Biophysical factors and contractile function during coronary bolus perfusion: an experimental study in the isolated guinea pig heart.
OBJECTIVE
The purpose of this study was to evaluate the role of biophysical factors (viscosity, temperature, osmalality, perfusion pressure, and ionic washout) on cardiac contractility during coronary bolus perfusions.


METHODS
Guinea pig hearts were perfused in the osmolality mode at constant and high flow (30 mL/min) and were subjected to boluses (injected in 1-8 seconds) of purely nonionic media: mannitol and iohexol (in hyposmolal, isosmolal, and twice isosmolal forms) and iodixanol (in a hyposmolal form).


RESULTS
All contrast media elicited a dose-dependent increase in aortic pressure and contractile variables that was attenuated by an increased osmolality. Elevation of aortic pressure was followed by an increase in left ventricular systolic pressure and, with iodixamol and iohexol, a subsequent elevation of left ventricular end-diastolic pressure. Moderate hypothermic solutions (29 degrees C) did not alter the responses. The ionic washout profile was the same for the three substances, as were the individual washout profiles for sodium, potassium, chloride, magnesium, and calcium.


CONCLUSIONS
An increase in osmolality attenuates the increased contractility induced by a purely nonionic medium. A viscosity-induced rise in perfusion pressure may increase contractility. A moderate reduction in bolus temperature does not alter the contractile responses. The ionic washout profile is the same for the main cardioactive electrolytes.
Falck
G
G
University of Trondheim, Faculty of Medicine, Department of Pharmacology and Toxicology, Norway.
Olsen
H
H
Jynge
P
P
D000818:Animals; D001011:Aorta / Q000502:physiology; D003287:Contrast Media / Q000008:administration & dosage*; D017023:Coronary Angiography; D003326:Coronary Circulation; D006168:Guinea Pigs; D066298:In Vitro Techniques; D007267:Injections; D007472:Iohexol / Q000008:administration & dosage; D008297:Male; D008353:Mannitol / Q000008:administration & dosage; D009200:Myocardial Contraction; D009994:Osmolar Concentration; D010477:Perfusion; D011312:Pressure; D013696:Temperature; D014283:Triiodobenzoic Acids / Q000008:administration & dosage; D016277:Ventricular Function, Left; D017725:Ventricular Pressure; D014783:Viscosity
D003287:Contrast Media; D014283:Triiodobenzoic Acids; D008353:Mannitol; D007472:Iohexol; C044834:iodixanol