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Aortic pressure wave reconstruction during exercise is improved by adaptive filtering: a pilot study.

Stok WJ, Westerhof BE, Guelen I, Karemaker JM - Med Biol Eng Comput (2011)

Bottom Line: The optimal resonance frequency was predicted from regression formulas using variables derived from the individual's peripheral pressure pulse, including a pulse contour estimation of cardiac output (pcCO).Using a genTF and without calibration, the error in estimated aortic pulse pressure was -7.5 ± 6.4 mmHg, which was reduced to 0.2 ± 5.7 mmHg with the indTFs using pcCO for prediction.Calibration resulted in less scatter at the cost of a small bias (2.7 mmHg).

View Article: PubMed Central - PubMed

Affiliation: Heart Failure Research Centre, Academic Medical Center, University of Amsterdam, Room M01-215, Meibergdreef 9, NL-1105 AZ, Amsterdam, The Netherlands. w.stok@amc.uva.nl

ABSTRACT
Reconstruction of central aortic pressure from a peripheral measurement by a generalized transfer function (genTF) works well at rest and mild exercise at lower heart rates, but becomes less accurate during heavy exercise. Particularly, systolic and pulse pressure estimations deteriorate, thereby underestimating central pressure. We tested individualization of the TF (indTF) by adapting its resonance frequency at the various levels of exercise. In seven males (age 44-57) with coronary artery disease, central and peripheral pressures were measured simultaneously. The optimal resonance frequency was predicted from regression formulas using variables derived from the individual's peripheral pressure pulse, including a pulse contour estimation of cardiac output (pcCO). In addition, reconstructed pressures were calibrated to central mean and diastolic pressure at each exercise level. Using a genTF and without calibration, the error in estimated aortic pulse pressure was -7.5 ± 6.4 mmHg, which was reduced to 0.2 ± 5.7 mmHg with the indTFs using pcCO for prediction. Calibration resulted in less scatter at the cost of a small bias (2.7 mmHg). In exercise, the indTFs predict systolic and pulse pressure better than the genTF. This pilot study shows that it is possible to individualize the peripheral to aortic pressure transfer function, thereby improving accuracy in central blood pressure assessment during exercise.

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Reconstruction (thin lines) of aorta pressure waves (bold lines) from finger pressure during rest and at maximum workload in three subjects. From left to right: genTF in rest and at maximal workload and with individual TFs (indTF) using finger pcCO in rest and at maximal workload. Subject 1 and 5 with relatively high maximum HR, subject 6 with low maximum HR
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Fig4: Reconstruction (thin lines) of aorta pressure waves (bold lines) from finger pressure during rest and at maximum workload in three subjects. From left to right: genTF in rest and at maximal workload and with individual TFs (indTF) using finger pcCO in rest and at maximal workload. Subject 1 and 5 with relatively high maximum HR, subject 6 with low maximum HR

Mentions: Short traces of aortic pressure and reconstructed aortic pressure waves from three subjects are presented in Fig. 4, showing the wave reconstruction results using the genTF and the indTFs (Formula 1, pcCO) during rest and during each subject’s maximal workload. Maximum HR was relatively high in subject 1 and 5, and low in subject 6.Fig. 4


Aortic pressure wave reconstruction during exercise is improved by adaptive filtering: a pilot study.

Stok WJ, Westerhof BE, Guelen I, Karemaker JM - Med Biol Eng Comput (2011)

Reconstruction (thin lines) of aorta pressure waves (bold lines) from finger pressure during rest and at maximum workload in three subjects. From left to right: genTF in rest and at maximal workload and with individual TFs (indTF) using finger pcCO in rest and at maximal workload. Subject 1 and 5 with relatively high maximum HR, subject 6 with low maximum HR
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3139898&req=5

Fig4: Reconstruction (thin lines) of aorta pressure waves (bold lines) from finger pressure during rest and at maximum workload in three subjects. From left to right: genTF in rest and at maximal workload and with individual TFs (indTF) using finger pcCO in rest and at maximal workload. Subject 1 and 5 with relatively high maximum HR, subject 6 with low maximum HR
Mentions: Short traces of aortic pressure and reconstructed aortic pressure waves from three subjects are presented in Fig. 4, showing the wave reconstruction results using the genTF and the indTFs (Formula 1, pcCO) during rest and during each subject’s maximal workload. Maximum HR was relatively high in subject 1 and 5, and low in subject 6.Fig. 4

Bottom Line: The optimal resonance frequency was predicted from regression formulas using variables derived from the individual's peripheral pressure pulse, including a pulse contour estimation of cardiac output (pcCO).Using a genTF and without calibration, the error in estimated aortic pulse pressure was -7.5 ± 6.4 mmHg, which was reduced to 0.2 ± 5.7 mmHg with the indTFs using pcCO for prediction.Calibration resulted in less scatter at the cost of a small bias (2.7 mmHg).

View Article: PubMed Central - PubMed

Affiliation: Heart Failure Research Centre, Academic Medical Center, University of Amsterdam, Room M01-215, Meibergdreef 9, NL-1105 AZ, Amsterdam, The Netherlands. w.stok@amc.uva.nl

ABSTRACT
Reconstruction of central aortic pressure from a peripheral measurement by a generalized transfer function (genTF) works well at rest and mild exercise at lower heart rates, but becomes less accurate during heavy exercise. Particularly, systolic and pulse pressure estimations deteriorate, thereby underestimating central pressure. We tested individualization of the TF (indTF) by adapting its resonance frequency at the various levels of exercise. In seven males (age 44-57) with coronary artery disease, central and peripheral pressures were measured simultaneously. The optimal resonance frequency was predicted from regression formulas using variables derived from the individual's peripheral pressure pulse, including a pulse contour estimation of cardiac output (pcCO). In addition, reconstructed pressures were calibrated to central mean and diastolic pressure at each exercise level. Using a genTF and without calibration, the error in estimated aortic pulse pressure was -7.5 ± 6.4 mmHg, which was reduced to 0.2 ± 5.7 mmHg with the indTFs using pcCO for prediction. Calibration resulted in less scatter at the cost of a small bias (2.7 mmHg). In exercise, the indTFs predict systolic and pulse pressure better than the genTF. This pilot study shows that it is possible to individualize the peripheral to aortic pressure transfer function, thereby improving accuracy in central blood pressure assessment during exercise.

Show MeSH
Related in: MedlinePlus