The muscle strength reduction in Marfan patients was not fully explained by a decrease in lean leg mass, suggesting qualitative skeletal-muscle alterations related to abnormal fibrillin expression in muscle connective tissue.

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In normal subjects, the level and variability of blood pressure decrease during non-rapid eye movement (non-REM) sleep. In contrast, sleep apnea is associated with large swings in nocturnal pressure. In this study, we evaluated a computer-derived index of all-night blood pressure variability in normotensive snorers with or without sleep apnea. We also examined this index in snorers receiving medical treatment for coexistent ischemic heart disease. Beat-to-beat blood pressure was recorded with a photoplethysmographic device (Finapres) throughout polysomnography. Subjects were categorized into four groups: those without cardiovascular disease without or with sleep apnea (> or = 15 apnea plus hypopnea per hour of sleep), and those with ischemic heart disease without or with sleep apnea. A frequency distribution histogram of all increases and decreases of blood pressure according to their amplitudes was drawn and the SD of the distribution used as an estimation of variability. Mean systolic and diastolic pressures during the total sleep time were not different among the four groups. In contrast, the SD of the distribution of systolic and diastolic pressure variations that were higher in the apneic than in the nonapneic groups (P < .05) correlated with apnea plus hypopnea (P < .0001) and transient electroencephalographic arousal number per hour of sleep (P < .0001). In both apneic and nonapneic subjects, blood pressure variability as assessed by SD decreased during stages 3 and 4 of non-REM sleep compared with stages 1 and 2 and REM sleep (P < .001). Blood pressure variability was similarly increased in apneic subjects with or without ischemic heart disease. We speculate that in apneic individuals with coexistent ischemic heart disease, pressure variability that is increased despite treatment with beta-blockers or calcium antagonists may be a risk factor for acute coronary events.

Obstructive sleep apnoea syndrome (OSAS) induces marked haemodynamic fluctuations during sleep that might be deleterious to the cardiovascular system. The influence of daytime blood pressure (BP) levels and aging on short-term BP variability during sleep in OSAS patients was investigated.Twenty-nine subjects with newly-diagnosed untreated OSAS were categorised into three groups: normotensive subjects aged v50 yrs (n=10); subjects aged v50 yrs with untreated hypertension (n=8); and normotensive subjects aged w50 yrs (n=11). Beat-bybeat BP was recorded with a Finapres device during polysomnography. The average values ¡ SD of apnoea-related BP elevations and the values of the frequency distribution of all BP variations during sleep were assessed to estimate short-term BP variability.Apnoea-related systolic (or diastolic) BP elevations were significantly greater in hypertensives than in normotensives agedv50 yrs (50.3¡4.88 versus 30.7¡2.14 mmHg, pv0.001), as was the SD of systolic (or diastolic) BP variations during sleep (I9.6¡2.22 versus 11.1¡0.73, pv0.001). Short-term BP variability was not significantly increased in normotensive elderly patients.To conclude, the results suggested that systemic hypertension is associated with a greater exacerbation of short-term variability during sleep in obstructive sleep apnoea syndrome patients. Systemic hypertension (HT) is highly prevalent in patients with obstructive sleep apnoea syndrome (OSAS) [1], and recent epidemiological studies [2][3][4] suggest that this association is not entirely explained by known confounding factors such as obesity, age and sex. It has been speculated that the cardiovascular morbidity of OSAS may, in part, be related to the oscillations in systemic blood pressure (BP) and increases in sympathetic discharges that occur repeatedly during the night [5,6]. Indeed, BP falls in time with inspiratory efforts at the beginning of each obstructive episode and rises abruptly at apnoea termination, reaching a peak during the first postapnoeic breaths. Moreover, whereas in normal subjects sympathetic activity decreases during the night, measurements with microneurographical techniques have shown a progressive increase in sympathetic nerve activity during obstructive apnoea with a peak near the end of apnoea [5,7]. Consequently, the significant decrease in the level and variability of BP normally observed during nonrapid eye movement (NREM) sleep is blunted in OSAS patients [7].In subjects with untreated essential HT, arterial baroreceptor reflex operates at higher pressures and baroreceptor heart-rate reflex has been reported to be decreased [8]. The resulting increase in short-term variability of BP may play a role in the alteration of function and structure of the cardiovascular system, since in subjects with untreated systemic HT, targetorgan damage has been shown to be related not only to the level of 24-h mean intraarterial BP, but also to BP variability [9,10]. As nocturnal BP variability has been reported to be increased in patients with es...