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PubMed1991

A comparison of the hemodynamic effects of endothelin-1 and sarafotoxin S6b in conscious rats.

The hemodynamic effects of sarafotoxin S6b (SRT) and endothelin-1 (ET-1) were studied in conscious, freely moving rats. Intravenous bolus administration of ET-1 produced an initial transient depressor response and skeletal muscle (hindquarters) vasodilation. This depressor activity was not observed after i.v. SRT except at a high dose. The initial fall in blood pressure was followed by a sustained pressor response and an increase in total peripheral resistance which were mediated, at least partially, by visceral (mesenteric) and skeletal muscle (hindquarters) vasoconstriction. The durations of the pressor responses and times required to achieve the peak pressor effects (peak time) were greater for ET-1 as compared to SRT. The results of qualitatively similar sustained hemodynamic effects and the strong correlation between the amplitude of the responses to ET-1 and SRT in individual rats suggest that the sustained pressor responses to these peptides are mediated by the same receptors, although the potency was significantly greater for ET-1 than for SRT. Furthermore, the initial depressor and sustained pressor responses appear to be mediated by distinct receptor subtypes inasmuch as the same dose of ET-1 was required for both vasodilator and vasoconstrictor activity but a higher dose of SRT was required to elicit its vasodilator as compared to constrictor effects. Thus, SRT may have relatively lower affinity for receptors mediating its initial hemodynamic responses whereas ET-1 binds with equal affinity to both receptors. These potent and vascular specific hemodynamic actions suggest a role of endothelin in regulating cardiovascular function.

Animals↗
PubMed1991

Hemodynamic effects of pressure support ventilation in cardiac surgery patients.

Hemodynamic consequences of pressure support ventilation (PSV) were compared with intermittent mandatory ventilation (IMV) in 20 patients following aortocoronary bypass. On the morning following surgery, all patients were weaned by IMV to a rate of eight breaths per minute, tidal volume of 12 ml/kg and inspired oxygen concentration of 40 per cent. With patients awake and able to breath spontaneously, PSV was begun at 20 cm of water. In patients with static lung compliance, less than 0.06 l/cm H2O, 30 cm H2O of PSV was used. Subsequently, all patients were weaned to PSV 10 cm of water, continuous positive airway pressure (CPAP) at 5 cm water and extubated. Hemodynamic data including oxygen transport were obtained at each level of PSV and at IMV prior to weaning. Analysis using ANOVA showed comparable hemodynamic and oxygen transport parameters for PSV of 30 cm H2O in comparison with IMV. PSV at levels of 20 and 10 cm H2O produced statistically significant increases in heart rate, mean arterial pressure, central venous pressure, and pulmonary capillary wedge pressure. Cardiac output was stable, and these increases were not clinically significant. In awake patients following cardiac surgery, PSV up to 30 cm H2O can be safely applied without hemodynamic embarrassment in patients with good left ventricular ejection fractions.

Blood Gas Analysis↗
PubMed1990

[Role of intrathoracic pressure in changes in the greater and lesser circulation hemodynamics in patients with bronchial asthma].

The greater and lesser circulation hemodynamics was examined in 59 patients with bronchial asthma and 23 controls by tetrapolar rheography, kinetocardiography, and ultrasonic Doppler cardiography. Simultaneously measurements of intrathoracic pressure (ITP) were carried out with an esophageal controller. Reduced stroke index, increased total peripheral resistance of the vessels, and elevated systolic pressure in the pulmonary artery were revealed in the patients as against the controls. ITP values in asthmatics surpassed twofold those in the reference group. To reveal elevated ITP effects on the hemodynamics, the authors have examined the hemodynamic parameters during Valsalva's test (with elevation of oral pressure up to 25-35 mm Hg) in 16 reference subjects. The results evidence the leading role of elevated ITP on the greater and lesser circulation hemodynamics in asthma. Elevated ITP lowers the venous blood flow to the heart and reduces the preload thus decreasing the blood flow to the lesser circulation and not increasing the pulmonary artery systolic pressure.

Adult↗
PubMed1990

[Effect of nitroglycerin preparations on indicators of central hemodynamics in patients with pulmonary tuberculosis complicated by chronic cor pulmonale].

The effect of nitroglycerin drugs on central hemodynamic indices in 198 patients with pulmonary tuberculosis and chronic nonspecific pulmonary diseases was investigated. These studies revealed that in pulmonary tuberculosis, nitroglycerin caused blood pooling in peripheral vessels, a decrease in the central hemodynamic indices and an increase in the right heart. A single dose of nitrogen, 2.6 mg, given to a patient with hypokinetic circulation leads to the improvement of the central hemodynamic indices (circulating blood volume (CBV), stroke and cardiac indices, lung CBV) due to less peripheral angiospasm, peripheral circulation normalization and better blood supply to the right heart. A fortnight nitrogen regimen in a dosage of 2.6 mg thrice a day makes it possible to normalize the central hemodynamic indices and decrease pressure in the pulmonary artery in patients with pulmonary tuberculosis complicated by a chronic pulmonary heart with a hypokinetic circulation.

Adult↗
PubMed1990

Changes of blood humoral substances in experimental cirrhosis and their effects on portal hemodynamics.

The changes of humoral substances in the blood of cirrhotic rats were studied together with their effects on portal hemodynamics at different stages during the development of cirrhosis. The profiles of humoral substances and hemodynamics in two different cirrhotic rat models were also investigated. During the development of cirrhosis, glucagon increased markedly in all stages, histamine and vasoactive intestinal polypeptide (VIP) increased in the early stage, serotonin (5-HT) and somatostatin (SS) increased in the middle and late stages. There were different patterns of humoral substances in different cirrhotic models. Glucagon was the main humoral substance elevated in CCL4 induced cirrhosis, but histamine and 5-HT were mainly elevated in the blood in thioacetamide (TAA) induced cirrhosis. The hemodynamics altered differently in different stages during the development of cirrhosis and differently in the two cirrhotic rat models. Exchange transfusions between normal and cirrhotic rats resulted in an elevation of portal flow in normal rats, but no such changes were found after exchange pressure and an increase of portal blood transfusions between normal rats. The relationship between the humoral substances and portal hemodynamics is discussed. The results of this study strongly support the hypothesis of "humoral mechanism" in the pathogenesis of portal hypertension due to cirrhosis.

Animals↗
PubMed1990

Role of glucagon in the splanchnic and systemic hemodynamic changes induced by portal-systemic blood shunting.

Portal-systemic blood shunting is often accompanied by hyperglucagonemia and hemodynamic changes. To determine this causal relation, splanchnic and systemic hemodynamics (radioactive microspheres) and plasma glucagon levels (radioimmunoassay) were assessed in conditions of total portal-systemic shunting in portacaval-shunted (PCS) rats and in sham-operated (SO) normal rats. To compare these results, another hemodynamic study was undertaken basally and during glucagon infusion in nonoperated normal rats. PCS rats showed a threefold greater plasma glucagon concentration than SO animals (924 +/- 134 vs. 309 +/- 18 pg/ml, p less than 0.01), and they developed a hyperdynamic splanchnic circulation with higher portal venous inflow than SO rats (8.29 +/- 1.1 vs. 5.09 +/- 0.4 ml/min/100 g, p less than 0.05). Infusion of a pharmacological dose of glucagon in normal rats increased portal venous inflow (from 4.92 +/- 0.33 to 6.24 +/- 0.48 ml/min/100 g, p less than 0.05) so as to imply this hormone in the development of the hyperdynamic splanchnic circulation in conditions of portal-systemic shunting. However, the discrepancies in systemic hemodynamics between PCS and glucagon-infused rats may be a result of the different plasma glucagon levels reached in the two groups.

Animals↗
PubMedDate not supplied

Hemodynamic influence of LVAD on right ventricular failure.

Left ventricular assist device (LVAD) pumping has hemodynamic and anatomic influences on right ventricular performance. A total artificial heart (TAH) model was employed to better understand the hemodynamic influence of an LVAD on the failing right ventricle. Biventricular failure was simulated by reducing both ventricular drive pressures of the TAH. After getting hemodynamic data, LVAD pumping in the case of right ventricular failure was simulated by increasing just the left ventricular drive pressure. In the LVAD-simulating condition, cardiac output increased and right atrial pressure decreased significantly (p less than 0.05) compared with the biventricular failure condition, whereas right ventricular function and minute work were the same in these two conditions. Even though changes were accompanied by adaptive increases in pulmonary resistance, substantially lower pulmonary artery and left atrial pressures resulted in the LVAD-simulating condition. From a hemodynamic perspective, these results indicate that an LVAD can increase right ventricular volume work by decreasing right ventricular pressure work, whereas right ventricular net pressure-volume work is unchanged and right ventricular failure is not worsened.

Animals↗
PubMed1990

[Analysis of the indicators of central and peripheral hemodynamics in families with arterial hypertension].

Arterial pressure was studied by ++tacho-oscillography, and the central and peripheral hemodynamics were examined by tetrapolar rheography in members of 62 families with essential arterial hypertension. A geneticodispersion analysis was made of phenotypic dispersion of the parameters under study. The genetic determinant with an X-chromosome effect was established for minimal and lateral systolic pressure; that with a maternal effect for mean pressure. A high degree of the inheritance of the varieties of the central hemodynamics was discovered. Analysis of the peripheral hemodynamics points to an important role played by venoconstriction in the establishment of arterial hypertension. A high level of genetic determination with an X-chromosome effect was found for the readings of the leg rheogram (beta, alpha + alpha, alpha + beta/RR), responsible for the blood content and venous outflow. The data obtained provide evidence in favour of the prospective + search for genetic markers among the parameters of arterial pressure, the central and peripheral hemodynamics.

Adolescent↗
PubMedDate not supplied

[Retrospective analysis of the parameters of ocular hemodynamics in patients with initial open-angle glaucoma].

The authors analyze ocular hemodynamics parameters in patients with ocular hypertension who were transferred to glaucoma group during ten-year follow-up. The patients who were transferred to this group were those whose hemodynamic parameters were lower than in the reference group. By the end of the follow-up period a negligible reduction of the hemodynamic parameters was observed in the 'hypertension' group and a statistically significant reduction in glaucoma patients. This lead the authors to a conclusion on the necessity of early prescription of drugs stimulating disordered ocular hemodynamics.

Aged↗
PubMed1990

Hemodynamic changes after an intensive short-term exercise and nutrition program in hypertensive and obese patients with and without coronary artery disease.

PURPOSE: To assess the effectiveness of the Pritikin diet and exercise program on cardiovascular hemodynamics using the noninvasive technique of Thoracic Electrical Bioimpedance (TEB). MATERIAL AND METHODS: Twenty subjects divided in two groups, according to their body habitus and hemodynamic disturbances. These data were compared to a group of 10 healthy individuals not involved in the program. Hemodynamic parameters were collected at admission and at the end of the intensive 26-day program of exercise and nutrition. RESULTS: In obese and hypertensive subjects not on medication we observed that cardiac index increased from 3.27 +/- 0.4 to 3.58 + 0.5 L/min/m2; mean arterial pressure decreased from 100 +/- 8.5 to 94.8 +/- 7.9 mmHg while systemic vascular resistance index decreased from 2362 +/- 391 to 1934 +/- 357 dynes. sec. cm-5/m2; p less than 0.05 (Data obtained in supine position). Also documented was a improvement in ventricular performance after postural changes from upright to supine based on indices of left ventricular performance, uniquely obtained by the TEB technique. From admission to discharge, changes were: Ejection fraction 48% to 53%; Peak flow index 295 to 316 ml/s/m2 and Index of contractility 40 to 47 s-1, explained by a shift on the ascending limb of the Starling curve. CONCLUSION: In a selected population, this rehabilitation program is effective for hemodynamic improvement that can be partially explained by metabolic and biochemical changes already reported from this Center.

Adult↗
PubMed1990

[Changes in central hemodynamics in persons with borderline arterial hypertension during work-related activities].

Changes in the function of the cardiovascular system were studied in 30-39- and 40-49-year-old healthy subjects and patients with borderline arterial hypertension (BAH) who worked 8 or 12 hours every day. During an 8-hour working day, altered central hemodynamics was shown to be detected both in healthy subjects and BAH patients only at the age of 30-39 years and reflected by higher stroke volume (SV), higher cardiac output (CO) and lower total peripheral resistance (TPR) in healthy subjects and diminished heart rate (HR), CO in BAH patients. With this, the distribution of hemocirculatory patterns remained the same as it had been before work. After 12-hour work, the central hemodynamic changes were unindirectional in all the groups in question: decreased HR, SV, CO, cardiac index and increased TPR. There was a decrease in hyperkinetic hemodynamic incidence and an increase in eu- and hypokinetic hemodynamic one.

Adult↗
PubMedDate not supplied

Low-dose oral prednisone in the treatment of acute cardiac allograft rejection not associated with hemodynamic compromise.

The standard therapy for acute cardiac allograft rejection is intravenous methylprednisolone, usually in doses of about 3 gm per treatment. Treatment is undertaken in most cases solely on the basis of a histologic diagnosis of rejection, irrespective of hemodynamic status. To reduce total corticosteroid dose and administer therapy in an outpatient environment, low-dose oral prednisone protocols were developed for the treatment of acute rejection in the absence of important hemodynamic compromise. A high-dose oral prednisone pulse (2 gm total for the average 75 kg male patient) was used in the first month. Thereafter a series of low-dose oral prednisone pulses were used (range, 0.5 to 1.0 gm total for the average 75 kg male patient). Of 85 transplant recipients at risk, 188 rejection episodes were treated over a 1477 total patient-months of follow-up. The high-dose oral pulse resulted in successful therapy (no subsequent therapy required) in 34 of 65 treatments (52%). The low-dose oral pulse was successful in treating 80 of 123 treatments (65%). This approach to acute rejection did not appear to adversely affect patient or graft outcome based on progression of stable to unstable hemodynamics, survival (84% and 82%, 1- and 2-year actuarial survival, respectively), or left ventricular ejection fraction (0.56 +/- 0.09 and 0.54 +/- 0.08, at 1 and 2 years, respectively). There did not appear to be discriminating factors that determined the therapeutic outcome, other than the higher failure rate within 1 month of transplant. We conclude that acute allograft rejection in the absence of important hemodynamic compromise responds to lower-than-conventional doses of corticosteroids in the majority of cases.

Administration, Oral↗
PubMedDate not supplied

[Hemodynamics and rheologic properties of the blood in meningococcemia associated with meningitis and complicated by septic shock and intracranial hypertension].

Central hemodynamic parameters characterizing cardiac contractility and peripheral resistive vascular tone, as well as blood aggregation ability, its structural and dynamic viscosity have been assessed by dynamic (disease duration up to 15 days) and complex studies in 28 patients with septic shock of meningococcal etiology accompanied by signs of meningitis. All the patients revealed signs of intracranial hypertension caused by the onset of acute hydrocephaly or brain edema. It has been demonstrated that on entry all the patients were characterized by the combination of low cardiac output syndrome and second degree high or low blood viscosity. In addition to endotoxemia, acute intracranial hypertension that enhances the afterload and blood viscosity abnormalities are involved in the development of hemodynamic disturbances. Over the whole observation period elevated intracranial pressure had a certain effect on central hemodynamics, changing according to the mechanism similar to that observed in Cushing's syndrome. In addition, central hemodynamics and blood viscosity are directly or indirectly (via affected CNS) influenced by Herpes infection developing on days 2 to 5 of the disease.

Adolescent↗
PubMed1986

[Pulsed Doppler echocardiographic evaluation of hemodynamics in premature ventricular contractions].

To investigate hemodynamic changes in ventricular premature contractions (VPCs), the blood flow velocities at the left ventricular (LV) outflow and inflow tracts were analyzed by pulsed Doppler echocardiography in 23 patients with VPCs and in two patients with ventricular parasystoles. Percent LV stroke volume of the ectopic and the postectopic sinus beats to the other sinus beats and %LV inflow volume of the sinus beats preceding ectopic beats to the other sinus beats were calculated from the time integral of the blood flow velocity. The following results were obtained. The %LV stroke volume of VPCs or %LV inflow volume of the preceding sinus beats correlated positively with the coupling interval of VPCs (r = 0.69, p less than 0.001 and r = 0.67, p less than 0.001, respectively). The %LV stroke volume of VPCs correlated positively with %LV inflow volume of the preceding sinus beats (r = 0.84, p less than 0.001). In some patients with VPCs of the RBBB pattern and in one patient with VPCs of the LBBB pattern associated with abnormal right axis deviation, the %LV stroke volume of VPC was much more reduced. In patients with depressed rapid filling and increased atrial filling, %LV stroke volume of the VPC or %LV inflow volume of the preceding sinus beat was smaller than in the other patients with the same coupling interval of VPCs. In VPCs of right ventricular (RV) origin, deterioration of RV hemodynamics was more prominent than in those of LV origin, and vice versa. Increased LV stroke volume was observed in postextrasystolic sinus beats, related to the coupling intervals of VPCs. However, the sum of %LV stroke volume of VPC and the postextrasystolic sinus beat decreased as the coupling intervals of VPC shortened. These results suggest that not only the coupling interval and the origin of VPCs but the LV diastolic behavior, as well, are important factors determining the hemodynamics in VPCs. They also suggest that the increment of stroke volume in postextrasystolic beats is more prominent in VPCs with shorter coupling intervals, but the LV performance as a whole is more depressed in VPCs with a shorter coupling intervals. In conclusion, pulsed Doppler echocardiography proved a useful noninvasive technique for evaluating the hemodynamics of VPCs.

Cardiac Complexes, Premature↗
PubMed1987

Hemodynamics in hypertension at rest and during exercise.

The results of the last 20 years have shown that the hemodynamic mechanisms behind the increased blood pressure in essential hypertension differ widely and depend at least on the age of the patients and the stage of the hypertensive disorder. The cardinal hemodynamic disturbance is increased vascular resistance seen in most vascular beds, but to a different extent in various other areas. Even in relatively young subjects (20-40 years) with mild hypertension, where the typical hemodynamic pattern is an increased cardiac index during rest with almost "normal" total peripheral resistance, exercise studies show that total peripheral resistance does not fall as in normotensive age-matched controls. The heart pump function is slightly reduced (subnormal stroke index and cardiac index during exercise). When hypertension is left untreated, the hemodynamic pattern changes over time, toward the "low cardiac output--high resistance" pattern--associated with reduced left ventricular compliance--and left ventricular hypertrophy in a large fraction of the patients. Blood flow to such vital organs as the brain, the kidneys, and the myocardium diminishes. The initiating and maintaining mechanisms responsible for the high blood pressure include disturbances in the central nervous system, in the catecholamines, in the various vasoactive peptides, reduced compliance of the venous system, and probably an inborn tendency to structural changes and increased stiffness in the heart as well as in the major vessels. These are the changes we would like to prevent or reverse with our antihypertensive treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗
PubMed1988

The hemodynamics of the aging cardiovascular system.

Our information on the hemodynamics of the aging cardiovascular system in normotensive and hypertensive subjects is mainly based on cross-sectional studies. In normotensive subjects with no indication of coronary heart disease, recent noninvasive studies seem to indicate that cardiac output at rest and during exercise does not decline with age. These results contrast with what has been found by invasive studies in unselected populations. In hypertensive subjects it is well established that the hemodynamics of young subjects at the early stage differ greatly from what is seen in elderly hypertensive subjects. In the early phase, a high resting cardiac output is typical, whereas in the elderly, cardiac output is very low and total peripheral resistance (TPR) very high. Echo studies have shown that left ventricular hypertrophy develops early in hypertension--together with increased stiffness and reduced left ventricular compliance. A subnormal stroke volume during exercise is seen early in the process of hypertension. Data from the 20-year follow-up study of the Bergen population demonstrate that in groups of young (17-29 years) versus elderly (60-69 years) patients with hypertension with the same mean arterial blood pressure, the hemodynamic mechanisms behind increased blood pressure were widely different. The increase in mean arterial blood pressure during exercise was much steeper in the older subjects than in the younger ones, and TPR was about twice as high during 150 W exercise. Cardiac index (CI) in the oldest group was approximately half of that in the youngest group. The differing hemodynamic patterns in the young and elderly might have implications for when and how to start drug treatment, and also for what type of treatment to select.

Adult↗
PubMed1989

[Correction of disorders of systemic hemodynamics and rheologic indices of the blood in patients with chronic kidney failure during hemodialysis].

During hemodialysis, 44 patients with terminal chronic renal failure were examined for the systemic hemodynamics and blood rheological properties as well as for the possibility of their correction by infusion of the plasma substitutes: polyglucine, rondex or 10% albumin at a volume of 400 ml per administration. It was established that patients on hemodialysis manifested pronounced hemodynamic and rheological disorders. During hemodialysis, the hemodynamic disorders correlated with the changes in the rheological properties of the blood (r = 0.23-0.45, p less than 0.05). It is indicated that to treat the hypotensive states occurring in the course of hemodialysis, infusions of the plasma expanders, rondex, 10% albumin and polyglucine may be used at a limited volume. The plasma substitute rondex ensures a more favorable hemodynamic and rheological effect, comparing very favourably with other preparations investigated.

Adolescent↗
PubMedDate not supplied

[Hemodynamic reaction in the ultrarapid induction and protection realized with fentanyl].

The hemodynamic response caused by the orthotracheal intubation and also the fentanyl-induced protection were determined in the patients with ultrarapid anesthetic induction. 60 patients were randomly distributed in 3 groups, each of 30 patients: group I, control, with sequential induction, group II, with ultrarapid induction, and group III with ultrarapid induction protected by fentanyl administration. In the patients in the groups II and III the hydrocortisone in the blood, taken 1 minute before induction and 3 minutes after intubation was dosed radioimmunologically. Measurement of the hemodynamic constants showed the increase of the systolic and diastolic AT, and of the pulse during laryngoscopy and in the first two minutes after intubation in all the patients investigated. The hemodynamic response was stronger in the lot with rapid induction, with important differences in comparison with the group with sequential induction. In the IIIrd group, the previous injection with fentanyl, 5 mcg/kg led to a less intense hemodynamic response to laryngoscopy and intubation, close to that of the control group. Likewise, the injection of the anesthetic was followed by an important decrease in the plasmatic hydrocortisone in comparison with the preinduction values.

Adult↗