Right Ventricular Pressure Waveform Monitoring in Cardiac Surgery

Right ventricular (RV) dysfunction is mostly associated to a decrease in contractility, right ventricular pressure overload or right ventricular volume overload. RV dysfunction can occur in a number of clinical scenarios in the intensive care unit (ICU) and operating room (OR): pulmonary embolism, acute respiratory distress syndrome (ARDS), septic shock, RV infarction, and in pulmonary hypertensive patients undergoing cardiac surgery. Unfortunately, identifying which patients will develop RV dysfunction and then progress towards RV failure have proven difficult. One of the reasons for delaying the diagnosis of RV dysfunction could be the lack of uniform definition, especially in the perioperative period. Echocardiographic definitions of RV dysfunction have been described: RV fractional area change (RVFAC) \< 35 %, tricuspid annular plane systolic excursion (TAPSE) \< 16 mm, tissue Doppler S wave velocity \<10 cm/s, RV ejection fraction (RVEF) \<45% and RV dilation. However, echocardiographic indices alone are insufficient in describing RV function. The diagnosis of fulminant RV failure is more easily recognised as a combination of echocardiographic measures, compromised hemodynamic measures and clinical presentation. RV dysfunction is inevitably associated with absolute or relative pulmonary hypertension because of the anatomic and physiological connection between the RV and pulmonary vascular system. The gold standard for measuring pulmonary pressure is still the pulmonary artery catheter. However, RV output can initially be preserved despite of pulmonary hypertension. It is therefore mandatory that early, objective, continuous, easily obtainable and subclinical indices of RV dysfunction are found and validated to initiate early treatment of this disease.