Frank-Starling relationship as an important determinant of fetal cardiac output

Se, Kirkpatrick; Pitlick, PT; Naliboff, Jay A.; Friedman, WF

doi:10.1152/ajplegacy.1976.231.2.495

Cited by 132 publications

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“…The response differed from that observed in lamb fetuses at the same gestational age (8)(9)(10)(11)(12), but was similar to that seen in full-term newborn (6) and I-wk-old lambs (3)(4)(5)7). Although a Frank-Starling relationship has been demonstrated in the fetal lamb (28), challenging the fetus with a volume load only modestly increases stroke volume above baseline measurements (8)(9)(10)(11)(12). During the saline infusion, there was a change in the distribution of cardiac output; the liver, kidneys, and gastrointestinal tract received a lower percentage of left ventricular output.…”

Section: Discussionsupporting

confidence: 55%

How a Patent Ductus Arteriosus Effects the Premature Lamb's Ability To Handle Additional Volume Loads

et al. 1987

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ABSTRACT. A model of patent ductus arteriosus in premature lambs was created to examine the lamb's ability to handle the volume load imposed by a patent ductus arteriosus and to determine the lamb's ability to handle any additional volume load. Fifteen preterm lambs I133 -C 2 ( 2 SD) days gestation, term 145 days], whose ductal diameter could be regulated with a mechanical occluder, were studied to determine the independent effects of ductus patency and a saline volume load (50 ml/kg over 3 min) on left ventricular output and its distribution. During a saline infusion, preterm lambs with a closed ductus could only increase their stroke volume by 40% above baseline stroke volume. When challenged with a saline infusion, lambs with an open ductus still were able to increase their stroke volume significantly; the maximal increase in stroke volume during the saline load with the ductus open was 70% above baseline stroke volume. W e hypothesize that the associated reduced left ventricular afterload plays a significant role in the preterm lamb's ability to increase its stroke volume when challenged with a patent ductus arteriosus. Even with a patent ductus arteriosus, the lamb still has the ability to handle additional volume loads. (Pediatr Res 22: 531-535, 1987) Abbreviations PDA, patent ductus arteriosus LV, left ventricle QLV, left ventricular output Q pulmonary, pulmonary blood flow Q ductus, ductus arteriosus blood flow Q systemic, systemic blood flow R pulmonary, pulmonary vascular resistance R systemic, systemic vascular resistance R ductus, ductus arteriosus resistance R total, total resistance Hbg, hemoglobin GI, gastrointestinalThe PDA represents a significant stress on the premature cardiovascular system. The extent of this stress depends both on the magnitude of the left to right shunt through the PDA and on the ability of the cardiovascular system to adjust to that shunt. Full-term newborn lambs respond to volume loading with a limited increase in stroke volume, compared with adult sheep. The left ventricle of the full-term newborn lamb is capable of developing greater force than the left ventricle of the preterm lamb (with closed ductus) at comparable filling volume and resistance (6). Several studies have shown that the fetal lamb has a limited ability to increase its stroke volume above its baseline value during an acute volume load (8-12).The limited ability of the developing left ventricle to increase its output during a volume load is caused by some degree of myocardial immaturity (13) as well as by the high resting output needed to supply the demand for oxygen after delivery (14). The high resting level of performance demanded of the newborn heart may exhaust any reserve pumping capacity. The purpose of our study was both to examine the premature lamb's ability to handle the volume load imposed by a PDA and to see how the presence of a PDA alters the lamb's ability to tolerate any additional volume load. METHODSPreparafion. Fifteen mixed breed western time-dated pregnant ewes at 128-133 days ge...

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Section: Discussionsupporting

confidence: 55%

How a Patent Ductus Arteriosus Effects the Premature Lamb's Ability To Handle Additional Volume Loads

et al. 1987

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“…Rudolph and Heymann (6) found a direct relationship between HR and LVO, with very small changes in SV, whereas Kirkpatrick et al (7) showed that LVO was constant over a wide range of HR, indicating a substantial ability of the immature heart to change SV. Both studies were performed in chronically instrumented fetal lambs.…”

Section: Discussionmentioning

confidence: 99%

Relationship between Heart Rate, Left Ventricular Output, and Stroke Volume in Preterm Infants during Fluctuations in Heart Rate

Winberg

Ergander

1992

Pediatr Res

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ABSTRACT. The relationship between changes in heart rate, left ventricular output, and left ventricular stroke volume was studied in 18 preterm infants, with mean gestational age 29 wk (range 26-33 wk) and mean postnatal age 10 d (range 1-21 d). To yield left ventricular output, the blood flow velocity in the ascending aorta was measured by range-gated Doppler technique and multiplied by the aortic cross-sectional area measured by cross-sectional and M-mode echocardiography. Stroke volume was calculated by dividing left ventricular output by heart rate. The individual mean left ventricular output correlated poorly with heart rate ( 3 = 0.17), and, accordingly, there was a closer relationship between stroke volume and left ventricular output. In only four of the 18 infants was a significant correlation between heart rate changes and left ventricular output found. Substantial changes in stroke volume were seen in most infants, and in 1 3 of the 18 infants the changes exceeded 25%. These variations in stroke volume were closely related to left ventricular output. In 15 of the 18 infants, the maximum heart rate change was associated with a stroke volume change in the opposite direction. The group average of the maximum heart rate increase in each individual, 24 bpm (18%), corresponded to a decrease in stroke volume of 0.15 mL.kg-' (9%) (p < 0.05) and an increase in left ventricular output of 22.7 m L min-' .kg-' (9%) (p < 0.05). A reciprocal relationship was seen between afterload and left ventricular output. The findings indicate that the preterm infant has a substantial ability to alter stroke volume and that stroke volume is an important determinant of neonatal left ventricular output. During beat-to-beat fluctuations in heart rate, the stroke volume changes appear to reduce the effect of the heart rate changes on output. (Pediatr Res 31: 117-120,1992 Supported by the Karolinska Institute, the General Maternity Hospital Foundation, the Swedish Society for Medicine, and Sallskapet Barnavird.Studies of the fetal and neonatal heart have provided basic information about the myocardial immaturity on the cellular and subcellular levels. The immature myocardium has been shown to contain more water, less contractile elements per unit weight, and less sarcoplasmic reticulum (1, 2). Furthermore, the cardiac sympathetic innervation is not fully developed at birth (3, 4). In in vitro experiments these differences correspond to reduced compliance and reduced contractile force (1) compared with the mature myocardium. However, the hemodynamic consequences of the myocardial immaturity on the intact circulatory system are, despite extensive investigations, still not clearly delineated. It has been claimed that the fetal heart performs at or near its peak capacity even during normal conditions and has a very limited ability to change (SV) (5, 6). Accordingly, fetal and neonatal cardiac output should be almost entirely dependent on HR. This, however, has been questioned in other fetal and neonatal lamb studies (7-lo), as well as in...

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“…The transducer-tipped catheter (left ventricular) was similarly calibrated and was peri- correlated with body weight during gestation. Kirkpatrick et al 4 and Anderson et al 5 19 noted progressively increasing left ventricular dimensions (semiminor axis) in fetal sheep in which ultrasonic crystals had been implanted for an extended period, and these increases were independent of cardiac rate. Others also noted a correlation between left ventricular end-diastolic volume and body weight in full-term newborn lambs during the first months of life.…”

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confidence: 95%

Left ventricular performance and contractility before and after volume infusion: a comparative study of preterm and full-term newborn lambs.

Baylen¹,

Ogata²,

Ikegami³

et al. 1986

Circulation

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We studied left ventricular performance and contractility after volume loading in lambs at 122 days (group I, n = 9) and 139 days gestational age (group IL, n = 9) and in 8-day-old full-term lambs (group III, n = 7). All were mechanically ventilated; each preterm lamb was treated with surfactant to stabilize pulmonary function and the ductus arteriosus was occluded with an inflated catheter balloon. Cineangiograms, left ventricular and vascular pressures, and the isovolumetric index of contractility, first derivative of left ventricular pressure (dP/dt), were recorded before and after three successive whole blood volume infusions of 10 ml/kg (total 30 ml/kg). The left ventricular enddiastolic volume per kilogram and stroke volume per kilogram increased significantly in all groups after volume infusion; these measurements and heart rate and systemic vascular resistance did not differ significantly between the groups either before or after the infusions. The left ventricular peak dP/dt did not change significantly within the groups during the volume infusions. The left ventricular stroke work was greatest in full-term animals and increased significantly in all groups after volume infusion. Thus, the left ventricles of the preterm and full-term lambs had quantitatively similar Frank-Starling responses and there was no increase in contractility during the infusions of whole blood. However, the left ventricle of the full-term lamb is capable of generating greater stroke work than that of the preterm lamb. These findings may contribute to the understanding of developmental aspects of postnatal circulatory adaptation. Circulation 73, No. 5, 1042No. 5, -1049No. 5, , 1986 IT HAS BEEN suggested that the left ventricle of the premature infant may be less capable than the mature left ventricle of adjusting to transitional circulatory changes required postnatally, such as increasing volume and resistance work.' 2 These conclusions followed from ultrastructural observations and from developmental studies of myocardial contraction in isolated muscle preparations, and from comparative studies of left ventricular performance in the intact fetus and full-term newborn lamb.'-' Until recently developmental studies of postnatal left ventricular performance were not possible in newly born preterm animals, because prematurity was associated with a Now, however, acceptable pulmonary function can be maintained with the combined use of surfactant treatment and mechanical ventilation. 10 The purpose of this study was to characterize developmental aspects of left ventricle pump performance and contractility in surfactant-treated preterm lambs and in full-term lambs under conditions simulating those encountered in the neonatal intensive care setting. Material and methodsWe studied the hemodynamic responses to volume infusions in three groups of preterm and full-term lambs. Group I lambs (n -9) were 122 ± 2 (SD) days gestational age, group II lambs (n = 9) were 139 + 2 days gestational age, and group III (n = 7) consisted of 8 + 3...

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Frank-Starling relationship as an important determinant of fetal cardiac output

Cited by 132 publications

References 0 publications

How a Patent Ductus Arteriosus Effects the Premature Lamb's Ability To Handle Additional Volume Loads

How a Patent Ductus Arteriosus Effects the Premature Lamb's Ability To Handle Additional Volume Loads

Relationship between Heart Rate, Left Ventricular Output, and Stroke Volume in Preterm Infants during Fluctuations in Heart Rate

Left ventricular performance and contractility before and after volume infusion: a comparative study of preterm and full-term newborn lambs.

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