[Suprasystolic dP/dt max an additional parameter of contractile cardiac function obtained by cuff oscillometric tracings]. / Un paramètre additionnel de fonction ventriculaire gauche dérivé du profil oscillométrique artériel.

Technological evolution allowed to record high fidelity traces that--when analysed by complex mathematical systems--may provide extremely detailed and new information about all the factors involved in the determinism of pulse wave. Suprasystolic waves, i.e. those recorded immediately before systolic pressure, may be regarded as similar to aortic pressure waves evaluated during cardiac catheterization. Suprasystolic dP/dt max was calculated from the profile of pulse wave recorded by the DynaPulse, an automatic portable non-invasive oscillometric method to simultaneously measure BP and analyse arterial waveforms, in 10 normal healthy subjects (age 37 +/- 5) and 5 subjects with ischaemic dilatative cardiomyopathy (age 41 +/- 7) whose ejection fraction--invasively assessed--was < 40%. The 24 h dP/dt max curves were analysed by parametric and non parametric tests. We found a significant difference (p < 0.001) in the average 24-h dP/dt max between healthy subjects (471 +/- 36.7 mmHg/sec) and patients with impaired cardiac function (271 +/- 54.2 mmHg/sec). The average daytime and nighttime dP/dt max values showed significantly higher values in normal subject in comparison to patients with heart failure (daytime 7.23 h: 529 +/- 74 mmHg/s versus 227 +/- 64 mmHg/s, p < 0.001; nighttime: 572 +/- 82 mmHg/s versus 202 +/- 67 mmHg/s, p < 0.001). We also found a difference in the occurrence of acrophases, at similar blood pressure value, i.e. the highest dP/dt values occurred during the night in normal subject, the opposite in ischaemic patients. Furthermore, the dP/dt max correlates only with systolic blood pressure.

Impaired vasorelaxant responses to natriuretic peptides in the stroke-prone phenotype of spontaneously hypertensive rats.

BACKGROUND: We have previously shown that a locus on rat chromosome 5, termed STR 2, co-localizes with the genes encoding atrial natriuretic and brain natriuretic peptides, and is closely linked to the development of strokes in rats of a F2 hybrid cohort obtained by crossing stroke-prone spontaneously hypertensive rats and spontaneously hypertensive rats. We also demonstrated that there are significant differences in vascular functioning that are co-segregated with stroke latency of stroke-prone spontaneously hypertensive rats. OBJECTIVE: To investigate the vascular responses to natriuretic peptides in the stroke-prone phenotype of spontaneously hypertensive rats. DESIGN AND METHODS: In view of the important vasoactive properties of natriuretic peptides, we tested the vascular responses to 10(-11)-10(-9) mol/l atrial natriuretic peptide and to 10(-11)-10(-7) mol/l brain natriuretic peptide in isolated rings of aortas and internal carotid arteries obtained from stroke-prone and stroke-resistant spontaneously hypertensive rats. The 6-week-old rats were exposed for 4 weeks either to their regular diet (n = 15 of both strains) or to the stroke-permissive Japanese-style diet (n = 14 of both strains). A group of 14 normotensive, age-matched and sex-matched Wistar-Kyoto rats was also studied. RESULTS: Systolic blood pressures in stroke-prone and stroke-resistant spontaneously hypertensive rats were similar, and were significantly higher than those in Wistar-Kyoto rats. Vascular responses to nitroglycerin, atrial natriuretic peptide, and brain natriuretic peptide in rats of the two hypertensive strains and in Wistar-Kyoto rats fed their regular diet were comparable. In contrast, the vasorelaxant responses to atrial natriuretic peptide in stroke-prone spontaneously hypertensive rats fed Japanese diet were lower both in aortas and in internal carotid arteries than were those in spontaneously hypertensive rats (both P < 0.05 by analysis of variance) and in Wistar-Kyoto rats (both P < 0.05). Similarly, vasorelaxant responses to brain natriuretic peptide were lower both in aortas and in internal carotid arteries of stroke-prone spontaneously hypertensive rats than they were in spontaneously hypertensive rats (both P < 0.05) and in Wistar-Kyoto rats (P < 0.05). The responses to nitroglycerin in the stroke-prone spontaneously hypertensive rats and spontaneously hypertensive rats fed Japanese-style diet were also similar. CONCLUSION: The vasorelaxant effects of natriuretic peptides are impaired in stroke-prone spontaneously hypertensive rats. This abnormality could play a role in the pathogenesis of stroke incidence in this hypertensive model.

Evaluation of a new ambulatory blood pressure device.

We assessed the OSCILL-IT ambulatory blood pressure (BP) recorder (FIGI sr1, Rome, Italy) according to the performance criteria set out by the British Hypertension Society (BHS) protocol. The OSCILL-IT is a portable, noninvasive recorder that uses a process that correlates systolic, mean, and diastolic areas, identified on the oscillations, to the cuff absolute pressure. According to the recommendations of BHS, a large heterogeneous population (100 subjects: 52 men aged from 19 to 79--median 44 and 48 women from 19 to 74--median 54) was recruited in order to assess accuracy and to analyze, in addition, the effects of observer agreement and BP level on the observer-device differences. With reference to BP level, we suggest also a new graphic approach. Four sets of sequential, same arm, comparative BP measurements were obtained, performed by the OSCILL-IT recorder and two skilled clinicians using a mercury column, for each subject. We used a linear combination for the statistical evaluations. We confirmed the observer agreement through the frequency distribution of BP as a function of the observer and through the differences between observers. We compared OSCILL-IT with sphygmomanometric readings: the differences were not significant. A visual inspection, with the addition of regression lines, showed that there were no variations in differences at the changing of BP level. The difference between observers and OSCILL-IT was 0.2 +/- 5.3 mm Hg and 0.2 +/- 5.8 mm Hg both for systolic BP (SBP) and diastolic BP (DBP). The level of agreement, according to BHS criteria, showed that 64% of all systolic and 70% of all diastolic readings obtained by the OSCILL-IT were within 5 mm Hg of the sphygmomanometric determinations. Therefore, the grade is C for SBP, even if 93% of SBP and 95% of DBP obtained by the OSCILL-IT were within 10 mm Hg of the sphygmomanometric determinations. These analyses demonstrate that the OSCILL-IT satisfies the accuracy parameters and the additional linear regression yields graphics more immediate.

The (dP/dt)max derived from arterial pulse waveforms during 24 h blood pressure oscillometric recording.

BACKGROUND: The modern developments in engineering allow one to record the speed at which the blood pressure rises on the advancing pulse wave front. It was possible to obtain this through the conversion of a conventional pulse from a single suprasystolic oscillation to the oscillometric envelope into its first derivative with respect to time. OBJECTIVE: The aim of this study was to report a preliminary comparison between healthy subjects and patients with heart failure as a first step towards the clinical ujse of this first derivative of a time-dependent function (dP/dt).METHODS: For 10 normal healthy subjects (aged 37 +/- 5 yhears) and five subjects with ischaemic cardiomyopathy (aged 41 +/- 7 years), whose ejection fractions (invasively assessed) wee < 40%, we evaluated six sequential oscillometric measurements of blood pressure obtain by using a Dynapulse Ps5000 (Pulse Metric, San Diego, California, USA) device, which simultaneously records blood pressure and analyses every arterial waveform. The mean and SD of (dP/dt)max for each subject were calculated, together with the relative mean distribution and the significance of the differences. RESULTS: The data show that (dP/dt)max of subjects with an impairment of cardiac function is less than normal. The mean (dP/dt)max of normalk subjects was significantly different (P < 0.05) from that of patients with ischaemic cardiomyopathy and lower than normalk ejection fractions. CONCLUSION: These preliminary results allowed us to raise the hypothesis that this parameter, being representative of the cardiac function, because many data are obtained, is extremely useful for monitoring changes during daily activities or to outline the nycthoemeral rhythm. We have to test the hypotheses that the analyses of the correlations between (dP/dt)max and other haemodynamic parameters may be used in the pathphysiological study of cardiomyopathies and that the comparison of differences in (dP/dt)max can be used in the evaluation of the effects of the treatment.

[Holter monitoring of the arterial pressure in the follow up of a group of aged patients with chronic uremia]. / Follow-up della pressione arteriosa in un gruppo di uremici anziani cronici mediante monitoraggio Holter.

The cardiovascular complication represents the principal effect of death in patients uraemics cronics. The hypertension is one of most cause; for this, the control of hypertension is one important objective in this patients. The introduction of dynamic monitoring permit to estimate the adeguatesse of hypertension control or the appearance of extradialitic hypotension. The dynamic monitoring permit to value the difference in two groups, young and elderly and to conform the hypertension therapy.

Analysis of blood pressure rhythms for drug efficacy evaluation.

This study analyzes some methods of evaluating the effects of antihypertensive drugs on blood pressure circadian rhythm. We reviewed four different approaches: hourly averages, trough-to-peak ratio, cosinor method, and Fourier series applied to the same data to prove the time course of the effects of isradipine administered once daily. A total of 141 patients of both sexes (mean age 53 years, range 30-76) with mild to moderate essential hypertension were enrolled in this multicenter trial after a 2-week placebo run-in. Treatment with isradipine SRO 5 mg/day administered between 8 and 9 AM was started. Each patient underwent ambulatory BP monitoring at the time of entry and after 6 weeks of treatment. Calculation of hourly averages showed decreases after 4 AM, and from about 8-9 AM, when the drug was administered, and the decreases practically did not vary until about 10 PM. Subsequently, the decreases became smaller and indicated reduced drug activity. However, this hypothesis no longer held after 4 AM. The trough-to-peak ratio was calculated including hourly averages after the dose divided by the lowest hourly average. Both systolic and diastolic blood pressure showed constant reduction from 3 PM (time of peak) to 11 PM. However, after 11 PM, higher trough-to-peak ratios paradoxically occurred due to a major reduction obtained with placebo, and the negative percentages just before the next dose cannot be attributed to treatment. Applying the cosinor method, maximal values were greatly underestimated, nocturnal values were overestimated, and the absolute maximum occurred in proximity to the minimum relating to postprandial dip. The generalized cosinor model, known as Fourier partial series, was always curtailed to the third harmonic. Fourier analysis was able to describe the daily trend of BP both before and after isradipine administration. We used statistical tests to determine if the differences described by the models were significant. The tests indicated significant mean level reductions after therapy and no appreciable amplitude and phase-related variations. The nocturnal and periawakening intervals, in which BP changed linearly, oscillated between 3 and 4 hours. Within these intervals BP rose by 13-16 mm Hg or fell by 14-19 mm Hg. The intervals, ranges, and speed differences were tested and were never significant. The medication tested was effective only at the mean level, the variables used to characterize the time course of its effect remaining unchanged. There was no significant phase shift of the curves, and BP rhythm was preserved.