Non-dipping blood pressure variations in adult Kazakhs are derived from decreased daytime physical activity and increased nighttime sympathetic activity

Different Factors Associated with Morning Blood Pressure Surge in Antihypertensive-Naïve Dipper and Non-Dipper Subjects

The relationship between the morning blood pressure surge (MBPS) and cardiovascular risk is inconclusive. Previous studies have not taken into consideration dipping status in examining the MBPS and its associated factors. The aim was to examine factors associated with the MBPS in dippers and non-dippers. The MBPS was calculated by data obtained from ambulatory blood pressure monitoring, using the definition of sleep-trough morning surge. Dipping systolic blood pressure (DipSBP) was defined as [1 - (SBPsleeping/SBPawake)] × 100%. The value in milliseconds of standard deviation of normal-to-normal RR interval after waking up (SDNNaw) was calculated during the 2 h period after waking up. A total of 140 eligible subjects were divided into dippers (n = 62) and non-dippers (n = 78). Multiple regression analysis on data for all subjects revealed different correlations with the MBPS: positive in age, body mass index (BMI), and DipSBP, and inverse in cholesterol/high density lipoprotein-cholesterol (HDL-C) ratio, fasting blood glucose, and 2 h SDNNaw. When dippers were examined separately, age, female gender, and BMI correlated positively with MBPS, while cholesterol/HDL-C ratio and 2 h SDNNaw correlated negatively. For non-dippers, only age was associated with the MBPS. The factors associated with the MBPS were different for dippers and non-dippers. The MBPS seems to be a physiological response in this dipper group because age and BMI correlated positively with the MBPS, while parasympathetic neural activity after waking up and cholesterol/HDL-C ratio showed inverse correlations.

Sleep Rate Mode of Pacemaker-Dependent Patients with Sick Sinus Syndrome Increases Dipper Blood Pressure and Dipper Heart Rate Patterns

Cardiovascular event rates of patients with a dipper blood pressure (BP) and dipper heart rate (HR) pattern are lower than those of patients with nondipper BP and HR patterns. However, how the pacemaker mode affects the diurnal BP and HR patterns remains unclear.We enrolled nine patients (average age 74.4 ± 6.6 years, 4 males and 5 females) with sick sinus syndrome who required atrial pacing. We investigated sequential 6-month pacing regimens (DDD mode at 60 bpm and sleep rate mode). We set the lower rate of sleep rate mode as follows: 60 bpm during the daytime and 50 bpm during the nighttime. The order of pacing mode was randomized, with crossover design. Ambulatory BP monitoring was performed at baseline, 6 months, and 12 months, BP category was classified into four groups (extreme dipper, dipper, nondipper, and riser pattern), and HR was classified into dipper and nondipper patterns.Nighttime HR during the sleep rate mode was significantly lower than that at DDD (57.1 ± 6.2 versus 63.5 ± 3.8 bpm, P = 0.001). The dipper HR pattern was increased in the sleep rate mode compared with those at baseline or DDD mode (versus baseline: 89% versus 44%, P = 0.035; versus DDD: 89% versus 22%, P = 0.004). The dipper BP pattern significantly increased in the sleep rate mode compared with the baseline (56% versus 11%, P = 0.035), but the difference between the sleep rate mode and DDD mode was statistically marginal (56% versus 22%, P = 0.081).The pacemaker settings in the sleep rate mode increased the dipper HR and BP patterns in pacemaker-dependent patients with sick sinus syndrome.

Complexity Change in Cardiovascular Disease

With the fast development of wearable medical device in recent years, it becomes critical to conduct research on continuously measured physiological signals. Entropy is a key metric for quantifying the irregularity and/or complexity contained in human physiological signals. In this review, we focus on exploring how entropy changes in various physiological signals in cardiovascular diseases. Our review concludes that the direction of entropy change relies on the physiological signals under investigation. For heart rate variability and pulse index, the entropy of a healthy person is higher than that of a patient with cardiovascular diseases. For diastolic period variability and diastolic heart sound, the direction of entropy change is reversed. Our conclusion should not only give valuable guidance for further research on the application of entropy in cardiovascular diseases but also provide a foundation for using entropy to analyze the irregularity and/or complexity of physiological signals measured by wearable medical device.

Elevated heart rate and nondipping heart rate as potential targets for melatonin: a review

Elevated heart rate is a risk factor for cardiovascular and all-cause mortalities in the general population and various cardiovascular pathologies. Insufficient heart rate decline during the night, that is, nondipping heart rate, also increases cardiovascular risk. Abnormal heart rate reflects an autonomic nervous system imbalance in terms of relative dominance of sympathetic tone. There are only a few prospective studies concerning the effect of heart rate reduction in coronary heart disease and heart failure. In hypertensive patients, retrospective analyses show no additional benefit of slowing down the heart rate by beta-blockade to blood pressure reduction. Melatonin, a secretory product of the pineal gland, has several attributes, which predict melatonin to be a promising candidate in the struggle against elevated heart rate and its consequences in the hypertensive population. First, melatonin production depends on the sympathetic stimulation of the pineal gland. On the other hand, melatonin inhibits the sympathetic system in several ways representing potentially the counter-regulatory mechanism to normalize excessive sympathetic drive. Second, administration of melatonin reduces heart rate in animals and humans. Third, the chronobiological action of melatonin may normalize the insufficient nocturnal decline of heart rate. Moreover, melatonin reduces the development of endothelial dysfunction and atherosclerosis, which are considered a crucial pathophysiological disorder of increased heart rate and pulsatile blood flow. The antihypertensive and antiremodeling action of melatonin along with its beneficial effects on lipid profile and insulin resistance may be of additional benefit. A clinical trial investigating melatonin actions in hypertensive patients with increased heart rate is warranted.