• Willich SN et al. Am J Cardiol 1987 • Kelly-Hayes M et al. Strole 1995 • Elliott W. Stroke 1998
2000’s Circadian variation in haemodynamic, autonomic and hormonal systems synchronize to produce a high risk state
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ABPM: 24h BP profile
Blood Pressure
160 140 120 100
80 60 40 20
0 9:38 AM
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1:06 PM
SLEEP
5:02 PM TIME
9:58 PM
7:33 AM
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24h ABP monitoring
How should the curves be analysed?
There is general consensus that optimal BP control requires a smooth reduction in the 24h ABP profile
Control of morning BP may be the most important goal in the treated hypertensive patient
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Isolated clinic hypertension
or hypertension in evolution?
160 140 120 100
80 60 40
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Mr. M.L. ABPM profiles 1996, 1998
SLEEP
SBP1 SBP2 DBP1 DBP2
Clinical Indications
• Suspected isolated clinic hypertension • Suspected nocturnal hypertension • Suspected masked hypertension • To establish ‘dipper’ status • Resistant hypertension • Hypertension of pregnancy
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24h BP profile analysis
Mean day, night, 24h ABPM Minnesota cosinor method (Halberg et al 1967) Fourier analysis (Chau et al. 1989) Square wave model (Idema et al. 1991) Double logistic analysis (Head et al. 2002)
• Insufficient duration of action of antihypertensive drugs may be a key factor for high morning BP (Chonan K et al. Clin Exp Hypertens 2002)
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Masked hypertension (isolated ambulatory hypertension)
This phenomenon refers to patients in whom clinic BP is normal but blood pressure values by ABPM or self-BPM are increased Not uncommon:
2.85
2 1.81
2.23 1.67
1.00 1
3 Nighttime
2.51
2
1.86 1.71
1.41
1.00 1
0 <11.5 11.5- 13.9- 15.8- 18.8< 139 15.8 18.8
0 <8.1 8.1- 9.9- 11.8- 14.4< 9.9 11.8 14.4
Systolic BP Variability (mmHg)
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Kikuya, Imai et al. Hypertension 2000
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CV events according to blood pressure variability
Rate of events (per 100 patient-years)
9 8 7 6 5 4 3 2 1 0
AMBULATORY BLOOD PRESSURE
PROGNOSTIC SIGNIFICANCE
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EVENTS/100 patient years
CV MORBID EVENT RATE
Verdecchia et al. 1994 6
5
4
3
2
1
0
NT GROUP
HT 'WHITECOAT'
11:00 AM 3:00 PM 7:00 PM
11:00 PM 3:00 AM 7:00 AM
‘White-coat’ effect in hypertensive patients
Term used to describe phenomenon found in many hypertensive patients whereby clinic BP measurements are consistently greater than the BP values obtained by ABPM or self-BPM, the levels of which are nonetheless increased above normal
• Shows BP behaviour during usual daily activities
• A stronger predictor of cardiovascular morbidity and mortality than clinic BP
• Can identify patterns: ‘non-dippers’, isolated clinic hypertension, masked hypertension, enhanced BP variability, episodes of hypotension
Assessing prognostic relevance
• Discrepant information from different indices
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BP Variability and CV disease: Ohasama
Relative Hazard
*
3
Daytimep=0.01
• Weber MA Am J Cardiol 2002
Blood pressure variability
Different methods
• SD of the 24h average ABP • A ‘weighted’ 24h ABP SD (to account for
nocturnal BP fall) • Average real variability index (Mena et al 2005)
‘White-coat’ hypertension (isolated clinic hypertension )
‘ White-coat’ hypertension is a condition in which an individual is hypertensive during repeated clinic BP measurements, but outside the medical environment pressures measured by ABPM or selfBPM techniques are normal
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Recommended levels of normality for ABPM in adults (ESH guidelines 2005)
Optimal* Normal Abnormal
Awake <130/80 <135/85 >140/90
Asleep <115/65 <120/70 >125/75
*Lower optimal values recommended in diabetes mellitus and high-risk patients
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Rate of morning rise in BP, HR Hypertensive (n=51) vs Normotensive (n=63)
• 29% Gourlay S et al. J Hum Hypertens 1993, 7:467-72 • 22% PAMELA study Circ 2001, 104:1385-92
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Ambulatory blood pressure measurement (ABPM)
Low
Medium
High
BPVar (SD) BPVar (ARV)
Mena et al. J Hypertens. 23:505-12
Is 24h control of BP important?
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Yet to be determined the component of
the ABP profile that is the best predictor of prognosis, but…..