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At least 271 records · Page 15Linked to original sources
PubMed1978

[Cardiovascular changes during ethanol-tocolysis].

The cardiovascular effects of an intravenous infusion of a 5% ethanol-10% fructose-solution was examined in 10 healthy late pregnant women with the method of quantitative sphygmometry. There are insignificant changes of the arterial pressure, but increase of stroke volume, cardiac output, work and power and a decrease of total peripheral resistance. In spite of these favourable hemodynamic alterations, particularly the constant heart rate, ethanol should be used only for a short-time-tocolysis.

Adult↗
PubMedDate not supplied

[Effect of lactin and thyroidin on systemic hemodynamics and oxygen regimen of the body in hemorrhagic shock].

The experiments on 28 unconscious male cats revealed the antishock effect of thyroidin (0.15 g/kg, intraperitoneally) through the positive myocardial inotropic effect, which, in addition to enhanced total peripheral vascular resistance, caused elevated blood pressure (BP). The antishock effect of thyroidin was substantially enhanced after a single intravenous injection of lactin (50 U/kg), as expressed by the recovery of plasma volumes, cardiac output at the expense of cardiac systolic volumes, and elevated BP. Thyroidin may be used only as an ingredient of combined antishock therapy as it induces intensive of oxidative process, as evidenced by higher utilization co-efficient for oxygen and its uptake at the baseline levels in shock, and by short-term elevations of blood temperatures.

Animals↗
PubMed2006

Influence of heart rate and temporal resolution on left-ventricular volumes in cardiac multislice spiral computed tomography: a phantom study.

PURPOSE: We sought to investigate the influence of heart rate and temporal resolution on the assessment of left-ventricular (LV) function with multislice spiral computed tomography (CT). MATERIAL AND METHODS: A dynamic cardiac phantom was repeatedly scanned with a 64-slice CT scanner using a standardized scan protocol (64 x 0.6 mm, 120kV, 770mAs(eff), 330 milliseconds rotation time) at different simulated heart rates, ranging from 40 to 140 beats per minute. Images were reconstructed with an algorithm utilizing data from 1 to 4 cardiac cycles (RR intervals). Ejection fraction (EF), end-systolic, end-diastolic, and stroke volume as well as cardiac output were calculated. Results of the measurements were compared with the real volumes of the phantom. Interscan and intraobserver variability were calculated. RESULTS: Using a monosegmental reconstruction algorithm, the temporal resolution was fixed to 165 milliseconds. With bi-, tri-, and quad-segmental image reconstruction, mean temporal resolution was 128.3 +/- 33.2 milliseconds, 103.3 +/- 49.2 milliseconds, and 87.8 +/- 81.5 milliseconds, respectively. Multisegmental image reconstruction resulted in a lower deviation when comparing measured and real volumes. Using mono-, bi-, tri-, and quad-segmental image reconstruction, the percent deviation between measured and real values for EF was 8.2%, 4.5%, 3.3%, and 3.4%, respectively. Applying multisegmental image reconstruction with improved temporal resolution the deviation decreased with increasing heart rate when compared with mono-segmental image reconstruction. Interscan and intraobserver variability for EF were 1.1% and 1.9%, respectively. CONCLUSION: Enhanced temporal resolution improves the quantification of LV volumes in cardiac multislice spiral CT, enabling reliable assessment of LV volumes even at increased heart rates.

Algorithms↗
PubMed1983

Measurement of cardiac stroke volume by impedance cardiography in the last trimester of pregnancy.

Simultaneous determination of cardiac stroke volume by impedance cardiography and the dye dilution technique was compared in 10 women during the last trimester of pregnancy. Measurements were performed in different body positions to investigate the influence of body position on stroke volume. The correlation coefficient for all measurements was 0.87. Mean stroke volume determined by impedance cardiography was significantly (p less than 001) lower than mean stroke volume calculated by the dye dilution technique. There was no significant difference between the mean change in stroke volume determined by the two techniques during serial measurements. The reproducibility of individual impedance-determined stroke volumes (6.1 ml) did not differ significantly from individual values obtained by dye dilution (9.3 ml). Maximum mean impedance-determined stroke volume was recorded in the left lateral position (83.8 +/- 4.0 ml). Mean stroke volume was significantly (p less than 0.01) reduced in the supine position (17.9%). A smaller (14.4%) reduction was registered in the right lateral position. These changes in stroke volume according to body position were equally evident by both methods. Impedance cardiography is a safe, reliable, non-invasive technique for the measurement of changes in stroke volume during late pregnancy. The ability of impedance cardiography to determine changes in stroke volume was unaffected by changes in body position.

Adult↗
PubMed1991

Arterial vasodilation and cardiovascular structural changes in normotensive rats.

In normotensive rats, the arterial vasodilator minoxidil causes right ventricular hypertrophy (RVH) and eccentric left ventricular hypertrophy (LVH). To assess whether this trophic effect of minoxidil extends to the vasculature and to examine possible mechanisms involved, alterations in cardiac and arterial (superior, large and small mesenteric arteries, carotid and basilar arteries) structure were evaluated in relation to changes in indexes of cardiac volume load and cardiac and arterial sympathetic activity during long-term (35 and 70 days) treatment of normotensive rats with minoxidil alone or in combination with the diuretic hydrochlorothiazide (HCTZ). Minoxidil alone increased LV and RV weights, LV internal diameter, and medial area of the superior mesenteric artery but did not affect any of the other arteries evaluated. When combined with HCTZ, long-term minoxidil caused concentric LVH rather than eccentric LVH and no longer increased the medial area of the superior mesenteric artery. Neither treatment had any persistent effect on blood pressure, heart rate, or plasma catecholamines. However, minoxidil significantly increased cardiac and arterial (superior and large mesenteric artery) norepinephrine turnover rates, cardiac filling pressures, and plasma and blood volumes. When combined with HCTZ, short-term (1 wk) minoxidil still increased cardiac filling pressures. However, intravascular volume expansion during chronic treatment was significantly attenuated. These results suggest that chronic cardiac volume load appears to determine the type of cardiac hypertrophy induced by a nonhemodynamic mechanism (possibly cardiac sympathetic activity) activated by minoxidil. Intravascular volume expansion or increased arterial flow appears to be responsible for medial hypertrophy of the superior mesenteric artery, but absence of a trophic response in other arteries suggests that another, local mechanism contributes.

Animals↗
PubMed1983

Maternal blood volume and cardiac output during pregnancy: a hypothesis of endocrinologic control.

During the course of gestation the increase of maternal total blood volume and cardiac output may result from two mechanisms acting in concert: 1) the production of several hormones by the fetus and the placenta, and 2) the uteroplacental circulation acting as an arteriovenous shunt. Plasma volume appears to increase as a consequence of renal Na+ reabsorption and water retention, which result from increased aldosterone production via the renin-angiotensin system, as a consequence of placental estrogen production. This estrogen production in turn results from increasing availability of the estrogen substrate dehydroepiandrosterone (chiefly from the fetal adrenal gland). Erythrocyte volume increases as a consequence of the erythropoietic effect of placental chorionic somatomammotropin, progesterone, and perhaps prolactin. In addition, maternal blood volume increases in response to the uteroplacental circulation functioning as a low-resistance circuit. In turn, this increases cardiac output and nutrient delivery for further growth of the products of gestation. Thus there may exist a feedback mechanism whereby fetal growth and, in particular, increasing steroidogenesis by the developing fetal adrenal gland result in the maternal cardiovascular adaptations to pregnancy that optimize further fetal development. In certain complications of pregnancy the less-than-normal maternal blood volume increase may result from failure of these mechanisms, while in turn contributing to the further genesis of these disorders.

Animals↗
PubMed2004

Low coronary perfusion pressure is associated with endocardial fibrosis in a rat model of volume overload cardiac hypertrophy.

UNLABELLED: Left ventricular hypertrophy following volume overload is regarded as an example of cardiac remodeling without increased fibrosis accumulation. However, infarction is associated with increased fibrosis within the noninfarcted, hypertrophied myocardium, particularly in the subendocardial regions. It is conceivable to suppose that, as also occurs postinfarction, low coronary driving pressure may also interfere with accumulation of myocardial fibrosis following aortocaval fistula. PURPOSE: To investigate the role of acute hemodynamic changes in subsequent deposition of cardiac fibrosis in response to aortocaval fistula. METHOD: Aortocaval fistula were created in 4 groups of Wistar rats that were followed over 4 and 8 weeks: aortocaval fistula 4 and aortocaval fistula 8 (10 rats each) and their respective controls (sham-operated controls - Sh), Sh4 and Sh8 (8 rats each). Hemodynamic measurements were performed 1 week after surgery. Hypertrophy and fibrosis were quantified by myocyte diameter and collagen volume fraction at the end of follow up. RESULT: Compared with Sh4 and Sh8, pulse pressure, left ventricular end-diastolic pressure, and +dP/dt were higher in aortocaval fistula 4 and aortocaval fistula 8, but -dP/dt was similar. Coronary driving pressure (mm Hg), used as an estimate of perfusion pressure, was lower in aortocaval fistula 8 (52.6 +/- 4.1) than in Sh8 (100.8 +/- 1.3), but comparable between aortocaval fistula 4 (50.0 +/- 8.9) and Sh4 (84.8 +/- 2.3). Myocyte diameter was greater in aortocaval fistula 8, whereas interstitial and subendocardial fibrosis were greater in aortocaval fistula 4 and aortocaval fistula 8. Coronary driving pressure correlated inversely and independently with subendocardial fibrosis (r(2) = .86, P <.001), whereas left ventricular systolic pressure (r(2) = 0.73, P = .004) and end-diastolic pressure (r(2) = 0.55, P = 012) correlated positively and independently with interstitial fibrosis. CONCLUSION: Coronary driving pressure falls and ventricular pressures increase early after aortocaval fistula and are associated with subsequent myocardial fibrosis deposition.

Animals↗
PubMed1977

[Proteins and blood volume after cardiac surgery under ECC and hemodilution].

The variations in protein, bodyweight and circulating blood volume during operation are studied in 18 patients operated under ECC. The frequency of hypovolemia with hypoproteinemia and over hydration of the interstitial medium is confirmed. The prolongation of ECC beyond 120 minutes is accompanied by a considerable reduction in the plasma sector. The frequency of hypovolemia must render the use of diuretics prudent. The existence of hypoproteinemia and interstitial overload suggests the value of albumin perfusions.

Blood↗
PubMed1988

Assessment of stroke volume and cardiac output by Doppler echocardiography.

The authors used the pulse and continuous-wave Doppler technique to perform 51 measurements of stroke volume and cardiac output in 37 persons. Results were compared with those obtained using Fick's principle of thermodilution (immediately subsequent or simultaneous). Regression analysis showed a close correlation between Doppler and haemodynamic values - r = 0.86 for stroke volume and 0.94 for cardiac output (p less than 0.001). Using the paired t-test, the methods did not differ significantly. Standard deviation of Doppler stroke volume values from reference haemodynamic values was 10%, and only two measurements differed by more than 25%. Doppler determination of cardiac output can be therefore recommended as an alternative method in patients with high-quality echo Doppler recordings.

Adult↗
PubMed1980

Relationship of cerebral blood flow to cardiac output, mean arterial pressure, blood volume, and alpha and beta blockade in cats.

The relationship among cerebral blood flow (CBF), blood volume, cardiac output (CO), and mean arterial blood pressure (MABP) at varying levels of arterial CO2 tensions (PaCO2) were studied in 70 normal cats. The CBF was measured from the clearance curve of xenon-133 and CO with a thermal dilution catheter placed in the pulmonary artery. The CBF, CO, and MABP values varied appropriately with changes in PaCO2, confirming the reliability of the preparations and the presence of normal autoregulatory responses. Moderate hypovolemia that did not change MABP did, nevertheless, significantly decrease CO and CBF. In an effort to determine if this decrease in CO and CBF were coupled responses, the effects of beta stimulation, hypervolemia, and alpha and beta blockade were investigated. Propranolol, in a dosage insufficient to change MABP, decreased both CO and CBF. This agent abolished the CO response to elevations in PaCO2 but not the CBF response, making it unlikely that this CBF reduction resulted from impaired cerebral autoregulation. Isoproterenol, which, in contrast to propranolol, does not cross the normal blood-brain barrier, alone or in combination with phenoxybenzamine, produced a 38% and 72% increase in CO, respectively, without a change in CBF. Alpha blockade (no major change in CO) and beta blockage (major decrease in CO) did not significantly effect cerebral autoregulation to changes in MABP from angiotensin. The ability of the brain to resist increases in MABP and CO and maintain normal CBF is explained by normal cerebral autoregulation. However, its vulnerability to modest decreases in blood volume, which cannot be attributed to variations in perfusion pressure, is unexplained but obviously has important therapeutic implications. This may be related to reduction in CO, changes in autonomic activity, or a decrease in the size of the perfused capillary bed.

Adrenergic alpha-Antagonists↗
PubMed1987

[Comparison of Doppler echocardiographic methods of determining cardiac minute volume].

In 40 patients without valvular disease, cardiac output was determined by pulsed Doppler echocardiography and thermodilution simultaneously. The sample volume was located in the center of the mitral valve ring, at the tips of the mitral leaflets and in the left ventricular outflow tract, directly proximal to the aortic valve leaflets. Circular cross-sectional areas of the mitral valve ring, aortic ring and bulbus of the aorta were calculated from the M-mode and two dimensional echocardiographic diameters. The mitral orifice was assumed to be an ellipse with varying short axes, determined as the mean diastolic leaflet separation in the M-mode and a constant long axis, derived from the maximal mitral orifice area or mitral ring diameter. Cardiac output was calculated by multiplying time-velocity integrals with different areas and heart rate. Cardiac output, measured by the thermodilution technique, ranged from 4.0 l/min to 10.2 l/min. Cardiac output determined by the different Doppler methods correlated significantly with the thermodilution measurements. Cardiac output measurements in the left ventricular outflow tract provided the best correlation coefficient (0.93) and a standard error of the estimate of 0.589 l/min, when the circular flow area was derived from the M-mode echo of the aortic ring.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1975

A simple module for on-line computation of stroke volume and cardiac output.

An easily constructed, low-priced, simple, and reliable module to obtain stroke volume and cardiac output by analog integration of aortic blood flow velocity signals is described. Rapid data analysis of physiologic and pharmacologic cardiovascular responses in dogs is greatly facilitated by on line computation of these parameters.

Aorta↗
PubMed1983

Measurement of cardiac stroke volume during cesarean section: a comparison between impedance cardiography and the dye dilution technique.

Simultaneous determination of cardiac stroke volume by impedance cardiography and the dye dilution technique was compared in ten women undergoing elective cesarean section performed under general or epidural anesthesia. The influence of delivery and the anesthetic procedures used on stroke volume determination by the two methods was evaluated and compared. The correlation coefficients for measurements performed before and during anesthesia showed little variation and were largely unchanged after delivery of the child (r = 0.90-0.97). Mean stroke volume determined by impedance cardiography was significantly (P less than 0.001) lower than mean stroke volume calculated from the dye dilution technique. However, there was no significant difference between the mean change in stroke volume determined by the two techniques during serial measurements. Impedance cardiography was found to be a safe, reliable, non-invasive technique for the measurement of changes in stroke volume during cesarean section. The ability of the impedance method to determine changes in stroke volume was unaffected by the anesthetic procedures employed or by delivery of the child.

Anesthesia, Epidural↗
PubMed1990

Radiation effects on left ventricular function and myocardial perfusion in long term survivors of Hodgkin's disease.

We evaluated systolic and diastolic indices of left ventricular performance by radionuclide angiocardiography and myocardial perfusion with exercise/rest thallium scintigraphy in 16 patients previously irradiated for Hodgkin's disease. These commonly used indices of left ventricular (LV) performance included LV ejection fraction (LVEF) as a measure of systolic function, and LV peak filling rate (PFR) as a measure of diastolic function. The presence of coronary artery disease (CAD) was evaluated by ECG treadmill testing (13 patients) and by quantitative planar thallium scintigraphy (12 patients). Patients were 16-38 years old (mean 24.9 +/- SD 6.2) at the tim eof irradiation, and were evaluated 2.5-21.5 years (mean 9.3 +/- 6.3) after radiation therapy (RT). RT was delivered with beam energies of 2-18 MV, equally weighted AP-PA mantle fields with both fields treated daily for most patients (13 patients), and fraction sizes of 1.5-2.0 Gy. Six patients received radiation to th entire cardiac volume, most commonly via left-sided partial transmission lung blocks (PTLB). Patient data were analyzed according to the volume of heart treated. Individuals who had the entire cardiac volume irradiated were assigned to group I (N = 6), and those patients who had some portion of the heart shielded throughout treatment comprised group II (N = 10). In this series, no perfusion defects were evident in either group by quantitative planar thallium scintigraphy. Mean LVEF for all patients studied was 60% (normal LVEF greater than or equal to 50%). Patients in group I had a lower mean LVEF than those in group II, 55 +/- 4% versus 63 +/- 6% (p = 0.01). Mean PFR for all patients studied was normal at 3.5 EDV/sec (normal PFR greater than or equal to 2.54 EDV/sec). Patients in group I had a lower mean PFR than those in group II, 3.0 +/- 0.6 vs 3.8 +/- 0.7 EDV/sec (p = 0.04). Thus, patients irradiated to large cardiac and pulmonary volumes had lower LVEF and PFR within the normal range compared to patients who had some portion of the cardiac volume shielded. These differences are statistically significant in the relatively small groups studied but do not appear to be associated at the present time with clinically significant effects.

Adolescent↗
PubMed1980

[Comparative evaluation between the impedance method and the Fick method for determining cardiac minute volume].

The authors determined the minute heart volume, according to Fick method with right cardiac catheterization of 20 healthy youths. With the comparison of the results obtained, the differences were within the limits of +/- 10, and in almost half of the examined-- +/- 5%. The relatively small discrepancies in the values obtained, suggest that the impedence-method proves to be a reliable method for bloodless determination of minute heart volume.

Adolescent↗