Use of non-invasive finger blood pressure monitoring in the estimation of aortic pressure at rest and during the Mueller manoeuvre

Influence of Blood Pressure Reduction on Pulse Wave Velocity in Primary Hypertension: A Meta-Analysis and Comparison With an Acute Modulation of Transmural Pressure

BACKGROUND

Increased arterial stiffness and pulse wave velocity (PWV) of the aorta and large arteries impose adverse hemodynamic effects on the heart and other organs. Antihypertensive treatment reduces PWV, but it is unknown whether this results from an unloading of stiffer elements in the arterial wall or is due to an alternate functional or structural change that might differ according to class of antihypertensive drug.

METHODS

We performed a systematic review and meta-analysis of the effects of different antihypertensive drug classes and duration of treatment on PWV with and without adjustment for change in mean arterial blood pressure (BP; study 1) and compared this to the change in PWV after an acute change in transmural pressure, simulating an acute change in BP (study 2).

RESULTS

A total of 83 studies involving 6200 subjects were identified. For all drug classes combined, the reduction of PWV was 0.65 (95% CI, 0.46-0.83) m/s per 10 mm Hg reduction in mean arterial BP, a change similar to that induced by an acute change in transmural pressure in a group of hypertensive subjects. When adjusted for change in mean arterial BP, the reduction in PWV after treatment with beta-blockers or diuretics was less than that after treatment with angiotensin-converting enzyme inhibitors/angiotensin receptor antagonists or calcium channel antagonists.

CONCLUSIONS

Reduction in PWV after antihypertensive treatment is largely explained by the reduction in BP, but there are some BP-independent effects. These might increase over time and contribute to better outcomes over the long term, but this remains to be demonstrated in long-term clinical trials.

Blood Pressure Prediction Using Ensemble Rules during Isometric Sustained Weight Test

BACKGROUND

Predicting beat-to-beat blood pressure has several clinical applications. While most machine learning models focus on accuracy, it is necessary to build models that explain the relationships of hemodynamical parameters with blood pressure without sacrificing accuracy, especially during exercise.

OBJECTIVE

The aim of this study is to use the RuleFit model to measure the importance, interactions, and relationships among several parameters extracted from photoplethysmography (PPG) and electrocardiography (ECG) signals during a dynamic weight-bearing test (WBT) and to assess the accuracy and interpretability of the model results.

METHODS

RuleFit was applied to hemodynamical ECG and PPG parameters during rest and WBT in six healthy young subjects. The WBT involves holding a 500 g weight in the left hand for 2 min. Blood pressure is taken in the opposite arm before and during exercise thereof.

RESULTS

The root mean square error of the model residuals was 4.72 and 2.68 mmHg for systolic blood pressure and diastolic blood pressure, respectively, during rest and 4.59 and 4.01 mmHg, respectively, during the WBT. Furthermore, the blood pressure measurements appeared to be nonlinear, and interaction effects were observed. Moreover, blood pressure predictions based on PPG parameters showed a strong correlation with individual characteristics and responses to exercise.

CONCLUSION

The RuleFit model is an excellent tool to study interactions among variables for predicting blood pressure. Compared to other models, the RuleFit model showed superior performance. RuleFit can be used for predicting and interpreting relationships among predictors extracted from PPG and ECG signals.

Effects of respiratory and applied muscle tensing interventions on responses to a simulated blood draw among individuals with high needle fear

Fear of blood and needles increases risk for presyncopal symptoms. Applied muscle tension can prevent or attenuate presyncopal symptoms; however, it is not universally effective. This study examined the effects of applied muscle tension, a respiratory intervention, and a no treatment control condition, on presyncopal symptoms and cerebral oxygenation, during a simulated blood draw with individuals highly fearful of needles. Participants (n = 95) completed questionnaires, physiological monitoring, and two trials of a simulated blood draw with recovery. Presyncopal symptoms decreased across trials; however, no group differences emerged. Applied muscle tension was associated with greater cerebral oxygenation during trial two, and greater end-tidal carbon dioxide during both trials. The respiratory intervention did not differ from the no treatment control. Applied muscle tension is an intervention that can increase cerebral oxygenation and end-tidal carbon dioxide. While the respiratory intervention is promising within therapeutic settings, it was not efficacious after a brief audio training.

Altered dependence of aortic pulse wave velocity on transmural pressure in hypertension revealing structural change in the aortic wall

Aortic pulse wave velocity (aPWV), a major prognostic indicator of cardiovascular events, may be augmented in hypertension as a result of the aorta being stretched by a higher distending blood pressure or by a structural change. We used a novel technique to modulate intrathoracic pressure and thus aortic transmural pressure (TMP) to examine the variation of intrathoracic aPWV with TMP in hypertensive (n=20; mean±SD age, 52.1±15.3 years; blood pressure, 159.6±21.2/92.0±15.9 mm Hg) and normotensive (n=20; age, 55.5±11.1 years; blood pressure, 124.5±11.9/72.6±9.1 mm Hg) subjects. aPWV was measured using dual Doppler probes to insonate the right brachiocephalic artery and aorta at the level of the diaphragm. Resting aPWV was greater in hypertensive compared with normotensive subjects (897±50 cm/s versus 784±43 cm/s; P<0.05). aPWV was equal in hypertensive and normotensive subjects when measured at a TMP of 96 mm Hg. However, dependence of aPWV on TMP in normotensive subjects was greater than that in hypertensive subjects (9.6±1.6 versus 3.8±0.7 cm/s per mm Hg increase in TMP, respectively, means±SEM; P<0.01). This experimental behavior was best explained by a theoretical model incorporating strain-induced recruitment of stiffer fibers in normotensive subjects and fully recruited stiffer fibers in hypertensive subjects. These results explain previous contradictory findings with respect to isobaric aPWV in hypertensive compared with normotensive subjects. They suggest that hypertension is associated with a profound change in aortic wall mechanical properties possibly because of destruction of elastin leading to less strain-induced stiffening and predisposition to aortic dissection.

Parasympathetic versus sympathetic control of the cardiovascular system in young patients with type 1 diabetes mellitus

Autonomic neuropathy and cardiovascular dysregulation are common complications of the diabetes mellitus (DM). The aim of the study was to test the hypothesis that cardiovascular regulation is abnormal in young patients with type 1 DM. Patients with type 1 DM (17, 10 females, 7 males) aged 12.9-31.5 years (mean+/-SEM: 22.4+/-1.0 years) were investigated. The mean duration of DM was 12.4+/-1.2 years. The control group consisted of 17 healthy probands matched for sex and age. The length of R-R intervals was measured using telemetric system (VariaCardio TF4; Sima Media) where ECG signal (sampling frequency 1000 Hz) from thoracic belt was transferred into PC for further analysis. Systolic blood pressure (SBP) was monitored beat-to-beat using volume-clamp method by Finapres 2300 (Ohmeda). Spectral power in HF band of HRV (HRV-HF) was taken as an index of parasympathetic control and spectral power in LF band of systolic BPV (BPV-LF) as an index of sympathetic control. In young patients with type 1 DM significant reduction of spectral power in HF band of the heart rate variability was found, whereas no significant difference between DM group and control group was observed in spectral power in LF band of blood pressure variability. In conclusion, we found impaired parasympathetic control of heart rate in young patients with type 1 DM. No differences in blood vessels sympathetic control were detected using spectral analysis of BPV. We suggest that abnormalities in cardiac parasympathetic regulation precede impairment of blood vessels sympathetic control in young diabetics.

Portapres and differential oscillometric finger blood pressure changes during deep breathing test in the assessment of BRS index

The aim of this study was to investigate changes in the finger blood pressure during a deep breathing test (DB) and to find out whether the mean blood pressure might be used as a substitute for the systolic pressure in calculations of baroreflex sensitivity from data derived from the DB test. Continuous beat-to-beat finger pressure was recorded by the volume clamp method (Portapres model 2 monitor). In addition, the mean arterial pressure was recorded by the modified oscillometric method (UT9201 beat-to-beat monitor, University of Tartu, Estonia). Fifteen healthy volunteers, aged 25-56 years, were studied. The amplitude of respiration-linked oscillations in the Portapres systolic (Psyst) and mean blood pressure (Pmean) was 22.2 +/- 8.8 and 16.6 +/- 5.8 mmHg, respectively. There was no significant difference between the amplitudes of induced changes in Pmean recorded by the two devices: the amplitude of oscillations in the mean blood pressure recorded by the differential oscillometric monitor was 16.0 +/- 5.9 mmHg. The amplitude of oscillations in Psyst correlated significantly with the amplitude of oscillations in Pmean recorded either by Portapres or by UT9201 (r=0.95 and 0.98, respectively). The high correlation between the amplitudes of oscillations in mean and systolic blood pressure allows to conclude that mean arterial pressure changes during a DB test might be used instead of systolic pressure changes in calculation of the ratio of changes in pulse interval to changes in blood pressure, which is considered to reflect baroreflex sensitivity.

[Afterload and blood pressure amplitude in dilated cardiomyopathy]

The beat-to-beat variability of the diastolic blood pressure induces small variations in the afterload of the left ventricle. These variations influence myocardial contractility, and thus blood pressure amplitude. We assessed the interdependence of blood pressure and changes in the afterload. We continuously recorded blood pressure (duration 200 s, at rest) in 20 patients with dilated cardiomyopathy (ejection fraction 32 +/- 13%, left ventricular diameter 67 +/- 8 mm) and in 20 healthy volunteers. Interbeat intervals, diastolic pressures, systolic pressure amplitudes and mean slopes of systolic pressure amplitudes were measured. Correlation coefficients (r) were calculated to assess the interdependence of blood pressure amplitudes/mean systolic slopes and the preceding diastolic pressures/interbeat intervals, respectively. In healthy volunteers we found a strong interdependence between blood pressure amplitude and the preceding diastolic pressures (r = 0.62 +/- 0.21 and 0.47 +/- 0.22). Higher diastolic pressures were followed by higher blood pressure amplitudes, and by steeper slopes of the systolic peaks. In patients with dilated cardiomyopathy, such interdependence was significantly lower (r = 0.33 +/- 22 and r = 0.28 +/- 0.35), and in patients with severely reduced left ventricular function (ejection fraction < 32%) was only marginal (r = 0.23 +/- 0.27 and 0.21 +/- 0.44, respectively). The forces of the isovolumetric contraction necessary to initiate the ejection phase of the left ventricle depend on the afterload, i.e. on the diastolic pressure. The responses of amplitude and slope of the systolic blood pressure to small changes in the afterload make it possible to assess left ventricular contractility. The latter is impaired in dilated cardiomyopathy.

Gender differences in psychophysiological responses to speech stress among older social phobics:: congruence and incongruence between self-evaluative and cardiovascular reactions

OBJECTIVE

Evidence suggests increased cardiovascular risk and autonomic impairment among individuals with chronic anxiety. Little attention, however, has been paid to the anxiety disorder of social phobia despite its high prevalence. Additionally, gender- and age-related cardiovascular profiles have not been examined in relation to social phobia. This study investigated cardiovascular responses to a socially threatening situation among older men and women with social phobia and control subjects.

METHODS

Thirty subjects with social phobia and 30 control subjects (mean age = 65 years) were assessed during baseline, paced breathing, speech preparation, and speech presentation. Electrocardiographic variables, blood pressure, respiration, and emotional state (self-reported) were monitored. Hemodynamic variables included heart rate, blood pressure, cardiac output, and systemic vascular resistance; autonomic measures were respiratory sinus arrhythmia and baroreflex sensitivity, both markers of cardiac vagal control, and 0.10-Hz systolic blood pressure variability, an index of sympathetic vasomotor tone.

RESULTS

Subjects with social phobia, in contrast to nonanxious control subjects, manifested more anxiety, embarrassment, and somatic complaints in response to stress; however, physiological measures generally did not distinguish groups. Interaction effects indicated that socially phobic women were hyperresponsive to the stressor with respect to self-reported, hemodynamic, and autonomic parameters. Socially phobic men manifested no physiological differences in comparison with control subjects, but they reported more psychological and somatic complaints.

CONCLUSIONS

Gender differences in subjective and physiological responses to a socially threatening situation indicate congruence between perceived social anxiety and physiological responses in older women but not men. We found no evidence of impaired cardiovascular autonomic regulation among socially phobic men despite other reports that phobically anxious men are at greater cardiovascular risk.

Evaluation of impaired dynamic cerebral autoregulation by the Mueller manoeuvre

Arterial blood pressure (ABP) shows polyphasic changes during the Mueller manoeuvre (voluntary negative intrathoracic pressure). The aim of the present study was to investigate (1) whether these changes could be applied to detect impaired dynamic cerebral autoregulation (dCA) in carotid stenosis and (2) whether the degree of indicated impairment correlates with transfer function phase as another current measure for dCA (deep breathing method) and CO2-reactivity. We examined 13 patients with severe unilateral carotid artery stenosis and 16 age-matched controls during 15-s Mueller manoeuvres (MM) at -30 mmHg using bilateral transcranial Doppler sonography and non-invasive ABP recordings (Finapres, 2300, Ohmeda, Englewood, CO, USA). After an initial biphasic oscillation, cerebral blood flow velocity (CBFV) and ABP decreased to below baseline. CBFV reincreased in controls and on contralateral sides in patients 6.0 s (3.8-9.5 s, median and range) after the onset of the decrease, despite a further fall in ABP. CBFV over the affected side revealed a significantly delayed reincrease (8.0 (5.6-10.3) s; P<0.01) combined with a relatively flat and inertial amplitude behaviour. An applied autoregulation index derived from the MM (mROR), phase shift and CO2-reactivity were severely reduced on the affected side in patients (P<0.01). Reduction of the mROR correlated significantly with reduction of phase shift (r=0.69; P=0.002) and CO2-reactivity (r=0.78; P=0.002). In conclusion, the different cerebral haemodynamic pattern during the MM in patients is likely to reflect impaired dCA. The degree of indicated impairment correlates with that of transfer function phase and CO2-reactivity. Therefore, the MM represents a convenient method for grading of compromised cerebral haemodynamics in patients with carotid artery stenosis.

Nasal continuous positive airway pressure reduces sleep-induced blood pressure increments in preeclampsia

Preeclampsia is the predominant cause of admissions to neonatal intensive care. The diurnal blood pressure pattern is flattened or reversed in preeclampsia. We hypothesized that snoring and partial upper airway obstruction contribute to nocturnal rises in blood pressure. We tested this hypothesis by controlling sleep- induced upper airway flow limitation and snoring with nasal positive pressure. Eleven women with preeclampsia underwent two consecutive polygraphic sleep studies with simultaneous beat-to-beat blood pressure monitoring. Average blood pressure for the night overall and in each sleep stage was calculated. Sleep architecture was similar on the two study nights. Sleep-induced partial upper airway flow limitation occurred in all patients in the initial study. Autosetting nasal continuous positive airway pressure (CPAP) applied at a mean maximal pressure of 6 +/- 1 cm H(2)O eliminated flow limitation throughout sleep on the treatment night. Blood pressure was markedly reduced on the treatment night [(128 +/- 3)/(73 +/- 3)] when compared with the initial nontreatment study night [(146 +/- 6)/(92 +/- 4)], p = (0.007)/(0.002). We conclude that partial upper airway obstruction during sleep in women with preeclampsia is associated with increments in blood pressure, which can be eliminated with the use of nasal CPAP.

Cerebral haemodynamics during the Mueller manoeuvre in humans

Voluntary negative intra-thoracic pressure (Mueller manoeuvre) is known to reduce arterial blood pressure (ABP). To investigate changes in cerebral blood flow velocity (CBFV) during 15 s Mueller manoeuvres at -30 mmHg intra-thoracic pressure, 27 young (aged 21-31 years, group A) and 11 older (52-64 years, group B) healthy adults were studied using transcranial Doppler and non-invasive ABP measurement (Finapres). After closely following the initial ABP drop, CBFV showed an overshoot during temporary recovery of ABP. Then ABP and CBFV decreased significantly to below baseline. While ABP declined further until the end of the manoeuvre, CBFV increased in group A 4.7 s (2.4-8.5) (median and range) and in group B 5.7 s (4. 1-7.2) after the onset of the CBFV decrease. Critical closing pressure (CCP), calculated for each cardiac cycle from the dynamic pressure-flow relationship (DPFR), indicated a reduction of intra-cranial pressure during the first half of the strain. DPFR-related estimation of cerebrovascular resistance provided a more physiological response than the conventional cerebrovascular resistance quotient ABP/CBFV, and decreased about 1.5 s before the observed CBFV increase. A modification of the previously described dynamic auto-regulation index ROR correlated significantly with CO2 reactivity values (r=0.61, P=0.001). In conclusion, changes in CBFV during Mueller manoeuvres are likely to reflect dynamic cerebral auto-regulation and may provide an estimate of dynamic cerebral auto-regulation capacity. In older adults, the maximal dynamic auto-regulatory response seems to be unchanged, but the onset of reaction is slightly delayed.

Entrainment of blood pressure and heart rate oscillations by periodic breathing

Cheyne-Stokes respiration (CSR) is a form of periodic breathing associated with periodic oscillations in blood pressure (BP) and heart rate (HR), which have been attributed to hypoxia and arousals from sleep. We hypothesized that periodic alterations in ventilation alone would promote oscillations in BP and HR. Seven healthy, wakeful subjects breathed in three patterns, as follows: (1) regular breathing (RB); (2) periodic breathing with three (PB3: cycle frequency = 0.035 Hz) augmented breaths alternating with 20-s apneas; and (3) periodic breathing with five (PB5: cycle frequency = 0.030 Hz) augmented breaths alternating with 20-s apneas. SaO2 remained above 95% throughout. During periodic breathing, peaks in BP and HR occurred during the ventilatory period and troughs occurred during apnea. The magnitudes of systolic BP oscillations increased significantly from RB (14 +/- 5 mm Hg) to PB3 (20 +/- 4 mm Hg) and PB5 (25 +/- 7 mm Hg; p < 0.005). HR oscillations also increased from regular breathing (13 +/- 6.0 beats/min) to PB3 (20.2 +/- 2.3 beats/min) and PB5 (20.2 +/- 4.7 beats/ min; p < 0.01). Spectral analysis showed that during periodic breathing there were discrete peaks in the spectral power of ventilation, BP, and R-wave-to-R-wave interval at the periodic breathing cycle frequencies. We conclude that oscillations in ventilation occurring during periodic breathing can amplify and entrain oscillations in BP and HR in the absence of hypoxia or arousals from sleep.

Magnitude and time course of hemodynamic responses to Mueller maneuvers in patients with congestive heart failure

To simulate the immediate hemodynamic effect of negative intrathoracic pressure during obstructive apneas in congestive heart failure (CHF), without inducing confounding factors such as hypoxia and arousals from sleep, eight awake patients performed, at random, 15-s Mueller maneuvers (MM) at target intrathoracic pressures of -20 (MM -20) and -40 cmH2O (MM -40), confirmed by esophageal pressure, and 15-s breath holds, as apneic time controls. Compared with quiet breathing, at baseline, before these interventions, the immediate effects [first 5 cardiac cycles (SD), P values refer to MM -40 compared with breath holds] of apnea, MM -20, and MM -40 were, for left ventricular (LV) systolic transmural pressure (Ptm), 1.0 +/- 1. 9, 7.2 +/- 3.5, and 11.3 +/- 6.8 mmHg (P < 0.01); for systolic blood pressure (SBP), 2.9 +/- 2.6, -5.5 +/- 3.4, and -12.1 +/- 6.8 mmHg (P < 0.01); and for stroke volume (SV) index, 0.4 +/- 2.8, -4.1 +/- 2.8, and -6.9 +/- 2.3 ml/m2 (P < 0.001), respectively. Corresponding values over the last five cardiac cycles were for LVPtm 6.4 +/- 4.4, 5.4 +/- 6.6, and -4.5 +/- 9.1 mmHg (P < 0.01); for SBP 6.9 +/- 4.2, -8.2 +/- 7.7, and -24.2 +/- 6.9 mmHg (P < 0.01); and for SV index -0. 4 +/- 2.1, -5.2 +/- 2.8, and -9.2 +/- 4.8 ml/m2 (P < 0.001), respectively. Thus, in CHF patients, the initial hemodynamic response to the generation of negative intrathoracic pressure includes an immediate increase in LV afterload and an abrupt fall in SV. The magnitude of response is proportional to the intensity of the MM stimulus. By the end of a 15-s MM -40, LVPtm falls below baseline values, yet SV and SBP do not recover. Thus, when -40 cmH2O intrathoracic pressure is sustained, additional mechanisms, such as a drop in LV preload due to ventricular interaction, are engaged, further reducing SV. The net effect of MM -40 was a 33% reduction in SV index (from 27 to 18 ml/min2), and a 21% reduction in SBP (from 121 to 96 mmHg). Obstructive apneas can have adverse effects on systemic and, possibly, coronary perfusion in CHF through dynamic mechanisms that are both stimulus and time dependent.

Blood pressure responses to mental stress in emotionally defensive patients with stable coronary artery disease

Emotional defensiveness, defined by concealment of both negative emotions and personal vulnerability, was substantially and consistently correlated with the magnitude of blood pressure reactions to 2 types of mental stress among coronary patients, independently of clinical status. Given recent studies denoting stress-related blood pressure surges as triggers of dangerous cardiovascular events, exaggerated vasomotor reactions among defensive patients may be of clinical significance.

Incremental bias in Finapres estimation of baseline blood pressure levels over time

Finapres finger blood pressure monitoring appears to provide a reliable alternative to intra-arterial blood pressure measurement under many circumstances. However, few studies have focused on the limitations of Finapres assessment. In a previous pilot investigation, we observed that Finapres pressure following mental stressors failed to return to initial resting levels. Our objectives in the present study were to (1) replicate earlier findings, (2) examine whether local changes in the measured finger were responsible for the observed drift, and (3) test a method to facilitate the return of pressure to systemic baseline levels. We studied two groups of healthy subjects who underwent a protocol consisting of two mental stressors preceded and followed by baseline periods. In the control group, the Finapres continuously monitored pressure on a single finger for the entire protocol. The intervention group periodically had the Finapres cuff removed and the measured finger exercised to prevent local changes that might influence Finapres estimation of blood pressure. Comparisons indicated a group x baseline interaction effect for systolic and diastolic pressures (P < .0004 and P < .003, respectively). The group with the exercise intervention showed much greater recover during the final baseline than the control group. Recovery of pressures in the control group but not the intervention group was inversely related to the stress level of blood pressure (r = .86, P < .0002), indicating a relationship between blood pressure rise and the degree of distortion of subsequent baseline values. On the basis of our results, we propose that in prolonged protocols, the measurement finger be exercised to facilitate accurate measurements of finger pressure with the Finapres.

Cardiac vagal control and dynamic responses to psychological stress among patients with coronary artery disease

Two groups of patients with coronary artery disease who differed in level of cardiac vagal control were compared in their cardiovascular responses to psychological stress. Patients with lower vagal control manifested increased reactions in diastolic blood pressure and rate-pressure product to mental stress and tended to have greater systemic vasoconstriction.

Continuous non-invasive measurement of mean blood pressure in fingers by volume-clamp and differential oscillometric method

The present study compares two different methods for non-invasive beat-to-beat finger arterial blood pressure monitoring. The measurements using the volume clamp method (FINAPRES, Ohmeda, USA) were compared with measurements applying the differential oscillometric method (UT9201 device, University of Tartu). 13 healthy volunteers were studied at rest, during head-up tilt (HUT) and during deep breathing (DB) with a fixed rate of 6 breaths/min. Blood pressure was recorded from adjacent fingers of the right hand. 150 pairs of mean blood pressure values in each subject were included for statistical evaluation. No systematic differences between the two methods were found. The difference between values (FINAPRES-UT9201) at rest was -1.1 mmHg (SD 5.5), during HUT 0.5 mmHg (SD 6.9) and during DB -3.6 mmHg (SD 7.7). The insignificant differences between the results obtained by the two independent methods allow us to conclude that both methods give reliable data on finger mean arterial pressure.

Heart rate and blood pressure variability and baroreflex sensitivity in hypercholesterolaemia

To evaluate cardiovascular autonomic function in hypercholesterolaemia, we studied 16 age-matched pairs of healthy males with elevated serum cholesterol and normocholesterolaemic control subjects (altogether 37 men, aged 27-56 years). We used power spectral analysis to measure short-term heart rate and blood pressure variability, and the phenylephrine method to determine baroreceptor reflex sensitivity. The mean (SD) serum cholesterol concentration was 6.43 (1.22) among the hypercholesterolaemic subjects and 4.30 (0.44) mmol/l among the control men (P < 0.001). The respective low density lipoprotein (LDL) cholesterol concentrations were 4.44 (1.22) and 2.46 (0.38) mmol/l (P < 0.001). The total power (0.0-0.5 Hz) of heart rate and blood pressure variability did not differ between the groups, and neither did the high-frequency (0.15-0.5 Hz) and medium-frequency components (0.07-0.15 Hz). Mean (SD) baroreceptor reflex sensitivity was 18.1 (7.9) in hypercholesterolaemic and 19.4 (6.3) ms mmHg-1 in normocholesterolaemic subjects (P = 0.352). when all the subjects were analysed together, we observed a slight inverse trend between serum LDL cholesterol and baroreceptor reflex sensitivity (r = -0.235, P = 0.161). In conclusion, hypercholesterolaemia does not alter autonomic neural regulation of the cardiovascular system as assessed heart rate and blood pressure variability and baroreflex sensitivity.

Simultaneous invasive and noninvasive evaluations of baroreflex sensitivity with bolus phenylephrine technique

Estimation of baroreflex sensitivity (BRS) is receiving increasing attention in clinical and experimental cardiology. Until recently, in most studies BRS has been assessed on the basis of invasive blood pressure measurement, which limits its use in large-scale studies and in clinical practice. The development of continuous noninvasive blood pressure monitoring has made it possible to assess BRS noninvasively. We compared central invasive and peripheral noninvasive techniques in the assessment of BRS during cardiac catheterization in 40 patients with possible coronary artery disease. The correlation between noninvasive and invasive BRS was high (r = 0.92; p < 0.001). However, the noninvasive method resulted in significantly higher BRS values than did the invasive method (7.1 +/- 6.5 msec/mm Hg vs 5.1 +/- 4.3 msec/mm Hg, respectively; p < 0.001) because of the smaller increase in systolic blood pressure after phenylephrine injection by the noninvasive technique than by the invasive technique (18.9 +/- 6.8 mm Hg vs 25.2 +/- 7.8 mm Hg, respectively; p < 0.01). The difference between noninvasive and invasive BRS correlated positively with invasive BRS (r = 0.54; p < 0.001) and inversely with age (r = -0.39; p < 0.01) and resting systolic blood pressure (r = -0.30, p < 0.05). A noninvasive BRS value of < 4.0 ms/mm Hg showed a sensitivity of 94%, a specificity of 91%, and an accuracy of 93% in identifying cases of reduced invasive BRS (< 3.0 msec/mm Hg). Our findings encourage the use of finger-cuff method in the assessment of BRS. However, noninvasive BRS values were slightly but significantly higher than invasive BRS values, a difference that should be taken into account when BRS is measured by the noninvasive approach.

Continuous non-invasive finger blood pressure monitoring in children

We evaluated the performance of continuous non-invasive finger arterial pressure measurement using the volume-clamp technique (Finapres). This study was designed to compare finger arterial pressure with brachial blood pressure estimated by the auscultatory method in 217 children (90 boys and 127 girls) aged 4-16 years and in 38 adults (aged 18-45 years). Finger and brachial artery pressure readings were obtained consecutively from the ipsilateral side in the supine position. Finger arterial pressure waveforms were recorded in all children except 4 with small and thin fingers. There was good agreement for systolic pressure with only a slight underestimation of 1.9 mmHg and 5.1 mmHg lower for diastolic pressure. This difference most probably reflects inaccuracy of the auscultatory cuff method rather than an error in the Finapres. There was large inter-individual variability in Finapres recordings which might be due to differences in vasomotor tone, as demonstrated by systolic amplification in 5 patients with anorexia. However, Finapres showed a small within-subject variability (3.8 mmHg for systolic and 4.1 mmHg for diastolic pressure) determined in 5 patients during phenylephrine infusion, and as good reproducibility as the auscultatory method. These results suggest that finger arterial pressure measurement in children older than 6 years of age has similar accuracy as that in adults, and that this method is useful for clinical applications in children, especially for the non-invasive evaluation of autonomic control and cardiovascular reflexes involving transient and rapid blood pressure changes.

Correlates of left ventricular mass in a population sample aged 36 to 37 years. Focus on lifestyle and salt intake

BACKGROUND

Echocardiographically determined left ventricular (LV) mass predicts adverse cardiovascular events in the general population. We have assessed the correlates of LV mass in a population-based study focusing on lifestyle and salt intake.

METHODS AND RESULTS

A random sample of 120 persons born in 1954 was invited; 93 (42 men) entered the study. The subjects' physical activity and alcohol, tobacco, and coffee consumption were quantified by 2-month dairy follow-up, and sodium intake was quantified by 7-day food records. Blood pressure was averaged for casual cuff measurements made 2 months apart. LV mass was determined by M-mode echocardiography, and stroke volume was determined by Doppler. Hematocrit and serum insulin were measured. In multiple linear regression analysis, LV mass was related positively and independently (P < .05) to body weight, systolic blood pressure, stroke volume, sodium intake, hematocrit, and energy expenditure in leisure-time physical activity. Additional analyses showed that the relation of LV mass to daily sodium intake depended on blood pressure (P < .001 for the interaction); the multiple regression coefficient (+/- SE) was 0.41 +/- 0.11 g.mEq-1 x d-1 (P = .001) in subjects with systolic blood pressure above the population median but statistically nonsignificant (-0.15 +/- 0.10 g.mEq-1 x d-1) in those with lower blood pressure. LV mass was clearly elevated only in persons with both blood pressure and sodium intake above the population medians.

CONCLUSIONS

Body weight, blood pressure, stroke volume, sodium intake, physical activity, and hematocrit are independent predictors of LV mass among unselected persons aged 36 to 37 years. The synergistic interaction of dietary salt with blood pressure suggests that high sodium intake may sensitize the heart to the hypertrophic stimulus of pressure load. Prospective studies are needed to confirm these cross-sectional associations.

Prevalence and predictors of audible physiological third heart sound in a population sample aged 36 to 37 years

BACKGROUND

A physiological third heart sound (S3) is common in youth but allegedly very rare after the age of 40 years. The mechanism of its disappearance is not known. The aim of this work was to study the prevalence and predictors of physiological S3 in a population-based sample of persons approaching 40 years of age.

METHODS AND RESULTS

A random sample of 120 persons born in 1954 was invited; 93 (42 men) entered the study. Their physical activity, alcohol and tobacco consumption, and salt intake were quantified by diary follow-up. The presence of an S3 was determined by auscultation and confirmed by phonocardiography. Left ventricular (LV) size, mass, and systolic function were assessed by M-mode echocardiography and LV filling by Doppler velocimetry of transmitral flow. An audible S3 was detected in 22 subjects, 1 of whom had heart disease. The prevalence of physiological S3 was 23.1%. Subjects with physiological S3 had a lower body mass index (22.3 +/- 2.8 versus 24.6 +/- 4.1 kg/m2 [mean +/- SD], P = .005), lower heart rate (63 +/- 7 versus 68 +/- 10 beats per minute, P = .015), higher peak early diastolic transmitral velocity (67 +/- 10 versus 58 +/- 8 cm/s, P = .002), and higher acceleration of early diastolic velocity (717 +/- 148 versus 622 +/- 122 cm/s2, P = .012) than those without S3. No differences were noted in the lifestyle characteristics, blood pressure, or LV mass and systolic function. Body mass index and peak early diastolic transmitral velocity were independent predictors of physiological S3 in logistic regression analysis.

CONCLUSIONS

Nearly one fourth of persons approaching their forties still have an audible physiological S3. The presence of S3 is predicted by leanness and a high early diastolic LV inflow velocity; the disappearance of S3 is unlikely to be secondary to increasing blood pressure and relative LV hypertrophy, as is widely presented, but reflects a more primary age-related alteration of LV early diastolic function.

Short-term heart rate variability and factors modifying the risk of coronary artery disease in a population sample

Heart rate (HR) variability is impaired in chronic coronary artery disease (CAD), but the mechanism is not fully resolved. This study was aimed at assessing whether HR variability is influenced by the risk factors of CAD. Of a random sample of 120 subjects born in 1954, 88 (41 men and 47 women) could be included in the analyses. No subject had clinical heart disease. The subjects' physical activity, alcohol consumption and smoking were quantified by 2-month diary follow-up. Serum lipids and insulin were measured. The tests of HR variability included power spectral analysis and calculation of the root-mean-square difference of RR intervals at rest under controlled respiration. HR variability indexes were asymmetrically distributed and strongly HR-dependent, and therefore, all statistical tests were performed on log-transformed data adjusted to the population mean HR. Multiple regression analyses showed independent inverse relations between the root-mean-square RR difference and low-density lipoprotein (LDL) cholesterol (beta = -0.22; p = 0.008), and between the total RR-interval power and LDL cholesterol (beta = -0.25; p = 0.007), as well as smoking (beta = -0.19; p = 0.035). In women, alcohol use influenced the RR-interval root-mean-square difference (beta = 0.31; p = 0.015), total power (beta = 0.33; p = 0.017) and high-frequency power (beta = 0.26; p = 0.056). It is concluded that short-term HR variability is related inversely to LDL cholesterol and smoking in the population, and directly to alcohol use in women.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of temperature on finger artery pressure evaluated by volume clamp technique

We examined the effect of temperature on digital arterial blood pressure obtained by continuous beat-to-beat non-invasive monitoring with a volume-clamp technique (Finapres). In 10 normal volunteers and 13 patients with symptoms of vasospasm, digital pressure and brachial artery pressure (cuff method) was simultaneously recorded in control conditions at room temperature, during body cooling, finger heating, and truncal heating. In the control condition digital systolic blood pressure was significantly higher (16.1 +/- 14.2 mmHg) than brachial systolic pressure. The augmentation of digital systolic pressure correlated inversely with finger tip temperature. Diastolic and mean arterial pressure did not differ significantly between the two methods. Body cooling augmented the systolic finger-arm gradient while truncal heating and finger heating had the opposite effect. Finger heating reduced systolic augmentation without changing the mean and diastolic blood pressure. Similar changes were also observed in the patients with vasospasm except in one case with a pronounced Raynaud syndrome where digital blood pressure was lower than brachial artery pressure. We conclude that augmentation of finger systolic pressure seems to be dependent on local vasoconstriction of A/V shunts and that finger heating may be a useful procedure to improve the reliability of Finapres readings.