Ventricular function curve

Ventricular function curves in the normal heart, in congestive heart failure (CHF), and in CHF treated with digitalis. 

Ventricular function curve The graph that relates cardiac output, stroke volume, etc, to filling pressure or end-diastolic fiber length also known as the Prank-Starling curve... 

Sarnoff, S.J. and Berglund, E. Ventricular function 1. Starhng s law of the heart studied by means of simultaneous right and left ventricular function curves in the dog. Circulation, IX, 706-719,1954. 

Hypertension (blood pressure >140/90 mmHg) may be caused by an elevation in cardiac output or excessive vasoconstriction. Diuretics are used in these patients to reduce cardiac output. Assume that the hearts of these individuals are operating on the ascending portion of the cardiac function curve. As the plasma volume is reduced in response to treatment with diuretic drugs, venous return and preload are reduced, as are ventricular filling and stroke volume, and cardiac output, thus bringing blood pressure back within the normal range. 

Ventricular function (Frank-Starling) curves, which plot any function of preload versus any function of cardiac work, reveal that compensatory mechanisms in untreated heart failure (mostly deleterious) may shift such curves upward and to the left. Compensation in heart failure is offset by specific drugs that can ... 

Figure 13-2. Ventricular function (Frank-Starling) curves. The abscissa can be any measure of preload—fiber length, filling pressure, pulmonary capillary wedge pressure, etc. The ordinate is a measure of useful external cardiac work—stroke volume, cardiac output, etc. In congestive heart failure, output is reduced at all fiber lengths and the heart expands because ejection fraction is decreased. As a result, the heart moves from point A to point B. Compensatory sympathetic discharge or effective treatment allows the heart to eject more blood, and the heart moves to point C on the middle curve.

FIGURE 8.7 Ventricular elastance curves computed using the new analytical function of Equation 8.10. Elastance curves computed in this way are representative of the ventricle s contractile state. 

These isovolumic pressure curves were then described by the following equation. Ventricular pressure pv is a function of time t and ventricular volume Vy according to... 

The functionality of the valve has been tested with equipment which has been made in our laboratory. Pulsatile flow tests on a mock circulatory system, flow patterns, measurements of steady retrograde flow and pressure drop across the valve, in vivo tests have been carried out. By the pulsatile flow tests, the shapes of curves referring to ventricular and aortic pressure and to flow rate, similar to that shown by other kinds of valves, have been observed. 

SCD-HeFT, a prospective NIH-sponsored, multicenter, randomized primary prevention trial enrolling high-risk, well treated. New Yoric Heart Association Functional Class II and HI heart failure patients tested the hypothesis that vamio-darone or ICD implant, compared to a placebo pill would improve survival. Patients with left ventricular ejection fractions < 0.35 were enrolled, and randomized to a placebo piU, amiodarone, or an ICD. Patients (n = 2,521) were followed for a median of 45.5 months. ICDs deaeased risk of death compared with placebo (hazard ratio, 0.77 p = 0.007). The curves deviated at 18 months. Amiodarone had a similar mortality outcome compared with placebo (hazard ratio, 1.06 p = 0.53) (Fig. 14.3). The absolute risk reduction at 5 years was 7.2%. 

One of the perils of any modeling analysis is the failure to obtain the input function to the system under study. For both single photon and PET imaging of the heart, the left ventricular cavity blood pool concentration-time curve gives the appropriate information when it is convoluted with the vascular transport function between the ventricular cavity and the coronary artery inflow. (Low order differential operators can be used to describe purely intravascular dispersive transport.)... 

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