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ACI TECHNOLOGY
LEARN MORE ABOUT THE PROCESS
APPARATUS
The system, method, and apparatus consist of a blood pressure monitoring device configured to measure systolic and diastolic blood pressure; a blood flow velocity monitoring device configured to measure peak-systolic and end-diastolic blood flow velocities; and a central processing unit configured to calculate the ACI. The system can be incorporated into Doppler ultrasound equipment or other devices thereby providing on-screen real time indices of artery stiffness, distension, blood flow, flow resistance, and pressure gradients.
How it works
ACI MEASUREMENTS
BLOOD PRESSURE:
Systolic Blood Pressure (SP)
Diastolic Blood Pressure (DP)
BLOOD VELOCITIES OF ARTERY IN ISSUE:
Peak – Systolic Velocity (PSV)
End – Diastolic Velocity (EDV)
Artery Signature Waveform
Using blood flow velocities from the artery signature waveform, with systemic blood pressure, all hemodynamic variables such as forward and reflected pressure waves, shear stresses on the artery walls, and flow dynamics are incorporated.
EDV = Lowest blood velocity after peak-systolic velocity
RESULTS
Arterial Compliance Index (ACI) = Stored / Recoil pressure by the artery (mmHg).
Stored / recoil pressures or ACI values can be established for any artery relative to pulse pressure (PP/ACI).
Lower stored / recoil pressures are indicative of stiffer arteries (Stiffness = 1 / Compliance).
The Artery Equilibrium Equation Used:
Blood Pressure (Impedance) = Compliance (ACI) + Conductance
Total Energy = Stored Energy + Released Energy
ACIAAO = Compliance of Ascending Aorta (mmHg).
ACICA = Compliance of Carotid Artery (mmHg).
ACIRA = Compliance of Renal Artery (mmHg).
SP = ACIAAO – (ACICA – ACIRA) (DRIAAO + 1)
DP = ACIAAO – (ACICA – ACIRA)
PP = – (ACICA – ACIRA) DRIAAO
DRIAAO = PSV – EDV / EDV = Diastolic Resistive Index at the Ascending Aorta Artery
(ACICA – ACIRA) = Vascular Conductance
SP, DP, PP = Systolic, Diastolic, and Pulse Pressure
(1/DRIAAO) + (1/DRIRA) – (1/DRICA) = 0
ACIAAO = 93.33 mmHg
ACICA = 70 mmHg
ACIRA = 56.67 mmHg
(ACICA – ACIRA) = 13.33 mmHg
DRIAAO = -3.0 DRICA = 4 DRIRA = 1.71
PP/ACIAAO = 0.43
[(DP – ACIAAO) SV / PP] (HR) = 2.0 l/min = 2,000 ml/min (-) Retrograde.
ACI CARDIOVASCULAR
For Cardio-Renal studies, the ACI software calculates the ACI of the Ascending Aorta artery from screenings of the Renal and the Left Common Carotid arteries. In these cases, the cardiovascular, hypertension, and cerebrovascular risk indices can be compared and associated simultaneously.
Curr Opin Nephrol Hypertens 2012, 21:000–000 DOI:10.1097/MNH.0b013e32835856e3
The ACI derived indices provide cardiovascular risk assessment quantification from clinically established baselines. Calculations show that the ACI Cardiovascular Risk Index PP/ACIAAO associated with the stiffness of the Ascending Aorta Artery approaches 0.70 or higher in patients with cardiovascular disease.
ACI CORONARY FLOW INDEX
[(DP – ACIAAO) SV / PP] (HR) = Retrograde (-) diastolic flow in the AAO Artery
SV = Stroke volume (l or ml/1000) HR = Heart rate (beats/min)
Under normal conditions, both antegrade and retrograde blood flow occurs in the Ascending Aorta during diastole. The retrograde flow supports coronary arterial perfusion. This flow can be quantified and evaluated with the ACI Coronary Arterial Flow Index.
ACI CARDIOVASCULAR RISK INDEX
PP/ACIAAO = Pulse Pressure / Compliance of the Ascending Aorta Artery
Int J Cardiovasc Imaging (2011) 27:459–469
J R Soc Med Cardiovasc Dis 2012;1:18. DOI 10.1258/cvd.2012.012024
ACI APPLICATIONS
Arterial compliance and stiffness depend on the functioning of muscle cells, elastin and collagen within the artery walls. These structural elements support the pressure of blood exerted on the artery wall when distended and recoil the artery in order to maintain continuous blood flow through the arterial system. The elastic recoil action of the artery continues to apply inward pressure on the blood during the period of relaxation of the heart and forces the blood to maintain its diastolic flow. Thus, determining the elastic recoil pressure of arteries is of great importance in vascular studies.
Applications in the following areas:
- Blood pressure and organ function
- Hypertension
- Endothelial function
- Atherosclerosis
- Stenosis and plaque consistency
- Cardio-Renal autoregulation
- Biomolecular effect on arterial function
- Cardiovascular
- Aortic valve stenosis
- Stroke
- Intracranial pressure
- Cerebral perfusion pressure
- Mean arterial pressure and mean flow
- Systole and diastole times
- Arterial vascular function general
- Doppler US beam flow angle determination
- Other
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