A case of Mitral Honk

A 5-year-old girl complained of a sound coming from the left side of her chest for the previous two years, which occurred intermittently, for minutes to hours, for 3-7 consecutive days, usually during mild viral infections, without any other associated symptoms.

Her physical exam was unremarkable and her previous cardiac ultrasound report revealed only a mild mitral valve prolapse with minimal regurgitation. Other investigation like Chest x-ray, bronchoscopy, and blood tests were unremarkable.

An intermittent high-pitched sound, repeating at a frequency of approximately 90 times per minute was audible, that ruled out a respiratory cause due to the frequency of the sound. Cardiac conditions like prosthetic mechanical valve and pneumomediastinum-associated Hamman sign was suspected as they produce room-audible sounds. The patient's history ruled out the former condition, while the recurrence, absence of other signs, and normal chest x-ray ruled out the latter diagnosis. Hence, a "mitral honk" was doubted. 

On the next occurrence of symptoms, a second cardiac ultrasound was conducted that ceased shortly, however the sound was detectable with a phonendoscope. Doppler evaluation and cardiac auscultation recognized the sound source as mitral valve with elongation of chordae tendineae. Six months follow-up, the mitral honk remained occasionally present, without any other symptoms. 

At the annual follow-up, an ultrasound and 24-hour electrocardiogram were scheduled. 

Hence, in the case of a loud thoracic sound in children, without any associated symptoms a mitral honk should be suspected, which depicts a typical sound, and should be confirmed with an ultrasound. Physicians must avoid useless and invasive investigations for such conditions. 

Sutera M. et al. A Strange Noise Coming from Her Chest: A Mitral Honk. J Pediatr 2024;274:114185