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Lack of association between thyroid function and mitral valve prolapse in Graves' disease.

1. To determine whether the association between mitral valve prolapse and Graves' disease is related to thyroid function, three groups of individuals were studied: 16 patients with Graves' disease and hyperthyroidism (hyperthyroid: T4 greater than 11.5 micrograms/100 ml), 16 patients with Graves' disease without hyperthyroidism (euthyroid: T4 less than 11.5 micrograms/100 ml), and 40 healthy individuals. The three groups were similar in age, sex distribution, and anthropometrical characteristics. 2. All patients were evaluated clinically and by M-mode and two-dimensional echocardiography to determine the presence of mitral valve prolapse. 3. The frequency of mitral valve prolapse was similar in the hyperthyroid (31%) and euthyroid patients (25%), but was higher than in the normal individuals (5%). The frequency of systolic murmur was higher in the hyperthyroid patients (75%) than the euthyroid patients (19%) or the normal subjects (0%); however, the presence of a murmur was not associated with mitral valve prolapse. Hyperthyroid (13%) and euthyroid (13%) patients had a higher frequency of clicks than the normal individuals (0%), and the presence of click was associated with mitral valve prolapse. 4. Although patients with Graves' disease have a higher frequency of mitral valve prolapse, this is not associated with thyroid function. The presence of a click but not the presence of a systolic murmur may be a clinical indicator of mitral valve prolapse in Graves' disease.

Adult↗

Structural characterization of the chordae tendineae in native porcine mitral valves.

BACKGROUND: This study was aimed to characterize the different mitral valve chordae tendineae to provide additional understanding of their function. METHODS: Mitral valve chordae tendineae from fresh porcine hearts were stained for collagen and elastin using either a Verhoeff and van Gieson stain or Verhoeff light green stain. Cellular distribution was determined using a hematoxylin and eosin stain. Immunohistochemistry was used to verify the findings of vasculature. Biochemical assays were performed to quantify DNA, collagen, and elastin content of each of the six different types of chordae tendineae. RESULTS: Blood vessels were observed in the longitudinal and circumferential directions of the chordae. The strut chordae on the anterior leaflet of the mitral valve showed an increased degree of vascularization compared with the other chordae. All chordae had an inner layer characterized by a high concentration of collagen and an outer layer that was mostly elastin with interwoven collagen fibers. The collagen microstructure was characterized by directional crimping. Hematoxylin and eosin staining showed fibroblasts evenly distributed throughout the inner and outer layer of the chordae tendineae. Quantitative analysis showed significantly higher levels of DNA and collagen content in the anterior and posterior marginal chordae compared with the other chordae. CONCLUSIONS: The chordae tendineae were seen to have different microstructures according to chordal type. The presence of vessels characterized the chordae tendineae as complex living components that work in coordination with the papillary muscles and mitral valve leaflets to prevent mitral valve prolapse and regurgitation. They may also function to supply nutrients to the valve leaflets.

Animals↗

Comparative value of transthoracic and transoesophageal echocardiography before balloon dilatation of the mitral valve.

OBJECTIVE: To assess the relative merits of transthoracic and transoesophageal echocardiography before balloon dilatation of the mitral valve. DESIGN: Transthoracic and transoesophageal echocardiograms were prospectively performed in 35 patients being considered for balloon dilatation of the mitral valve. Echocardiograms were analysed for image quality, the assessment of valve morphology, the detection of left atrial thrombus, and the assessment of mitral regurgitation and other valvar pathology. PATIENTS: 35 consecutive patients with symptomatic dominant mitral stenosis. INTERVENTIONS: 30 eventually underwent balloon dilatation of the mitral valve by the Inoue technique. Five patients had mitral valve replacement. MAIN OUTCOME MEASURES: Echocardiographic and surgical detection of left atrial thrombus and successful, uncomplicated balloon dilatation of the mitral valve. RESULTS: Left atrial thrombus was detected in 1/35 patients by transthoracic studies compared with 6/35 from transoesophageal studies. Otherwise both techniques gave comparable results. Thrombus was confirmed at mitral valve replacement in five patients. Successful dilatation of the mitral valve was performed in 30 patients. CONCLUSIONS: Transthoracic echocardiography is a useful screening procedure but transoesophageal echocardiography is mandatory before balloon dilatation of the mitral valve for the detection of left atrial thrombus.

Adult↗

Importance of leaflet elongation in causing systolic anterior motion of the mitral valve.

BACKGROUND AND AIMS OF THE STUDY: There is growing evidence for mitral leaflet elongation in patients with hypertrophic cardiomyopathy. Such elongation could predispose to systolic anterior motion (SAM) of the mitral valve by increasing leaflet mobility and providing a geometry that promotes this condition. METHODS: To test this postulate, five porcine mitral valves were studied in a physiologic left heart pulsatile flow duplicator. They were elongated with patches sutured to the basal posterior leaflet (three sizes per valve) or anterior leaflet (basal, middle, or distal). Each geometry was studied with normal papillary muscle position and with anterior and inward displacement, as seen in hypertrophic cardiomyopathy, to shift the leaflets into the outflow stream. RESULTS: Four points became clear. 1) Leaflet elongation promoted the development of SAM in response to papillary muscle displacement by creating long overlapping residual leaflets capable of moving anteriorly. 2) Posterior leaflet elongation also promoted SAM by shifting leaflet coaptation anteriorly, with progressive increases in SAM. 3) Basal and mid-anterior leaflet elongation caused SAM with prolapse; distal anterior leaflet elongation created SAM with a mobile flap (leaflet elongation without papillary muscle displacement created prolapse). 4) Residual leaflet length correlated well with total leaflet length (r = 0.87-0.98 for each valve), and the degree of SAM in turn correlated well with residual leaflet length (r = 0.62-0.98 for individual valves). CONCLUSIONS: Mitral leaflet elongation, by increasing the residual leaflet length and leaflet mobility, can play an important role in promoting SAM in response to outflow forces, as demonstrated by prospectively altering leaflet length. These findings are consistent with recent observations that reducing leaflet redundancy and posterior leaflet height can reduce obstructive SAM following mitral valve repair in patients with mitral valve prolapse and help relieve obstruction in patients with hypertrophic cardiomyopathy and enlarged leaflets.

Cardiomegaly↗

[Comparison of preoperative and postoperative hemodynamic parameters in replacement or reconstruction of the mitral valve in ischemic dilated cardiomyopathy].

INTRODUCTION: Ischemic mitral insufficiency is a clinical syndrome described as a consequence of the coronary artery disease where the basic problem is blood regurgitation between the left ventricle and left atrium following mitral annulus dilatation. Mitral regurgitation occurs in different degrees during the natural evolution of the ischemic heart disease. The main reason for the existence of mitral regurgitation is global deterioration in the left ventricle geometry as a consequence of myocardial infarction or/and left ventricle dilatation. Surgical correction of this problem is possible by simultaneous correction of mitral insufficiency (repair or replacement) and complete myocardial revascularisation. MATERIAL AND METHODS: Complete hemodynamic monitoring was followed by Swan-Ganz catheter including: central venous pressure, mean pulmonary artery pressure, pulmonary capillary wedge pressure, cardiac output, cardiac index and pulmonary vascular resistance. All surgical procedures were performed in extracorporeal circulation (ECC) with membrane oxygenator using moderate systemic hypothermia and transseptal surgical approach to mitral valve. Hemodynamic parameters were followed before and after ECC, immediately after surgery and during the first 48 hours after operation in the intensive care unit. In 88 patients posterior semicircular annuloplasty by N. Radovanović was performed whereas in 13 patients mitral valve replacement was done. RESULTS: There is a great, statistically significant hemodynamic improvement after the surgical procedure and during the continuous 48 hours monitoring in the intensive care unit no matter if mitral repair or replacement was done. No statistically significant difference was recorded between these two groups considering that the hemodynamic improvement is very similar. DISCUSSION: Simultaneous surgical procedures, including myocardial revascularization, mitral and usually consecutive tricuspid insufficiency correction, are a very common surgical problem with higher operative risk than isolated coronary bypass procedures. In 88 cases where mitral reconstruction was possible, posterior semicircular reductive annuloplasty was performed. Thus mitral annulus area reduction is achieved preserving its physiologic shape and avoiding rigidity. Mitral valve replacement includes implantation of the latest generation of bileaflet valve prosthesis and operative technique that preserves subvalvular apparatus to maintain myocardial contractility as much as possible. This policy and also good immediate postoperative care, improve the hemodynamic status in both groups. CONCLUSION: All hemodynamic parameters followed by ECC and 48 hours in the intensive care unit were significantly improved no matter whether mitral reconstruction or replacement was done. There is no statistically significant difference in hemodynamic parameters and clinical improvement between these two groups. Carefully chosen operative tactic and techniques as well as good preoperative and postoperative care may explain these very good results.

Cardiomyopathy, Dilated↗

Classification of the radiological morphology of the mitral valve. Differentiation between true and pseudoprolapse.

The morphology of the mitral valve apparatus was assessed on 100 normal left ventriculograms. Four distinct types of mitral valve were identified according to the position of the mitral fulcrum (the point of attachment of the leaflets to the annulus) and the configuration of the adjacent left ventricular wall (left ventricular fornix) during diastole. Types I and II closely simulated prolapse of the mitral valve (pseudoprolapse) in the right anterior oblique projection during the ejection period. Measurements showed that contraction of the ventricle failed to reduce the diameter of the mitral valve annulus in 26 per cent of normal left ventricles.

Angiocardiography↗

Fibromuscular dysplasia of small coronary arteries and fibrosis in the basilar ventricular septum in mitral valve prolapse.

The mechanism of sudden cardiac death in patients with mitral valve prolapse is poorly understood. Twenty-four hearts from patients with mitral valve prolapse who suddenly died (mean age 34 +/- 8 years) and 16 trauma control hearts (mean age 30 +/- 7 years) were histologically studied. Dysplasia of the atrioventricular nodal artery was present in 18 of 24 hearts with mitral valve prolapse and four of 16 controls hearts (p = 0.003). The degree of luminal narrowing, as morphometrically measured, was significantly greater in hearts with mitral valve prolapse (p = 0.003). The degree of fibrosis in the base of the ventricular septum, as calculated by computerized morphometry, was greater in hearts with mitral valve prolapse (p = 0.0002) and independent of age, sex, and heart weight (p = 0.005). We conclude that arterial dysplasia in mitral valve prolapse may contribute to sudden cardiac death mediated by ventricular fibrosis.

Adult↗

Transesophageal echocardiographic assessment of systolic mitral leaflet displacement among patients with mitral valve prolapse.

Though qualitative transthoracic echocardiographic criteria for abnormal systolic leaflet motion are widely accepted as diagnostic characteristics of mitral valve prolapse, transesophageal echocardiographic criteria have not been evaluated against such a standard. Because transesophageal imaging planes are not identical to transthoracic imaging planes, validation of transesophageal echocardiographic criteria for mitral valve prolapse is needed. Eleven patients with mitral valve prolapse (based on physical findings and transthoracic echocardiographic criteria) and 11 healthy persons underwent prospective transesophageal echocardiography in two orthogonal imaging planes. Measurements of maximal leaflet displacement superior to the annular hinge points and mitral prolapse area subtended by the displaced mitral leaflets and the chord connecting the annular hinge points were performed in triplicate and averaged by a blinded observer. Though maximal systolic leaflet displacement was greater among patients with mitral valve prolapse than healthy subjects for both the transesophageal four-chamber (0.66+/-0.39 cm versus 0.05+/-0.11 cm, p < 0.001) and two chamber views (0.57+/-0.44 cm versus 0.20+/-0.25 cm, p < 0.04), no unique value differentiated patients with from those without mitral valve prolapse. Mitral prolapse area was greater for patients with mitral valve prolapse than for healthy subjects in both transesophageal four-chamber (1.23+/-1.18 cm2 versus 0.03+/-0.06 cm2, p < 0.02) and two-chamber views (1.73+/-1.65 cm2 versus 0.21+/-0.31 cm2, p < 0.02). Whereas a mitral prolapse area of 0.20 cm2 uniquely differentiated patients with from those without mitral valve prolapse in the four-chamber view, data overlap prevented determination of a similar diagnostic criterion for the two-chamber view. The difficulty in defining quantitative transesophageal echocardiographic criteria for mitral valve prolapse based on leaflet displacement alone suggested that the simple qualitative observation of leaflet displacement above the annular hinge points should not be used as a defining morphologic criterion for mitral valve prolapse.

Adult↗

[Atrial fibrillation in a long-term follow-up after mitral valve replacement].

UNLABELLED: The aim of the study was to analyse cardiac rhythm after mitral valve replacement and to define pre-operative predictive factors for persistence of atrial fibrillation. MATERIAL AND METHODS: The study group consisted of 76 consecutive pts (54 F, 22 M), mean age 54.8 +/- 8.2 (38-71) years in whom mitral valve replacement was performed due to mitral stenosis (15 pts), regurgitation (18 pts) or mixed lesion (43 pts). The prevalence of AF after the procedure was analysed with relation to age, gender and the following preoperative echocardiographic parameters: left atrial size, mitral valve area, mitral regurgitation, tricuspid regurgitation and left ventricular ejection fraction. RESULTS: Chronic AF was present in 51 pts (67.1%) before the procedure and in 34 pts (44.7%) after 17.3 +/- 11.9 months (6-46) follow-up, p<0.005. Patients with AF after operation had larger left atrium size (58.6 +/- 10.9 vs 51.3 +/- 10.1 mm, p<0.005) and lower ejection fraction (53.8 +/- 7.9 vs. 59.9 +/-8.4%, p<0.01) as compared with pts in sinus rhythm. Among 51 pts with preoperative chronic AF, 21 pts recovered to sinus rhythm (subgroup I) and 30 pts remained in AF (subgroup II) after operation. The only significant differences between subgroup I and II were: higher prevalence of mitral regurgitation (85.7 vs 60%, p<0.05), larger mitral valve area (1.4 +/- 0.3 vs 1.1 +/- 0.6 cm2, p<0.025) and higher ejection fraction (58.9 +/- 7.3 vs. 53.4 +/- 8.4%, p<0.025) in subgroup I. CONCLUSIONS: 1. The prevalence of AF diminishes significantly after mitral valve replacement. 2. Patients with pure mitral stenosis are at higher risk of remaining in AF after operation. 3. Preoperative left atrial dimension and LV ejection fraction are the most important predictive parameters for persistence of AF.

Adult↗

Collagen synthesis is upregulated in mitral valves subjected to altered stress.

Mitral regurgitation (MR) and abnormal ventricular wall motion (AVWM) are two cardiac conditions that may increase mitral valve (MV) stresses. Theoretically, increased stress could induce damaging MV tissue alterations. These alterations may impair the preferred option of repair, and mandate replacement. It is hypothesized that MV collagen synthesis is upregulated in response to MR and AVWM. To test this hypothesis in a pilot study, an ischemic sheep model (n = 8) was employed. Four sheep underwent selective coronary artery ligation to infarct a papillary muscle, which resulted in MR. Two other sheep underwent similar coronary ligation to create AVWM. As controls, two sheep underwent sham surgery (no ligation). Sheep were killed 4 and 8 weeks post operatively and their MVs were sectioned. Sections were stained with an antibody (SP1.D8, University of Iowa) to procollagen I (precursor to collagen I). The percent area of procollagen stain present present was measured by image analysis (Optimas Corporation) and used as an indicator of collagen synthesis. Procollagen results indicated that MV collagen synthesis was upregulated by factor of 1.8 in both the MR and AVWM groups versus controls. In addition, results showed greater upregulation in anterior leaflets compared with posterior leaflets in both infarct groups. These results indicate that MV collagen synthesis is upregulated in response to MR and AVWM.

Animals↗

Myxoma of the mitral valve.

A case of myxoma of the mitral valve is reported. The clinical features were indistinguishable from left atrial myxoma with prolapse through the mitral valve. Because of the known tendency for these tumours to recur it was treated by wide excision which necessitated replacement of the mitral valve.

Adult↗

In vitro analysis of mechanisms of balloon valvuloplasty of stenotic mitral valves.

Preliminary reports indicate that percutaneous balloon valvuloplasty is efficacious for treatment of mitral stenosis. The present study was designed to evaluate whether anatomic features of stenotic mitral valves in older adults affect the efficacy of balloon valvuloplasty and to determine the mechanism by which increased orifice area is accomplished. Fifteen mitral valves excised intact at the time of mitral valve replacement from patients with no more than 2+/4+ mitral a regurgitation were selected for study. Balloon valvuloplasty was performed using a sequence of dilation catheters with balloons 18 to 25 mm in inflated diameter. Mitral valve area, measured with a conical valve sizer, increased from 0.71 +/- 0.06 cm2 (mean +/- standard error of the mean) to 1.77 +/- 0.19 cm2 (p less than 0.0001) after valvuloplasty, resulting in an increase in calculated orifice area of 185 +/- 27% (range 34 to 407%). The increase in calculated orifice area correlated inversely with orifice area before valvuloplasty (r = -0.57; p = 0.026), but was unrelated to extent of calcific deposits on the prevalvuloplasty x-ray of the excised mitral valve. Gross examination together with x-ray analysis after valvuloplasty revealed that the mechanism of balloon valvuloplasty in each case involved commissural splitting, including splits through heavily calcified commissures, without grossly apparent detachment of tissue fragments. These findings suggest that balloon valvuloplasty augments the functional mitral valve orifice area in a manner analogous to standard surgical commissurotomy, and balloon valvuloplasty is likely to be efficacious for a wide spectrum of adult mitral valvular stenosis, including severe stenosis with extensive calcific deposits.

Adult↗

Mitral valve reconstruction in elderly, ischemic patients.

The role of mitral valve reconstruction is controversial in elderly patients with concurrent ischemic heart disease owing to technical difficulty, prolonged operative times, high mortality, and possible residual mitral regurgitation. However, mitral reconstruction could be most beneficial in this age group due to preservation of left ventricular function, avoidance of anticoagulation, or repeat operation for bioprosthetic degeneration. We studied the outcome of mitral valve reconstruction in 100 consecutive elderly ischemic patients 65 years or older (mean = 73 years; range, 65 to 86 years) operated on between October 1990 and May 1995. Preoperatively all patients were New York Heart Association (NYHA) class III or IV with an ejection fraction of 32 +/- 2%. All patients underwent primary coronary bypass grafting (2.7 +/- 0.2 grafts) and had a flexible mitral annuloplasty ring inserted. Additionally, 54 patients required further complex mitral repairs. All patients had 4+ mitral regurgitation by transesophageal echocardiography prior to operation. After mitral reconstruction, no patient had more than 1+ regurgitation, while most had none and no systolic anterior leaflet motion was noted. There were 4 early (30 day) deaths (4%) and 6 late deaths (6%) at a mean follow-up of 25 months. Patient morbidity has included episodes of mild congestive heart failure (nine), transient ischemic attack (one), endocarditis (one), and respiratory failure (five). There have been one early and two late reoperations for mitral valve replacement. All remaining patients are in NYHA class I or II. While longer-term follow-up is mandatory, coronary bypass grafting and mitral valve reconstruction in the elderly can be accomplished with acceptable surgical mortality and morbidity, yielding reliable improvement in symptoms and quality of life.

Aged↗

Simplified method for reoperation on the mitral valve.

Reoperation on the mitral valve is becoming more common because of the degeneration of bioprosthetic valves, endocarditis, and malfunction or thrombosis of mechanical valves. We advocate a technique that transforms a technically difficult operation into one that is much less tedious, time-consuming, and dangerous than reopening a sternal-split operative site the second, third, or fourth time. Favorable experience in 11 patients using right anterolateral thoracotomy without aortic or right atrial cannulation and without aortic cross-clamping or cardioplegia is presented.

Adult↗

Mitral valve aneurysm: clinical features, echocardiographic-pathologic correlations.

Aneurysm of the mitral valve occurs most commonly in association with infective endocarditis of the aortic valve. The probable mechanism of its formation is destruction of the aortic valve which results in a regurgitant jet that strikes the anterior leaflet of the mitral valve, creating a secondary site of infection leading to the development of an aneurysm. Perforation of these aneurysms may occur, resulting in mitral regurgitation and pulmonary edema from a ventricle already volume overloaded from aortic regurgitation. This report describes the clinical and echocardiographic-pathologic findings in five patients with pathologically proven aneurysm of the mitral valve. There are no clinical features that appear specific for this abnormality. The two-dimensional echocardiographic feature that is helpful in the diagnosis is a bulge of the mitral valve leaflet toward the left atrium that persists throughout the cardiac cycle. Preoperative diagnosis is important because a mitral valve aneurysm may produce serious complications and is frequently overlooked during surgery. Repair of the aneurysm may be feasible; otherwise, valve replacement becomes necessary. Careful two-dimensional echocardiographic examination should be done in patients with left-sided infective endocarditis to detect an aneurysm of the mitral valve.

Adult↗

Impact of preoperative left ventricular ejection fraction on postoperative left ventricular remodeling after mitral valve repair for degenerative disease.

BACKGROUND AND AIM OF THE STUDY: Mitral valve repair has been associated with better preservation of left ventricular (LV) function, especially in the setting of degenerative regurgitation. The goal of this study was to evaluate the impact of mitral valve repair on postoperative LV ejection fraction (LVEF) and LV remodeling as determined by LV end-systolic and diastolic diameters. METHODS: A prospective echocardiographic and clinical evaluation of 91 patients undergoing mitral valve repair for degenerative regurgitation between 1993 and 1998 was performed. Patients with normal preoperative LVEF (> or = 50%; group 1, n = 71) were compared with patients with decreased preoperative LVEF (< 50%; group 2, n = 20) one year after mitral valve repair. RESULTS: In group 1 patients, the LVEF was preserved at one year, while the LV end-systolic diameter was significantly reduced from 36 +/- 7 mm to 32 +/- 8 mm (p <0.05). There was a significant improvement in LVEF in group 2 patients (38 +/- 6% preoperative versus 50 +/- 12% at one year, p <0.05). The preoperative LV end-systolic diameter was significantly larger in group 2 patients (47 +/- 9 mm) than in group 1 patients (36 +/- 7 mm) (p <0.001), but decreased to normal values at one year after repair (38 +/- 7 mm, p <0.05). CONCLUSION: There was good preservation of LV function after mitral valve repair in group 1 patients. The LVEF significantly increased towards normal in patients with depressed LV function before repair. The LV systolic diameter was restored to normal within one year of repair, even in patients with poor LV function. Decreased preoperative LV function should not be a contraindication to mitral valve repair in patients with degenerative regurgitation.

Aged↗

[Mitral valve lesions in patients with right ventricular pressure overload: analysis using realtime, two-dimensional echocardiography].

Mitral valve lesions in patients with right ventricular pressure overload, such as pulmonary stenosis, tetralogy of Fallot, and pulmonary hypertension, were studied by real-time, two-dimensional echocardiography, and the following results were obtained. The abnormality observed in the mitral valve was a systolic dislocation of the anterior and posterior mitral leaflets at the coaptation zone. Mitral valve lesions were noted in 16 of 46 cases, i.e. nine of 11 with pulmonary hypertension (82%), four of 20 with tetralogy of Fallot (20%), and three of 15 with pulmonary stenosis (20%). The incidence was highest in patients with pulmonary hypertension. In eight of 16 cases with mitral valve lesions, mitral regurgitation was observed by either left ventriculography or two-dimensional Doppler echocardiography. Mitral valve lesions were always located at the posteromedial commissure of the anterior mitral leaflet. Considering the previous similar reports in secundum atrial septal defect, we attributed the cause of the mitral valve lesions to the same mechanism. No clear relation could be found between the left ventricular deformity index and the incidence of mitral valve lesion. Therefore, we could not conclude about the mode of production of mitral valve lesions occurring in the diseases with right ventricular pressure overload.

Adolescent↗

En face demonstration of a prosthetic mitral valve orifice during left ventriculography.

Direct demonstrate of the orifice of a prosthetic mitral valve was obtained using an en face projection of the mitral valve during left ventriculography. With a dimensional reference and planimetry, the mitral valve area was directly measured. The value for the mitral valve area derived from en face demonstration of the mitral valve during left ventriculography agreed well with valve area estimates obtained by the Gorlin and Gorlin formula and by direct examination of the surgical specimen.

Adult↗