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PubMed1998

Altered collagen concentration in mitral valve leaflets: biochemical and finite element analysis.

BACKGROUND: Ischemic mitral regurgitation or ventricular wall motion abnormalities will alter the stress distribution in the mitral valve. We hypothesize that in response, the regional collagen concentration will be altered and will significantly impact the stress distribution in the mitral valve. METHODS: Two sheep served as normal (sham) controls. Two other sheep had coronary ligation resulting in abnormal ventricular wall motion. Four sheep underwent ligation to infarct the posteromedial papillary muscle, resulting in ischemic regurgitation. After 4 or 8 weeks, the mitral valves were excised, and the anterior leaflet sections were subjected to an assay for collagen concentration. Next, in a finite element model, to simulate changes in collagen concentration, the tissue stiffness was increased by 20%, and then decreased by 20%. In another model, the thickness of the tissue was increased by 20%, and then combined with decreased tissue stiffness. Physiologic loading pressures were applied, and leaflet stress, chordal stress, and coaptation results were analyzed. RESULTS: The average collagen concentration in the normal sheep leaflets was 59.2% (dry weight), 50.6% in the ischemic controls, and 45.8% in the papillary muscle infarct group. Collagen concentration was greatest at the midline and decreased toward the commissures. Increased tissue stiffness resulted in increased leaflet and chordal stresses, as well as reduced coaptation. Decreased stiffness resulted in the opposite. Increased tissue thickness reduced leaflet and chordal stresses, but also reduced coaptation. The combination of increased tissue thickness and decreased stiffness demonstrated the greatest reduction in leaflet and chordal stress, while maintaining normal leaflet coaptation. CONCLUSIONS: The observed changes may demonstrate an early effort to compensate for increased leaflet stress. Microstructural alterations may demonstrate an early effort to compensate for altered physiologic loading to reduce stress and maintain coaptation. It is crucial in repairing or partially replacing thickened tissue that normal geometry and physiology be restored.

Animals↗
PubMed2002

Clinical, echocardiographic, and biomechanical differences in mitral valve prolapse affecting one or both leaflets.

Mitral valve prolapse (MVP) is the most common cause of severe mitral regurgitation necessitating surgical correction. Unileaflet prolapse (ULP), usually involving the posterior leaflet, is more common than bileaflet prolapse (BLP), which is more difficult to repair. Little is known about clinical, echocardiographic, and biomechanical differences between ULP and BLP. In this study, biomechanical testing was performed on mitral valve leaflets and chordae obtained at operation for severe mitral regurgitation. Preoperative clinical characteristics and echocardiographic measurements were obtained on surgical patients (ULP = 88, BLP = 37). Men outnumbered women by a factor of 4:1 in ULP, and by 3:1 in BLP. Patients with BLP were younger (53.2 +/- 1.7 vs 59.5 +/- 1.1 years) than those with ULP, and this difference was greater in women (48.9 +/- 2.5 vs 62.9 +/- 2.2 years). BLP patients were less likely to be hypertensive, and more likely to undergo valve replacement rather than repair. Echocardiography showed that BLP leaflets were longer and thicker than ULP leaflets. The severity of mitral regurgitation was similar in both groups, although ULP patients had a much higher incidence of flail leaflets (45% vs 5% in BLP). Mechanical strength of chordae was greater in BLP than in ULP, although leaflet strength was similar. The increased chordal strength in BLP may be responsible for less flail. In patients with MVP and severe mitral regurgitation requiring surgery, ULP and BLP are distinct entities with substantial differences in the population affected, in echocardiographic manifestations including prevalence of flail, in chordal mechanics, and in the likelihood of surgical repair.

Biomechanical Phenomena↗
PubMed1995

[Correlation between pulmonary vascular changes and hemodynamic parameters during exercise before and after mitral valve surgery].

Sixteen cases with mitral valvular disease were studied with regard to the correlation between pathological changes in the pulmonary vasculature and pulmonary hemodynamics during exercise before and after surgery. In muscular pulmonary arteries obtained by open lung biopsy, medial wall thickness (MWT) was 13.8 +/- 3.2% and intimal thickness (IT) was 37.3 +/- 13.5%. MWT was correlated with IT (r = 0.60, p < 0.05). Wall thickness in pulmonary veins was 8.21 +/- 1.8%. Preoperative mean pulmonary arterial pressure (MPAP) during exercise was 45.9 +/- 9.4 mmHg, and decreased significantly to 38.1 +/- 11.3 mmHg postoperatively. However, in 4 patients, MPAP during exercise increased after surgery. Pulmonary vascular resistance (PVR) during exercise was unchanged before and after surgery (2.74 +/- 1.90 U.M2-->2.69 +/- 1.3 U.M2). MWT was significantly correlated with preoperative MPAP at rest only. In patients showing an increase of MPAP during exercise postoperatively, mean MWT was 16.2% and mean IT was 47.4%. In conclusion our data suggest that postoperative pulmonary hemodynamics does not improve in patients whose MWT exceeds 15% and IT exceeds 40% and that irreversibility may be due to pulmonary vascular lesions.

Adult↗
PubMed2000

Mitral-valve replacement in children under 6 years of age.

OBJECTIVE: In patients with congenital mitral-valve disease, reconstructive surgery is the primary goal. However, in cases with severely dysplastic valves or failed repair, mitral-valve replacement (MVR) is the only option. We analyzed, retrospectively, data of 35 patients younger than 6 years of age, who underwent MVR at our institution. METHODS: Between 1974 and 1997, 35 children underwent MVR. The ages ranged from 2.7 months to 5.5 years (mean=1. 9+/-1.7 years) and body weight varied between 3.2 and 16.7 kg (mean=8.2+/-4 kg). The main indication (57%) for valve replacement was severe mitral-valve insufficiency. Eighteen patients (51%) had undergone at least one previous reconstructive operation (mean=1. 46+/-1.86 years) before the MVR. In 29 cases (83%), mechanical prostheses were implanted. Six patients received a bioprosthesis. The size of the prostheses ranged between 14 and 27 mm. RESULTS: The overall hospital mortality was 17.1% (6/35), and decreased from 33 (1974-1985) to 11.5% (1986-1997). Seven children died late. The actuarial survival after 20 years was 51.2+/-13.3%. Eight patients (23%) required 10 reoperations (8.2%/100 patient-years). Freedom from reoperation at 10 years was 50+/-22%. Valve-related complications were thrombo-embolism (n=2; 1.6%/100 patient-years), hemorrhage (n=1; 0.8%/100 patient-years), structural deterioration (n=3; 2.5%/100 patient-years) and non-structural dysfunction (n=3; 2. 5%/100 patient-years). Follow-up is 96% complete, with a total of 122 patient-years (mean=4.2+/-4.7 years). Eighty six percent of the patients are in New York Heart Association (NYHA) class I, 95% have sinus rhythm and 59% do not need medication. All survivors, except for those who received a bioprosthesis, were placed on a regimen of Phenprocoumon (Marcumar((R))), aiming to maintain the International Normalized Ratio (INR) between 2.5 and 3.5. In one third of these children, self-management of oral anticoagulation was performed either by the patients or their parents. CONCLUSIONS: MVR in small children still carries a high risk. In our experience, the long-term results are satisfying. After failed reconstructive surgery, or as a primary procedure, we prefer mechanical prostheses. They are well tolerated and the incidence of anticoagulation-related complications is low.

Chi-Square Distribution↗
PubMed2005

Video and robotic-assisted minimally invasive mitral valve surgery: a comparison of the Port-Access and transthoracic clamp techniques.

BACKGROUND: In order to assess different surgical techniques for video-assisted minimally invasive mitral valve surgery, a retrospective study was undertaken comparing the Port-Access system (Cardiovations, Ethicon Inc, Somerville, NJ) and the transthoracic clamp technique. METHODS: In 120 patients mitral valve surgery was performed through a small right minithoracotomy using either the Port-Access endovascular cardiopulmonary bypass system (Port-Access, n = 60) or the transthoracic clamp technique (MICRO, n = 60). Mean patient age was 61.5 +/- 10.5 years (81 patients with isolated mitral valve insufficiency, 39 patients with combined mitral valve disease). RESULTS: Eighty-one (67.5%) patients underwent mitral valve repair and 39 (32.5%) patients had valve replacement. Mean time of surgery was 4.5 +/- 3.5 and 4.1 +/- 3.2 hours (p = 0.07), aortic cross-clamp time 89 +/- 69 and 78 +/- 65 minutes (p = 0.08), mean intensive care unit stay 1.5 +/- 2.1 and 1.6 +/- 2.5 days (p = ns), and hospital stay 9.0 +/- 10.5 and 9.2 +/- 9.7 days (p = ns) in the Port-Access and MICRO groups, respectively. In the Port-Access group, there were 6 reexplorations for bleeding, one perforation of the right ventricle with the endopulmonary vent, and 2 reconstructions of the femoral artery necessary after femoral cannulation, compared to one reexploration for bleeding in the MICRO group. There was only one minor paravalvular leak after replacement and 2 cases of residual greater than or equal to grade II mitral valve regurgitation after mitral valve repair in the Port-Access group, necessitating reoperation. In both groups, there was no mortality, no cerebrovascular accident, no aortic dissection, and no conversion to sternotomy. CONCLUSIONS: Minimally invasive mitral valve surgery has become a standard approach for isolated mitral valve operations at our institution. The MICRO technique tends to shorten the time of surgery and aortic cross-clamping and reduces perioperative costs by simplifying the operative procedure.

Cardiopulmonary Bypass↗
PubMed2001

[Blood vessels in normal and abnormal mitral valve leaflets].

UNLABELLED: The incidence and the distribution of blood vessels were examined in normal and abnormal mitral valve leaflets. MATERIALS AND METHODS: Normal valves were obtained from 12 autopsy cases without cardiovascular disease (8 men, 4 women, 33 to 93 years of age). Twenty-one abnormal valves were obtained at the time of mitral valve replacement (12 men, 9 women, 16 to 78 years of age). Clinical and pathological diagnoses were rheumatic valvular disease (RVD: n=8), floppy mitral valve (FMV: n=9), and healed infective endocarditis (HIE: n=4, 1 with RVD, 3 with FMV). The number of vessels was counted at the surgical excision line of the valvular rings by immunohistochemical study using Factor VIII related antigen and CD34. Histologic studies were also made at the 5 mm distal line from the ring in normal valves, and at the vertical line to the ring in abnormal valves. RESULTS: In normal valves, the number of vessels at the ring area, except in myocardial tissues that extended from the left atrium to the auricularis, ranged from 3 to 184. Vessels were also found at the 5 mm distal area from the ring in 6 valves out of 12. Vessels were mainly distributed near the commissure areas of the auricularis and/or the spongiosa and were extended with myocardial tissues. There was no difference in the number of vessels related to age or sex. In RVD, the number of vessels at the ring area ranged from 22 to 517 in 8 anterior leaflets (AML) and 2 to 151 in 5 posterior leaflets (PML). Many vessels also appeared in the distal spongiosa of the leaflets, and arterioles were frequently found in these areas. In FMV, a few (3 and 6) vessels were found in 2 leaflets (AML: 2/8, PML: 0/4). In HIE, the number of vessels was 216 in the case with RVD, and 3 to 110 in cases with FMV. CONCLUSION: At the ring area, normal mitral valve leaflets were supplied with nutrition from blood vessels that mainly extended from the left atrium with myocardial tissues. In RVD, the vessels branched from previously existing capillaries, extending to the distal area, and increased in number. Mechanical stress during opening and closing of the leaflets contributes to the arterialization of these vessels. In FMV, the number of capillaries, which is smaller than in normal valves, might be related to the progression of this disorder. In HIE with valvular disease, the number of vessels is related to the preexisting disease.

Adult↗
PubMed2002

Results of surgery for irreversible moderate to severe mitral valve regurgitation secondary to myocardial infarction.

OBJECTIVE: Moderate to severe irreversible mitral regurgitation secondary to myocardial infarction is an independent risk factor for reduced long-term survival. Late effects of correction of mitral incompetence concomitant with coronary artery bypass grafting (CABG) are less well known and the choice of mitral valve procedure is still debated. METHODS: From 1988 to 1998, 93 consecutive patients (mean age 63+/-9 years) were treated for moderate to severe irreversible mitral regurgitation secondary to myocardial infarction; 84 were in NYHA functional class III-IV and 19 were in cardiogenic shock. Thirty-seven patients underwent emergency surgery. Perioperative intraaortic balloon pump (IABP) was necessary in 33 patients. Follow-up ranged from 6 months to 12 years (mean 51 months+/-41). RESULTS: Mitral valve was repaired in 30 patients and replaced in 63. Replacement was preferably performed in patients with major displacement of papillary muscle and in patients with acute papillary muscle rupture. CABG (3.4 distal anastomoses) was performed in all patients and was complete in 92%. Early mortality was 15% (14/93). Multivariable analysis identified need for IABP (P=0.005) and COPD (P=0.02) as risk factors for early death. Emergency surgery had only a trend (P=0.15) for increased mortality; age, low ejection fraction, repair vs. replacement had no influence. Actuarial survival rates at 1, 5 and 10 years were 81, 65 and 56%, respectively. Late survival was similar in patients with replacement or repair (P=0.46). At last follow-up, all but one patient were in NYHA functional class I or II. CONCLUSIONS: Combined mitral valve procedure and myocardial revascularization, as complete as possible, for moderate to severe mitral regurgitation secondary to myocardial infarction achieve satisfactory early and late outcome despite the increased operative mortality. Acute papillary muscle rupture, severe restriction of the mitral valve by major displacement of the papillary muscle are better managed by valve replacement.

Adult↗
PubMedDate not supplied

Mitral valve prolapse in persons with Down syndrome.

This study was designed to determine the prevalence of mitral valve prolapse and aortic insufficiency in home-reared, young persons with Down syndrome. Of the 36 individuals (ages 20-32 years) enrolled in this study, 20 had abnormal echocardiographic findings. Thirteen patients had mitral valve prolapse, 3 had both mitral valve prolapse and aortic insufficiency, 2 had only aortic insufficiency, and 2 had other mitral valve disorders. In 14 of the 16 patients with mitral valve prolapse, a midsystolic click was heard. Theories of the pathogenesis and possible complications of mitral valve prolapse and its relationship to exercise and sport activities are discussed.

Adult↗
PubMed1987

Mitral valve prolapse and thyroid abnormalities in patients with panic attacks.

Panic disorder has been associated with mitral valve prolapse and thyroid abnormalities. Mitral valve prolapse has also been associated with thyroid abnormalities. The authors studied a consecutive series of 65 patients self-referred for evaluation of panic attacks, who were examined for cardiac and thyroid abnormalities. Fifty percent of the patients had mitral valve prolapse according to both cardiac auscultation and echocardiography. Twenty-six percent of the women had some thyroid abnormality; 17% had thyroid microsomal antibodies. There was no apparent relationship between mitral valve prolapse and thyroid abnormalities. These observations suggest that panic attacks, mitral valve prolapse, and autoimmune thyroid disorders are associated.

Adult↗
PubMed1995

Predisposing factors for severe mitral regurgitation in idiopathic mitral valve prolapse.

To elucidate predisposing factors for severe mitral regurgitation (MR) in idiopathic mitral valve prolapse (MVP), 124 MVP patients were classified into the following categories: 55 with isolated clicks (click group), 35 with a late-systolic murmur (late-SM group), and 34 with a holosystolic murmur (holo-SM group). Their clinical and echocardiographic findings were compared with those of 26 patients with spontaneous chordal rupture (rupture group). In 22 patients in the click group, 24 in the late-SM group, and 22 in the holo-SM group, follow-up studies were performed for a mean of 4.5 years (range 1 to 13.5). The mean age was youngest in the click group and oldest in the rupture group. The click and late-SM groups showed a female predominance, but the holo-SM and rupture groups showed a male predominance. There was no difference in the incidence of systemic hypertension among the 4 groups. Most patients in the click and late-SM groups had anterior leaflet prolapse. In the holo-SM and rupture groups, however, the incidence of posterior leaflet involvement was significantly increased. The incidence of thickened mitral valve increased in order of the click (8%), late-SM (21%), holo-SM (38%), and rupture (50%) groups. Six patients in the holo-SM group developed chordal rupture with severe MR during the follow-up period. In the click and late-SM groups, however, there were no complications and no development into a holo-SM. Thus, aging, male sex, posterior leaflet prolapse, thickened mitral valve, and holo-SM were found to be important predisposing factors for severe MR in idiopathic MVP.

Adult↗
PubMed1992

Estimation of mitral valve area from regression analysis of the pressure gradient in mitral stenosis.

Estimation of mitral valve area (MVA) in the cardiac catheterization laboratory is prone to pitfalls because of the time required for calculations and inaccuracies in the measurement of cardiac output. Because the rate of decrease in the mitral gradient directly correlates with the severity of mitral stenosis, an on-line estimate of MVA at the time of catheterization may be possible with regression analysis of digitized pressure recordings. A total of 61 comparisons of mitral gradient measurements and MVA were obtained in 37 patients at diagnostic catheterization and in 24 patients after balloon mitral valvotomy. Linear and nonlinear regression parameters yielded pressure half-time values and empiric constants similar to those used in Doppler echocardiography for estimation of MVA. The correlations derived from linear analysis were as good as those obtained from nonlinear analysis: from linear analysis, MVAregression = 0.79.MVAGorlin -0.03; r2 = 0.64, p = 0.0001; and from double exponential analysis, MVAregression = 0.86.MVAGorlin -0.07; r2 = 0.74; p = 0.0001. The correlations were not significantly affected by the presence of mild to moderate mitral regurgitation or whether they were obtained after balloon valvotomy. In summary, linear regression analysis yields accurate estimates of MVA despite the theoretical superiority of nonlinear methods. On-line digital analysis of mitral gradient tracings may thus be useful at the time of diagnostic cardiac catheterization or balloon mitral valvotomy to assess the severity of mitral stenosis and the response to interventions.

Aged↗
PubMed1985

Mitral valve prolapse in hyperthyroidism of two different origins.

The prevalence of mitral valve prolapse was investigated in 126 patients with hyperthyroidism due to Graves' disease or toxic nodular goitre and that of hyperthyroidism in 64 patients with mitral valve prolapse. One hundred and eleven asymptomatic healthy subjects comprised a control group. The patients with hyperthyroidism were divided into those with Graves' disease and those with toxic nodular goitre. Of the group as whole, 12 (9.5%) patients had mitral valve prolapse compared with six (5.4%) in the control group, but the difference was not statistically significant. The prevalence of mitral valve prolapse in the patients with toxic goitre was also not significantly different from that in the controls. When the prevalence in the group with Graves' disease was compared with that in the control group (16.3% vs 5.4%) the difference was significant. Only one patient with mitral valve prolapse had hyperthyroidism.

Adult↗
PubMed1980

Assessment of left ventricular function during angina pectoris from the mitral valve echogram.

The echocardiographic motion pattern of the anterior mitral valve (aMV) has been shown to be related to left ventricular function. In an attempt to quantify the changes of aMV motion in patients during myocardial ischemia, the following motion phases of the aMV echo were determined in 12 patients with coronary artery disease: DE slope, EF slope, the closure slope of the aMV, as determined by joining points B and C (or in the absence of a clearly definable B point the AC slope), and the systolic motion pattern. Following coronary angiography, measurements of the aMV echo were performed in the resting state and during angina pectoris immediately after rapid atrial pacing at comparable heart rates. DE slope and EF slope showed only minor and insignificant changes during angina in the post-pacing period. The aMV closing velocity (BC or AC slope) was significantly reduced from 225.9 +/- 56 mm/sec during the control period to 177.9 +/- 43 mm/sec during angina (p < 0.01). After recovery from anginal pain measurements of the final closing velocity revealed a return to the control values with an average slope of 240.4 +/- 40 mm/sec. In 3 of 12 patients there was evidence of systolic mitral valve prolapse during the post-pacing anginal episode. Our results suggest that final mitral valve closing velocity reflects changes in left ventricular function during myocardial ischemia in the early isovolumetric phase of ventricular systole. In some patients mitral valve prolapse during angina may indicate ischemic dysfunction of the papillary muscles during the ejection of phase of systole.

Adult↗
PubMed1993

Morphological determinants of echocardiographic patterns of mitral valve systolic anterior motion in obstructive hypertrophic cardiomyopathy.

BACKGROUND: The morphological determinants of mitral valve systolic anterior motion (SAM) and obstruction to left ventricular outflow in patients within the broad clinical spectrum of hypertrophic cardiomyopathy (HCM) are not completely understood, particularly the contribution of mitral leaflet length and size. METHODS AND RESULTS: To clarify this issue, mitral valve specimens from 43 patients with HCM and basal outflow obstruction were used to relate morphometric measurements of leaflet area to certain morphological and functional assessments of left ventricular outflow tract geometry and valvular motion obtained from echocardiograms in the same patients. Twenty-four patients (56%) had mitral valves of normal size (leaflet area < 12.0 cm2) and 19 patients (44%) had enlarged and elongated valves (area > or = 12.0 cm2). Compared with normal-sized mitral valves, the enlarged valves were situated more posteriorly in a larger left ventricular outflow tract (cross-sectional area, 3.3 +/- 1.0 versus 1.9 +/- 0.7 cm2 for normal-sized valves; p < 0.001) and also had greater systolic excursion of the anterior leaflet (16.2 +/- 4.5 versus 13.3 +/- 3.3 mm, p < 0.02), usually with a distinctive sharp-angled bend and localized contact of the leaflet tip with ventricular septum ("typical" SAM); this pattern of SAM was possible because the central and distal portions of the leaflet were relatively free of fibrous thickening. In contrast, normal-sized mitral valves were situated more anteriorally in a smaller left ventricular outflow tract and frequently showed a different mechanism of SAM and subaortic obstruction with relatively limited leaflet motion, absence of a sharp bend, and septal contact involving more substantial portions of the anterior leaflet and contiguous chordae ("atypical" SAM); mitral-septal apposition was effected in large measure by posterior ventricular septal motion. This pattern of SAM was invariably associated with a more diffuse pattern of fibrous thickening. CONCLUSIONS: Patients with obstructive HCM show patterns of mitral valve SAM that are diverse and determined largely by the interrelation of left ventricular outflow tract geometry, the size and mobility of the mitral leaflets, and the presence and distribution of fibrous thickening.

Adolescent↗
PubMed1976

Mitral valve prolapse. Two-dimensional echocardiographic and angiographic correlation.

In order to define baseline descriptive criteria for the diagnosis of mitral valve prolapse with cross-sectional echocardiography, 49 patients undergoing catheterization were examined by a real-time, two-dimensional phased array echocardiographic imaging system. Angiography was used to separate patients into two distinct groups: 15 with normal mitral valve function and 34 with definite mitral valve prolapse. Systolic mitral leaflet and annulus motion were then observed in each patient and similarities and differences were noted between the two groups of patients. Correlative M-mode echocardiographic data were available in 37 patients. Certain two-dimensional echocardiographic findings restricted to the angiographically proven mitral valve prolapse group were defined: 1) posteriorly displaced coaptation of the leaflets, 2) systolic superior movement of one or both mitral leaflets above the level of the mitral ring, and 3) a systolic curling motion of the posterior mitral ring on its adjacent myocardium. One or more of these abnormalities were found in all 34 patients with angiographic mitral valve prolapse. When mitral valve prolapse does occur, the results of two-dimensional echocardiography would suggest that both leaflets are usually involved.

Adult↗
PubMed1983

Surgery in severe rheumatic mitral valve disease--recognition of severity and risk factors.

The postoperative course of 294 patients with rheumatic mitral valve disease, who underwent mitral valve surgery during a period from July, 1978 to June, 1981, was studied by comparing the influences of the following clinical parameters: a low left ventricular ejection fraction (LVEF), a high pulmonary arterial systolic pressure (PASP), a high pulmonary vascular resistance (PVR), tricuspid regurgitation (TR), a high right ventricular end-diastolic pressure (RVEDP) and a giant left atrium (GLA). The patients with a functional capacity of class III or IV according to the New York Heart Association were classified into 3 groups (improved, unimproved and died), and from this data we calculated the improvement ratio and the mortality rate. The improvement ratios were 73% in patients with a low LVEF, 70% with a high PASP, 78% with a high PVR, 66% with TR, 11% with a high RVEDP and 77% with a GLA; the mortality rates were 19, 14, 17, 24, 78 and 19%, respectively. As compared with the case of deteriorated left ventricular performance and pulmonary hypertension, deteriorated right ventricular performance, especially high RVEDP, was accompanied by a comparatively poorer surgical prognosis. It is concluded that mitral valve surgery should be performed during the period in which the right ventricular function is still preserved.

Adolescent↗