AN EXPERIMENTAL-MODEL FOR HEMODYNAMIC EVALUATION OF ARRHYTHMIAS IN RAT

Using the microsphere method cerebral blood flow (CBF) was determined in 60 rats during sinus rhythm and during ventricular pacing in order to quantitatively evaluate the effect of arrhythmias on cerebral circulation in combination with carotid artery disease in a new animal model. A heart catheter was inserted into the left ventricle via the right carotid artery in a retrograde fashion. An electrode was introduced through the lumen of the catheter for pacing of the left ventricle. CBF was measured during spontaneous sinus rhythm (n = 24) and 30-60 s after the onset of high-rate (660 or 840/min) ventricular pacing (n = 36). CBF demonstrated a slight interhemispheric difference during sinus rhythm due to carotid ligation. Pacing induced a decrease of mean arterial blood pressure (Pm) of varying degree. CBF dropped significantly during pacing in correlation to the reduction of Pm, when Pm was lower than 80-90 mm Hg. During follow-up Pm was easily adjustable by change of pacing rate. This model appears suitable for the hemodynamic evaluation of shortterm hypotensive episodes with rapid onset combined with carotid artery disease.