{'fraction_non_alphanumeric': 0.044326241134751775, 'fraction_numerical': 0.02009456264775414, 'mean_word_length': 4.719594594594595, '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}}
Holter monitoring in patients with Wolff-Parkinson-White syndrome: with special reference to intermittent pre-excitation.

To characterize the intermittency of pre-excitation in patients with Wolff-Parkinson-White syndrome (W-P-W), we studied the ambulatory electrocardiograms (ECGs) of 48 patients (32 men and 16 women with a mean age of 38.5 years) with W-P-W. As documentation, at least one ECG for each patient had been performed during the follow-up period at our clinics. All cardiovascular drugs were discontinued for at least two days before Holter ECG monitoring. Through a careful beat-to-beat analysis of the QRS complex morphology, we were able to classify these patients into three groups: persistent pre-excitation in 26 (54.2%); intermittent pre-excitation in 17 (35.4%); and no pre-excitation in five (10.4%). There was no significant difference in sex, frequency of arrhythmias or mean heart rate among the three groups. Among the 17 showing intermittent pre-excitation, type A W-P-W was more prevalent (12 cases), and the ratio of pre-excitation to normal beats tended to decrease with age. Conduction normalized gradually with an increase in heart rate in 12 patients and suddenly in five other cases. There were two patients who showed a period of 2:1 pre-excitation intermingled with 1:1 pre-excitation and 1:1 normalized beats. These changes occurred with equal frequency both during the daytime and at night. These findings suggest that intermittent pre-excitation is a rather frequent phenomenon in patients with W-P-W. It occurs more frequently in type A patients and in older patients. Therefore, it may be an intermediate phase between manifest and concealed W-P-W.