Miroslav Souček

Variability of Phase Shift Between Blood Pressure and Heart Rate Fluctuations A Marker of Short-Term Circulation Control

Background We postulated that the variability of the phase shift between blood pressure and heart rate fluctuation near the frequency of 0.10 Hz might be useful in assessing autonomic circulatory control. Methods and Results We tested this hypothesis in 4 groups of subjects: 28 young, healthy individuals; 13 elderly healthy individuals; 25 patients with coronary heart disease; and 19 patients with a planned or implanted cardioverterdefibrillator (ICD recipients). Data from 5 minutes of free breathing and at 2 different, controlled breathing frequencies (0.10 and 0.33 Hz) were used. Clear differences (P<0.001) in variability of phase were evident between the ICD recipients and all other groups. Furthermore, at a breathing frequency of 0.10 Hz, differences in baroreflex sensitivity (P<0.01) also became evident, even though these differences were not apparent at the 0.33‐Hz breathing frequency. Conclusions—The frequency of 0.10 Hz represents a useful and potentially important one for controlled breathing, at which differences in blood pressure‐RR interactions become evident. These interactions, whether computed as a variability of phase to define stability of the blood pressure‐heart rate interaction or defined as the baroreflex sensitivity to define the gain in heart rate response to blood pressure changes, are significantly different in patients at risk for sudden arrhythmic death. In young versus older healthy individuals, only baroreflex gain is different, with the variability of phase being similar in both groups. These measurements of short‐term circulatory control might help in risk stratification for sudden cardiac death. (Circulation. 2003;108:292‐297.)

Short-term Effects of Cardiac Resynchronization Therapy on Sleep-Disordered Breathing in Patients With Systolic Heart Failure

OBJECTIVES We evaluated the short-term effect of cardiac resynchronization therapy (CRT) on sleep apnea in patients with systolic heart failure. BACKGROUND Sleep-disordered breathing is common in patients with left ventricular systolic dysfunction. METHODS Twelve patients (mean [+/-SE] age, 59.6+/-7.8 years; mean left ventricular ejection fraction, 28.0+/-2.8%) with an implanted atrial-synchronized biventricular pacemaker for the treatment of left ventricular systolic dysfunction were selected and studied. Each subject underwent polysomnography on 3 consecutive nights with CRT on the first night, CRT off the second night, and CRT on the third night. Echocardiography was performed prior to each polysomnogram. RESULTS The central sleep event index (ie, the number of central sleep apneas [CSAs] and hypopneas per hour of sleep) score was lower with CRT compared to that without CRT (mean central sleep event index score with CRT on, 6.9+/-1.7 events per hour of sleep; mean central sleep event index score with CRT off, 14.3+/-2.9 events per hour of sleep; mean central sleep event index score with CRT on, 8.1+/-1.5 events per hour of sleep; p<0.001). Similarly, the cumulative duration of central sleep events (the number of minutes per hour of sleep during CRT) was one half that observed without CRT (CRT on, 2.8+/-0.7 min per hour of sleep; CRT OFF 6.2+/-1.2 min per hour of sleep; CRT ON 3.1+/-0.7 min per hour of sleep; p<0.001). There was a significant correlation between mitral regurgitant volume and central sleep event index on all three nights (r>or=0.77; p<0.01). CONCLUSIONS CRT reduces CSA severity in the short term. This reduction correlated significantly with the CRT-mediated reduction of mitral regurgitation.

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.

RANTES, MCP-1 chemokines and factors describing rheumatoid arthritis.

The MCP-1/CCL2 as well as RANTES/CCL5 chemokines are potent chemoattractants involved in immunoregulatory and inflammatory processes of rheumatoid arthritis. Recent studies demonstrated elevated levels of MCP-1 and RANTES in plasma, synovial fluid, and the synovial tissue of patients with RA. To examine the relationship among MCP-1 and RANTES single nucleotide polymorphisms and circulating levels and rheumatoid arthritis (RA), a total of 156 RA patients and 125 controls were recruited into the study. An association of -855 C/G MCP-1 polymorphism to IgM RF within the RA patients was observed. The lowest circulating levels of RANTES were observed in the AA variant of RANTES -403 G/A polymorphism. Furthermore, an association of -403 AA variant to circulating levels of IL-15 and IL-10 was found. No associations of factors describing rheumatoid arthritis (RFs, ANA, anti-CCP-positive/negative, DAS 28 score and number of swollen joints) with MCP-1 levels, genotype distribution, allelic frequencies and/or frequencies of haplotypes composed of all three studied polymorphisms in promoter region of MCP-1, and RANTES polymorphism were observed. We conclude that the RANTES promoter polymorphism is associated to circulating levels of RANTES, IL15 and IL10. However, our findings suggest that polymorphisms in the MCP-1 and RANTES gene promoters do not contribute significantly to the interindividual RA susceptibility and/or severity in Caucasians.

Main results of the Ouabain and Adducin for Specific Intervention on Sodium in Hypertension Trial (OASIS-HT): a randomized placebo-controlled phase-2 dose-finding study of rostafuroxin

BackgroundThe Ouabain and Adducin for Specific Intervention on Sodium in Hypertension (OASIS-HT) Trial was a phase-2 dose-finding study of rostafuroxin, a digitoxygenin derivative, which selectively antagonizes the effects of endogenous ouabain (EO) on Na+,K+-ATPase and mutated adducin. Rostafuroxin lowered blood pressure (BP) in some animal models and in humans.MethodsOASIS-HT consisted of 5 concurrently running double-blind cross-over studies. After 4 weeks without treatment, 435 patients with uncomplicated systolic hypertension (140-169 mm Hg) were randomized to rostafuroxin (0.05, 0.15, 0.5, 1.5 or 5.0 mg/d) or matching placebo, each treatment period lasting 5 weeks. The primary endpoint was the reduction in systolic office BP. Among the secondary endpoints were diastolic office BP, 24-h ambulatory BP, plasma EO concentration and renin activity, 24-h urinary sodium and aldosterone excretion, and safety. ANOVA considered treatment sequence (fixed effect), subjects nested within sequence (random), period (fixed), and treatment (fixed).ResultsAmong 410 analyzable patients (40.5% women; mean age, 48.4 years), the differences in the primary endpoint (rostafuroxin minus placebo) ranged from -0.18 mm Hg (P = 0.90) on 0.15 mg/d rostafuroxin to 2.72 mm Hg (P = 0.04) on 0.05 mg/d. In the 5 dosage arms combined, the treatment effects averaged 1.30 mm Hg (P = 0.03) for systolic office BP; 0.70 mm Hg (P = 0.08) for diastolic office BP; 0.36 mm Hg (P = 0.49) for 24-h systolic BP; and 0.05 mm Hg (P = 0.88) for 24-h diastolic BP. In the 2 treatment groups combined, systolic (-1.36 mm Hg) and diastolic (-0.97 mm Hg) office BPs decreased from week 5 to 10 (P for period effect ≤0.028), but carry-over effects were not significant (P ≥ 0.11). All other endpoints were not different on rostafuroxin and placebo. Minor side-effects occurred with similarly low frequency on rostafuroxin and placebo.ConclusionsIn 5 concurrently running double-blind cross-over studies rostafuroxin did not reduce BP at any dose.Trial RegistrationClinicalTrials (NCT): NCT00415038

Caffeine and cardiovascular diseases: critical review of current research

Abstract Caffeine is a most widely consumed physiological stimulant worldwide, which is consumed via natural sources, such as coffee and tea, and now marketed sources such as energy drinks and other dietary supplements. This wide use has led to concerns regarding the safety of caffeine and its proposed beneficial role in alertness, performance and energy expenditure and side effects in the cardiovascular system. The question remains “Which dose is safe?”, as the population does not appear to adhere to the strict guidelines listed on caffeine consumption. Studies in humans and animal models yield controversial results, which can be explained by population, type and dose of caffeine and low statistical power. This review will focus on comprehensive and critical review of the current literature and provide an avenue for further study.

Increased Cardio-ankle Vascular Index in Hyperlipidemic Patients without Diabetes or Hypertension

AIM The cardio-ankle vascular index (CAVI) is a sensitive non-invasive marker of arterial stiffness and atherosclerosis. The aim of this work was to compare the CAVI values in patients with dyslipidemia (without diabetes mellitus and hypertension) and healthy controls. METHODS A Total 248 subjects with dyslipidemia (104 men, 144 women), 55.0 (95% CI 30-70) years of age with combined hyperlipidemia or primary hypercholesterolemia and 537 healthy controls (244 men, 293 women) 40.0 (95% CI 26-62) years of age were included in this study. Fasting blood samples were collected to measure the serum total cholesterol, triglyceride, HDL-cholesterol and apolipoprotein A1 and B levels. The LDL cholesterol level was also calculated, and the CAVI was measured using the VaSera(®) 1500 system. RESULTS The CAVI values were significantly higher in the dyslipidemic patients (8.08, 95% CI 6.00-10.05) than in the controls (7.11, 95% CI 5.77-9.05; p < 0.01). In addition, the CAVI values were elevated in both subgroups of patients with hypercholesterolemia (7.95, 95% CI 5.85-6.90; p < 0.01) and combined hyperlipidemia (8.30, 95% CI 6.60-10.15; p < 0.01) in comparison with those observed in the controls. After adopting the propensity score method in order to balance the confounding factors (age, gender, body mass index) and adjust the analysis for diastolic blood pressure, the CAVI values in the dyslipidemic patients remained significantly high (7.78, 95% CI 5.80-9.69) compared to that observed in the controls (7.31, 95% CI 5.44-9.35; p < 0.001). However, the CAVI values did not differ significantly between the controls and both subgroups of dyslipidemic patients(primary hypercholesterolemia, combined hyperlipidemia). CONCLUSIONS The present findings demonstrated that dyslipidemia increases the CAVI values in comparison to that seen in healthy subjects.

An association of BMI with A (-6) G, M235T and T174M polymorphisms in angiotensinogen gene in essential hypertension

The aim of the study was to assess the existence of possible associations among frequent polymorphisms in angiotensinogen genes and some of the risk factors for essential hypertension, especially body mass index (BMI) and smoking. A total of 192 control subjects (aged 45.87 ± 3.0 years) and 206 patients with the essential hypertension (aged 48.71 ± 8.42 years) were compared at three angiotensinogen gene polymorphisms by considering BMI and smoking status. No significant differences in genotype and/or allelic distribution for either A (-6) G ATG, M235T or T174M polymorphisms between the hypertensive and control groups were proved. Significantly more hypertensives than control persons with BMI above 25 kg/m2 were observed (Pcorr = 0.009), independently on sex distribution. A percentage of 44.6% of smokers in the control group vs 46.0% of smokers in the hypertensive groups were found. No significant difference in concurrence of BMI above 25 kg/m2 and positive smoking status between control and hypertensive subjects was found. Statistically significant differences were found between control and hypertensive subjects when compared distributions of subjects with certain genotypes of the three examined polymorphisms considering BMI (Pcorr = 0.0002 for AA+AG of A (-6) G ATG, Pcorr = 0.01 for CC+CT of T(174)M ATG and Pcorr = 0.01 for MT+TT of M235T ATG). No functional relationship among obesity and the examined polymorphisms in vivo are known. We conclude that a different distribution of BMI could influence the results of analyses of angiotensinogen gene polymorphisms in essential hypertension-control studies.

Dynamic coupling between heart rate and ventricular repolarisation

Abstract A novel model for the coupling between ventricular repolarisation and heart rate (QT/RR) is presented. It is based upon a transfer function (TRF) formalism that describes the static and dynamic properties of this coupling, i.e., the behaviour after a sudden change in heart rate. Different TRF models were analysed by comparing their capability to describe experimental data collected from 19 healthy volunteers using several RR stimulation protocols: (i) rest with deep breathing at 0.1 Hz; (ii) tilt with controlled breathing at 0.1 and 0.33 Hz; and (iii) cycling. A search for the best TRF led to unambiguous identification of a three-parameter model as the most suitable descriptor of QT/RR coupling. Compared with established static models (linear or power-law), our model predictions are substantially closer to the experimental results, with errors ∼50% smaller. The shape of the frequency and step responses of the TRF presented is essentially the same for all subjects and protocols. Moreover, each TRF may be uniquely identified by three parameters obtained from the step response, which are believed to be of physiological relevance: (i) gain for slow RR variability; (ii) gain for fast RR variability; and (iii) time during which QT attains 90% of its steady-state value. The TRF successfully describes the behaviour of the RR control following an abrupt change in RR interval, and its parameters may offer a tool for detecting pharmacologically induced changes, particularly those leading to increased arrhythmogenic risk.

Association of the 5A/6A promoter polymorphism of the MMP-3 gene with the radiographic progression of rheumatoid arthritis

Abstract:  Matrix metalloproteinases (MMPs) as a family of zinc‐dependent endopeptidases have been involved in remodeling the extracellular matrix (ECM) in rheumatoid arthritis (RA). In RA patients synovial fluid and serum include enhanced levels of MMP‐3. The 5A/6A polymorphism in the MMP‐3 gene promoter can contribute to the severity of RA on account of a higher promoter activity of the 5A allele in vitro. The aim of the study was to associate the 5A/6A polymorphism of the MMP‐3 gene with radiographic progression of RA. A total of 128 RA patients according to the ACR criteria were available for the study. Radiographs of both hands, obtained from all RA patients, were scored using the modified Sharp/van der Heijde method and the Steinbrocker method. The total Sharp score (TSS) and the annual radiographic progression rate (TSS/year) were calculated. Significant association with the 5A/6A polymorphism was found between patients with TSS/year ≤ 1.00 and those with TSS/year > 1.00 in allelic frequencies (Pa= 0.046) and also in genotype distribution (Pg= 0.04). Compared to other genotypes the prevalence of 5A/5A genotype was lower within patients with TSS/year ≤ 1.00 (odds ratio [OR]= 0.2; 95% confidence interval [CI] 0.04–0.85; P= 0.01). Also, in comparison to genotypes 5A/6A and 5A/5A, the prevalence of 6A/6A genotype was higher within patients with nonerosive RA (OR = 2.65; 95% CI 1.03–6.83, P= 0.02). Results obtained in this study provide the evidence of an association of the 5A/6A promoter polymorphism of the MMP‐3 gene to the radiographic progression of RA.