arterial hemodynamics

American Journal of Hypertension

ajh.oxfordjournals.org

Am J Hypertens (2005) 18 (S4): 15A. doi: 10.1016/j.amjhyper.2005.03.035

P-17: A new and fast screening method for measuring complex hemodynamical parameters and arterial stiffness non-invasively with a simple arm cuff

Miklos Illyes1

+ Author Affiliations

1TensioMed Ltd., TensioMed Ltd, Budapest, Hungary

Abstract

Aims: In a project of the National Research Program of Hungary, we studied if oscillometric signals received during an oscillometric BP measurement contain any information about arterial hemodynamics

Materials, Methods: We have developed a research tool by which not only SBP, DBP, HR data, but the complete oscillometric signals were stored and transmitted telemedically to our computer center from the home of 650 patients who performed BP measurements at least 4 times a day, for at least 1 month. Through this a large database was collected, containing more than 1700000 oscillometric pulse curves and the relevant clinical data of patients. For data mining we used Kohonen's self-organising map method. Non-invasively recorded oscillometric curves from the upper arm cuff were validated by the simultaneously recorded intraarterial pressure curve of brachial artery.

Results: Our researches showed that oscillometric pulse curve of the brachial artery is identical to the intraarterial pressure curve if the cuff was inflated to suprasystolic pressure, preferably 35 mmHg above the SBP. Thus the early and the late systolic pressure peak, the closing incisure of the aortic valve can be recognizable, and several hemodinamical parameters could be calculated.

By using the mentioned results of basic researches, a new instrument, the TensioClinic Arteriograph was developed, by which the following parameters could be measured within 2 minutes, by using a simple upper arm cuff:

SBP, DBP, HR, MAP, PP, augmentation index (AIx), normalized augmentation index to 80/min heart rate (AIx80), return time of the pulse wave of the aorta (RT), pulse wave velocity (PWV) of the aorta, length of the cardiac cycle, area of systolic (SAI) and diastolic (DAI) part of pulse curve.

Validation studies of the new method to control the accuracy of measured AIx and PWV showed high correlations (R = 0,76 and R = 0,8) with values measured with other non-invasive methods (Sphygmocor and Complior) respectively.

Conclusions: Due to the swiftness, simplicity and good reproducibility of this method and apparatus, the non-invasive assessment of the most important hemodynamical parameters and arterial stiffness had become available for population screening, opening a new window in the detection of the early phase of the athero- and arteriosclerosis, and thus it can play an important role in the reduction of the CV morbidity and mortality.

 

非観血 連続 ワイヤレス 携帯 解析出力付き 相対血圧計

cardiac output results measured by the NICaS versus thermodilution

Physiol. Meas. 27 (2006) 817–827 doi:10.1088/0967-3334/27/9/005
Impedance cardiography revisited
G Cotter1, A Schachner2, L Sasson2, H Dekel2 and Y Moshkovitz3
1 Divisions of Clinical Pharmacology and Cardiology, Duke University Medical Center, Durham,
NC, USA
2 Angela & Sami Sharnoon Cardiothoracic Surgery Department, Wolfson Medical Center, Israel
3 Department of Cardiac Surgery, Assuta Hospital, Petah Tikva, Israel
E-mail: gad.cotter@duke.edu
Received 7 February 2006, accepted for publication 9 June 2006
Published 5 July 2006
Online at stacks.iop.org/PM/27/817
Abstract
Previously reported comparisons between cardiac output (CO) results in
patients with cardiac conditions measured by thoracic impedance cardiography
(TIC) versus thermodilution (TD) reveal upper and lower limits of agreement
with two standard deviations (2SD) of approximately ±2.2 l min−1, a 44%
disparity between the two technologies. We show here that if the electrodes
are placed on one wrist and on a contralateral ankle instead of on the chest, a
configuration designated as regional impedance cardiography (RIC), the 2SD
limit of agreement between RIC and TD is ±1.0 l min−1, approximately
20% disparity between the two methods. To compare the performances of
the TIC and RIC algorithms, the raw data of peripheral impedance changes
yielded by RIC in 43 cardiac patients were used here for software processing
and calculating the CO with the TIC algorithm. The 2SD between the TIC
and TD was ±1.7 l min−1, and after annexing the correcting factors of the
RIC formula to the TIC formula, the disparity between TIC and TD further
declined to ±1.25 l min−1. Conclusions: (1) in cardiac conditions, the RIC
technology is twice as accurate as TIC; (2) the advantage of RIC is the use
of peripheral rather than thoracic impedance signals, supported by correcting
factors.
Keywords: cardiac output measurements, thoracic bioimpedance, whole-body
bioimpedance, impedance cardiography
Introduction
Three basic technologies are currently in use for impedance cardiography (ICG): (1) the
thoracic ICG (TIC), where the electrodes are placed on the root of the neck and the lower
part of the chest, being the dominant method in the market (Patterson et al 1964, Kubicek
0967-3334/06/090817+11$30.00 © 2006 IOP Publishing Ltd Printed in the UK 817
818 G Cotter et al
et al 1966, 1974); (2) the whole-body ICG (ICGWB), where four pairs of electrodes are used,
one pair on each limb (Tischenko 1973, Koobi et al 1999); (3) the regional ICG (RIC), a
technology which is used by the NICaS (noninvasive cardiac system). In this technology,
which is the subject of this report, only two pairs of electrodes are used, performing best
when placed on one wrist and on the contralateral ankle (Cohen et al 1998, Cotter et al 2004,
Torre-Amione et al 2004).
Two comprehensive reviews of the literature on clinical experience in measuring the
cardiac output (CO) by TIC determined that in patients with cardiac conditions the TIC-CO
results are unreliable (Raaijmakers et al 1999, Handelsman 1991). According to Patterson
(1985) andWang et al (2001), a number of sources in the chest, such as the lungs, vena cava, and
systemic and pulmonary arterial vasculatures, generate systolic impedance reductions, while
the heart generates signals of increased impedance. In addition to thesemultifarious sources of
Z,4 variations in the electrical conductivities between the sources of impedance changes and
the TIC electrodes (Kim et al 1988, Kauppinen et al 1998), and between the various impedance
sources (Wtorek 2000) have been described. These model experimentations indicated that
the thoracic Z is not a reliable signal for calculation of the SV due to the multiple sources
of dZ/dt (Kim et al 1988, Wang and Patterson 1995, Kauppinen et al 1998, Wtorek 2000),
providing the explanations for the above-mentioned unsatisfactory clinical results obtained by
TIC (Raaijmakers et al 1999, Handelsman 1991).
In this report, an attempt is made to define the differences between the peripheral and
thoracic impedance signals, and based on this, to explain the differences in the performance
of RIC and TIC.
As we are capable of saving raw data from the wrist–ankle (peripheral) impedance
signals, we were able to use the peripheral impedance waveforms and base impedance values
to calculate stroke volumes, using various algorithms that have been associated with TIC
calculations. This enabled us to prove that (1) the performance of RIC is twice as accurate
as reported TIC results; (2) the reasons for this are as follows: (a) the impedance changes
which are yielded by the limb electrodes are more suitable than the impedance changes of
the thoracic electrodes for calculating the stroke volume and (b) the use of properly designed
coefficients improved the accuracy of the CO results by at least an additional 25%.
Methods
The data for this project were gathered from two patient series. In both, comparisons were made
between cardiac output results measured by the NICaS versus thermodilution. One series,
which was studied in hospital A, consisted of 30 patients who were studied immediately upon
arrival at the ICU following an open heart operation. In 11 (36%), despite the intravenous
administration of adrenalin, cardiac index (CI) was lower than 2.5 l min−1 m−2. The second
series included 13 cases of acute heart failure that were studied in hospital B. CI was lower
than 2.5 l min−1 m−2 in seven (54%), and in the combined group of 43 cases of the two
hospitals, it was lower than 2.5 l min−1 m−2 in 18 (43%).
The purpose of this study was to use peripheral impedance waveforms to calculate stroke
volume by means of four different ICG algorithms and to compare each of these SV values
with the thermodilution SV result.
Of the 55 and 31 studies conducted in hospitals A and B, respectively, raw data were
successfully retrieved from only the last 30 consecutive patients of hospital A and the last 13
4 In the ICGWB and RIC, where the impedance changes are depicted in the periphery, the impedance value is
automatically converted into the real parts (R0 and R) of the measured impedance signals (Lamberts et al 1984).

Predicting Future Cardiovascular Events

The Scientific World Journal
Volume 2013 (2013), Article ID 792693, 6 pages
http://dx.doi.org/10.1155/2013/792693

Clinical Study

Evaluation of Arterial Stiffness for Predicting Future Cardiovascular Events in Patients with ST Segment Elevation and Non-ST Segment Elevation Myocardial Infarction

Oguz Akkus,¹ Durmus Yildiray Sahin,² Abdi Bozkurt,³ Kamil Nas,⁴ Kazım Serhan Ozcan,¹ Miklós Illyés,⁵ Ferenc Molnár,⁶ Serafettin Demir,⁷ Mücahit Tüfenk,³ and Esmeray Acarturk³

¹Sanliurfa Siverek State Hospital, 63600 Sanliurfa, Turkey
²Department of Cardiology, Adana Numune Training and Research Hospital, Adana, Turkey
³Department of Cardiology, Faculty of Medicine, Cukurova University, Adana, Turkey
⁴Department of Radiology, Szent János Hospital, Budapest, Hungary
⁵Heart Institute, Faculty of Medicine, University of Pécs, Pécs, Hungary
⁶Department of Hydrodynamic Systems, Budapest University of Technology and Economics, Budapest, Hungary
⁷Department of Cardiology, Adana State Hospital, Adana, Turkey

Received 18 August 2013; Accepted 15 September 2013

Academic Editors: H. Kitabata and E. Skalidis

Copyright © 2013 Oguz Akkus et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Background. Arterial stiffness parameters in patients who experienced MACE after acute MI have not been studied sufficiently. We investigated arterial stiffness parameters in patients with ST segment elevation (STEMI) and non-ST segment elevation myocardial infarction (NSTEMI). Methods. Ninety-four patients with acute MI (45 STEMI and 49 NSTEMI) were included in the study. Arterial stiffness was assessed noninvasively by using TensioMed Arteriograph. Results. Arterial stiffness parameters were found to be higher in NSTEMI group but did not achieve statistical significance apart from pulse pressure . There was no significant difference at MACE rates between two groups. Pulse pressure and heart rate were also significantly higher in MACE observed group. Aortic pulse wave velocity (PWV), aortic augmentation index (AI), systolic area index (SAI), heart rate, and pulse pressure were higher; ejection fraction, the return time (RT), diastolic reflex area (DRA), and diastolic area index (DAI) were significantly lower in patients with major cardiovascular events. However, PWV, heart rate, and ejection fraction were independent indicators at development of MACE. Conclusions. Parameters of arterial stiffness and MACE rates were similar in patients with STEMI and NSTEMI in one year followup. The independent prognostic indicator aortic PWV may be an easy and reliable method for determining the risk of future events in patients hospitalized with acute MI.

1. Introduction

Acute myocardial infarction (AMI) continues a worldwide cause of mortality [1]. In-hospital and 6-month-mortality are approximately 5–7% versus 12-13%, respectively [2, 3]. Estimated risk of mortality for AMI is based on the clinical status of the patients [4]. Recent studies showed that conventional risk factors are inadequate for predicting cardiovascular (CV) mortality and morbidity. A novel risk factor called arterial stiffness, which is a defined reduction of the compliance of arterial wall, and relationship between coronary heart disease (CHD) have been demonstrated. Arterial stiffness results in faster reflection of the forward pulse wave from bifurcation points in peripheral vessels. As a result of new waveform, systolic blood pressure (SBP) increases, diastolic blood pressure (DBP) decreases, cardiac workload increases, and coronary perfusion falls down. It plays a major role in the determination of cardiovascular outcomes, and it is not inferior to the traditional risk factors to assess the future risk [5, 6]. Elevated arterial stiffness is associated with increased major adverse cardiovascular events (MACE) such as unstable angina, AMI, coronary revascularization, heart failure, stroke, and death [7]. Arterial stiffness parameters including mean arterial pressure (MAP), pulse pressure (PP), PWV (m/s), and augmentation index (AI) are directly proportional to the risk of MACE [8–10].

PWV is a susceptible diagnostic element, and it is also involved in risk stratification for subclinical organ damages [11]. Few studies regarding arterial stiffness demonstrated that PWV exhibits a close effect with coronary heart disease [5, 12, 13]. Whether arterial stiffness parameters are related to MACE after acute MI has not been studied sufficiently. The aim of our study was to compare arterial stiffness parameters in patients with ST segment elevation (STEMI) and non-ST segment elevation myocardial infarction (NSTEMI) and to validate its prognostic value.

2. Patients

Ninety-four patients with acute MI (72 men and 22 women, mean age 60,41 ± 11,17) were included in the study. There were 45 STEMI and 49 NSTEMI. Data of patients were analyzed within 24 hours after hospitalization. All patients received eligible treatment according to ESC guidelines. The choice of preparations was entrusted to the investigator. Hemodynamically compromised patients (Killip classifications II, III, and IV), patients with chronic atrial fibrillation and/or flutter, chronic renal failure, mild-severe valvular heart diseases and other chronic diseases were excluded. Our local ethics committee approved the study, and written informed consent was obtained from all participants. Patients were followed up for 12 months.

3. Diagnosis of Acute Myocardial Infarction

Diagnosis of AMI was based on symptoms, elevated cardiac markers, and electrocardiogram (ECG) changes. Patients with typical chest pain plus ECG changes indicative of an AMI (pathologic Q waves, at least 1 mm ST segment elevation in any 2 or more contiguous limb leads or new left bundle branch block, or new persistent ST segment and T wave changes diagnostic of a non-Q wave myocardial infarction) or a plasma level of cardiac troponin-T level above normal.

4. Laboratory Findings

Troponin T, creatine kinase-MB fraction (CK-MB), serum urea, creatinine, eGFR, and other hematological parameters were checked at the admission.

Risk factors, such as hypertension, hyperlipidemia, diabetes mellitus, cigarette smoking, and family history, were recorded. Hypertension was considered as SBP and DBP greater than 140 mmHg and 90 mmHg, respectively, using an antihypertensive medication. Diabetes mellitus, hyperlipidemia, and hypertriglyceridemia were defined as using antidiabetic drugs or fasting blood glucose over 126 mg/dL, as plasma low-density lipoprotein cholesterol (LDL-C) >130 mg/dL, using lipid-lowering drugs at the time of investigation, and as TG level >150 mg/dL, respectively, according to the Third Report of the National Cholesterol Education Program guidelines. First-degree relatives who are exposed to coronary artery disease (CAD) before the age for male is <55 and female <65 were considered as family history.

5. Pulse Waveform Analysis

Assessment of arterial stiffness was performed noninvasively with the commercially available TensioMed Arteriograph. We collected the oscillometric pulse waves from the patients. We measured the distance between the jugulum-symphysis (which is equal to the distance between the aortic root and the aortic bifurcation), and PWV was calculated. Pulse waves were recorded at suprasystolic pressure. The oscillation signs were identified from the cuff inflated at least >35 mmHg above the systolic blood pressure. In this state there was a complete brachial artery occlusion, and it functions as a membrane before the cuff. Pulse waves hit the membrane, and oscillometric waves were measured by the device and we could see the waveforms on the monitor. The AI was defined as the ratio of the difference between the second (P2 appearing because of the reflection of the first pulse wave) and first systolic peaks (P1 induced by the heart systole) to pulse pressure (PP), and it was expressed as a percentage of the ratio (AI = [P2 − P1]/PP × 100). SBP, DBP, PP, and heart rate and other hemodynamic parameters as return time (RT in sec.), diastolic reflection area (DRA), systolic area index (SAI %), and diastolic area index (DAI %) were measured noninvasively. DRA reflects the quality of the coronary arterial diastolic filling (SAI and DAI are the areas of systolic and diastolic portions under the pulse wave curve of a complete cardiac cycle, resp.). Hence, the bigger the DAI and DRA are, the better the coronary perfusion is. Furthermore, RT is the PWV time from the aortic root until the bifurcation and return, so this value is smaller as the aortic wall is stiffer.