Atrioventricular Valve Annulus Velocity and Acceleration during Global Hypoxia in Newborn Pigs – Assessment of Myocardial Function

Abstract

Background: Global hypoxia may affect regions of the neonatal heart during systole and diastole differently. Objective: In the first study, the aim was to assess longitudinal myocardial function in newborn pigs during global hypoxia and recovery. In the second study, invasive hemodynamic data were evaluated and compared with tissue velocities and acceleration. Methods: Myocardial Doppler measurements of velocity and acceleration in the atrioventricular valve annuli during global hypoxia were made. Results: In the first experiment, systolic velocity (S), early diastolic velocity (E’) and peak systolic acceleration (pSac) decreased during hypoxia. S, pSac and E’_mva (mitral valve annulus) recovered after reoxygenation, while E’_septal and E’_tva (tricuspid valve annulus) did not. Isovolumic acceleration (IVA) did not reflect systolic dysfunction. In the second experiment, S_mva and pSac_mva declined during hypoxia similarly to maximum dP/dT. E’_mva and E’_tva were correlated with τ and both changed parallel to minimum dP/dT. In the TVA maximum dP/dT and pSac_tva did not change, while S_tva declined. By correcting for heart rate the pattern of alteration in S and pSac became comparable to the changes in E’. Conclusion: Tissue Doppler velocity in systole, diastole and acceleration during rapid ejection reflect hemodynamic changes in the neonatal myocardium during global hypoxia and recovery. S and pSac reflect systolic function, while E’ correlates with τ and mirrors diastolic function.