Pathology of mitral valve stenosis and pure mitral regurgitation--Part II

Insights into malignant mitral valve degenerative disease from a sudden cardiac death cohort highlighting significant measurement differences from normal

AIMS

Mitral valve prolapse (MVP) is an accepted cause of sudden cardiac death (SCD) in most autopsy series. Diagnosis at autopsy relies upon subjective assessment with no established objective pathological criteria. This study set out to establish objective measurements to help pathologists dealing with SCD.

METHODS

We diagnosed 120 (1.5%) cases of MVP in 8108 cases of SCD. We measured the mitral annulus, anterior and posterior leaflets, rough zone and mitral annular disjunction (MAD) in 27 MVP cases and compared them to 54 age- and sex-matched normal mitral valves.

RESULTS

Age of death was 39 ± 16 years, with 59 females and 61 males. History of mild MV disease was present in 19 (16%). Eleven (9%) died associated with exertion. Left ventricular hypertrophy was present in nine (15%) females and 10 (16%) males. Both MV leaflets showed thickening and ballooning in all individuals. MVP showed highly significantly increased annular circumference, elongation and thickening of both leaflets as well as increased MAD (all P < 0.001). Left ventricular fibrosis was present in 108 (90%), with interstitial fibrosis in the posterolateral wall and papillary muscle in 88 (81%) and coexisting replacement fibrosis in 40 (37%).

CONCLUSION

This is the largest MVP associated with SCD series highlighting a young cohort with equal representation of males and females. There is involvement of both leaflets with significant annular dilatation, elongation and thickening of both leaflets with MAD. Left ventricular fibrosis explains arrhythmia. Our quantitative measurements should serve as a reference for pathologists assessing post-mortem hearts for MVP.

Mitral valve stenosis in the current era: a changing landscape

Mitral stenosis results from haemodynamic obstruction at the mitral valve level because of structural abnormalities of the valve apparatus, leading to increased resistance to the transmitral flow. Although rheumatic fever remains the predominant cause of mitral stenosis worldwide, other causes are increasingly relevant in the developed countries with degenerative mitral stenosis (DMS) because of mitral annulus calcification (MAC) becoming growingly prevalent in industrialized countries with higher life expectancy. Rheumatic mitral stenosis (RMS) and DMS display dramatic differences in pathophysiology, prognosis, and disease progression. Furthermore, to date, robust evidence regarding the management of DMS because of MAC is lacking. Nevertheless, new diagnostic techniques and catheter-based interventions are changing this landscape and paving the way to a significant reduction in DMS-related morbidity and mortality. Here we briefly review the current knowledge on the pathophysiology, diagnosis and treatment of DMS and RMS, underscoring the current diagnostic and therapeutic pathways, as well as persisting uncertainties and perspectives.

Computed Tomography of Cardiac Valves: Review

Valvular heart disease is a common clinical problem. Although echocardiography is the standard technique for the noninvasive evaluation of the valves, cardiac CT has evolved to become a useful tool in the evaluation of the cardiac structures as well. Importantly, CT allows for improved quantification of valvular calcification due to its superior spatial resolution. It may improve the detection of small valvular or perivalvular pathology or the characterization of valvular masses and vegetations. This review describes the assessment of normal and diseased heart valves by cardiac CT and discusses its strengths and weaknesses.

Mitral regurgitation in congenital heart defects: surgical techniques for reconstruction

Mitral valve regurgitation (MR) is an important source of morbidity and mortality worldwide. While globally the primary etiology is rheumatic, the incidence of MR appears to be increasing in the United States as well. There are multiple etiologies for MR, and the specific pathologic anatomy varies widely. Similarly, there are a multitude of options for operative repair, and recent series report very good survival rates as well as freedom from re-intervention.

Mitral regurgitation: current trends in diagnosis and management

Mitral regurgitation is the most prevalent heart valve disorder in the United States. Individuals with mitral regurgitation may be asymptomatic or may present with dyspnea, orthopnea, fatigue, and/or heart rhythm disturbances. Long-standing mitral regurgitation causes chronic left ventricular volume overload, which leads to left ventricular dilation and contractile dysfunction. Without treatment, mitral regurgitation results in biventricular failure and death. Echocardiography is the preferred diagnostic test to assess the presence and severity of mitral regurgitation. Mitral valve surgery, the only effective treatment for patients with severe mitral regurgitation, is recommended early in the course of the disease to prevent the development of heart failure. Early recognition of mitral regurgitation and timely referral for mitral valve surgery significantly improve symptoms and long-term survival.

Computed tomography evaluation of cardiac valves: a review

Electrocardiograph (ECG)-gated cardiac computed tomography (CT) angiography has great potential for the evaluation of the cardiac valves, with excellent image quality. The evidence-based, established clinical role of ECG-gated CT coronary angiography provides additional valuable information about valve morphology and function. A wide range of valve pathology, including congenital and acquired conditions, infectious endocarditis, and complications of valve replacement, can be assessed by cardiac CT imaging. Despite recent advances in CT technology, echocardiography remains the gold standard for noninvasive cardiac valve evaluation. Nevertheless, important clinical information about the valves can be obtained with coronary CT angiography examinations. Thus cardiac valve morphology and function should be routinely assessed and reported on coronary CT angiography examinations.

CT angiography of the cardiac valves: normal, diseased, and postoperative appearances

Although echocardiography remains the principal imaging technique for assessment of the cardiac valves, contrast material-enhanced electrocardiographically gated computed tomographic (CT) angiography is proving to be an increasingly valuable complementary modality in this setting. CT angiography allows excellent visualization of the morphologic features and function of the normal valves, as well as of a wide range of valve diseases, including congenital and acquired diseases, infectious endocarditis, and complications of valve replacement. The number, thickness, and opening and closing of the valve leaflets, as well as the presence of valve calcification, can be directly observed. CT angiography also permits simultaneous assessment of the valves and coronary arteries, which may prove valuable in presurgical planning. Unlike echocardiography and magnetic resonance imaging, however, CT angiography requires ionizing radiation and does not provide a direct measure of the valvular pressure gradient. Nevertheless, with further development of related imaging techniques, CT angiography can be expected to play an increasingly important role in the evaluation of the cardiac valves. Supplemental material available at http://radiographics.rsna.org/cgi/content/full/29/5/1393/DC1.

Mitral insufficiency and its different aetiologies: old and new insights for appropriate surgical indications and treatment

Mitral insufficiency, as many other fields in medicine, has witnessed profound changes in terms of knowledge, diagnostic process and therapeutic options. Mitral valve reconstruction has become the treatment of choice in the presence of a regurgitant valve, although numerous preoperative and operative clues have been shown to predict less satisfactory results of valve repair in the long term, calling for a careful revision of postoperative data and search for novel techniques of valve repair or reconsider valve replacement as an acceptable therapy in peculiar cases. Old scenarios, like rheumatic valve disease or acute endocarditis, are continuously under reassessment in an attempt to distinguish patient subsets amenable to tailored therapies, whereas new fields of intervention, like dilated cardiomyopathy, or better appraisal of pathophysiological mechanisms, like ischaemic mitral insufficiency, are emerging and represent new indications for surgical solutions. The most recent advances in the understanding of how some aetiologies and related mechanisms of mitral insufficiency exert substantial influence on the postoperative results represent new tools in the guidance of a more appropriate surgical decision-making.

Surgical pathology and etiology of 278 surgically removed mitral valves with pure regurgitation in Thailand

INTRODUCTION

There are multiple causes of mitral regurgitation. Its etiology includes floppy valve, postinflammatory disease, infective endocarditis, and other disorders. Recently, there has been an increased tendency to remove only portions of the mitral valve, causing difficulty in the determination of etiology. Our objective was to study the pathology and etiology of mitral regurgitation from surgically removed specimens.

METHODS

Native mitral valve specimens surgically excised due to mitral insufficiency were examined. Etiology was determined according to macroscopic, microscopic, clinical, and operative findings.

RESULTS

Among 278 mitral valve specimens, 43% were classified as floppy valve, 31% as postinflammatory disease (presumably associated with rheumatic fever), 12% as infective endocarditis, and 14% as miscellaneous group. In floppy valves, diffuse myxoid change and chordal rupture were the main findings. In postinflammatory disease, moderate neovascularization and chronic inflammatory cell infiltration were most commonly found. Aschoff bodies were found in two cases. In infective endocarditis, gram-positive cocci were found in 70% of cases. In the miscellaneous group, three cases were related to Marfan syndrome and one case was related to papillary muscle necrosis. In comparison with postinflammatory disease, the posterior leaflet in the floppy valve had a significantly longer basal free-edge length, a more frequent chordal rupture, and an higher mean age of patients. Among completely and partially excised specimens with postinflammatory disease, there were no significant differences in microscopic findings.

CONCLUSION

The three most common etiologies in mitral regurgitation were floppy valve, postinflammatory disease, and infective endocarditis. Macroscopic, microscopic, clinical, and operative findings are important in the evaluation of etiology, especially in partially excised specimens.

Acquired Mitral Stenosis in a Cat with Hypertrophic Cardiomyopathy

A seven-year-old castrated male domestic shorthair cat was diagnosed with hypertrophic cardiomyopathy (HCM) and suspected mitral stenosis (MS) based on electrocardiography, thoracic radiographs and echocardiographic findings. Post-mortem examination of the heart revealed morphological features consistent with HCM. In addition, there was marked fibrous deposition on the surfaces of the chordae tendineae extending to both mitral valve leaflets, which caused total chordal fusion into pillars of fibrous tissue and fusion of the commissures. The present case indicates that acquired MS can occur in association with HCM in the cat.

Morphologic features of the rheumatic mitral regurgitant valve by three-dimensional echocardiography

BACKGROUND

Rheumatic fever remains a significant worldwide cause of mitral regurgitation (MR). We describe morphologic features of the rheumatic MR valve by quantitative 3-dimensional (3D) echocardiography.

METHODS

Eight healthy subjects and 16 patients with less than moderate (n = 7) or more than or equal to moderate (n = 9) rheumatic MR underwent 3D echocardiography by use of freehand transthoracic scanning. Left ventricular (LV) borders, mitral chordae, papillary muscles and annuli were traced at end-diastole (ED) and end-systole (ES) with LV surfaces and mitral annulus reconstructed in 3D. Regional LV function was quantified by myocardial thickening. Regional LV shape was assessed by alignment of diseased ED endocardial surfaces to a reference normal surface.

RESULTS

In the diseased group, LVs were more spheric and had regional shape abnormality in the area of anterior papillary muscle attachment. LV volumes, ejection fraction, and regional function in the areas of papillary attachment were not different. Mitral annular length and area were increased and correlated with LVED volume but were no different in height, sphericity, or beat-to-beat deformity. Chordal and papillary muscle lengths were not reduced. The interchordal angle (between the anterior and posterior chordae) was more acute in MR.

CONCLUSION

Alterations in LV geometry and mitral apparatus morphologic features contribute to rheumatic regurgitant disease. Consequent changes include malalignment of the papillary muscles and a narrowed interchordal angle that is opposite to the widening seen in MR from dilated cardiomyopathy. We hypothesize that leaflet involvement with retraction causes increased tension on the chordae, a reduction in the interchordal angle, and a consequent coaptation defect.

Progress in mitral and aortic regurgitation

Over the past 15 years there has been rapid and dramatic change in the therapy for valvular heart disease. When mitral and aortic regurgitation are severe, they inevitably cause left ventricular damage, eventually resulting in death. However, when surgical correction of these lesions is timed appropriately, longevity can approach that of a normal population after surgery. As surgical techniques have improved, surgery is now indicated earlier in the course of these diseases. It is clear that some patients with mitral and aortic regurgitation require surgery even though they are entirely asymptomatic. However, it must be emphasized that mitral and aortic regurgitation are quite different from one another. These different lesions result in different loading conditions, different pathophysiologies, and have different means for surgical correction. All of these issues impact on the proper timing of surgery and are discussed.

Surgical timing for mitral valve regurgitation

Advances in diagnostic and surgical techniques in the management of mitral regurgitation have resulted in improved survival rates and clinical outcomes. Echocardiography is a valuable noninvasive diagnostic tool in the determination of the timing of surgical correction of mitral regurgitation. Improved surgical techniques, the growing role of mitral valve repair, low operative mortality rates, and improved long-term survival rates are important considerations for earlier surgical intervention in symptomatic patients and in asymptomatic patients with echocardiographic criteria of left ventricular dilatation. Intraoperative transesophageal echocardiography is very useful in mitral valve repair and valve replacement with preservation of chordal structures.

Pathology of mitral valve in regularly slaughtered pigs: an abattoir survey on the occurrence of myxoid degeneration (endocardiosis), fibrosis and valvulitis

The aim of this study was to report the prevalence of degenerative and early inflammatory lesions and to discuss some histological aspects of normal and pathological mitral valve leaflets in healthy, normally slaughtered pigs. Mitral valves were collected from 112, 6 month-old, pigs reared under different conditions. Histological examination revealed the presence of myxoid degeneration in 29.5% of the valves with no significantly different prevalence according to rearing conditions; fibrosis was present in 12.5%; inflammation (non-vegetative valvulitis) occurred in 20 (17.9%) macroscopically normal valves. No vegetative endocarditis could be observed. A significantly higher degree of inflammation was observed in valves affected by myxoid degeneration (P < 0.05) and Anitschkow cells were prevalent in all the pathological valves (P < 0.01). Capillaries were observed in a wide majority of the valves (86.5%), but small arterioles were related to fibrotic thickening of the leaflets (P < 0.01). The following conclusions are discussed: (1) environmental factors seem not to influence the prevalence of endocardiosis; (2) inflammatory foci in myxoid valves are a reaction to both abnormal friction and products of degraded collagen and extracellular matrix; (3) the authors consider the presence of capillaries in pig valves a normal finding whereas proliferation of the vessels occurs under pathological conditions; (4) non vegetative valvulitis can be related to the presence of vessels in the valve and may have a role in both infectious endocarditis and fibrosis; (5) Anitschkow cells are normally observed in pig valves and are not specifically related to pathological lesions.

Pathology of pulmonic valve stenosis and pure regurgitation

Little morphologic information is available on operatively excised pulmonic valves. The causes of pulmonic stenosis are limited to a few conditions: (1) rheumatic and (2) nonrheumatic (congenital, carcinoid, infective endocarditis). Congenital causes of pulmonic stenosis constitute well over 95% of these conditions. Congenital types of pulmonic stenosis include acommissural dome-shaped, dysplastic, and bicuspid. Rare acquired causes of pulmonic stenosis include carcinoid, rheumatic, and infective endocarditis. Of the acquired causes of pulmonic stenosis, carcinoid is the most common condition. In contrast, causes of pure pulmonic regurgitation are multiple. Two major categories of pure pulmonic regurgitation include (1) conditions associated with anatomically abnormal valve cusps (congenital, rheumatic, carcinoid, trauma, and infective endocarditis) and (2) conditions associated with anatomically normal cusps (elevated pulmonary artery systolic pressures, idiopathic dilated pulmonary trunk, and Marfan's syndrome).