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Biomedical subjects

D A Duprez

Publications and source records attributed to D A Duprez.

31 records · Page 2Linked to original sources
PubMed1993

24 hour ambulatory blood pressure variability and cardiac parasympathetic function 2 and 6 weeks after acute myocardial infarction.

The aim of the study was to assess non-invasively circadian blood pressure rhythm as well as the influence of parasympathetic function 2 and 6 weeks after acute myocardial infarction treated with beta-blocking agents. Twenty-four patients with uncomplicated first myocardial infarction, and aged less than 60 years, underwent ambulatory blood pressure recordings every 15 min during the day (0900-2100 h) and every 30 min during the night (2100-0900 h), 2 and 6 weeks after infarction. The deep breathing test (6 breaths/min) was performed on each occasion. Normal circadian blood pressure rhythm was maintained with a nocturnal decline of 10 to 15%. Both for systolic and diastolic blood pressure a moderate increase was obtained after 6 weeks (107.8 +/- 9.2 mmHg vs. 111.8 +/- 10.3 mmHg; NS and 64.9 +/- 4.5 mmHg vs. 68.8 +/- 6.5 mmHg; p < 0.05). The respective blood pressure variations were significantly higher at that time (10.0 +/- 2.4 mmHg vs. 13.6 +/- 4.2 mmHg; p < 0.001 and 7.9 +/- 1.7 mmHg vs. 11.7 +/- 3.5 mmHg, p < 0.001). There was a close correlation (r = 0.60, p < 0.005) between 24-h diastolic blood pressure variability and the results of the parasympathetic function test (deep breathing) 2 weeks after infarction. We conclude that the circadian blood pressure rhythm persists after acute myocardial infarction. The correlation between blood pressure variability and parasympathetic function early after infarction suggests a role for vagal control in post-infarction blood pressure variability.

Acute Disease↗
PubMed1993

Autonomic imbalance in the recovery period after myocardial infarction.

The aim of the study was to evaluate the responses to autonomic function tests during the healing period of myocardial infarction (AMI). In 24 patients, at 2 and 6 weeks after the acute event, Valsalva manoeuvre, deep breathing at 6 breaths per min, isometric handgrip and cold pressor tests were performed. Responses of arterial blood pressure (BP) and heart rate (HR) were measured. At 2 weeks post AMI a significant decrease in parasympathetic tone was noted: HR reduction during deep breathing: 18.5 +/- 5.7 beats.min-1 for controls vs 9.7 +/- 2.6 beats.min-1 for AMI, P < 0.001. Systolic BP response to handgrip and cold pressor test was only slightly (non significantly) increased: 30.6 +/- 12.9 mmHg (controls) vs 40.0 +/- 20.5 mmHg (AMI) for the handgrip test and 13.8 +/- 8.1 mmHg vs 18.0 +/- 10.1 mmHg respectively for the cold pressor test. At 6 weeks post AMI, the response to the deep breathing test (15.9 +/- 5.6 beats.min-1) no longer significantly differed from that in controls. In contrast, the sympathetic stressor tests showed a significant increase in systolic BP response: 63.8 +/- 21.9 mmHg, P < 0.001 and 26.1 +/- 14.9 mmHg, P < 0.05, respectively for the handgrip and cold pressor tests. It appeared that infarct localization had no effect on autonomic function tests. There is evidence of autonomic imbalance both at 2 and 6 weeks after AMI, with a rapid but transient decrease in vagal activity and enhancement of orthosympathetic nervous tone; this was markedly more pronounced at 6 weeks post AMI despite treatment with beta-blocking agents in all patients.

Adult↗
PubMed1993

Haptoglobin polymorphism and complications in established essential arterial hypertension.

OBJECTIVE: Salt sensitivity and the magnitude of systolic blood pressure have been linked to haptoglobin (Hp) polymorphism in normotensives. The aim of the present study was to investigate the indices of hypertension, the severity of complications and the occurrence of coronary and peripheral artery disease for the various haptoglobin phenotypes and their relation to the therapeutic needs (number and class of drugs) of established arterial hypertensives. DESIGN: Haptoglobin polymorphism was studied in 302 Caucasians with established essential arterial hypertension who had been treated for at least 1 year. METHODS: Haptoglobin polymorphism was studied using starch-gel electrophoresis of haemoglobin-supplemented serum. RESULTS: The relative allele frequencies of Hp 1 and Hp 2 (0.036 and 0.640, respectively) in established hypertensives were comparable with those of the control population. Logistic regression analysis confirmed that Hp 2-2 contributes to the therapeutic needs in hypertension. The most important factors determining therapeutic needs were coronary artery disease, Hp 2-2 phenotype, body mass index (BMI) and left ventricular hypertrophy. Although no contributive effect of serum haptoglobin concentration could be derived from the logistic regression approach, analysis of serum haptoglobin concentration demonstrated a concentration-related effect on therapeutic needs for the Hp 2-2 phenotype only. CONCLUSIONS: The present study suggests that hypertensives with an Hp 2-2 phenotype need more complex combinations of antihypertensive drugs to reduce blood pressure to the same level. The hypertensive patient carrying Hp 2-2 is more likely to accumulate atherosclerotic lesions of the coronary or peripheral arteries, despite comparable lipid levels, smoking habits and BMI. Hp 1-1 patients are characterized by a younger age at diagnosis and a lower complication rate. In view of the greater therapeutic needs and the higher complication rate, Hp 2-2 hypertensives need more careful follow-up.

Aged↗
PubMed1993

Exercise performance and diastolic filling in essential hypertension.

OBJECTIVES: To investigate the relationship between arterial blood pressure, left ventricular mass, diastolic filling and maximal exercise capacity in patients with newly diagnosed essential hypertension. DESIGN: Asymptomatic untreated patients with office blood pressure > 140/90 mmHg were studied prospectively after exclusion of associated disease. METHODS: Twenty consecutive white patients (14 male, 6 female; age 43 +/- 12 years) with office blood pressure 164 +/- 23/103 +/- 10 mmHg, mean 24-h ambulatory blood pressure 142 +/- 25/89 +/- 15 mmHg and normal systolic cardiac function underwent an echocardiographic examination to determine left ventricular mass and diastolic filling parameters and performed a bicycle ergometer test to determine maximal voluntary exercise capacity. RESULTS: In single regression analysis exercise time and maximal oxygen uptake were related to sex and age. A multiple regression showed that only age was related to exercise capacity, however. On subgroup analysis of male patients between 30 and 50 years (n = 10), exercise time (659 +/- 134 s) was significantly inversely related to mean 24-h ambulatory diastolic blood pressure (92 +/- 11 mmHg) (r = -0.67; p = 0.03) and positively to diastolic filling expressed as ratio of peak early to peak atrial filling velocity (Emax/Amax ratio; 1.34 +/- 0.40) (r = 0.65; p = 0.04) or as ratio of velocity time integral (VTI) of early filling phase to VTI of atrial filling phase (VTIE/VTIA ratio; 1.94 +/- 0.72) (r = 0.02). Maximal oxygen consumption (22.3 +/- 4.1 ml/kg/min) was significantly inversely correlated with mean 24-h ambulatory diastolic blood pressure (r = -0.67; p = 0.03), mean 24-h ambulatory systolic blood pressure (147 +/- 25 mmHg) (r = -0.82; p < 0.01), left ventricular mass (312 +/- 143 g) (r = -0.86; p < 0.01), left ventricular mass index (135 +/- 41 g/m2) (r = -0.76, p = 0.01) and positively with diastolic filling expressed as Emax/Amax ratio (r = 0.71; p = 0.02) or as VTIE/VTIA ratio (r = 0.70; p = 0.02). CONCLUSION: This study shows the important interrelation between blood pressure, cardiac mass, diastolic filling and exercise capacity. High blood pressure entrains a larger cardiac mass but slows cardiac filling and decreases exercise capacity.

Adult↗
PubMed1993

Skin capillary erythrocyte velocity and mean 24 hour ambulatory blood pressure level.

This study aimed to examine the relation between capillary dynamics and parameters of ambulatory blood pressure (BP) recordings in a range covering very low to high BP (mean arterial BP: 70-140 mm Hg). A total number of 45 subjects underwent a 24 h ambulatory BP recording at 30 min intervals. The subjects did not receive any medication. Then the subjects were subdivided in 5 categories along their mean 24 h arterial BP values < 80, 80-90, 91-105, 106-115, > 115 mm Hg. Nailfold capillaries were examined at the level of the fourth finger using TV-microscopy. Our results demonstrate that erythrocyte velocity could be maintained relatively constant (mean velocities 700-800 microns/s) within the ambulatory mean arterial blood pressure range of 80-115 mm Hg. For very low and high blood pressures significant decreases (p < 0.01) were noted. Using office mean arterial blood pressure comparable results were obtained.

Blood Flow Velocity↗
PubMed1992

Venous responses to rhythmic exercise in contralateral forearm and calf.

Ten normal healthy subjects performed a rhythmic handgrip at 30% MVC (maximal voluntary contraction) with and without arterial occlusion of the same limb. Contralateral forearm and calf venous capacitance were simultaneously measured by venous occlusion plethysmography. During rhythmic handgrip at 30% MVC contralateral venous capacitance decreased by -7.17% in the forearm and by -5.14% in the calf. With arterial occlusion the decreases in venous capacitance were even more pronounced: contralateral forearm -14.4% and calf -13.1%. In a second set of experiments (n = 5) rhythmic handgrip at 30% MVC with arrest of the forearm circulation 5 s prior to the cessation of contraction was applied to examine the influence of chemically sensitive metaboreceptors per se on the evoked limb venoconstriction. During the postexercise arterial occlusion forearm venous volume decreased further to -30.6% whereas calf venous volume increased slightly but remained below the control value. After the cessation of the arterial occlusion both forearm and calf capacitance returned to baseline values. Thus, this study provided evidence that as well as a chemically generated reflex arising from the working muscle, central command was found to be involved in the increase in venomotor tone in the nonexercising limbs during rhythmic handgrip at 30% MVC.

Adult↗
PubMed1991

Influence of the arterial blood pressure and nonhemodynamic factors on left ventricular hypertrophy in moderate essential hypertension.

In a group of 36 untreated patients with mild to moderate essential hypertension (office systolic and diastolic blood pressures (BPs) 160 +/- 3.4 and 102 +/- 1.5 mm Hg, respectively), a 24-hour ambulatory BP monitoring and determination of left ventricular (LV) mass index according to the formula of Devereux were performed. After an overnight fast, blood samples were taken for the determination of serum aldosterone, plasma renin activity and serum parathyroid hormone. Urinary catecholamines were sampled for 24 hours. LV mass index (143.7 +/- 8 g/m2) did not correlate significantly either with office systolic or diastolic BP. The correlation of LV mass index with mean 24-hour systolic BP (145 +/- 3 mm Hg) was statistically significant: r = 0.395, p = 0.026. However, the best correlation was obtained with mean 24-hour diastolic BP (90 +/- 3 mm Hg) with r = 0.500 (p = 0.004). Urinary catecholamines were not correlated with LV mass index. LV mass index correlated significantly with plasma renin activity (r = 0.346, p = 0.050), and aldosterone (r = 0.559, p = 0.001). There was a very significant correlation between LV mass index and parathyroid hormone (r = 0.719, p = 0.00001) even after adjustment for mean 24-hour systolic and diastolic BPs. These results clearly demonstrate that ambulatory BP determinants but not office BP parameters are well correlated with LV hypertrophy in essential hypertension. Nonhemodynamic factors are important determinants of LV mass as well. Besides the renin-angiotensin-aldosterone system, parathyroid hormone appears to play an important role in cardiac hypertrophy.

Adult↗
PubMed1989

Circulatory changes in muscle and skin arteries in orthostatic hypotension and constitutional hypotension.

It is not known whether there are vascular changes in the peripheral circulation of patients with orthostatic hypotension and patients with constitutional hypotension. Therefore, blood flow was studied simultaneously at the calf (mainly muscle circulation) and at the finger (mainly finger circulation) with ECG-triggered venous occlusion plethysmography. Calf and finger blood flow were measured for 20 min at rest and during reactive hyperaemia due to an arterial occlusion for 3 min. Vascular resistance was calculated from the blood flow and arterial blood pressure. In orthostatic hypotension there is a decreased vasodilator capacity of the calf resistance vessels and not of the finger resistance vessels. In constitutional hypotension there is a decreased vasodilator capacity of the calf and finger resistance vessels. These results suggest that there are structural or functional changes, or both, in the muscle and skin circulation of patients with constitutional hypotension, whereas there are only structural or functional changes, or both, in the muscle circulation of patients with orthostatic hypotension.

Adult↗
PubMed1989

Vascular responses in forearm and calf to contralateral static exercises.

Ten normal subjects performed a 90-s isometric exercise [20, 30, and 40% of maximal voluntary contraction (MVC) of the flexor muscle of the right index finger or quadriceps muscle of the right leg. Contralateral forearm and calf blood flows (strain gauge plethysmography) and arterial blood pressure (auscultation) were measured simultaneously. Each exercise caused a decrease in forearm vascular resistance and a progressive increase in calf resistance. These changes were greatest with the 40% MVC. With finger exercise at 20 and 40% MVC, the percentage decreases in forearm vascular resistance from control were 12.3 and 22.7%, respectively (P less than 0.01). Similar decreases (9.5 and 24.9%, respectively; P less than 0.01) were noted with exercise of the quadriceps muscle. By contrast, the corresponding increases in calf vascular resistance were greater (P less than 0.01) with quadriceps exercise (13.3 and 55.4%, respectively) than with finger exercise (6.0 and 36.0%). Arrest of the circulation to the exercising muscles just before the exercise ended caused an abrupt increase in forearm vascular resistance and a decrease in calf resistance. These studies provide further evidence of the heterogeneity of responses of forearm and calf resistance vessels to certain cardiovascular stimuli.

Adult↗
PubMed1988

Reflex constriction of human limb resistance vessels to head-down neck flexion.

The effect of head-down neck flexion on forearm and calf blood flow was determined in 10 healthy male subjects. The subject lay prone, with the neck slightly extended and the chin resting on a soft-padded support at the edge of the table. The chin support was then removed, and the subject maximally flexed and lowered the neck. This was followed by return to the initial position. Neck flexion caused a rapid decrease in blood flow in both forearm and calf; at 30 s this averaged 39 and 35%, respectively. The flow in both forearm and calf gradually recovered as the neck flexion was sustained and approached the control values at the end of 10 min. The blood flow at the ankle was unchanged, indicating that the decrease occurred in the skeletal muscles. The arterial blood pressure and heart rate were unchanged; thus the decrease in flow was due to vasoconstriction. The fact that the decrease was evident as soon as the head was lowered indicated that it was nervously mediated. Neither contraction of the flexor muscles of the neck nor venous congestion of the head, in the absence of the head-down position, altered the blood flow. Although the mechanism of the decrease in flow has not been determined, the studies demonstrate that in response to certain stimuli, the resistance vessels in the skeletal muscles of the forearm and calf undergo a similar nervously mediated vasoconstriction.

Forearm↗
PubMed1987

Postural cardiovascular reflexes: comparison of responses of forearm and calf resistance vessels.

Simultaneous measurements were made of changes in vascular resistance in the forearm and calf in response to moving from supine to sitting or to head-down tilt. The subjects were healthy male volunteers, 21-63 yr. Blood flows were measured by venous occlusion plethysmography using mercury-in-Silastic strain-gauges. The gauges were maintained at the same level relative to the heart during the postural changes. Arterial blood pressure was measured by auscultation; heart rate was counted from the plethysmograms. Changing from supine to sitting caused a decrease in forearm blood flow from 4.13 +/- 0.14 to 2.16 +/- 0.19 ml.100 ml-1.min-1. Corresponding calf flows were 4.21 +/- 0.32 and 4.40 +/- 0.59 ml.100 ml-1.min-1. There was no change in mean arterial blood pressure, and heart rate increased by 8.0 +/- 1.5 beats/min. Arrest of the circulation of both legs with occlusion cuffs on the thighs before sitting, to prevent pooling of blood in them, reduced the degree of forearm vasoconstriction. Neck suction (40 Torr) during sitting, to oppose the decrease in transmural pressure at the carotid sinuses, inhibited the vasoconstriction. During a 30 degrees head-down tilt, there was a dilatation of forearm but not of calf resistance vessels. A Valsalva maneuver caused a similar constriction of both vascular beds. Thus, when changes in vascular resistance in forearm and calf are compared, the major reflex adjustments to changes in posture take place in the forearm.

Adult↗