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The maximum derivatives of left ventricular pressure and transverse internal diameter as indices of the inotropic state of the left ventricle in conscious dogs
Author(s) -
Barnes G. E.,
Bishop V. S.,
Horwitz L. D.,
Kaspar R. L.
Publication year - 1973
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.1973.sp010405
Subject(s) - preload , afterload , ventricle , heart rate , inotrope , medicine , cardiology , phenylephrine , ventricular pressure , blood pressure , hemodynamics
1. In normal, conscious dogs, I.V. infusion of isoprenaline caused inases in heart rate and the maximal derivatives of left ventricular pressure (d P /d t max) and left ventricular internal diameter (d D /d t max). The changes in both derivatives were linearly related to the increase in heart rate. 2. Increments in heart rate produced by right atrial pacing caused only minimally significant increases in both d P /d t max and d D /d t max at heart rates of 180 beats/min. Increases in heart rate, with end diastolic diameter maintained constant, resulted in small but significant increases in d P /d t max and no significant increase in d D /d t max. 3. Increasing preload by volume infusion had little effect on either derivative, while increasing afterload by phenylephrine administration produced a small but significant increase in d P /d t max and no change in d D /d t max. 4. Both d P /d t max and d D /d t max are equally reliable as indices of the inotropic state of the myocardium and are minimally influenced by changes in preload, afterload or heart rate.