Mitral valve prolapse as a risk factor for infective endocarditis

Floppy Mitral Valve/Mitral Valve Prolapse and Manifestations Not Related to Mitral Regurgitation: Time to Search the Dark Side of the Moon

BACKGROUND

Floppy mitral valve/mitral valve prolapse (FMV/MVP) is a complex entity in which several clinical manifestations are not directly related to the severity of mitral regurgitation (MR).

SUMMARY

Patients with FMV/MVP and trivial to mild MR may have exercise intolerance, orthostatic phenomena, syncope/presyncope, chest pain, and ventricular arrhythmias, among others. Several anatomical and pathophysiologic consequences related to the abnormal mitral valve apparatus and to prolapse of the mitral leaflets into the left atrium provide some explanation for these symptoms. Further, it should be emphasized that MVP is a non-specific finding, while FMV (redundant mitral leaflets, elongated/rupture chordae tendineae, annular dilatation) is the central issue in the MVP story.

KEY MESSAGE

The purpose of this review was to highlight the clinical manifestations of FMV/MVP not directly related to the severity of MR and to discuss the pathophysiologic mechanisms contributing to these manifestations.

Mitral valve prolapse and physical performance in Asian military males: The CHIEF Heart study

The impact of mitral valve prolapse (MVP) and mitral regurgitation (MR) on physical performance has not been examined. Of 1,808 physically fit Asian military males, we compared the physical fitness between 62 subjects with MVP (MVP(+)) and 1,311 age- and anthropometrics-matched controls from the 1,746 participants without MVP (MVP(-)). MVP and MR grade were defined based on the American Society of Echocardiography criteria. Aerobic endurance capacity was evaluated by a 3000-m run and muscular endurance capacity was separately evaluated by 2-min sit-ups and 2-min push-ups. Analysis of covariance was used to determine the difference between groups. As compared to the MVP(-), the MVP(+) completed the 3000-m run test faster (839.2 ± 65.3 sec vs. 866.6 ± 86.8 sec, p = 0.019), but did fewer push-ups (41.3 ± 3.92 vs. 48.0 ± 10.1, p = 0.02) and similar sit-ups within 2 min. Of the MVP(+), those with any MR (trivial, mild or moderate) completed the 3000-m run test faster than those without MR (830.6 ± 61.7 sec vs. 877.2 ± 61.7 sec, p = 0.02). Our findings suggest that in physically active Asian military males, the MVP(+) may have greater aerobic endurance capacity but lower muscular endurance capacity than the MVP(-). The presence of MR may play a role for the MVP(+) to have greater aerobic endurance capacity.

Prevalence and characteristics of mitral valve prolapse in military young adults in Taiwan of the CHIEF Heart Study

The prevalence of mitral valve prolapse (MVP) among middle- and older-aged individuals is estimated to be 2–4% in Western countries. However, few studies have been conducted among Asian individuals and young adults. This study included a sample of 2442 consecutive military adults aged 18–39 years in Hualien, Taiwan. MVP was defined as displacement of the anterior or posterior leaflet of the mitral valve to the mid portion of the annular hinge point > 2 mm in the parasternal long-axis view of echocardiography. Cardiac chamber size and wall thickness were measured based on the latest criteria of the American Society of Echocardiography. The clinical features of participants with MVP and those without MVP were compared using a two-sample t test, and the cardiac structures were compared using analysis of covariance with adjustment for body surface area (BSA). Eighty-two participants were diagnosed with MVP, and the prevalence was 3.36% in the overall population. Compared with those without MVP, participants with MVP had a lower body mass index (kg/m²) (24.89 ± 3.70 vs. 23.91 ± 3.45, p = 0.02) and higher prevalence of somatic symptoms related to exercise (11.0% vs. 4.9%, p = 0.02) and systolic click in auscultation (18.3% vs. 0.6%, p < 0.01). In addition, participants with MVP had greater left ventricular mass (gm) and smaller right ventricular wall thickness (mm) and dimensions (mm) indexed by BSA than those without MVP (149.12 ± 35.76 vs. 155.38 ± 36.26; 4.66 ± 0.63 vs. 4.40 ± 0.68; 26.57 ± 3.99 vs. 25.41 ± 4.35, respectively, all p-values < 0.01). In conclusion, the prevalence and clinical features of MVP in military young adults in Taiwan were in line with those in Western countries. Whether the novel MVP phenotype found in this study has any pathological meaning needs further investigation.

Prevalence and correlates of mitral valve prolapse in a population-based sample of American Indians: the Strong Heart Study

PURPOSE

Mitral valve prolapse is heritable and occurs frequently in the general population despite associations with mitral regurgitation and infective endocarditis, suggesting that selective advantages might be associated with mitral valve prolapse.

SUBJECTS AND METHODS

Clinical examination and 2-dimensional and color Doppler echocardiography were performed in 3340 American Indian participants in the Strong Heart Study.

RESULTS

Mitral valve prolapse (clear-cut billowing of one or both mitral leaflets across the mitral anular plane in 2-dimensional parasternal long-axis recordings or >2-mm late systolic posterior displacement of mitral leaflets by M mode) occurred in 37 (1.8%) of 2077 women and 20 (1.6%) of 1263 men (P = 0.88); 32 (3.5%) of 907 patients with normal glucose tolerance, 11 (2.3%) of 486 patients with impaired glucose tolerance, and 13 (0.7%) of 1735 patients with diabetes (P <0.0001). Participants with mitral valve prolapse had lower mean (+/- SD) body mass index (28 +/- 5 kg/m(2) vs. 31 +/- 6 kg/m(2), P = 0.001) and blood pressure (124/71 +/- 19/10 mm Hg vs. 130/75 +/- 21/10 mm Hg, P <0.05), as well as lower levels of fasting glucose, triglycerides, serum creatinine, and log urine albumin/creatinine ratio (all P <0.001), than did those without mitral valve prolapse, although all subjects were similar in age (60 +/- 8 years). Participants with mitral valve prolapse had lower ventricular septal (0.87 +/- 0.08 cm vs. 0.93 +/- 0.13 cm) and posterior wall thicknesses (0.82 +/- 0.08 cm vs. 0.87 +/- 0.10 cm), mass (38 +/- 7 g/m(2.7) vs. 42 +/- 11 g/m(2.7)), and relative wall thickness (0.33 +/- 0.04 vs. 0.35 +/- 0.05), and increased stress-corrected midwall shortening (all P <0.01). Mitral valve prolapse was associated with a higher prevalence of mild (16 of 57 [28%] vs. 614 of 3283 [19%]) and more severe mitral regurgitation (5 of 57 [9%] vs. 48 of 3283 [1%], P <0.0001). Regression analyses showed prolapse was associated with low ventricular relative wall thickness, high midwall function, and low urine albumin/creatinine ratio, independent of age, sex, body mass index, and diabetes.

CONCLUSIONS

Mitral valve prolapse is fairly common and is strongly associated with mitral regurgitation in the general population. However, it is also associated with lower body weight, blood pressure, and prevalence of diabetes; a more favorable metabolic profile and ventricular geometry; and better myocardial and renal function.

Unusual cases of endocarditis

Endocarditis is an uncommon disease, with approximately one episode per 1000 admissions. However, patients frequently have a prolonged hospital stay and may need cardiac surgery, sometimes with a diff icult postoperative course requiring intensive care. Endocarditis can mimic many other illnesses and sometimes other illnesses can present like endocarditis. onsequently, delayed diagnosis is a major factor in patients who fail treatment. Management of this disease is only likely to be successful if there is close cooperation between physician, surgeon and microbiologist.

Severe mitral regurgitation due to mitral valve prolapse: risk factors for development, progression, and need for mitral valve surgery

Patients with mitral valve prolapse (MVP) may develop severe mitral regurgitation (MR) and require valve surgery. Preliminary data suggest that high body weight and blood pressure might add to the irreversible factors of older age and male gender in increasing risk of these complications. Fifty-four patients with severe MR due to MVP were compared with 117 control subjects with uncomplicated MVP to elucidate factors independently associated with severe MR: the need for valve surgery and the cumulative risk of requiring mitral valve surgery. Patients with severe MR were older (p<0.00005), more overweight (p = 0.002), had higher systolic (p = 0.0003) and diastolic (p = 0.007) blood pressures, and were more likely to have hypertension (p = 0.0001) and to be men (p<0.001). In both groups, men had higher blood pressure and relative body weight than women. In multivariate analysis, older age was most strongly associated with MR; higher body mass index, hypertension, and gender were independent predictors of severe MR in analyses that excluded age. Among the 54 patients with severe MR, the 32 (59%) who underwent mitral valve surgery during 11 years of follow-up were older, more overweight, and more likely to be hypertensive than those not requiring surgery. Among patients undergoing mitral valve surgery in 3 centers, mitral prolapse was the etiology in 25%, 67% of whom were men. Using these data and national statistics, we estimate that the gender-specific cumulative risk for requiring valvular surgery for severe MR in subjects with MVP is 0.8% in women and 2.6% in men before age 65, and 1.4% and 5.5% by age 75. Thus, subjects with MVP who are older, more overweight, and hypertensive are at greater risk for severe MR and valve surgery. Higher blood pressure and relative weight in men with MVP appear to contribute to the gender difference in risk for severe MR.

-Curative and preventive antibiotic therapy in infective endocarditis-

Durack's criteria, including echocardiographic manifestations, are the current standard for the diagnosis of infective endocarditis (IE). The most common microorganisms known to cause IE are streptococci and staphylococci, and therapeutic principles are based on an association of parenteral antibiotics, as far as possible bactericidal and prolonged. Treatment also includes the search for the source of infection and its eradication. IE with negative blood cultures requires special techniques to obtain the causal microorganisms. In about half of the cases, a nosocomial bacteriaemia results in IE in patients with a prosthetic valve. Surgery is mandatory in IE with complications and/or caused by particular microorganisms; surgery is essential in most patients with a prosthetic valve. Although the presence of specific links between some procedures and the occurrence of IE has not been clearly proven, a prevention policy is nevertheless justified, considering the morbidity and mortality. Prophylaxis is indicated in patients with the cardiac conditions at risk for IE. IE prophylaxis prevails over prophylactic antibiotics usually administered for surgery.

Valvular heart disease in pregnancy. A contemporary perspective

Valvular heart disease may have a significant impact on the course and outcome of pregnancy with implications for fetal as well as maternal health. Optimally, serious symptomatic valvular heart disease should be detected and treated before pregnancy. Whether a pregnant woman is known to have valvular heart disease or is diagnosed during pregnancy, it is imperative that she is managed by an experienced multidisciplinary team. Although medical therapy may alleviate symptoms of heart failure in some patients, definitive intervention either with percutaneous balloon valvuloplasty or with surgical valve replacement may be necessary.

Alcohol- and Caffeine-Induced Changes in Mitral Valve Echo Morphology and Auscultation in Healthy Females

Mitral valve prolapse (MVP) is a common cardiac valve abnormality that affects women more frequently than men. We have shown that mild dehydration induces echocardiographic signs of MVP in healthy females more frequently than in males. The present study investigated whether ethanol and caffeine, two commonly used substances, will induce changes in mitral leaflet morphology in normal subjects and whether these changes are gender dependent. Ten healthy volunteers were examined after ingesting 0.95 g/kg ethanol at breath ethanol values of 0.025% +/- 0.005%, 0.050% +/- 0.005%, and 0.075% (peak) +/- 0.005%, and at decreasing ethanol levels of 0.050% +/- 0.005% and 0.025% +/- 0.005%. Twelve healthy subjects were studied at 1.5, 3, and 4.5 hours after ingesting 5 mg/kg body weight of caffeine in a randomized, double-blind, crossover manner. A significant increase in mitral valve shape index (MVSI) on apical four-chamber view was documented in females following ethanol ingestion at all ethanol levels. These changes were accompanied by auscultatory findings characteristic of MVP. Decreased systemic vascular resistance, and afterload and increased heart rate, also occurred after ethanol ingestion. A significant increase in MVSI occurred on parasternal long axis in females at peak caffeine level; auscultatory findings characteristic of MVP also were documented. MVSI increased slightly on apical four-chamber view in males; however, no male subject developed auscultatory MVP. Body mass index was significantly lower in females (20.8 +/- 0.7 kg/m(2)) versus males (23.7 +/- 0.3 kg/m(2), P < 0.05). All subjects lost weight after caffeine intake; afterload and contractility also were increased. This study documents that ethanol and caffeine, at concentrations similar to those present in social intake, induced significant echo changes in mitral leaflet morphology and auscultation suggestive of MVP in healthy females. These results suggest that in addition to apparent hydration state, recent ethanol or caffeine intake should be taken into consideration before making the diagnosis of MVP.

Prevention of bacterial endocarditis: recommendations by the American Heart Association

OBJECTIVE

To update recommendations issued by the American Heart Association last published in 1990 for the prevention of bacterial endocarditis in individuals at risk for this disease.

PARTICIPANTS

An ad hoc writing group appointed by the American Heart Association for their expertise in endocarditis and treatment with liaison members representing the American Dental Association, the infectious Diseases Society of America, the American Academy of Pediatrics and the American Society for Gastrointestinal Endoscopy.

EVIDENCE

The recommendations in this article reflect analyses of relevant literature regarding procedure-related endocarditis, in vitro susceptibility data of pathogens causing endocarditis, results of prophylactic studies in animal models of endocarditis and retrospective analyses of human endocarditis cases in terms of antibiotic prophylaxis usage patterns and apparent prophylaxis failures. MEDLINE database searches from 1936 through 1996 were done using root words endocarditis, bacteremia and antibiotic prophylaxis. Recommendations in this document fall into evidence level III of the U.S. Preventive Services Task Force categories of evidence.

CONSENSUS PROCESS

The recommendations were formulated by the writing group after specific therapeutic regimens were discussed. The consensus statement was subsequently reviewed by outside experts not affiliated with the writing group and by the Science Advisory and Coordinating Committee of the American Heart Association. These guidelines are meant to aid practitioners but are not intended as the standard of care or as a substitute for clinical judgment.

CONCLUSIONS

Major changes in the updated recommendations include the following: (1) emphasis that most cases of endocarditis are not attributable to an invasive procedure; (2) cardiac conditions are stratified into high-, moderate- and negligible-risk categories based on potential outcome if endocarditis develops; (3) procedures that may cause bacteremia and for which prophylaxis is recommended are more clearly specified; (4) an algorithm was developed to more clearly define when prophylaxis is recommended for patients with mitral valve prolapse; (5) for oral or dental procedures the initial amoxicillin dose is reduced to 2 g, a follow-up antibiotic dose is no longer recommended, erythromycin is no longer recommended for penicillin-allergic individuals, but clindamycin and other alternatives are offered.

Risks for and prevention of infective endocarditis

It is accepted medical practice to prevent bacterial endocarditis in patients with susceptible congenital or acquired cardiac malformations who are likely to experience predictable procedure-related bacteremia. Patients in general, those with congenital heart disease specifically, are insufficiently aware of the need for such prophylaxis. It is responsibility of the physician to determine which patients are susceptible to endocarditis and the need for endocarditis prophylaxis for each patient for any given instance and to educate the patient as to this need. The American Heart Association provides wallet-sized cards that may be given to each patient. Those patients not previously known to have heart disease are, of course, not eligible for chemoprophylaxis. Because these represent many of the patients with endocarditis each year, it can be argued that only a minority of patients have preventable cases. Regarding the clinical application of anti-infective endocarditis prophylaxis, the American Heart Association gives this perspective: This statement represents recommended guidelines to supplement practitioners in the exercise of their clinical judgement and is not intended as a standard of care for all cases.... Because no adequate, controlled clinical trials of antibiotic regimens for the prevention of bacteria endocarditis in humans have been done, recommendations are based on vitro studies, clinical experience, data from experimental animal models, and assessment of both the bacteria most likely to produce bacteremia from a given site and those most likely to result in endocarditis. Bacterial endocarditis is one of the few infectious disease that almost always result in death unless treated. The dramatic nature of the morbidity and mortality of infective endocarditis in those so afflicted makes the prevention of even a few cases worth the effort.

Gender differences in dehydration-induced mitral valve prolapse

Mitral valve prolapse (MVP) is a common cardiac valve abnormality that affects women more frequently than men. We have previously shown that mild dehydration induces echocardiographic signs of MVP in approximately 50% of healthy asthenic women with previously normal cardiac findings. The present study was designed to investigate whether dehydration can induce MVP in normal men. Ten healthy male volunteers with a mean body mass index of 24.2 kg/m2, unremarkable history, and normal cardiac findings and echocardiogram were examined after mild diuresis with 20 mg furosemide. Significant decrease in weight, left ventricular end-diastolic dimension, and cardiac output were detected in all subjects after furosemide administration. In 1 (10%) of the 10 subjects echocardiographic MVP developed after furosemide administration. All furosemide-induced changes resolved with hydration. These results demonstrate that dehydration-induced MVP in men without characteristic body habitus of MVP occurs with substantially lower frequency than previously documented in women with the characteristic body habitus of MVP. This study suggests the importance of gender and body habitus in dehydration-induced MVP.

Cost-effectiveness of infective endocarditis prophylaxis for mitral valve prolapse with or without a mitral regurgitant murmur

To assess the cost-effectiveness of prevention of infective endocarditis (IE) and to calculate cost-effectiveness of currently recommended regimens in patients with mitral valve prolapse (MVP), data on risk of death, complications, and health-care use, and cumulative incremental health-care costs due to the occurrence of IE were combined with data on the prevalence and manifestations of MVP, estimated years of life lost, and efficacy of antibiotic prophylaxis. Effectiveness and costs of standard endocarditis prophylaxis regimens were calculated per IE case prevented and years of life saved. Under the most likely scenario, oral amoxicillin prophylaxis for all MVP patients would prevent 32 cases of IE per million dental procedures at approximate costs of $119,000 per prevented case and $21,000 per year of life saved. Limiting prophylaxis to patients with mitral murmurs would prevent 80 cases of IE per million procedures at costs of about $19,000 per prevented case and $3,000 per year of life saved. Erythromycin prophylaxis was slightly less expensive than amoxicillin per benefit because of lower cost and lack of drug anaphylaxis, whereas intravenous ampicillin was 7 to 30 times more costly. Sensitivity analyses suggested that erythromycin prophylaxis might be cost-saving under some scenarios, whereas intravenous ampicillin use might cause net loss of life. Thus, prevention with oral antibiotics of the cumulative morbidity and incremental health care costs due to IE in MVP patients is reasonably cost-effective for MVP patients with mitral murmurs.

Infective endocarditis and the dental practitioner

This article reviews the relationship of dental treatment to infective endocarditis (IE). The current guidelines on the use of antibiotics in prophylaxis are also examined.

In vivo mitral valve morphology and motion in mitral valve prolapse

Mitral leaflet morphology in mitral valve prolapse (MVP) has been suggested to be prognostically important, but in vivo valvular morphology is incompletely described in patients with MVP or in normal subjects. Accordingly, the length of both mitral leaflets and their zone of apposition, the thickness of their rough and clear zones, diastolic and systolic mitral annular diameters, and indexes of abnormal leaflet motion were measured in the parasternal long-axis echocardiographic view in 100 patients with MVP and 100 age- and sex-matched normal subjects. In both groups posterior leaflet thickness was related to age, as were anterior leaflet thickness and posterior leaflet length in patients with MVP. Compared with normal subjects, MVP patients without mitral regurgitation had thickened leaflets, elongated anterior leaflets, and large annular diameters (p < 0.0001). Patients with severe regurgitation had thicker leaflets, longer posterior leaflet and annular dimensions, and more abnormal leaflet motion than MVP patients without regurgitation. Leaflet thicknesses of different zones were supranormal in 60% to 67% and in 49% to 59% of MVP patients with and without severe regurgitation, respectively. MVP patients with regurgitation also had higher prevalences of abnormal mitral annular diameter than those without regurgitation (67% vs 29%) and > 3 mm posterior leaflet billowing into the left atrium (60% vs 34%). Thus, mitral valve size and leaflet thickness are increased in MVP patients without as well as with clinically important mitral regurgitation. The usefulness of leaflet thickening as a marker of severe MVP is limited by its high prevalence in patients with clinically mild MVP.

Clinical and health care cost consequences of infective endocarditis in mitral valve prolapse

Although mitral valve prolapse (MVP) predisposes to infective endocarditis (IE), both the clinical consequences of IE and the increment in health care costs it imposes on patients with MVP remain uncertain. Accordingly, 21 MVP patients with IE and 41 age- and sex-matched control subjects with initially uncomplicated MVP were followed (95% complete) a mean of 8 years. Outcomes included death, complications, health care use and cumulative incremental costs. More MVP patients with IE died (25 vs 5%, p < 0.05), underwent valve surgery (40 vs 8%, p < 0.01), had heart failure (50 vs 5%, p < 0.01) or embolization (53 vs 11%, p < 0.01), underwent cardiac catheterization (40 vs 13%), and saw their physicians > 2 times per year (88 vs 33%). The cumulative incremental cost of IE (1990 dollars) was $46,132 per case. Thus, IE in patients with MVP causes considerable cumulative morbidity and incremental health care costs.

Endocarditis caused by Neisseria elongata subspecies nitroreducens: case report and literature review

Neisseria elongata subsp. nitroreducens, an usual commensal of the nasopharynx, can cause serious infections, usually endocarditis. A case of Neisseria elongata endocarditis complicating mitral valve prolapse in a patient allergic to penicillin is reported. Cure was obtained with a combination of ceftriaxone and gentamicin, there being no requirement for surgery during the acute phase of the disease.

Pediatric infective endocarditis in the modern era

Sixty-two cases of endocarditis occurring in children between January 1977 and February 1992 were reviewed and compared with series from the 1970s and early 1980s. Changes in risk factors, pathogens, diagnostic modalities, and outcome were determined. Complex congenital heart disease (22 cases) and unrepaired ventricular septal defect (9 cases) were the most common underlying lesions. A total of 19 children with normal anatomy had endocarditis; 6 had community-acquired infection and 13 had hospital-acquired endocarditis (11 of these 13 children had central venous catheters in place, including 7 premature infants). Echocardiograms revealed vegetations in 25 of 49 patients; 24 of these patients had positive echocardiographic findings on the first study. Echocardiographic findings were most often negative in children with complex cyanotic heart disease. Staphylococcus aureus (39%) was the most common pathogen isolated and was associated with a higher incidence of central nervous system complications (p < 0.0015) and a greater need for surgical intervention (p = 0.01) than were other pathogens. Methicillin-resistant S. aureus (eight cases) and coagulase-negative staphylococci (three cases) emerged as important pathogens but were not associated with increased morbidity or mortality rates. Fungal endocarditis (six cases) had a 67% mortality rate. Overall the mortality rate was 11%. Endocarditis remained undiagnosed in seven seriously ill patients until postmortem examination. This study indicates that, during the past decade, important changes in risk factors, pathogens, and the susceptible population have altered the presentation and management of endocarditis in children.

[Infectious endocarditis, risk factors, prevention. Research group for infectious endocarditis and jury of the consensus conference]

Infective endocarditis, resulting from deposition of circulating microorganisms during a period of bacteremia on damaged endothelial heart valves, remains a serious disease. Its overall incidence did not decline in recent years, 24 cases/year/million inhabitants, in France. This can be explained by a modification of the type of underlying cardiac conditions with regression of rheumatic fever and increase of degenerative heart diseases, prosthetic valves and mitral valve prolapse. The risk of bacterial seeding on a damaged valve remains difficult to evaluate, the highest risk being for patients with prosthetic valve, previous infective endocarditis and cyanotic congenital heart disease. A case-control study, done in 1991, confirmed that procedures are risk factors for infective endocarditis and that the multiplicity of procedures increases the risk. A French consensus conference on the prophylaxis of infective endocarditis has updated the recommendations for antibiotic prophylaxis. Two groups of cardiac patients were identified, based on the incidence and the severity of endocarditis occurring in patients with these conditions, 1) patients considered at risk which require specific prophylaxis, and 2) patients considered non at risk which do not require antibiotic prophylaxis. Procedures which require antibiotic prophylaxis are dental procedures and specific gastrointestinal and urologic procedures. As complex protocols are associated with poor compliance by practitioners and patients, the jury has aimed for simplicity and feasibility.

Mild dehydration induces echocardiographic signs of mitral valve prolapse in healthy females with prior normal cardiac findings

This study was designed to investigate the hypothesis that mitral valve prolapse (MVP) can be induced after diuresis in women without the abnormality who have characteristic body habitus. Fifteen tall, slim, healthy female volunteers with a normal cardiac findings, echocardiogram, and history were investigated after mild diuresis with furosemide and after placebo. All subjects lost weight after furosemide and placebo administration; but mean weight loss was significantly greater after furosemide administration than after placebo administration. Echocardiography showed MVP in none of the 15 patients before treatment, in seven after administration of placebo, and in seven after administration of furosemide. Coaptation point prolapsed superior to the anulus in seven subjects with echocardiographically determined MVP. Left ventricular end-diastolic dimensions decreased significantly after placebo or furosemide administration in subjects in whom MVP developed compared with the measurement in those in whom MVP did not develop. Murmurs characteristic of MVP disappeared in all four rehydrated subjects and echocardiographic changes resolved in two of the five rehydrated subjects. Thus echocardiographically determined MVP can be induced by mild dehydration in women with phenotypic body habitus of MVP; changes may resolve with rehydration. Results suggest an explanation for variable physical examination findings in persons with MVP.

The changing pattern of infective endocarditis in childhood

Forty-eight cases of infective endocarditis (IE) that occurred in 42 patients with congenital heart disease were reviewed from 1970 through 1990 and were compared with a 20-year review of 108 cases diagnosed between 1953 and 1972. The review demonstrates that the natural history of IE in children has changed over the last 2 decades, with half of the cases occurring after surgery for congenital heart disease. In the postoperative group, 46% of patients had undergone valve replacement and 7 of these (29%) had a right ventricular to pulmonary artery valved conduit as the site for IE, suggesting significant additional risk in this setting. Among patients with nonsurgically treated congenital heart disease and IE, mitral valve prolapse has emerged as an important underlying heart lesion occurring in 29% of patients. The bacterial spectrum has shifted, with a significant increase in the incidence of uncommon causative organisms. Mortality has continued to decline with survivorship of 90% in this series.

Infective endocarditis caused by Streptococcus suis serotype 2

Infective endocarditis caused by Streptococcus suis serotype 2 is not uncommon in pigs but is rare in human beings. We describe the case of a pig-farmer with endocarditis due to S. suis serotype 2 and in whom prolapse of the mitral valve was the predisposing cardiac lesion. Streptococcus suis, a possible cause of infective endocarditis in endemic areas, may be confused with other group D streptococci. In suspected cases a history of contact with pigs or raw pork should be sought.