Clinical context Pulse Wave Velocity (PWV) is a non-invasive and simple method used as an index of large artery elasticity and stiffness. However, PWV measurement is modulated by blood pressure level at the time of the measurement (thus sensitive to the "white-coat" effect) and is operator-dependent. The QKd is an alternate method to measure PWV during an ABP monitoring in the auscultatory mode. The QKd interval is the time interval between the onset of the QRS on the electrocardiogram (Q) and the last Korotkoff sound (K) corresponding to the diastolic pressure (d). It allows to automatically derive the QKd100-60 index which is totally independent of the BP level, fully reproducible and insensitive to the "white-coat" effect (ambulatory recording). The clinical validation and the pronostic value of the QKd100-60 index have been established by several clinical studies. QKd100-60 index is a parameter available with all Novacor ambulatory blood pressure monitors featuring Ausculatory mode.
Novacor 's scientific publications
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ARTERIAL STIFFNESS PREDICTS SEVERE PROGRESSION IN SYSTEMIC SCLEROSIS: THE ERAM STUDY Joël Constans(a), Christine Germain(b), Philippe Gossec(c), Jacques Taillard(a),
Kiet Tiev(d), Isabelle Delevaux(e), Luc Mouthon(f), Claude Schmidt(g),
Florence Granel(h), Pascale Soria(i), François Lifermann(j), Gabriel Etienne(k),
Fabrice Bonnet(l), Karim Zoulim(m), Dominique Farge-Bancel(n), Isabelle Marie(o),
Yannick Allanore(p), Jean Cabane(d), Alain Amonchot(q), Isabelle Macquin-Mavier(r), Objective Methods Results Conclusion Journal of Hypertension 2007, 25:1900–1906 Keywords (a)Vascular and Internal Medicine Unit, CHU Bordeaux, (b)Clinical Epidemiology Unit, CHU Bordeaux, (c)Cardiology and Hypertension Unit, CHU Bordeaux, (d)Internal Medicine Unit, CHU Saint-Antoine, Paris, (e)Internal Medicine Unit, CHU Clermont-Ferrand, (f)Internal Medicine Unit, CHU Cochin, Paris, (g)Vascular Medicine Unit, CHU Nancy, (h)Dermatology Unit, CHU Nancy, (i)Internal Medicine Unit, CHU Limoges, (j)Internal Medicine Unit, CHG Dax, (k)Internal Medicine and Tropical Diseases Unit, CHU Bordeaux, (l)Internal Medicine and Infectious Diseases Unit, CHU Bordeaux, (m)Internal Medicine Unit, CHU Caen, (n)Internal Medicine Unit, CHU Saint-Louis, Paris, (o)Internal Medicine Unit, CHU Rouen, (p)Rheumatology Unit, CHU Cochin, Paris, (q)Cardiology Unit, CHU Clermont-Ferrand, (r)Clinical Investigation Unit, CHU Henri Mondor, Créteil and (s)Clinical Investigation Unit, CHU Nancy, France PROGNOSTIC VALUE OF QKD INTERVAL CORRECTED BY QRS DURATION IN HYPERTENSIVE PATIENTS P. Gosse(1), R. Lasserre(1), C. Minifie(1), P. Lemetayer(1) (1) Hopital Saint André, Bordeaux, France Objectives Methods
Results Conclusion Abstract: P3.255 Arterial stiffness evaluated by measurement of the QkD interval is an independent predictor of cardiovascular events Philippe GOSSE, MD; Raphael LASSERRE, MD; Catherine MINIFIE, MD; Philippe LEMETAYER, MD; Jacques CLEMENTY, MD Background Methods Results Conclusions Keywords: Arterial stiffness, QKD interval, ambulatory measurement of blood pressure, cardiovascular complications, hypertension American Journal of Hypertension, AJH 2005;18:470-476 Beyond blood pressure measurements: monitoring of the appearance time of Korotkoff sounds Philippe Gosse, Corinne Braunstein and Jacques Clementy We have recently proposed a new method to evaluate the physical properties of arteries based on measurement of the QKD interval together with blood pressure arid heart rate with an ambulatory blood pressure monitoring device. This interval is the time Key words: ambulatory blood pressure monitoring, arterial distensibility Assessment of Arterial Distensibility by Monitoring the Timing of Korotkoff Sounds Philippe Gosse, Pascal Guillo, Gilles Ascher, and Jacques Clementy The timing of Korotkoff sounds, blood pressure, and heart rate can now be monitored in the ambulatory patient the QKD interval is the time between the onset of the depolarization on the electrodiogram (Q) and detection of the last Korotkoff sound (K) at the level of brachial artery during cuff deflation, corresponding to diastolic blood pressure (D). Because this interval is inversely related to pulse wave velocity, this recently developed device enables evaluation of the influence of blood pressure on arterial rigidity, providing valuable information on the properties of the arteries. In this study, we examined the influence of hypertension and age on the above parameters and their correlations to left ventricular mass. QKD interval, blood pressure, and heart rate were monitored over a period of 24 h (four measurements/hour) in 33 normotensive and 70 untreated essential hypertensive patients. The slopes of the plots of QKD interval versus systolic and pulse pressure during the 24 h were calculated for each patient. The influence of age and hypertension on these slopes was tested by comparison of matched groups and multivariate analysis. Moreover the relationships between these parameters and echocardiographically assessed left ventricular mass were studied in 37 patients. We found a reduction in mean QKD interval with age and hypertension, reflecting the recognized higher pulse wave velocity in these patients. The slopes of the plots of QKD interval versus blood pressure were also lower in these patients, indicating the smaller influence of a change in blood pressure on pulse wave velocity in patients with stiffer arteries. Both average 24-h systolic blood pressure and the slope of QKD interval versus pulse pressure were significantly and independently correlated to left ventricular mass index. The influence of blood pressure on arterial rigidity can be evaluated by this new monitoring device. Our results showed that pulse wave velocity was less affected by a change in blood pressure in the patients with the stiffer arteries. Key words : Pulse wave velocity, arterial distensibility, hypertension, ambulatory blood pressure monitoring, Korotkoff sounds. American Journal of Hypertension 7, p.228-233, 1994Relationship between arterial distensibility and left ventricular function in the timing of Korotkoff sounds (QkD internal) . An ambulatory pressure monitoring and echocardiographic study Philippe Abassade, Yves Baudouy. Cardiology. Timing of Korotkoff sounds (QKd) is the time interval between Q wave ECG and pressure diastolic sound, determined by a routine ambulatory pressure monitoring (AMP) (Diasys Integra, Novacor). It is known to be an arterial distensibility index. However, this interval time includes pre-ejection time (PET) which is related to left ventricular (LV) function. The aim of the study is to define the relative influences of LV function and arterial distensibility in QKd interval. Sixty consecutive patients, with or without cardiac disease, out or in-hospital, were included. Patients with left bundle branch block, pace maker, or atrial fibrillation were excluded. The echocardiography-Doppler (ED) study collected LV function index : Shortening Fraction (SF), Ejection Fraction (EF), stroke index (SI), (PET), ejection time (ET). Pulse Wave velocity (PWV) was determined by ED in two points of the descending thoracic aorta. The AMP study collected-usual-pressure data : systolic (Ps), diastolic, mean (Pm), pulse pressure (Pp), simultaneously with PWV and over 24h. An automatic assessment of the QKd interval simultaneously with PWV was performed by the monitoring device. Another arterial distensibility index was calculated from ED and AMP: QKd is correlated with PWV (n = 53 , p = 0.007, r = 0.37), with Burton index (n = 50 , p = 0,001, QKd is correlated with CV function index like FE (n = 55, p < 0,001, r = 0,66), Ps/systolic diameter No correlation was found between QKd and EF when PET are withdrawn from QKd (n = 35, p = 0.21, QKd interval is a composite index which reflects not only arterial distensibility but also LV function. Key words : Arterial distensibility, left ventricular function, echocardiography. American Journal of Hypertension 15:4, p.67A, 2002PROGNOSTIC VALUE OF AMBULATORY MONITORING OF QKD INTERVAL TO ASSESS ARTERIAL STIFFNESS IN HYPERTENSIVE PATIENT Philippe Gosse*, Raphael Lasserre*, Catherine Minifié*,
Philippe Lemetayer*, Jacques Clementy*
Objective Design
and methods Results
Conclusion Journal of Hypertension, volume 21 (Suppl. 41), June 2003, page S245, abstract P3.67 Prognostic
Value of Ambulatory Measurement of the Timing of Korotkoff Sounds
in Elderly Hypertensives, a Pilot Study Alteration
of arterial distensibility in systemic sclerosis Assessment
of arterial distensibility in hemodialyzed patients. Is it related to
secondary hyperparathyroidism (HPT)? AJHI994I7: 228-233 Changes
on arterial distensibility induced by hormonal replacement therapy in
both hypertensive and normotensive post-menopausal women: non-invasive
ambulatory assessment Effect of age on vascular compliance in man: which are the appropriate measures? C. Rajkumar, J.D.
Cameron, J.S. Joshi, D. Lyons, P. Nihoyannopoulos, C.J. Bulpitt. Introduction Design and Methods Results |
| Intercept unadjusted |
Slope unadjusted |
Slope adjusted for SBP |
Slope adjusted for DBP |
%Decrease 40-55 years |
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| Carotid toe interval | 220 | -0.518** | -0.660** | -0.594* | 3.9 |
| QKd Interval | 223 | -0.783* | -0.521 | -0.780* | 6.1 |
| CAC | -95 | -0.032* | -0.028 | 0.033* | 13.0 |
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