What does this research mean for the field?

The geometric mean of systolic and diastolic aortic pressures provides a highly reliable estimate of central mean aortic pressure in resting humans, establishing a direct mathematical link between the steady and pulsatile components of aortic pressure. Novelty: ClaimNovelty.METHODOLOGICAL. Consensus alignment: ConsensusAlignment.NEUTRAL.

July 29, 2005

Mean aortic pressure is the geometric mean of systolic and diastolic aortic pressure in resting humans

PICO estructurado

Does the geometric mean of systolic and diastolic aortic pressure provide a reliable estimate of mean aortic pressure compared to time-averaged MAP in resting humans?

Población

139 subjects, comprising controls (n=31) and subjects with various forms of cardiovascular diseases (n=108)

Intervención

Estimation of mean aortic pressure (MAP) using the geometric mean (square root of SAP x DAP) and three empirical formulas

Comparador

Time-averaged MAP measured via high-fidelity pressures recorded at rest at the aortic root level

Resultado

Accuracy and precision of MAP estimates compared to measured time-averaged MAP (mean bias and SD)surrogate

The geometric mean of systolic and diastolic aortic pressure provides a simple and reliable mathematical estimate of mean aortic pressure at the central level.

Resumen

The aim of our study was twofold: 1) to establish a mathematical link between mean aortic pressure (MAP) and systolic (SAP) and diastolic aortic pressures (DAP) by testing the hypothesis that either the geometric mean or the harmonic mean of SAP and DAP were reliable MAP estimates; and 2) to critically evaluate three empirical formulas recently proposed to estimate MAP. High-fidelity pressures were recorded at rest at the aortic root level in controls (n = 31) and in subjects with various forms of cardiovascular diseases (n = 108). The time-averaged MAP and the pulse pressure (PP = SAP - DAP) were calculated. The MAP ranged from 66 to 160 mmHg mean = 107.9 mmHg (SD 18.2). The geometric mean, i.e., the square root of the product of SAP and DAP, furnished a reliable estimate of MAP mean bias = 0.3 mmHg (SD 2.7). The harmonic mean was inaccurate. The following MAP formulas were also tested: DAP + 0.412 PP (Meaney E, Alva F, Meaney A, Alva J, and Webel R. Heart 84: 64, 2000), DAP + 0.33 PP + 5 mmHg Chemla D, Hébert JL, Aptecar E, Mazoit JX, Zamani K, Frank R, Fontaine G, Nitenberg A, and Lecarpentier Y. Clin Sci (Lond) 103: 7-13, 2002, and DAP + 0.33 + (heart rate x 0.0012) PP (Razminia M, Trivedi A, Molnar J, Elbzour M, Guerrero M, Salem Y, Ahmed A, Khosla S, Lubell DL. Catheter Cardiovasc Interv 63: 419-425, 2004). They all provided accurate and precise estimates of MAP mean bias = -0.2 (SD 2.9), -0.3 (SD 2.7), and 0.1 mmHg (SD 2.9), respectively. The implications of the geometric mean pressure strictly pertained to the central (not peripheral) level. It was demonstrated that the fractional systolic (SAP/MAP) and diastolic (DAP/MAP) pressures were reciprocal estimates of aortic pulsatility and that the SAP times DAP product matched the total peripheral resistance times cardiac power product. In conclusion, although the previously described thumb-rules applied, the "geometric MAP" appears more valuable as it established a simple mathematical link between the steady and pulsatile component of aortic pressure.

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