Preload

• Preload is defined as the amount of myocardial (sarcomere or myocyte) stretch that occurs at the end of ventricular filling during diastole.
• It is closely related to the end-diastolic volume, yet clinically is often estimated as the end-diastolic pressure.

RV Preload

• Because of its thin-walled structure and compliant nature, the RV is able to accommodate significant increases in acute preload.
• However, excessive acute RV preload can lead to RV failure via leftward septal shift and increased adverse ventricular interdependence, particularly in the setting of reduced RV contractile function or elevated RV afterload.
• Chronic elevation on RV preload leads to progressive RV dilation and worsening RV function over time including impairments in RV contractile reserve.
• Excessive RV preload leads to venous congestion of multiple organ systems, including the kidneys.
  • Renal venous congestion is a key driver of the cardiorenal syndrome, as excessive renal venous pressure initiates a cycle of sodium and fluid retention which may lead to further increases in both right atrial and pulmonary venous pressures.