Fractal correlation property of heart rate variability in response to the postural change maneuver in healthy women.

BACKGROUND: We evaluated the effects of the PCM on the fractal analysis of the HRV in healthy women. METHOD: We evaluated healthy women between 18 and 30 years old. HRV was analyzed in the time (SDNN, RMSSD, NN50 and pNN50) and frequency (LF, HF and LF/HF ratio) domains as well as short and long-term fractal exponents (alpha-1 and alpha-2) of the detrended fluctuation analysis (DFA). HRV was recorded at rest for ten minutes at seated rest and then the women quickly stood up from a seated position in up to three seconds and remained standing for 15 minutes. HRV was recorded at the following time: rest, 0-5 min, 5-10 min and 10-15 min during standing. RESULTS: We observed decrease (p < 0.05) in the time-domain indices of HRV between seated and 10-15 minutes after the volunteer stood up. The LF (ms(2)) and HF (ms(2)) indices were also reduced (p < 0.05) at 10-15 minutes after the volunteer stood up compared to seated while the LF (nu) was increased at 5-10 min and 10-15 min (p < 0.05). The short-term alpha-1 exponent was increased (p < 0.05) at all moments investigated compared to seated. Increase in the properties of short-term fractal correlations of heart rate dynamics accompanied by a decrease in the parasympathetic modulation and global HRV was observed in response to the postural change maneuver. CONCLUSION: We suggest that fractal analysis of HRV is more sensitive than frequency and time-domain analysis of HRV during the postural change maneuver.

An experience of vascular access for hemodialysis in Brazil.

BACKGROUND: The analysis of hemodialysis services is relevant for the quality of life of patient. In this study we investigated the profile of vascular access used for hemodialysis patients in our Unit. METHODS: We evaluated 219 patients of both genders aged over 18 years old who have undergone implant or manufacture of vascular hemodialysis access. We excluded patients on renal replacement therapy by peritoneal dialysis. RESULTS: Associated diseases were hypertension and diabetes mellitus. 161 had arteriovenous fistula, with 153 held by the same dialysis and nine of them were still maturing. 27 patients on dialysis used central venous catheter. 148 were indigenous and five were made using polytetrafluoroethylene prosthesis (PTFE). Among the 27 patients with central venous catheters, ten used short-term catheter and 17 used long-term catheter. The most frequent type of fistula use was on the radio distal cephalic, in 85 patients (52.5%), followed by radio cephalic proximal in 26 patients (16%). The number of fistulas in dialysis patients conducted by this kind of therapy ranged from one to ten and in 64 patients (41.83%) fistula was the first and only to be made. Among the fistula for dialysis patients, the highest prevalence was radio cephalic fistula in 111 patients (72.5%) and mean duration of use was 48.1 months, ranging from two months to 17 years. CONCLUSION: Our Unit of hemodialysis is above the limits established by international norms.

Memantine effects on liver and adrenal gland of rats exposed to cold stress.

BACKGROUND: Memantine attenuates heart stress due cold stress, however, no study focused its effects on liver and adrenal gland. We evaluated its effects on lipid depletion in adrenal gland and glycogen depletion in liver of rats exposed to cold stress. METHODS: Male rats divided into 4 groups: 1)Control (CON); 2)Memantine (MEM); 3)Induced cold stress (IH) and; 4)Induced cold stress memantine (IHF). Memantine were administrated by gavage (20 mg/kg/day) during eight days. Cold stress were performed during 4 hours once at - 8°C. Lipid and glycogen depletion were presented as its intensity levels. RESULTS: Rats exposed to cold stress presented the highest glycogen (p < 0.001) and lipid depletion (p < 0.001) in liver and adrenal gland, respectively. We noted that memantine significantly reduced lipid depletion in adrenal gland and glycogen depletion in liver. CONCLUSION: Memantine prevented glycogen depletion in liver and lipid depletion in adrenal gland of rats under a cold stress condition.

Sudden cardiac death athletes: a systematic review.

Previous events evidence that sudden cardiac death (SCD) in athletes is still a reality and it keeps challenging cardiologists. Considering the importance of SCD in athletes and the requisite for an update of this matter, we endeavored to describe SCD in athletes. The Medline (via PubMed) and SciELO databases were searched using the subject keywords "sudden death, athletes and mortality". The incidence of SCD is expected at one case for each 200,000 young athletes per year. Overall it is resulted of complex dealings of factors such as arrhythmogenic substrate, regulator and triggers factors. In great part of deaths caused by heart disease in athletes younger than 35 years old investigations evidence cardiac congenital abnormalities. Athletes above 35 years old possibly die due to impairments of coronary heart disease, frequently caused by atherosclerosis. Myocardial ischemia and myocardial infarction are responsible for the most cases of SCD above this age (80%). Pre-participatory athletes' evaluation helps to recognize situations that may put the athlete's life in risk including cardiovascular diseases. In summary, cardiologic examinations of athletes' pre-competition routine is an important way to minimize the risk of SCD.

Cardiac baroreflex is already blunted in eight weeks old spontaneously hypertensive rats.

BACKGROUND: The literature did not evidence yet with which age spontaneously hypertensive rats (SHR) start to present baroreflex reduction. We endeavored to evaluate the baroreflex function in eight-week-old SHR. METHODS: Male Wistar Kyoto (WKY) normotensive rats and SHR aged eight weeks were studied. Baroreflex was calculated as the variation of heart rate (HR) divided by the mean arterial pressure (MAP) variation (DeltaHR/DeltaMAP) tested with a depressor dose of sodium nitroprusside (SNP, 50 microg/kg) and with a pressor dose of phenylephrine (PHE, 8 microg/kg) in the right femoral venous approach through an inserted cannula in the animals. Significant differences for p < 0.05. RESULTS: Baseline MAP (p < 0.0001) and HR (p = 0.0028) was higher in SHR. Bradycardic peak was attenuated in SHR (p < 0.0001), baroreflex gain tested with PHE was also reduced in the SHR group (p = 0.0012). PHE-induced increase in MAP was increased in WKY compared to SHR (p = 0.039). Bradycardic reflex responses to intravenous PHE was decreased in SHR (p < 0.0001). CONCLUSION: Eight weeks old SHR already presents impairment of the parasympathetic component of baroreflex.