Validation of Arteriograph – A New Oscillometric Device to Measure Arterial Stiffness in Patients on Maintenance Hemodialysis
Nemcsik J. · Egresits J. · El Hadj Othmane T. · Fekete B.C. · Fodor E. · Szabó T. · Járai Z. · Jekkel C. · Kiss I. · Tislér A.
Kidney Blood Press Res 2009;32:223–229 (DOI: 10.1159/000228935)
Background: Measuring arterial stiffness (augmentation index (AI), aortic pulse wave velocity (PWV)) in hemodialysis (HD) patients has prognostic significance. To assess its validity, the new oscillometric Arteriograph device (AIA, PWVA) was compared to the validated PulsePen tonometer (AIP, PWVP). Methods: AI and PWV were measured in 98 patients with both devices before HD. Validity was evaluated by Pearson’s correlation, Bland-Altman analysis, and by assessing the prognostic value of AI and PWV to predict cardiovascular (CV) mortality over 29 months. Results: Correlation between AIP and AIA was significant (R = 0.527, p < 0.001). The mean difference of AI values obtained by the two devices was –20.6%, and 30% of the paired AI differences fall outside the ±1 SD boundary of the mean between-device difference. There was no significant correlation between the PWVP and PWVA readings (R = 0.173, p = 0.097). The average difference of PWV values by the two devices was –1.2 m/s, and 20.6% of the paired PWV differences fall outside the ±1 SD boundary. In survival analyses, only PWVP but not PWVA was significantly related to CV mortality. Conclusion: Lack of correlation between PWVP and PWVA and lack of prognostic significance of PWVA suggest limited validity of Arteriograph to determine PWV in patients on HD.
Smoking and Hypertension Associated With Greater Arterial Stiffness in People Aging With HIV
By Fred Furtado
November 8, 2013
Having HIV is not independently associated with arterial stiffness -- a trait linked to cardiovascular disease risk -- despite HIV-infected individuals having a modest, but clinically significant, increase in arterial stiffness when compared to their uninfected counterparts. Instead, factors such as smoking and hypertension may account for the increase, according to study results presented at EACS 2013 in Brussels, Belgium.
To provide some background, HIV infection has been associated with an increased risk of cardiovascular disease and one of the markers for this condition is arterial stiffness, which is measured by pulse wave velocity (PWV), or how fast blood moves through the circulatory system. With age, or other changes to the arterial wall, blood vessels become stiffer and blood moves faster through the system, giving the heart less time to rest. PWV is directly dependent on mean arterial pressure (MAP) and past research has shown that an increase of 1 m/s (meter per second) in PWV is associated with a 14% greater incidence in total cardiovascular events.
However, studies measuring PWV in HIV-infected patients have been small and their results inconsistent. So, researchers led by Katherine Kooij, M.D., compared PWV in a cohort of HIV-infected and HIV-uninfected people to determine if there is an independent association between HIV and PWV, as well as possible determinants of PWV.
The study included 566 HIV-infected and 511 HIV-uninfected individuals, all 45 or older. Both groups had comparable median ages (52.8 versus 52), gender distribution (89.1% men versus 86% men) and proportion of men who have sex with men (76.4% versus 71.4%). However, the HIV-infected group included more current smokers (32.9% versus 24.8%) and users of antihypertensive drugs (31.3% versus 22.4%). The HIV-infected participants also displayed higher levels of inflammation and immune activation markers, such as hs-CRP and sCD163.
The researchers performed three measurements of PWV, as well as systolic and diastolic blood pressure, using an Arteriograph system, which registers oscillometric pressure waves in the aorta through an upper arm cuff. Additional information on potential determinants of arterial stiffness was collected with laboratory measurements and questionnaires. The data underwent a statistical analysis with multivariable linear regression models using PWV as a dependent variable, adjusted for MAP.
The analysis revealed a slightly higher, but significant unadjusted PWV in HIV-infected individuals than in HIV-uninfected individuals (7.9 m/s versus 7.7 m/s, P = .004). When these results were adjusted for MAP and gender, the difference between the two remained at 0.19 m/s (P = .04). If compared to a PWV increase due to age (+0.29 m/s per 5 years older, P < .001), having a positive HIV status would be the equivalent of being 3 to 3.5 years older.
However, when the PWV values were adjusted for other factors, such as smoking and use of antihypertensive drugs, HIV-infected status was no longer independently associated with arterial stiffness. In this setting, the difference between HIV-infected and HIV-uninfected PWV was only 0.022 m/s (P = .8). In contrast, every 5 pack-years (smoking 20 cigarettes a day per year, about 7,305 cigarettes) for current smokers accounted for a difference of 0.121 m/s (P < .001), while use of antihypertensive drugs represented an increase of 0.527 m/s (P < .001). The researchers also found that the inflammation marker hs-CRP and the monocyte activation marker sCD163 were associated with a higher PWV: 0.039 m/s (P = .001) and 0.056 m/s (P = .04), respectively. But sCD163 was only a significant determinant in men.
Arteriograph is a diagnostic instrument which is able to measure the severity of arteriosclerosis. This is the condition of arterial blockage caused by inflammation or damage within arteries
followed by an over production of a compound known as plaque created by the body to repair the damage. Plaque is made up of cholesterol, minerals such as calcium, specialised red blood cells
known as platelets and other clotting factors.
The Arteriograph is a simple and painless, non invasive investigation that can diagnose arteriosclerosis at an early stage .
Symptoms of arterial blockage include chest pain from blocking heart arteries, or the loss of sensation, numbness, or cramp in the lower limbs as the leg arteries block. These symptoms tend not to occur until a considerable amount of an artery is blocked and other arteries are no longer able to offer effective collateral circulation. Symptoms of cardiovascular disease leading to heart attacks and strokes usually appear only in the last and late stages and so arterial disease remains unrecognised through most of its development. The importance of identifying diseased arteries is clear.
Current investigations are not designed to detect early occlusion of blood vessels. The Gold Standard exercise or stress ECG (where an individual is placed on a running track with leads on their chest attached to the ECG), will not necessarily change until 70% of a coronary (heart) artery is blocked. More sensitive investigation such as angiography are invasive and demand radiation through x-rays and the injection of a 'dye' to show up the arteries. About 1 in 500 angiographies cause serious or even fatal events and this figure is even higher if you take patients who have chest symptoms. These methods of investigation are effective only in diagnosing late stage disease and can carry risks.
The results of the Arteriograph closely correlate to the invasive tests specifically the Coronary Calcium Score and afore mentioned Coronary Angiography with the advantage of avoiding the adverse events.
Statistics involving arterial disease
Arteriosclerosis is the cause of 40% of premature mortality. It is the main cause of heart attacks and strokes and can begin at the age of 20 although the consequences generally appear in our sixth decade. If we were able to diagnose early stage disease we would reduce these negative figures and the Arteriograph, taking only a few minutes and measuring both small and large artery resistance (the medical term for flexibility) is a sensible and valid method of testing the entire arterial system.
Approximately 48,000 people between the age of 30-69 have a heart attack each year here in the UK and 150,000 people suffer a stroke.
An individual simply has to avoid food for 3 hours prior to the test and should not drink alcohol for 10 hours nor have any caffeine for 6 hours. You shouldn’t be smoking anyway but that should not happen for at least 3 hours as well! Supplements and drugs that influence blood pressure should not be stopped unless authorised by your GP or prescribing doctor. Most such medication in most people can be stopped for a few days without any longer term risk allowing a clear indication of a patient's arterial status.
After lying down without movement and thinking nice thoughts for a few minutes then a blood pressure cuff is inflated around the upper arm for a few seconds. Other than some tightness no other discomfort is felt.
The specialised computer inflates the cuff two or three times as it establishes the measurements and the nurse will also add in some specific details including the length from your neck to the base of your abdomen – the length of your aorta.
The whole process can take as little as 20 minutess
The doctor reading the results will be able to comment on:
The results are provided to you (and any practitioners of your choice) with a guide to interpretation.
The benefits of early diagnosis
It is very important to recognise that early diagnosis of arterial disease allows for intervention that is capable of slowing down the progress of arterial disease and at best possibly reverse the condition.
Assessment of arterial stiffness in hypertension: comparison of oscillometric (Arteriograph), piezoelectronic (Complior) and tonometric (SphygmoCor) techniques.
Arterial stiffness, measured as aortic pulse wave velocity (PWV), and wave reflection, measured as augmentation index (AIx), are independent predictors for total and cardiovascular morbidity and mortality. The aim of this study was to compare a new device, based on oscillometric pressure curves (Arteriograph), which simultaneously measures PWV and AIx, with standard techniques for measuring PWV (Complior) and AIx (SphygmoCor) in untreated hypertensive patients.
We compared PWV and AIx measured using the Arteriograph with corresponding Complior and SphygmoCor measurements in 254 untreated hypertensive patients, age 48 +/- 14 years (mean +/- SD, range 17-85 years).
Arteriograph PWV and AIx were closely related with Complior (r = 0.60, P < 0.001) and SphygmoCor (r = 0.89, P < 0.001), respectively. Using stepwise regression analysis, the independent determinants of Arteriograph PWV were age, mean arterial pressure, heart rate and sex (r(2) = 0.44, P < 0.0001) and for AIx were age, weight, mean arterial pressure, heart rate and sex (r(2) = 0.65, P < 0.0001). The bias between the different techniques was determined by age and sex for PWV and age, body weight, sex, heart rate and mean arterial pressure for AIx. Bland-Altman plots showed that although the techniques were closely related, the limits of agreement were wide.
Although Arteriograph values and the determinants of PWV and AIx are in close agreement with corresponding parameters obtained by Complior and SphygmoCor, respectively, the techniques are not interchangeable.