PubMed · 13993975
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J TRANCHESI. [Electrocardiographical interpretation].. https://pubmed.ncbi.nlm.nih.gov/13993975/
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Intrauterine and neonatal manifestations of congenital long QT syndrome are associated with a high cardiac risk, particularly when atrioventricular block and excessive QT prolongation (> 600 ms(1/2)) are present. In a female newborn with these features, treatment with propranolol and mexiletine led to complete reduction of arrhythmia that was maintained 1.5 years later. High throughput genetic analysis found a sodium channel gene (LQT3) mutation. Disappearance of the 2:1 atrioventricular block and QTc shortening (from 740 ms(1/2) to 480 ms(1/2)), however, was achieved when mexiletine was added to propranolol. This effect was considered to be possibly genotype related. Early onset forms of long QT syndrome may benefit from advanced genotyping.
BACKGROUND: A variety of devices are used to evaluate patients with a potential diagnosis of obstructive sleep apnea (OSA). A committee comprised of members of the American Academy of Sleep Medicine, American Thoracic Society, and American College of Chest Physicians systematically evaluated data on the use of these devices and developed practice parameters. DEVICES REVIEWED: Three categories of portable monitoring (PM) devices were reviewed with regard to assessing the probability of identifying an apnea-hypopnea index (AHI) of greater or less than 15 in attended and unattended settings. Type 2 (minimum of seven channels, including EEG, EOG, chin EMG, ECG or heart rate, airflow, respiratory effort, oxygen saturation), Type 3 (minimum of four channels, including ventilation or airflow (at least two channels of respiratory movement, or respiratory movement and airflow), heart rate or ECG and oxygen saturation) and Type 4 (most monitors of this type measure a single parameter or two parameters) devices were evaluated, and in-laboratory, attended polysomnography was used as a reference. SPECIFIC RECOMMENDATIONS: (1) Insufficient evidence is available to recommend the use of Type 2 PM devices in attended or unattended settings. (2) Type 3 PM devices appear to be capable of being used in an attended setting to increase or to decrease the probability that a patient has an apnea-hypopnea index greater than 15. (3) The use of Type 3 PM devices in an unattended setting is not recommended to rule in, rule out, or both rule in and rule out a diagnosis of OSA. (4) There is some evidence that the use of Type 3 PM devices in an attended in-laboratory setting may be acceptable to both rule in and rule out a diagnosis of OSA if certain limitations are in place. These limitations include manually scoring the records, using the devices only in patients without significant comorbid conditions, having an awareness that symptomatic patients with a negative study should have a Type 1 study, and not using these devices for titrating positive airway pressure or conducting split-night studies. (5) The use of Type 4 PM devices in attended or unattended settings is not recommended. GENERAL RECOMMENDATIONS: Type 3 and 4 PM devices cannot score sleep and, therefore, do not meet some current Medicare guidelines. The use of PM devices is not recommended for general-population screening or in the absence of a pretest probability of the patient having a diagnosis of OSA, for complaints other than those associated with OSA, without review of raw data during interpretation, by physicians without familiarity with their use and limitations, and without trained personnel to perform technical scoring. Future research should address the use of PM devices in patients with comorbid conditions; non-White patients and women; larger, better-controlled studies; studies focused on the use of Type 2 and 3 devices; studies focusing on decision making and outcomes rather than simple classification using arbitrary cutoffs; and studies that seek to elucidate cost-effectiveness data on the use of PM devices.
UNLABELLED: We determined inter- and intra-observer variability of measurements of QT and heart rate corrected QT (QTc) interval in newborn infants. In 55 newborns, a standard 12-lead electrocardiogram (ECG) with rhythm strip was analysed independently by three observers. QT and the preceding RR interval were measured in three different beats. The QTc interval was calculated using the Bazett formula (QTc = QT/ radical RR). Observers repeated their measurements after the recruitment period blinded for their first reading. Inter- and intra-observer variability were determined using the Bland and Altman method. In total, 59 ECGs were recorded. Due to artifacts, six had to be excluded. A marked inter-observer variability was observed in the measurement of the QT and QTc interval. Important intra-observer variability was denoted, with differences up to 80 ms for QTc. CONCLUSION: mainly due to high heart rates, important inter- and intra-observer variability hampers a correct interpretation of the QT interval in newborn infants. We suggest not to rely on one single measurement and to apply different methods of measurement and a margin of safety when interpreting QT and heart rate corrected QT intervals in these age groups for making therapeutic decisions.