CN101897574A - Chaotic calculation method of pulse wave velocity - Google Patents
Chaotic calculation method of pulse wave velocity Download PDFInfo
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Abstract
The invention relates to a chaotic calculation method of pulse wave velocity, which utilizes the properties that the chaos technology is sensitive to weak signals and can carry out effective statistics treatment, and the chaos technology is adopted for greatly improving the PWV measurement precision and the repeat consistency.
Description
Technical field
The present invention relates to a kind of medically to the chaos computational methods of pulse wave conduction speed.
Background technology
So-called PWV refers to the spread speed of pulse wave between two of Arterial system had both fixed a point, and PWV is the pressure wave speed of measuring along artery segment, and the theoretical basis of measurement depends on Moens-Korteweg formula: PWV
2=(Young mould .h/2r ρ), ρ is density of blood (usually about 1.05), h/2r is pipe thickness/intra-arterial diameter.The Young mould is represented the physical parameter of elastomeric material hardness.
In practice, PWV was calculated by the transmission time apart from/two pulses measure points.In its deep experimentation, PWV can measure the site (for example, large artery trunks) on the same route of same tremulous pulse.Yet, in a noninvasive clinical research, these two are measured the site is that tremulous pulse at the tangible body surface that arrives of body surface (is measured aortic PWV usually between carotid artery and femoral artery, measure upper limb PWV between carotid artery and the brachial artery, the PWV of carotid artery and radial artery measurement arm, the PWV of femoral artery and neck artery measurement thigh); Strictly speaking, these sites are not always on the same circuit of pulse transmission.The limitation of this technology on measuring is this method subject matter.
Except the age, tremulous pulse medicated porridge sample stiffness index and arterial stiffness, the PWV value also raises along with the rising of blood pressure, depends on the natural elasticity of the blood vessel wall that comprises the Young mould.This is second problem that PWV detects.Before being estimated, the actual effect of vascular performance got rid of the variation that influences blood pressure.Although these limiting factors are arranged, because its principle is simple, the PWV detection method is used widely, and PWV is not subjected to the influence of echo.
The water hammer formula
Characteristic impedance (Zc) is another index of measuring arterial stiffness, and it can obtain with flow speed wave and relevant frequency component thereof by measuring pulse pressure.When PWV and Zc are expressed as cm/s or dyne.s/cm
3Formula is as follows: Zc=1.330*PP (mmHg)/max F (cm/s)=PWV* ρ (ρ=1.05).This is called as the water hammer formula, and it and PWV and pressure and flow have direct relation.
According to the Moens-Korteweg equation, PWV is directly proportional with the square root of coefficient of elasticity, because the attenuating of arterial elasticity, pulse wave has been accelerated in the spread speed of Arterial system.In recent years, because this positive correlation of PWV and arterial stiffness, it is simple and easy to do and do not have wound to add its measuring method, so being widely used is used as assessing an index of arterial stiffness.
The result of study of Siebenhofer etc. more shows, through PWV value measured between the different research worker of training much at one, has shown fabulous repeatability.The repeatability that the Asmar professor adopts the Complior of all automatic measurement to check PWV to measure nineteen ninety-five, result further specify the PWV detection and have fabulous repeatability.At present, this measuring method has become " goldstandard " that PWV detects.
The relation of PWV and various diseases:
1) PWV and arteriosclerosis: arterial stiffness and age are proportionate, and this mainly is owing to blood vessel wall middle level degeneration, and the middle level collagen content increases, and causes elastic layer to rupture with advancing age, with mean fiberization and calcification.Other correlative factor comprises sex, smoking, hypertension, diabetes, hypercholesterolemia etc.And hypertension, tremulous pulse degeneration, cardiovascular disease have been aggravated arteriosclerotic process, and this variation is remarkable especially with center elastic force blood vessel as aorta.Arteriosclerosis has caused large artery trunks pooling feature obstacle again, cause that pulse pressure (PP) and systolic pressure (SBP) disproportionately increase, thus, the increase of left chamber afterload and increasing the weight of of coronary ischemia have been caused, coronary perfusion pressure reduces, systole pressure rises to, and increases chamber, end-systole left side stress, causes left ventricular hypertrophy.
2) prediction of PWV and end stagerenaldisease (ESRD) patient cardiovascular disease danger: ESRD patient is the high-risk group of cardiovascular disease.Epidemiological study and clinical research show that the trunk infringement is the main cofactor of ESRD patient's cardiovascular disease high incidence and mortality rate, and the trunk disease is made progress particularly rapid in uremic patient.The predicting function of PWV in ESRD patient can not be ignored.
3) PWV and diabetes: the increase of arterial stiffness is another feature of diabetics, and this may be because the cause that the glycosylation dead end product increases in the circulation.And in the type ii diabetes patient, the arteriotony monitoring is found continuously, and it is a universal phenomenon that BP raises.The arterial stiffness increase is relevant with diabetes, hyperglycemia, hyperinsulinemia and impaired glucose tolerance.In older adult, studies show that insulin resistant, hyperinsulinemia and hyperglycemia may promote arteriosclerotic generation and development, this effect is independent of the age and exists.Hyperglycemia can activate collagen protein decomposes, and causes proteoglycan to be deposited on arterial wall, thereby causes destruction, the sclerosis of arterial wall.Type ii diabetes increases the danger of some type trunk disease.In the crowd of west, CHD is the modal cause of death of type ii diabetes patient, and the danger that diabetic population is died from CHD has increased by 3 times approximately, and the dangerous increasing degree of non-lethality heart infarction and congestive heart failure is similar.Nephropathy is a common microvascular complication of type ii diabetes.In studying for a long period of time, the accumulation incidence rate that is diagnosed as the patient nephropathy of diabetes more than 20 years is about 27%-60%, occurs that the incidence rate of 10 years ESRD is about 10%-35% behind the albuminuria, and diabetes are main causes of most of westerner ESRD.ESRD patient's cardiovascular disease mortality rate with diabetes is higher, and this may be because diabetes have been aggravated the arteriosclerotic degree of patient.PWV is an extremely strong cardiovascular death and total dead predictor.About the predictor of PWV to ESRD patient's cardiovascular disease incidence risk.PWV is in application prospect and the prospect of cardiovascular disease aspect preventing and treating.
4) PWV and hypertension: PWV is relevant with the arterial wall stiffness index, and higher PWV has shown higher stiffness index.In order to reduce hypertensive patient's mortality rate, blood pressure should be reduced to which kind of degree, this is a question at issue.There are some researches show that the degree of depth reduction of hypertensive patient's blood pressure is associated with lower cardiovascular event; Controlling of blood pressure in the scope of strictness, can be reduced the danger of type ii diabetes people's trunk and microvascular complication, and it doesn't matter for the kind of this reduction and medicine for treatment.The blood pressure lowering of the prompting degree of depth may be beneficial to hypertensive patient's arterial wall.A recent research is observed, and 187 hypertensive patients that reach 150/87mmHg through blood pressure lowering treatment back blood pressure have the stiff phenomenon of aorta acceleration between the follow-up period in 6 years, show if blood pressure is even lower a bit, perhaps can prevent stiffization of aorta.In theory, the rapid decline of blood pressure can delay the propagation of pulse wave along arterial wall, thereby reduces PWV.So, can the level that allows blood pressure maintain between longer-term after the decline be improved PWV better? Atsuhiro Ichihara etc. has studied degree of depth blood pressure lowering and the appropriate blood pressure lowering The Long-term Effect to the hypertensive patient's of non-diabetic arterial wall stiffness index.The research is assessed the arterial wall stiffness index with the method for measuring baPWV (upper arm ankle pulse wave conduction speed).Assessment and compared the ratio that the PWV that treats back 3 months, 6 months, 9 months and 12 months in blood pressure lowering changes (Δ PWV) and blood pressure (Δ BP).The result shows that appropriate blood pressure lowering does not have to reduce hypertensive patient's PWV, and degree of depth blood pressure lowering has reduced hypertensive patient's PWV significantly.Though PWV has reflected functional and anatomy arterial wall elasticity, the result of this research points out, if the degree of depth is depressurized near normal level, and keeps at least 12 months, and anatomy elasticity can be improved.Therefore, PWV not only can forecast hypertensive patient's cardiovascular mortality and sickness rate, can also be as the index of hypertension long-term treatment controlling of blood pressure.
In cardiovascular disease, having proposed the arterial stiffness increase recently especially is the pathological state of blood vessel injury, and the cardiovascular diseases closely links to each other with the atherosclerosis type.And pulse wave conduction speed (PWV) is the indicator of arterial stiffness and the sign amount of arterial injury.Gage beam ankle PWV (baP-WV) can be used for atherosclerosis type cardiovascular diseases's diagnosis and management as a surrogate markers amount.
The famous laboratory Framingham in Europe studies show that, the hypertension incidence rate increases with the age and increases, age surpassed after 60 years old, and pulse pressure increases and the diastolic pressure reduction is the performance that large artery trunks elasticity reduces, and in fact hypertension quickened the stiff evolution of large artery trunks.It is that the peripheral vascular resistance increase causes that early-age shrinkage is pressed increase, and systolic pressure increase in late period then mainly is due to large artery trunks elasticity reduces.Left ventricular ejection produces the pressure to blood vessel, forms the pressure pulsation of propagating along blood vessel wall, i.e. PWV.Pulse wave can produce wave reflection at a certain crotch of Arterial system, depends primarily on reflection coefficient and arterial stiffness.Just often, PWV is relatively low, and echo is superimposed on the relaxing period of aortic pressure waveform, and this is useful to body.And increase with the age, the arterial wall structure changes, and arterial elasticity reduces, and PWV obviously increases.During hypertension, ductus arteriosus wall tension force is increased, long-term hypertension state can cause the blood vessel wall structural change.Therefore, the old and feeble and coefficient result of hypertension is that arterial elasticity reduces.PWV increases, when transmitting site is nearer apart from heart, causes the systolic pressure peak value to increase, and diastolic pressure reduces, and the pulse pressure level raises.AvDP reduces, and causes coronary perfusion to reduce, and contraction pressure in late period rises to, and causes left ventricular hypertrophy.
PWV judges the index that the peripheral arterial wall hardenability of substantial connection is arranged with cardiovascular and cerebrovascular disease.This principle of utilization " conduction velocity of the fluctuation (pulse wave) that the blood of being exported by heart when arteriosclerosis produces can be accelerated " is measured fluctuation (pulse wave) conduction velocity between 2 heart beatings, judges the elasticity of blood vessels degree.The hardened progress of peripheral arterial has the tendency prior to coronary atherosclerosis, so PWV can be used as the evaluation index of suffering from the future the coronary atherosclerosis disease risks, is the optimum prediction index of cardiovascular and cerebrovascular disease.PWV is very significant independent prediction factor to the death of all causes of the death especially cardiovascular disease.
In view of PWV and arteriosclerosis and hypertensive relation, PWV measures and is widely used in recent years.Blacher etc. are to about 530 researchs that the hyperpietic did prompting, according to the Framingham equation, existence and the degree of PWV and AA (aminoacid) have significant correlation, and PWV＞13mPs has very high using value as the strong predictor of causing danger property of cardiovascular disease.In not having atherosclerotic patient, along with the rising of PWV, myocardial infarction (MI), coronary heart disease (CHD), CHD mortality rate, apoplexy, cardiovascular disease (CVD) and CVD mortality rate all rise thereupon.The risk factor of all cardiovascular disease and the rising of PWV are linear correlation.And at any one age, large artery trunks PWV is the best predictor of cardiovascular disease mortality rate.Among the crowd, the relative risk (OR value) that cardiovascular death takes place PWV＞13-15m/s is 7.11 more than 60 years old.Asmar etc. show also that to the cross-sectional study of 1470 primary hypertension patients the rising of PWV and the existence of CVD have significant correlation, and this dependency is independent of antihypertensive therapy and exists.
Boutouyrie etc. study 1045 routine clinical no cardiovascular diseasess' hyperpietic, PWV the base line measurement patient, and calculate Framingham danger according to sex, age, blood pressure, cholesterol, diabetes and smoking situation and mark, assessment coronary heart disease is caused danger, and average follow-up period is 5.17.The result shows, in follow-up period 53 coronary events and 97 cardiovascular events has taken place altogether.Through univariate analysis, PWV spread speed enhancer, coronary events and occurrence of cardiovascular event are dangerous to be increased; PWV increases a standard deviation (3.15m/s), and the relative risk that coronary events takes place is 11.42 (P＜0.01), and the relative risk that cardiovascular event takes place is 11.41 (P＜0.001).Multivariate analysis shows that after the dangerous evaluation factor of Framingham was proofreaied and correct, PWV increased a standard deviation, and the relative risk that coronary events takes place is 11.34 (P=0.039); After well-known risk factor proofreaied and correct, the relative risk that coronary events takes place was 11.39 (P=0.01).Researcher thinks that PWV measures and helps to determine the coronary heart disease high risk patient, makes this part patient from benefiting the positive therapeutic more.
In sum, pulse wave conduction speed PWV is the index of a comparatively sensitive demonstration blood vessel elasticity, before not developing into hypertension, among progression of atherosclerosis, just may influence blood vessel elasticity, use the PWV analyzer and carry out early monitoring and intervention this moment, and positive supervisory function bit is played in the prevention and the treatment of old cardiovascular disease.
France in 1999, PWV are considered to the perspective study that cardiovascular disease also comprises end-stage renal disease patient patient's (ESRD) independently hazard factor at first.In this research, the ratio of PWV 〉=12m/s is 5.4 with respect to the mortality rate of PWV≤9.4m/s.This cohort study has also verified the accuracy of PWV at research institution of same institute another piece document.Do not have higher mortality rate and sickness rate according to the patient that ESRD is arranged than suffering from this sick patient; Therefore, there are a considerable amount of people to pay close attention to the predictability that PWV detects cardiovascular disease.Yet the nearest predictability that studies confirm that PWV detects of the same age is worth.
Another problem be exactly the predictability of PWV whether be to have the patient of potential cardiovascular disease or whether high PWV value representative suffers from cardiovascular disease.Some research hints that these two kinds of phenomenons are all possible.People such as Cruickshank advise that PWV may be cardiovascular hazard factor aggregative index (as, persistent period of hypertension or diabetes), can predict congenital cardiovascular disease.Opposite, significantly cardiovascular patient has high PWV value.
Except extensive population being studied the evidence of acquisition, another problem is the availabilities of two kinds of methods at clinical setting.The doctor is not easy to obtain PWA and PWV value with respect to the blood pressure measurement of routine.This is measured needs special equipment and well-trained operator to need new medical skill simultaneously.They need patient lying on the back to measure usually.Although these shortcomings are arranged, when by the effective method of large-scale people research and in clinical setting useful measurement become clear, PWA and PWV will be the instruments of necessity of cardiovascular doctor.
Multinomial studies show that normal people with advancing age its aorta PWV value can progressively raise, show as aortal decline and stiffness index.Such rising can make hyperpietic and cardiac's the state of an illness increase the weight of.The after-contraction that research also shows as radial nerve press the growth of amplification, carotid artery and master pulse are pressed to be increased with advancing age.Opposite, the data that Fu Lai is first from tomorrow, growth and the relationship with age of confirmation aorta PWV.People such as Adji report that the exponential growth of cardiovascular patient AIX gives a discount may give the credit to the effect of daily multiple cardiovascular disease medicine.They point out that also the AIX index is easy to change under the situation of Drug therapy; Yet PWV but is not like this.AIX relies on the flow waves profile, if the mobile minimizing of relative after-contraction is arranged, it may not can along with the age increases and raises.These viewpoint hints AIX detects with PWV has different effects in clinical setting.Utilization PWV detects, and the clinicist can understand the blood vessel stiffness index, can reflect patient's ill history.Can assess curative effect person's Drug therapy and normal ventricle by measurement AIX value and penetrate blood.The to slow down process of arterial stiffness of the AIX value that reduces.
Another problem that remains unsolved is an equipment, and these two indexes all affect cardiovascular system.The vicious cycle of a large artery trunks disease is proposed, and wherein high central large artery trunks causes arteriectasia and quickens elastic fiber fracture (Figure 10).This theory is based on engineering philosophy and the human achievement in research for observation that provides; Yet he can't be by experiment provides direct proof with the mankind's research, because in the past 20 years flexible breaking in elastic artery needs 800,000,000 extensions of beating.In addition, his not clear this theory can be applied to muscular artery; For instance, the target organ of coronary artery and peripheral arterial.Nearest studies show that, pulse pressure with coronarius break relevant, and than former think more deep; Therefore, in the future should be relevant for the investigation of the sickness rate of arterial stiffness.
Modern science and technology has brought advanced instrument with aortic flow and central artery stiffness index in the assessment clinical medicine.Although a lot of problems wait to solve, as 100 years foresleeve belt sphygomanometers, new method had the potentiality of pair cardiovascular research and practice innovation.
To the prospective research of PWV, can provide new strategy with the treatment cardiovascular disease.
Conventional P WV computational methods are as follows:
The starting point of pulse wave is to measure the key of PWV, and starting point is the time point that pulse wave starts, the moment=t of the moment-starting point 2 of propagation time T=starting point 1
a-t
b, starting point t
aAnd t
bVariation with the measuring object position changes, if measure the PWV value of lower limb, then starting point t
aBe the start time point of electrocardiographic wave, and starting point t
bBe the start time point of femoral artery pulse wave, PWV=L/T, L are the distances of two pulse waves of surveying.General measuring method is as follows:
The peak value rule of three is to obtain the peak of pulse wave (peak value) earlier, then with peak value 10% as starting point.
Derivative method is exactly that derivative maximum with pulse wave is as starting point.
The tangent line interior extrapolation method is that intersection point with pulse wave baseline and ascending curve is as starting point.
Bathmometry is to ask the pulse wave second derivative to determine starting point.
And that the common drawback of above-mentioned these detection methods is noise processed is not enough, and the signal of initial point position is little, and sound pollution is serious.
Chaos technology has characteristic responsive to small-signal and that can carry out effective statistical disposition, the Duffing system equation is by Duffing (1918), Moon and Holmes (1979,1980) propose, the equation prototype is the forced vibration equation of non-linear single pendulum, and the chaos basic function adopts Duffing Moon Holmes system model:
x″(t)+kx′(t)-ax(t)+b
3(t)＝rcos(ωt) (3.0)
Summary of the invention
The chaos computational methods of a kind of pulse wave conduction speed provided by the invention utilize chaos technology to have characteristic responsive to small-signal and that can carry out effective statistical disposition, adopt chaos technology, and PWV certainty of measurement and repetition concordance are improved greatly.
In order to achieve the above object, the invention provides a kind of chaos computational methods of pulse wave conduction speed, it comprises following steps:
The starting point t of step 1.1, calculating heart place pulse wave
aThe position;
Step 1.1.1, carry out chaos algorithm;
Y′(t)＝J(t)Y(t) (3.1)
J (t) is the state description matrix behind the formula 3.0 Duffing Moon Holmes system linearization of being constructed.
For a known dynamical system, its basic solution can be write by expression matrix:
Y(t)＝Q(t)R(t) (3.2)
Q is an orthogonal matrix, and R is that a diagonal element all is the upper triangular matrix of positive number, substitution formula (3.1), then:
Q′(t)R(t)+Q(t)R′(t)＝J(t)Q(t)R(t) (3.3)
Get by matrix properties:
R′(t)＝(Q
T(t)J(t)Q(t)) (3.4)
Step 1.1.2, employing Lyapunov algorithm carry out chaos to be judged, judges whether system chaos takes place;
Obtaining the Lyapunov performance index according to formula (3.2) and (3.4) is:
If the maximal Lyapunov exponent of chaos system is less than zero, illustrative system is non-chaos, maximal Lyapunov exponent is greater than zero, it is the necessary and sufficient condition that system is in chaos state, when the maximal Lyapunov exponent of system greater than zero the time, the time point " t " of this moment is exactly the starting point t of heart place pulse wave
a
Step 1.2, calculate starting point t away from the acra place pulse wave of heart
bThe position;
The pulse waveform at step 1.2.1, actual measurement acra place;
Step 1.2.2, the waveform that step 1.2.1 is obtained carry out power spectrumanalysis, obtain spectrogram;
Step 1.2.3, the peak value in the spectrogram is analyzed, obtained the frequency f (angular frequency=2 π f) and the amplitude r at peak value place;
Step 1.2.4, with angular frequency and amplitude substitution chaotic function that step 1.2.3 obtains, calculate the starting point t of acra place pulse wave
b=t;
x″(t)+kx′(t)-ax(t)+b
3(t)＝r
1cos(ω
1t)+r
2cos(ω
2t)+r
3cos(ω
3t)
(3.6)
R wherein
1, r
2, r
3, ω
1, ω
2, ω
3Be to try to achieve through power spectrumanalysis, just can calculate the tram of starting point according to the characteristic of chaotic function fast according to the PWV respective waveforms;
Step 4, calculate PWV;
PWV＝L/T。
The present invention adopts chaos technology, and PWV certainty of measurement and repetition concordance are improved greatly.
Description of drawings
Fig. 1 is the oscillogram of the femoral artery pulse wave of the actual measurement that provides in the specific embodiments of the invention;
Fig. 2 is that the waveform to Fig. 1 carries out the spectrum waveform figure that power spectrumanalysis obtains;
Fig. 3 is the measured waveform figure when system chaos does not take place among one group of embodiment;
Fig. 3 A is the phase-plane diagram of corresponding (3.6);
Fig. 3 B is the oscillogram of pulse wave;
Fig. 3 C is the sequential response curve of corresponding (3.6);
Fig. 4 is the measured waveform figure when system chaos does not take place among another group embodiment;
Fig. 4 A is the phase-plane diagram of corresponding (3.6);
Fig. 4 B is the oscillogram of pulse wave;
Fig. 4 C is the sequential response curve of corresponding (3.6);
Fig. 5 is the measured waveform figure during system's generation chaos among the embodiment;
Fig. 5 A is the phase-plane diagram of corresponding (3.6);
Fig. 5 B is the oscillogram of pulse wave;
Fig. 5 C is the sequential response curve of corresponding (3.6);
Fig. 6 is the pulse wave electrocardiographic wave that the actual measurement that provides in the example specifically is provided of reality of the present invention.
The specific embodiment
Following according to Fig. 1-Fig. 6, specify better embodiment of the present invention:
A kind of chaos computational methods of pulse wave conduction speed, it comprises following steps:
The starting point t of step 1.1, calculating heart place pulse wave
aThe position;
Step 1.1.1, carry out chaos algorithm;
Y′(t)＝J(t)Y(t) (3.1)
J (t) is the state description matrix behind the formula 3.0 Duffing Moon Holmes system linearization of being constructed.
For a known dynamical system, its basic solution can be write by expression matrix:
Y(t)＝Q(t)R(t) (3.2)
Q is an orthogonal matrix, and R is that a diagonal element all is the upper triangular matrix of positive number, substitution formula (3.1), then:
Q′(t)R(t)+Q(t)R′(t)＝J(t)Q(t)R(t) (3.3)
Get by matrix properties:
R′(t)＝(Q
T(t)J(t)Q(t)) (3.4)
Step 1.1.2, employing Lyapunov algorithm carry out chaos to be judged, judges whether system chaos takes place;
Obtaining the Lyapunov performance index according to formula (3.2) and (3.4) is:
Fig. 6 is the pulse wave electrocardiographic wave of actual measurement;
As shown in Figure 3 and Figure 4, chaos does not also take place in system;
As shown in Figure 5, system's generation chaos, the position of chaos origination point is shown in Fig. 5 B, in Fig. 5 A, the starting point of the pulse wave that this moment is corresponding is wave number=0.02 (wave number is a pulse wave each point corresponding voltage value), and at this moment the Lyapunov performance index value of being obtained by formula (3.5) is a maximum, shown in Fig. 5 B, corresponding time point is 18965, and it is multiplied by sampling time interval 0.003s, is 56.895 seconds.Be t
a=56.895 seconds;
Step 1.2, calculate starting point t away from the acra place pulse wave of heart
bThe position;
The pulse waveform (as shown in Figure 1) at step 1.2.1, actual measurement acra place;
Step 1.2.2, the waveform that step 1.2.1 is obtained carry out power spectrumanalysis, obtain spectrogram (as shown in Figure 2);
Step 1.2.3, the peak value in the spectrogram is analyzed, obtained the frequency f (angular frequency=2 π f) and the amplitude r (as shown in Figure 2) at peak value place;
r
1＝0.0245；r
2＝0.0175；r
3＝0.009；
f
1＝9；f
2＝18；f
3＝26；
ω
1＝2πf
1；ω
2＝2πf
2；ω
3＝2πf
3；
Step 1.2.4, angular frequency and amplitude substitution chaotic function that step 1.2.3 is obtained:
x″(t)+kx′(t)-ax(t)+b
3(t)＝r
1cos(ω
1t)+r
2cos(ω
2t)+r
3cos(ω
3t)
(3.6)
Calculate the starting point t of acra place pulse wave
b=56.782 seconds;
T=t
a-t
b=56.895-56.782=0.113 second;
Step 4, calculate PWV;
PWV＝L/T＝0.9/0.113＝7.96。
Claims (4)
1. the chaos computational methods of a pulse wave conduction speed is characterized in that, comprise following steps:
Step 1, calculate initial point position respectively;
Step 2, calculate pulse wave used time from the cardiac conduction to the acra: T=ta-tb;
Step 3, measure heart, i.e. distance L between two pulse waves to the distance between the acra;
Step 4, calculate PWV;
PWV＝L/T。
2. the chaos computational methods of pulse wave conduction speed as claimed in claim 1 is characterized in that, described step 1 comprises following steps:
The starting point t of step 1.1, calculating heart place pulse wave
aThe position;
Step 1.2, calculate starting point t away from the acra place pulse wave of heart
bThe position.
3. the chaos computational methods of pulse wave conduction speed as claimed in claim 2 is characterized in that, described step 1.1 comprises following steps:
Step 1.1.1, carry out chaos algorithm;
Y′(t)＝J(t)Y(t) (3.1)
J (t) is the state description matrix behind the formula 3.0 Duffing Moon Holmes system linearization of being constructed.
For a known dynamical system, its basic solution can be write by expression matrix:
Y(t)＝Q(t)R(t) (3.2)
Q is an orthogonal matrix, and R is that a diagonal element all is the upper triangular matrix of positive number, substitution formula (3.1), then:
Q′(t)R(t)+Q(t)R′(t)＝J(t)Q(t)R(t) (3.3)
Get by matrix properties:
R′(t)＝(Q
T(t)J(t)Q(t)) (3.4)
Step 1.1.2, employing Lyapunov algorithm carry out chaos to be judged, judges whether system chaos takes place;
Obtaining the Lyapunov performance index according to formula (3.2) and (3.4) is:
If the maximal Lyapunov exponent of chaos system is less than zero, illustrative system is non-chaos,
Maximal Lyapunov exponent is the necessary and sufficient condition that system is in chaos state greater than zero, when the maximal Lyapunov exponent of system greater than zero the time, the time point " t " of this moment is exactly the starting point t of heart place pulse wave
a
4. the chaos computational methods of pulse wave conduction speed as claimed in claim 2 is characterized in that, described step 1.2 comprises following steps:
The pulse waveform at step 1.2.1, actual measurement acra place;
Step 1.2.2, the waveform that step 1.2.1 is obtained carry out power spectrumanalysis, obtain spectrogram;
Step 1.2.3, the peak value in the spectrogram is analyzed, obtained the frequency f (angular frequency=2 π f) and the amplitude r at peak value place;
Step 1.2.4, with angular frequency and amplitude substitution chaotic function that step 1.2.3 obtains, calculate the starting point t of acra place pulse wave
b=t;
x″(t)+kx′(t)-ax(t)+b
3(t)＝r
1cos(ω
1t)+r
2cos(ω
2t)+r
3cos(ω
3t)(3.6)
R wherein
1, r
2, r
3, ω
1, ω
2, ω
3Be to try to achieve through power spectrumanalysis, just can calculate the tram of starting point according to the characteristic of chaotic function fast according to the PWV respective waveforms.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN102551698A (en) * | 2011-12-16 | 2012-07-11 | 广州医学院第二附属医院 | Neck and brain arterial pulse wave speed measurement system |
| CN104622440A (en) * | 2015-02-09 | 2015-05-20 | 中国科学院深圳先进技术研究院 | Punctuating method and device in pulse wave extraction |
| CN106714674A (en) * | 2014-09-29 | 2017-05-24 | 微软技术许可有限责任公司 | Wearable sensing band for pulse transit time computation |
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2009
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN102551698A (en) * | 2011-12-16 | 2012-07-11 | 广州医学院第二附属医院 | Neck and brain arterial pulse wave speed measurement system |
| CN102551698B (en) * | 2011-12-16 | 2015-03-18 | 广州医学院第二附属医院 | Neck and brain arterial pulse wave speed measurement system |
| CN106714674A (en) * | 2014-09-29 | 2017-05-24 | 微软技术许可有限责任公司 | Wearable sensing band for pulse transit time computation |
| CN104622440A (en) * | 2015-02-09 | 2015-05-20 | 中国科学院深圳先进技术研究院 | Punctuating method and device in pulse wave extraction |
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