Cardiovascular Microbiology Flashcards
Myocarditis can present as a wide array of symptoms with variable presentation. What are some clinical features of myocarditis?
FEVER, precordial discomfort (chest pain), dyspnea, fatigue
Others include unexplained sinus tachycardia, S3 or S4 or summation gallop, abnormal ECG, abnormal echo, new cardiomegaly on CXR, arrhythmia, partial or complete heart block, new-onset BBB, new-onset or worsening heart failure, acute pericarditis, cardiogenic shock, sudden cardiac death, respiratory distress/tachypnea, hepatomegaly
Physical exam findings of myocarditis
Soft S3/S4 (impaired ventricular function), new murmur (secondary to valvular insufficiency), pericardial friction rub (if there is extension into pericardium)
Think systolic CHF — decreased contractility, orthopnea, dyspnea on exertion, crackles, PND
Workup considerations for suspected myocarditis
EKG — assess for arrhythmia (sinus tachycardia most common), transient ST-T wave abnormalities (findings can be nonspecific)
CXR — pt is presenting with CP and/or sx of CHF — must consider all etiologies especially: pulmonary disease, heart failure, dissection. Assess for cardiomegaly
Echocardiogram — assessment of ventricular function and structure; eval of EF, LV size, wall motion abnormalities
PCR — detection of viral genome
Labs — CBC (for leukocytosis), cardiac enzymes (likely elevated secondary to myocyte damage), BNP (heart failure), CPK (muscle damage), ESR and CRP = acute phase reactants
Endomyocardial biopsy can aid in definitive dx
3 major complications of myocarditis
Dilated cardiomyopathy
Myopericarditis (myocarditis extended into pericardium)
Sudden cardiac death (20%)
Tx for myocarditis; how is prognosis determined?
Heart failure therapy, therapy for arrhythmias
Beta blocker, ACEI, diuretics
Avoid NSAIDs, EtOH, and exercise (restricted)
Prognosis is dependent upon clinicopathologic types of myocarditis
Infectious etiologies for myocarditis
Typically Coxsackie B, Trypanosoma cruzi, or Trichinella spiralis
Other considerations: HIV, Chalmydophyla psittaci, Rickettsial sp., Corynebacterium diphtheriae, Neisseria meningitidis, Borrelia burgorferi, Candida
Morphology, transmission, and peak incidence times for coxsackie B virus
+ssRNA virus, small, naked, icosahedral
Transmission = fecal oral
Peak incidence = summer, fall
Clinical manifestations of coxsackie B infection
URI, pleurodynia (“devil’s grip” - severe intercostal pain and fever), myocarditis (most common infectious etiology), aseptic meningitis
Endemic locations and transmission of trypanosoma cruzi (hemoflagellate)
Location: southern US, Mexico, South America
Transmission = reduviid bug, animal carriers
Phases of Chagas dz
Acute: chagoma, romana sign, fever, malaise, LAD, myocarditis, severe meningoencephalitis (usually in younger pts)
Intermediate: asymptomatic
Chronic: dilated cardiomyopathy, arrhythmia, megacolon, achalasia
Diagnostics for chagas dz
Peripheral smear for trypomastigotes, xenodiagnosis
Invasive nematode transmitted via ingestion of cysts from raw pork (boars or horses too)
Trichinella spiralis
Humans are dead-end hosts for trichinella spiralis - describe its lifecycle
Larvae develop in gut —> mate —> larvae disseminate hematogenously —> penetrate muscle tissue
Affect skeletal m, heart, and brain
It is an invasive cycle that can be lethal with heavy infection
Symptoms and diagnostics associated with trichinella spiralis infxn
Abdominal pain, diarrhea, fever (while in small intestine); after muscle invasion get myalgias and other sx based on location
Consider the dx if — periorbital edema, mositis, eosinophilia
Dx: Serologic (ELISA, etc.) or latex agglutination, CPK levels, muscle bx
Infectious agents implicated in pericarditis
Viruses, bacteria, TB (caseating pericarditis), fungi, parasites
Presentation and clinical features for infectious pericarditis
Chest pain — often sharp, positional, and pleuritic in nature, relieved by leaning forwards
Fever
Palpitations
Physical exam findings in infectious pericarditis
Friction rub upon cardiac auscultation, rapid or irregular pulse
What would you see on EKG for infectious pericarditis?
Diffuse ST elevations with reciprocal depressions in leads aVR and V1
PR depression
What would you find on CXR with infectious pericarditis?
Minimal abnormalities in the majority
Exception: pericardial effusion > 250 mL will cause symmetrically enlarged cardiac sillhouette = “water bottle” sign [diaphragm will appear flat to compensate for weight of effusion]
If you suspect infectious pericarditis, what test should you do to assess for pericardial effusion and/or tamponade, as it is more sensitive than a CXR?
Transthoracic echocardiogram
Labs to do when infectious pericarditis suspected
Serial cardiac enzymes CBC with diff ESR CRP Blood cultures if temp >38 C
Major complication of infectious pericarditis
Cardiac tamponade (tx with pericardiocentesis) — counsel about activity restrictions
Tx for infectious pericarditis
High dose ASA TID and colchicine
[ibuprofen, indomethacin options too] — or tx underlying cause!
_______ are CONTRAINDICATED in pericarditis
Anticoagulants
Ziehl Neelson and Auramine-rhodamine stains are used to identify which organism that can potentially cause infectious pericarditis?
Mycobacterium tuberculosis
[Ziehl Neelson is acid-fast stain that shows red rods; Auramine-rhodamine shows apple green color]
Morphology of M.tuberculosis + virulence factors
Acid fast bacillus (weakly G+), obligate aerobes, facultative intracellular (macrophages)
[AFB secondary to mycolic acid cell wall composition — highly resistant to desiccation including NaOH]
Virulence: facultative intracellular, sulfatides, cord factor, surface protein can cause a delayed hypersensitivity and cell mediated immunity reaction (utilized for PPD test), Wax D
The major manifestation of mycobacterium tuberculosis is pulmonary TB, how does it cause a caseating pericarditis?
Through direct lymphatic or hematogenous dissemination of the bacteria
Risk factors for infective endocarditis
Age > 60, M>F
Poor dentition, IV drug abuse, structural heart dz, congenital heart dz, valvular heart dz, prosthetic valve replacement, RHD
IE manifestations can be variable and generally depend on virulence of organism involved. What are some general clinical manifestations seen with IE?
Constituational sx = onset of sx nonspecific in nature then progress toward fever, chills, weight loss, new/worsening murmur, fatigue, arthralgia, and myalgia
Differentiate some clinical manifestations in acute IE vs. subacute IE
Major difference = timeline — acute will have much more rapid onset (<7d)
Acute: rapid progression of sx and cardiac damage; high fever, chills, weakness, SOB, pleuritic CP
Subacute: indolent course; low grade fever, weight loss over time, fatigue, arthralgia/myalgia
Complications of IE
CHF, abscess formation, hematogenous spread, embolism, systemic immune reaction, death