A minor experimental stenosis in porcine descending thoracic aorta affects the spectral content of pressure pulse wave.

Objective: To carry out research into the possible changes of the spectral content of pressure pulse wave after the creation of an experimentally induced stenosis in the pig descending thoracic aorta.
Methods: Eight healthy, normotensive Landrace pigs were subjected to thoracotomy under sterile conditions. At the upper segment of the descending thoracic aorta, a 5-mm-long circumferential symmetric constriction was imposed and stabilized; hence, a 15-20 mm Hg pressure gradient was established. Pressure tip catheters were used in order to monitor the pressure gradient. Blood flow disturbances were recorded through a bidirectional Doppler flow meter at pre- and poststenotic areas (A and B, respectively). Measurements were carried out before, 10 min after, and 90 days after the creation of the stenosis. The recorded waveforms were analyzed mathematically by using Fourier Transform, in order to determine their spectral component. Eight sham-operated pigs were used as controls.
Results: Fourier Transform analysis showed a significant increase (P < 0.05) of spectral content in A and B areas. Also, the "relative" harmonic amplitudes in nonstenotic subjects were higher than in stenotic animals (P < 0.05).
Conclusions: A minor experimental constriction located at the level of the descending thoracic aorta increased the spectral content of the pressure pulse wave, indicating that spectral analysis may detect slight flow disturbances before developing remarkable signs of an impaired circulation system.