Cardiology Hemodynamics & Structural Heart Catheterization
Gorlin Aortic Valve Area (AVA) Catheterization Formula
Calculate Invasive Hemodynamic Stroke Volume (mL/beat), Mean Systolic Transvalvular Flow Rate (CO_L_min * 1000)/(HR * SEP), Richard & Sandra Gorlin’s Aortic Valve Area AVA = Flow / (44.3 * SQRT(Mean_Grad_mmHg)), and ACC/AHA Stenosis Severity.
Account for low-flow cardiac output alongside pressure gradient via the Gorlin Equation!
Evaluating aortic stenosis solely by transvalvular pressure gradient (Delta_P mmHg) misses Low-Flow, Low-Gradient Severe Aortic Stenosis when left ventricular systolic output falls—because fluid orifice gradient scales with flow SQUARED! Richard and Sandra Gorlin (1951, American Heart Journal) applied Torricelli’s hydraulic orifice law to invasive cardiac catheterization: first convert minute Cardiac Output (L/min) into Mean Systolic Transvalvular Flow (mL/s) = (CO_L_min * 1000) / (Heart_Rate_bpm * Systolic_Ejection_Period_sec), then divide by Gorlin’s aortic orifice constant 44.3 (or 37.7 for mitral diastolic filling!) times the square root of Mean Systolic Gradient: AVA_cm2 = Systolic_Flow_mL_s / (44.3 * SQRT(Mean_Grad_mmHg))!
Verify on a Cath-Lab Hemodynamic Run—Thermodilution_Cardiac_Output = 4.50 L/min (B2), Heart_Rate = 75 bpm (B3 -> Stroke Volume = 4,500 / 75 = 60.00 mL/beat in E2), Systolic_Ejection_Period SEP = 0.24 sec/beat (B4 -> 18.0 systolic sec/min, giving Systolic Flow = 4,500 / 18 = 250.00 mL/s in E3), and Mean_Transaortic_Gradient = 49 mmHg (B5 -> SQRT(49) = 7.0 exact!): Gorlin Aortic Valve Area AVA is 250 / (44.3 * 7) = 0.81 cm^2 (E4), classifying as "Severe Aortic Stenosis (AVA <= 1.0 cm2)" under ACC/AHA guidelines (E5)!
| Gorlin Cath-Lab Metric (CO=4.5 L/min, HR=75 bpm, SEP=0.24s, Mean Grad=49 mmHg) | Formula | Verified Output |
|---|---|---|
| Stroke Volume SV (mL/beat) | (Cardiac_Output_L_min * 1000) / HR | 60.00 mL/beat |
| Mean Systolic Flow Rate (mL/s) | (CO_L_min * 1000) / (HR * SEP_s) | 250.00 mL/s |
| Gorlin Aortic Valve Area (cm^2) | Flow_mL_s / (44.3 * SQRT(Grad_mmHg)) | 0.81 cm^2 (1.41 cm^2 @ 16 mmHg) |
| ACC / AHA Valve Stenosis Stage | <=1.0 Severe | <=1.5 Mod | >1.5 Mild | Severe Aortic Stenosis (AVA <= 1.0 cm2) |
Gorlin Invasive Aortic Valve Area (cm^2) Formula
Validate CO > 0, HR > 0, physiological ejection fraction of cycle 0 < HR * SEP < 60 sec/min, and Mean_Gradient > 0!
=LET(co_l, B2, hr_b, B3, sp_s, B4, gr_m, B5, IF(OR(co_l <= 0, hr_b <= 0, sp_s <= 0, hr_b * sp_s >= 60, gr_m <= 0), "Invalid Hemodynamic Trace", LET(fl_s, (co_l * 1000) / (hr_b * sp_s), ROUND(fl_s / (44.3 * SQRT(gr_m)), 2))))Moderate Stenosis Gradient Check (Set Mean Gradient = 16 mmHg)
Lower Mean_Transaortic_Gradient B5 to 16 mmHg (at identical 250 mL/s flow): SQRT(16) = 4, widening AVA E4 to 1.41 cm^2 ("Moderate Aortic Stenosis")!
=IF(ISTEXT(E4), E4, IF(E4 <= 1, "Severe Aortic Stenosis (AVA <= 1.0 cm2)", IF(E4 <= 1.5, "Moderate Aortic Stenosis", "Mild or Normal Valve Area")))Try the example
Use the original values or change them to test your understanding.