Postnatal Left Ventricular Contractility in Very Low Birth Weight Infants

Takahashi, Yosuke; Harada, Kenji; Kishkurno, S.; Arai, Hirokazu; Ishida, Akira; Takada, Goro

doi:10.1007/s002469900127

Cited by 53 publications

(40 citation statements)

References 21 publications

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“…For this reason, in this study we decided to use direct preload independent measures of myocardial contractility that account for afterload to directly measure the response of the left ventricle to varying after-loads in a population of infants, many of who developed low SBF as measured by SVC flow. It has previously been reported that preterm infants have lower myocardial contractility than term infants at 6 h of age (9). However, the relationship to SBF and response to inotropes has not been reported in extremely preterm infants.…”

Section: Discussionmentioning

confidence: 87%

“…A steeper negative slope of the regression line of the relationship indicates a more rapidly reducing mVcfs in response to increasing LV stress, or reduced myocardial contractility (4,8). Preterm infants have been documented to have reduced LV contractility in the first days after birth compared with term infants (9), although the relationship to low blood flow states has not been reported. In addition, the effects on myocardial contractility of commonly used inotropes in preterm infants have not been measured in infants with low flow in the first day.…”

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confidence: 99%

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Left Ventricular Contractility in Extremely Premature Infants in the First Day and Response to Inotropes

2007

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ABSTRACT:The aim was to assess myocardial contractility in infants born Ͻ30 wk gestation developing low systemic blood flow (SBF) in the first day, and the effect of dobutamine versus dopamine. Superior vena cava (SVC) flow was used as a measure of SBF at 3, 10, and 24 h (n ϭ 106). Infants with low SVC flow randomized to dopamine or dobutamine. Myocardial contractility was determined by the relationship between left ventricular (LV) mean velocity of circumferential fiber shortening (mVcfs) and wall stress. Infants who developed low SVC flow had significantly worse myocardial contractility at 3 h, but not 10 h. At 24 h, low-flow infants had lower than expected mVcfs for any given LV stress. In 37 infants randomized to inotrope, there was no significant difference in contractility at 10 g/kg/min. At 20 g/kg/min (n ϭ 21), dopamine increased whereas dobutamine decreased LV stress. Infants on dobutamine had significantly lower than expected mVcfs for any given LV stress compared with infants on dopamine. Contractility was not improved by either inotrope at either dose. In conclusion, infants developing low SVC flow in the first day have worse myocardial contractility at 3 h. Neither inotrope increased contractility, but dopamine increased LV stress at 20 g/kg/min. E xtremely preterm infants with low brain and upper body blood flow, as measured by SVC flow, in the first day are at increased risk of late peri/intraventricular hemorrhage (1,2), mortality, and subsequent neurodevelopmental impairment (3). Low SVC flow was associated with infants born at lower gestation, with a higher MAP in the first 12 h and a larger diameter DA at 5 h of age (1). Although infants with low SVC flow frequently had normal BP, they had significantly higher calculated UBVR compared with infants with normal flows. However, calculated vascular resistance is not a direct measure of LV afterload. LV stress is affected by LV dimensions, which are affected by preload, and LV wall thickness (4,5).Although LV shortening fraction has been reported to be reduced in shocked and acidotic preterm infants (6), this measure of LV performance does not take preload or afterload conditions into account and has been reported to be unreliable in preterm infants (7). In contrast, the relationship between LV mVcfs and LV wall stress (LV stress) has been used as a preload independent measure of LV contractility that takes into account afterload conditions. Myocardial contraction velocity will fall as afterload increases. A steeper negative slope of the regression line of the relationship indicates a more rapidly reducing mVcfs in response to increasing LV stress, or reduced myocardial contractility (4,8). Preterm infants have been documented to have reduced LV contractility in the first days after birth compared with term infants (9), although the relationship to low blood flow states has not been reported. In addition, the effects on myocardial contractility of commonly used inotropes in preterm infants have not been measured in infants with low flow in the firs...

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Section: Discussionmentioning

confidence: 87%

mentioning

confidence: 99%

Left Ventricular Contractility in Extremely Premature Infants in the First Day and Response to Inotropes

2007

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“…The effect of high airway pressure is not limited to the pulmonary vasculature, with direct compressive effects observed on the newborn heart, resulting in reduced cardiac performance and ventricular output (21,24). This is further complicated by recent studies in preterm animals (25,26) and preterm infants (27,28) demonstrating that the preterm heart, particularly the myocardium, is structurally immature, translating to lower contractility in the days after birth and an inability to cope with increasing afterload.…”

Section: Hemodynamic Consequences Of the Initiation Of Positive Pressmentioning

confidence: 84%

Respiratory support for premature neonates in the delivery room: effects on cardiovascular function and the development of brain injury

et al. 2014

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“…That myocardial contractility may be impaired in preterm infants (15,27) raises the possibility that ductal steal in the first postnatal day may lead to decreased systemic perfusion. However, high-volume ductal shunting occurs into a pulmonary circulation of low resistance, and there is some suggestion from animal studies that even the immature myocardium is able to significantly increase LVO when afterload is low (28).…”

Section: Discussionmentioning

confidence: 99%

“…However, it is possible that the immature myocardium has a limited ability to increase output in the first postnatal day (15). The combination of high-volume ductal shunt without an increase in cardiac output could lead to systemic hypoperfusion.…”

mentioning

confidence: 99%

Does Retrograde Diastolic Flow in the Descending Aorta Signify Impaired Systemic Perfusion in Preterm Infants?

et al. 2008

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High-volume systemic-to-pulmonary ductal shunting occurs frequently in preterm infants and is indicated by diastolic flow reversal in the descending aorta (DAo). We studied the relationship between ductal diameter, diastolic DAo reversal, and left ventricular output (LVO); and superior vena caval (SVC) flow (upper body perfusion) and DAo flow (lower body perfusion) in preterm (Ͻ31 wk) infants. Echocardiographic assessments were performed at 5, 12, 24, and 48 h postnatal age (80 infants, median gestation 28 wk, 1060 g). Incidence of ductal patency fell from 100% at 5 h to 72% at 48 h; incidence of pure systemic-to-pulmonary shunting increased from 66% to 95% of infants with patent ducts. In infants with duct diameter greater than the median, 35-48% of infants had DAo flow reversal. In infants with duct diameter greater than median, DAo reversal was associated with 23-29% increases in LVO at 5-48 h, and 35% decreases in DAo flow volume at 24 -48 h, but no differences in SVC flow. In conclusion, a large duct with left-to-right shunting is common in preterm infants. Retrograde DAo flow is a marker of high-volume shunt, evidenced by increased LVO. Preterm infants with high-volume ductal shunt may have preserved upper body perfusion but reduced lower body perfusion. T he clinical significance of shunting through the patent ductus arteriosus in the premature newborn infant remains uncertain (1-4). It is clear that prolonged patency of the ductus arteriosus is seen in preterm infants with respiratory distress (5), and can be associated with significant volume of systemic-to-pulmonary shunting (6). In addition, prolonged ductal patency is associated with a variety of adverse outcomes in preterm infants (7). However, a causative association between ductal shunting and adverse outcome has not been established (8,9), and clinical trials of therapeutic intervention have not demonstrated reductions in morbidity (1). There is increasing awareness that ductal patency may not be a primary pathologic entity but rather an epiphenomenon of prematurity itself (10).Circulatory impact of ductal shunt depends on the volume of shunt and the ability of the myocardium to produce a compensatory increase in left ventricular output (LVO). It has previously been suggested that in the first postnatal days shunt volume through the ductus would be low due to the relatively balanced pulmonary and systemic arterial pressures at this time (11). However, there is now substantial evidence that pulmonary pressure in surfactant treated infants falls rapidly after birth (12,13). High-volume ductal shunt, as evidenced by reversal of blood flow during diastole in the descending aorta (DAo), has been seen as early as 7 h after birth (8), and may occur days before clinical signs appear (5).LVO has been shown to increase with increased ductal shunting in many preterm infants (14). However, it is possible that the immature myocardium has a limited ability to increase output in the first postnatal day (15). The combination of high-volume ductal shunt...

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Postnatal Left Ventricular Contractility in Very Low Birth Weight Infants

Cited by 53 publications

References 21 publications

Left Ventricular Contractility in Extremely Premature Infants in the First Day and Response to Inotropes

Left Ventricular Contractility in Extremely Premature Infants in the First Day and Response to Inotropes

Respiratory support for premature neonates in the delivery room: effects on cardiovascular function and the development of brain injury

Does Retrograde Diastolic Flow in the Descending Aorta Signify Impaired Systemic Perfusion in Preterm Infants?

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