Use of Pressure-volume Conductance Catheters in Real-time Cardiovascular Experimentation

Background Most applications of pressure-volume conductance catheter measurements assess cardiovascular function at a single point in time after genetic, pharmacologic, infectious, nutritional, or toxicologic manipulation. Use of these catheters as a continuous monitor, however, is fraught with complexities and limitations. Methods Examples of the limitations and optimal use of conductance catheters as a continuous, real-time monitor of cardiovascular function are demonstrated during inotropic drug infusion in anesthetised rats. Results Inotropic drug infusion may alter ventricular dimensions causing relative movement of a well-positioned catheter, generating artifacts, including an abrupt pressure rise at end-systole that leads to over estimation of indices of contractility (max dP/dt) and loss of stroke volume signal. Simple rotation of the catheter, echocardiography-guided placement to the centre of the ventricle, or ventricular expansion through crystalloid infusion may correct for these artifacts. Fluid administration, however, alters left ventricular enddiastolic pressure and volume and therefore stroke volume, thereby obscuring continuous real-time haemodynamic measurements. Conclusions Pressure-volume artifacts during inotropic infusion are caused by physical contact of the catheter with endocardium. Repeated correction of catheter position may be required to use pressure volume catheters as a continuous real-time monitor during manipulations that alter ventricular dimensions, such as inotropic therapy.