Right Heart Pressure Transients and Pulmonary Venous Pressure

Abstract

tricular (RV) ejection phase indices were limited in part because the complex shape and geometry of the right ventricle limited any reasonable calculation of volume and wall stress. Likewise, methods to assess the RV ejection fraction were in their infancy. By contrast, RV and pulmonary artery (PA) pressure measurements were relatively easy to obtain and it was thought that RV pressure transients and the isovolumic indices of contractility might be applied to the assessment of RV and perhaps even global cardiac contractility. This idea matured during deliberations about the independent function of the right ventricle and the fact that RV failure occurring secondary to LV failure was not easily explained on the basis of the relatively small pressure load imposed by elevated pulmonary venous pressures. Recognizing the distinct architectural and anatomic differences between the right and left ventricles, further discussions led to considerations of ventricular interaction and the possibility that the normal left ventricle directly assists the right ventricle in its pumping function while the dysfunctional left ventricle was limited in this regard. In the early 1970s, cardiologists exhibited a considerable interest in the relative merits of the isovolumic and ejection phase indices of left ventricular (LV) contractility. The isovolumic indices were derived from high-fidelity measurements of LV pressure prior to aortic valve opening; thus, LV pressure and the time derivative of pressure (dP/dt) were used to calculate ‘contractile element’ velocity during the early systole when ventricular volume was nearly constant. Because the pressure transients occurred prior to aortic valve opening, the isovolumic indices were considered to be independent of changes in aortic pressure and LV afterload. The ejection phase indices were derived from measurements of LV dimensions or volume during ejection; thus, dimension or volume strain (ejection fraction) and strain rates were determined. With the incorporation of pressure data, wall stresses were calculated, myocardial length-force-shortening relations were plotted, and afterload-ejection fraction assessed [1–4] . During this period, interest in the right ventricle was limited, mainly due to technical reasons. The right venReceived: April 28, 2016 Accepted after revision: May 9, 2016 Published online: June 10, 2016