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PubMed2003

[Literature review of the latest research results concerning the positive effect of exercise therapy in chronic heart insufficiency].

Scientific investigations indicate similarities in the pathophysiology of heart insufficiency and that of physical inactivity: similar changes in peripheral hemodynamics (increased peripheral vascular resistance, worsening of oxygen utilization during exercise), in autonomic control (activation of neurohumoral compensatory mechanisms, e.g. the renin-angiotensin system, overactivation of the sympathicus, reduction of vagal tonus, reduced pressosensitivity), in functional activity (reduced exercise tolerance and reduced maximum oxygen uptake), in skeletal muscle (decrease in mass, changes in structure), and in the psychological state (reduction in activity and feeling of well-being). In several, although small-scale studies it could be shown that patients with advanced left ventricular failure were able to take part in training programs without experiencing any ill effects, and that there was a positive shift in the usual typical effects of physical training, such as increase of heart rate, change in respiratory frequency, and maximum oxygen uptake. It could be shown that exercise therapy can result in a shift in the balance between the sympathetic and the parasympathetic tonus in the low- and high-frequency maxima of the R-R interval variability. The pre-training general predominance of the sympathetic tonus over the vagal tonus was changed dramatically by the training, leading to a predominance of the vagal tonus. Recent controlled studies with a randomized and controlled cross-over design and the application of a training program which was carried out regularly and independently have confirmed the positive effect of aerobic fitness training in cases of heart disease. At the end of the exercise phase, the patients experienced a significant improvement of the symptoms of left ventricular failure and of their capacity for exercise; furthermore, the training altered parts of the neurohumoral activation, which count as the main factors in the progression and death rate of patients with chronic cardiac disease.

Exercise Test↗
PubMed1996

Reduced heart rate variability after right-sided stroke.

BACKGROUND AND PURPOSE: Recently, asymmetries have been demonstrated in skin sudomotor and vasomotor function after unilateral cerebral lesions. The present study was performed to determine whether other bedside tests reflecting sympathetic and parasympathetic cardiovascular functions would reveal differences with respect to the side of cerebrovascular lesions. METHODS: Heart rate variability during deep breathing as well as blood pressure and heart rate changes during tilt and isometric handgrip was measured in a group of patients with a monofocal stroke and compared with similar data from age-matched patients with transient ischemic attack and healthy control subjects. RESULTS: Compared with left-sided stroke and with the control subjects, stroke location on the right side was associated with a reduced respiratory heart rate variability (P > .01), a reflex mainly under parasympathetic control. In contrast, reflexes mainly reflecting peripheral sympathetic function were equal for right- and left-sided lesions. CONCLUSIONS: Since an imbalance in cardiac autonomic innervation may be crucial for the generation of cardiac arrhythmias and since reduced heart rate variability has been associated with increased mortality, the findings suggest that the risk of sudden death may be correlated with lateralization and location of the brain infarct after stroke.

Analysis of Variance↗
PubMedDate not supplied

AV fistula rates: changing the culture of vascular access.

PURPOSE: Data from the United States Renal Data System show about 30% of prevailing hemodialysis (HD) patients use arteriovenous fistulae (AVF), which falls far short of the Kidney Disease Outcomes Quality Initiative (K/DOQI) goals of 40-50%. Recent initiatives to increase the use of AVF in HD patients have been criticized as unachievable under realistic practice conditions. METHODS: A multidisciplinary effort to increase AVF use was undertaken at an outpatient HD center beginning in 1998. Strategies focused on education and recruitment of patients in both inpatient and outpatient settings, preservation of veins, pre-operative vein mapping, and education of staff. RESULTS: AVF rates increased from 32%, to 72% over 6 years. The percentage of prosthetic grafts decreased from 40% to 13%. Central venous catheters fell from 28% to 15%. Among residual patients with catheters, 77% had maturing fistulae, as well. Infection rates in the dialysis unit decreased by 39%. Bacteremia declined by 47%. These improvements have been sustainable over the past 12 months. CONCLUSIONS: Adherence to a strategic program similar to the Fistula First Initiative can increase fistula rates under ordinary practice conditions. High fistula rates can be achieved in male and female patients. Unanimous commitment among all members of the health care team is needed. Reduction in the risks of infection, bacteremia, endocarditis, and death may be derived from achievable changes in practice.

Journal Article↗
PubMed1992

Dynamic analysis of cardiac R-R intervals in normal infants and in infants who subsequently succumbed to the sudden infant death syndrome.

Infants who subsequently succumb to the sudden infant death syndrome (SIDS) have higher heart rates and reduced heart rate variation compared with other infants. We examined dynamic changes in cardiac interbeat intervals to explore these differences in cardiac control. Recordings of electrocardiographic activity and respiratory movement were acquired from 13 SIDS victims before their deaths. Moment-to-moment changes in R-R intervals during quiet sleep, rapid eye movement sleep, and waking were compared with values of 13 matched control infants. For each sleep-waking state, every R-R interval was plotted against the previous interval (Poincaré plots), and each change in interbeat interval was plotted against the previous change. Dispersion of interbeat intervals at different heart rates was reduced in SIDS victims, resulting in Poincaré plots markedly different from those of controls. The dispersion, sampled at the 10th and 90th percentiles of heart rates, was reduced across all sleep-waking states in SIDS victims. At high heart rates, the difference between groups disappeared after correcting for basal rate; however, the reduced range at low heart rates was independent of basal rate. SIDS victims also showed smaller beat-to-beat changes in heart rate and fewer sustained runs of consistent heart rate changes during waking relative to controls. The differences in cardiac rate dynamics suggest altered autonomic control in infants who succumb to SIDS. We speculate that the autonomic disturbance may lead to cardiac instability or may indicate CNS alterations with the potential to affect other vital functions.

Autonomic Nervous System↗
PubMed2002

Delayed childbearing and its impact on population rate changes in lower birth weight, multiple birth, and preterm delivery.

OBJECTIVE: This study quantified the impact of delayed childbearing (maternal age greater-than-or-equal to 35 years) on population rate changes in low birth weight (LBW; < 2500 g), preterm delivery (< 37 weeks), multiple births, and small for gestational age (SGA; < 10th percentile) in Alberta, Canada, between 1990 (N = 42 930) and 1996 (N = 37 710). METHODS: Data were obtained from the provincial notification of a live or stillbirth. Analyses included relative risk estimates and chi(2) tests for trend. Potential confounding attributable to in vitro fertilization was investigated. RESULTS: The proportion of births to women greater-than-or-equal to 35 years of age was 8.4% in 1990 and 12.6% in 1996, a 51.2% increase. Among these women, LBW delivery increased 11%, and preterm delivery increased 14%. Delayed childbearing accounted for 78% of the change in LBW rate in the population and 36% of the change in preterm delivery rate in the population. Provincial multiple birth rates increased by 15% for twins and 14% for triplets. Delayed childbearing accounted for 15% of the twin increase and 69% of the triplet increase. When in vitro fertilization pregnancies were excluded, the change was 43% for preterm rates, 100% for LBW, 14% for twins, and 9% for triplets. Delayed childbearing did not contribute to changes in singleton SGA deliveries. CONCLUSIONS: The findings suggest that the recent increase in LBW and preterm delivery is partly related to the population phenomenon of delayed childbearing. Maternal age was not related to changes in SGA, suggesting that the age effect is through pregnancy complications that lead to preterm delivery and LBW. Prospective parents should be informed about the higher risk for neonatal morbidity associated with delayed childbearing. Health care providers should be aware of the impact of delayed childbearing on health care resources.

Adult↗
PubMed1991

Circadian variation of myocardial ischemia in patients with stable coronary artery disease.

The circadian variation of myocardial ischemia detected during 24-h ambulatory electrocardiographic monitoring (AEM) was analyzed in 123 patients with stable angina pectoris, positive exercise test, and angiographically proven coronary artery disease. A total of 437 ischemic episodes (ST-segment depression greater than or equal to 1 mm and duration greater than or equal to 1 min) were observed; 333 (76%) episodes remained asymptomatic, and only 104 (24%) episodes were accompanied by anginal pain. Ischemic episodes predominantly occurred during the morning hours, between 6 a.m. and noon, and another smaller peak was observed in the afternoon, between 4 and 5 p.m.; this diurnal pattern was influenced neither by the extent of coronary artery disease nor the degree of left ventricular dysfunction. The circadian variation was restricted to the 345 (78%) ischemic episodes preceded by increases in heart rate; the 92 (22%) episodes without prior heart rate changes occurred randomly throughout the day. The morning peak in ischemic episodes was not associated with less myocardial oxygen supply; in contrast, heart rate profile showed parallel increases during the morning and afternoon hours, indicating elevated myocardial demand during these periods. Ischemia-related ventricular arrhythmias were concentrated during the morning hours, but their overall prevalence was low--28 (6%) of 437 ischemic episodes. These findings may provide further insight into the pathomechanisms of acute clinical events in patients with coronary artery disease, since the circadian variation of myocardial ischemia is very similar to that observed for the onset of myocardial infarction and sudden cardiac death.

Adult↗
PubMed1997

Fertility levels and trends in the face of the AIDS epidemic in Uganda.

The paper uses data on ever-married women interviewed in 1992 and 1995 surveys in six districts of Uganda. Total fertility rates declined during the inter-survey period from 7.3 to 6.0. Women in households that experienced AIDS-related deaths had lower fertility levels than women in non-AIDS-affected households in both 1992 and 1995. This pattern was true of women at older ages, in polygamous unions, the widowed and separated, and among the highly educated and the uneducated.

Adolescent↗
PubMed1999

[Mechanism of spontaneous occurrence of tachycardia].

Tachycardias arise from an arrhythmogenic substrate and a trigger factor, an extrasystole, the two factors being under the influence of the autonomic nervous system. The study of the mechanisms of spontaneous initiation of arrhythmias must, therefore, take these three factors and their interactions into account. The frequency dependency of an arrhythmia and the sensitivity of the substrate to the adrenergic system varies with time in a given subject and from one patient to another according to the presence and type of cardiac disease. The mode of initiation of most ventricular tachycardias and the therapeutic consequences may be understood: in some forms of cardiac disease, such as arrhythmogenic right ventricular dysplasia, the increase in heart rate which usually precedes sustained ventricular arrhythmias is only perceptible in mild or recent forms, unlike the more chronic dysplasias. This suggests that the arrhythmogenic substrate becomes more sensitive to catecholamines with time, and therefore requires smaller changes in sympathetic tone in order to be expressed (adrenergic paradox). Heart rate changes accompany modifications of sinus variability. Holter monitoring has shown, and this has been confirmed by recordings obtained from patients with implanted automatic defibrillators, that global sinus variability decreases before the initiation of a ventricular arrhythmia. Studies of the dynamics of ventricular repolarisation should also confirm the changes of QT frequency-dependency. The analysis of the initiation of arrhythmias would only have an academic interest if this was limited to a purely descriptive exercise. It is one of the best means of understanding arrhythmias and their therapeutic implications. The development of computerised methods of analysis of Holter monitoring should lead to further progress in this field.

Cardiomegaly↗
PubMed1999

Congenital syphilis--United States, 1998.

Congenital syphilis (CS) occurs when the spirochete Treponema pallidum is transmitted from a pregnant woman with syphilis to her fetus. A multiorgan infection, CS may result in a neurologic or musculoskeletal handicap or death in the fetus when not properly treated. Trends in CS rates in women of childbearing age follow by approximately 1 year the rates of primary and secondary syphilis. The last national syphilis epidemic, which was followed by a CS epidemic, occurred during the late 1980s and early 1990s. The syphilis rate began to decline in 1991; the CS rate began to decline in 1992. To evaluate CS epidemiology since this decline, CDC analyzed 1998 CS notifiable disease data and assessed rate changes during 1992-1998. This report summarizes the results, which indicate that the CS rate declined 78.2% from 1992 to 1998, and that rates remained disproportionately high in the southeastern United States and among minority racial/ethnic populations.

Adolescent↗
PubMed1987

A new technique to determine the correlation between the QT interval and heart-rate for control and SIDS babies.

The ability of the autonomic nervous system to alter the QT interval in response to heart rate changes is essential to cardiovascular control. An accurate way to determine the relation between QT intervals and their corresponding RR intervals is described. A computer algorithm measures the RR intervals using digital filtering and cross-correlating the QRS sections of consecutive waveforms. The QT intervals is calculated by choosing a section of, the ECG that includes the T wave and cross-correlating it with all the consecutive T waves. At least 4000 pairs of QT-RR intervals are computed for each subject and a best fit correlation function determines the relations between the QT and RR intervals. This technique enables to establish a precise correlation between RR and QT in order to distinguish between control and SIDS babies.

Algorithms↗
PubMed1985

Biplot models applied to cancer mortality rates.

"A graphical method developed by Gabriel to display the rows and columns of a matrix is applied to tables of age- and period-specific cancer mortality rates. It is particularly useful when the pattern of age-specific rates changes with time. Trends in age-specific rates and changes in the age distribution are identified as projections. Three examples [from England and Wales] are given."

Age Distribution↗
PubMed2004

[Relationship between heart rate changes during reflex tests and heart rate variability in patients with recent myocardial infarction].

BACKGROUND: Low heart rate variability (HRV) reflecting predominance of sympathetic tone is an independent predictor of sudden cardiac death after myocardial infarction (MI). We have previously shown that decreased heart rate (HR) response during reflex tests (breathing 6 per minute and Valsalva maneuver at the end of the first week after MI is also associated with elevated risk of sudden death during subsequent 2 years. AIM: To elucidate relationship between HR response to breathing 6 per minute and Valsalva maneuver, and HRV as standard non-invasive method of assessment of autonomic regulation of the heart. MATERIAL: Tests with breathing 6 per minute and Valsalva maneuver were performed on 4-11 (median 8) days of MI in 188 patients (68.1% males) aged 34-75 (median 62) years, 93.6% of whom received beta-blockers. Parameters studied were difference between maximal and minimal HR during 1(st) min of controlled breathing (DHR) and Valsalva ratio (VR). Standard time- and frequency-domain HRV measures were calculated from 15-min ECG strips at bed rest just before tests and from 24-hour ECG recordings after tests. RESULTS: In patients with low values of DHR (<3.36) and VR (<1,13) most of HRV parameters were also significantly decreased. Most close association was found between low DHR and low SDNNi and LF power calculated from 24-hour Holter recordings, between low VR and low LF power at bed rest. CONCLUSION: Direct correlation between HR response to reflex tests and parameters of HRV allows to suggest that decreased HR response to controlled breathing and Valsalva maneuver in patients with recent MI also reflects presence of marked sympathetic predominance.

Autonomic Nervous System↗
PubMed2004

Decades of disparity: widening ethnic mortality gaps from 1980 to 1999.

BACKGROUND: Maori and Pacific deaths were severely undercounted in the mid-1980s and first half of 1990s, resulting in numerator-denominator bias when calculating mortality rates by ethnicity. We used the New Zealand Census-Mortality Study to adjust for this bias and calculate corrected ethnic-specific mortality rates from 1980 to 1999. METHODS: Age-specific adjusters were calculated for the period 1980-99. They were applied to mortality data to obtain a corrected number of deaths. Mortality rates (by age and gender) were calculated by dividing the total number of adjusted deaths by the respective census counts. RESULTS: Contrary to unadjusted rates, corrected Maori and Pacific mortality rates were clearly higher than non- Maori non-Pacific rates during the 1980s and early 1990s. From 1980-84 (1361 per 100,000 for males and 965 per 100,000 for females) to 1996-99 (1258 and 894), there was only a modest decrease in Maori 1 to 74 year old mortality rates. Pacific mortality rates changed little from 1980-84 (1264 and 672) to 1996-99 (1144 and 696 per 100,000 for males and females respectively). Non-Maori non-Pacific mortality rates, however, decreased by about 30% from 1980-84 (919 and 553) to 1996-99 (641 and 407 per 100,000 for males and females, respectively). Cancer (lung, prostate, breast, colorectal) mortality rates tended to increase over time among Maori compared to steadily decreasing among non-Maori non-Pacific. Of note, Pacific colorectal cancer mortality rates have increased by about ten-fold during the 1980s and 1990s. All ethnic groups experienced falls in cardiovascular disease mortality rates, but the decreases were much greater among non-Maori non-Pacific. CONCLUSION: The gaps between Maori and non-Maori non-Pacific mortality widened over the 1980s and 1990s mainly due to steadily declining non-Maori non-Pacific mortality rates and stagnant Maori mortality rates. Likewise, the gaps between Pacific and non-Maori non-Pacific mortality also widened during that period.

Adolescent↗
PubMed1987

[Studies on the interrelation of fetal heart rate change, placental findings and fetal outcome].

The relation between antepartum fetal heart rate (FHR) non stress test (NST), maternal serum estriol, intrapartum FHR change, birth weight, placental findings and Apgar score were studied in 168 normal gestations and 36 high-risk pregnancies including 25 EPH-gestosis cases. The frequency of placental infarcts was higher in severe gestosis than in other high-risk pregnancies and normal gestation. Abnormal NST was more frequent in high-risk pregnancy than normal. Light for date (LFD) infants were more numerous in high-risk pregnancy than normal, and also frequent in the cases of placental infarcts. Particularly in high-risk pregnancy patients with abnormal NST and placental infarcts, 3 out of 5 showed LFD infants. Intrapartum fetal distress was more common in the cases of abnormal NST than normal. The five minute Apgar score was lower in the patients with abnormal NST and in the cases of placental infarcts than normal. The placental infarct ratio was higher in high-risk pregnancies with abnormal NST than normal. The maternal serum estriol level was not changed in cases of high-risk pregnancy, abnormal NST or placental infarcts when compared to normal gestation. The cases of succeeding fetal death, however, showed a low serum estriol level. In conclusion, antepartum abnormal NST suggests severe placental dysfunction caused by its infarcts and the prognosis is poor in patients with high-risk pregnancies, particularly EPH-gestosis. Coping with abnormal antepartum NST is regarded as important in fetal management.

Apgar Score↗
PubMed1996

[Increasing use of cesarean section, even in developing countries].

At Kaziba hospital in rural Zaire, the frequency of deliveries by Caesarean section rose from 6.2% in 1971 to 12% in 1992, and the fraction of repeated sections rose from 17% to 49%. During the same period, the overall maternal mortality decreased from 0.3% to 0.12%, and deaths connected with Caesarean section from 3.2% to 0.7%, but still the risk of dying remained 13 times higher for births by Caesarean section compared with vaginal deliveries. The frequency of vacuum deliveries was halved during the period, and mean birth weight decreased by about 100 g. Perinatal mortality remained at about 2%. Among 760 Caesarean sections performed in the years 1991 and 1992, 93% were emergency cases. Spinal anesthesia was used in 97%, and blood transfusion was given to 4% of the women. The main indications were mechanical (30%), previous Caesarean section (20%), foetal asphyxia (19%), and suspected uterine rupture (10%). Uterine rupture was verified in 37 cases (4.9%), of which 27 were Caesarean scar ruptures. 259 of the operations were performed by a nurse or a dentist. Operations carried out by persons other than physicians were complicated by wound infections at a higher rate (20.8%) than those carried out by experienced doctors (11.2%). In areas with a poorly developed health system, a high rate of Caesarean section represents a hazard to maternal health. The need for knowledge about alternative methods like vaginal extraction, symphyseotomy and active management of labour is underlined.

Cesarean Section↗