[Monitoring the right ventricle: methods and relevance]

For long, the right ventricle (RV) has been looked upon as a passive conduit of blood, which does not contribute to overall myocardial performance. While this is true under physiological conditions, it has been recognized only recently that an intact RV may be of crucial importance for the maintenance of cardiocirculatory stability under pathophysiological circumstances, e.g. in patients with increased pulmonary vascular resistance (PVR). Hence, several techniques have been developed to monitor RV function in these patients. With respect to the monitoring of RV preload, the validity of parameters based on pressure measurement (e.g. central venous pressure, RV end-diastolic pressure) is limited by the nonlinearity of the RV pressure-volume relationship, changes of RV compliance (e.g. ischemia, drugs), and changes of intrathoracic pressure. The measurement of RV end-diastolic volume (RVEDV) or size provides a more accurate estimation of true RV fiber preload and is currently performed using the fast-response thermodilution technique. The exact quantitation of RV afterload requires the continuous assessment of RV pressure, geometry and wall thickness, which is not possible in the clinical setting. Mean pulmonary artery pressure (PAP and PVR may roughly reflect actual RV afterload under physiological conditions. However, neither PAP nor PVR take into account changes of afterload due to changes of RV size. With respect to RV contractility, none of the techniques presently available for its measurement is both valid and suitable as a tool for clinical monitoring.