Cardiovascular
Cardiovascular Physiology — Systems Overview
Core cardiovascular physiology: stroke volume, preload, afterload, cardiac output, and the Frank-Starling relationship as it applies to critically ill surgical patients.
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The primary goal of the cardiovascular system is to maintain perfusion — delivering oxygen and nutrients to all organ systems.
Key Definitions
Term • Definition • Stroke Volume (SV)Section
Key Definitions
Term • Definition • Stroke Volume (SV)| Term | Definition |
|---|---|
| Stroke Volume (SV) | Volume pumped from ventricle per contraction |
| Preload | Pressure on ventricular myocardium at end-diastole (EDV) |
| Afterload | Resistance the left ventricle must overcome to eject blood |
| Cardiac Output (CO) | CO = SV × HR |
Frank-Starling Relationship
Increased venous return → increased EDV → more myocyte stretch → stronger contraction → increased SV.Section
Frank-Starling Relationship
Increased venous return → increased EDV → more myocyte stretch → stronger contraction → increased SV.Increased venous return → increased EDV → more myocyte stretch → stronger contraction → increased SV.
This is the physiologic basis for fluid resuscitation in the underfilled patient.
Clinical Application
In critically ill or injured patients, understanding how to support:Section
Clinical Application
In critically ill or injured patients, understanding how to support:In critically ill or injured patients, understanding how to support:
- Preload — volume status optimization
- Afterload — vasodilators or vasopressors
- Contractility — inotropic support
- Heart rate — rate control or chronotropic support
... is essential to maintaining adequate perfusion.
- Adapted from SurgCritCare. org for structured display and mobile use. Verify against current institutional policies and attending guidance.*