Acutely altered hemodynamics following venous obstruction in the early chick embryo

Abstract

SUMMARYIn the venous clip model specific cardiac malformations are induced in the chick embryo by obstructing the right lateral vitelline vein with a microclip. Clipping alters venous return and intracardiac laminar blood flow patterns,with secondary effects on the mechanical load of the embryonic myocardium. We investigated the instantaneous effects of clipping the right lateral vitelline vein on hemodynamics in the stage-17 chick embryo. 32 chick embryos HH 17 were subdivided into venous clipped (N=16) and matched control embryos(N=16). Dorsal aortic blood flow velocity was measured with a 20 MHz pulsed Doppler meter. A time series of eight successive measurements per embryo was made starting just before clipping and ending 5h after clipping. Heart rate, peak systolic velocity, time-averaged velocity, peak blood flow,mean blood flow, peak acceleration and stroke volume were determined. All hemodynamic parameters decreased acutely after venous clipping and only three out of seven parameters (heart rate, time-averaged velocity and mean blood flow) showed a recovery to baseline values during the 5h study period. We conclude that the experimental alteration of venous return has major acute effects on hemodynamics in the chick embryo. These effects may be responsible for the observed cardiac malformations after clipping.

Impact of Hypoxia on Early Chick Embryo Growth and Cardiovascular Function

“…response to hypoxia noted in fetal and adult vertebrates and is consistent with published data in the early embryo (10,13,14,18,24,28,35,36). In contrast to the mid-and lategestation fetus, the early embryo does not compensate for impaired CV function by adjusting HR.…”

“…In the current study, we tested the hypothesis that hypoxia alters both embryonic ventricular and vascular function and growth in the early embryo during the critical period of early morphogenesis when changes in ventricular and arterial function can produce permanent structural and functional alterations (12,13,24,(27)(28)(29). In response to chronic hypoxia from the onset of incubation, we noted decreased ventricular systolic function, increased arterial impedance, reduced arterial blood flow, and reduced embryo growth and survival.…”

Myocardin‐related transcription factor B is required for normal mouse vascular development and smooth muscle gene expression

“…However, defects in aortic arch patterning may also be a consequence of abnormal cardiovascular hemodynamics resulting from vitelline vein and liver congestion. For example, obstruction of the vitelline vein with a microclip can induce cardiac malformations in the chick embryo (Stekelenburg-de Vos et al, 2003). However, given the broad expression of MRTF-B and the results of our MRTF-B ⌬/⌬ mutant mice analysis, it is likely that MRTF-B has important roles in multiple tissues.…”

Systolic and Diastolic Ventricular Function Assessed by Pressure-Volume Loops in the Stage 21 Venous Clipped Chick Embryo

“…In a previous study using a 20 MHz Doppler velocity meter, we have demonstrated that the experimental alteration of venous return caused by venous clipping has major acute effects on hemodynamics in the HH stage 17 chick embryo (3,8). Peak systolic velocity, peak blood flow, and SV are all significantly decreased for up to 5 h after clipping.…”

“…The intricate relationship between hemodynamics and cardiac morphogenesis has been a major study topic in this model. The venous clip model is an intervention model for the chick embryo in which permanent obstruction of the right lateral vitelline vein temporarily reduces the mechanical load on the embryonic myocardium and induces a spectrum of outflow tract anomalies (3). This model was designed to obtain insight into the effects of altered venous return patterns on cardiac morphogenesis and malformations (4).…”