Complete heart block in a boy with hyperostosis-hyperphospha
Hyperostosis–hyperphosphataemia syndrome (HHS) is a rare metabolic disorder characterized by recurrent painful swelling of long bones and periosteal new bone formation. The present case has been reported in the European Heart Journal - Case Reports.

A 6-year-old boy was referred for bradycardia. He was diagnosed with HHS 3 years’ prior, after investigation for the cause of joint pain and genu valgum.

During medical follow-up in 2013-16, the paediatric cardiologist discovered thickened and calcified mitral and aortic valves and progression of cardiac conduction disturbance from 1st degree to 3rd degree atrioventricular block (AVB). The patient died in 2017 due to multiorgan failure caused by hyperphosphataemia and ectopic calcification.

Learning points
• This case report highlights the first reported atrioventricular block due to phosphate deposition among patients affected with hyperostosis–hyperphosphataemia syndrome.

• Although some patients with this syndrome may survive to adulthood, but severe forms may not survive in childhood due to the severity of cardiac involvement.

Read in detail about the case here: