MBBS · Physiology

Cardiac output

Cardiac output measures blood pumped by one ventricle per unit time and is determined by heart rate and stroke volume. It changes with activity, preload, afterload and contractility.

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Cardiac output — learning map

Original conceptual SVG · scalable
LABELED RELATIONSHIP MAP · SCHEMATIC, NOT TO SCALEQuantify flowCO = HR × SVPreloadinitial ventricular fillingAfterloadopposition to ejectionContractility and regulationintrinsic pumpingCardiac outputKEY RELATIONSHIPS

Original schematic relationship map for this topic; relationships are organized for study, not intended as an anatomical depiction or a diagnostic algorithm.

Concept 01

Quantify flow

Cardiac output equals heart rate multiplied by stroke volume; stroke volume is end-diastolic minus end-systolic ventricular volume.

Concept 02

Preload

Venous return and ventricular compliance influence end-diastolic volume; preload is related to myocardial fiber stretch before contraction.

Concept 03

Afterload

Arterial pressure and ventricular wall stress contribute to the load against which the ventricle ejects.

Concept 04

Contractility and regulation

Autonomic signals, calcium handling, ischemia and cardiomyopathy can affect myocardial performance independently of preload.

Education / safety note: A normal heart rate does not guarantee adequate output; do not use a single number to assess circulatory stability.

Reference and next reading

Explore the original curriculum and publisher-hosted resources for full-depth reading; this note is an original schematic introduction, not an exhaustive chapter.

Official / publisher source: NMC official CBME Curriculum 2024 and current regulations index ↗Official / publisher source: NCBI Bookshelf ↗Official / publisher source: PubMed ↗