Canadian Journal of Anesthesia, Vol 22, 436-448, Copyright © 1975 by Canadian Anesthesiologists' Society

A Comparison of Methods of Evaluating Myocardial Contractility

¹ Departments of Anaesthesia and Radiology, Memorial University, Newfoundland
² Departments of Anaesthesiax and Radiology, Memorial University, Newfoundland

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.

Note:

P.J. Tomlin. Present address: Department of Anaesthesia, University of Birmingham, Birmingham, England.

F. Duck. Present address: Department of Physics, Mayo Clinic, Rochester, Minnesota, U.S.A.