Assessment of diastolic function: suggested methods and future considerations.

RECENT STUDIES in diseased hearts have demon- strated that diastolic dysfunction may precede abnor- malities in systolic ventricular performance.There- fore, it is important to critically review methods currently being used in the assessment of diastolic function.Many review articles and symposia that express dif- fering points of view have been published recently.'-5Several of the controversies stem from a misunder- standing of basic principles of physics and mathemat- ics, the use of inappropriate analyses, and the desire to develop simple indexes of diastolic function.The em- phasis here will therefore be on the development of relationships between pertinent physiologic parameters, the applications of various mathematic models, and suggestions of topics requiring further study.In particular, attention will be focused on methods for the assessment of chamber stiffness, myocardial stiffness, and the time constant of relaxation since these are important factors involved during shifts in the pres- sure-volume relationship after drug intervention or pacing-induced angina. Methods and illustrative examplesAssessment of chamber stiffness.Chamber stiffness is generally defined as a change in pressure relative to a change in volume (i.e., dP/dV) of a hollow elastic structure such as the left or right ventricle.Its reciprocal (dV/dP) is termed chamber compliance.Exponentiality of the diastolic pressure-volume re- lationship has been demonstrated in animal studies and therefore the relationship P = Aekv (where P is pres- sure and A and k are curve-fitting parameters) has often been invoked.Since the resulting chamber stiffness-pressure relationship is linear (dP/dV = kAekv = kP), the slope k is being used as an index of cham-