End-diastolic pressure-volume relationship

Diuretics and angiotensin-converting enzyme (ACE) inhibitors decrease cardiac output, dLYP/d, and end-diastolic pressure-volume relationships in normals but change these parameters, little, in heart failure patients. Studies in normals depend principally on decreasing preload, and effects on patients with diseases that increase preload would be/may be ntissed. 

JANICKI If you look at Shirato s data and if you look at the end diastolic point, they, more or less, fall on the exponential curve, even though the curves he gives, which are from the end of rapid filling to end diastole, are shifted. But they still end up on what looks like the end diastolic pressure-volume relationship. 

Figure 1. Schematic explanation of coupling the left ventricular contraction with the systemic arterial tree. In the middle left panels, left ventricular contraction is represented by its end-systolic pressure-volume relationship. Given a particular end diastolic volume (EDV), this relationship can be converted into ventricular end-systolic pressure P s) stroke volume (5Vj relationship, which is shown by the rectilinear curve coursing from the lower left to upper right corner in the graph at the bottom. In the right middle panel, the aortic input impedance property is represented by a rectilinear arterial end-systolic pressure fF, )-stroke volume SV) relationship curve (Eq. (5)). See the text for the explanation of this representation. This arterial Pes-SV relationship is transcribed in the bottom panel in superposition with the ventricular Pe -SV relationship. The intersection of the two Pes-SV relationship curves indicates the end-systolic pressure and stroke volume which should result from coupling a left ventricle with the given EDV and the slope parameter with a systemic arterial tree with the slope parameter...

FIGURE 8.2 Time-varying ventricular elastance curves measured using the definition in Equation 8.3. Measured elastance curves are distinctive in shape. (Adapted from Suga, H. and Sagawa, K. 1974. Instantaneous pressure-volume relationship under various end-diastolic volume. Circ Res. 35 117-126.)... 

Suga, H. and Sagawa, K. 1974. Instantaneous pressure-volume relationship under various end-diastolic volume. Circ. Res. 35 117-126. 

Here, PVR (pressure-volume relationship) is the active P-V curve, and PVRgs and PVRd are the end systolic and diastolic P-V curves, respectively. Using this approach, the PVRgs curve would be parameterized in terms of the inotropic state of the myocardium, and fmax would be a function of inotropic state and heart rate. 

The development of practical methods for the assessment of myocardial contractility continues and while the ESP-ESV concept provides one approach for quantitating changes in the contractile state, it requires further modification in order that it may be employed for patient to patient comparison. The preliminary studies described here on the basis of the developed stress concept shows some promise, however, further studies are required to examine the relationships between peak systolic pressure and end diastolic volume in order to explore an alternative definition for developed stress. 

Over the past decade, we (Sagawa, 1978) have measured the ventricular pressure (P)-volume (V) relationship in an isolated and blood perfused canine heart preparation and came to consider that the ventricular end-systolic P-V relationship (ESPVR) is (a) linear as opposed to the highly nonlinear P-V relationship of the frog s ventricle reported by Otto Frank a century ago, (b) rather insensitive to the preload and afterload and (c) changes its slope (E, ) sensitively with inotropic interventions without a significant shift in the volume intercept (Vq). This is to say that our model of the ventricle merely consists of a linear volume elastance E which varies with each heart beat from a smaller end-diastolic value to a larger... 

Equation (2) states that, given an end-diastolic volume 5V is inversely proportional to (the line coursing from the lower left to upper right corner of the bottom panel of Figure 1). This rectilinear relation is denoted the ventricular end-systolic pressure-stroke volume relationship (VPSVR) . 

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