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ACI TECHNOLOGY

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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

ACI DIAGRAM

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).

BLOOD PRESSURE / AUTOREGULATION
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
CALCULATED BASELINES (Based on 120/80 mmHg Blood Pressure)
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.

“Arterial stiffness has great potential as a tool to help unravel the complexities and optimal treatment of cardiorenal disease.” 
Methods for Assessing Arterial Stiffness: Technical Considerations
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

“Impaired aortic distensibility (ADI) is associated with the severity of coronary atherosclerosis independent of age, gender, and cardiovascular risk factors. Furthermore, addition of ADI to traditional risk factors and coronary artery calcium score (CAC) provided the largest contribution to detect significant coronary atherosclerosis, and highlights the diagnostic utility of ADI in the early detection and monitoring of patients with atherosclerotic cardiovascular disease by a single noninvasive diagnostic study.”
Impaired Aortic Distensibility Measured by Computed Tomography is Associated with the Severity of Coronary Artery Disease
Int J Cardiovasc Imaging (2011) 27:459–469
“The cardiovascular disease spectrum is changing to one involving considerations of arterial disease beyond those caused by obstruction and ischemia to the progressive stiffening of the aorta and central elastic arteries.”
Arterial Stiffness
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.

The ACI Software provides clinicians an advanced tool to gain insight into vascular hemodynamics by establishing indices for the diagnosis and treatment of vascular issues.  The technology includes a comprehensive analysis in blood pressure, artery stiffness, compliance, and vascular resistance including artery distension and flow.

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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