scholarly journals Presyncopal cardiac contractility and autonomic activity in young healthy males

2009 ◽  
pp. 827-833
Author(s):  
E Grasser ◽  
N Goswami ◽  
H Hinghofer-Szalkay
Keyword(s):  
Blood Pressure ◽  
Lower Body Negative Pressure ◽  
Nervous Activity ◽  
Cardiac Contractility ◽  
Peripheral Resistance ◽  
Resistance Index ◽  
Left Ventricular ◽  
Orthostatic Stress ◽  
Frequency Variation ◽  
Healthy Humans

We investigated non-invasively cardiac contractility and autonomic nervous activity during presyncopal orthostatic stress induced in healthy humans. A graded orthostatic stress (GOS) paradigm, consisting of head-up tilt (HUT) combined with lower body negative pressure (LBNP) of increasing magnitude, was used to reach a presyncopal end-point in 15 healthy adults. Continuous beat-to-beat hemodynamic and autonomic parameters were recorded. From supine control (C1) to presyncope (PS), total peripheral resistance index (TPRI) decreased from 2300±500 to 1910±320 dyne*s*m²/cm^5 (p=0.004), index of contractility (IC) from 59±14 to 27±6 1000/s (p<0.0001), left ventricular working index (LVWI) from 5.2±1.3 vs. 3.6±0.6 mmHg*L/(min*m²) (p=0.0001) and acceleration index (ACI) from 65±18 vs. 54±15 100/s² (p=0.04). Low frequency variation of diastolic blood pressure (LFnudBP) increased from 51±14 to 67±11 % (p=0.0006) and of systolic blood pressure (LFnusBP) from 50±6 vs. 67±8 % (p<0.0001). High frequency variation of RR-interval (HFms²RRI) decreased from 385±320 to 38±43 ms² (p=0.001). From late GOS (G3) to PS, TPRI decreased from 2540±640 to 1910±320 dyne*s*m²/cm^5 (p=0.003), IC from 35±6 to 27±6 1000/s (p=0.003), LVWI from 4.6±0.9 to 3.6±0.6 mmHg*L/(min/m²) (p=0.003), LFnusBP from 71±8 to 67±8 % (p=0.03), LFmmHg²dBP from 6.6±4.0 to 4.8±2.9 mmHg² (p=0.0001), LFmmHg²sBP from 9.7±7.8 to 7.4±4.8 mmHg² (p=0.01). HFnuRRI increased from 19±8 to 28±13 % (p=0.008). Myocardial contractility indices and parameters of sympathetic activity were reduced in the presyncopal state, while parasympathic activity was increased. This suggests a decrease in cardiac contractility during orthostatically induced presyncope in healthy subjects.

Effects of gender and hypovolemia on sympathetic neural responses to orthostatic stress

2005 ◽  
Vol 289 (1) ◽  
pp. R109-R116 ◽  
Author(s):  
Qi Fu ◽  
Sarah Witkowski ◽  
Kazunobu Okazaki ◽  
Benjamin D. Levine
Keyword(s):  
Blood Pressure ◽  
Stroke Volume ◽  
Lower Body Negative Pressure ◽  
Muscle Sympathetic Nerve Activity ◽  
Peripheral Resistance ◽  
Orthostatic Stress ◽  
Stroke Index ◽  
Orthostatic Tolerance ◽  
Neural Responses ◽  
Men And Women

We tested the hypothesis that women have blunted sympathetic neural responses to orthostatic stress compared with men, which may be elicited under hypovolemic conditions. Muscle sympathetic nerve activity (MSNA) and hemodynamics were measured in eight healthy young women and seven men in supine position and during 6 min of 60° head-up tilt (HUT) under normovolemic and hypovolemic conditions (randomly), with ∼4-wk interval. Acute hypovolemia was produced by diuretic (furosemide) administration ∼2 h before testing. Orthostatic tolerance was determined by progressive lower body negative pressure to presyncope. We found that furosemide produced an ∼13% reduction in plasma volume, causing a similar increase in supine MSNA in men and women (mean ± SD of 5 ± 7 vs. 6 ± 5 bursts/min; P = 0.895). MSNA increased during HUT and was greater in the hypovolemic than in the normovolemic condition (32 ± 6 bursts/min in normovolemia vs. 44 ± 15 bursts/min in hypovolemia in men, P = 0.055; 35 ± 9 vs. 45 ± 8 bursts/min in women, P < 0.001); these responses were not different between the genders (gender effect: P = 0.832 and 0.814 in normovolemia and hypovolemia, respectively). Total peripheral resistance increased proportionately with increases in MSNA during HUT; these responses were similar between the genders. However, systolic blood pressure was lower, whereas diastolic blood pressure was similar in women compared with men during HUT, which was associated with a smaller stroke volume or stroke index. Orthostatic tolerance was lower in women, especially under hypovolemic conditions. These results indicate that men and women have comparable sympathetic neural responses during orthostatic stress under normovolemic and hypovolemic conditions. The lower orthostatic tolerance in women is predominantly because of a smaller stroke volume, presumably due to less cardiac filling during orthostasis, especially under hypovolemic conditions, which may overwhelm the vasomotor reserve available for vasoconstriction or precipitate neurally mediated sympathetic withdrawal and syncope.

Weight reduction in the management of hypertension: Epidemiologic and mechanistic evidence

1986 ◽  
Vol 64 (6) ◽  
pp. 818-824 ◽  
Author(s):  
Efrain Reisin
Keyword(s):  
Blood Pressure ◽  
Weight Loss ◽  
Weight Control ◽  
Sodium Intake ◽  
Close Association ◽  
Peripheral Resistance ◽  
Volume Ratio ◽  
Epidemiological Studies ◽  
Left Ventricular ◽  
Normal Weight

A number of studies have established a close association between increased body mass and elevated blood pressure. The presence of obesity in hypertensive subjects is associated with some hemodynamic, metabolic, and endocrinic characteristics: an increased intravascular volume with a high intracellular body water/interstitial fluid volume ratio, increased cardiac output, stroke volume, and left ventricular work while peripheral resistance was reduced or normal. Weight loss of at least 10 kg can reduce blood pressure independently of changes in sodium intake in obese persons of both sexes with mild, moderate, or severe high blood pressure. The fall in arterial pressure in obese hypertensives after weight loss may reverse many of the previously mentioned altered findings and underscore previous epidemiological studies that have shown that weight control could be an important measure in the treatment of hypertension.

Effects of Aging on the Variability of Arterial Pressure in Essential Hypertensive Patients

1982 ◽  
Vol 63 (s8) ◽  
pp. 411s-414s ◽  
Author(s):  
Jun Ogawa ◽  
Shigeo Takata ◽  
Gakuji Nomura ◽  
Shiro Arai ◽  
Takayuki Ikeda ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Stroke Volume ◽  
Systolic Blood Pressure ◽  
Diastolic Blood Pressure ◽  
Pulse Pressure ◽  
Baroreflex Sensitivity ◽  
Peripheral Resistance ◽  
Resistance Index ◽  
Average Systolic Blood Pressure ◽  
Effects Of Aging

1. We studied the effects of aging on the variability of blood pressure in mild to moderate essential hypertensive subjects. 2. Cardiac index was greater and total peripheral resistance index was less in patients under 40 years (by an average of 1.06 litres min−1 m−2 and 9.23 mmHg 1−1 min−1 m−2) than in those over 40 respectively (P < 0.001 for each). 3. Pulse pressure/stroke volume was less by an average of 0.345 mmHg/ml in patients under 40 years than that in those over 40 (P < 0.001). Pulse pressure/stroke volume was correlated with age (r = 0.621), average systolic blood pressure (r = 0.623) and inversely with baroreflex sensitivity (r = −0.494). 4. Baroreflex sensitivity was less by an average of 3.1 ms/mmHg in patients over 30 years than in those under 30 (P < 0.025). Baroreflex sensitivity was inversely correlated with age (r = −0.617) and average systolic blood pressure (r = −0.589). 5. Beat by beat variability of systolic blood pressure was correlated with age (r = 0.460), particularly when the data of those in their twenties were excluded (r = 0.618), and significantly with pulse pressure/stroke volume (r = 0.650), average systolic blood pressure (r = 0.618) and inversely with baroreflex sensitivity (r = −0.477). These relationships were not observed for diastolic blood pressure. 6. Maximum difference in systolic blood pressure in a day was correlated with pulse pressure/stroke volume (r = 0.482) and average systolic blood pressure (r = 0.648) but not with baroreflex sensitivity. These relationships were not observed for diastolic blood pressure. 7. Variability of systolic blood pressure in patients over 30 years gradually increased with age. In contrast, those of systolic and diastolic blood pressures in subjects in their twenties were relatively large. This might be related to factors other than aging, presumably those which underlie the hyperdynamic circulatory state.

Increased cardiac contractility in acute uremia: interrelationships with hypertension

1975 ◽  
Vol 229 (2) ◽  
pp. 501-505 ◽  
Author(s):  
T Nivatpumin ◽  
T Yipintsoi ◽  
S Penpargkul ◽  
J Scheuer
Keyword(s):  
Blood Pressure ◽  
Systolic Hypertension ◽  
Diastolic Pressure ◽  
Cardiac Contractility ◽  
Systolic Pressure ◽  
Pressure Rise ◽  
Left Ventricular ◽  
Ventricular Systolic Pressure ◽  
Inotropic State ◽  
Left Ventricular Systolic Pressure

To study the effects of acute uremia on the inotropic state of the rat heart, we subjected rats to bilateral nephrectomy and studied their hearts in the open chest 24 h later. Uremic rats had significantly higher systolic blood pressure than sham-operated animals. Left ventricular systolic pressure and maximum dP/dt, both during ejection and isovolumic contrations, were higher for any given end-diastolic pressure in hearts of uremic rats than in sham-operated animals. This difference in performance charcteristics was not abolished by doses of propranolol that blocked the heart rate response to isoproterenol. The administration of phenoxybenzamine during the 24 h of uremia abolished the blood pressure rise in uremic rats, but the increased contractile state persisted. Treatment of sham-operated animals with methoxamine to produce the same course of blood pressure as observed in uremic rats was also associated with an increased inotropic state. These results indicate that in the rat, acute uremia is associated with an increased inotropic state that is not mediated by beta-adrenergic mechanisms. The systolic hypertension of acute uremia is not the major cause of the increased contractility, although systolic hypertension without uremia can mimic the performance characteristics found in hearts of uremic rats.

Hemodynamic alterations in chronically conscious unrestrained diabetic rats

1987 ◽  
Vol 252 (5) ◽  
pp. H900-H905 ◽  
Author(s):  
L. F. Carbonell ◽  
M. G. Salom ◽  
J. Garcia-Estan ◽  
F. J. Salazar ◽  
M. Ubeda ◽  
...  
Keyword(s):  
Weight Control ◽  
Insulin Treatment ◽  
Cardiac Contractility ◽  
Peripheral Resistance ◽  
Left Ventricular Pressure ◽  
Diabetic Rats ◽  
Left Ventricular ◽  
Diabetic State ◽  
Hemodynamic State ◽  
Male Wistar Rats

Important cardiovascular dysfunctions have been described in streptozotocin (STZ)-diabetic rats. To determine the influence of these changes on the hemodynamic state and whether insulin treatment can avoid them, different hemodynamic parameters, obtained by the thermodilution method, were studied in STZ-induced (65 mg/kg) diabetic male Wistar rats, as well as in age-control, weight-control, and insulin-treated diabetic ones. All rats were examined in the conscious, unrestrained state 12 wk after induction of diabetes or acidified saline (pH 4.5) injection. At 12 wk of diabetic state most important findings were normotension, high blood volume, bradycardia, increase in stroke volume, cardiac output, and cardiosomatic ratio, and decrease in total peripheral resistance and cardiac contractility and relaxation (dP/dtmax and dP/dtmin of left ventricular pressure curves). The insulin-treated diabetic rats did not show any hemodynamic differences when compared with the control animals. These results suggest that important hemodynamic alterations are present in the chronic diabetic state, possibly conditioning congestive heart failure. These alterations can be prevented by insulin treatment.

Neuropeptide Y infusion improves hemodynamics and survival in rat endotoxic shock

1993 ◽  
Vol 265 (4) ◽  
pp. H1416-H1423 ◽  
Author(s):  
G. J. Hauser ◽  
A. K. Myers ◽  
E. K. Dayao ◽  
Z. Zukowska-Grojec
Keyword(s):  
Neuropeptide Y ◽  
Pressor Response ◽  
Endotoxic Shock ◽  
Lethal Dose ◽  
Peripheral Resistance ◽  
Resistance Index ◽  
Left Ventricular ◽  
Stroke Work ◽  
Adrenergic Agents ◽  
Key Factor

Neuropeptide Y (NPY), a sympathetic and platelet-derived vasoconstrictor, acts both directly and by potentiating adrenergic responsiveness and therefore may be beneficial in endotoxic shock, where suppressed vascular responsiveness to adrenergic agents is a key factor. This was studied in anesthetized rats. First, infusion of a nonhypotensive dose of endotoxin (lipopolysaccharide, LPS) markedly suppressed the pressor response to increasing doses of norepinephrine (NE), angiotensin II, and vasopressin but did not suppress the response to NPY. Second, in rats rendered hypotensive by intravenous LPS, continuous NE infusion (0.1-1.0 microgram.kg-1 x min-1 started 5 min after LPS for 1 h) did not alter hemodynamics. In contrast, 5 nmol.kg-1 x min-1 of NPY (equipotent to 0.1 microgram.kg-1 x min-1 of NE in normal rats) increased mean arterial pressure (MAP, from 64 to 114% of baseline), total peripheral resistance index (TPRI, from 64 to 154% of baseline), and left ventricular stroke work index (from 36 to 73% of baseline), without changing cardiac index (CI). Third, in a similar experimental protocol, pretreatment of the hypotensive rats with phentolamine blocked the pressor effect of NE infusion, but only partially attenuated the response to NPY. Finally, addition of low-dose NPY to NE infusion improved survival following a lethal dose of LPS compared with treatment with NE alone (P < 0.01). Thus, unlike other vasoconstrictors tested, NPY-mediated vasoconstriction is preserved during endotoxemia. The beneficial effect of NPY is mediated by increased TPRI without reduction in CI; both NPY receptor-mediated vasoconstriction and potentiation of adrenergic responsiveness may be involved.

Hemodynamic Strategies in Blood Pressure Regulation During Orthostatic Challenge in Women

1997 ◽  
Vol 22 (4) ◽  
pp. 351-367
Author(s):  
Tania L. Culham ◽  
Gabrielle K. Savard
Keyword(s):  
Blood Pressure ◽  
Arterial Pressure ◽  
Stroke Volume ◽  
Negative Pressure ◽  
Lower Body Negative Pressure ◽  
Peripheral Resistance ◽  
Orthostatic Tolerance ◽  
Lower Body ◽  
Orthostatic Challenge ◽  
Carotid Baroreflex

Several studies indicate that carotid baroreflex responsiveness is a good predictor of orthostatic tolerance. Two groups of healthy women with high (HI) and low (LO) carotid baroreflex responsiveness were studied (a) to determine any differences in the level of orthostatic tolerance of the two groups, and (b) to study the hemodynamic strategies used by HI and LO responders to regulate arterial pressure during the orthostatic challenge of lower body negative pressure (LBNP). Orthostatic tolerance was similar between the two groups, whereas the hemodynamic strategies recruited to maintain blood pressure at −40 mmHg LBNP differed: HI responders exhibited greater LBNP-induced decreases in stroke volume and cardiac output, as well as a greater increase in peripheral resistance compared to LO responders (p < .05). In addition, a significant increase in plasma renin activity during LBNP was found in the HI responders only. No significant between-group differences were found in arterial and cardiopulmonary control of vascular resistance or arterial haroreflex control of heart rate during LBNP. Key words: arterial pressure, carotid baroreceptor, lower body negative pressure, orthostatic tolerance, stroke volume

scholarly journals Heritability of Hemodynamic Reactivity to Laboratory Stressors in a Homogenous Arab Population: ‘Oman Family Study’

2009 ◽  
Vol 12 (6) ◽  
pp. 541-548 ◽  
Author(s):  
Mohammed O. Hassan ◽  
Riad A. Bayoumi ◽  
Juan C. Lopez-Alvarenga ◽  
Harold Snieder ◽  
Deepali Jaju ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Cardiovascular Reactivity ◽  
Acute Stress ◽  
Univariate Analysis ◽  
Peripheral Resistance ◽  
Left Ventricular ◽  
Left Ventricular Ejection ◽  
Arab Population ◽  
Heritability Estimates ◽  
Ventricular Ejection Time

AbstractBackground:Exaggerated cardiovascular reactivity to stressful stimuli may be a risk factor for the development of hypertension. The genetic influence on blood pressure (BP) reactivity to stress and its control mechanisms has been receiving considerable support. This study aims at examining the heritability of BP and its intermediate hemodynamic phenotypes to acute stress in a homogeneous Arab population.Methods:Parameters were computed from continuous BP, electrocardiography and impedance cardiography measurements, during rest, word conflict (WCT) and cold pressor (CPT) tests. Heritability estimates (h2) were obtained using the variance components-based approach implemented in the SOLAR software package.Results:Reactivity scores for WCT and CPT increased significantly (P< .05) for systolic (SBP), diastolic (DBP), heart rate (HR), cardiac output (CO), and total peripheral resistance (TPR). They decreased significantly (P< .05) for stroke volume (SV), left ventricular ejection time (LVET), end diastolic (EDI) and cardiac contractility (IC) indices. Univariate analysis detected heritability estimates that ranged from 0.19–0.35 for rest, 0.002–0.40 for WCT and 0.08–0.35 for CPT.Conclusion:In this unique cohort, resting as well as challenged cardiovascular phenotypes are significantly influenced by additive genetic effects. Heritability estimates for resting phenotypes are in a relatively narrow range, while h2for their reactivity is somewhat broader with lower estimates. Further analyses of this study may offer important opportunities for gene finding in hypertension.What is Known About the Topic:(1) cardiovascular reactivity to stress predicts cardiovascular disease; (2) genetic susceptibility plays an important role in stress reactivity. Family studies using the cold pressure test reported significant heritability for blood pressure.What this Study Adds:(1) this cohort is from five highly consanguineous isolated Arab pedigrees with genetically verified genealogical records and environmental homogeneity; (2) This is the first study to estimate heritability of detailed intermediate hemodynamic phenotypes that make up normal blood pressure.

Age-Specific Features of the Functional Development of the Circulatory System in Children Living in Northeastern Russia

2021 ◽  
pp. 34-38
Author(s):  
LI Grechkina ◽  
VO Karandasheva
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Peripheral Resistance ◽  
Left Ventricular ◽  
Human Interaction ◽  
Northeastern Russia ◽  
Special Importance ◽  
Functional Development ◽  
Age Related ◽  
Study Results

Summary. Introduction: The problem of human interaction with the environment acquires special importance nowadays. Significant migration processes observed in the last decade have become global, thus necessitating studies of the mechanisms of human adaptation to new environmental conditions. Our objective was to study age-related changes in functional indices of the cardiovascular system in adolescents between 11 and 17 years of age, born in Magadan in the first to third generation of Caucasians who had migrated to this city. Material and methods: In all, 1,442 school-age adolescents were examined including 809 boys and 633 girls. The main anthropometric parameters (body weight, kg, and height, cm) were measured and cardiac hemodynamics was determined at rest in the sitting position by volumetric compression oscillometry using a non-invasive hard- and software unit for central hemodynamic study. Results: Significantly higher values of cardiac output and stroke volume prevailed in boys of all age groups. The boys aged 14-17 years also demonstrated higher values of systolic blood pressure and left ventricular power output compared to girls. At the same time, the girls had higher age-specific indices of the heart rate, diastolic blood pressure, and total peripheral resistance. Conclusion: We established that the highest rates of cardiovascular functional development occur during puberty in 11 to 16-year-old boys and 11 to 13-year-old girls. Our findings showed that only 70.2 % to 77.2 % of the boys and 75.1 % to 80.2 % of the girls had blood pressure and heart rate readings within the age norm. Prehypertension was registered in 11.3 % and 10.3 % while hypertension was observed in 11.5 % and 9.5 % of the examined boys and girls, respectively. Tachycardia at rest was noted in 18 % of the boys and 20.2 % of the girls.

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