A central aortic pressure wave was synthesized from the measured brachial artery pressure wave with the SphygmoCor XCEL system (AtCor Medical; Sydney, Australia), which uses a transfer function and is FDA approved. Central pressures and augmentation index (AIx) were obtained from the synthesized wave. AIx is an index of wave reflection and is influenced by arterial stiffness. AIx is calculated as the ratio between augmented pressure and central pulse pressure, or AIx = (P2–P1)/(Ps–Pd), where P1 is first shoulder of systolic pressure, P2 is second shoulder of systolic, Ps is peak systolic pressure, and Pd is end-diastolic pressure. Measures were performed in triplicate.
Sphygmocor xcel system
Manufactured by AtCor Medical
Sourced in Australia, United States
The SphygmoCor XCEL system is a noninvasive device that measures central blood pressure and arterial stiffness. It uses applanation tonometry to capture arterial pressure waveforms, providing objective data on cardiovascular health.
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30 protocols using sphygmocor xcel system
1
Central Aortic Pressure Wave Analysis
2
Blood Pressure Measurement Protocol
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Blood pressure was measured using a SphygmoCor XCEL system (AtCor Medical Pty Ltd). Preceded by 7 minutes in supine position at rest, systolic and diastolic blood pressures were measured at the brachial artery up to 3 times. The mean values for systolic and diastolic blood pressure were used (shown as SBP and DBP, respectively) in the following equation to derive an estimated mean arterial pressure (shown as MAP):
3
Vascular and Lipid Assessments
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BP and vascular measures were assessed with the SphygmoCor XCEL system (AtCor Medical) at the end of each diet period and following the run-in diet. Fasting serum lipids [total cholesterol (TC), triglycerides] and lipoproteins (LDL cholesterol, HDL cholesterol, non-HDL cholesterol) were measured by a commercial laboratory (Quest Diagnostics) on 2 consecutive days. Additional details are published elsewhere (15 ).
4
Central Aortic Pressure Wave Synthesis
5
Deriving Central Aortic Hemodynamics
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Central (aortic) BP represents the BP acting directly on internal organs like heart and kidney and have been found to independently predict cardiovascular outcome [15 (link)]. A validated system (SphygmoCor XCEL System; AtCor Medical, Sydney, Australia) was used to derive the central systolic BP (cSBP) and central pulse pressure (cPP) [16 (link)]. Brachial artery pressure curves were recorded from the brachial artery, with the patient being in a supine position, using a high-fidelity applanation tonometer (Millar Instruments, Houston, Tex.), directly into the SphygmoCorTM System which then calculated the corresponding central aortic waveform. After previous calibration, corresponding central (aortic) waveforms were automatically calculated from the brachial artery waveform by a validated transfer function. From the derived central waveforms, data for cSBP, cPP, forward and backward wave amplitude were provided.
6
Synthesizing Central Aortic Pressure Wave
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A central aortic pressure wave was synthesized from the measured brachial artery pressure wave with the SphygmoCor XCEL system (AtCor Medical, Sydney, Australia), which uses a transfer function and is FDA approved [34 (link)]. AIx was obtained from the synthesized central pressure wave and calculated as the ratio between augmented pressure and central PP, or AIx = (P2−P1)/(Ps−Pd), where P1 is first shoulder of systolic pressure, P2 is second shoulder of systolic, Ps is peak systolic pressure, and Pd is end-diastolic pressure. Measures were performed after a 20-minute supine rest. An average of 3 measures was reported.
7
Ambulatory BP Monitoring and PWV Assessment
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All patients had their medical history taken and underwent physical examination and collection of anthropometric data. All participants were fitted with ambulatory BP monitor (Spacelabs; Mobil‐O‐ Graph IEM GmbH; OSCAR‐2 SunTech) which were programmed to take 4 measurements per hour in the day‐time (06:00‐22:00 h) and 2 measurements per hour during the night‐time (22:00‐06:00 h), and the total average of the systolic and diastolic reading was used. PWV was performed using SphygmoCor Xcel system (AtCor Medical Pty Ltd) as per manufacturer's protocol at trough in a supine position. PWV was measured twice, and the average was used for analysis.
8
Aortic Stiffness Measurement via Carotid-Femoral PWV
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Carotid-femoral PWV, a gold standard for assessing arterial stiffness [35 (link)], was measured using applanation tonometry and the Sphygmocor XCEL system (AtCor Medical, Sydney, Australia). Carotid and femoral pressure waveforms were recorded simultaneously using a high-fidelity strain-gauge transducer (Millar Instruments, Houston, TX, USA) placed over the carotid artery and a BP cuff placed on the upper thigh, respectively. PWV distance was measured using the subtraction method where proximal distance (carotid measurement site to the sternal notch) was subtracted from distal distance (sternal notch to the thigh cuff). Carotid-femoral PWV was calculated by dividing the measured aortic distance (distal–proximal) by the average measured time delay between the initial upstroke of the corresponding carotid and femoral waveforms. The measure was performed while the subject was in a supine position. The measure was performed once.
9
Arterial Stiffness Assessment Protocol
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Arterial stiffness was assessed by non‐invasive pulse wave analysis (PWA) and pulse wave velocity (PWV) performed with the SphygmoCor XCEL system (AtCor Medical Pty Ltd, Australia) in accordance with manufacturer's recommendations. PWA was performed after a 5‐minute rest period in the supine position, an automatic 10 seconds PWA reading was used for data acquisition. Simultaneous measurements through applanation tonometry over the carotid and femoral artery provide the pulse transit time. The time elapsed between carotid and femoral artery sites was used to calculate pulse wave velocity. The capturing time for PWV assessment was set to 10 seconds with a PWV distance and subtraction method. PWV assessments were performed twice, and their average used for further analysis. PWV was expressed as distance/transit time (m/s). Several hemodynamic parameters were documented including central mean arterial pressure (cMAP), aortic augmentation pressure (AP) and augmentation index (AIx). AIx was normalized for a heartbeat of 75 beats per minute to enable comparations and was expressed as percentage.
10
Vascular Stiffness Measurement Protocol
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Vascular stiffness was measured by both carotid-femoral PWV (m/s) and pulse wave analysis (PWA). PWV and PWA were measured using the SphygmoCor XCEL System (Atcor Medical, Sydney, Australia) using the average of 3 readings that passed internal quality control measures on the device. In addition, AIx75 and percent wave reflection from PWA were measured. AIx75 is calculated from augmentation pressure (AP), which is the difference between the primary outgoing wave and the reflected wave of the central arterial waveform, and pulse pressure (PP). The full formula used was AIx75 = AP/PP, indexed to a heart rate of 75 beats per minute to adjust for the effect of heart rate as suggested by previous studies [13 (link)].
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