Stroke Volume Calculator - SV, SVI, and LVOT Branches

A stroke volume calculator turns the volume of blood the left ventricle ejects per beat into a single mL/beat number, so the same bedside worksheet, echo report, and Swan-Ganz tracing can be compared. The page covers three clinical branches (EDV minus ESV, CO/HR, and LVOT Doppler), the 60 to 100 mL/beat resting band, the SVI, and the limits of any single mL/beat value.

• • Bedside haemodynamic worksheet check: Drop in a measured CO and HR, or an EDV/ESV read from echo, and read the same mL/beat result.
• • Echo and cath lab readouts: Use the LVOT Doppler branch with a measured LVOT diameter and VTI to return the same mL/beat value the ASE worksheet quotes.
• • Endurance and exercise cardiology: Use the CO/HR branch with a measured CO and a low resting heart rate to confirm the larger SV of a trained heart at rest.
• • Sizing for downstream calculations: Use the SVI in mL/beat/m^2 for a cardiac index, a target CO for sepsis resuscitation, or a BSA-normalised comparison.

When the bedside worksheet already has a measured cardiac output and the next step is the L/min value, Cardiac Output Calculator returns the same L/min from HR times SV, LVOT Doppler, the Fick principle, or a direct entry.

The form works in three short steps. It reads the inputs from the branch you selected, computes the SV in mL/beat, and divides by the Haycock body surface area to also return an SVI in mL/beat/m^2 with a severity band.

• EDV, ESV: LV end-diastolic and end-systolic volumes in mL from the same echo method.
• CO, HR: Cardiac output in L/min and heart rate in bpm. The CO/HR branch uses these directly.
• LVOT_diameter, LVOT_VTI: LVOT inner-edge diameter in cm and velocity-time integral in cm from a Doppler read. The LVOT branch multiplies area by VTI.
• BSA: Body surface area in m^2 from Haycock, the divisor for the SVI.

All three branches converge on the same mL/beat number, but the precision of the input matters. A 0.2 cm error in the LVOT diameter compounds into roughly a 20 percent change in the LVOT result, and a 5 bpm error in HR on the CO/HR branch moves the result by around 7 percent.

According to StatPearls - Physiology, Cardiac Output, the normal resting adult stroke volume is 60 to 100 mL per beat, and the SVI is 35 to 65 mL per beat per square metre of body surface area.

When the same size-normalisation step is needed on the L/min side, Cardiac Index returns the cardiac index in L/min/m^2 from the same SV that drives this calculator's SVI.

Four ideas carry most of the clinical meaning behind an SV read.

All three branches feed the same mL/beat result, but the inputs come from different parts of the bedside and echo workflow. Picking the right branch is what makes the result match the worksheet the rest of the team is reading. When the Haycock BSA step needs Mosteller or DuBois for an adult dosing comparison, Body Surface Area Calculator returns BSA in m^2 from height and weight.

Treat the calculator as a structured readout of one of three bedside or echo inputs. The branch selector picks the arithmetic, and the result panel maps to a clinical interpretation.

1. 1 Pick the branch: EDV/ESV for an echo read, CO/HR for a bedside worksheet, LVOT for a Doppler worksheet.
2. 2 Enter the inputs: EDV and ESV in mL, CO in L/min, HR in bpm, LVOT diameter in cm, LVOT VTI in cm.
3. 3 Add height and weight for the SVI: Used by the Haycock BSA formula to size-normalise the result.
4. 4 Read the result and severity band: Compare the mL/beat value to the 60 to 100 mL/beat band. The severity tag labels low, normal, or high.
5. 5 Use SVI across body sizes: A 70 mL/beat read on a 1.04 m^2 child and on a 2.10 m^2 adult are not the same picture. SVI normalises for that.

A practical use: a 60-year-old arrives in the ED with a CO of 3.0 L/min on thermodilution and a heart rate of 95 bpm. SV works out to 3.0 x 1000 / 95 = 31.6 mL/beat, well below the resting band, so the next step is hypovolaemia, LV dysfunction, or severe regurgitation.

When the heart-rate input on the CO/HR or LVOT branch is taken from a strip and the team needs a second check, ECG Heart Rate Calculator returns the bpm from an ECG that pairs with the same worksheet the SV read comes from.

A bedside calculator turns three bedside inputs into a single mL/beat answer that is easy to chart.

• • Three branches, one number: EDV/ESV, CO/HR, and LVOT Doppler all converge on the same mL/beat value, so the result matches the worksheet the rest of the team is reading.
• • Built-in adult resting band: The 60 to 100 mL/beat StatPearls resting band is shown next to the result, so a low or high read is visible at a glance.
• • Size-normalised SVI alongside the raw mL/beat: Returns a Haycock BSA and a SVI in mL/beat/m^2 so patients of different sizes can be compared on the same scale.
• • Ejection fraction on the EDV/ESV branch: Surfaces the EF as a percentage, so the same mL/beat value is not mistaken for a normal ventricle when the EF is reduced.
• • Works on echo, bedside, and ICU worksheets: The same input format covers a Teichholz read, a thermodilution CO, and a Doppler continuity equation.

Most published reference cards only give the CO/HR branch. A calculator that also covers the EDV/ESV branch and the LVOT continuity equation is more useful for the mix of inputs seen on an echo report, a bedside worksheet, and a Doppler read.

Several variables change the result, and the calculator surfaces the most important ones in the result panel and the inputs.

• • The calculator is a bedside estimate, not a measurement. Echo volumes carry a 5 to 15 percent geometric error, and the LVOT diameter is squared inside the cross-sectional area.
• • A normal SV with a reduced EF is still a sick ventricle. The calculator surfaces the EF so the result is read with the geometry, not as a stand-alone rule-out.
• • Severe valvular regurgitation and shunts can make the LVOT Doppler and EDV/ESV branches disagree. The CO/HR branch is the most useful when the team has both an echo and a thermodilution CO.

The calculator is meant to be read with the clinical picture, imaging, and trend over time. A single mL/beat value does not diagnose hypovolaemia, sepsis, or heart failure.

According to Teichholz et al. - Echocardiographic Volume Determinations (Am J Cardiol, 1976), the SV from an echocardiographic volume determination is the difference between the LV end-diastolic and end-systolic volumes, with both volumes read from the same geometric model.

According to ASE/EACVI Chamber Quantification Recommendations (J Am Soc Echocardiogr, 2015), the Doppler SV is the product of the LVOT cross-sectional area and the LVOT velocity-time integral, and the resulting value is the same SV the continuity equation returns.

When the afterload question is the next thing on the worksheet and a fresh mean arterial pressure is needed, Blood Pressure Calculator returns MAP and pulse pressure from systolic and diastolic so the same mL/beat value can be read against the same afterload number.