{'fraction_non_alphanumeric': 0.02591283863368669, 'fraction_numerical': 0.004711425206124852, 'mean_word_length': 5.640625, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Congenital long QT syndrome with functionally impaired atrioventricular conduction: successful treatment by mexiletine and propranolol.

Congenital long QT syndrome (LQTS) with atrioventricular block is a rare and malignant arrhythmia, which usually responds poorly to traditional beta-blocker therapy. We describe a male neonate with LQTS with ventricular tachycardia and 2:1 atrioventricular block. This patient's sister had similar presentation and died suddenly at the age of 8 months despite beta-blocker and pacemaker therapy. Our patient responded to a combination of sodium channel blocker (mexiletine) and beta-blocker (propranolol) therapy. He was asymptomatic during a 2-year follow-up period. This case suggests that propranolol combined with mexiletine might be useful in the treatment of patients with LQTS with atrioventricular block.