Cerebral blood flow velocity wave form as an indicator of neonatal left ventricular heart function

A Scoping Review of Cerebral Doppler Arterial Waveforms in Infants

Cerebral Doppler ultrasound has been an important tool in pediatric diagnostics and prognostics for decades. Although the Doppler spectrum can provide detailed information on cerebral perfusion, the measured spectrum is often reduced to simple numerical parameters. To help pediatric clinicians recognize the visual characteristics of disease-associated Doppler spectra and identify possible areas for future research, a scoping review of primary studies on cerebral Doppler arterial waveforms in infants was performed. A systematic search in three online bibliographic databases yielded 4898 unique records. Among these, 179 studies included cerebral Doppler spectra for at least five infants below 1 y of age. The studies describe variations in the cerebral waveforms related to physiological changes (43%), pathology (62%) and medical interventions (40%). Characteristics were typically reported as resistance index (64%), peak systolic velocity (43%) or end-diastolic velocity (39%). Most studies focused on the anterior (59%) and middle (42%) cerebral arteries. Our review highlights the need for a more standardized terminology to describe cerebral velocity waveforms and for precise definitions of Doppler parameters. We provide a list of reporting variables that may facilitate unambiguous reports. Future studies may gain from combining multiple Doppler parameters to use more of the information encoded in the Doppler spectrum, investigating the full spectrum itself and using the possibilities for long-term monitoring with Doppler ultrasound.

Cerebral blood flow velocity and oxygenation correlate predominantly with right ventricular function in cooled neonates with moderate-severe hypoxic-ischemic encephalopathy

The relationship between right ventricular (RV) function and cerebral blood flow (CBF) velocity and cerebral oxygenation was assessed in neonates with hypoxic-ischemic encephalopathy (HIE) treated with therapeutic hypothermia (TH). Echocardiographic, transcranial Doppler, and hemodynamic data from 37 neonates with moderate-severe HIE + TH were reviewed. Twenty healthy newborns served as controls. Cardiac dysfunction in HIE + TH was characterized by a predominant RV dysfunction, with concomitantly reduced CBF velocity. A significant correlation was found between CBF velocity and tricuspid annular plane systolic excursion (TAPSE), RV output (RVO), and stroke volume (SV_RV), as well as with left ventricular output and stroke volume. Brain oxygenation (rSO2) correlated significantly with RVO, SV_RV, TAPSE, ejection fraction, and fractional shortening, whereas cerebral fractional tissue oxygen extraction (FTOEc) correlated with RVO, SV_RV, RV myocardial performance index, and superior vena cava flow. CBF velocity and cerebral NIRS correlations were stronger with parameters of right ventricular performance.Conclusion: CBF velocity and brain oxygenation correlate predominantly with RV function in HIE + TH. This suggests a preferential contribution of RV performance to cerebral hemodynamics in this context. What is Known: • Neonates with hypoxic ischemic encephalopathy frequently exhibit alterations of cardiac function and cerebral blood flow. • These are considered organ-specific consequences of perinatal asphyxia. What is New: • We show that cerebral blood flow velocity and brain oxygenation are correlated predominantly with right ventricular function during therapeutic hypothermia. • This suggests a potential direct contribution of right ventricular performance to cerebral hemodynamics in this context.

Application of Neonatologist Performed Echocardiography in the Assessment and Management of Neonatal Heart Failure unrelated to Congenital Heart Disease

Neonatal heart failure (HF) is a progressive disease caused by cardiovascular and non-cardiovascular abnormalities. The most common cause of neonatal HF is structural congenital heart disease, while neonatal cardiomyopathy represents the most common cause of HF in infants with a structurally normal heart. Neonatal cardiomyopathy is a group of diseases manifesting with various morphological and functional phenotypes that affect the heart muscle and alter cardiac performance at, or soon after birth. The clinical presentation of neonates with cardiomyopathy is varied, as are the possible causes of the condition and the severity of disease presentation. Echocardiography is the selected method of choice for diagnostic evaluation, follow-up and analysis of treatment results for cardiomyopathies in neonates. Advances in neonatal echocardiography now permit a more comprehensive assessment of cardiac performance that could not be previously achieved with conventional imaging. In this review, we discuss the current and emerging echocardiographic techniques that aid in the correct diagnostic and pathophysiological assessment of some of the most common etiologies of HF that occur in neonates with a structurally normal heart and acquired cardiomyopathy and we provide recommendations for using these techniques to optimize the management of neonate with HF.

The myocardial function during and after whole-body therapeutic hypothermia for hypoxic-ischemic encephalopathy, a cohort study

BACKGROUND

Therapeutic hypothermia has become standard treatment for moderate and severe neonatal hypoxic-ischemic encephalopathy (HIE) to reduce cerebral morbidity and mortality. The effect on the heart is incompletely explored.

AIM

To assess the myocardial function during and after whole-body therapeutic hypothermia for HIE.

STUDY DESIGN

Observational cohort study.

SUBJECTS

Forty-four infants with HIE cooled for 72hours were compared with 48 healthy term infants and 20 normothermic infants with HIE.

OUTCOME MEASURES

Tissue Doppler deformation indices of myocardial function (peak systolic strain, peak systolic strain-rate, early diastole strain-rate and strain-rate in atrial systole) during (days 1 and 3) and after (day 4) therapeutic hypothermia.

RESULTS

On days one and three all indices in both HIE groups were lower than the corresponding indices in the healthy infants. The two HIE groups had similar indices, except peak systolic strain-rate on days 1 and 3 and strain-rate in atrial systole on day 1. All strain-rate indices improved from day 3 to 4 (after rewarming) in the cooled group and achieved similar values to those in healthy infants on day 3. All indices were higher in the cooling-group after rewarming than in the normothermic infants with HIE on day 3, except early diastolic strain-rate.

CONCLUSIONS

Infants with HIE had similarly impaired myocardial function during days 1-3 whether normothermic or hypothermic. The myocardial function improved significantly at day 4 (after rewarming), approaching the day 3 levels in the healthy neonates.

Myocardial performance assessment in neonates by one-segment strain and strain rate analysis by tissue Doppler - a quality improvement cohort study

OBJECTIVES

To investigate one-segment strain and strain rate indices as measures of myocardial performance in asphyxiated term neonates.

DESIGN

Quality improvement cohort study.

SETTING

Newborns admitted to a neonatal intensive care unit at a Norwegian University Hospital for perinatal asphyxia and non-asphyxiated newborn recruited from the maternity ward at the same hospital.

PARTICIPANTS

Twenty asphyxiated and 48 non-asphyxiated term neonates.

PRIMARY OUTCOME MEASURE

Strain and strain rate indices and repeatability measures. One-segment longitudinal strain and strain rate by tissue Doppler were assessed on days 1, 2 and 3 of life in nine heart walls. Repeatability was compared against measurements from two-segment analyses previously performed in the same images.

RESULTS

The 95% limits of agreement were significantly better for the one-segment than two-segment repeatability analyses, the inter-rater peak systolic strain (PSS) was (-3.1, 3.3) vs (-11.4, 18.3)%, the inter-rater peak systolic strain rate (PSSR) was (-0.38, 0.40) vs (-0.79, 1.15)/s, the intra-rater PSS was (-2.5, 2.6) vs (-8.0, 9.8)% and the intra-rater PSSR was (-0.23, 0.25) vs (-0.75, 0.80)/s (p<0.05). The myocardial performance was lower in the asphyxiated neonates (indices closer to zero) than in the non-asphyxiated neonates, PSS was -17.8 (0.6) (mean (SEM)) vs -21.2 (0.3)%, PSSR -1.43 (0.08) vs -1.61 (0.03)/s, early diastolic strain rate 1.72 (0.11) vs 2.00 (0.11)/s and strain rate during the atrial systole 1.92 (0.17) vs 2.27 (0.10)/s (p<0.05), despite no difference in fractional shortening (29.0 (0.5) vs 29.1 (1.0)%) (p>0.05).

CONCLUSIONS

One-segment strain and strain rate assessed the reduced myocardial performance in asphyxiated neonates with significantly improved reproducibility as compared with two-segment analysis and was therefore more feasible than two-segment analyses for assessment of myocardial performance after perinatal asphyxia.

Longitudinal strain and strain rate by tissue Doppler are more sensitive indices than fractional shortening for assessing the reduced myocardial function in asphyxiated neonates

The function of the heart was studied in 20 asphyxiated term neonates by measuring the longitudinal peak systolic strain and peak systolic strain rate by tissue Doppler in 18 segments of the heart on days 1, 2, and 3 of life. The fractional shortening was assessed at each examination as well. Measurements were compared against measurements in 48 healthy term neonates examined by the same protocol. The function of the heart was lower in the asphyxiated neonates - peak systolic strain (mean (95% confidence interval) -19.4% (-20.4, -18.5), peak systolic strain rate -1.65 (-1.74, -1.56) per second) than in the healthy term neonates (peak systolic strain -21.7% (-22.3, -21.0), peak systolic strain rate -1.78 (-1.84, -1.74) per second; p < 0.001). Fractional shortening was similar in the asphyxiated (29.2% (26.8, 31.5)) and healthy term neonates (29.0% (27.9, 30.1); p = 0.874). The peak systolic strain differed significantly between the asphyxiated and healthy term neonates for the left basal and right basal groups of segments (p < 0.05) but not for the left apical, right apical, septum apical, or septum basal groups of segments. The peak systolic strain rate differed significantly only for the septum apical group of segments. The differences were largest on the second day of life. Measurements were similar in asphyxiated neonates with elevated and normal cardiac troponin T levels. The peak systolic strain and strain rate were in this study more sensitive indices than fractional shortening for assessing the reduced myocardial function in asphyxiated term neonates.

Cardiovascular impact of dobutamine in neonates with myocardial dysfunction

OBJECTIVE

To study effects of dobutamine on cardiac functional parameters, cerebral, mesenteric and renal blood flow in preterm neonates with myocardial dysfunction.

STUDY DESIGN

Prospective evaluation of Doppler sonographically measured left ventricular systolic time intervals, stroke volume (SV), cardiac output (CO), and blood flow parameters of anterior cerebral artery (ACA), superior mesenteric artery (SMA) and renal arteries (RA), before, after 20 min and 8-10 h of dobutamine treatment in 20 neonates (gestational age 29.6+/-4.4 weeks, birth weight 1450+/-609 g and postnatal age 2+/-2.1 days). Dobutamine was given in a mean dosage of 9.1+/-1.1 microg/kg.

RESULTS

After 20 min SV increased from 1.71+/-0.5 ml to 2.12+0.57 ml/kg, CO from 223+/-76 to 290 ml/kg/min. A shortening of left ventricular pre ejection period from 86+/-12 to 66+/-13 ms and of the ratio of pre-ejection period/ejection time from 0.52+/-0.12 to 0.40+/-0.11 were observed. Blood flow velocities of ACA increased after 8-10 h: peak systolic flow velocity (PSV) from 19.0+/-6 to 29.6+/-7.1 ms, end diastolic velocity (EDV) from 2.9+/-2.6 to 12.7+/-11.3 ms. PSV of SMA increased from 32.5+/-4.7 to 49.7+/-7.8 ms after 8-10 h, EDV from 8.9+/-8 ms to 20.6+/-6.1 ms. PSV of RA increased from 18.2+/-6.1 ms to 39.9+/-4.8 ms, EDV from 2.2+/-1.2 to 8.2+/-2.1 ms after 8-10 h. The pulsatility indices decreased significantly after 8-10 h: ACA from 2.3+/-0.6 to 1.4+/-0.5, SMA from 1.7 to 1.2 and RA from 2.57 to 1.57.

CONCLUSION

Dobutamine improves the cardiac functional parameters already after 20 min and has an influence on the blood flow parameters of ACA, SMA and RA 8-10 h after administration in neonates with myocardial dysfunction.

Cardiac adaptation in small for gestational age neonates after prenatal hemodynamic disturbances

BACKGROUND

Small for gestational age neonates with prenatal hemodynamic disturbances are at increased risk for neonatal morbidity. Investigations of fetal cardiac function have proved some functional impairments. The aim of the study was to investigate postnatal cardiac adaptation in these neonates in comparison with neonates without prenatal hemodynamic impairments.

METHODS AND RESULTS

Forty-one neonates with prenatal hemodynamic disturbances and 40 neonates with undisturbed prenatal hemodynamics were observed during the first 5 days of life. Doppler sonographic measurements of left ventricular time intervals, stroke volume, cardiac output and the incidence of patent ductus arteriosus were obtained in all neonates of both groups. Heart rate and blood pressure were recorded simultaneously.

RESULTS

A higher incidence of patent ductus arteriosus and a diminished stroke volume, but increased cardiac output, based on a significantly increased heart rate, were determined in SGA neonates with prenatal hemodynamic disturbances. In contrast, systolic left ventricular time intervals were not changed in these neonates, as expected.

CONCLUSIONS

The described findings could be signs of persistent hemodynamic impairments in growth-retarded neonates with prenatal disturbed hemodynamics. The neonates revealed a reduced ability to compensate the prenatal hemodynamic disturbances. This aspect should be included in the discussion of perinatal management in cases of severe growth retardation.