The use of small animals in cardiovascular research has increased over recent years. This might be a limitation when evaluation of biventricular function is required. Although evaluation of left ventricular (LV) pressure and volume is already possible in small animals, concomitant evaluation of right ventricle function has been limited to large animals. The study describes a new model to assess pressures and dimensions of both ventricles simultaneously in the adult rat. Adult Wistar rats (n = 12), weighing 372 +/- 16 g, were anesthetized with pentobarbital (60 mg/kg, i.p.) and ventilated through a tracheostomy (60 cpm, 1 ml/100 g). Under a dissecting microscope (6x) the right jugular vein was catheterized. After sternotomy and pericardiotomy, three crystals were placed along the major cardiac transverse diameter: in the right subendocardium of the interventricular septum and on the epicardial surfaces of the RV and LV free walls. In addition, two high-fidelity catheters were introduced through the apex into the RV (2F, Millar) and LV (3F, Millar) cavities. This allowed the measurement of all parameters derived from pressure and dimension curves of the RV and LV, including pressure-dimension loops. This study describes, for the first time, a model that allows simultaneous evaluation of biventricular pressure and dimensions in an animal model as small as an adult rat. This model opens up new perspectives for the establishment of correlations between molecular biology and hemodynamic data in both ventricles, which is particularly important as more differences between the two ventricles are being found
