Possibilities of Interpreting the Night-to-Day Ratio Specified by 24-Hour Blood Pressure Monitoring.

Aim: Specify the risk rate of incorrect patient classification based on the night-to-day ratio specification from singular 24-h ABPM in comparison to the results of 7-day ABPM monitoring. Materials and Methods: 1197 24 h cycles were enrolled in 171 subjects in the study and divided into 4 groups: group 1 (40 healthy men and women without exercise), group 2 (40 healthy exercise-training men and women), group 3 (40 patients with ischemic coronary artery disease without exercise), and group 4 (51 patients with ischemic coronary artery disease following cardiovascular rehabilitation). The subject of the evaluation was the percentage rate of incorrect subject classification (dipper, nondipper, extreme dipper, and riser) based on the mean blood pressure values for 7 days and from seven independent 24-hour cycles (the mean value mode). Results: In the case of the individuals included in the monitored groups, the mean night-to-day ratio-based (mode for the 7 days versus the individual days of 24-hour monitoring) classification accordance ranged between 59% and 62%. Only in singular cases did the accordance reach 0% or 100%. The accordance size was not dependent on the health or cardiovascular disease (p < 0.594; 56% vs. 54%) or physical activity (p < 0.833; 55% vs. 54%) of the monitored individuals. Conclusion: The specification of the night-to-day ratio of each individual for each day of the 7-day ABPM monitoring would be the most convenient option. In many patients, diagnosing could thus be based on the most frequently occurring values (mode specification).

Intra-dialytic electrostimulation of leg extensors may improve exercise tolerance and quality of life in hemodialyzed patients.

Hemodialyzed (HD) patients with end-stage renal disease (ESRD) exhibit lower fitness as a consequence of chronic uremic changes that trigger various structural, metabolic, and functional abnormalities in skeletal muscles. The aim of this randomized study was to compare the effect of rehabilitation (RHB) training on a bicycle ergometer and electromyostimulation (EMS) of leg extensors in HD patients with ESRD. Thirty-two HD patients (18 men/14 women; mean age 61.1 ± 8.8 years) were randomized into three groups: (i) exercise training (ET; n = 11) on bicycle ergometer 2 × 20 min; (ii) EMS (n = 11) where stimulation (10 Hz) of leg extensors was applied for 60 min; and (iii) controls (CON; n = 10) without exercise. Exercising was performed between the 2nd and the 3rd hour of HD, three times a week, 20 weeks in total. Ergometric test was performed in order to evaluate peak workload (W(peak)), 6-min corridor walking test (CWT) to evaluate the distance walked, and dynamometry of leg extensors to assess muscle power (F(max)). Urea clearance was monitored and expressed as standard parameters: spKt/V, spKt/V equilibrated (spKt/V-e), and the urea removal ratio (URR). Quality of life (QoL) was assessed by the questionnaire SF-36. A significant increase of F(max) (P = 0.040 in group ET; P = 0.032 in group EMS), of 6-min CWT (P < 0.001 in ET group; P = 0.042 in EMS group), and of W(peak) (P = 0.041 in ET group) was observed. In both exercising groups, significant increase of spKt/V, spKt/V-e, and URR was found as compared with initial values (P < 0.05). In both exercising groups, highly significant changes in summarized mental functions were found (P = 0.001); in summarized physical components, significant improvement was observed in the ET group (P = 0.006). Intradialytic RHB showed comparable positive effects on functional parameters, urea clearance, and QoL. Intradialytic EMS might represent wide therapeutic possibility in the near future.

Effects of neuromuscular electrical stimulation and aerobic exercise training on arterial stiffness and autonomic functions in patients with chronic heart failure.

Neuromuscular electrical stimulation (NMES) of leg muscles has been introduced in clinical practice as a rehabilitation (RHB) method in patients with chronic heart failure (CHF); however, the role of NMES on the reduction of arterial stiffness and autonomic disbalance in these patients has not yet been studied. Sixty-one patients with stable CHF (mean age 58.9 [2.1] years; mean ejection fraction 31 [4.2]%, New York Heart Association II-III) were randomly assigned into two groups. Patients in (i) exercise training group (ET; n = 30) underwent 12 weeks of bicycle ET (3 × 40 min/week); (ii) group NMES (n = 31) performed 12 weeks of NMES of quadriceps and calf muscles (frequency 10 Hz, mode "20 s on-20 s off," intensity 60 mA), 2 × 60 min/day. Noninvasive assessment of arterial stiffness was done using the cardio-ankle vascular index (CAVI). CAVI and heart rate variability (HRV) and ·VO(2peak) were evaluated before and after RHB program. Both types of RHB reduced significantly CAVI (ET from 9.6 [0.2] to 8.9 [0.2], P < 0.012; NMES from 9.3 [0.2] to 8.7 [0.2], P < 0.013), increased high frequency (HF) component of HRV (+65.6%; P = 0.001) and decreased ratio of low frequency (LF) component with HF component (LF/HF ratio) in group ET (-39.8%; P < 0.001). Changes of HRV parameters in group NMES were not significant; however, a marked tendency to autonomic stabilization was present. Both types of RHB led also to significant increase of ·VO(2peak) (ET from 18.7 [0.7] to 20.8 [0.7] mL/kg/min, P < 0.004; NMES from 17.3 [0.7] to 19.0 [0.7] mL/kg/min, P < 0.001). ET or NMES has been shown to improve significantly arterial stiffness and to stabilize autonomic balance.

Benefit of combined cardiac rehabilitation on exercise capacity and cardiovascular parameters in patients with type 2 diabetes.

Favorable effects of exercise training on cardiovascular prognosis have been reported repeatedly in patients with diabetes mellitus type 2 (DM2). However, little is known about the cardiovascular rehabilitation effects in diabetic patients with coronary artery disease (CAD). This study has evaluated the benefits of combined aerobic-resistance training in two groups of patients--diabetics and non-diabetics--after percutaneous coronary intervention (PCI). Changes in exercise capacity parameters, resting cardiovascular and anthropometrical parameters were evaluated in 77 patients who completed 12-weeks of combined aerobic-resistance training: 32 patients with DM2 (DM) and 45 patients without DM2 (NDM). Significant improvements in exercise capacity (total peak workload [W(peak)], peak workload per kg of body weight [W(peak)/kg], total peak oxygen uptake [VO(2peak)], peak oxygen uptake per kg of body weight [VO(2peak)/kg]) were found in both DM and NDM (p < 0.01 and p < 0.001, respectively). The decrease in resting heart rate (HR(rest)), resting systolic (SBP(rest)) resting diastolic (DBP(rest)) blood pressures, body weight (BW) and BMI in the DM group was not statistically significant. However, there was a statistically significant decrease in SBP(rest), BW and BMI in the NDM group. In conclusion, this study demonstrated similar beneficial effects of combined cardiovascular training on exercise capacity in patients with or without type 2 diabetes mellitus. Our results suggest that the combined cardiac training is well tolerated and useful in secondary prevention in patients with DM2 and CAD.

Hypertension types defined by clinic and ambulatory blood pressure in 14 143 patients referred to hypertension clinics worldwide. Data from the ARTEMIS study.

OBJECTIVE: The Ambulatory blood pressure Registry TEleMonitoring of hypertension and cardiovascular rISk project was designed to set up an international registry including clinic blood pressure (CBP) and ambulatory blood pressure (ABP) measurements in patients attending hypertension clinics in all five continents, aiming to assess different daily life hypertension types. METHODS: Cross-sectional ABP, CBP and demographic data, medical history and cardiovascular risk profile were provided from existing databases by hypertension clinics. Hypertension types were evaluated considering CBP (≥140/90 mmHg) and 24-h ABP (≥130/80 mmHg). RESULTS: Overall, 14 143 patients from 27 countries across all five continents were analyzed (Europe 73%, Africa 3%, America 9%, Asia 14% and Australia 2%). Mean age was 57 ±â€Š14 years, men 51%, treated for hypertension 46%, cardiovascular disease 14%, people with diabetes 14%, dyslipidemia 33% and smokers 19%. The prevalence of hypertension was higher by CBP than by ABP monitoring (72 vs. 60%, P < 0.0001). Sustained hypertension (elevated CBP and ABP) was detected in 49% of patients. White-coat hypertension (WCH, elevated CBP with normal ABP) was more common than masked hypertension (elevated ABP with normal CBP) (23 vs. 10%; P < 0.0001). Sustained hypertension was more common in Europe and America and in elderly, men, obese patients with cardiovascular comorbidities. WCH was less common in Australia, America and Africa, and more common in elderly, obese women. Masked hypertension was more common in Asia and in men with diabetes. Smoking was a determinant for sustained hypertension and masked hypertension. CONCLUSION: Our analysis showed an unbalanced distribution of WCH and masked hypertension patterns among different continents, suggesting an interplay of genetic and environmental factors, and likely also different healthcare administrative and practice patterns.

Chronoastrobiology: proposal, nine conferences, heliogeomagnetics, transyears, near-weeks, near-decades, phylogenetic and ontogenetic memories.

"Chronoastrobiology: are we at the threshold of a new science? Is there a critical mass for scientific research?" A simple photograph of the planet earth from outer space was one of the greatest contributions of space exploration. It drove home in a glance that human survival depends upon the wobbly dynamics in a thin and fragile skin of water and gas that covers a small globe in a mostly cold and vast universe. This image raised the stakes in understanding our place in that universe, in finding out where we came from and in choosing a path for survival. Since that landmark photograph was taken, new astronomical and biomedical information and growing computer power have been revealing that organic life, including human life, is and has been connected to invisible (non-photic) forces, in that vast universe in some surprising ways. Every cell in our body is bathed in an external and internal environment of fluctuating magnetism. It is becoming clear that the fluctuations are primarily caused by an intimate and systematic interplay between forces within the bowels of the earth--which the great physician and father of magnetism William Gilbert called a 'small magnet'--and the thermonuclear turbulence within the sun, an enormously larger magnet than the earth, acting upon organisms, which are minuscule magnets. It follows and is also increasingly apparent that these external fluctuations in magnetic fields can affect virtually every circuit in the biological machinery to a lesser or greater degree, depending both on the particular biological system and on the particular properties of the magnetic fluctuations. The development of high technology instruments and computer power, already used to visualize the human heart and brain, is furthermore making it obvious that there is a statistically predictable time structure to the fluctuations in the sun's thermonuclear turbulence and thus to its magnetic interactions with the earth's own magnetic field and hence a time structure to the magnetic fields in organisms. Likewise in humans, and in at least those other species that have been studied, computer power has enabled us to discover statistically defined endogenous physiological rhythms and further direct effects that are associated with these invisible geo- and heliomagnetic cycles. Thus, what once might have been dismissed as noise in both magnetic and physiological data does in fact have structure. And we may be at the threshold of understanding the biological and medical meaning and consequences of these patterns and biological-astronomical linkages as well. Structures in time are called chronomes; their mapping in us and around us is called chronomics. The scientific study of chronomes is chronobiology. And the scientific study of all aspects of biology related to the cosmos has been called astrobiology. Hence we may dub the new study of time structures in biology with regard to influences from cosmo- helio- and geomagnetic rhythms chronoastrobiology. It has, of course, been understood for centuries that the movements of the earth in relation to the sun produce seasonal and daily cycles in light energy and that these have had profound effects on the evolution of life. It is now emerging that rhythmic events generated from within the sun itself, as a large turbulent magnet in its own right, can have direct effects upon life on earth. Moreover, comparative studies of diverse species indicate that there have also been ancient evolutionary effects shaping the endogenous chronomic physiological characteristics of life. Thus the rhythms of the sun can affect us not only directly, but also indirectly through the chronomic patterns that solar magnetic rhythms have created within our physiology in the remote past. For example, we can document the direct exogenous effects of given specific solar wind events upon human blood pressure and heart rate. We also have evidence of endogenous internal rhythms in blood pressure and heart rate that are close to but not identical to the period length of rhythms in the solar wind. These were installed genetically by natural selection at some time in the distant geological past. This interpretive model of the data makes the prediction that the internal and external influences on heart rate and blood pressure can reinforce or cancel each other out at different times. A study of extensive clinical and physiological data shows that the interpretive model is robust and that internal and external effects are indeed augmentative at a statistically significant level. Chronoastrobiological studies are contributing to basic science--that is, our understanding is being expanded as we recognize heretofore unelaborated linkages of life to the complex dynamics of the sun, and even to heretofore unelaborated evolutionary phenomena. Once, one might have thought of solar storms as mere transient 'perturbations' to biology, with no lasting importance. Now we are on the brink of understanding that solar turbulences have played a role in shaping endogenous physiological chronomes. There is even documentation for correlations between solar magnetic cycles and psychological swings, eras of belligerence and of certain expressions of sacred or religious feelings. Chronoastrobiology can surely contribute to practical applications as well as to basic science. It can help develop refinements in our ability to live safely in outer space, where for example at the distance of the moon the magnetic influences of the sun will have an effect upon humans unshielded by the earth's native magnetic field. We should be better able to understand these influences as physiological and mechanical challenges, and to improve our estimations of the effects of exposure. Chronoastrobiology moreover holds great promise in broadening our perspectives and powers in medicine and public health right here upon the surface of the earth. Even the potential relevance of chronoastrobiology for practical environmental and agricultural challenges cannot be ruled out at this early stage in our understanding of the apparently ubiquitous effects of magnetism and hence perhaps of solar magnetism on life. The evidence already mentioned that fluctuations in solar magnetism can influence gross clinical phenomena such as rates of strokes and heart attacks, and related cardiovascular variables such as blood pressure and heart rate, should illustrate the point that the door is open to broad studies of clinical implications. The medical value of better understanding magnetic fluctuations as sources of variability in human physiology falls into several categories: 1) The design of improved analytical and experimental controls in medical research. Epidemiological analyses require that the multiple sources causing variability in physiological functions and clinical phenomena be identified and understood as thoroughly as possible, in order to estimate systematic alterations of any one variable. 2) Preventive medicine and the individual patients'care. There are no flat 'baselines', only reference chronomes. Magnetic fluctuations can be shown statistically to exacerbate health problems in some cases. The next step should be to determine whether vulnerable individuals can be identified by individual monitoring. Such vulnerable patients may then discover that they have the option to avoid circumstances associated with anxiety during solar storms, and/or pay special attention to their medication or other treatments. Prehabilitation by self-help can hopefully complement and eventually replace much costly rehabilitation. 3) Basic understanding of human physiological mechanisms. The chronomic organization of physiology implies a much more subtle dynamic integration of functions than is generally appreciated. All three categories of medical value in turn pertain to the challenges for space science of exploring and colonizing the solar system. The earth's native magnetic field acts like an enormous umbrella that offers considerable protection on the surface from harsh solar winds of charged particles and magnetic fluxes. The umbrella becomes weaker with distance from the earth and will offer little protection for humans, other animals, and plants in colonies on the surface of the moon or beyond. Thus it is important before more distant colonization is planned or implemented to better understand those magnetism-related biological- solar interactions that now can be studied conveniently on earth. (ABSTRACT TRUNCATED)

Cross-spectrally coherent ~10.5- and 21-year biological and physical cycles, magnetic storms and myocardial infarctions*

Magnetic storms trigger myocardial infarctions with mechanisms relating to heart rate variability. Solar cycle-to-solar cycle differences and solar cycle stage dependence shown herein may resolve prior controversy and serve to advocate coordinated worldwide systematically aligned biological and physical monitoring. * This paper was originally invited by the historian-geophysicist Wilfried SCHRöDER of Bremen, Germany, for his biographical "Encounters," and is to serve as an update on the project on the BIOsphere and the Cosmos (BIOCOS) and its offspring ICEHRV (Dr. Kuniaki Otsuka's International Chronome Ecologic Study of Heart Rate Variability). It is intended for distribution at a NATO conference on space weather hazards, organized by Dr. Ioannis Daglis, June 18-29, 2000.

Engineering and governmental challenge: 7-day/24-hour chronobiologic blood pressure and heart rate screening: Part I.

This review provides evidence that the bioengineering community needs to develop cost-effective, fully unobtrusive, truly ambulatory instrumentation for the surveillance of blood pressure and heart rate. With available instrumentation, we document a disease risk syndrome, circadian blood pressure overswinging (CHAT, short for circadian hyper-amplitude-tension). Circadian hyper-amplitude-tension is defined as a week-long overall increase in the circadian amplitude or otherwise-measured circadian variability of blood pressure above a mapped threshold, corresponding to the upper 95% prediction limit of clinically healthy peers of the corresponding gender and age. A consistently reduced heart rate variability, gauged by a circadian standard deviation below the lower 5% prediction limit of peers of the corresponding gender and age, is an index of a separate yet additive major risk, a deficient heart rate variability (DHRV). The circadian amplitude, a measure of the extent of reproducible variability within a day, is obtained by linear curve-fitting, which yields added parameters: a midline-estimating statistic of rhythm, the MESOR (a time structure or chronome-adjusted mean), the circadian acrophase, a measure of timing of overall high values recurring in each cycle, and the amplitudes and acrophases of the 12-hour (and higher order) harmonic(s) of the circadian variation that, with the characteristics of the fundamental 24-hour component, describe the circadian waveform. The MESOR is a more precise and more accurate estimate of location than the arithmetic mean. The major risks associated with CHAT and/or DHRV have been documented by measurements of blood pressure and heart rate at 1-hour or shorter intervals for 48 hours on populations of several hundred people, but these risks are to be assessed in a 7-day/24-hour record in individuals before a physical examination, for the following reasons. (1) The average derived from an around-the-clock series of blood pressure measurements, computed as its MESOR, the proven etiopathogenetic factor of catastrophic vascular disease, can be above chronobiologic as well as World Health Organization limits for 5 days or longer and can be satisfactory for months thereafter, as validated by continued automatic monitoring. The MESOR can be interpreted in light of clock-hour-, gender-, and age-specified reference limits and thus can be more reliably estimated with a systematic account of major sources of variability than by casual time-unspecified spot checks (that conventionally are interpreted by a fixed and, thus, rhythm, gender-, and age-ignoring limit). With spot checks, in a diagnostically critical range of "borderline" blood pressures, an inference can depend on the clock-hour of the measurement, usually providing a diagnosis of normotension in the morning and of hypertension in the afternoon (for the same diurnally active, nocturnally resting patient!). Long-term treatment must not be based upon the possibility of an afternoon vs a morning appointment. Moreover, the conventional approach will necessarily miss cases of CHAT that are not accompanied by MESOR hypertension. (2) Circadian hyper-amplitude-tension indicates a greater risk for stroke than does an increase in the around-the-clock average blood pressure (above 130/80 mm Hg) or old age, whereas (3) CHAT can be asymptomatic, as can MESOR hyptertension. (4) Deficient heart rate variability, the fall below a threshold of the circadian standard deviation of heart rate, an entity in its own right, is also a chronome alteration of heart rate variability (CAHRV). Deficient heart rate variability can be present together with CHAT, doubling the relative risk of morbid events. In each case--either combined with CHAT or as an isolated CAHRV--a DHRV constitutes an independent diagnostic assessment provided as a dividend by current blood pressure monitors that should be kept in future instrumentation designs. CHAT and DHRV can be screened by systematic focus on variability, preferably by the use of automatic instrumentation and analyses, which are both available (affordably) for research in actual practice, in conjunction with the Halberg Chronobiology Center at the University of Minnesota.

Exercise training combined with electromyostimulation in the rehabilitation of patients with chronic heart failure: A randomized trial.

AIM: Both aerobic training (AT) and electromyostimulation (EMS) of leg muscles improve exercise tolerance in patients suffering from chronic heart failure (CHF). It was speculated that combination of both methods might have an additive effect. This study was performed to evaluate the effects of a combination of AT and EMS in rehabilitation (RHB) of CHF patients. PATIENTS AND METHODS: Patients (n=71; age 59 ± 10.2 yrs, NYHA II/III, EF 32 ± 7.1%) were randomized into 3 groups: a) group AT, b) group EMS, and c) group AT+EMS. AT protocol included standard activity on bicycle 3x a week at the level of individual anaerobic threshold. EMS (10 Hz, mode 20s "on"/20s "off") was applied to leg extensors for 2 h/day. Total time of given type of RHB was 12 weeks. RESULTS: Data analysis revealed statistically significant improvements of patients in all experimental groups (averaged difference after 12 weeks of exercise as related to initial value: ∆VO2peak: +12.9%, ∆VO2AT: +9.3%, ∆Wpeak: +22.7%). No statistically significant difference among experimental groups was found. Quality of life (Minnesota Living with Heart Failure - MLHF) global score was significantly improved in all 3 groups: AT (∆MLHF: -27.9%; P=0.001), AT+EMS (∆MLHF: -29.1%; P=0.002), and EMS (∆MLHF: -16.6%; P=0.008). MLHF score in EMS group showed the smallest time-related improvement compared to AT and AT+EMS groups, and this difference in improvement between the groups was statistically significant (P=0.021). CONCLUSION: No significant difference was found between the two types of exercise training.and nor did, their combination have any significant additional improvement.

Chronobiologically Interpreted Ambulatory Blood Pressure Monitoring in Health and Disease.

To detect vascular variability anomalies (VVAs), a blood pressure and heart rate profile around the clock for at least 7 days is a start. As a minimum, measurement every 60 or preferably 30 minutes for a week is needed, to be continued if abnormality is found, to assess the about 24-hour (circadian) variability that exists in all individuals. As a first dividend, one then also obtains a glimpse of 2 of the very many longer-than-circadian periodicities, the biological half-week and week. Certainly if we can have sensors and computer chips in our cars that continuously monitor the pressure over a tire's life, we should be able to do the same job for ourselves for diagnostic and therapeutic decisions. Healthcare today emphasizes wellness with recommendations for exercise and a proper diet, yet these evaluations may not be adequate. BP may be measured at a visit to the doctor or before an exercise session, along with measuring body weight and performing a physical exam. The seeds of disease are planted long before they are visible, and what appears to be normal from a conventional point of view may in fact actually be abnormal. Hidden alterations of physiological function, masked by the body's remarkable adaptive capabilities, may become visible through a new diagnostic and therapeutic realm-chronobiology-that reveals hitherto unseen abnormalities. The tools of chronobiology may yield additional dividends, such as the detection of physiological "loads" related to stress and stress relief and the undesirable effcts of space weather upon personal events such as sudden cardiac death, societal events like terrorism and war, and natural disasters. Chronobiologi cally interpreted automatic ambulatory BP and heart rate (HR) monitoring (C-ABPM) may detect the antecedents of these types of events. C-ABPM is of interest in preventive cardiology, since it reveals new diagnoses as vascular variability anomalies (VVAs) and renders previous conventional diagnoses more reliable, such as that of an elevated BP. These VVAs include MESOR (midline-estimating statistic of rhythm)-hypertension, an elevation of the MESOR, which is diagnosed, like all other VVAs, only after I or preferably several replications of 7-day around-the-clock BP monitoring with available, affordable, and unobtrusive instrumentation. The recommendation for continuous C-ABPM recognizes several principles that constitute inseparably intertwined contributors to severe cardio-, cerebro- and renovascular diease. C-ABPM gauges wear and tear of genetics, physical loads, and in particular mental stress placed upon individuals from "womb to tomb" by daily life, including weather in extraterrestrial space as well as that on earth, as a continuous surveillance paradigm preventing us from flying blind to a change from less than 5% to near 100% in the risk of a stroke within 6 years.

Home C-ABPM for Preventive and Curative Health Care and Transdisciplinary Science.

The clinical everyday management of blood pressure (BP) and heart rate (HR) can be greatly improved by the mapping of time structures in home ambulatory BP and HR assessment. Thereby, we change focus from the BP and the HR to the dynamics of these variables. This change is achieved by computer-implemented chronomics, the mapping of chronomes, consisting of cyclicities (our concern herein) along with chaos and trends, in the service of cardiologists, general health care providers, the educated public, and transdisciplinary science. We here further illustrate the yield of chronomics in research on long BP and HR series covering years, some several decades long, and on archives of human sudden cardiac death revealing magnetoperiodisms, e.g., "years" longer than a calendar year, i.e., transyears. In this case of cardiac arrest, what we do not see, the 16- to 20-month transyear is prominent, in the absence of any signature of the calendar year, and so can be a cis-half-year of about 5 months.

Low-frequency electrical stimulation increases muscle strength and improves blood supply in patients with chronic heart failure.

BACKGROUND: This study was designed to evaluate the effects of low-frequency electrical stimulation (LFES) on muscle strength and blood flow in patients with advanced chronic heart failure (CHF). METHODS AND RESULTS: Patients with CHF (n=15; age 56.5 +/- 5.2 years; New York Heart Association III - IV; ejection fraction 18.7 +/- 3.3%) were examined before and after 6 weeks of LFES (10 Hz) of the quadriceps and calf muscles of both legs (1 h/day, 7 days/week). Dynamometry was performed weekly to determine maximal muscle strength (F(max); N) and isokinetic peak torque (PT(max); Nm); blood flow velocity (BFV) was measured at baseline and after 6 weeks of LFES using pulsed-wave Doppler velocimetry of the right femoral artery. Six weeks of LFES significantly increased F(max) (from 224.5 +/- 96.8 N to 340.0 +/- 99.4 N; p<0.001), and also PT(max) (from 94.5 +/- 41.5 Nm to 135.3 +/- 28.8 Nm; p<0.01). BFV in the femoral artery increased after 6 weeks from 35.7 +/- 15.4 cm/s to 48.2 +/- 18.1 cm/s (p<0.05); BFV values at rest before and after 6 weeks of LFES did not differ significantly. CONCLUSIONS: LFES may improve muscle strength and blood supply, and could be recommended for the treatment of patients with severe CHF.

Electrical stimulation of skeletal muscles. An alternative to aerobic exercise training in patients with chronic heart failure?

The aim of this study was to investigate whether electrical stimulation of skeletal muscles could represent a rehabilitation alternative for patients with chronic heart failure (CHF). Thirty patients with CHF and NYHA class II-III were randomly assigned to a rehabilitation program using either electrical stimulation of skeletal muscles or bicycle training. Patients in the first group (n = 15) had 8 weeks of home-based low-frequency electrical stimulation (LFES) applied simultaneously to the quadriceps and calf muscles of both legs (1 h/day for 7 days/week); patients in the second group (n = 15) underwent 8 weeks of 40 minute aerobic exercise (3 times a week). After the 8-week period significant increases in several functional parameters were observed in both groups: maximal VO2 uptake (LFES group: from 17.5 +/- 4.4 mL/kg/min to 18.3 +/- 4.2 mL/kg/min, P < 0.05; bicycle group: from 18.1 +/- 3.9 mL/kg/min to 19.3 +/- 4.1 mL/kg/min, P < 0.01), maximal workload (LFES group: from 84.3 +/- 15.2 W to 95.9 +/- 9.8 W, P < 0.05; bicycle group: from 91.2 +/- 13.4 W to 112.9 +/- 10.8 W, P < 0.01), distance walked in 6 minutes (LFES group: from 398 +/- 105 m to 435 +/- 112 m, P < 0.05; bicycle group: from 425 +/- 118 m to 483 +/- 120 m, P < 0.03), and exercise duration (LFES group: from 488 +/- 45 seconds to 568 +/- 120 seconds, P < 0.05; bicycle group: from 510 +/- 90 seconds to 611 +/- 112 seconds, P < 0.03). These results demonstrate that an improvement of exercise capacities can be achieved either by classical exercise training or by home-based electrical stimulation. LFES should be considered as a valuable alternative to classical exercise training in patients with CHF.