Abstract
Background: Atrioventricular block (AVB) in young adults is rare, and the etiologies and mechanisms in most cases remain uncertain. Alport syndrome is a heterogeneous, hereditary disorder characterized by nephropathy, hearing loss, and ocular abnormalities. Complete AVB has never been reported in Alport syndrome patients with normal kidney function. Case report: A 20-year-old male patient was admitted to hospital with “asymptomatic bradycardia for years”. On admission, the patient’s blood pressure was normal and electrocardiogram (ECG) showed third-degree AVB with atrial rate of 63 bpm and ventricular rate of 36 bpm. He was diagnosed with Alport syndrome at the age of 10. Genetic testing at that time showed single nucleotide variants (c.2372T>C, c.2072T>G) and deletion (c.1781-1949(Exon25)) in COL4A5 gene. During the subsequent 10-year follow-up, the patient was presented with consistent hematuria and proteinuria, but his renal function has never been found impaired. He denied other medical history as well as family history of arrhythmia. Laboratory tests indicated hypoproteinemia, hyperuricemia, hyperlipidemia, and hyperhomocysteinemia. The 24-hour ambulatory ECG revealed a heart rhythm consisting of sinus rhythm with second-degree AVB (2:1 downward transmission) and complete AVB with junctional escape. The mean ventricular rate was 36 bpm (ranged 25-60 bpm). Neither echocardiography nor cardiac magnetic imaging with delayed gadolinium enhancement found any significant abnormality. We then did whole exome sequencing (WES), which did not identify specific pathogenic variant (Table1). 3mg atropine was admitted to the patient for an atropine test to rule out the possibility of vagally mediated AVB and the pacemaker implantation was then performed. Conclusion: We report a case of complete AVB with unknown etiology in a young patient with Alport syndrome.
Published Version
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