Objective: To develop and validate a new non-invasive method for the estimation of pulmonary arterial pressure (PAP) based on advanced signal processing of the second heart sound.
Design: Prospective comparative study.
Setting: Referral cardiology centre.
Patients: This method was first tested in 16 pigs with experimentally induced pulmonary hypertension and then in 23 patients undergoing pulmonary artery catheterisation.
Methods: The heart sounds were recorded at the surface of the thorax using a microphone connected to a personal computer. The splitting time interval between the aortic and the pulmonary components of the second heart sound was measured using a computer assisted spectral dechirping method and was normalised for heart rate.
Results: The systolic PAP varied between 14–73 mm Hg in pigs and between 20–70 mm Hg in patients. The normalised splitting interval was measurable in 97% of the recordings made in pigs and 91% of the recordings made in patients. There was a strong relation between the normalised splitting interval and the systolic PAP (pigs: r = 0.94, standard error of the estimate (SEE) = 5.3 mm Hg; patients: r = 0.84, SEE = 7.8 mm Hg) or the mean pulmonary pressure (pigs: r = 0.94, SEE = 4.1 mm Hg; patients: r = 0.85, SEE = 5.8 mm Hg).
Conclusions: This study shows that this new non-invasive method based on advanced signal processing of the second heart sound provides an accurate estimation of the PAP.
- heart sounds
- pulmonary hypertension
- signal processing
- A2, aortic component of the second heart sound
- HR, heart rate
- NSI, normalised splitting interval
- PAP, pulmonary arterial pressure
- P2, pulmonary component of the second heart sound
- S2, second heart sound
- SEE, standard error of the estimate
- SI, splitting interval
- SNR, signal to noise ratio
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