Heart rate variability analysed by Poincaré plot in patients with metabolic syndrome.

INTRODUCTION: The SD1 and SD2 indexes (standard deviations in two orthogonal directions of the Poincaré plot) carry similar information to the spectral density power of the high and low frequency bands but have the advantage of easier calculation and lesser stationarity dependence. METHODS: ECG signals from metabolic syndrome (MetS) and control group patients during tilt table test under controlled breathing (20 breaths/minute) were obtained. SD1, SD2, SDRR (standard deviation of RR intervals) and RMSSD (root mean square of successive differences of RR intervals) were evaluated for 31 control group and 33 MetS subjects. RESULTS: Statistically significant lower values were observed in MetS patients in supine position (SD1: p=0.03, SD2: p=0.002, SDRR: p=0.006, RMSSD: p=0.01) and during tilt (SD2: p=0.004, SDRR: p=0.007). CONCLUSION: SD1 and SD2 combining the advantages of time and frequency domain methods, distinguish successfully between MetS and control subjects.

24 hour ambulatory blood pressure values corresponding to office blood pressure value of 130/80 mm Hg.

BACKGROUND: 24 hour ambulatory blood pressure monitoring (ABPM) values for patients who have office BP of 130/80 mm Hg have not been clearly reported. AIM: The determination of ABPM values in treated hypertensive subjects corresponding to a mean office BP of 130/80 mm Hg. METHODS: BP measurement in subjects 40-70 years old, by ABPM and mercury sphygmomanometer. The inclusion criteria were: mean office BP systolic (SBP) 128-132 mm Hg and diastolic (DBP) 78-82 mm Hg. Seventy six subjects met all study inclusion criteria. RESULTS: Mean office BP: SBP 129.5 ± 1.1 mm Hg, DBP 79.9 ± 1.3 mm Hg. Mean 24 hour BP: SBP 121.9 ± 2.0 mm Hg, DBP 73.1 ± 1.9 mm Hg. Mean awake BP: SBP 124.9 ± 2.4 mm Hg, DBP 75.5 ± 2.2 mm Hg. Mean asleep BP: SBP 109.1 ± 3.9 mm Hg, DBP 63.3 ± 4.0 mm Hg. CONCLUSIONS: The target values of ABPM identified in this study can be used in clinical practice and will contribute to risk stratification and treatment of hypertension.

Addition of spironolactone in patients with resistant arterial hypertension (ASPIRANT)--study protocol.

BACKGROUND: There is currently limited data on which drug should be used to improve blood pressure control in patients with resistant hypertension. Recent observational trials reported spironolactone as having good effects. This study is designed to assess the effect of the addition of 25 mg of spironolactone on blood pressure (BP) in patients with resistant arterial hypertension. METHODS: Patients with office systolic BP > 140 mmHg or diastolic BP > 90 mmHg despite treatment with at least 3 antihypertensive drugs including a diuretic, are enrolled in this double-blind, placebo-controlled, multicentre trial. Patients are randomly assigned to receive spironolactone or a placebo at a ratio of 1:1 by the method of simple randomisation. Our primary endpoints are to show a statistically significant difference in the fall of mean day-time systolic and diastolic BP by ambulatory blood pressure monitoring (ABPM), between the spironolactone and placebo groups, after 8 weeks of treatment. Secondary outcomes are changes of serum potassium, natrium, creatinine, body weight, casual blood pressure in office, difference in the fall of mean night-time and 24-hour ABPM BP and treatment response depending on different baseline levels of aldosterone and aldosterone/PRA ratio. DISCUSSION: If spironolactone proves effective, it might become the standard of treatment in patients with resistant arterial hypertension.

Addition of spironolactone in patients with resistant arterial hypertension (ASPIRANT): a randomized, double-blind, placebo-controlled trial.

There is currently limited data on which drug should be used to improve blood pressure (BP) control in patients with resistant hypertension. This study was designed to assess the effect of the addition of 25 mg of spironolactone on BP in patients with resistant arterial hypertension. Patients with office systolic BP >140 mm Hg or diastolic BP >90 mm Hg despite treatment with at least 3 antihypertensive drugs, including a diuretic, were enrolled in this double-blind, placebo-controlled, multicenter trial. One hundred seventeen patients were randomly assigned to receive spironolactone (n=59) or a placebo (n=58) as an add-on to their antihypertensive medication, by the method of simple randomization. Analyses were done with 111 patients (55 in the spironolactone and 56 in the placebo groups). At 8 weeks, the primary end points, a difference in mean fall of BP on daytime ambulatory BP monitoring (ABPM), between the groups was -5.4 mm Hg (95%CI -10.0; -0.8) for systolic BP (P=0.024) and -1.0 mm Hg (95% CI -4.0; 2.0) for diastolic BP (P=0.358). The APBM nighttime systolic, 24-hour ABPM systolic, and office systolic BP values were significantly decreased by spironolactone (difference of -8.6, -6.6, and -6.5 mm Hg; P=0=0.011, 0.004, and 0.011 [corrected]), whereas the fall of the respective diastolic BP values was not significant (-3.0, -1.0, and -2.5 mm Hg; P=0.079, 0.405, and 0.079). The adverse events in both groups were comparable. In conclusion, spironolactone is an effective drug for lowering systolic BP in patients with resistant arterial hypertension.

Use of a novel transfer function to reduce repolarization interval hysteresis.

BACKGROUND: Cardiac repolarization is assessed by the QT interval on the surface electrocardiogram and varies with the heart rate. Standard QT corrections (QTc) do not account for the lag in QT change following a change in heart rate (QT hysteresis). Our group has developed and tested a transfer function (TRF) model to assess the effectiveness of a dynamic model of QT/RR coupling in eliminating hysteresis. METHODS: We studied three groups: group I, healthy volunteers (n = 23, 41 ± 17 years); group II, hypertensive patients (n = 25, 45 ± 11 years); and group III, patients in a predominately paced rhythm (n = 5, 75 ± 6 years). To vary the heart rate, either exercise bicycling in the supine position (groups I and II) or manipulation of the pacemaker parameters (group III) was done. We then compared a dynamic TRF model with a model based on weighted averages of previous RR intervals. Two parameters were tested: root mean square (RMS) of the error signal between measured and computed QT and the elimination of hysteretic loops. RESULTS: TRF-based measurements eliminated hysteresis in 22/23 (95%) group I patients, 21/25 (84%) group II patients, and 4/5 (80%) group III patients. When hysteresis elimination was not complete, the QT drift that followed RR intervals was different before and after bicycling (100 ms). In these patients, the corresponding QT interval did not significantly change during this period. The TRF model was found superior to the other tested models with respect to both analyzed parameters (RMS and hysteresis elimination). CONCLUSION: The TRF model limited QT hysteresis in healthy, hypertensive, and pacemaker-dependent patients. In addition, an important finding of QT drift in patients with hypertension was identified. With further study in these and other diseased states, the TRF model may improve our ability to measure accurately cardiac repolarization and to determine arrhythmia risk.