Biomedical subjects

D H Suarez

Publications and source records attributed to D H Suarez.

At least 19 recordsLinked to original sources

PubMed2000

Endothelium-dependent responses in patients with hypercholesterolemic coronary artery disease under the effects of simvastatin and enalapril, either separately or combined.

BACKGROUND: Endothelial dysfunction is an early event in atherosclerotic disease that precedes clinical manifestations and complications. The noninvasive assessment of endothelial function in patients with risk factors undergoing clinical treatment is an important medical advance. In this setting, altered endothelial function in patients with coronary hypercholesterolemia and its modifications by treatment with enalapril and simvastatin, either separately or in combination, was assessed in the brachial artery in a randomized, double-blind, 2-period crossover study. METHODS: Thirty-eight patients were separated in 2 groups. Group 1 (18 patients, 3 female, mean age 63 +/- 6.0 years) received simvastatin 10 mg/d for 8 weeks and simvastatin plus enalapril 5 mg/d for another 8 weeks. Group 2 (20 patients, 3 female, mean age 64 +/- 5.8 years) received enalapril 5 mg/d for 8 weeks and enalapril plus simvastatin 10 mg/d for another 8 weeks. All subjects underwent measurements of brachial artery diameter before and after postischemic hyperemia with high-resolution ultrasound at basal conditions (control) and under the effects of the drugs at the end of 8 and 16 weeks. RESULTS: Cholesterol and LDL cholesterol levels significantly decreased with simvastatin treatment alone or with enalapril. Mean baseline arterial diameter was 5.24 +/- 1.25 mm in group 1 and 4.83 +/- 0.99 mm in group 2 (not significant). In group 1 after the first 8 weeks, endothelium-dependent vasodilation significantly increased with simvastatin treatment (control, 4.4%; 8 weeks, 7.6%; P <.001). After 16 weeks with the addition of enalapril, a further increase in vasodilation was seen (8.6%, P <.05 vs 8 weeks). In group 2, with enalapril treatment an increase in vasodilation versus control was seen (control, 4.3%; 8 weeks, 5.8%; P <.01). After 16 weeks, with the addition of simvastatin an additional increase in vasodilation was observed (9.1%, P <.001 vs 8 weeks). After nitroglycerin, vasodilation in group 1 at control, 8, and 16 weeks was 17%, 17.5%, and 18%, respectively. In group 2, nitroglycerin vasodilation at control, 8, and 16 weeks was 21%, 21%, and 22%, respectively. CONCLUSIONS: Simvastatin significantly increased the postischemic vasodilator response in patients with coronary hypercholesterolemia, either as single treatment or added to enalapril. Similarly, the response was increased by enalapril, either alone or while simvastatin was being administered. Both drugs improve vasodilation and additive effects appear to be present.

Angiotensin-Converting Enzyme Inhibitors↗

PubMed1999

Impaired endothelial function in patients with rapidly stabilized unstable angina: assessment by noninvasive brachial artery ultrasonography.

BACKGROUND: Endothelial dysfunction may contribute to symptoms of instability in patients with acute coronary syndromes. High-resolution external ultrasound assessment of the brachial artery responses allows noninvasive determination of endothelial function. HYPOTHESIS: This study was conducted to assess endothelial function in patients with unstable angina using a noninvasive technique. METHODS: We studied 189 patients who were subdivided into three groups. Group 1: 60 apparently healthy subjects with no cardiovascular risk factors or symptoms of coronary artery disease; Group 2: 105 subjects with cardiovascular risk factors--arterial hypertension, hypercholesterolemia, cigarette smoking, diabetes, and obesity, but no evidence of coronary artery disease; and Group 3: 24 patients with unstable angina (chest pain at rest within the 24 h preceding study entry). All patients underwent pre- and postischemic brachial artery test evaluation with measurements of internal arterial diameters and blood flow. RESULTS: Results are expressed as percentage change from basal values. Subjects in Groups 1 and 2 showed a diameter increase of 19.1 and 11.9%, respectively, whereas patients in Group 3 showed a diameter change of 1.2% (p < 0.002 and < 0.0001, respectively). Calculated blood flow did not differ significantly in Groups 1 or 2 (74.4 and 56.4%), but was notably lower in Group 3 (18.4%, p < 0.005 vs. Groups 1 and 2). In nine patients of Group 3, the brachial studies were repeated 4 weeks after symptom stabilization and showed values comparable with those in Group 2. CONCLUSIONS: Patients with unstable angina showed endothelial dysfunction compared with control individuals. It is of interest that in patients whose symptoms were stabilized by medical therapy, endothelial function was restored 4 weeks after hospital discharge.

Adult↗

PubMed1984

Impaired systemic arterial compliance in borderline hypertension.

Arterial compliance was evaluated by pulse wave velocity, pulse pressure/stroke volume, and by an exponential analysis of the diastolic blood pressure decay curve in three groups of normotensive, borderline hypertensive, and established essential hypertensive patients. Two of the above three indices reflected significantly impaired arterial compliance in borderline hypertension, and all three indices were distinctly abnormal in patients with established hypertension. A close correlation among the three indices was observed in the entire study population. Multiple regression analysis indicated that age (p less than 0.005), systolic (p less than 0.005) and diastolic (p less than 0.025) pressure were independent determinants of pulse wave velocity; other factors such as total peripheral resistance, pulse pressure, and stroke volume were not. We conclude that arterial compliance becomes impaired early in hypertensive cardiovascular disease at the time when arterial pressure may be only slightly elevated. Thus structural alteration of the arterial wall can be demonstrated in borderline hypertension. Age, systolic and, to a lesser degree, diastolic pressures are the best determinants of arterial compliance in large vessels and are therefore important risk factors for evolving systemic arterial disease in essential hypertension.

Adult↗

PubMed1984

Arterial distensibility in young normotensive subjects and in patients with borderline and essential hypertension.

We evaluated the indices of arterial distensibility in a group (N = 40) of normotensive subjects and patients with borderline or established hypertension by measuring intra-arterial pressure, pulse wave velocity, and a mathematical modification of MOEN's formula to calculate arterial distensibility. Multiple linear regression analysis including six hemodynamic variables (systolic pressure [SP], diastolic pressure, mean arterial pressure, cardiac output, stroke volume, total peripheral resistance) and age showed that SP and age are the best predictor indices for arterial distensibility (P less than .025; both inversely correlated with arterial distensibility) and for pulse wave velocity (P less than .001; both positively correlated with pulse wave velocity). Patients aged 48 years and under (N = 35) with no evidence of target organ damage showed significant differences in arterial distensibility (F = 5.41; P less than .01) among normal, borderline, and established hypertensive subjects; arterial distensibility was lower in those with borderline (P less than .025) and established hypertension (P less than .01) when compared with the normal group. We concluded that arterial distensibility is decreased in borderline as well as in established essential hypertension without target organ involvement and that age and systolic pressure are the best predictors of arterial distensibility.

Adult↗

PubMed1982

Diurnal variations of cardiac rhythm, arterial pressure, and urinary catecholamines in borderline and established essential hypertension.

Ambulatory continuous ECG and arterial pressure (BP) were recorded simultaneously (Delmar Avionics Pressurometer II) for 24 hours in 13 age-matched normotensive subjects, 11 patients with borderline hypertension (HBP), and in 10 patients with uncomplicated established essential HBP. Urinary concentrations of epinephrine, norepinephrine, and dopamine were simultaneously collected over four successive 4-hour periods and one 8-hour period. Prevalence and total number of ventricular and supraventricular ectopic beats was low and not affected by arterial BP. Twenty-four-hour rate (HR) and 4-hourly excretion of epinephrine, norepinephrine, and dopamine were comparable between normotensive and HBP persons and no correlation between urinary catecholamines and arterial BP (systolic, diastolic, or mean), HR, or prevalence of ectopic beats was found in any of the three groups or in the total study population. We conclude that HBP patients without ECG evidence of left ventricular hypertrophy do not have a higher prevalence of supraventricular or ventricular ectopic beats. Urinary catecholamines are not related to circadian fluctuations or variability in arterial BP, HR, or prevalence of ectopic beats.

Blood Pressure↗

PubMed1982

Baroreceptor stimulation and isometric exercise in normotensive and borderline hypertensive subjects.

1. The effects of carotid baroreceptor stimulation (neck chamber) on systemic haemodynamics were determined for normotensive and borderline hypertensive subjects during periods of resting and isometric exercise. 2. Both groups reacted to baroreceptor stimulation with a similar decrease in mean arterial pressure and cardiac index at rest and during isometric exercise, but baseline heart rate decreased more in borderline hypertensive patients. 3. Baroreceptor stimulation elicited the same haemodynamic response at rest and during exercise-induced arterial pressure increase. Since the magnitude of arterial pressure had no bearing on the subsequent response, these data suggest resetting of baroreceptors during this short-term blood pressure increase.

Adult↗

PubMed1982

Hemodynamics, biochemical and reflexive changes produced by atenolol in hypertension.

Hemodynamic (systemic and regional), metabolic and cardiovascular reflexive variables were measured before and after 4 weeks of beta blockade with atenolol in 10 patients with mild essential hypertension. Atenolol reduced mean arterial pressure, heart rate, cardiac index (all p less than 0.005) and renal vascular resistance (p less than 0.01) and increased total peripheral resistance (p less than 0.005). Glomerular filtration rate and renal blood flow were unchanged; plasma renin activity fell 43%. Reflexive cardioacceleration during the Valsalva maneuver and upright passive tilt was blunted. No changes were observed in circulating fluid volumes. In six patients followed for 1 year, blood pressure and heart rate were maintained at levels similar to those during the first 4 weeks. Atenolol was shown to be an effective oral antihypertensive that has no apparent deleterious hemodynamic effects on the renal and splanchnic circulations.

Adrenergic beta-Antagonists↗

PubMed1982

Arterial compliance in systolic hypertension.

Arterial compliance as estimated by pulse wave velocity and the pulse pressure/stroke volume index was evaluated in 27 normotensive subjects, 21 patients with established, and 18 patients with systolic essential hypertension. Pulse wave velocity was elevated to the same degree in both hypertensive groups when compared to the normotensive controls. The pulse pressure/stroke volume index was higher in essential hypertension than in normotensive subjects and even higher in patients with systolic hypertension. It is concluded that both indices are useful clinical tools to determine arterial compliance. Systolic hypertension does not always indicate stiffening of the arterial tree, but may result from a high stroke volume in the presence of a normal arterial compliance.

Aorta, Thoracic↗

PubMed1981

Obesity and essential hypertension. Hemodynamics, intravascular volume, sodium excretion, and plasma renin activity.

Systemic hemodynamics, intravascular volume, and plasma renin activity were determined in 135 lean, midly obese, or distinctly overweight subjects who were normotensive or had borderline or established essential hypertension. Cardiac output (but not index) was higher and peripheral resistance lower in obese than in lean subjects, except in borderline hypertension. Intravascular volume was increased in obese patients, and more so when corrected for body height; correction for body weight led to relative volume contraction. Intravascular volume correlated directly with cardiac output in the entire population, as well as in the subgroups. Intravascular volume correlated inversely with total peripheral resistance in all subjects and in each subgroup. Both correlations remained significant when an approximation was used to correct influences of obesity on total blood volume. Sodium excretion was higher in obese than in lean subjects. Thus, despite the expanded intravascular volume in obesity, the pathophysiologic relationship between systemic hemodynamics and intravascular volumes remains unchanged. Relatively low peripheral resistance in obesity may decrease the risk of systemic vascular disease. Nevertheless, since circulating volume is increased, the greater venous return adds an additional load to a left ventricle that is already burdened by a high afterload caused by arterial hypertension.

Adult↗

PubMed1981

Echocardiographic diastolic ventricular abnormality in hypertensive heart disease: atrial emptying index.

To analyze changes in left ventricular diastolic properties in hypertensive heart disease, the atrial emptying index was used to assess the rapid phase of diastolic filling of the left ventricle. Ten normal subjects (Group 1), 11 hypertensive patients without evidence of cardiac involvement (Group 2) and 10 hypertensive patients with echocardiographic evidence of left ventricular hypertrophy (Group 3) were compared using M mode echocardiography and systemic hemodynamic data. Whereas cardiac index (dye-dilution method) and rate of circumferential fiber shortening (echocardiogram) were normal in all three groups, there was a progressive increase in left atrial index (p less than 0.001, Group 1 versus Group 2 and versus Group 3) and a progressive decrease in the atrial emptying index (p less than 0.001, Group 1 versus Group 2 and versus Group 3). No correlation existed between the atrial emptying index and the left atrial index, mean arterial pressure or total peripheral resistance in any of the three groups. These data suggest that rapid filling of the left ventricle is reduced early in hypertension, even before electrocardiographic or systolic echocardiographic abnormalities are detectable. The atrial emptying index therefore appears to be an early indicator of abnormalities of left ventricular diastolic compliance in uncomplicated hypertension.

Adult↗

PubMed1981

Borderline hypertension: relationship between age, hemodynamics and circulating catecholamines.

The relationships between age, systemic and renal hemodynamics, circulating catecholamines (norepinephrine, epinephrine and dopamine) and intravascular volumes were studied in 38 normotensive subjects and in 77 patients with borderline essential hypertension. Borderline hypertensive patients had a higher cardiac index (p less than 0.02) and renal blood flow (p less than 0.05) than normotensive subjects if they were younger than 30 years of age, whereas in older patients no difference was observed. In contrast, total peripheral resistance was normal in young borderline hypertensive patients, but significantly increased (p less than 0.02) in patients older than age 40 years. Cardiac output (r = -0.28, p less than 0.01) and renal blood flow (r = -0.47, p less than 0.001) correlated inversely with age in the entire population and in both subgroups. Cardiac output also correlated closely with renal blood flow in all subjects (r = 0.45, p less than 0.001). Circulating norepinephrine levels increased with age (r = 0.25, p less than 0.05), whereas epinephrine concentration tended to decrease. Plasma and total blood volume correlated directly with cardiac output (r = 0.39, p less than 0.001) and inversely with peripheral resistance (r = -0.34, p less than 0.001). These data indicate that the hyperdynamic circulation (high cardiac output and renal blood flow) of borderline hypertension is found predominantly in patients younger than age 30 years. Older patients are characterized by an elevated total peripheral resistance and normal cardiac output. The age-dependent increase in circulating norepinephrine and decrease in epinephrine levels may participate in the shift of the hemodynamic profile from high-cardiac-output hypertension in the young to a high-arteriolar-resistance hypertension in the older patient.

Adolescent↗

PubMed1981

Patterns of left ventricular adaptation in borderline and mild essential hypertension. Echocardiographic findings.

To assess patterns of left ventricular adaptation, 38 patients with borderline and 38 with sustained mild essential hypertension, all lacking electrocardiographic and roentgenographic criteria for left ventricular hypertrophy, were compared using systemic hemodynamic values and M-mode echocardiograms. All patients had normal left ventricular function and measurements of wall thickness. Those with borderline hypertension showed no asymmetric increase in the ratio of septal to posterior wall thickness. The ratio of the left ventricular radius to wall thickness remained normal in both groups, indicating no disproportionate hypertrophy or dilatation of chambers during the phase of normal left ventricular function. Neither finding substantiates asymmetric septal hypertrophy in early hypertension. Those with mild essential hypertension demonstrated an augmented mean circumferential fiber shortening rate compared to those with borderline hypertension (P less than 0.005), suggesting an early stage of left ventricular hyperfunction in the development and elaboration of hypertensive heart disease.

Adult↗

PubMed1980

Systemic and regional haemodynamics in anterior hypothalamic hypertension in spontaneously hypertensive and Wistar-Kyoto rats.

1. Systemic and regional haemodynamics were determined in conscious Wistar-Kyoto and spontaneously hypertensive rats with the radioactive microsphere technique after sham lesion or bilateral electrolytic lesion of the nuclei of the anterior hypothalamus. 2. Anterior hypothalamic lesions produced an increase in blood pressure, heart rate and cardiac output. 3. In the rats with lesions there were changes in regional haemodynamics: heart and skeletal muscle flow increased; renal, skin ans splanchnic flow decreased. 4. The haemodynamic consequences of ablation of the anterior hypothalamus were similar in both normotensive Wistar-Kyoto and spontaneously hypertensive rats. The haemodynamic pattern resembles that seen during fighting and exercise.

Animals↗

PubMed1980

Haemodynamic changes associated with obesity and high blood pressure in rats with ventromedial hypothalamic lesions.

1. The haemodynamic and plasma volume changes associated with obesity and high blood pressure were studied in nine male rats with electrolytic ventromedial hypothalamic lesions and their paired sham-operated controls. Body weight and arterial pressure were greater in the rats with ventromedial hypothalamic lesions (565 +/- 16 vs 462 +/- 14 g, P < 0.001; 128 +/- 3 vs 118 +/- 3 mmHg, P < 0.05, respectively). Cardiac output was slightly elevated, and that portion of cardiac output distributed to the kidneys was reduced (P < 0.001). Plasma volume was contracted in the rats with ventromedial hypothalamic lesions (21.0 +/- 0.1 vs 2.8 +/- 0.1 ml/100 g, P < 0.001). 2. The haemodynamic characteristics of rats in which obesity and mild hypertension have been induced by electrolytic ventromedial hypothalamic lesion are similar to mild obesity essential hypertension in men.

Animals↗

PubMed1980

Asymptomatic mild hyperuricaemia: an indicator of nephrosclerosis in essential hypertension.

1. Glomerular filtration rate, renal and systemic haemodynamics and intravascular volume were measured in 20 established essential hypertensive patients classified according to serum uric acid level into two groups (below 0.36 mmol/l, and above 0.54 mmol/l). 2. Although glomerular filtration rate was comparable between the two groups, renal blood flow was lower and renal vascular and total peripheral resistances were higher in the patients with the highest uric acid levels (P < 0.02). 3. Cardiac output, heart rate and splanchnic blood flow were similar in both patient groups but arterial pressure tended to be higher in patients with high uric acid levels. 4. These data suggest that unexplained hyperuricaemia in patients with essential hypertension most likely reflects early renal vascular involvement, i.e. nephrosclerosis.

Adult↗

PubMed1980

Serum uric acid in essential hypertension: an indicator of renal vascular involvement.

We measured glomerular filtration rate, renal and systemic hemodynamics, and intravascular volume in normotensive subjects and in borderline and established essential hypertensive patients classified according to serum uric acid level. Renal blood flow was lower and renal vascular and total peripheral resistances were increased in patients with high uric acid levels (p < 0.02). Serum uric acid concentration correlated inversely with renal blood flow/m2 body surface area (r = -0.45, p < 0.001) and directly with renal vascular (r = 0.41, p < 0.001) and total (r = 0.38, p < 0.001) resistance. Cardiac output, heart rate, and intravascular volume as well as glomerular filtration rate showed no uric-acid-department pattern. Mild asymptomatic hyperuricemia, therefore, was associated with decreased renal blood flow without affecting glomerular filtration rate. Increased renal vascular and total peripheral resistances reflecting renal and systemic hypertensive vascular disease paralleled the rising serum uric acid levels. These data suggest that heretofore unexplained hyperuricemia in patients with essential hypertension most likely reflects early renal vascular involvement, specially, nephrosclerosis.

Adult↗

PubMed1979

Effects of beta blockade with acebutolol on hypertension, hemodynamics, and fluid volume.

Eleven patients with essential hypertension were treated with the beta adrenergic blocker, acebutolol. Clinical, systemic, and regional hemodynamic and biochemical studies were performed before and after 4 wk of acebutolol therapy (average doses, 1,200 mg/day.) In 4 patients there was a reduction in mean arterial pressure greater than or equal to 10 mm Hg; there was none in the remainder. Regardless of the blood pressure response, the renin secretory index did not change. Although cardiac output did not change, renal blood flow fell (p less than 0.005) without relation to response of arterial pressure. Supine heart rate decreased (p less than 0.05), so also the responses to upright tilt (p less than 0.01) and isometric exercise (p less than 0.02). These results demonstrate that in those patients with a hypotensive response to acebutolol, the clinical effect was not related to reduced cardiac output or plasma renin activity, further adding to confusion on the mechanism of the lowering of elevated blood pressure by beta adrenergic blockade.

Acebutolol↗

PubMedDate not supplied

Systemic and regional hemodynamic changes associated with anterior hypothalamic lesions in conscious rats.

Systemic and regional hemodynamics were determined with the radioactive microsphere technique either in conscious "sham-lesioned" Wistar rats or after bilateral electrolytic lesions of the nuclei of the anterior hypothalamus. Both mean arterial pressure (111 +/- 4 vs 152 +/- 3 mm Hg) and heart rate (376 +/- 15 vs 504 +/- 12 beats/min) were significantly increased 2 hours after lesioning (p less than 0.001). Although cardiac output tended to increase, it did not attain statistical significance; therefore this form of neurogenic hypertension is characterized by increased total peripheral resistance. Regional hemodynamics were measured 2 hours after placement of the lesions: skeletal muscle flow increased, renal cutaneous and splanchnic flows decreased, and brain and myocardial flows were preserved. These hemodynamic alterations were associated with significant elevations in plasma norepinephrine and epinephrine levels, and behavioral changes characterized by hypermotility, aggressitivity, and irritability, which resembled those seen during fighting and exercise.

Animals↗