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At least 19 recordsLinked to original sources
PubMed1992

Ejecting volume, filling volume and stroke volume gains: new indexes of inotropism and lusitropism.

We propose new indexes to evaluate the effects of ventricular inotropism and lusitropism on stroke volume. The end-systolic pressure-volume relationship (ESPVR) or its slope (Emax) has been employed to assess ventricular inotropism. The end-diastolic pressure-volume relationship (EDPVR) or compliance has been used to express ventricular diastolic properties or lusitropism. However, their net effect on stroke volume under a given set of preload and afterload pressures has not quantitatively been evaluated. Ejecting volume gain (Ge) was proposed to quantify the inotropic effect on stroke volume by the change in end-systolic volume between the two ESPVR curves obtained before and during an inotropic intervention at a specified ejecting pressure. Ge is a function of afterload pressure. Filling volume gain (Gf) was proposed to quantify the lusitropic effect on stroke volume by the change in end-diastolic volume between the two EDPVR curves before and during a lusitropic intervention at a specified filling pressure. Gf is a function of preload pressure. The net effect of these inotropic and lusitropic effects on stroke volume at these specified preload and afterload pressures can be expressed by the sum of Ge and Gf. We call this sum stroke volume gain (Gsv). Gsv is a function of preload and afterload pressures. Using representative examples, we demonstrate that these new indexes are conceptually useful to quantitatively understand changes in the pumping ability of the heart under simultaneous inotropic and lusitropic effects as a function of ejecting and filling pressures.

Animals↗
PubMed1989

The regulation of the ratio of the cardiopulmonary blood volume to stroke volume in sheep.

Volume expansion with dextran was used in unanaesthetised sheep to investigate the mechanisms which are responsible for keeping the ratio of the cardiopulmonary blood volume to stroke volume (CPFI) constant under physiological conditions. For animals with heart rates lower than 80, active pulmonary vasoconstriction was mainly responsible for the regulation obtained with volume expansion, while the Starling mechanism was responsible for keeping the ratio constant for animals with heart rates above 79. The involvement of a regulatory mechanism was shown by the absence of large changes in the CPFI after inducing mechanical stress on the cardiopulmonary system as a result of experimental hypertension. Results obtained with receptor blockade showed that active pulmonary vasoconstriction may be the result of a reflex mechanism with parasympathetic efferents. It is suggested that the receptors for this reflex are situated in the pulmonary arteries and are activated by the pressure changes as a result of heart contractions.

Adrenergic alpha-Antagonists↗
PubMed1977

Monitoring of pulmonary fluid volume and stroke volume by impedance cardiography in patients on hemodialysis.

Changes of intrathoracic fludi volume during maintenance therapy with hemodialysis were studied in ten patients with the aid of impedance cardiography. It was found that there was a statistically significant correlation between the decrease in body weight and the increase in basic thoracic impedance in the individual patients, but the values differed considerably from one patient to another. Therefore, comparison of sequential measurements is feasible only in one and the same patient. Out of 16 patients with overhydration undergoing dialysis, the stroke volume could not be determined by impedance cardiographic studies in eight, owing to the abnormal morphology of the dZ/dt curve. Moreover, because the basic thoracic impedance was not constant during treatment, the calculated changes in stroke volume did not appear to be reliable. This has to be taken into account when repeated measurements are made under clinical conditions. In some of the patients, the dZ/dt curve displayed interesting anomalies, probably resulting from hemodynamic alterations. The diagnostic meaning of these features is not yet known.

Adult↗
PubMedDate not supplied

Influence of combined administration of ethyl alcohol with caffeine and hydroxyzine on cardiac minute volume and stroke volume in rabbits.

The effect of combined administration of ethyl alcohol with caffeine and hydroxyzine on cardiac volume and vascular resistance was studied. Combined administration of these compounds diminished cardiac stroke volume and minute output and increased general vascular resistance. Simultaneous administration of ethanol with caffeine and hydroxyzine exerts an unfavorable effect on haemodynamics of circulatory system.

Animals↗
PubMed1989

[Accuracy of the rheographic method of evaluating stroke volume].

The results of stroke volume determination by means of integral tetrapolar body rheography (ITBR) and M-echocardiography were compared in 78 individuals, while Doppler cardiography was used as the reference method. Fairly high accuracy of stroke volume measurement by ITBR and its advantages over echocardiography, particularly the possibility of calculating the stroke volume irrespective of the heart size, are demonstrated. The accuracy of the ITBR determination declines in patients with severe heart failure.

Adolescent↗
PubMed1992

Reliability of Doppler echocardiographic stroke volume measurement.

To evaluate the accuracy and utility of the echocardiographic Doppler method of determining the stroke volume, the stroke volume was measured in 64 instances in 15 patients and compared to the simultaneous thermodilution stroke volume determinations. Stroke volume, varied by atrial pacing at various heart rates, was calculated noninvasively by the product of the cross-sectional area of the aortic orifice determined by echocardiography and the flow velocity integral measured by continuous wave Doppler. While the cardiac output was increased moderately by atrial pacing, the stroke volume was decreased in relation to the increase in the heart rate. The stroke volume calculated by the echo-Doppler method exhibited a significant linear relationship to the stroke volume determined by thermodilution (r = 0.84) and to the cardiac output (r = 0.75, p less than 0.01). Inter-observer and intra-observer variability was 7 +/- 4% and 5 +/- 4%, respectively. The noninvasive echo-Doppler method of estimating the stroke volume is concluded to be accurate, specifically, to be comparable to the values obtained by thermodilution and with a low inter- and intra-observer variability.

Adult↗
PubMed1977

Effect of high-altitude exposure for 10 days on stroke volume and cardiac output.

Resting stroke volume and cardiac output of 50 normal healthy sea-level residents (group A) were estimated by the noninvasive technique of electrical impedance plethysmography. They were then airlifted to an altitude of 3,658 m and serial estimations carried out at 0-4 h and 5-8 h and on the 2nd, 3rd, 4th, 5th, and 10th days. The subjects were brought back to sea level and studied for up to 5 days. Thirty permanent residents of high altitude (group B) and sixteen lowlanders temporarily resident at high altitude (group C) were also subjected to similar studies. It was found that resting stroke volume and cardiac output of group A started falling immediately on arrival at high altitude, reached the minimum on the 3rd day and tended to improved on the 4th and 5th day, but showed a secondary fall on the 10th day. The reduction in stroke volume in this group was not fully compensated by tachycardia. On return to sea level the cardiac output normalized immediately, the stroke volume on the 2nd day. At sea level goup A had values similar to group B and at high altitude to group C.

Adult↗
PubMed1991

Heart rate-right ventricular stroke volume relation with myocardial revascularization.

Whether increasing pacing frequency in cardiac surgical patients effectively improves right ventricular cardiac index depends on the interrelationships between heart rate, stroke volume index, and end-diastolic volume index. If an inverse relation exists between heart rate and right ventricular volume then the decrease in right ventricular ejection fraction described after bypass may be due, in part, to changes in heart rate. We evaluated the effects of pacing at 80, 95, and 110 beats/min using a thermodilution volumetric catheter in 16 patients undergoing myocardial revascularization. End-diastolic volume index, stroke volume index, and stroke work index were significantly greater after bypass than before bypass, whereas right ventricular ejection fraction remained constant. Before and after bypass, sequentially increasing pacing frequency from 80 to 110 beats/min decreased stroke volume index by 28% to 35% (p less than 0.001), end-diastolic volume index by 12% to 14% (p less than 0.001), and right ventricular ejection fraction by 18% to 24% (p less than 0.001). Right ventricular performance, assessed by comparing the stroke volume index to end-diastolic volume index and stroke work index to end-diastolic volume index relations generated during pacing, was not altered by bypass. We conclude that sequentially increasing heart rate from 80 to 110 beats/min fails to improve stroke volume index and consequently cardiac index before or after cardiac operations. Intraoperatively, in patients with normal left ventricular function, increasing pacing frequency decreases right ventricular ejection fraction due to simultaneous reductions in stroke volume index and end-diastolic volume index.

Adult↗
PubMed1976

Interaction of interval-force relationship with aortic pressure and stroke volume.

The modification by aortic pressure and stroke volume of the response in cardiac performance to increases in heart rate (interval-force relationship) has not been previously studied. To investigate this interaction, 30 adrenergically blocked anesthetized dogs on right heart bypass were studied. At constant low aortic pressure and stroke volume, increasing heart rate (over the entire range 60-180) is associated with a continuously increasing stroke power, decreasing systolic ejection period, and an unchanging left ventricular end-diastolic pressure and circumference. At increased aortic pressure or stroke volume at low rates (60-120), increases in heart rate were associated with an increased performance. However, at increased aortic pressure or stroke volume at high rates (120-180), increases in heart rate were associated with a leveling or decrease in performance. Thus, an increase in aortic pressure or stroke volume results in an accentuation of the improvement in cardiac performance observed with increases in heart rate, but this response is limited to a low heart rate range. Therefore, the hemodynamic response to given increases in heart rate is critically dependent on aortic pressure and stroke volume.

Animals↗
PubMed1976

Acute alterations in stroke volume during exercise at 3,100 m altitude.

Following 3 weeks exposure to an altitude of 3,100 m, the cardiac output response to upright submaximal exercise was examined in 3 healthy subjects breathing ambient air and breathing 60% oxygen. The procedure allowed acute alteration of the 2 conditions within a single testing period of 30 min, 60% oxygen breathing either preceding or following breathing ambient air. Cardiac output was also measured in two of the subjects during maximal exercise under these two conditions. Administration of the high oxygen inspirate during exercise had little effect on the level of cardiac output but resulted in an immediate bradycardia and a dramatic increase of approximately 16% in stroke volume. Stroke volumes during maximal exercise were also increased by approximately 10% by the administration of high oxygen. It is suggested that the condition of decreases exercise stroke volume which develops with chronic exposure to altitude may be largely the result of diminished myocardial contractility stemming from a condition of myocardial hypoxia.

Altitude↗
PubMed1990

Comparative accuracy of Doppler echocardiographic methods for clinical stroke volume determination.

Numerous Doppler echocardiographic methods to measure stroke volume have been proposed in experimental or clinical studies, but their relative accuracy in patients compared with an invasive reference standard remains uncertain. Accordingly, we compared Doppler with thermodilution stroke volume measurement in 18 hospitalized patients, 16 with an acute manifestation of coronary artery disease and two with chronic cardiomyopathies. Doppler time-velocity integrals were measured by darkest line (modal velocity) and the leading edge (maximal velocity) techniques at the aortic annular plane, the mitral orifice, and the mitral annular plane. Two-dimensional echocardiography was used to measure cross-sectional areas (M-mode-corrected at the mitral orifice). The combination of aortic annular cross-sectional area and the leading edge technique of measuring the time-velocity integral of blood flow at this site provided the most accurate measure of stroke volume (r = 0.87, p less than 0.0001, standard error of estimate = 11 cm3; mean difference from thermodilution = 2.8 ml +/- 8.9 ml, p = NS). It also resulted in the most accurate measurement of cardiac output (r = 0.88, p less than 0.0003; mean difference from thermodilution = 0.11 L/min +/- 0.69 L/min, p = NS). Other methods yielded values that correlated less closely and deviated systematically from thermodilution measurements. We therefore conclude that of the six common methods evaluated, the aortic annular leading edge method measures stroke volume with the best accuracy and is most suitable for clinical application.

Adult↗
PubMed1989

[Reproducibility of the Doppler spectrum of the left ventricular stroke volume].

The left ventricular stroke volume was determined in 15 healthy male volunteers of the same age (21-23 yrs). The systolic function was characterized by six, the diastolic function by five parameters. The diameter and the cross-sectional areas of the outflow tract were determined. Intraobserver, interobserver and day-to-day variability of these parameters were investigated. The reproducibility was tested by 4 statistical methods. The significance of the differences between the mean values was determined, as well as the percentual difference of the mean values and of the variation coefficients. Linear regression analysis was done and the correlation coefficient was determined for each parameter. The variation coefficient could be regarded as the best statistical method for characterizing the reproducibility. Thus the simplest, directly measured Doppler parameters gave the best reproducibility. The reproducibility of the complex, calculated parameters was poorer. Comparing the intra- and interobserver reproducibility error, the former one was less.

Adult↗
PubMed1975

Measurement of stroke volume from pulmonary artery pressure record in man.

Stroke volume was determined from the pulmonary artery pressure record by application of the pulse contour method. Pulmonary artery pressure records were obtained in 17 patients using a high fidelity catheter-tip pressure transducer and simultaneous measurements of cardiac output were obtained from indicator dilution curves. The formula used was SV = KP sa (i plus T s/Td) where Psa is the planimetered area beneath the systolic portion of the pulmonary artery pressure curve. Ts and Td are the durations of systole and diastole, and K is a constant. Stroke volume was altered by isometric handgrip exercise and/or pharmacological agents in 15 patients. Serial measurementswere made in 2 patients in acute pulmonary oedema after myocardial infarction. Comparison of a wide range of values of stroke volume by the pulse contour method with those obtained from dye dilution curves showed a good correlation (r plus 0.97, P smaller than 0.001) regression line y = 1.01 times - 0.47. Measurement of stroke volume from the pulmonary artery pressure contour is a technique of potential value in serial haemodynamic monitoring.

Blood Pressure↗
PubMed1987

In utero ventilation with oxygen augments left ventricular stroke volume in lambs.

1. In order to determine mechanisms for increased stroke volume at birth, left ventricular function was investigated in eight fetal lambs during in utero pulmonary ventilation. At surgery fetuses were prepared with a tracheal tube, aortic electromagnetic flow sensor, and carotid, jugular, pericardial and left atrial catheters. 2. After 8.3 +/- 1.5 (mean +/- S.D.) post-surgery days and at 137 +/- 3 days gestation, haemodynamic values were obtained before and during pulmonary ventilation in utero. 3. During ventilation, O2 content increased from 7.3 +/- 2.1 to 14.7 +/- 2.7 ml dl-1 (P less than 0.001), right atrial pressure from 3.0 +/- 1.3 to 4.5 +/- 1.6 mmHg (P less than 0.05), left atrial pressure from 2.5 +/- 1.2 to 10.2 +/- 3.7 mmHg (P less than 0.001), left ventricular stroke volume from 1.1 +/- 0.4 to 1.9 +/- 1.2 ml kg-1 (P less than 0.05), and heart rate from 160 +/- 21 to 183 +/- 11 beats min-1 (P less than 0.05). 4. During O2 ventilation, left ventricular function curves relating stroke volume to left atrial pressure were shifted upward. 5. O2 ventilation produced rapid, reversible increases in left ventricular stroke volume which approximate increases in stroke volume at birth.

Animals↗
PubMed1986

Echocardiographic measurement of left ventricular stroke volume in newborn infants: a correlative study with pulsed Doppler and M-mode echocardiography.

Noninvasive monitoring of stroke volume by pulsed Doppler echocardiography is an important recent advance in neonatal care. Using this technique, we assessed stroke volume in 112 healthy neonates (birth weight 780-5350 g, menstrual age 27-42 weeks). Stroke volume increased with advancing birth weight (r = +0.93) and gestational age (r = +0.90). Mean stroke volume per kilogram body weight (1.77 +/- 0.28 ml/kg) was constant throughout the study population. Doppler-derived stroke volumes correlated linearly with left ventricular dimensions in diastole and in systole. Stroke volumes calculated from left ventricular dimensions using the Feigenbaum and Teichholz equations correlated equally well with Doppler-derived stroke volume values (r = +0.76 and +0.77, respectively).

Birth Weight↗
PubMed1990

Left ventricular stroke volume and output in healthy term infants.

Left ventricular output, left ventricular stroke volume, and systemic vascular resistance were measured noninvasively in 16 healthy term infants at 6 predefined time intervals from less than 15 minutes to 72 hours after birth. The blood flow velocity in the ascending aorta was measured by range-gated Doppler technique and multiplied by the cross-sectional area, measured by 2-dimensional and M-mode echocardiography to yield left ventricular output. Stroke volume was calculated by dividing left ventricular output by heart rate. Mean arterial blood pressure was measured by oscillometric technique and used for calculation of systemic vascular resistance. A poor association between heart rate and left ventricular output was found, whereas there was a very close relationship between stroke volume and left ventricular output. There was also a reciprocal relationship between systemic vascular resistance and stroke volume. This suggests that stroke volume and not heart rate is the main determinant of neonatal left ventricular output and that the low postnatal afterload might strengthen this relationship.

Cardiac Output↗