Diabetic autonomic neuropathy (DAN) commonly complicates diabetes and is associated with increased mortality rates over 5 yr. This fact denotes the significance of DAN prevention, mainly with effective glycemic control. However, total prevention of autonomic neuropathy in diabetic patients is not achievable. Thus, the timely detection of DAN and the use of effective means to improve autonomic nervous system function or slow down its progression become of utmost significance. Heart rate variability (HRV) is a technique that measures the beat-to-beat variability in RR intervals, which reflects changes in autonomic activity and their impact on cardiovascular function. Circadian variation in time and frequency domains of heart variability has been shown to correlate with circadian rhythm of ambulatory ischemia and suggests that relative changes in vagal and sympathetic tone at different times during the day may have a direct relationship to the severity of clinical events. Forty-seven (21 boys and 26 girls) type I insulin-dependent diabetics and 46 control subjects (19 boys and 27 girls) were included in the study. Our investigation demonstrated that overall HRV is markedly depressed in diabetes mellitus (DM). All time domain parameters except standard deviation of all 5-min mean RR intervals and all frequency domain indices maintain significant circadian variation. These changes in overall HRV and HRV circadian rhythms reflect significant reductions in cardiac parasympathetic activity and, possibly, increased sympathetic tone.

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Objective: The objective of this study is to investigate endothelial dysfunction (ED) and arterial stiffness (AS) and determine the association with diastolic dysfunction in children with type 1 diabetes mellitus (DM). Methods: A total of 42 patients without diabetic complications (mean age: 13.21 years) and 40 healthy (mean age: 13.07 years) children were included in this study. AS was assessed with ascending aorta M-mode measurements, diastolic dysfunction with pulsed wave (PW) Doppler and tissue Doppler echocardiography measurements and flow-mediated dilatation (FMD) and carotid intima-media thickness (CIMT) with high-resolution ultrasonography. Results: Results of diabetic group and healthy children were compared. In diabetic group, aortic strain (8.40 ± 2.98, 20.12 ± 5.04; p < 0.001), aortic distensibility (7.36 ± 2.92, 16.59 ± 4.25; p < 0.001) and FMD% (7.70 ± 2.83, 11.33 ± 2.85; p < 0.001) were found decreased, and CIMT (0.52 ± 0.09 mm, 0.47 ± 0.08 mm; p < 0.05) was found increased. Additionally, left ventricular lateral segment and right ventricular free-wall isovolumic relaxation time (IVRT) and myocardial performance index (MPI) were found increased. Correlation analyses demonstrated a negative correlation between FMD and IVRT and MPI. Conclusions: ED and AS were found in type 1 DM patients without diabetic complications. Additionally, correlation was shown between increased AS and ED and right and left ventricular diastolic dysfunctions.

We aimed to assess early-onset chronic progressive cardiotoxicity in the left and right ventricles with increasing cumulative anthracycline doses. We evaluated 72 patients within the first year after doxorubicin and/or daunorubicin treatment (median 1.3 months; range 0.3-11.5) and 31 healthy controls. Pretreatment and posttreatment QT interval analyzes were performed in 27 newly diagnosed patients. The echocardiographic data of all examinations of 72 patients were classified into three groups according to instant cumulative anthracycline doses: treatment group (TG)-I (≤120 mg/m(2); n = 26), TG-II (120-240 mg/m(2); n = 39), and TG-III (≥240 mg/m(2); n = 40). Diastolic and systolic parameters were analyzed by conventional echocardiography and tissue Doppler imaging (TDI) and compared with those of healthy controls. The mean age for patients and controls was 8.2 ± 4.5 and 9.6 ± 4.2 years, respectively (p > 0.05). QTc dispersion significantly increased after anthracycline treatment (p = 0.02). TDI showed decreased E' velocity (p < 0.001) and E'/A' ratio (p < 0.001) at lateral tricuspid annulus segment in TG-I, and these findings continued in TG-II and -III. In addition, S' velocity decreased in TG-I, -II, and -III at lateral mitral annulus (10.5 ± 2.6 cm/s, p < 0.05; 9.9 ± 2.2 cm/s, p < 0.001; and 10.1 ± 2.3 cm/s, p < 0.01, respectively). However, decrease in left-ventricular ejection fraction was statistically significant in TG-II and -III (p < 0.001). Although myocardial performance index was significantly increased in all treatment groups in both segments, it was primarily due to significant increases in isovolumic relaxation time at the lateral tricuspid annulus and isovolumic contraction time at the lateral mitral annulus. Abnormalities in diastolic function in right ventricle and systolic function in the left ventricle were observed even with a cumulative anthracycline dose <120 mg/m(2) by TDI. In addition, anthracycline treatment led to an increase in QTc dispersion.

Cardiac dysfunction, including congestive heart failure and fatal arrhythmia, is a frequent cause of death among children with thalassemia major (TM). Autonomic nervous system activity typically is measured by a series of cardiovascular autonomic function tests, but these tests are unsuitable for young patients because they are invasive or complex. Heart rate variability assessment is a technique that measures the beat-to-beat variability in R-R intervals. This variability reflects changes in autonomic activity and their impact on cardiovascular function. This study examined 32 patients with TM to evaluate heart rate variability (HRV) in a preclinical phase of cardiac involvement. The study patients showed no evidence of heart failure or signs of peripheral or autonomic neuropathy. All HRV parameters were significantly reduced in the TM patient group compared with the control group. The results of this study can be interpreted as evidence of early cardiac autonomic neuropathy in young thalassemic patients. Therefore, all TM patients should be screened using HRV analysis for that complication.