McGoon ratio and Nakata index
(also pulmonary vein index and TNPAI)
The McGoon ratio
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The McGoon ratio is a pulmonary artery index designed for assessing certain cardiac conditions. It is calculated by dividing the sum of the diameters of the right pulmonary artery (measured where it crosses the lateral margin of the vertebral column) and the left pulmonary artery (measured just proximal to its upper lobe branch) by the diameter of the aorta at a point just above the diaphragm.
A McGoon ratio greater than 1.2 is associated with acceptable postoperative right ventricular systolic pressure. In contrast, a ratio below 0.8 is considered inadequate for a complete repair of pulmonary artery and ventricular septal defect (PA-VSD).
Diameter to Area calculator
Area = π(radius)² = π (diameter/2)² = (π/4) diameter² =0.785 x diameter²
Nakata index
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The Nakata index is calculated by taking the cross-sectional area of the left and right pulmonary arteries, measured in mm², and dividing it by the total body surface area (BSA).
The normal Nakata value is approximately 330 ± 30 mm²/BSA.
Pulmonary Vein Index (PVI)
PVI =
Sum of Pulmonary vein cross sectional area
Body surface area
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Aimed at assessing the predictive value of PVI for early outcomes in patients undergoing surgical treatment for TOF. PVI (mm²/m²)= (LPV − A + RPV − A) / Body Surface Area (BSA) (m²)
The area of the PVs (LPV-A, RPV-A) is measured 3 mm beyond the pulmonary venous ostium.
** LSPV: left superior pulmonary vein, LIPV: left inferior pulmonary vein, RSPV: right superior pulmonary vein, RIPV: right inferior pulmonary vein
Total Neo-pulmonary Artery Index [TNPAI]
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The Total Neo-pulmonary Artery Index (TNPAI) is a measurement used in cardiology, particularly for congenital heart conditions like pulmonary atresia with ventricular septal defect (PA-VSD).
TNPAI is computed by measuring the cross-sectional areas of the pulmonary arteries and the major aortopulmonary collateral arteries (MAPCAs), then dividing the result by body surface area (mm²/m²).
TNPAI = (Total PA Cross-Sectional Area + Total MAPCA Cross-Sectional Area) / BSA.
A Total Neo-pulmonary Artery Index (TNPAI) of 150 mm²/m² is used as a cut-off to determine the surgical strategy for certain congenital heart conditions, such as pulmonary atresia with ventricular septal defect and major aortopulmonary collateral arteries.
Result
Reference
Philip Urban, Roxana Mehran, Roisin Colleran, Dominick J Angiolillo, Robert A Byrne, Davide Capodanno, Thomas Cuisset, Donald Cutlip, Pedro Eerdmans, John Eikelboom, Andrew Farb, C Michael Gibson, John Gregson, Michael Haude, Stefan K James, Hyo-Soo Kim, Takeshi Kimura, Akihide Konishi, John Laschinger, Martin B Leon, P F Adrian Magee, Yoshiaki Mitsutake, Darren Mylotte, Stuart Pocock, Matthew J Price, Sunil V Rao, Ernest Spitzer, Norman Stockbridge, Marco Valgimigli, Olivier Varenne, Ute Windhoevel, Robert W Yeh, Mitchell W Krucoff, Marie-Claude Morice, Defining high bleeding risk in patients undergoing percutaneous coronary intervention: a consensus document from the Academic Research Consortium for High Bleeding Risk, European Heart Journal, Volume 40, Issue 31, 14 August 2019, Pages 2632–2653, https://doi.org/10.1093/eurheartj/ehz372