Mitral Valve Prolapse: A Disease in Search of, or Created by, Its Definition

Marfan syndrome and mitral valve prolapse

Mitral valve prolapse (MVP), an abnormal displacement into the left atrium of a thickened and redundant mitral valve during systole, is a relatively frequent abnormality in humans and may be associated with serious complications. A recent study implicates fibrillin-1, a component of extracellular matrix microfibrils, in the pathogenesis of a murine model of MVP. This investigation represents an initial step toward understanding the mechanisms involved in human MVP disease and the development of potential treatments.

Cardiac evaluation of the patient with stroke

Coronary artery disease and ischemic cerebrovascular disease are leading causes of morbidity and mortality in the United States. Coronary artery disease often coexists with asymptomatic carotid artery atherosclerosis, transient ischemic attacks, or ischemic stroke. Numerous studies have shown that mortality from all forms of ischemic cerebrovascular disease is primarily due to coronary artery disease. Thus, there is increasing interest in identifying coronary artery disease in patients with cerebrovascular disease, including those without clinical manifestations of heart disease. We review the use of current noninvasive techniques to detect coronary artery disease and present practical approaches to screen for ischemic heart disease. Current diagnostic imaging methods for potential cardioembolic sources of cerebral infarction are also discussed.

Three-dimensional echocardiographic reconstruction of the mitral valve, with implications for the diagnosis of mitral valve prolapse

Mitral valve prolapse has been diagnosed by two-dimensional echocardiographic criteria with surprising frequency in the general population, even when preselected normal subjects are examined. In most of these individuals, however, prolapse appears in the apical four-chamber view and is absent in roughly orthogonal long-axis views. Previous studies of in vitro models with nonplanar rings have shown that systolic mitral annular nonplanarity can potentially produce this discrepancy. However, to prove directly that apparent leaflet displacement in a two-dimensional view does not constitute true displacement above the three-dimensional annulus requires reconstruction of the entire mitral valve, including leaflets and annulus. Such reconstruction would also be necessary to explore the complex geometry of the valve and to derive volumetric measures of superior leaflet displacement. A technique was therefore developed and validated in vitro for three-dimensional reconstruction of the entire mitral valve. In this technique, simultaneous real-time acquisition of images and their spatial locations permits reconstruction of a localized structure by minimizing the effects of patient motion and respiration. By applying this method to 15 normal subjects, a coherent mitral valve surface could be reconstructed from intersecting scans. The results confirm mitral annular nonplanarity in systole, with a maximum deviation of 1.4 +/- 0.3 cm from planarity. They directly show that leaflets can appear to ascend above the mitral annulus in the apical four-chamber view, as they did in at least one view in all subjects, without actual leaflet displacement above the entire mitral valve in three dimensions, thereby challenging the diagnosis of prolapse by isolated four-chamber view displacement in otherwise normal individuals. This technique allows us to address a uniquely three-dimensional problem with high resolution and provide new information previously unavailable from the two-dimensional images. This new appreciation should enhance our ability to ask appropriate clinical questions relating mitral valve shape and leaflet displacement to clinical and pathologic consequences.

Diagnostic reliability of M-mode echocardiography for detecting mitral valve prolapse in 50 consecutive panic patients

Fifty consecutive panic patients had M-mode echocardiographs read independently by two cardiologists with expertise in echocardiography. In this prospective study, there was poor interrater reliability (22 of 50; K = 0.11) for diagnosis of mitral valve prolapse (MVP). On repeat evaluation 10 months later there was also unacceptable intrarater reliability for each reader: 22 of 35 (K = 0.41) and 22 of 35 (K = 0.45). We conclude that M-mode echocardiography is clinically unreliable for establishing the diagnosis of mitral valve prolapse. These findings suggest that the variable reporting of M-mode-determined mitral valve prolapse in psychiatric populations may reflect differences among echocardiologists rather than differences in cardiac pathology. The clinical implications of these findings are discussed.

Identification of high-risk and low-risk subgroups of patients with mitral-valve prolapse

Mitral-valve prolapse is a common cardiac valvular disorder with a wide range of severity and diverse clinical outcomes. The lack of a standard definition of mitral-valve prolapse may explain the variation in reported complication rates. To identify high-risk and low-risk subgroups, we retrospectively analyzed clinical and two-dimensional echocardiographic data from 456 patients with mitral-valve prolapse. Mitral-valve prolapse was defined on the basis of echocardiographic findings as systolic displacement into the left atrium of one or both leaflets beyond the plane of the mitral annulus in the parasternal long-axis view. Two groups of patients were compared: those with thickening of the mitral-valve leaflets and redundancy (designated the classic form; n = 319) and those without leaflet thickening (designated the nonclassic form; n = 137). The two groups were similar in age and sex ratio. Complications or a history of complications was more prevalent in the classic than the nonclassic form: infective endocarditis, 3.5 percent and 0 percent, respectively (P less than 0.02); moderate-to-severe mitral regurgitation, 12 percent and 0 percent (P less than 0.001); and the need for mitral-valve replacement, 6.6 percent and 0.7 percent (P less than 0.02). However, the frequency of stroke was similar in the two groups: 7.5 percent and 5.8 percent (P not significant). We conclude that in a selected population of patients with mitral-valve prolapse, those with the classic form (leaflet thickening and redundancy) are at higher risk than those without these features for the infectious and hemodynamic complications of mitral-valve prolapse, but not for stroke.

Etiology, prognosis, and hemostatic function after cerebral infarction in young adults

We retrospectively evaluated 66 patients younger than 40 years of age who presented with acute nonhemorrhagic cerebral infarction (n = 63) or transient ischemic attacks (n = 3) to determine the possible etiology and long-term outcome at a mean follow-up interval of 3 years after initial presentation. A probable cause for the stroke was identified in 24 patients (36%); this group included one woman with a history of recurrent spontaneous abortions and a positive test for the presence of the lupus anticoagulant. We performed detailed hemostatic investigations at follow-up in 38 (90%) of the remaining 42 patients in whom the cause of the stroke was unknown or uncertain; results of the basic hemostatic screening tests (including that for fibrinogen) were uniformly normal. All 38 patients demonstrated a normal fibrinolytic response as measured by tissue plasminogen activator release to a standard venous occlusion stress test; concentration of the inhibitor of tissue plasminogen activator was not increased. No abnormalities in the concentrations of the inhibitory proteins C or S or antithrombin III were identified, and none of the 38 patients had evidence of a lupus anticoagulant. Neurologic recovery was complete or the residual disability mild in 46 of 59 (78%) patients. Overall prognosis was excellent and independent of whether a precipitating factor for the stroke could be identified.

Temporal resolution of mitral regurgitation in patients with mitral valve prolapse: a phonocardiographic and Doppler echocardiographic study

To assess the timing and duration of mitral regurgitation in mitral valve prolapse, 20 patients with a mid-systolic click or late systolic murmur, or both (Group 1) and 16 patients with a pansystolic murmur with late systolic accentuation (Group 2) were studied with phonocardiography and echocardiography including various Doppler techniques. The subjects' ages ranged from 15 to 73 years. Mitral valve prolapse with mitral regurgitation was observed in 15 of 20 patients in Group 1 and in all 16 patients in Group 2. M-mode Doppler color echocardiography demonstrated a mitral regurgitant signal throughout systole and isovolumic relaxation in all but 1 of these 31 patients regardless of the pattern of the systolic murmur. The regurgitant signal was recorded after the click in only one patient with mitral valve prolapse in Group 1. Two of the five patients in Group 1 without two-dimensional echocardiographic findings of mitral valve prolapse had the early systolic signal of mitral regurgitation. The timing and duration of the mitral regurgitant signal detected in patients in Group 1 with pulsed or continuous wave Doppler ultrasound varied with the site of the sample volume or beam direction. In the patients in Group 2, however, the signal was demonstrated throughout systole and isovolumic relaxation by both Doppler methods. Compared with M-mode Doppler color echocardiography, therefore, pulsed and continuous wave Doppler methods were less sensitive and thus inadequate to investigate the timing and duration of mitral regurgitation in mitral valve prolapse, especially in patients with a mid-systolic click or a late systolic murmur, or both, who had mild or eccentric mitral regurgitant jets.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of auscultation with two-dimensional and Doppler echocardiography in patients with suspected mitral valve prolapse

Auscultation was compared to two-dimensional echocardiography (2D echo) and Doppler ultrasonography in 140 consecutive patients referred for evaluation for suspected mitral valve prolapse (MVP) to asses the precision of the two diagnostic methods. Ninety patients (64%) had midsystolic clicks, of which 42 (47%) had MVP by echocardiography; 6 patients (4%) had MVP by 2D echo but no click on examination. In 15 (17%) of the 90 patients, a click was heard only in the standing or squatting positions and 2D echo did not detect prolapse in the supine position in 10 (67%) of the 15. With auscultation as the reference standard for MVP, 2D echo has a sensitivity of 47% and a specificity of 89%. Of the 140 patients, 51 (36%) had systolic murmurs; Doppler detected mitral and/or tricuspid regurgitation in 26 (50%). In 23 (16%) patients, there was Doppler evidence of mitral or tricuspid regurgitation even though systolic murmurs were not heard. Auscultation shows a 53% sensitivity and 73% specificity for systolic murmurs, using Doppler ultrasonography as the reference standard. Of 48 patients with MVP by 2D echo, 15 (13%) had associated mitral regurgitation by Doppler. The results indicate that 2D echo and Doppler ultrasonography should be interpreted in concert with auscultation for the diagnosis of mitral valve prolapse and for therapeutic decision making.

The medicalization of normal variants: the case of mitral valve prolapse

Mild mitral valve prolapse, hypoglycemia, irritable colon, and premenstrual syndrome are examples of anatomico-physiologic phenomena that largely overlap with normal. Such "overlap syndromes" become labeled disease entities by the medical community through a process called medicalization. This report uses mitral valve prolapse (MVP) to exemplify the effects of medicalization on patients, physicians, and society. Ascertainment bias and insufficient controlled clinical studies have led to the description of a clinical entity replete with false associations (e.g., mitral valve prolapse syndrome) and overly pessimistic prognostication (e.g., risk of sudden death or endocarditis), leading to clinical overreaction, overtreatment, and unnecessary induction of disability. Though some physical complications may be prevented by recognizing severe MVP, there is substantial risk of iatrogenic harm by attributing complex symptoms and illness behavior to mild MVP, which is probably a normal variant. A three-dimensional analysis of illness experience is presented that may be of use in conceptualizing the clinical approach to overlap syndromes such as mild MVP. Conservative criteria for the diagnosis of significant MVP have been developed at the National Institutes of Health. Treatment of patients with mild MVP must emphasize that it is a normal variant without serious consequences. Because the risks of overmedicalization are so substantial, the impact of diagnostic labels on individual patients and society must be analyzed continually.

Reconsideration of echocardiographic standards for mitral valve prolapse: lack of association between leaflet displacement isolated to the apical four chamber view and independent echocardiographic evidence of abnormality

Mitral valve prolapse by current echocardiographic criteria can be diagnosed with surprising frequency in the general population, even when preselected normal subjects are examined. In most of these individuals, however, prolapse is present in the apical four chamber view and absent in roughly perpendicular long-axis views. Previous studies have shown that systolic annular nonplanarity can cause apparent prolapse in the four chamber view without actual leaflet displacement above the most superior points of the anulus, and there is evidence for such nonplanarity in vivo. It is then reasonable to ask whether superior leaflet displacement limited to the four chamber view has any pathologic significance or complications. The purpose of this study, therefore, was to address the following hypothesis: that patients with superior leaflet displacement confined to the four chamber view have no higher frequency of associated echocardiographic abnormalities than do patients without displacement in any view. Such abnormalities, which would provide independent evidence of mitral valve pathology or dysfunction, include leaflet thickening, left atrial enlargement and mitral regurgitation. Leaflet displacement was measured in the parasternal long-axis and apical four chamber views in 312 patients who were studied retrospectively and selected for the absence of forms of heart disease other than mitral valve prolapse. Leaflet thickness and left atrial size were measured and mitral regurgitation was graded. Patients with leaflet displacement limited to the four chamber view were no more likely to have associated abnormalities than were patients without displacement in any view (0 to 2% prevalence, p greater than 0.5). In contrast, patients with leaflet displacement in the long-axis view were significantly more likely to have associated abnormalities (12 to 24%, p less than 0.005), the frequency of which increased with the extent of leaflet displacement in that view (p less than 0.0001). These results suggest that displacement limited to the apical four chamber view is, in general, a normal geometric finding unassociated with echocardiographic evidence of pathologic significance.

The relationship of mitral annular shape to the diagnosis of mitral valve prolapse

The geometric or anatomic diagnosis of mitral valve prolapse, as opposed to the pathologic diagnosis of myxomatous valve disease, is based on the relationship of the mitral leaflets to the surrounding anulus. Current echocardiographic criteria for this diagnosis include leaflet displacement above the annular hinge points in any two-dimensional view; implicit in this equivalent use of intersecting views is the assumption that the mitral anulus is a euclidean plane. Prolapse by these criteria is found in a surprisingly large proportion of the general population. In most of these individuals, however, prolapse is present in the apical four-chamber view and absent in roughly orthogonal long-axis views of the left ventricle. This frequently observed discrepancy between leaflet-annular relationships in intersecting views suggests an underlying geometric property of the mitral apparatus that would produce the appearance of prolapse in one view without actual leaflet distortion. To address this possibility, a model of the mitral valve and anulus was constructed. When the model anulus was given a nonplanar, saddle-shaped configuration, the clinical observations were reproduced: the leaflets appeared to lie above the low points of the anulus in one plane, and below its high points in a perpendicular plane. Therefore, the appearance of mitral valve prolapse can occur without actual leaflet displacement above the most superior points of the mitral anulus if the anulus is nonplanar. To determine whether this pattern is reflected in the human mitral anulus, two-dimensional echocardiographic views of the mitral apparatus were obtained by rotation about the cardiac apex in 20 patients without evident annular or rheumatic valvular disease. In all cases the mitral anulus, as reconstructed from these views, had a nonplanar systolic configuration, with high points located anteriorly and posteriorly. This is consistent with the findings of other groups in animals, and would favor the appearance of prolapse in the four-chamber view and its absence in long-axis views that are oriented anteroposteriorly. This model can therefore explain the frequently observed discrepancy between leaflet-annular relationships in roughly orthogonal views. It challenges the assumption that the mitral anulus is planar as well as the diagnosis of prolapse in many otherwise normal individuals based on that assumption.

Biological markers in panic states: lactate-induced panic and mitral valve prolapse

Anxious patients, and more specifically, patients experiencing panic attacks, are thought to have a significant biological component to their illness. This study looks at two promising biological markers associated with this patient population-mitral valve prolapse and lactate-induced panic. We present our findings, which further characterize clinical and biological aspects of these two markers.

Mitral valve abnormalities and catecholamine activity in anxious patients

We studied 38 anxiety disorder patients, 19 of whom had evidence of mitral valve abnormalities by two-dimensional echocardiography. The presence or absence of mitral valve abnormalities was not related to 3-methoxy-4-hydroxyphenylglycol/creatinine excretion, platelet and plasma monoamine oxidase-type activity, or autonomic arousal as measured by blood pressure and resting heart rate. These findings fail to support the hypothesis that mitral valve abnormalities identify a specific subpopulation of anxious patients with differences in catecholamine function.

Cardiovascular effects of polycyclic antidepressants

Every day, thousands of people in the United States receive polycyclic antidepressants (PCAs) prescribed by their primary care physicians. We have examined the cardiovascular manifestations of polycyclic antidepressants in 14 patients with primary depression receiving various antidepressant drugs for a period of six months or more. None had suffered from any systemic illness. All 14 received a commonly prescribed PCA, such as doxepin, amitriptyline, imipramine, desipramine or amoxapine, in therapeutic doses. None developed any significant adverse reaction. Left ventricular function, as determined by M-mode echocardiogram, was within normal limit in all patients. A twenty-four-hour ambulatory electrocardiogram revealed rare supraventricular ectopic beats in 8 patients and ventricular ectopic activity (Lown grade 1) in 4 patients. In 1 patient, who received additional lithium carbonate for treatment of depression, both supraventricular and ventricular ectopic activity developed on rare occasions. In 4 of the 8 patients the plasma concentration of PCA was optimal or near optimal, and in 4 of the 8 patients it was subtherapeutic (even though these 4 patients had shown clinical improvement with continued polycyclic therapy). It appears from the present data that antidepressant therapy with PCAs prescribed in therapeutic doses was well tolerated, without any significant adverse cardiovascular reaction, in otherwise healthy young patients with primary depression.

New guidelines for the clinical diagnosis of mitral valve prolapse

Because the term mitral valve prolapse has pathologic connotations, considerable effort has been expended to establish acceptable diagnostic standards, but without general agreement. This report combines information from the history, physical examination, electrocardiogram, chest x-ray and 2-dimensional echocardiogram in an effort to avoid the artifice of using the 2-dimensional echocardiogram as a categoric reference standard and to establish new clinical guidelines that distinguish pathologic mitral valve prolapse--a primary connective tissue abnormality of leaflets, chordae tendineae and anulus--from normal superior systolic displacement of mitral leaflets. The objective is to avoid implications of heart disease in healthy young persons within the gaussian distribution of normal. To this end, and with the Jones criteria as a model, major and minor criteria are proposed for the clinical diagnosis of mitral valve prolapse as a pathologic entity.

Echocardiography in mitral valve disease: a review

Echocardiographic evaluation of the mitral valve has attracted much attention and generated much discussion since its beginnings, some thirty years ago. Echocardiography affords the physician a detailed assessment of mitral valve integrity unequalled by any other non-invasive test. Aside from the normal appearance of the valve, a variety of pathological conditions have been studied in detail; mitral stenosis was the first and over the years the state-of-the-art has evolved from simply looking at the EF slope as an indicator of severity to the accurate quantification utilizing planimetry and 'pressure half-time.' Mitral regurgitation, although not as well quantified as mitral stenosis, can be detected and its etiology usually determined. Mitral valve prolapse may easily be overdiagnosed by echocardiography, however together with auscultation, ultrasound remains the best way to evaluate this common condition. Echocardiography is also invaluable in the evaluation of endocarditis and prosthetic mitral valves.