Method and device for monitoring and improving arteriogenesis

Abstract

A method for determining an arteriovascular condition of a subject having an arterial blood flow is shown. The method involves determining a temporal progression of an instantaneous blood flow condition of the arterial blood flow as well as deriving a slew rate of the temporal progression during an increase of the temporal progression. In addition, an arteriovascular condition indicator device is shown, which comprises: an input for receiving an input signal representing an instantaneous arterial blood flow condition of a subject and a slew rate monitor connected to the input. A corresponding control device for providing an activation signal is also shown. The control device comprises a maximum detector connected to the slew rate monitor. A method for stimulation of arteriogenesis is also shown, wherein a temporal progression of an instantaneous blood flow condition is monitored, a slew rate of the temporal progression is derived, and the maximum of the slew rate is determined. An external pressure is applied repeatedly to the arteriovascular section in synchronization with the occurrence of the determined maximum.

1 . A method for determining an arteriovascular condition of a subject having an arterial blood flow, comprising: determining a temporal progression of an instantaneous blood flow condition of the arterial blood flow; deriving a slew rate of the temporal progression during an increase of the temporal progression; and determining the maximum of the slew rate, wherein the arteriovascular condition is determined by a value representing the maximum of the slew rate. 
     
     
         2 . The method of  claim 1 , wherein determining the temporal progression of the instantaneous blood flow condition comprises a step of measuring at least one of the following physical quantities: an instantaneous blood flow velocity, an instantaneous fluid pressure or an instantaneous shearing force within an arteriovascular section of the subject, the method further comprising a step of determining the blood flow condition according to a predefined function of at least one of the physical quantities. 
     
     
         3 . The method of  claim 2 , wherein the value representing the maximum of the slew rate corresponds to (a) the maximum slew rate of the instantaneous blood flow velocity, (b) the maximum slew rate of the instantaneous fluid pressure, or (c) the maximum slew rate of the instantaneous shearing force, or (d) one of these maximum slew rates normalized by a mean value of the blood flow velocity, of the fluid pressure or of the shearing force or (e) one of these slew rates normalized by the ratio of the mean value of the blood flow velocity, of the fluid pressure or of the shearing force to the cross sectional diameter of the arteriovascular section or to a fraction thereof. 
     
     
         4 . The method of one of the preceding claims, wherein deriving the slew rate of the temporal progression comprises: determining the slew rate by deriving the progression of the blood flow condition with respect to time; or determining the slew rate by relating an increase of the progression to the distance of time spanned by the increase. 
     
     
         5 . The method of one of the preceding claims, wherein the temporal progression is represented by a time-discrete blood flow condition signal comprising at least two values of the same positive slope or by a time-continuous blood flow condition signal comprising at least one positive slope. 
     
     
         6 . The method of one of the preceding claims, comprising determining a measure for an arteriogenic capacity of the subject, wherein the method comprises repeatedly determining a variation of the arteriovascular condition with a repetition in time intervals greater than 5 days, wherein the variation of the arteriovascular condition is in monotone increasing relationship to a measure for an arteriogenic capacity of the subject reflecting the progress of an arteriovascular condition of the subject or reflecting a response on physical training of the subject; wherein the measure for the arteriogenic capacity is determined according to the variation and the relationship. 
     
     
         7 . The method of one of the preceding claims, wherein the vascular condition is determined by a plurality of consecutive individual arteriovascular condition determinations and by averaging the resulting individual arteriovascular conditions, or by identifying the maximum of the resulting individual arteriovascular conditions. 
     
     
         8 . The method of one of the preceding claims, wherein determining a temporal progression of a blood pressure quantity comprises measuring blood flow properties within an arteriovascular section of the subject by laser Doppler velocimetry, sonography or magnetic resonance imaging of the arteriovascular section, or by pressure sensoring according to wrist blood pressure monitoring, finger blood pressure monitoring, sphygmomanometry, plethysmometry, plethysmography, or intravascular blood pressure sensing, or impedance measurements of tissue or at the arteriovascular section or at a myocardial section. 
     
     
         9 . The method of any one of the preceding claims, wherein a relative peak shear index (RPSI) and/or a pulse shear index (PSI) is determined. 
     
     
         10 . An arteriovascular condition indicator device, comprising: an input ( 10 ) for receiving an input signal representing an instantaneous arterial blood flow condition of a subject; a slew rate monitor ( 20 ) connected to the input ( 10 ), the slew rate monitor ( 20 ) relating variations of the blood flow condition to a distance of time spanned by the variation, the slew rate monitor ( 20 ) providing a slew rate representing the variations; a maximum detector ( 30 ) connected to the slew rate monitor ( 20 ) for receiving the slew rate, the maximum detector ( 30 ) being suited to identify and to provide a maximum slew rate to an output element ( 50 ) of the indicator device, the output element ( 50 ) being connected to the maximum detector ( 30 ) and being suitable to output a representation of the maximum slew rate as an indicator for the arteriovascular condition. 
     
     
         11 . The indicator device of  claim 10 , wherein the slew rate monitor ( 20 ) comprises a differentiator adapted to provide a derivation of the input signal as the slew rate or wherein the slew rate monitor ( 20 ) comprises a division unit adapted to divide an increase of the input signal by the distance of time spanned by the increase and to provide the result as the slew rate. 
     
     
         12 . The indicator device of  claim 10  or  11 , wherein the maximum detector ( 30 ) comprises a comparator suitable to compare successive slew rates provided by the slew rate monitor with each other and to provide the higher slew rate as the maximum slew rate to the indicator device ( 50 ) or to a memory of the indicator device adapted to store a maximum slew rate for retrieval by the indicator device, the memory being connected to the maximum detector as well as to the output element. 
     
     
         13 . The indicator device of one of  claims 10 - 12 , further comprising an averaging unit ( 40 ), the averaging unit ( 40 ) being connected between the maximum detector ( 30 ) and the output element ( 50 ), the averaging unit ( 40 ) being suitable to average a plurality of successive maximum slew rates output by the maximum detector ( 30 ) and to provide the average of the maximum slew rates to the output element ( 50 ). 
     
     
         14 . The indicator device of one of  claims 10 - 13 , further comprising a normalizer, the normalizer being suited to normalize the input signal representing an instantaneous arterial blood flow condition, the slew rate representing the variations, or the maximum slew rate by division by a normalization factor, wherein the input is suited for receiving values representing the blood flow condition as a blood flow velocity, a fluid pressure or a shearing force, the normalization factor being provided by: (i) a mean value of the blood flow condition as a result of an averaging unit; or by (ii) a ratio of the mean value of the blood flow condition to a cross sectional diameter of the arteriovascular section or to a fraction of the cross sectional diameter, the ratio being provided by a normalization base input of the indicator device. 
     
     
         15 . The indicator device of any of  claims 10 - 14 , wherein the device determines a relative peak shear index (RPSI) and/or a pulse shear index (PSI). 
     
     
         16 . A control device for providing an activation signal comprising: an input for receiving an input signal representing an instantaneous arterial blood flow condition of a subject; a slew rate monitor connected to the input, the slew rate monitor relating variations of the blood flow condition to a distance of time spanned by the variation, the slew rate monitor providing a slew rate representing the variations; a maximum detector connected to the slew rate monitor for receiving the slew rate, the maximum detector being suited to identify a point of time at which the maximum slew rate occurs, and to provide a signal to an activation output of the control device synchronized to the point of time of the maximum slew rate, the activation output being suited to output the activation signal upon receipt of the signal provided by maximum detector. 
     
     
         17 . An actuator device comprising a control device according to  claim 14 , the actuator device further comprising an actuatable surface as well as an actuator element mechanically connected thereto, the actuator element being connected to the activation output and being adapted to move the actuatable surface in response to the activation signal. 
     
     
         18 . A method for stimulation of arteriogenesis, comprising: determining a temporal progression of an instantaneous blood flow condition of the arterial blood flow through an arteriovascular section of a subject; deriving a slew rate of the temporal progression during an increase of the temporal progression; and determining the maximum of the slew rate, wherein an external pressure is applied repeatedly to the arteriovascular section in synchronization with the occurrence of the determined maximum. 
     
     
         19 . A method according to  claim 17  wherein said external pressure is repeatedly applied to the arteriovascular section by an external counterpulsation device which is controlled by an arteriovascular condition indicator or control device. 
     
     
         20 . The method according to  claim 19 , wherein the arteriovascular condition indicator or control device is for determining a relative peak shear increase (RPSI) and/or a pulse shear index (PSI). 
     
     
         21 . The method according to  claim 19 , wherein the arteriovascular condition indicator or control device is as defined in any of  claims 10  to  16 .