Diphtheritic Myocarditis

Diphtheritic myocarditis is a complication of C. diphtheriae respiratory infection, characterized by pharyngotonsillitis/laryngitis with gray-white pseudomembrane and toxic systemic symptoms; myocarditis is the most serious complication and leading cause of death. Pathologically it shows myocardial hyaline degeneration or necrosis with scant cell infiltration; 10-25% of diphtheria patients have cardiac involvement, ~50% of deaths.

Common Symptoms

Dyspnea; airway obstruction; abdominal pain; fatigue; cyanosis; nausea

Causes and Pathogenesis

(1) Etiology: acute infection with C. diphtheriae transmitted by contact with patients/carriers, usually confined to the upper respiratory tract forming a tough adherent pseudomembrane that bleeds when torn; it starts on one tonsil and may spread to the other tonsil, uvula, soft palate, pharyngeal wall, larynx, trachea, and bronchi causing obstruction and death from hypoxia. Cutaneous diphtheria occasionally affects eyes, middle ear, buccal mucosa, and genitalia. Systemic effects are mainly myocarditis and peripheral neuritis due to exotoxin. (2) Pathogenesis: toxin inhibits amino-acid transfer from soluble RNA to polypeptide chains, blocking protein synthesis. C. diphtheriae has weak invasiveness but its exotoxin is highly toxic; after absorption it causes toxemia with systemic changes (heart, adrenal, peripheral nerves). Early pathology shows cardiac dilation, cloudy swelling, fatty change, then multifocal hyaline/granular degeneration and myocardial necrosis with polymorphonuclear infiltration; late fibrosis and conduction system degeneration/necrosis/scarring. Cardiac involvement appears at the end of week 1/early week 2; recovery (granulation, fibrosis) by weeks 3-4.

Treatment

Drug therapy, supportive therapy

Preventive Measures

1. Protect susceptibles and control sources: isolate/treat patients until symptoms resolve and two nasopharyngeal cultures are negative. 2. Cut transmission. 3. Boost immunity with DPT or adsorbed purified diphtheria toxoid.

Department to Visit

It is recommended to visit the Cardiology department; an appointment can be booked on this platform before the visit.

Warm reminder: The above information is for health science reference only and cannot replace professional medical diagnosis. If you have related symptoms, please seek medical attention at a regular hospital promptly.