Impaired diastolic function and disruption of the force-frequency relationship in the right ventricle of newborn pigs resuscitated with 100% oxygen

Transthoracic Echocardiography of the Neonatal Laboratory Piglet

Background: Newborn piglets are commonly used in biomedical research. However, cardiovascular imaging of this species is quite challenging. For point of care diagnostics of heart function transthoracic echocardiography may be used, which appears to differ comparing newborn piglets with adult pigs. To date, there are few data or studies on the feasibility and quality of measurement of functional echocardiographic parameters in very small neonatal piglets. Objectives: To study the feasibility of transthoracic echocardiography in very small newborn piglets in supine position. Methods: In 44 anesthetized and intubated newborn piglets, positioned in supine position [age 32 h (12-44 h), weight 1,220 g (1,060-1,495 g), median (IQR)] transthoracic echocardiography was performed using a point of care ultrasound device (M-Turbo^©, FujiFilm SonoSite BV, Amsterdam, Netherlands), and a standard ultrasound transducer. Results: Using 2D- and M-mode-imaging left- and right-sided heart structures were accessible to transthoracic echocardiography in neonatal piglets. Diameters of the interventricular septum, the left ventricle, and the posterior wall were measured and ejection fraction and shortening fraction was calculated. Both left and right ventricular outflow tract could be imaged, and ventricular filling and systolic function could be evaluated. Furthermore, we were able to assess shunts of fetal circulation, such as patent ductus arteriosus, structure of the heart valves and congenital heart defects including ventricular septal defect. Conclusions: In summary, transthoracic echocardiography is feasible for assessment of cardiovascular function even in very small newborn laboratory piglets in supine position.

From a regional cohort of extremely low birth weight infants: cardiac function at the age of 7 years

BACKGROUND

The long-term impact of prematurity on cardiac structure and function has not yet been fully discovered.

OBJECTIVES

To assess long-term cardiac complications in the regional cohort of extremely low birth weight (ELBW) children born in 2002-2004.

MATERIAL AND METHODS

Eighty-one children born as ELBW infants (91% of the available cohort) with a median birth weight of 890 g (25-75th percentile: 760-950) were evaluated at the mean age of 6.7 years. The control group included 40 children born full-term, selected from one general practice in the district. Echocardiography and 24-hour ambulatory blood pressure measurements (ABPM) were performed. The primary outcome variable was the presence of cardiac complications such as left ventricular hypertrophy (LVH), diastolic dysfunction or systolic dysfunction.

RESULTS

LVH was diagnosed in 4/81 ELBW children and 2/40 control children (p = 1.0). Concentric remodeling was detected in 8 (10%) subjects from the ELBW group and in 2 (5%) from the control group (p = 0.49). There were no patients with diastolic or systolic dysfunction in either group. After having expressed the results of M-mode echocardiography as z-scores for body surface area (BSA), statistically significant differences were observed for right-ventricle dimension in diastole (-1.49 ± 1.25 vs. -0.31 ± 0.91; p < 0.001), LV inner dimension in diastole (-0.53 ± 1.26 vs. 0.13 ± 0.94; p = 0.01) and left atrium (-0.93 ± 1.07 vs. -0.15 ± 1.02; p < 0.01). Heart rate (HR) was significantly faster in ELBW children (92.9 ± 8.4 vs. 86.7 ± 7.4 bpm; p = 0.01 adjusted for BSA) and they also had significantly higher night-time blood pressure [mean (z-score): 1.15 vs. 0.2; p = 0.02] without nocturnal dipping (night-time dipping <10%: 13 (16.7%) vs. 2 (5.2%), p = 0.13).

CONCLUSIONS

No differences were found between the groups in the occurrence of cardiac complications. Ex-preterm ELBW children at age 6 may have a faster HR, smaller cardiac dimensions on echocardiography and higher nocturnal blood pressure. The clinical relevance of these findings is unknown.