new 동맥경직도평가방법및임상적의의 · 2015. 7. 7. · central pulse pressure (pp)...
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동맥경직도 평가방법 및 임상적 의의
인제의대 부산백병원
김 동 수
Multiple Cycle of Pulsatile Stretch
Elastin Fiber Fracture
Aortic Dilatation and Stiffening
Arterial Damage
(arteriosclerosis)
(atherosclerosis)
(aneurysm formation)
Increased
Pulse Pressure
Increased Pulsatile Stress and Strain
Arterial stiffness, pulse pressure and arterial damage
Arterial Stiffness
Three processes to increase arterial stiffness
– Structural breakdown of elastin fibers
• occurs primarily in the aorta
• age driven (cum. millions of cardiac cycles)
– Damage to endothelial function
• occurs primarily in the smooth muscle conduit
arteries
• disease driven (e.g., Type II diabetes,
hypercholesterolemia, atherosclerosis)
– Increase in mean arterial pressure
• occurs systemically throughout the arterial system.
Mechanism of Arterial Stiffness
↑ Vascular stiffness / Distensibility
↑ Systolic blood pressure & Pulse pressures
↑ Atherosclerosis
IMT
Intimal migration/proliferation of VSMC
Vascular change
Collagen
Elastin
Endothelial
Dysfunction
Vascular anatomical changeArterial wall thickness (IMT)
Intimal migration/proliferation of VSMC
Subendothelial collagen
Collagen cross-linking
Elastin / Elastin fragmentation
Proteoglycans
Endothelial dysfunction Endothelial permeability
Endothelial nitric oxide , endothelin
Inflammatory markers/mediators
SOD activity
Medial wall
stiffness
CompliantSystole Diastole
Non-CompliantSystole Diastole
Constant Stroke Volume
Aorta
Pulse
pressure
Systolic BP
Diastolic BP
Arterial Wall Compliance and Pulse Pressure Wave
Curr Opin Cardiol 2004;19:341
Noninvasive Methodologies for the
Assessment of Arterial Stiffness
• Measuring Pulse Wave Velocity:
현재많이이용
• Relating change in diameter(or area) of an
artery to distending pressure
• Assessing arterial pressure waveforms:
Augmentation Index(AI), Central Aortic
Pressure, Pulse Pressure
• Known distance apart (d)
• Transit time (Δt)
Pulse Wave Velocity
* *a b
distance
A
B
A
B
t
The speed with which the pulse wave travels along a length
of artery (distance/t)
PWV = d/ Δt
Carotid art.
Femoral art.
distance
t
Noninvasive measurement of PWV
Aortic PWV
= distance (carotid-femoral art.) / t
Carotid-femoral PWV is considered as the ‘gold-standard’
measurement of arterial stiffness
Relating change in diameter(or area) of
an artery to distending pressure
• 초음파를사용하는방법으로 Carotid artery 에서 수축기와 확장기의직경을측정하고혈압과의관계 변화를계산하여평가한다.
• 혈압은일반적으로 Brachial artery에서 측정한혈압을사용한다.
• Brachial artery PP가 Carotid artery PP반영하지못해정확한 Carotid artery stiffness를 측정하기어렵다.
• Cine MRI를 이용하여근위부대동맥에서도일부 측정한다.
• 평가지표: Distensibility, Compliance, Young’s Elastic modulus, beta stiffness index
Brachial PPCentral PP
Laurent S, et al. Eur Heart J 2006 27:2588-2605
Local arterial stiffness
Parameter Definition Formula
Distensibility The relative change in vessel diameter (or
area) for a given change in pressureD/(PxD),
A/(PxA)
Compliance The absolute change in vessel diameter (or
area) for a given change in pressureD/P, A/P
Elastic modulus The pressure change required for
(theoretical) 100% stretch from resting
diameter (inverse of distensibility)
(PxD)/D
Stiffness index (ß ) The ratio of the natural logarithm of
SBP/DBP to the relative change in diameter
ln(Ps/Pd)
/ [(Ds-Dd)/Dd)]
Young’s modulus
(incremental elastic
modulus)
Elastic modulus per unit area (accounts for
wall thickness)(PxD)/(Dxh)
Definitions of some parameters commonly measured in
the assessment of local arterial stiffness
동맥의 압력맥파 (pressure wave)
진행파 (전향파형)
Forward wave
반사파 (반향파형)
Reflected wave
Observed wave
SBP
incisura
forward
reflected
건강한혈관경직된혈관
incisura
forward
reflected
Reflection site Reflection site
augmentation
Arterial stiffening
Pulse Wave Analysis
• Central pulse pressure
• Central aortic pressure
• Augmentation index (AIx)
경동맥또는요골동맥에서맥파를기록하여파형을분석
Radial artery
Pulse wave analysis (PWA) :
augmentation index (systemic art. stiffness)
Aorta
transfer function(Degree of amplification)
Radial pulse
Augmentation index
Sensor
Bone
Artery
applanation tonometry
Device to estimate pulse wave analysis
SphygmoCor
GAON (한별메디텍)
• Central pressure
• Pulse pressure(PP)(SBP-DBP)
= (P1-P3) + (P2-P1)
• AI = (P2-P1)/(SBP-DBP)
* PP = Pulse pressure
* AI = Augmentation index
* P2 = 최대수축기혈압
* P1= 반향파가돌아와서굴곡을만드는
최대지점
* P3 = 최소이완기혈압
* Δtp= 상행대동맥에서주요반향지점
까지파형이이동하는데걸리는시간
* Δtr = 반향파의수축기
Aortic pressure waveform
P1
SBP
DBP
incisura
ejection duration
PP
P2
P3
Δtp Δtr
Augmentation pressure★
parameter Main features and
definition
Limitations Technical
expertise
Carotid-
femoral PWV
Gold standard for arterial
stiffness
Speed of travel of the pulse
along an arterial segment
(L/t in m/s)
Pressure-dependent
No data on arterial geometry
Inaccuracy of distance
measurement
+
Central pulse-
wave analysis
(carotid and
aortic pressure
waves)
Central pulse pressure (PP)
Central SBP
Central augmentation
pressure (AP)
Central AIx with AIx = AP/PP
Indirect information on
arterial stiffness
+
Local arterial
stiffness
Carotid distensibility
Carotid compliance
Carotid Young’s modulus
Takes into account BP level
Requires echotracking
systems
Requires local PP
+++
Methods for measuring arterial stiffness in clinical investigation
PP
Increased CentralPulse Pressure
Increased LV Load
Decreased Coronary ArteryPerfusion Pressure in Diastole
Stiffened artery and clinical implication
Aortic arterial wave
Stroke
CHD
LVH
DiastoleSystole
Arterial Stiffness & CV Disease
↑ Central wave
Reflection
↑ Aortic stiffness
↑ Vascular endothelial damage
& Mechanical fatigue↑ PP
Atherosclerosis
- Stroke
- Myocardial Infarction
- Renal Failure
- LVH and CHF
- Myocardial stiffening
- Aneurysm formation
and rupture
↑Myocardial O2 demand
↓Coronary perfusion
Clinical conditions associated with increased
arterial stiffness and/or wave reflections
Laurent S, et al. Eur Heart J 2006 27:2588-2605
Multivariate analyses: the major parameters to be
taken into account, when evaluating the degree of
arterial stiffness, are age and BP and, to a lower
extent, gender and classical CV risk factors.
*Men aged 35-57 years followed for a mean of 12 years.
Neaton et al. Arch Intern Med. 1992;152:56-64.
<120120-139
140-159
160+
CHD Death Rate per
10,000 Person-Years
100+
80-89
70-74<70
75-79
90-99
Effect of SBP and DBP on CHD Mortality
48.3
37.4
43.8
38.1
80.631.0
25.5
25.325.2
24.9
23.8
16.9
13.9
12.8
12.6
11.8
20.6
10.311.8
8.8
8.5
9.2
Systolic BP
(mm Hg)
Diastolic BP
(mm Hg)
맥압과 심혈관 질환의 사망률
MRFIT Screenees (N=316,099)*
Clinical application
• Carotid-femoral PWV has the largest amount of epidemiological evidence for its predictive value for CV events.
• Central pulse pressure and the AIx have demonstrated their predictive value in patients with ESRD, in hypertensives, and in CAD patients.
• Local arterial stiffness benefits from a certain amount of epidemiological evidence for its predictive value for CV events.
REASON study:
PWV and augmentation index(AI)
Asmar R et al. Hypertens. 2001;38:922-926.
Aorta-AI (%)
Perindopril
+indapamide
Atenolol
P=0.112
P<0.001
-4
-3
-2
-1
0
1
2
-3.1
+1.8
PWV (ms)
P=0.002
-1.5
-1
-0.5
0
-0.79
-0.99
Perindopril
+indapamide
(n=204)
Atenolol
(n=202)
P<0.001 P<0.001
ns
With no difference of PWV Favorable with ACEi+diuretic of AI
CAFE: Lower central aortic BP with newer
vs older antihypertensive regimen
despite similar brachial BP
Amlodipine ± perindopril
Atenolol ± bendroflumethiazide
140
135
130
125
120
115
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6
Time (years)
mm Hg
Brachial SBP
Central aortic SBP
CAFE Investigators. Circulation. 2006;113:1213-25.
두 군의 약물치료에 의해 나타난 중심대동맥 혈압의 차이
CAFE: Lower augmentation index with
newer antihypertensive regimen
31.9
25.3
0
5
10
15
20
25
30
35
Augmentation
index
(%)
P < 0.0001
Amlodipine ± perindopril†Atenolol ± bendroflumethiazide*
CAFE Investigators. Circulation. 2006;113:1213-25.*Older antihypertensive regimen†Newer antihypertensive regimen
With no difference of PWV
Non-Pharmacological and pharmacological treatment associated
with a reduction in arterial stiffness: Interventional studies
Sildenafil
• Hypertension
- Re-stratification of patient risk
- Re-classification of marginal hypertension
- Optimisation of drug therapy
- Identification of spurious isolated systolic hypertension
• Cardiac failure
- Distinguish systolic vs diastolic dysfunction
- Determine severity of systolic dysfunction
- Precise measure of LV load
- Index of subendocardial viability
• Diabetes
- Early identification of cardiovascular risk
• Baro-receptor function
• Ischaemic heart disease
- Optimise medical therapy
- Identify patients with short end diastole
Clinical application of pulse wave analysis
동맥경직도 평가의 임상적 의의
• 심혈관계 질환의 표지자 뿐 만 아니라 치료에 대한예후를 예측
• 여러 약제의 동맥경화에 대한 치료효과를 평가
• 여러 질환에서 동맥경화가 발생하는 병태생리를연구하는 데 사용
A number of technologies can measure arterial stiffness noninvasively. The relatively low cost, ease of use, and acceptability to patients of many of these technologies has resulted in a rapid expansion of work in this field, although the full clinical impact of these measurements is not yet clear.