Comparison of ejection fraction and segmental circumferential fiber shortening velocity in the anesthetized and conscious canine.

A chronically and transseptally implanted left atrial catheter was utilized to perform repeated cineangiography in the conscious dog. The advantage of this preparation is that catheter placement does not require a thoracotomy. Left ventricular function was compared in the same pentobarbital-anesthetized and conscious dog. Anesthesia significantly depressed myocardial function as was demonstrated by a decrease in ejection fraction and segmental circumferential fiber shortening velocity (VCF) and an increase in end-diastolic volume. In addition, no difference in Vcf occurred between the base and the apex. Since anesthesia produced regional difference in the degree of depression of VCF, we conclude that anesthesia will produce patterns of ventricular contraction which are variable and unpredictable. Consequently, we recommend the use of the conscious dog and this preparation in order to evaluate myocardial function.