Test on Myocarditis: Etiology, Diagnosis, and Therapy

Question 1: Is it true that bacterial infections are the most commonly associated infective agents causing myocarditis?

A. Ano

B. Ne

Explanation: The study materials state that myocarditis has been reported with almost all types of infective agents but is most commonly associated with viruses and the protozoan Trypanosoma cruzi, not bacterial infections.

Question 2: Which of the following statements about bacterial myocarditis caused by Diphtheria or Clostridial infection is accurate according to the study materials?

A. Clostridial infections rarely cause myocardial damage, but often lead to severe pericarditis.

B. Cardiac involvement in diphtheria is common, occurring in almost half of cases, and is the leading cause of death for patients with this infection.

C. The diphtheria bacillus primarily causes myocardial injury through direct cellular invasion, rather than toxin release.

D. Treatment for diphtheria-related cardiac involvement prioritizes antibiotics, with antitoxin administered only if antibiotics are ineffective.

Explanation: The study materials state that diphtheria specifically affects the heart in almost one-half of cases, and cardiac involvement is the most common cause of death. They also mention that the bacillus releases a toxin that impairs protein synthesis and may particularly affect the conduction system, and that the specific antitoxin should be administered as soon as possible, with higher priority than antibiotic therapy. For clostridial infections, the materials note that clostridial toxin causes myocardial damage and gas bubbles can be detected in the myocardium, with occasional abscess formation in the myocardium and pericardium, refuting the claim that it rarely causes myocardial damage or primarily causes pericarditis.

Question 3: The study materials indicate that involvement of the heart with hepatitis B is a common occurrence in patients with myocarditis.

A. Ano

B. Ne

Explanation: The study materials state that 'Involvement of the heart with hepatitis B is uncommon but can be seen when associated with systemic vasculitis (polyarteritis nodosa).'

Question 4: According to the study materials, which of the following are included in the initial or further laboratory evaluation for suspected myocarditis?

A. Serum levels of troponin and creatine phosphokinase

B. Magnetic resonance imaging (MRI)

C. Endomyocardial biopsy

D. Detection of viral genomes using Polymerase chain reaction (PCR) in blood

Explanation: The study materials state that the initial evaluation includes serum levels of troponin and creatine phosphokinase, and magnetic resonance imaging (MRI) is increasingly used for diagnosis. Endomyocardial biopsy is indicated in specific cases of new heart failure with conduction blocks or ventricular tachyarrhythmias. While PCR detects viral genomes, the materials do not list it as part of the *laboratory evaluation for suspected myocarditis* but rather discuss its use in detecting viral genomes in DCM patients and control hearts, without explicitly stating it's an evaluation step for *suspected myocarditis*.

Question 5: Conduction system abnormalities, including sinus node and AV node dysfunction, are typical features of chronic Chagas' disease.

A. Ano

B. Ne

Explanation: Features typical of Chagas' disease are conduction system abnormalities, particularly sinus node and AV node dysfunction and right bundle branch block.