Behavior of Blood Pressure Variables in Children and Adolescents with Duchenne Muscular Dystrophy

Abstract Background: Duchenne muscular dystrophy is an X-chromosome-linked genetic disorder (locus Xp21). Involvement of the cardiovascular system is characterized by fibrous degeneration/replacement of myocytes with consequent ventricular hypertrophy and arterial hypertension. Objective: To assess, by using 24-hour ambulatory blood pressure monitoring, the behavior of blood pressure variables in children and adolescents with a confirmed diagnosis of Duchenne muscular dystrophy. Methods: Prospective observational cohort study, which selected 46 patients followed up on an outpatient basis, divided according to age groups. Blood pressure was classified according to the age percentile. The monitoring interpretation includes systolic and diastolic blood pressure means, systolic and diastolic blood pressure loads, and nocturnal dipping. The blood pressure means were calculated for the 24-hour, wakefulness and sleep periods. Nocturnal dipping was defined as a drop in blood pressure means during sleep greater than 10%. The significance level adopted was p < 0.05. Results: Nocturnal dipping for systolic blood pressure was present in 29.9% of the participants. Approximately 53% of them had attenuated nocturnal dipping, and 15%, reverse nocturnal dipping. The age groups of 9-11 years and 6-8 years had the greatest percentage of attenuation, 19.1% and 14.9%, respectively. Regarding diastolic blood pressure, nocturnal dipping was identified in 53.2% of the children, being extreme in 27.7% of those in the age group of 6-11 years. Conclusions: The early diagnosis of blood pressure changes can allow the appropriate and specific therapy, aimed at increasing the life expectancy of patients with Duchenne muscular dystrophy.

摘要 背景：杜氏肌营养不良症（Duchenne muscular dystrophy，DMD）是一种X连锁遗传性疾病，致病位点为Xp21。该疾病累及心血管系统时，以心肌细胞纤维变性/替代为特征，进而引发心室肥厚与动脉高血压。
研究目的：通过24小时动态血压监测（24-hour ambulatory blood pressure monitoring），评估确诊杜氏肌营养不良症的儿童及青少年群体的血压变量变化特征。
研究方法：本研究为前瞻性观察队列研究，纳入46名门诊随访患者并按年龄分组。血压分级依据年龄百分位数进行划分。动态血压监测指标包括收缩压、舒张压均值，收缩压、舒张压负荷值，以及夜间血压下降率（nocturnal dipping）。分别计算24小时、清醒时段与睡眠时段的血压均值。夜间血压下降率定义为睡眠时段血压均值较清醒时段下降幅度超过10%。本研究采用的显著性检验水准为p<0.05。
研究结果：收缩压夜间血压下降率正常的参与者占比为29.9%。约53%的参与者存在夜间血压下降率减弱，另有15%存在夜间血压下降率逆转。9~11岁与6~8岁年龄组的夜间血压下降率减弱占比最高，分别为19.1%与14.9%。就舒张压而言，53.2%的患儿存在夜间血压下降率正常，其中6~11岁年龄组中有27.7%存在夜间血压过度下降。
研究结论：早期诊断血压变化可指导制定恰当的针对性治疗方案，以期延长杜氏肌营养不良症患者的预期寿命。