Introduction

The blood pressure measurement device for an inside view of the arteries

The blood pressure measurement device for an inside view of the arteries

arteries

Detailed imaging diagnostic of PAOD is associated with high costs and complexity and is therefore not suitable for mass screening in daily medical practice.

Vascassist gives you the possibility of cardiovascular diagnosis based on automatic blood pressure measurement but offering far more information than is usually the case.

  • Determination of blood pressure using four blood pressure cuffs simultaneously applied to both upper arms and both ankles
  • Fully automated calculation of the Ankle-Brachial-Index as required in many guidelines as a specific indicator of PAOD
  • Measurement of pulse wave velocity as a parameter of the arterial vessel stiffness and as a further indicator of arterial vessel stenosis
  • Visualization of pulse pressure waves for diagnostic interpretation
  • Pulse frequency and dysrhythmia can be displayed
  • Comparison between blood pressures on the right and left sides of the body

From this and other information:

  • multifaceted conclusions about the state of the arteries can be drawn,
  • the degree of vessel stenosis can be determined,
  • indications of the formation of collateral circulation can be found,
  • the cardiovascular risk can be assessed
  • or rare forms of arterial disease can be diagnosed.

What can you identify using Vascassist?

(Measurement protocols of the optional Vascviewer software as examples)

  messung1  
Without pathological findings

All measurement values of ankle-brachial index and pulse wave velocity are in the normal range (shown with a green background). No indication of arterial vascular disease.

The pulse wave velocity is shown in the diagram not as an absolute value but normed for age, gender and current blood pressure, (as a percent divergence from the normal value). This enables pathological changes or changes inappropriate to the patient’s age to be easily recognized.

The 'traffic signal' colors used help to make the measurement results understandable for the patient.

 
  messung2  
Stiffening of the arteries

The measurement values lie above the (green) normal range and the pulse wave velocity is noticeably raised on both sides.
In the course of an atherosclerotic process this finding may be noticed at an early stage and indicates the need for further regular observation. The raised pulse wave velocity can be interpreted as an early indication of PAOD.

This finding of stiffening of the arteries can also be assigned to a discrete pathophysiology, which is associated with increased cardiovascular risk and which should be treated.

The pulse wave velocity, by the way, is just as suited for the diagnosis of arterial stiffening as the augmentation index, which is significantly more difficult to determine reliably (See study results).

Vascassist offers you possibly the quickest and simplest current possibility to diagnose arterial stiffening.

 
  messung3  
Light PAOD

The measurement values have moved into the red range and indicate an initial to light PAOD. The measurement values
on the right side of the body (green circles) show considerably lower ABI and baPWV values than the left side
(yellow stars) and indicate a more pronounced vascular stenosis on the right hand side of the body.

The further the measurement values go into the red range the more pronounced the PAOD is.

 
  messung9  
Pronounced PAOD

This measurement protocol shows unquestionably the typical measurement values of a pronounced arterial occlusive disease. The ankle-brachial index for both sides lies between about 0.5 and 0.7 and the pulse wave velocity lies about 70% below the statistically expected value for a test person of the same age and gender and with the same blood pressure.

As an supplement to the previous diagram it is clear here that with the progressive severity of pronounced PAOD the measurement values move along a diagonal from the green normal range to the red zone at lower left.

With severe circulatory disturbance in the legs pulsation at the ankles becomes scarcely measureable, so that for ABI values below about 0.4 the precision of automatic blood pressure measurement naturally decreases. This measurement range is fully sufficient for the intended purpose of VASCASSIST to identify asymptomatic vascular damage in screening early and to document its further progress. If there is clear indication of PAOD further diagnostic investigation using imaging equipment is in any case recommended for the exact localization of arterial constrictions (Angiography).

 
 

messung4

 
Subclavian stenosis

The pulse wave velocity values for the left side of the body (yellow stars in the diagram on the left) are situated at the upper edge of the diagram. However, in fact the pulse wave velocity is only apparently raised.

Actually the arm pressure curve was so chronologically delayed by a constriction of the arm artery (for example through subclavian stenosis or through the thoracic outlet syndrome) that the calculation resulted in a very short difference in transit time and thus a high pulse wave velocity.
So this finding often indicates a rare PAOD of the upper part of the body or the result of mechanical effect on the relevant arteries.

 
  messung5  
Compensated PAOD

In some cases a PAOD reveals itself less through the ankle-brachial index than through a significant reduction of the pulse wave velocity. When there is sufficient formation of collateral circulation the blood supply to the lower extremities can be largely normalized. Nevertheless the significantly reduced pulse wave velocity here is a strong indication of vascular disorders.   
In this case of mediasclerosis with falsely high ABI values a reduction of pulse wave velocity such as this may be the only indication of PAOD obtainable using a screening procedure. It is currently being investigated in a clinical study whether this represents a breakthrough in cardiovascular care for diabetics.

 
  messung6  
Mediasclerosis

An ankle-brachial-index larger than 1.4 indicates the presence of mediasclerosis, which often occurs in diabetic and dialysis patients.

In these cases also characteristic changes in the pulse pressure curves enable a PAOD to be diagnosed.

Mediasclerosis has its own medical significance!

 
  messung7  
Aneurysma

This was an incidental finding which demonstrates the versatility of diagnostic evidence given by Vascassist.

The 64 year-old male patient was routinely checked up for PAOD. Only a reduction of pulse wave velocity on the right side was noticeable. A following ultrasonography of the stomach and pelvic arteries showed a slight abnormal distension of the A. illiaca communis.  

A current study is investigating whether on the basis of this observation with Vascassist a reliable screening diagnostic method can be established for aneurysma of the large blood vessels.

 
  kurven_normal  
Pulse pressure curves: Normal finding

Together with the four-quadrant diagram for the measurement results of the ankle-brachial index and pulse wave velocity Vascassist’s measurement protocol also shows the recorded pulse pressure curves. These give additional information about arterial status. This can lead especially in the case of otherwise unclear findings to an unambiguous assessment.

The pressure curves from the four blood pressure cuffs are shown. Red stands for upper arm measurements, blue for ankle curves.

As PAOD to 90% affects the lower limbs the blue ankle curves are more relevant in the search for evidence of arterial stenosis.

In the normal situation the blue ankle curves are slightly higher than the red upper arm curves as the blood pressure in the feet is about 10% higher than in the upper arms. The form of the curves for healthy blood vessels is axially symmetrical with a relatively steep rising edge corresponding to the form of the relevant falling edge.

 
 

kurven_stenotisch

messung8

 
Pulse pressure curves: arterial stenosis of the lower limbs

In the evaluation of this measurement protocol the limited height of the blue ankle curves is immediately conspicuous in comparison to the previous measurements from a different patient. In addition the blue curves show a significantly more drawn-out rising edge. The curve appears stretched out on the time scale and flat, and at the maximum rounded and smooth ("pulsus tardus, parvus, mollis").

In the four-quadrant diagram the same measurement protocol shows measurement values, which are already outside the normal range but not yet definitely in the red zone. With the traditional ABI measurement using a hand-held Doppler probe for PAOD screening the ABI values between 0.9 and 1.0 would not have resulted in an unambiguous PAOD diagnosis. In contrast Vascassist very clearly shows a vascular anomaly in the sense of an arterial stenosis in all the diagram sections of the measurement protocol.

This shows clearly that Vascassist reacts very early and sensitively to vascular changes. This makes it a unique measurement device for a comprehensive early recognition program!

 

 

Compensated PAOD