Abstract
We assessed muscle performance of the newborn heart by examining left (LV) and right (RV) ventricular myocardial mechanics in 18 open chested lambs (ages 1-40 days) anesthetized with alpha chloralose and instrumented with aortic and pulmonary artery flow probes and pressure catheters and high-fidelity LV and RV microtransducers. In each animal, ventricular pressure (VP) and its first derivative (dp/dt) were recorded from both ventricles. To obtain measurements of contractile state of LV and RV, pressure-velocity curves were constructed relating: 1) contractile element velocity of shortening, VCE =(dp/dt)/(32·IP), to total isovolumic pressure (IP), to obtain Maximal velocity of contractile element shortening (Vmax); and 2) contractile element velocity of shortening, VCE=(dp/dt)/(32·DP), to developed pressure (DP=IP-end-diastolic pressure) to obtain VCE10. Vmax values are presented in the table; DP-obtained Vmax Values (VCE10) paralleled these results:
This data demonstrates an increased LV contractile state in the newborn lamb which exceeds Vmax values for the adult sheep LV and declines with maturation. In contrast, the RV shows a lower contractile state which approximates that of the adult sheep RV and does not change with age. (Sponsor: F.H. Adams)
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Riemenschneider, T., Mason, P., Burks, D. et al. CARDIAC MUSCLE PERFORMANCE IN LAMBS: DISPARITY BETWEEN CONTRACTILE ELEMENT VELOCITY OF LEFT AND RIGHT VENTRICLES. Pediatr Res 11, 398 (1977). https://doi.org/10.1203/00006450-197704000-00176
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DOI: https://doi.org/10.1203/00006450-197704000-00176