Surgical pathology of native valve endocarditis in 310 specimens from 287 patients (1985–2004)

The Forensic Perspective of Infectious Endocarditis: A Retrospective Study With Recommendations for the Future

Increasing rates of infectious endocarditis (IE) are well-described in the United States and worldwide, yet forensic literature regarding IE is sparse. Autopsy databases may help identify subsets of patients at increased risk of mortality. We reviewed all deaths due to IE in our office between 2010 and 2022 (with full autopsy performed) and found 29. The average age was 44 years. Manners of death included natural (69%), accident (28%), and homicide (3%). For all accidental deaths, acute intoxication was included in either part I or II. The aortic valve was most affected (62%), followed by tricuspid (28%) and mitral (24%). Seventy-six percent of affected valves were native, and 24% were prosthetic. Common risk factors included intravenous drug use (48%) and chronic ethanolism (21%). No sustained increase in deaths due to IE was identified. These data show marked differences from clinical literature, including a lower average age and higher incidence of substance use disorders, and it is unlikely selection bias is the sole reason. There was inconsistency in death certification, most notably by not including pertinent IE risk factors. Improving consistency and quality of IE death certification will aid in detecting regional trends and assist multi-institutional collaboration efforts.

Bicuspid aortic valve: The most frequent and not so benign congenital heart disease

Bicuspid aortic valve (BAV) is the most frequent congenital heart disease, with an incidence of approximately 1%. It can be silent and associated with normal valve function. However, a series of complications, even catastrophic, may occur with time: valve incompetence, valve stenosis by dystrophic calcification, infective endocarditis, progressive dilatation of the ascending aorta, aortic dissection, sudden death. The problem of BAV is not just about the number of semilunar cusps, but also the aortic wall. Severe noninflammatory degenerative changes (elastic fiber fragmentation, smooth muscle cells death, mucoid extracellular matrix accumulation=MEMA) are observed in the aortic wall of BAV patients, with intrinsic weakness accounting for progressive aneurysmal dilatation of the ascending aorta, valve incompetence, and wall dissection. The link between valve and aortic wall pathology finds most probably an explanation in the embryology of the arterial pole since neurocrestal cells play a role in the development of both the ascending aorta, aortic arch, and semilunar valves. The frequent association of adult aortic coarctation and BAV provides evidence for this hypothesis. BAV has a significant genetic component as to require screening of first-degree relatives, as outlined by AHA/ACC 2022 guidelines.

Beyond Aortic Stenosis: Addressing the Challenges of Multivalvular Disease Assessment

Aortic stenosis (AS) can often coexist with other valvular diseases or be combined with aortic regurgitation (AR), leading to unique pathophysiological conditions. The combination of affected valves can vary widely, resulting in a lack of standardized diagnostic or therapeutic approaches. Echocardiography is crucial in assessing patients with valvular heart disease (VHD), but careful consideration of the hemodynamic interactions between combined valvular defects is necessary. This is important as it may affect the reliability of commonly used echocardiographic parameters, making the diagnosis challenging. Therefore, a multimodality imaging approach, including computed tomography or cardiac magnetic resonance, is often not just beneficial but crucial. It represents the future of diagnostics in this intricate field due to its unprecedented capacity to quantify and comprehend valvular pathology. The absence of definitive data and guidelines for the therapeutic management of AS in the context of multiple valve lesions makes this condition particularly challenging. As a result, an individualized, case-by-case approach is necessary, guided primarily by the recommendations for the predominant valve lesion. This review aims to summarize the pathophysiology of AS in the context of multiple and mixed valve disease, with a focus on the hemodynamic implications, diagnostic challenges, and therapeutic options.

Pathology of the Aortic Valve: Aortic Valve Stenosis/Aortic Regurgitation

PURPOSE OF REVIEW

This discussion is intended to review the anatomy and pathology of the aortic valve and aortic root region, and to provide a basis for the understanding of and treatment of the important life-threatening diseases that affect the aortic valve.

RECENT FINDINGS

The most exciting recent finding is that less invasive methods are being developed to treat diseases of the aortic valve. There are no medical cures for aortic valve diseases. Until recently, open-heart surgery was the only effective method of treatment. Now percutaneous approaches to implant bioprosthetic valves into failed native or previously implanted bioprosthetic valves are being developed and utilized. A genetic basis for many of the diseases that affect the aortic valve is being discovered that also should lead to innovative approaches to perhaps prevent these disease. Sequencing of ribosomal RNA is assisting in identifying organisms causing endocarditis, leading to more effective antimicrobial therapy. There is exciting, expanding, therapeutic innovation in the treatment of aortic valve disease.

Tricuspid and Pulmonic Valve Pathology

PURPOSE OF REVIEW

This review describes the normal structure and pathologic changes that affect the right-sided cardiac valves and chambers.

RECENT FINDINGS

The anatomy and pathology described have been known for many years. Knowledge of these findings has gained relevance. The pattern of endocarditis is changing. New diagnostic techniques have allowed better characterization of lesions responsible for cardiac dysfunction. Novel, less invasive interventions have made recognition of abnormalities more clinically relevant. There are many different pathologic entities that can affect the right-sided cardiac valves. These are discussed in this review.

Early results for active infective endocarditis

Introduction

Cardiac surgery is frequently needed during active phase of infective endocarditis (IE). The purpose of this study was to analyze the immediate and late results and determine the risk factors for death.

Methods

We retrospectively reviewed 101 patients with IE operated in the active phase. The mean age was 40.5 ± 12.5 years. 16 patients (15.8%) were diagnosed with prosthetic valve endocarditis (PVE). 81 (80.9%) were in NYHA functional class III-IV. Blood cultures were positive in only 24 cases (23.9%).

Results

in-hospital mortality rate was 17.9% (18 cases). Multivariate analysis indentified five determinant predictor factors: congestive heart failure (CHF), renal insufficiency, high Euroscore, prolonged cardiopulmonary bypass time (> 120 min) and long ICU stay. The median follow-up period was 4.2 (2-6.5) years. Overall survival rate for all patients who survived surgery was 97% at 5 years and 91% at 10 years.

Conclusion

Despite high in-hospital mortality rate, when patients receive operation early in the active phase of their illness, late outcome may be good.

Fatal endocarditis with methicilin-sensible Staphylococcus aureus and major complications: rhabdomyolysis, pericarditis, and intracerebral hematoma: A case report and review of the literature

BACKGROUND

Over the last decades Staphylococcus aureus (SA) has become the dominant etiology of native valve infective endocarditis, with the community-acquired methicillin-sensible Staphylococcus aureus (CA-MSSA) strains being the prevailing type.

CASE

We report here a case of extremely severe CA-MSSA aortic valve acute endocarditis associated with persistent Staphylococcus aureus bacteremia (SAB) in a previously healthy man and include a literature review.The patient developed severe and rare complications (purpura, purulent pericarditis, intracerebral hematoma, and rhabdomyolysis) through systemic embolism; they required drainage of pericardial empyema and cerebral hematoma, the latter eventually caused a fatal outcome. The strains recovered from sequential blood culture sets and pericardial fluid were MSSA negative for genes encoding for staphylococcal toxic shock syndrome toxin (TSST)-1 and Panton-Valentine leukocidin. C, G, and I enterotoxin genes were detected.

CONCLUSIONS

This case with unusually severe evolution underlines the limited ability of vancomycin to control some MSSA infections, possibly due to potential involvement of SA virulence factors, hence the importance of clinical vigilance for community SAB cases.

Association of Mitral Valve Prolapse With Infective Endocarditis Due to Viridans Group Streptococci

Although patients with certain cardiac valve abnormalities have increased risk of infective endocarditis (IE), it is unknown whether these abnormalities are associated with specific pathogens in IE cases. We report a strong association between mitral valve prolapse and viridans group streptococcal IE in a population-based cohort from Olmsted County, Minnesota.

Clinical features, microbiology and surgical outcomes of infective endocarditis: a 13-year study from a UK tertiary cardiothoracic referral centre

BACKGROUND

Infective endocarditis (IE) causes substantial morbidity and mortality. Patient and pathogen profiles, as well as microbiological and operative strategies, continue to evolve. The impact of these changes requires evaluation to inform optimum management and identify individuals at high risk of early mortality.

AIM

Identification of clinical and microbiological features, and surgical outcomes, among patients presenting to a UK tertiary cardiothoracic centre for surgical management of IE between 1998 and 2010.

DESIGN

Retrospective observational cohort study.

METHODS

Clinical, biochemical, microbiological and echocardiographic data were identified from clinical records. Principal outcomes were all-cause 28-day mortality and duration of post-operative admission.

RESULTS

Patients (n = 336) were predominantly male (75.0%); median age 52 years (IQR = 41-67). Most cases involved the aortic (56.0%) or mitral (53.9%) valves. Microbiological diagnoses, obtained in 288 (85.7%) patients, included streptococci (45.2%); staphylococci (34.5%); Haemophilus, Actinobacillus, Cardiobacterium, Eikenella, Kingella (HACEK) organisms (3.0%); and fungi (1.8%); 11.3% had polymicrobial infection. Valve replacement in 308 (91.7%) patients included mechanical prostheses (69.8%), xenografts (24.0%) and homografts (6.2%). Early mortality was 12.2%, but fell progressively during the study (P = 0.02), as did median duration of post-operative admission (33.5 to 10.5 days; P = 0.0003). Multivariable analysis showed previous cardiothoracic surgery (OR = 3.85, P = 0.03), neutrophil count (OR = 2.27, P = 0.05), albumin (OR = 0.94, P = 0.04) and urea (OR = 2.63, P < 0.001) predicted early mortality.

CONCLUSIONS

This study demonstrates reduced post-operative early mortality and duration of hospital admission for IE patients over the past 13 years. Biomarkers (previous cardiothoracic surgery, neutrophil count, albumin and urea), predictive of early post-operative mortality, require prospective evaluation to refine algorithms, further improve outcomes and reduce healthcare costs associated with IE.

Coagulase-negative staphylococci

The definition of the heterogeneous group of coagulase-negative staphylococci (CoNS) is still based on diagnostic procedures that fulfill the clinical need to differentiate between Staphylococcus aureus and those staphylococci classified historically as being less or nonpathogenic. Due to patient- and procedure-related changes, CoNS now represent one of the major nosocomial pathogens, with S. epidermidis and S. haemolyticus being the most significant species. They account substantially for foreign body-related infections and infections in preterm newborns. While S. saprophyticus has been associated with acute urethritis, S. lugdunensis has a unique status, in some aspects resembling S. aureus in causing infectious endocarditis. In addition to CoNS found as food-associated saprophytes, many other CoNS species colonize the skin and mucous membranes of humans and animals and are less frequently involved in clinically manifested infections. This blurred gradation in terms of pathogenicity is reflected by species- and strain-specific virulence factors and the development of different host-defending strategies. Clearly, CoNS possess fewer virulence properties than S. aureus, with a respectively different disease spectrum. In this regard, host susceptibility is much more important. Therapeutically, CoNS are challenging due to the large proportion of methicillin-resistant strains and increasing numbers of isolates with less susceptibility to glycopeptides.

Changing profile of infective endocarditis: a clinicopathologic study of 220 patients in a single medical center from 1998 through 2009

The epidemiologic profile of infective endocarditis has changed substantially over the past few years, especially in industrialized countries. Our study evaluates the clinical and pathologic characteristics of infective endocarditis patients treated by cardiac surgery in China during a 12-year period. We retrospectively evaluated 220 surgically treated infective endocarditis patients and analyzed their changes from the beginning of 1998 through 2009. The mean age of the patients increased from 36.9 to 42.7 years during those 12 years (P=0.036). The chief predisposing disease was congenital heart disease (32.8%), rather than rheumatic heart disease (13.2%); this rate did not change significantly during the 12 years. The prevalent congenital lesion was bicuspid aortic valve, the rate of which (55.6%) increased significantly over the 3 time intervals studied (P=0.016). The frequency of infective endocarditis after non-dental surgical and nonsurgical intervention was significantly greater (23.3%) during 1998 through 2001, compared with the 2 intervals that followed (9%; P=0.019). Streptococcus viridans was the most frequent causative agent overall (25.6%). Forty-seven of the 220 patients (21.4%) carried the clinical diagnosis of some other form of heart disease before surgery, but at surgery they were found to have infective endocarditis as the fundamental disease process. Of 47 patients, 33 (70.2%) had either very small or no vegetations but had focal necrosis and inflammation of valve tissue that supported the diagnosis of infective endocarditis.

Cell wall-anchored nuclease of Streptococcus sanguinis contributes to escape from neutrophil extracellular trap-mediated bacteriocidal activity

Streptococcus sanguinis, a member of the commensal mitis group of streptococci, is a primary colonizer of the tooth surface, and has been implicated in infectious complications including bacteremia and infective endocarditis. During disease progression, S. sanguinis may utilize various cell surface molecules to evade the host immune system to survive in blood. In the present study, we discovered a novel cell surface nuclease with a cell-wall anchor domain, termed SWAN (streptococcal wall-anchored nuclease), and investigated its contribution to bacterial resistance against the bacteriocidal activity of neutrophil extracellular traps (NETs). Recombinant SWAN protein (rSWAN) digested multiple forms of DNA including NET DNA and human RNA, which required both Mg²⁺ and Ca²⁺ for optimum activity. Furthermore, DNase activity of S. sanguinis was detected around growing colonies on agar plates containing DNA. In-frame deletion of the swan gene mostly reduced that activity. These findings indicated that SWAN is a major nuclease displayed on the surface, which was further confirmed by immuno-detection of SWAN in the cell wall fraction. The sensitivity of S. sanguinis to NET killing was reduced by swan gene deletion. Moreover, heterologous expression of the swan gene rendered a Lactococcus lactis strain more resistant to NET killing. Our results suggest that the SWAN nuclease on the bacterial surface contributes to survival in the potential situation of S. sanguinis encountering NETs during the course of disease progression.

Diastolic aorto-right-atrial fistulation in aortic and tricuspid valve endocarditis

Background Aorto–right-atrial fistula in native valve endocarditis is very rare.

Case Description A 45-year-old woman was referred with an endocarditis with a perforated right cusp of the aortic valve with at least moderate insufficiency and an affected tricuspid annulus with vegetations. In addition to this, an aorto-cavitary fistula from the aortic sinus to the right atrium with a holodiastolic left–right shunt had been detected. Streptococci viridans were found as underlying pathogen. Complete replacement of the aortic root and resection of the fistula were performed with good result.

Conclusion Endocarditis with fistula formation is rare and has to be treated aggressively.

Pathologic findings in native infective endocarditis

BACKGROUND

There are few studies on the histologic findings in native infective endocarditis, especially regarding mimics of autoimmune valvulitis.

METHODS

We prospectively studied 106 surgical specimens from 95 patients with a clinical diagnosis of infective endocarditis on native valves, and compared gross and histologic findings with culture results, underlying valve disease, risk factors and time interval from symptom onset to surgical intervention.

RESULTS

There were 41 (39%) aortic, 33 (31%) mitral, 9 (9%) tricuspid, 1(.9%) pulmonic and 11 (10%) multiple valve replacements. Underlying valve disease was present in 26 (27%) patients (non-calcified bicuspid aortic valve, 10 (38%) cases; mitral valve prolapse, 5 (19%) cases; calcified trileaflet aortic valve, 5 (19%) cases; calcified bicuspid aortic valve, 2 (8%) cases; post-rheumatic mitral valve disease, 2 (8%) cases; hypertrophic cardiomyopathy-related mitral valve disease, 1 (4%) case, trileaflet aortic insufficiency 1 (4%) case) and associated with streptococcal infection (p = .001). Absence of underlying valve disease was associated with intravenous drug abuse (p = .01) and dialysis dependent renal disease (p = .006). Intravenous drug abuse was associated with staphylococcal infection (p = .03). Vegetations were present in 80 (75%) of cases, and on the nonflow surface of the valve in 65 (81%) of these. Gram-stain positivity and neutrophilic microabscesses were associated with staphylococcal infection (p = .03). Epithelioid macrophages with palisading features mimicking necrobiotic granulomas were seen in 42 (40%) valves and more frequently associated with streptococcal infection (p=.03). As expected, the presence of valve necrosis and acute inflammation decreased with an increase in time with respect to symptomatic onset.

CONCLUSION

Histologic findings that mimic autoimmune inflammation are frequent in infective endocarditis and associated with streptococcal infection. Risk factors for infective endocarditis include calcific valve disease.

Case records of the Massachusetts General Hospital: Case 5-2014: 2014: A 59-year-old man with fever, confusion, thrombocytopenia, rash, and renal failure

A 59-year-old man was admitted to this hospital because of fever, confusion, rash, thrombocytopenia, and renal failure, 10 days after a hunting trip in the Nevada valley. Diagnostic procedures were performed, and diagnostic test results were received from another hospital.

Clinical characteristics of infections in humans due to Staphylococcus epidermidis

Staphylococcus epidermidis is the most common cause of primary bacteremia and infections of indwelling medical devices. The ability to cause disease is linked to its natural niche on human skin and ability to attach and form biofilm on foreign bodies. This review focuses on the S. epidermidis clinical syndromes most commonly encountered by clinicians and future potential treatment modalities.

Successful treatment, despite a non-surgical approach, of severe infective endocarditis

A 60-year-old man with a history of Child-Pugh class B cirrhosis was admitted to the hospital with 4-5 days of nausea, vomiting and altered mental status. Following the development of fever in the intensive care unit and methicillin-sensitive Staphylococcus aureus bacteraemia, a large (15 mm) vegetation was discovered on the anterolateral papillary muscle of the mitral valve. Following a thorough multidisciplinary evaluation, the patient was considered to be a poor surgical candidate due to the significant perioperative complications associated with Child-Pugh class B cirrhosis. The patient was treated with 6 weeks intravenous nafcillin as an outpatient. Echocardiography following the treatment course revealed that the vegetation had completely resolved without any valvular dysfunction. This case report emphasises that medical management remains an effective alternative to surgery in complicated cases of infective endocarditis.

Paravalvular abscess of the mitral valve with fistula to the left ventricle and detachment of the coronary sinus in a young woman

Infective endocarditis (IE) of the mitral valve (MV) manifesting paravalvular abscess (PA) is challenging. A 30-year-old woman presented with PA fistulating to the left ventricle, detachment of the coronary sinus and systemic embolization. During a course of fever of unknown origin, the patient received laparoscopic surgery under the diagnosis of strangulating intestinal obstruction due to colitis. Following abdominal surgery, abscess having blood flow within it from the left ventricle was pointed out at the left ventriculo-atrial junction by transthoracic echocardiography. Emergency surgery was performed under the diagnosis of PA of MV. Abscess debridement followed by reconstruction of the mitral annulus and coronary sinus with fresh autologous pericardium and mitral valve replacement (MVR) using a mechanical prosthetic valve were successfully performed. Timely and accurate diagnosis followed by the early surgical intervention with aggressive debridement of abscess and reconstruction with autologous pericardium should improve the outcome of this high-risk disease.