Patient 2: endocarditis on structurally normal aortic valve; repeated admissions with headache and positive blood cultures (Gram-positive cocci) 2 weeks preadmission; new murmur 2 days postdelivery; echocardiogram showed aortic valve vegetations; sudden collapse.
Patient 3: had SLE, died during termination of nonviable pregnancy; nonspecifically unwell, autopsy showed Libman–Sacks endocarditis.a
Patient 2: known coarctation of aorta (postsurgery); died after mitral and aortic valve replacements and CS.
Patient 3: no known cardiac anomaly; pyrexia of unknown origin; repeated self-discharge; died 4 weeks post CS; autopsy diagnosis.
a Libman–Sacks endocarditis is found in approximately 50% of patients with SLE and is characterized by sterile vegetations on the heart valves; secondary infective endocarditis was not found in this woman; this case has a different etiology from infective endocarditis
b Full data not available for each triennium
CS = cesarean section; DVT = deep venous thrombosis; GBS = group B streptococcus; IDD = insulin-dependent diabetes; IVDU = intravenous drug use; LVF = left ventricular failure; N/A = not available; SLE = systemic lupus erythematosus; SUDEP = sudden death in epilepsy
Preventative measures
It is not known whether prophylactic antibiotics, given at the time of dental work, gastrointestinal/genitourinary instrumentation, or childbirth, can prevent endocarditis. Most cases of endocarditis are not attributable to an invasive procedure and, historically, recommendations for the use of prophylactic antibiotics have varied considerably in different countries.[31]
Historically, advice regarding the use of antibiotic prophylaxis for normal vaginal delivery has been mixed. Some specialists felt that the theoretical benefit, together with the severe consequences of endocarditis in a high-risk woman, made antibiotic administration a prudent, if not an evidence-based, strategy.[32] However, the indication for antibiotic prophylaxis has been significantly reduced in more recent guidelines from the ESC and AHA.[2,4] Guidelines were reviewed because of a combination of concerns about a lack of evidence of efficacy and overuse of antibiotics, which may result in an increase in resistant organisms.[2,4] There have also been concerns about the effect of excessive antibiotic use in pregnancy on neonates.[33,34] The National Institute for Health and Care Excellence (NICE) in the UK recommended cessation of the practice of antibiotic prophylaxis for endocarditis in all cases in 2008.[35] New guidelines from the ESC and AHA followed: these recommended prophylactic antibiotic use in some patients undergoing high-risk procedures where there is a high risk of endocarditis occurring. Those with the highest risk are defined as those with prosthetic heart valves, prosthetic materials in the heart (placed either surgically or percutaneously), previous endocarditis, or cyanotic CHD, which is either unrepaired or with residual defects, palliative shunts, or conduits. It is also recommended for 6 months after the repair of CHD with prosthetic material or when a residual defect is adjacent to prosthetic material. (see Table 19.1) [2,4] The high-risk procedures are defined as “dental procedures requiring manipulation of the gingival or periapical region of the teeth or perforation of the oral mucosa.”[4] Recent evidence, however, suggests that the incidence of endocarditis has increased in the UK by 25% since the adoption of the 2008 NICE guidelines and NICE has announced that it will re-examine its guidelines as a result of this new data.[36]
There is no evidence that prophylactic administration of antibiotics will prevent endocarditis following uncomplicated vaginal delivery, and current obstetric guidelines do not support the use of prophylactic antibiotics during normal delivery, operative delivery, manual removal of the placenta, postpartum dilatation and curettage for retained products of conception, or elective or emergency cerclage, or for any genitourinary procedure.[33,37] Antibiotics are recommended, however, for women undergoing elective or emergency cesarean section (single dose for routine cases) because they have been shown to substantially reduce postoperative sepsis from wound infection and endometritis.[35] Antibiotics can be considered for women undergoing repair of a third or fourth degree perineal injury.[33,37] Similarly, preterm prelabor rupture of the membranes is associated with bacteremia, and administration of antibiotics reduces maternal and fetal infectious morbidity.[38]
Serious noncardiac infection can result in septicemia; indeed, this was the cause of death of one woman in the 2011 UK enquiry into maternal deaths.[30] The possibility of endocarditis should always be considered in a woman who is refractory to standard treatment for a noncardiac infection. Therefore, in the case of established infection elsewhere or if antibiotics are being given to prevent wound infection, it is reasonable to use an agent that is active against enterococci (such as ampicillin, amoxicillin or, in cases of beta-lactam allergy, vancomycin).[39]
From a dental point of view, to prevent an oral inflammatory process evolving into a full-blown form of periodontitis with recurrent bacteremia, mothers should receive regular professional oral hygiene care throughout pregnancy, particularly if they are at a high risk.[40]
Interestingly, since the advent of the new NICE guidelines, although it is unclear whether or not the incidence of endocarditis has increased,[41,42] many practitioners are still prescribing more antibiotics than recommended.[43] This may be a manifestation of “defensive medicine.”
Protocol for prevention, diagnosis, and treatment of endocarditis in pregnancy
A protocol for the prevention, diagnosis, and treatment of endocarditis in pregnancy is described below. Intravenous drug users should be treated similarly to “high-risk” cardiac patients.
Prevention
Prevention of endocarditis in pregnancy in women with structural heart disease should begin with education. Many patients and their families have a poor understanding of the risks of endocarditis.[44] Endocarditis risk should be discussed repeatedly during childhood and should be rediscussed on transfer to adult cardiology follow-up. There is considerable evidence that “at risk” women benefit from being given regular, repeated, and written advice concerning measures that will minimize the risk of endocarditis.[44] This should include the need for good dental hygiene, avoidance of intravenous drug abuse, and early treatment of skin sepsis. Women should receive professional oral hygiene care throughout pregnancy. Unfortunately, it is thought that 30% of the population do not attend a dentist regularly.[39] Even for those with CHD, the uptake is less than ideal, with many citing anxiety/dislike as the main reason for this.[45]
With respect to delivery in low-risk cases, it is important to state clearly that no antibiotic prophylaxis is required but that any suspected infection (especially urinary tract, chorioamnionitis, or wound infection) should be treated promptly with intravenous antibiotics as per the usual local protocols. Routine prophylaxis should be given for third degree tears and cesarean section. In high-risk cases (Table 19.1), we recommend that any antibiotics used for peripartum infections cover enterococci, i.e. ampicillin, gentamicin, or vancomycin.
Diagnosis
A high index of suspicion is particularly important for “at risk” women. The diagnosis of endocarditis in pregnancy should be made using the modified Duke criteria (Table 19.4). If endocarditis is suspected, at least three sets of blood cultures should be taken using optimal antiseptic skin preparation. Samples should be taken for both aerobic and anaerobic culture, and appropriately modified culture medium should be used if antibiotics have been given. There is no rationale for waiting until pyrexia occurs before taking blood samples for culture.[46] Positive blood cultures in a febrile or unwell woman should never be ignored. Similarly, new cardiac murmurs in the context of a febrile woman should not be assumed to be harmless. Endocarditis should also be considered in cases of embolic stroke. If endocarditis is suspected, early cardiology assessment should be sought and echocardiography carried out promptly. Although around 90% of patients present with fever, night sweats, anorexia, and weight loss, the clinical presentation can vary and should be considered in any woman with undiagnosed infection and features that may suggest endocarditis.
| Major criteria |
| Positive blood cultures (>2) of a “typical” organism (e.g. Streptococcus viridans or S. aureus in the absence of primary focus) |
| Endocardial involvement (requires echocardiogram): |
| Vegetation on valve |
| Abscess |
| New dehiscence of prosthetic material |
| New valve regurgitation |
| Minor criteria |
| Predisposing cardiac condition or intravenous drug abuse |
| Fever >38°C |
| Vascular factors (for example emboli or mycotic aneurysms) |
| Immunological factors (for example glomerulonephritis, Osler nodes) |
| Microbiology (for example positive blood cultures not meeting major criteria) |
| Definite endocarditis = 2 major criteria |
| Or 1 major and 3 minor criteria |
| Or 5 minor criteria |
| Or pathology/bacteriological evidence from vegetation or emboli |
| Possible endocarditis = 1 major and 1 minor criteria |
| Or 3 minor criteria |
| Not endocarditis = firm alternative diagnosis |
| Or does not meet criteria above |
| Or resolution of symptoms after <4 days antibiotics |
| Or no pathological evidence at surgery/autopsy after <4 days treatment |
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