cardiac infections

Acute Infective Endocarditis (AIE)

(higher fever, affects normal valves)

Subacute Bacterial Endocarditis (SBE)

(low grade fever, affects abnormal valves)

viral infections can cause infectious myocarditis

-Coxsackie (especially B) -Adenovirus -HIV - most common pathology at autopsy of AIDS patients

treatment myocarditis from cruzi

Benznidazone or nifurtimox

Pericarditis Diagnosis

CBC : leukocytosis suggests infection Serum electrolyte, BUN -rule out kidney ESR and CRP Cardiac biomarkers - creatine kinase, LDH, SGOT (AST), Troponin I Blood cultures - looking for bacterial cause Tuberculin test Anti-streptolysin O titer

virulence factor for staph

Coagulase encases bacteria in fibrin; leukocidins (Panton-valentine leukocidin, PVL) kill phagocytes

Most common viral cause of infectious pericarditis

Coxackievirus B

Clusters of black cocci represent typical

Endocarditic

Corynebacterium diphtheriae

Gram positive rod, nonspore forming. Diphtheria toxin stops host protein synthesis. Organism stays in the throat, toxin disseminates, predilection for heart

Staphylococcus aureus

Gram-positive cocci Grape-like clusters, catalase positive, coagulase positive. Found on skin, nares. Transmitted by direct or indirect contact.

HACEK Gram-negative organisms

Haemophilus species, Aggregatibacter [formerly Actinobacillus] actinomycetemcomitans, Cardiobacterium hominis, Eikenella corrodens, and Kingella species

36 year-old woman comes to the ED complaining of low grade fever and chills. She says she has been losing weight over the past several weeks. She is tired, experiences shortness of breath and has a mild but persistent cough. Physical examination reveal splinter hemorrhages in some of her fingernails

Infectious Endocarditis

most common form of cardiac infection valves

Infectious Endocarditis (IE)

infectious pericarditis

Inflammation triggered by infection causes pericardial effusion, leads to increased pressure on heart (CARDIAC TAMPONADE), Chest pain prominent, positional (worse supine than upright) Hear pericardial friction rub upon auscultation (triphasic grating sound)

General Treatment of Myocarditis

Treat heart failure with digoxin, diuretics, ACE inhibitors, salt restriction Treat arrhythmia (quinidine or procainamide) Anticoagulation to prevent thromboembolism

Myocarditis Protozoan Infection

Trypanosoma cruzi

An otherwise healthy 26-year-old woman who was hospitalized when she returned from a 2-month stay in French Guiana. Her symptoms included fever, headache, photophobia, intermittent chest pain, arthromyalgia, and generalized lymphadenopathy. Physical examination showed unilateral periorbital swelling (Figure). No abnormalities were found on clinical workup; blood smears and cultures were negative. Results of lumbar puncture, chest radiography, and echocardiography were also negative. The electrocardiogram (ECG) showed anterior ST-segment depression. A smear of a blister adjacent to the eye showing the Romaña sign yielded Trypanosoma cruzi on direct examination. The patient was treated orally with benznidazole, 150 mg twice a day, and had a good clinical response

acute myocarditis

Etiology of Infectious Myocarditis:

bacterial: diphtheria lyme: borrelia

vegetations are

biofilm that •Secrete a polysaccarides that effectively allows the bacteria to aggregate

diagnose myocarditis

blood smear antibody test

hallmark of myocarditis

cardiomegaly

Viridans Streptococci

catalase neg •Normal oral flora - S. mutans • Alpha hemolytic Streptococcus mutans Tooth decay •Low virulence • Subacute bacterial endocarditis

Infectious Endocarditis damage

damaged heart valves mostly mitral or prosthetic valve

Fever, chills, weight loss, malaise, dyspnea, cough,

endocarditis

Pathogenic Mechanisms of Infectious Endocarditis

endothelial damage activate cascade of sticky repair if bacteria is in blood it will stick to this poorly repaired tissue vegetation grows on valve

coxsackie A and B

enterovirus resistant to pH 3 to pH 9, detergents, mild sewage treatment, and heat fecal-oral transmission

drug associated

eosinophils

idiopathic

giant cells (cluster of macrophages)

Group D Streptococci Streptococcus gallolyticus

gram positive Most strains are non-hemolytic, others alpha hemolytic, associated with colon cancer can include Enterococcus faecalis Enterococcus faecium

viral

lymphocytes

chest pain (in conjunction with pericarditis), fever, sweats, chills and dyspnea Arrhythmias

myocarditis

HACEK organism will often result in

neg blood culture

bacteria

neutrophils

key to Infectious Pericarditis

pericardial sac

patient's major complaint are palpitations. Chest pain is the cardinal sign Can be sharp, dull, aching, burning, usually precordial (area of chest over the heart) or retrosternal (pain behind sternum, usually upon swallowing), ECG changes, Dyspnea, tamponade.

pericarditis

Infectious Myocarditis (IM)

rare in immunocompetent, usually seen in immunocompromised patients, often a consequence of overwhelming sepsis

Infectious Pericarditis (IP)

rare, usually follows a respiratory infection

Treatment of enterococci difficult-

resistant to penicillins, BUT effective synergy occurs when a cell wall inhibitor (ampicillin or vancomycin) and an aminoglycoside

Endocarditis Associated with Prosthetic Valves

staph aureus or coagulase-negative staphylococci (e.g. S. epidermidis)

IV drug abuse Indwelling catheters infection in

tricuspid valve

Infectious Myocarditis key to disease

ventricles

Signs and Symptoms of Myocarditis

•Abnormal heartbeat (AV block, ventricular tachycardia) •Chest pain (may resemble a heart attack) •Fatigue •Fever and other signs of infection including headache, muscle aches, sore throat, diarrhea, or rashes •Decreased urine output •Arthralgia or swelling •Lower extremity edema •Shortness of breath (rales, etc.) Syncope

Trypanosoma cruzi

•American Trypanosomiasis (Chagas Disease) - affects 20 million people worldwide (common in South America), rare in the US unless a traveler •Infects Reduvid bug, Triatomine bugs, and small mammal reservoirs •Crawling insect, bites while you sleep, thin skin over eyes, orbital infection (Romaňa's sign), infection is lifelong, leads to cardiac and GI problems.

IE Risk Factors

•Congenital heart abnormalities (e.g., mitral valve prolapse) •Structural defects (traumatic, inflammatory, autoimmune) •Rheumatic heart disease •Indwelling catheters •IV drug abuse •Chronic alcoholism

Infectious Myocarditis

•Generalized heart muscle weakening •Weakened contraction •Expansion of LV (aneurism) Results can cause arrhythmias, heart failure, the need for heart transplant, or death

chronic phase myocarditis

•Healing with interstitial fibrosis •Ventricle dilation, hypertrophy •Viral RNA persists •DCM (dilated cardiomyopathy - left ventricle enlarged, difficulty pumping) •CHF (congestive heart failure)

General Diagnosis of Myocarditis

•Imaging •CXR- thickened heart walls, cardiomegaly •MRI •Right ventricular endomyocardial biopsy

Etiology of Infectious Myocarditis

•Infections (leading cause) rheumatic fever toxins

Subacute phase myocarditis

•Infiltration of NK cells, macrophage, T cell •Infected cells killed by cytotoxic cells

Etiology of Endocarditis

•Staphylococcus aureus in 28% (more likely acute IE) *#1 if drug use) Viridans group streptococci in 21% (alpha hemolytic, e.g., Streptococcus mutans HACEK Gram-negative organisms

Biomarkers of cardiac injury:

•Troponin I in chronic •Creatine kinase - MK(myokinase) •lactate dehydrogenase •aspartate aminotransferase (AST) •CRP elevated •ESR elevated •Leukocytosis

treatment pericarditis

•Viral- Aspirin or NSAIDS •Bacterial or fungal - Antimicrobials • •Pericardiocentesis - remove fluid; if purulent, it can be cultured. • •Steroids not recommended because they promote recurrence

staph exotoxins

•enterotoxin (ingested, vomiting within 4 hours) •toxic shock syndrome toxin (body rash, fever, lowered blood pressure), •exfoliation toxin (Cleaves desmoglein)

Enterovirus Pathogenesis

•fecal-oral transmission, enteroviruses enter the body and infect the upper respiratory tract, oropharynx, or intestinal mucosa. Can produce a sore throat.

IE Signs & Symptoms

•fever in 83% (usually low grade) •fatigue in 76% •appetite loss in 72% •Splinter hemorrhages •Janeway lesions •Osler's nodes

Acute phase myocarditis

•viremia produced from GI tract, •bind to coxsackie-adenoviral receptor (CAR) in muscle •Focal dying of myocardial cells