sought to determine the relation of mitral valve morphology and motion to mitral regurgitation severity in patients with MVP.

Methods

We prospectively analyzed transthoracic echocardiograms of 38 consecutive patients with MVP and various degrees of MR. In the parasternal long-axis view, leaflets length, diastolic leaflet thickness, prolapsing depth, billowing area and non-coaptation distance between both leaflets were measured.

Results

Twenty patients (53%) and 18 patients (47%) were identified as having moderate to severe and mild MR respectively (ERO = 45 ± 27 mm² vs. 5 ± 7 mm², p < 0.001). Diastolic leaflet thickness was similar in both groups (5.5 ± 0.9 mm vs. 5.3 ± 1 mm, p = 0.57). On multivariate analysis, the non-coaptation distance (OR 7.9 per 1 mm increase; 95% CI 1.72-37.2) was associated with significant MR. Thick mitral valve leaflet as traditionally reported (≥ 5 mm) was not associated with significant MR (OR 0.9; 95% CI 0.2-3.4).

Conclusions

In patients with MVP, thick mitral leaflet is not associated with significant MR. Leaflet thickness is probably not as important in risk stratification as previously reported in patients with MVP. Other anatomical and geometrical features of the mitral valve apparatus area appear to be much more closely related to MR severity.

Cibenzoline attenuates systolic anterior motion of the mitral valve after mitral valvoplasty

We report a patient in whom severe hemodynamic instability occurring after mitral valvoplasty (MVP) was successfully treated with cibenzoline. Left ventricular outflow tract obstruction (LVOTO) with mitral regurgitation (MR) resulting from the systolic anterior motion (SAM) of the mitral valve that occurs after MVP often leads to hemodynamic collapse. Patients who develop SAM after MVP have been managed with intravenous volume loading, reduction/discontinuation of inotropic drugs, and with increased afterload, but these strategies were often ineffective. Cibenzoline decreased myocardial contraction, attenuated SAM, and improved hemodynamics in our patient. We recommend that cibenzoline be administered before further surgical manipulation is considered for patients who develop SAM after MVP.

A short-acting beta-blocker, landiolol, attenuates systolic anterior motion of the mitral valve after mitral valve annuloplasty

Here, we describe three patients with severe hemodynamic instability after mitral valve annuloplasty (MVP) who were treated successfully using a new ultra-short-acting beta-blocker, landiolol hydrochloride. When systolic anterior motion (SAM) of the mitral valve occurs after MVP, left ventricular outflow tract obstruction (LVOTO) and mitral regurgitation (MR) often lead to hemodynamic collapse. Treatment of SAM is very difficult, and transfusion, or the reduction/discontinuation of catecholamine or vasopressor administration, is often ineffective. In our three patients, landiolol hydrochloride decreased the heart rate, markedly attenuated SAM, and improved the hemodynamics. We recommend that landiolol be administered before further surgical manipulation is considered in patients with SAM after MVP.

Etiologic classification of degenerative mitral valve disease: Barlow's disease and fibroelastic deficiency

Barlow's disease and fibroelastic deficiency are the two dominant forms of degenerative mitral valve disease and have unique differentiating characteristics on clinical and echocardiographic assessment. Preoperative differentiation of patients by both cardiologists and surgeons is important because the techniques, surgical skill, and expertise required to achieve a repair vary among these etiological subsets. Barlow's patients often have multiple complex lesions, thus high rates of repair are only likely to be achieved by a reference mitral valve repair surgeon. In contrast, many forms of fibroelastic disease should be repaired at a high rate by experienced general cardiac surgeons. In this article, we highlight the differentiation of Barlow's disease and fibroelastic deficiency.

Catheter-based modification of heart valve diseases: from experimental to clinical application

Efforts to modify cardiac valve defects using catheter-based techniques are increasing at the present time. We present observations on cardiac valve morphology and disease and review the progress being made to address valve defects with these innovative methods. Some new procedures developed through animal experimentation have already been put to use in clinical practice, but the newness of these techniques and the small number of cases in which they have been applied to date precludes an evaluation of their long-term durability. Although at the present time cardiac surgery remains the standard for treating most cases of valve disease, in certain situations a catheter-based treatment might provide a reasonable alternative, even if only temporary, especially for individuals with serious disease who are not suitable candidates for surgery.

Association between urokinase-plasminogen activator gene T4065C polymorphism and risk of mitral valve prolapse

BACKGROUND

Abnormalities of collagen and elastic fibers were found in floppy mitral valves (FMV). Urokinase-plasminogen activator (PLAU) was suggested to be involved in the pathogenesis of elastin and collagen degradation in arterial aneurysm. The role of PLAU genetic variant in mitral valve prolapse (MVP) has not been studied. We, therefore, performed a case-controlled study investigating the possible relation between the PLAU gene polymorphisms and risk of MVP in Taiwan Chinese.

METHODS

We studied 100 patients with MVP diagnosed by echocardiography and 106 age- and sex-matched normal control subjects. The T4065C and T3995C polymorphisms of the PLAU gene were identified by polymerase chain reaction (PCR)-based restriction analysis.

RESULTS

There was a significant difference in either the genotype distribution or allelic frequencies between MVP cases and controls for PLAU gene T4065C polymorphism (P = 0.0001 and 0.0002, respectively). An odds ratio for risk of MVP associated with PLAU T4065C TC genotype was 6.03 (95% confidence interval 2.11-14.83). An odds ratio for risk of MVP associated with PLAU T4065C T allele was 4.99 (95% confidence interval 1.93-12.91). There was no significant difference in either the genotype distribution or allelic frequencies between MVP cases and controls for PLAU T3995C polymorphism. Further categorization of the MVP patients into mild and severe subgroups revealed no statistical difference between these two subgroups for PLAU T4065C and T3995C polymorphisms.

CONCLUSIONS

This study shows that patients with MVP have a higher frequency of PLAU T4065C TC genotype and T allele that supports a role of the PLAU T4065C polymorphism in determining the risk of MVP among the Chinese population in Taiwan.

Association between COL3A1 collagen gene exon 31 polymorphism and risk of floppy mitral valve/mitral valve prolapse

BACKGROUND

Collagen structure is a key element in mitral valves. Collagen defects were proposed as the primary events causing floppy mitral valves (FMV). The role of collagen genetic variant in floppy mitral valve/mitral valve prolapse (FMV/MVP) has not been well studied. The purpose of this study is to investigate the possible relationship between the collagen gene polymorphisms and risk of FMV/MVP among the Chinese population in Taiwan.

METHODS

We studied 100 patients with FMV/MVP diagnosed by echocardiography and 243 age- and sex-matched normal control subjects. The polymorphisms of exon 31 and exon 52 of the collagen type III-alpha1 gene (COL3A1) were identified by polymerase chain reaction (PCR)-based restriction analysis.

RESULTS

There was a significant difference in either the genotype distribution (P<0.0001) or allelic frequencies (P<0.0001) between FMV/MVP cases and controls for COL3A1 exon 31 polymorphism. An odds ratio for risk of FMV/MVP associated with COL3A1 exon 31 GG genotype was 7.42 (95% confidence interval 4.40-12.52). An odds ratio for risk of FMV/MVP associated with COL3A1 exon 31 G allele was 2.28 (95% confidence interval 1.57-3.29). There was no significant difference in the distribution of COL3A1 exon 52 genotypes (P=0.31) and allelic frequencies (P=0.32) between FMV/MVP cases and controls. Further categorization of the FMV/MVP patients into mild and severe subgroups revealed no statistical difference from the controls for exon 31 or exon 52 polymorphism.

CONCLUSIONS

This study shows that patients with FMV/MVP have higher frequency of COL3A1 exon 31 GG genotype that supports a role of the COL3A1 exon 31 polymorphism in determining the risk of FMV/MVP among the Chinese population in Taiwan.

Lack of association between perlecan gene intron 6 BamHI polymorphism and risk of mitral valve prolapse in Taiwan Chinese

Abnormalities of proteoglycan, collagen, and elastic fibers were found in floppy mitral valves. Perlecan is one of the three major classes of heparan sulfate proteoglycans within the cardiovascular system. The role of perlecan genetic variant in mitral valve prolapse (MVP) has not been studied. We therefore performed a case-controlled study investigating the possible relation between the perlecan gene intron 6 BamHI polymorphism and MVP among the Chinese population in Taiwan. We studied 100 patients with MVP diagnosed by echocardiography and 100 age- and sex-matched normal control subjects. The perlecan gene intron 6 BamHI polymorphism was identified by polymerase chain reaction-based restriction analysis. There were no significant differences in either the genotype distribution or allelic frequencies between MVP cases and controls for perlecan gene intron 6 BamHI polymorphism (P = 0.20 and 0.76, respectively). Further categorization of the MVP patients into mild and severe subgroups also revealed no statistical difference from controls for perlecan gene intron 6 BamHI polymorphism. It is concluded that perlecan gene intron 6 BamHI polymorphism is not a suitable genetic marker of MVP in Taiwan Chinese.

Mitral valve prolapse in the general population: the benign nature of echocardiographic features in the Framingham Heart Study

OBJECTIVE

The aim of this study was to examine the echocardiographic features and associations of mitral valve prolapse (MVP) diagnosed by current two-dimensional echocardiographic criteria in an unselected outpatient sample.

BACKGROUND

Previous studies of patients with MVP have emphasized the frequent occurrence of echocardiographic abnormalities such as significant mitral regurgitation (MR) and left atrial (LA) enlargement that are associated with clinical complications. These studies, however, have been limited by the use of hospital-based or referral series.

METHODS

We quantitatively studied all 150 subjects with possible MVP by echocardiography and 150 age- and gender-matched subjects without MVP from the 3,491 subjects in the Framingham Heart Study. Based on leaflet morphology, subjects were classified as having classic (n = 46), nonclassic (n = 37), or no MVP.

RESULTS

Leaflet length, MR degree, and LA and left ventricular size were significantly but mildly increased in MVP (p < 0.0001 to 0.004), with mean values typically within normal range. Average MR jet area was 15.1 +/- 1.4% (mild) in classic MVP and 8.9 +/- 1.5% (trace) in nonclassic MVP; MR was severe in only 3 of 46 (6.5%) subjects with classic MVP, and LA volume was increased in only 8.7% of those with classic MVP and 2.7% of those with nonclassic MVP.

CONCLUSIONS

Although the echocardiographic characteristics of subjects with MVP in the Framingham Heart Study differ from those without MVP, they display a far more benign profile of associated valvular, atrial, and ventricular abnormalities than previously reported in hospital- or referral-based series. Therefore, these findings may influence the perception of and approach to the outpatient with MVP.

The challenge of defining normality for human mitral and aortic valves: geometrical and compositional analysis

Advances in digital imaging technology and in tools for obtaining detailed quantitation of morphological features have facilitated a new approach to pathological assessment of many tissues, including heart valves. In the present study, we quantitatively examined the tissue geometry and composition of structurally normal mitral and aortic valves removed at autopsy or surgery from patients aged 15-84 years. Through univariate analyses of quantitative variables, we have determined which features change distinctively with age. The anterior mitral valve leaflet (AMV) underwent a statistically significant decrease in area of the valve proper and an increase in the number of superficial tissue accumulations called onlays as the patients aged. For all geometric variables measured in the aortic valve, increases were seen with age, leading to a thicker valve, with enlargement of the valve proper and onlays, and with changes in the number of onlays. The mitral valve proper, composed largely of collagen in younger individuals, showed significant increases in glycosaminoglycans and elastin and a relative decrease in collagen with age. The compositional characteristics of the aortic valve proper were similar to those of the mitral valve, with a dramatic relative increase in elastin and a decrease in collagen with age. Valve onlays, when present, were similar in composition to the valve proper for both valves. Our findings regarding normal valve tissue composition, when taken in the context of geometrical features, and together with evidence of age-related changes in the relative amounts of specific constituents, provide a basis on which to analyze human heart valves affected by various known or putative diseases.

Floppy Mitral Valve, Mitral Valve Prolapse, and Mitral Valvular Regurgitation

It is well recognized that the floppy mitral valve (FMV) complex is the central issue in the FMV, mitral valve prolapse (MVP), and mitral valvular regurgitation (MVR) story. MVP associated with the FMV results from the systolic movement of portions or segments of the FMV complex into the left atrium (LA). Prolapse of the FMV results in unique forms of mitral valvular dysfunction and MVR. When the FMV is recognized as the basic point of reference, diagnostic and nosologic characterizations are simplified. Each of the consequences of FMV dysfunction--MVP, MVR, and FMV surface phenomena--are dynamic entities and contribute to the symptoms and clinical course in this patient population. Although MVP may occur in the absence of a FMV in individuals with small left ventricular (LV) volume, hyperdynamic, or hypercontractile LV, we do not consider this phenomenon as part of FMV/MVP/MVR. The natural history of the FMV/MVP/MVR is long, and understanding the life history requires long-term follow-up with serial evaluations. Identification of those individuals with FMV/MVP whose symptoms are related to, or associated with, autonomic nervous system dysfunction (ie, the FMV/MVP syndrome) is important, as this distinction has diagnostic and therapeutic implications. In general, patients with FMV/MVP should receive antibiotic prophylaxis for infective endocarditis. Data suggest that therapy with angiotensin-converting enzyme inhibitors for FMV/MVP and significant MVR may slow the natural regression of the disease. Surgical therapy should be considered in patients with significant MVR and symptoms related to MVR. Explanation for the nature of these symptoms, reassurance, avoidance of volume depletion, catecholamines or other cycle-AMP stimulants and a regular exercise program constitute the basic principles of management for patients with FMV/MVP syndrome.

Echocardiographic assessment of the mechanisms of correction of bileaflet prolapse causing mitral regurgitation with only posterior leaflet repair surgery

Recent data suggest that posterior leaflet repair alone corrects mitral regurgitation in patients with bileaflet prolapse and normal anterior chordae. The purpose of this study was to use echocardiography to define the anatomic differences between posterior and bileaflet prolapse and to determine if posterior leaflet repair alone leads to correction of bileaflet prolapse. We studied patients who underwent quadrangular resection of the posterior mitral valve leaflet to treat bileaflet prolapse (group I, n = 20) or isolated posterior leaflet prolapse (group II, n = 20). Echocardiographic characteristics were compared before and after the procedure. There were no differences in the left ventricular end-diastolic or end-systolic dimensions or function between the 2 groups. However, anterior leaflet length was greater in patients with bileaflet prolapse (3.3 +/- 0.6 cm vs 2.6 +/- 0.4 cm, p = 0.003). In group I, posterior leaflet repair changed anterior leaflet displacement from -0.8 +/- 0.2 to 0.5 +/- 0.4 cm (p <0.001) and posterior leaflet displacement from -0.8 +/- 0.3 cm below to 0.5 +/- 0.4 cm (p <0.001) in front of the mitral annular plane. In group II, anterior leaflet displacement was unchanged from 0.2 +/- 0.1 to 0.3 +/- 0.2 cm (p = 0.22), whereas posterior leaflet displacement changed from -0.7 +/- 0.2 to 0.4 +/- 0.2 cm (p <0.001). Thus, patients with bileaflet prolapse and no ruptured chords have excessive anterior leaflet length. In such patients, posterior leaflet repair alone corrects anterior and posterior leaflet prolapse.

Clinical characteristics of a familial inherited myxomatous valvular dystrophy mapped to Xq28

OBJECTIVES

The purpose of this study was to describe the phenotypic characteristics of an inherited myxomatous valvular dystrophy mapped to Xq28.

BACKGROUND

Myxomatous valve dystrophies are a frequent cause of valvular diseases, the most common being idiopathic mitral valve prolapse. They form a group of heterogeneous diseases difficult to subclassify. The first mapping of the gene for a myxoid valvular dystrophy to Xq28 allowed investigation of the phenotype of affected members in a large family and characterization of the disease.

METHODS

Among the 318 members in the pedigree, 89 agreed to participate in this study. Phenotypic characteristics were investigated using clinical examination, transthoracic echocardiography and biological analysis (F.VIII activity). Genetic status was based on haplotype analysis.

RESULTS

Among 46 males, 9 were hemizygous to the mutant allele and had an obvious mitral and/or aortic myxomatous valve defect, and 4 had undergone valvular surgery. All had typical mitral valve prolapse associated in six cases with moderate to severe aortic regurgitation. The valve defect cosegregated with mild hemophilia A (F.VIII activity = 0.32 +/- 0.05). The 37 remaining males had normal valves and normal F.VIII activity. Heterozygous women were identified on the basis of their haplotypes. Among the 17 women heterozygous to the mutant allele, moderate mitral regurgitation was present in 8, associated with mild mitral valve prolapse in 1 and aortic regurgitation in 3, whereas 2 women had isolated mild aortic regurgitant murmur. In heterozygotes, the penetrance value was 0.60 but increased with age.

CONCLUSION

X-linked myxomatous valvular disease is characterized by mitral valve dystrophy frequently associated with degeneration of the aortic valves affecting males and, to a lower severity, females. The first localization of a gene for myxomatous valvular diseases is the first step for the subclassification of these diseases.

Management of mitral regurgitation. Optimal timing for surgery

Chronic mitral regurgitation is a progressive disorder that can produce myocardial dysfunction in the absence of symptoms. Improvements in surgical techniques have resulted in earlier intervention, at times in asymptomatic patients. This article discusses the factors that influence prognosis, reviews the evidence supporting earlier intervention and provides guidelines for the management of patients with this lesion.