Mechanical Preload Reduction: Harnessing a Cornerstone of Heart Failure Management to Improve Clinical Outcomes

Figures

• 

  Figure 1.. Factors influencing cardiac preload.

• 

  Figure 2.. Pressure-volume relationships illustrating the effect of preload. A: Pressure-volume loops showing that compared to steady state conditions (red), heart failure causes an increase in LV volume with reduced end-systolic elastance (straight line) and lower end-diastolic pressure-volume relationship (curved line). B: Pressure-volume loops showing that the effect of reducing total cardiac preload in heart failure (blue loops). Point a is maximal preload reduction. C: Starling curves illustrating steady state (black) and heart failure (blue) conditions and the effect of reducing cardiac preload. Point a is maximal preload reduction. EDP, end-diastolic pressure; LV, left ventricle; SV, stroke volume.

• 

  Figure 3.. Mechanical preload reduction technologies. A–C: Passive systems to occlude the inferior vena cava: Herrera balloon, Doraya, and Nephronyx, respectively. D: Active system to intermittently occlude the superior vena cava: Precardia system. IVC, inferior vena cava; MPR, mechanical preload reduction; SVC, superior vena cava.

• 

  Figure 4.. Hemodynamic effects of precardia therapy in heart failure. Bar graphs illustrating changes in hemodynamic parameters before and 3 hours after completing precardia therapy (*p < 0.01). MAP, mean arterial pressure; PA, pulmonary artery; PCWP, pulmonary capillary wedge pressure; RAP, right atrial pressure.

• 

  Figure 5.. Reducing preload augments unloading with a LV assist device. Top: Hemodynamic tracings of the left ventricle and aorta during the strain phase (preload reduction) in a patient with a durable LV assist device showing an increase in uncoupling of the ventricle from aorta. Bottom: Hemodynamic tracings of the left ventricle (purple) and aorta (white) after activation of an Impella CP device in a patient with severe right heart failure. Uncoupling of the ventricle from aorta is observed (green circles) due to loss of LV preload followed by activation of a right sided Impella RP pump to restore LV preload. AO = aortic; LV, left ventricular; PA, pulmonary artery; RA, right atrial.

• 

  Figure 6.. A) Representative pressure-volume loops illustrating reduced LV pressure and volume after activation of the preCARDIA superior vena cava occlusion system in the presence of an Impella CP pump activated, known as PrePella, at P3 or P8 levels of support. B: Pressure time tracings from the LV (black) and aorta (red) demonstrate reduced aortic pulse pressure and flattening of the tracing during systolic ejection and diastolic filling during PrePella activation. LV, left ventricular.