4. Endothelium function Pulse amplitude tonometry (Endo-PAT 2000; Itamar Medical, Caesarea, Israel) is a peripheral endothelium function test, a non-invasive determination of digital endothelium function. This test will be performed following a light breakfast in the morning after 20 min rest and with the patient in a supine position. The PAT device is placed on the tip of each index finger and comprises a pneumatic pletysmography that applies a uniform pressure to the surface of the distal finger, allowing measurement of pulse volume changes. The inflation pressure of the digital device is electronically set to 10 mmHg below diastolic blood pressure or 70 mmHg. The PAT signal is recorded at baseline and following 5 min arterial occlusion using a inflatable cuff, while the contralateral arm serves as a control. The blood pressure cuff is inflated to 60 mmHg higher than systolic pressure or at least 200 mmHg for 5 min. Lack of residual pulsatility is monitored throughout the occlusion period. The post-occlusive hyperemia stimulates endothelium-dependent vasodilatation, causing an increase in digital pulse amplitude. Pulse amplitude is recorded electronically in both fingers and analysed by a computerised, automated algorithm (Itamar Medical). The change from the baseline measurement is expressed as the reactive hyperemia index (RHI), which in part reflects vasodilator function of the digital microcirculation.