Ventricular pressure-volume relations as the primary basis for evaluation of cardiac mechanics Return to Frank's diagram

Abstract

Considering ventricular function from the vantage point of the pressure-volume (P-V) diagram permits not only quantification of ventricular working capacity under normal and pathophysiological conditions but also promotes understanding of cardiac dynamics including prediction of the effects of mechanical and pharmacological interventions. Therefore it seems appropriate, at least intellectually, to classify all measured volume and pressure data into the scheme of the P-V diagram. The use of so-called contractility indices and also the restriction to the end-systolic P-V relation alone means deliberate renunciation of important information. In principle, Frank's original concept can be confirmed which, under afterloaded conditions, implies the existence of distinct end-systolic P-V curves each related to a particular end-diastolic volume. As an approximation, however, the assumption of one common end-systolic P-V relation seems tolerable. Based on Frank's diagram, a concept for assessment of ventricular and myocardial function is presented following a discussion of the determinants of the diastolic and end-systolic P-V relations, as well as the methodological difficulties and different notions with regard to the end-systolic P-V curve. The P-V area between the curves of systolic maxima and diastolic minima, up to a defined end-diastolic pressure, is recommended as a measure for quantitative evaluation of ventricular working capacity. Transformation into stress-length (sigma-l) relations is indispensable for assessment of myocardial function under the conditions of changed ventricular geometry. The normalized sigma-l area yields a measure for interindividual evaluation of myocardial working capacity. This concept of evaluation does not mean acknowledgement of the visco-elastic theory of muscle contraction nor of the Emax concept. The P-V and sigma-l relations must, however, be complemented by time related parameters in order to estimate ventricular and myocardial power capacity. After a long-lasting search through international literature for "contractility indices" of general applicability and significance it seems appropriate to return to Frank's diagram as the primary basis for evaluating cardiac mechanics.

Monitoring of cardiovascular physiology augmented by a patient-specific biomechanical model during general anesthesia. A proof of concept study

“…The simultaneous evaluation of the ventricular pressure and volume (PV loop) allows a functional interpretation of pathophysiological conditions, such as quantifying myocardial energetic expenditure or ventricular-arterial coupling [6] (see Fig 1). In some complex cases, the PV loop analysis can bring additional insight in to the current physiological state [7].…”

Assessing Left Ventricular Performance

“…15 Assessment of stress-length relations is indispensable for the assessment of myocardial function under conditions of changed ventricular geometry. 15 The findings of Osranek et al 10 …”

“…Heart rate increases with less change in end-systolic pressure (Figure). E max differs in the 2 conditions, 15 as does E a .…”

Frank Starling Mechanism on Alternating Pump Ventricular Models

“…On the other hand, they cannot describe indirect consequences which are based on biochemical processes or autoregulative mechanisms (namely the ventricular Frank Starling mechanism). 7,10,11 To overcome this limitation in part, an alternating pump ventricular simulator with an autoregulative Frank Starling mechanism was designed and tested. The device was then applied to rubber tubes of different compliance simulating the aorta to study the effects of changes in aortic compliance on ventricular work production.…”