HR: Heart Rate.

LVOT: Left Ventricular Outflow Tract.

diam: Diameter

PLAX: Parasternal Long Axis.

VTI: Velocity-Time Integral

A4C: Apical 4 Chambers.

RVOT: Right Ventricular Outflow Tract.

PSAX: Parasternal Short Axis.

SV: Stroke Volume.

Q or QS: Systemic Cardiac Output.

BSA: Body Surface Area.

CI: Cardiac Index.

QP: Pulmonary Cardiac Output.

Electrocardiography

HR = 1500 / Small squares between R-R

QTc (Bazett) = QT / √RR

QTc (Fridericia) = QT / ∛RR (in seconds)

Echocardiography

LVOT area = π × (LVOT diameter/2)²

Systemic SV = LVOT area × LVOT VTI

QS = (HR × Systemic SV) / 1000

BSA (Mosteller) = √(Weight × Height) / 60

CI = QS / BSA

QP = (HR × SVp) / 1000

SVp = RVOT area × RVOT VTI

QP/QS Ratio = QP / QS

PAPs (Bernoulli) = (4 × V²) + RAP