Abstract
We assessed the functional capacity of the chronically afterloaded chick embryo heart. At stage 21, a 10-0 nylon loop was tied around the mid conotruncus narrowing the outflow tract. Control embryos had all procedures except the placement of the band. Embryos were returned to the incubator, and harvested at stage 24, 27, or 29 for hemodynamic and morphologic measurements. We used a servo-null pressure system to measure ventricular peak systolic pressure (PSP), end diastolic pressure (EDP) and dP/dt at base line and during brief conotruncal occlusion. We also measured embryo (edw) and ventricular (vdw) dry weight. We generated indexes of ventricular function: PSP, dP/dt, dP/dt/PSP, and dP/dt/PSP/mg dvw. N-9 for each group. The data (X+SEM) were analysed by t-test. Banding increased ventricular but not embryo weight. For experimental v control prior to occlusion, PSP and dP/dt were higher; eg. stage 29, 4.5±0.2 v 3.4±0.1 mmHg, 94±8 v 66±7 mmHg/s (p<0.05) but EDP was unchanged, 0.9±0.1 v 0.8±0.1 mmHg (p>0.05). During conotruncal occlusion PSP, EDP, dP/dt increased in both groups. At stage 29, occluded dP/dt/PSP, 19±1 v 19±2 mmHg/s/mmHg were similar but occluded dP/dt/PSP/mg dvw was less in the afterload group: 74±13 v 138±28 mmHg/s/mmHg/mg (X±95%CI). Thus, as ventricular mass increased to meet functional demands, this index of ventricular functional reserve decreased.
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Clark, E., Hu, N. & Zahka, K. VENTRICULAR FUNCTIONAL RESERVE IN THE GROWTH ACCELERATED CHICK HEART: STAGES 21 TO 29. Pediatr Res 21 (Suppl 4), 188 (1987). https://doi.org/10.1203/00006450-198704010-00129
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DOI: https://doi.org/10.1203/00006450-198704010-00129