Ultrastructural changes in spontaneous rupture of mitral chordae tendineae

Shannon entropy as a reliable score to diagnose human fibroelastic degenerative mitral chords: A micro-ct ex-vivo study

This paper is aimed at identifying by means of micro-CT the microstructural differences between normal and degenerative mitral marginal chordae tendineae. The control group is composed of 21 normal chords excised from 14 normal mitral valves from heart transplant recipients. The experimental group comprises 22 degenerative fibroelastic chords obtained at surgery from 11 pathological valves after mitral repair or replacement. In the control group the superficial endothelial cells and spongiosa layer remained intact, covering the wavy core collagen. In contrast, in the experimental group the collagen fibers were arranged as straightened thick bundles in a parallel configuration. 100 cross-sections were examined by micro-CT from each chord. Each image was randomized through the K-means machine learning algorithm and then, the global and local Shannon entropies were obtained. The optimum number of clusters, K, was estimated to maximize the differences between normal and degenerative chords in global and local Shannon entropy; the p-value after a nested ANOVA test was chosen as the parameter to be minimized. Optimum results were obtained with global Shannon entropy and 2≤K≤7, providing p < 0.01; for K=3, p = 2.86·10^-3. These findings open the door to novel perioperative diagnostic methods in order to avoid or reduce postoperative mitral valve regurgitation recurrences.

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.

Characterisation of the fatigue life, dynamic creep and modes of damage accumulation within mitral valve chordae tendineae

Mitral valve prolapse is often caused by either elongated or ruptured chordae tendineae (CT). In many cases, rupture is spontaneous, meaning there is no underlying cause. We hypothesised that spontaneous rupture may be due to mechanical fatigue. To investigate this hypothesis, we tested porcine marginal CT: in uniaxial tension, and in fatigue at a range of peak stresses (n=12 at 15, 10 and 7.5MPa respectively, n=6 at 5MPa). The rupture surfaces of failed CT were observed histologically, under polarised light microscopy, and SEM. The cycles to failure for 15, 10, 7.5 and 5 MPa peak stresses were: (average±SD): 5077±4366, 49513±56414, 99927±108908, 197099±69103. A Weibull plot was constructed and from this, the number of cycles at 50% probability of failure was established in order to approximate the fatigue life, which was found to be 2.43MPa at 10 million cycles. The rate of creep increases exponentially with increasing peak stress. Under histological examination it was observed that CT which have been fatigued at low stress partially lose their organised collagen structure and can sustain micro-cracks that can be linked to increases in the creep rate. Furthermore our SEM images closely matched descriptions from the literature of spontaneous in vivo rupture. In conclusion, we believe that the mechanical test results we present strongly suggest that spontaneous chordal rupture and chordal elongation in vivo can be caused by mechanical fatigue.

Clinical and pathological features of degenerative mitral valve disease: billowing mitral leaflet versus fibroelastic deficiency

PURPOSE

Degenerative mitral valve disease is distinguished with billowing mitral leaflet (BML) or fibroelastic deficiency (FED). The purpose of this study is to evaluate the clinical characteristics and the pathohistological differences between BML and FED.

METHODS

A total of 73 patients who diagnosed as degenerative mitral valve disease pathologically after mitral valve surgery for severe mitral regurgitation were enrolled. On the basis of echocardiographic features and gross appearances, they were classified as BML (9 cases) and FED (64 cases).

RESULTS

In the BML group, multiple segments of the leaflet showed billowing with elongated chordae. Therefore excessive valve tissue needed to be removed by multiple resection and suture. The FED patients had focal myxomatous changes with ruptured chordae, a single resection and suture was frequently employed. In pathological examination, the valve thickness of the BML was nearly twice as thick as the FED, and the mucopolysaccharide accumulation of the Spongiosa in the BML was over 50%, while 30% in the FED.

CONCLUSION

BML presents the characteristic valve thickening due to its abnormal production of mucopolysaccharide. Since excessive tissue was voluminous in the BML, high-grade plasty techniques, such as combination of multiple resection and chordal reconstruction were required.

Structural analysis of chordae tendineae in degenerative disease of the mitral valve

BACKGROUND

Degenerative disease of the mitral valve (DDMV) is always accompanied by lengthening and/or rupture of chordae tendineae. However, the mechanisms and the mode of chordal rupture remain controversial, and the pathologic anatomy of the apparently healthy chordae has mostly been overlooked. We analyze the structural aspects of both ruptured and intact chordae tendineae in DDMV.

METHODS AND RESULTS

Structural and ultrastructural microscopic analyses indicate that both the extracellular matrix and the interstitial cells are severely affected. Degenerative chordae show alterations in the synthesis and deposition of collagen and elastin, disorganization of collagen bundles and rupture of collagen fibres, accumulation of proteoglycans and of cellular and vesicular remnants, and cell transformation into a myofibroblast phenotype. Structural disruption makes the spongiosa and the dense collagenous core separate and break. Degeneration of the chordae is segmental, affecting both chordae that are clearly abnormal, and chordae that appear healthy on visual inspection.

CONCLUSIONS

Changes in both matrix synthesis and degradation disturb the ordered collagen arrangement and modify the structural and physical properties of the chordae. Progressive structural disruption of the diseased chordae is the cause of chordal rupture. Mitral surgery corrects the damage, but the underlying causes of DDMV are not corrected. Thus, progression of the disease and affectation of additional chordae may be at the basis of the late complications and the recurrent mitral regurgitation which occurs several years after surgery. Our results indicate that a more aggressive approach to surgery may be needed.

Synergistic effect of mitral expression of tissue inhibitor of metalloproteinase-2 with hypertension on the occurrence of mitral chordae tendinae rupture

OBJECTIVES

We previously found the association between mitral chordae tendinae ruptures (MCTR) and hypertension. Tissue inhibitor of metalloproteinase-2 (TIMP2), which expresses differently under pressure loads, could trigger a signal cascade instigating cardiac fibrosis, possibly predisposing to MCTR. We aimed to elucidate the relationship between the TIMP2 and hypertension and the effect they may have on the occurrence of MCTR.

METHODS

Using a cross-sectional study in a tertiary medical center in Taiwan, we enrolled 186 patients who had received mitral valve replacements and classified them into two groups: 64 (34%) with MCTR and 122 (66%) without MCTR. Expression of mitral TIMP2 was assessed on a semiquantitative scale (grade 0-3) by immunohistochemical staining using antibodies against TIMP2.

RESULTS

TIMP2 expression was significantly higher in MCTR patients (P < 0.001). Multiple logistic regression analysis showed four independent risk factors: TIMP2 [odds ratio (OR) = 1.82, 95% confidence interval (CI) = 1.18-2.81, P = 0.007], hypertension (OR = 2.40, CI = 1.08-5.34, P = 0.032), rheumatic heart disease (OR = 0.18, CI = 0.05-0.70, P = 0.014), and left ventricular end-diastolic dimension (OR = 1.10, CI = 1.05-1.15, P < 0.001). Among nonhypertensive patients, the higher expression of TIMP2 (grade 2 and 3 vs. 0 and 1) was associated with a 3.27-fold risk. However, hypertensive patients with higher TIMP2 expression had a significantly 10-fold higher risk (P < 0.001 for interaction).

CONCLUSION

Mitral TIMP2 expression is higher in patients with MCTR and there is a synergistic effect of mitral TIMP2 staining with hypertension on the occurrence of MCTR.

Ventricular fibrillation in acute mitral valve insufficiency caused by chordae tendineae rupture: report of a surgically corrected case

In this report, we present the case of a previously healthy 80-year-old woman who was referred to surgery after a cardiac arrest due to ventricular fibrillation successfully resuscitated; the following evaluation revealed acute mitral regurgitation due to chordae tendineae rupture. After mitral valve repair, a single-chamber cardioverter-defibrillator was implanted for secondary prevention of sudden cardiac death. After 16 months of follow-up, the patient is asymptomatic without any further episodes of ventricular arrhythmias reported, underlying the pivotal role of mitral valve repair in the prevention of potentially lethal ventricular arrhythmias.

Clinical characteristics of ruptured chordae tendineae in hospitalized patients: primary tear versus infective endocarditis

BACKGROUND

Several etiologies have been associated with the rupture of chordae tendineae. The leading causes are infective endocarditis, primary rupture, and the association with various connective tissue disorders.

HYPOTHESIS

In order to define the attributes of these patients, a retrospective study was conducted that investigated the medical files of hospitalized patients in the Sheba Medical Center, Tel-Hashomer, Israel.

METHODS

Twenty patients (17 men, 3 women) with ruptured chordae were detected. Primary rupture of the chordae tendineae had been diagnosed in 11 patients, while infectious endocarditis was the cause for the tear of the chordae tendineae in 9 patients. The patients who had primary rupture of the chordae were older than the patients with endocarditis (67.4 +/- 11.3 vs. 57 +/- 9.3 years, respectively, p < 0.05).

RESULTS

The posterior mitral valve cusp was more commonly involved (15 patients). Six of the patients with posterior mitral valve cusp involvement manifested atrial fibrillation. Mitral valve prolapse (MVP) was detected among seven patients, six of whom belonged to the group with infective endocarditis.

CONCLUSION

Primary tear and infective endocarditis are leading etiologies of ruptured chordae tendineae in hospitalized patients. Particularly among the patients with infective endocarditis, concomitant MVP was frequently detected. It is the authors' opinion that this coexistence implies that MVP may predispose to the rupture of chordae tendineae.

In vitro mitral chordal cutting by high intensity focused ultrasound

Mitral regurgitation, when it arises from functional restriction of mitral leaflet closure, can be relieved by surgical cutting of the mitral tendineae chordae. We hypothesized that high intensity focused ultrasound (HIFU) might be useful as a noninvasive extracorporeal technique for cutting mitral chordae. As a pilot study to test this hypothesis, we examined the in vitro feasibility of using HIFU to cut calf mitral chordae with diameters from 0.2 to 1.6 mm. Sixty-seven percent of chordae were completely cut with HIFU, operated at 4.67 MHz and 45 W acoustic power, with up to 120 pulses of 0.3-s duration at 2-s intervals. Forty-five percent were completely cut when the pulse duration was reduced to 0.2 s. The average diameter of those chordae, which were completely cut, was significantly smaller than that of incompletely cut chordae (0.59 +/- 0.30 versus 1.14 +/- 0.30 mm with a pulse duration of 0.2 s, p < 0.0001; 0.68 +/- 0.29 versus 1.32 +/- 0.20 mm with a pulse duration of 0.3 s, p < 0.0001). For each pulse duration, the number of pulses required for complete cutting exhibited a strong positive correlation with the chordae diameter. In conclusion, in vitro feasibility of mitral chordal cutting by HIFU depended on the diameter of chordae but was controllable by HIFU settings. (E-mail: abeyukio@aol.com).

Technetium 99m–Labeled Annexin V Scintigraphy of Platelet Activation in Vegetations of Experimental Endocarditis

Background— The pathophysiology of infective endocarditis involves a pathogen/host tissue interaction, leading to formation of infected thrombotic vegetations. Annexin V is a ligand of phosphatidylserines exposed by activated platelets and apoptotic cells. Because vegetations are platelet-fibrin clots in which platelet proaggregant activity is enhanced by bacterial colonization, we investigated the ability of annexin V labeled with technetium Tc 99m ( 99m Tc-ANX) to provide functional imaging of these vegetations in experimental models of infective endocarditis. This ability was assessed in rabbits and rats because of the different interest of these 2 species in preclinical analysis.

Methods and Results— Nonbacterial thrombotic endocarditis was induced with the use of a catheter left indwelling through the aortic or tricuspid valve, and animals were injected with either a bacterial inoculum or saline. Scintigraphic investigations were performed 5 days later and showed a higher 99m Tc-ANX uptake by vegetations in infected versus noninfected animals (ratio, 1.3 for in vivo acquisitions and 2 for autoradiography; P <0.0001 for all), whereas no significant uptake was present in controls. Right-sided endocarditis was associated with pulmonary uptake foci corresponding to emboli. Histological analysis of vegetations showed a specific uptake of 99m Tc-ANX at the interface between circulating blood and vegetation. In parallel, underlying myocardial tissue showed myocyte apoptosis and mucoid degeneration, without extracellular matrix degradation at this stage.

Conclusions— 99m Tc-ANX is suitable for functional imaging of platelet-fibrin vegetations in endocarditis, as well as embolic events. 99m Tc-ANX uptake reflects mainly platelet activation in the luminal layer of vegetations. This uptake is enhanced by bacterial colonization.

Rupture of chordae tendineae in patients with β-thalassemia

Cardiac disease is the primary cause of mortality in beta-thalassemia patients. Except for ventricular dysfunction and pulmonary hypertension that represent the main forms of heart disease in these patients, valvular abnormalities including valvular regurgitation, endocardial thickening and calcification and mitral valve prolapse have also been described. Here we present two patients with thalassemia major and mitral chordal rupture, a previously undescribed abnormality in this population. Pathogenesis of this finding may involve thalassemia-related pseudoxanthoma elasticum-like syndrome, a diffuse elastic tissue defect, which is observed with a notable frequency in these patients and has been associated with numerous cardiovascular complications, including valvular ones.

Immunolocalization of elastin, collagen type I and type III, fibronectin, and vitronectin in extracellular matrix components of normal and myxomatous mitral heart valve chordae tendineae

The identification, distribution, and localization of matrix proteins and the proteins associated with normal and degenerated elastic fibers and collagen fibrils of myxomatous chordae tendineae were studied with immunoelectron microscopy. Ultrathin sections of L R White-embedded tissue were processed by indirect immunogold cytochemistry using primary antibodies against human alpha elastin, collagen types I and III, fibronectin, and vitronectin. In normal chordae tendineae, alpha elastin antibody heavily labeled the elastic fibers in spongiosa and fibrosa, but microfibrils around them were not labeled. Antibodies to collagen type I, collagen type III, and fibronectin all labeled the collagen fibers and microfibrils in the spongiosa. Fibronectin antibody labeling was higher than collagen type III, whereas labeling by anticollagen type I was lower. Intense labeling by vitronectin was observed on the microfibrils in the spongiosa and on electron-dense material around elastic fibers in the spongiosa and fibrosa. In myxomatous chordae tendineae, alpha elastin antibody heavily labeled degenerated elastic fibers, previously unidentified reticulated structures, and other moderately electron-dense material, both in the spongiosa and in the fibrosa, but not the electron-dense fibrous material around them. Antibodies to collagen types I, III, and fibronectin heavy labeled electron-dense aggregates of fibrous material. Vitronectin labeling was observed on electron-dense longitudinally running microfibrils and on the electron-dense microfibrils around degenerated elastic fibers.

Ultrastructure abnormalities in proteoglycans, collagen fibrils, and elastic fibers in normal and myxomatous mitral valve chordae tendineae

Normal and myxomatous chordae tendineae were studied using light and electron microscopy, to assess the alterations in the appearance and mutual arrangement of proteoglycans, collagen fibrils, and elastic fibers. Specific staining with ruthenium red and cuprolinic blue in a critical electrolyte concentration mode were used to localize proteoglycans. Fresh tissues were fixed in glutaraldehyde containing the cationic dyes and embedded into Spurr resin. Semithin sections of LR White (London Resin Co., Basingstoke, U.K.)-embedded tissue were used for histochemistry. In normal chordae tendineae, the fibrosa comprised close-packed collagen fibrils intermixed with elastic fibers. These were surrounded by a thin layer of elastic fibers and collagen fibrils, both of which were closely associated with proteoglycans. In myxomatous chordae tendineae, alterations were observed in the connective tissue. Proteoglycans were more abundant and were distributed throughout the tissue. The outermost layer was transformed into an undifferentiated electron-dense mass surrounding the central fibrosa, which contained degraded elastic fibers and collagen fibrils. Collagen fibrils had faint banding or lacked a banding pattern altogether. Spaces between collagen fibrils were occupied by abnormal proteoglycans or proteoglycan aggregates. Elastic fibers showed varying degrees of degeneration and were occasionally replaced by electron-lucent spaces containing microfibrils. Accumulation of abnormal proteoglycan was also observed around degenerated elastic fibres and collagen fibrils.

Abnormalities in elastic fibers and other connective-tissue components of floppy mitral valve

Histologic, immunohistochemical, and ultrastructural studies were performed on 12 floppy mitral valves, 4 mitral valves showing focal myxomatous changes without prolapse, and 3 normal mitral valves. All floppy mitral valves were thickened by deposits of proteoglycans and also showed diverse structural abnormalities in collagen and elastic fibers. From these observations we conclude that (1) the structure of all major components of connective tissue in floppy mitral valves is abnormal; (2) alterations in collagen and accumulations of proteoglycans are nonspecific changes that may be caused by the abnormal mechanical forces to which floppy mitral valves are subjected because of their excessively large surface area; (3) the presence of excessive amounts of proteoglycans may interfere with the normal assembly of collagen and elastic fibers; (4) abnormalities of elastic fibers resemble those in other conditions characterized by structural dilatation or tissue expansion; and (5) alterations in elastin could result from defective formation, increased degradation, or both.

Ultrastructural quantification of collagen in human chordae tendineae

OBJECTIVE

To determine collagen fibril diameter distributions in the chordae tendineae and to see whether there are any differences between right and left sides of the human heart.

DESIGN

Collagen fibril diameters and the percentage volume occupied by collagen fibrils (as opposed to ground substance) were determined by means of a planimeter with a digitising tablet from electron micrographs printed at a magnification of 136; 000.

MATERIAL

Human chordae tendineae were obtained at postmortem examination from seven subjects aged 50-75 years.

MEASUREMENTS AND MAIN RESULTS

Histograms of collagen fibril diameter distributions showed a sharp, unimodal distribution. The mean collagen fibril diameters associated with the tricuspid and mitral valves were 41.1 nm and 40.5 nm respectively. The percentage volume occupied by collagen was about 39% for each valve. There were no significant differences for any of these values between the right and left sides of the heart.

CONCLUSIONS

The greater pressures present on the left side of the heart are not reflected in any difference in collagen fibril diameters within the chordae tendineae compared with the right side.

Surgical pathology of the mitral valve: gross and histological study of 1288 surgically excised valves

A consecutive series of 1288 mitral valves surgically excised from 1981 through 1989 were studied macroscopically and histologically. The explanted valves were affected by: chronic rheumatic disease (1179, 91.5%), floppy mitral valve (84, 6.5%), bacterial endocarditis (19, 1.5%), and post-ischemic mitral incompetence (6, 0.5%). Among 1179 post-rheumatic cases, mixed mitral stenosis and incompetence was the most frequent malfunction (747, 58%). Isolated mitral incompetence was diagnosed in 72 (6.11%) cases only, and isolated stenosis in 360 cases. In 52 valves, excised because of chronic rheumatic disease, the histology showed unexpected signs of acute rheumatism of the leaflets and the papillary muscles. In these patients clinical symptoms and blood tests were negative for rheumatic disease. Mitral incompetence, possibly due to papillary muscle dysfunction, was the prevalent lesion (61.5%). A total of 181 patients (14.05%) with pure mitral incompetence underwent surgery. In 84 patients (46.4%), the floppy mitral valve was the most frequent cause of valve dysfunction, 72 (39.8%) had rheumatic disease, 19 (10.5%) infective endocarditis, and 6 (3.4%) ischemic heart disease. In the group with floppy mitral valve, males were more prevalent than females (51:33). The mean age of the 4 patients with Marfan's syndrome and non-Marfan patients was noticeably different (17 vs 49 yr). Moreover leaflet deformation, tendinous cord elongation and annulus dilatation were the most common causes of valve incompetence. Floppy mitral valve and infective endocarditis were the cause of cordal rupture in 43.5% of the cases. This was a severe complication which always required emergency surgery.

Surgical pathology of disease of the mitral valve, with special reference to lesions promoting valvar incompetence

A consecutive series of 459 mitral valves, which had been surgically excised over a 6-year period, were evaluated by means of macroscopic and histologic study. Of the valves, 379 specimens showed evidence of rheumatic disease (82.6%), 51 were floppy (11.1%), while 29 (6.3%) belonged to a heterogeneous group. The last included cases of ischemic disease (2.4%), infective endocarditis (2.4%), congenital dysplasia (0.9%), rheumatoid arthritis (0.4%), and primary dystrophic calcification (0.2%). Eighty-seven patients had had pure mitral incompetence. Among these, floppiness of the leaflets was the major indication for valvar replacement (58.6%), followed by rheumatic disease (12.7%), ischaemic incompetence (12.7%), and infective endocarditis (11.5%). Particular attention was paid to the clinical-pathological profile of patients with floppy valves as the cause of severe incompetence. This confirmed the prevalence of male patients and the frequent incidence of complications, particularly rupture of tendinous cords (54.9%). A striking difference was also found between the mean age of those patients with and without Marfan's disease (15.3 vs. 53.9 years, P less than 0.001). Although mitral incompetence in the presence of a floppy valve could simply be due to deformity of the leaflets, elongation of the cords and dilatation of the atrioventricular junction, in over half of the cases the precipitating event leading to surgery was rupture of tendinous cords.

Floppy mitral valve chordae tendineae: histopathologic alterations

Pathologic studies of floppy or myxomatous mitral valves have focused primarily on changes in the valve cusps, with little attention given to the chordae tendineae. In a systematic study of the histopathology of floppy mitral valve chordae tendineae, 128 nonruptured chordae from 8 severely regurgitant floppy mitral valves were compared to 152 chordae from 10 normal control mitral valves and to 152 chordae from 8 control mitral valves with severe regurgitation due to ischemic heart disease. Collagen alterations were observed in 2% of normal mitral valve chordae and 3% of control regurgitant mitral valve chordae compared to 38% of floppy mitral valve chordae. Moderate or severe acid mucopolysaccharide accumulation was observed in 2% of normal mitral valve chordae and 3% of control regurgitant mitral valve chordae compared to 39% of floppy mitral valve chordae. Nonuniform histopathologic alterations, rare in normal and control regurgitant mitral valve chordae tendineae, were frequent in floppy mitral valve chordae tendineae (p less than 0.001). Histopathologic alterations provide the basis for abnormal physical properties previously demonstrated in floppy mitral valve chordae tendineae and may predispose to chordal elongation and rupture.

Quantitative structural analysis of collagen in chordae tendineae and its relation to floppy mitral valves and proteoglycan infiltration

Imbibition analysis, a polarised light microscopy technique, was used to examine the molecular organisation of collagen in normal and diseased mitral valve chordae tendineae. A single strut chorda from each of 23 valves (14 from necropsy specimens and nine from valve replacement surgery) was studied. The degree of molecular organisation of collagen in unstained 7 micron sections of the chordae was assessed by measuring the retardation of polarised light by the sample. Sections from each tendon were examined, after staining with Movat's pentachrome, for the presence of proteoglycan infiltration and classified as normal or abnormal on that basis. The imbibition analysis results were grouped accordingly. The retardation in the collagen in the seven chordae with proteoglycan infiltration was significantly lower than in the 16 normal chordae, indicating decreased molecular organisation. Five of the seven abnormal chordae with proteoglycan infiltration and decreased retardation were from patients with floppy mitral valves; the other two were from normal necropsy specimens. Although proteoglycan infiltration may not be a specific marker for floppy valve disease, its presence is associated with decreased molecular organisation of collagen in the chordae. Degradation of the ground substance bound to the collagen is the most plausible explanation for the measured optical changes.

Isolated mitral valve prolapse: chordal architecture as an anatomic basis in older patients

Ten patients with an average age of 58 years underwent valve replacement because of isolated mitral valve prolapse with severe regurgitation. None had clinical evidence of Marfan's syndrome or another systemic disease that would indicate that a primary connective tissue disorder was the cause of the prolapse. All 10 patients had a dome configuration of the posterior leaflet and one or more ruptured chordae related to it. The gross morphology of the resected specimens revealed marked deviations in chordal branching and the pattern of anchoring in each of the 10 cases, rendering the most severely affected parts of the leaflets less well supported. Similar changes occurred at sites remote from the principal abnormality. Microscopically, the dominant tissue change was myxomatous transformation within the affected leaflets and chordae with secondary changes at both atrial and ventricular surfaces. These findings could indicate that insufficient chordal support may have promoted the development of the floppy valve through a process of chronic undue and unbalanced stress on the valve tension and closure apparatus. The resultant degeneration of the connective tissues, histologically expressed as myxomatous transformation, may underlie stretching and thus redundance of the leaflets and eventually rupture of chordae. It is suggested that this sequence of events be considered as a possible pathogenetic mechanism of isolated mitral valve prolapse, particularly in the subset of aged patients.

Mitral valve prolapse and ruptured chordae tendineae

To determine the causes of ruptured chordae tendineae and a suspected etiologic role for mitral valve prolapse (MVP), the mitral valve in 25 consecutive and surgically proved cases of chordal rupture were examined. The diagnosis of MVP was made on the basis of redundancy and marked hooding of the mitral leaflets and on histologic changes. MVP was the underlying morphologic abnormality in 23 patients, only 1 of whom had infective endocarditis that was responsible for the rupture. Thus MVP was the only underlying morphologic abnormality in 22 of 25 patients (88%). Another finding in this study was the demonstration of auscultatory and angiographic or echocardiographic evidence of MVP in 4 patients, aged 4 to 11 years (mean 7), before chordal rupture; no patient had had endocarditis. The morphologic and historical evidence would indicate that MVP is probably the most common cause of so-called spontaneous chordal rupture.

Chordal rupture. I: aetiology and natural history

Between 1970 and 1981, 12% of patients undergoing mitral valve surgery were found to have chordal rupture. Spontaneous or primary rupture accounted for 74.6% of patients (primary group); in the remainder (secondary group) chordal rupture complicated chronic rheumatic valvular disease (8.9%), bacterial endocarditis on both normal (8.5%) and rheumatic valves (4.7%), ischaemic heart disease (2.3%), acute rheumatic fever (0.5%), and osteogenesis imperfecta (0.5%). Isolated posterior rupture was seen most frequently (54%), with anterior rupture in 36% and rupture of both mitral cusps in 10% of patients. A short symptomatic history of acute mitral regurgitation was rare, occurring in only 4% of patients in either the primary or secondary groups, suggesting that mitral regurgitation due to ruptured chordae is a progressive disease. In contrast to previous reports the clinical presentation did not help to differentiate the aetiology of the chordal rupture.

Conservative surgery for mitral valve disease: clinical and echocardiographic analysis of results

Eighty-five patients underwent mitral valve reconstruction by the Carpentier method from January 1976 to December 1981. Concomitant procedures were performed in 30 patients (aortic valve replacement in 23, coronary revascularisation in six, and tricuspid valve repair in seven). Before operation 76 patients (89%) were in clinical class II or III (New York Heart Association) and atrial fibrillation was present in 50. Thirty-six patients had valvular incompetence, while 26 had pure stenosis. The aetiology was rheumatic in 57 cases and dysplastic in 21. The patients were assessed for clinical improvement, durability of valve repair, thromboembolism, and survival. There was one death, an operative mortality rate of 1.2%, and 63 of 74 patients followed for one to six years were in clinical class I after operation. The actuarial survival was 92% with a 93% incidence of freedom from thromboemboli at five years. Six patients had embolic episodes, four of whom had aortic valve replacement. Three patients had a repeat operation 16-20 months later, a valve failure rate of 6.7%. Nineteen patients with ruptured chordae had postoperative echocardiographic assessment of myocardial and mitral valve functions; the peak rates of dimension changes of the left ventricular cavity (indicative of flow across the mitral valve) fell to normal in most patients, and the left ventricular end-diastolic dimensions decreased significantly from 6.4 (1.53) to 5.09 (1.31) cm (mean and SD)--p less than 0.05. Our results confirm that reconstructive mitral surgery is able to restore and maintain normal valve function in addition to providing satisfactory relief of symptoms.