Perioperative Hemodynamic and Microcirculatory Physiological Study During TAVI

Measurement of arterial stiffness using a non-invasive pressure transducer placed on the skin of the wrist, which records the pulse wave at the level of the radial artery in order to analyze the characteristics of the arterial wall. The parameters of interest are the arterial stiffness of large- and small-caliber arteries (ml/mmHg).

Measurement of plasma Vascular Endothelium Growth Factor levels by ELISA

Measurement of skin surface temperature gradient, defined as the difference in temperature between the skin surface of the forearm and that of the fingertip (forearm-to-fingertip)

Measurement of endothelial function by a vaso-occlusion test performed by inflating a cuff on the arm to occlude arterial flow for 3 min. Reactive hyperemia on deflation of the cuff is measured by photoplethysmography placed on the index finger, and tissue oxygen saturation (StO2) by near-infrared spectroscopy (NIRS). The amplitude of the reperfusion flow corresponding to the peak of the perfusion index (ΔPI Peak) and the time to reach this peak (time to peak) are the parameters recorded by photoplethysmography. Tissue resaturation rate (rStO2) is the parameter recorded by NIRS.

The diameter of the left ventricular outflow tract is measured in the tele systolic parasternal long-axis view. The pulsed Doppler flow profile is acquired at the level of the left ventricular chamber in the apical five-chamber view. The time-velocity integral of the aortic flow is then calculated. Left ventricular end-diastolic and end-systolic volumes are also measured using Simpson's method in the 4-cavity monoplane view. Measurements of vena cava diameter and respiratory variability of vena cava diameter provide an estimate of right atrial pressure. These measurements estimate cardiac output and systemic vascular resistance.

The perfusion index (PI) is derived from the signal and represents the ratio between the absorbance or reflectance of pulsatile and non-pulsatile light of the photoplethysmography signal. PI is measured non-invasively using a photoplethysmographic sensor placed on the earlobe or finger.

TAVI is a treatment for aortic valve stenosis. A new valve is inserted with minimally invasive procedure without removing the old, damaged valve.