Pre­vious mea­su­re­ment methods — Miss­ing the target

Blind man’s bluff ins­tead of clear vision

Why the limi­t­ed view of con­ven­tio­nal car­dio­vas­cu­lar dia­gno­stics is at the expen­se of the­ra­peu­tic suc­cess and pati­ent health. 

Pre­vious mea­su­re­ment methods

Miss­ing the target

Take the most cir­cui­tous rou­te thinkable: The tra­di­tio­nal approach used so far to deter­mi­ne arte­ri­al stiffness. 

This is not an exag­ge­ra­ti­on — it accu­ra­te­ly descri­bes dai­ly car­dio­vas­cu­lar dia­gno­sis rou­ti­nes. Ever­y­thing revol­ves around mea­su­re­ment data that are bey­ond any doubt. But whe­re cla­ri­ty, unam­bi­guous­ness, and the hig­hest pre­cis­i­on of the values mea­su­red would be of the hig­hest importance to pre­vent and tre­at car­dio­vas­cu­lar dama­ge and secon­da­ry dise­a­ses, cir­cui­tous sur­ro­ga­te para­me­ters pre­vail. Often, the­se para­me­ters poor­ly reflect the true con­di­ti­on of the arte­ries and give an ina­de­qua­te, often even error-pro­ne account of the indi­vi­du­al car­dio­vas­cu­lar status.

The under­ly­ing pro­blem lies in the gene­ral dif­fi­cul­ty of obtai­ning relia­ble vas­cu­lar data: The wall pro­per­ties of arte­ries can­not easi­ly be deter­mi­ned direct­ly in living humans.

This limi­ta­ti­on beco­mes even more important when it comes to the func­tio­ning of an enti­re arte­ri­al tree. Howe­ver, it would be par­ti­cu­lar­ly important to be able to ana­ly­ze this in detail: Name­ly, to cla­ri­fy, depen­ding on the indi­vi­du­al case, how ener­gy-effi­ci­ent­ly and even­ly — or not — the blood trans­port to the respec­ti­ve organs takes place. Based on this, con­clu­si­ons can be drawn about the respec­ti­ve phy­si­cal pro­per­ties of the heart and arte­ries and any risks.

The short­co­ming of tra­di­tio­nal diagnostics


The prin­ci­ple of con­ven­tio­nal pul­se wave ana­ly­sis is based on iden­ti­fy­ing the arterial/cardiovascular pro­per­ties of a pati­ent by the shape of the pul­se wave. With this approach, the spe­ci­fic con­di­ti­on of the ves­sels in each case can be read pri­ma­ri­ly from the stiff­ness of the arte­ri­al walls: The lower their ela­s­ti­ci­ty due to depo­si­ted plaques, the hig­her the risk of life-threa­tening car­dio­vas­cu­lar events such as heart attack or stro­ke in par­ti­cu­lar. It is also pos­si­ble to extra­po­la­te from the pul­se wave­form to the cen­tral blood pres­su­re, i.e. the aor­tic pressure.

The cru­cial weak­ne­ss of all tra­di­tio­nal mea­su­re­ment methods is the exclu­si­ve­ly indi­rect deter­mi­na­ti­on of arte­ri­al stiff­ness via sur­ro­ga­te para­me­ters such as pul­se wave velo­ci­ty (PWV), aug­men­ta­ti­on index (AIX), or flow-media­ted dila­ti­on (FMD). The­se para­me­ters are pre­do­mi­nant­ly based on dif­fe­rent metho­do­lo­gi­cal vari­ants, all of which mea­su­re the pul­se wave wave­form at the upper arm, wrist, or fin­ger. The sur­ro­ga­te para­me­ters thus obtai­ned then pro­vi­de the mea­su­re of the ela­s­ti­ci­ty or stiff­ness of the arteries.

Howe­ver, due to the round­about deter­mi­na­ti­on, the accu­ra­cy and tracea­bi­li­ty of the values fall by the way­si­de. In addi­ti­on, the­se auxi­lia­ry para­me­ters often report limi­ta­ti­ons in arte­ri­al dis­ten­si­bi­li­ty, which is the most sen­si­ti­ve mar­ker of arte­ri­al func­tion, much too late, i.e., only when the first signs of dise­a­se are alre­a­dy appa­rent. In addi­ti­on, the Dopp­ler method, for exam­p­le, which is often used in the con­text of pAVK scree­ning, only ever records arte­ri­al pres­su­re sel­ec­tively, i.e. rela­ted to a sin­gle artery. This can lead to a fal­se pic­tu­re of the actu­al con­di­ti­on of the arte­ries — in the worst case, nar­ro­wings (steno­ses) are over­loo­ked.  Thus, most of the con­ven­tio­nal approa­ches to mea­su­re­ment data acqui­si­ti­on fall short of the task at hand, which is ear­ly dia­gno­sis and pre­ven­ti­on of car­dio­vas­cu­lar disease.

In con­trast to the pre­vious, defi­ci­ent dia­gno­stic stan­dard, indi­vi­du­al­ly tail­o­red, model-based pul­se wave ana­ly­sis can be used to deter­mi­ne a who­le ran­ge of new para­me­ters that not only pro­vi­de unri­va­led detail­ed insight into the vas­cu­lar sta­tus of pati­ents but also offer added value in terms of effec­ti­ve pre­ven­ti­on of car­dio­vas­cu­lar events. The­se include pres­su­res that can be mea­su­red direct­ly in the model, par­ti­cu­lar­ly aor­tic pres­su­re (cBP). More about the new para­me­ters.