I'm Dr. Daisy.
A 20-year-old female college student presented with a 2-week history of fatigue, cough, sinus congestion, and rhinorrhea, followed by 2 days of vomiting, diarrhea, and abdominal pain. The patient's initial symptoms began during her end-of-semester winter examination period; she knew many people who had been ill with similar symptoms, including fatigue and upper respiratory symptoms.
The pulse was 130 beats per minute, and systolic blood pressure ranged from 60 to 70 mm Hg. Emergency medical services were called, and 2 liters of normal saline were administered while the patient was being transported to the emergency department of a local hospital.
Although the patient's initial symptoms appear to have been benign, the hypotension and tachycardia raise the possibility of a more serious process, such as septic shock. Given her history of emesis and the finding of dry mucous membranes on examination, dehydration may be contributing to her rapid pulse and low blood pressure, but it would not explain her hypothermia, which also raises the possibility of sepsis.
An electrocardiogram showed sinus tachycardia, low-voltage, low-anterior forces, flattened T waves, and a mildly prolonged QT interval.
The systolic ejection fraction was 52%, and inferolateral and inferior hypokinesis was detected. Both ventricles appeared unusually thickened and edematous. A small pericardial effusion was seen.
A repeat echocardiogram showed deterioration, with severe, global systolic dysfunction of the left ventricle and an ejection fraction of 24%. There was also evidence of severe diastolic dysfunction and restrictive filling.
On the day after the patient was transferred to the tertiary care center, test results for a nasopharyngeal swab showed positivity for influenza A RNA; that same morning, a swab collected at the initial hospital also showed positive results for influenza A RNA.
Myocarditis is an uncommon complication of influenza, with an overall incidence of up to 11%, although it is unknown whether the incidence varies according to the viral strain.
Myocarditis can be diagnosed with the use of endomyocardial biopsy, but false negative results are common. Since in most human cases and animal models of influenza-associated myocarditis, influenza viral replication has not been confirmed in myocardial tissue, biopsy will rarely prove that influenza is the cause of myocarditis.
Thank you for listening, ciao.