Summary
An investigation was carried out in dogs to determine how the acceleration of blood in the aorta (dV/dt), as a new index of myocardial contractility compared with existing indices and how they correlated with each other. It was found that the indices derived from velocity and flow of blood, dV/dt max and dQ/dt max, and from intraventricular pressure, dP/dt max, correlate well with each other but there is less agreement between them and the reciprocal of the Pre-Ejection Period, 1/PEP. The ratio dP/dt max ÷ I.P. correlated well with dQ/dt max ÷ I.Q. and dQ/dt max ÷ Q. max but not so well with dV/dt max ÷ I.V. (instantaneous velocity) or dV/dt max ÷ V. max and the ratios dQ/dt ÷ I.Q. and dQ/dt ÷ Q max as well as 1/PEP. In view of the lack of agreement of quantitative definition of myocardial contractility, the ratio dV/dt ÷ V. max would have several practical advantages as an indicator of the inotropic state of the heart; these are that the probe used to establish descending aortic blood velocity does not require calibration, and the signal can be obtained by a relatively non-invasive technique that is suitable for patient care and yet agrees with other established indices of myocardial contractility.
Résumé
Ce travail, effectué chez le chien, avait pour but de comparer entre eux différents indices de contractilité myocardique et, en particulier d’étudier leurs corrélations entre eux et un nouvel index, à savoir, le dV/dt (accélération du flot sanguin aortique). Nos résultats ont montré une bonne corrélation entre les indices dérivés de la vélocité et du débit sanguin (dV/dt max et dQ/dt max) et le dP/dt max dérivé de la pression intraventriculaire; il y avait cependant moins bonne corrélation entre eux et la réciproque de l’intervalle pré-éjection (Pre-Ejection period) - 1/PEP.
Le rapport dQ/dt max ÷ I.P. montrait une bonne corrélation avec dQ/dt max ÷ Q, mais ce n’était pas le cas si on le comparait à dV/dt max ÷ I.V. (vélocité instantanée), à dV/dt max ÷ V. max, à dQ/dt ÷ I.Q., à dQ/dt max ÷ Q max et à 1/PEP.
Considérant qu’il n’y a pas unanimité sur la définition quantitative de la contractilité myocardique, le rapport dV/dt ÷ V max nous semble présenter plusieurs avantages pratiques comme indice de l’état inotropique du coeur, à savoir que (1) le cathéter introduit dans l’œsophage pour délimiter la vélocité du flot sanguin aortique au moyen d’ultrasons ne requiert pas de calibration, (2) que cette technique est relativement non-invasive et (3) qu’il y a bonne corrélation entre elle et les index établis de contractilité myocardique.
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Tomlin, P.J., Duck, F., McNulty, M. et al. A comparison of methods of evaluating myocardial contractility. Canad. Anaesth. Soc. J. 22, 436–448 (1975). https://doi.org/10.1007/BF03004858
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DOI: https://doi.org/10.1007/BF03004858