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The Effects of Medetomidine on Cardiac Contractility in Autonomically Blocked Dogs
Author(s) -
MORAIS HELIO S. AUTRAN DE,
MUIR III WILLIAM W.
Publication year - 1995
Publication title -
veterinary surgery
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.652
H-Index - 79
eISSN - 1532-950X
pISSN - 0161-3499
DOI - 10.1111/j.1532-950x.1995.tb01343.x
Subject(s) - medicine , medetomidine , contractility , cardiology , heart rate , blood pressure
The effects of medetomidine on load‐dependent and relatively load‐independent indices of left ventricular contractility and hemodynamics were studied in 8 chloralose‐anesthetized, autonomic‐blocked dogs. Left ventricular contractility was assessed by the maximum rate of increase in pressure (dP/dt max ), the slope of the end‐systolic pressure volume relationship (Ees), preload recruitable stroke work (PRSW), and dP/dt max ‐end‐diastolic volume relation (SdPV). Dogs received 5 or 10 μg/kg of medetomidine IV. The dP/dt max decreased significantly 30 minutes after both doses of medetomidine. The Ees did not change. Both SdPV and PRSW increased 5 minutes after both doses of medetomidine. Mean arterial pressure, left‐ventricular end‐diastolic and end‐systolic pressures, peripheral vascular resistance and effective arterial elastance increased 5 minutes after both doses of medetomidine. Stroke volume, cardiac output, and stroke work decreased 5 minutes after medetomidine administration. End‐diastolic volume did not change. End‐systolic volume increased but the difference was not significant. Our study suggests that medetomidine increases inotropy and vascular resistance in autonomic‐blocked dogs and that both ventricular and vascular responses to pharmacological manipulation must be considered for a complete assessment of the inotropic effects of a drug.