Impedance Cardiography Device Research Articles

Effects of acute creatine supplementation on cardiac and vascular responses in older men; a randomized controlled trial

In the recent years creatine has been shown promising results in patients with neurodegenerative diseases, myopathies and dystrophies. Cardiovascular diseases could be another pathology that can benefit from creatine supplementation, considering the influence on the risk factors associated with the development of cardiovascular diseases including reduction in chronic inflammation, and improved control of hyperglycemia and dyslipidemia The aim of the present study was to investigate the impact of short-term creatine supplementation on cardiac and vascular health in older adults. Males between the ages of 55-80 were randomly assigned to three groups: creatine, placebo and control. Creatine or placebo was provided for 7-day supplementation, at a dose of 20g/day. Testing was performed at the same time of the day at baseline and on the eighth day. Vascular responses were assessed using an arterial pulse wave velocity equipment, while cardiac assessment was performed using an impedance cardiography device. The placebo group was older (71.1±8.2yr) compared to creatine (61.4±5.2yr) and control (62.5±7.1yr). Cardio-ankle vascular index improved just in the creatine group (8.7±0.5 to 8.2±0.5, p=0.03). While the upstroke time of the placebo and control groups did not change after 7 days, the creatine group had a nonsignificant reduction, 178.9±26.5ms to 158.4±28.6ms, p=0.07. Similar tendency was seen with the systolic blood pressures, while the placebo and control did not change, the creatine group showed nonsignificant improvement, especially on the right, 144.0±12.7mmHg to 136.1±13.4mmHg, p=0.08. All three groups had similar responses in stroke volume (p=0.61), contractility index (p=0.64) and ejection fraction (p=0.72). In older adults, acute creatine supplementation can positively affect vascular parameters of arterial stiffness and atherosclerosis. Creatine supplementation has the potential to serve as a potent adjuvant in the management of CVD for older adults. clinicaltrials.gov; ID: NCT05329480.

Contributors to Diminished Cardiorespiratory Fitness in Young Users of Electronic Cigarettes

Background: Cardiorespiratory fitness, an independent marker of cardiovascular health, represents the ability of respiratory, cardiovascular, and muscular systems to effciently deliver and utilize oxygen (O2) during exercise. Recently, reduced cardiorespiratory fitness was identified in young and healthy, regular users of electronic (e-) cigarettes; however, its limiting factors are not established. Thus, the purpose of this study was to investigate the contributors to impaired cardiorespiratory fitness in young regular users of e-cigarettes. Methods: An evaluation of hemodynamics, chronotropic response, and oxygen utilization during exercise was completed in nineteen regular users of e-cigarettes (EU, age: 23±3 yr; e-cigarette usage 4±2 yr.) and sixteen demographically matched non-users (NU, age: 23±3 yr.). Hemodynamics were accessed via a non-invasive signal morphology impedance cardiography device, while chronotropic responses were measured as changes in peak heart rate (HR). Oxygen extraction ratio (difference in arterial and venous O2 content) at baseline and peak exercise was also recorded. Fold changes from rest to peak exercise were assessed to provide insight into potential factors that limit cardiorespiratory fitness. Results: At peak exercise, users of e-cigarettes exhibited significantly higher chronotropic incompetence ( p=0.033) and lower ( p=0.047) peak HR than non-users, with no differences in other hemodynamic assessments. Significantly ( p=0.025) lower skeletal muscle O2 extraction (EU=51±11 vs. NU=61±10%) was also observed in users of e-cigarettes during peak exercise. Fold changes in chronotropic (HR; p=0.915) and hemodynamic (cardiac output; p=0.279) responses were similar between both groups, while significant ( p=0.048) differences in oxygen extraction ratio were identified between the users of e-cigarettes (0.5±0.3 fold change) and non-users (0.8±0.3 fold change). Conclusions: Results from our study demonstrate that young, regular users of e-cigarettes exhibit abnormal chronotropic responses and impaired skeletal muscle oxygen utilization during exercise when compared to non-users, suggesting reduced cardiovascular and muscle health. Overall, our findings contribute to the growing body of evidence that supports the negative effects of regular e-cigarette use on young individuals. Supported in part by a Rapid Response Project NIDA/FDA (PRM). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Rancang Bangun Alat Kardiografi Berbasis Impedansi Listrik (Electrical Impedance Cardiography)

Electrocardiography is a process or method to observe and record the activity of the heart by using a graph of electrical voltage versus time. A standard plan to achieve this is by measuring the bioelectric potential or bioimpedance of the heart organ. In this research, an electrical impedance cardiography device will be designed and tested. The process is carried out by using four electrodes that are attached at the neck and the diaphragm level of the body, an electric current with a specific value and frequency, then injected on a pair of electrodes, and the voltage will be measured on other pair of electrodes. The device testing process is carried out on subjects in good health and having no medical abnormality in a sitting and upright position. Impedance data will be measured and recorded at each time; the data that has been obtained will then be processed to determine the impedance graph Z and the first derivative of Z (dZ/dt). The number of heartbeats will also be calculated each time with another method, which is by using a stopwatch to compare the validity of the heart rate readings from the impedance cardiography device. The result demonstrated that the electrical impedance cardiography device that has been made could be used to illustrate heart rate graphs as a result of cardiovascular activity

Performance evaluation of a portable bioimpedance cardiac output monitor for measuring hemodynamic changes in athletes during a head-up tilt test.

Cardiac output (CO) monitoring is useful for sports performance training, but most methods are unsuitable as they are invasive or hinder performance. The performance of PhysioFlow (PF), a portable noninvasive transthoracic bioimpedance CO monitor, was evaluated and compared with a reference Doppler CO monitor, USCOM, using a head-up tilt (HUT) test. With ethics committee approval, 20 healthy well-trained athletes were subjected to HUT in a fixed order of 0°, 70°, 30°, and 0° for 3 min each. Simultaneous hemodynamic measurements using PF and USCOM were made 30 s after a change in HUT and analyzed using t tests, ANOVA, and mountain plots. Heart rate (HR) and stroke volume (SV) from both monitors changed according to physiological expectation of tilt, but PF measurements of SV were higher with a positive bias (PF vs. USCOM, 0°: 87.3 vs. 54.0 mL, P < 0.001; 70°: 76.5 vs. 39.5 mL, P < 0.001; 30°: 81.4 vs. 50.1 mL, P < 0.001; 0°: 88.3 vs. 57.1 mL, P < 0.001). Relative changes in SV (∆SV) after each tilt measured using PF were lower with a negative bias (PF vs. USCOM, 0° to 70°: -12.3% vs. -26.3%, P = 0.002; 70° to 30°: +6.4% vs. +31.2%, P < 0.001; 30° to 0°: +9.2% vs. +15.8%, P = 0.280). CO measurements using PF at 70° were erroneous. Compared with USCOM, PF overestimated SV measurements but underestimated the ∆SV between HUT. Accuracy of the PF deteriorated at 70°, implying a gravitational influence on its performance. These findings suggested that the suitability of PF for sports use is questionable.NEW & NOTEWORTHY The use of impedance cardiography to monitor physiological changes in sports is rarely reported. Using head-up tilt test, we evaluated a portable noninvasive impedance cardiography device (PhysioFlow) by comparing it with a reference Doppler monitor (USCOM). Accuracy in tracking hemodynamic changes deteriorated with higher tilt, implying a gravitational influence on its performance. Stroke volume measurements were overestimated, but the changes were underestimated. Despite its convenient physical features, the suitability of PhysioFlow for sports use is questionable.

Acute Soy Supplementation Improves 20-km Time Trial Performance, Power, and Speed.

Isoflavones, a chemical class of phytoestrogens found in soybeans and soy products, may have biological functions similar to estradiol. After binding with ERβ or perhaps independently of estrogen receptors, isoflavones may augment vascular endothelial relaxation, contributing to improved limb blood flow. To determine if acute fermented soy extract supplementation influences 20-km time trial cycling performance and cardiac hemodynamics compared with a placebo. Subjects included 25 cyclists and triathletes (31 ± 8 yr, V˙O2peak: 55.1 ± 8.4 mL·kg·min). Each subject completed a V˙O2peak assessment, familiarization, and two 20-km time trials in randomized order after ingestion of a fermented soy extract supplement or placebo. The fermented soy extract consisted of 30 g powdered supplement in 16 fl. ounces of water. The placebo contained the same quantities of organic cocoa powder and water. Each trial consisted of 60 min of rest, 30 min at 55% Wpeak, and a self-paced 20-km time trial. Soy supplementation elicited a faster time to 20-km completion (-0.22 ± 0.51 min; -13 s), lower average HR (-5 ± 7 bpm), and significantly greater power (7 ± 3 W) and speed (0.42 ± 0.16 km·h) during the last 5 km of the time trial compared with placebo. Analysis of the results by relative fitness level (<57 vs ≥ 57 mL⋅kg⋅min) indicated that those with a higher level of fitness reaped the largest performance improvement alongside a reduced HR (-5 ± 7 bpm). Ingestion of a fermented soy extract supplement improved sprint-distance performance through improvements in both power and speed. For those with great aerobic fitness, soy supplementation may help to decrease cardiac demand alongside performance improvement.

Usefulness of stroke volume monitoring during upright ramp incremental cycle exercise in young patients with Fontan circulation

BackgroundAerobic capacity (VO2 max) of patients with Fontan circulation (FC) is lowest within patients with congenital heart disease. The reasons have not been completely elucidated. MethodsTwenty five young patients with non-failing FC underwent a cardiopulmonary test during an upright ramp cycling. By using a signal morphology impedance cardiography device (physioflow®), stroke volume (SV) was evaluated along with effort. The results were compared with paired healthy controls. ResultsFC patients had lower VO2 max (24 vs 32ml/Kg/min) and maximal cardiac index (CI) (6.4 vs 9.9l/min/m2) than controls, due to impaired maximal SV (42 vs 54ml/m2) and maximal Heart Rate (HR) (154 vs 184/min) (p<0.001). No correlation between SV and HR at peak was found. At ventilatory threshold, SV continued to rise in a part of FC patients. Other FC patients showed an almost a “plateau” as in controls. The more maximal CI was impaired, the more was maximal arterio-venous difference (r=−0.6, p=0.001). Compared to controls, stroke work was lower in FC patients (p<0.01) even though maximal vascular resistance was higher in them (p<0.001). ConclusionImpaired SV and chronotropic incompetence are both independently responsible for impaired CI at peak. The increase in arteriovenous difference appeared to be an adaptive response. As the stroke work was low among FC patients, high systemic vascular resistance does not appear to be the cause of SV impairment but rather a consequence. SV monitoring at effort evidences heterogeneous SV profiles among FC patients that could be considered for the management of patients.

The Impact of Obstructive Sleep Apnea on Cardiovascular Hemodynamics During Steady-state Exercise

Obstructive Sleep Apnea (OSA) is a disorder characterized by repetitive partial and/or complete airway collapse of the upper airway. This disorder significantly increases the risk for Cardiovascular Disease (CVD) and heart failure. The repetitive respiratory effort against a closed airway has been shown to result altered hemodynamic variables, suggesting cardiovascular remodeling. To date, these findings have only been shown at rest. Whether these alterations manifest during exercise has not been examined. PURPOSE: To determine the effect that OSA has on hemodynamic variables during steady-state exercise compared to non-OSA controls. METHODS: Subjects were classified as OSA (N=21) or controls (N=21) based on an overnight, at-home screening device. Cardiovascular hemodynamic variables were assessed using an non-invasive, impedance cardiography device at rest and during a submaximal treadmill exercise trial. Subjects exercised for 5 minutes at 70% of predicted VO2 Reserve (VO2R). Hemodynamic variables included cardiac output, stroke volume, ejection fraction, systemic vascular resistance, contractility index (CTi) and end-diastolic volume (EDV). RESULTS: Control subjects were significantly younger (28.1 ± 11.5 vs. 41.8 ± 12.8) and had a lower BMI (28.5 ± 3.2 vs. 31.6 ± 5.3) than the OSA group. After adjusting for age and BMI, no hemodynamic variables differed at rest between groups. With exercise, however, OSA subjects had a lower CTi (268.9 ± 76.2 vs. 407.5 ± 142.7, P < 0.05) and a higher EDV (156.8 ± 32.9 vs. 122.6 ± 23.8, P = 0.03). No other hemodynamic variables differed with exercise. CONCLUSIONS: Results suggest that the presence of OSA results in alterations in cardiovascular exercise hemodynamics, suggestive of remodeling of the myocardium. The CTi represents the maximal velocity of ejected blood flow, a surrogate for contractility, which was attenuated in the OSA group. This decreased contractility likely contributed to the decreased EDV also observed. These findings suggest that OSA may impact exercise capacity and contribute to the the increased risk for CVD and heart failure previously established.

A Novel Noninvasive Device to Assess Sympathetic Nervous System Function in Patients With Heart Failure

Heart failure is a complex syndrome associated with sympathetic nervous system and renin-angiotensin-aldosterone system hyperactivity. Sympathoinhibition and downregulation of sympathetic activity using medications and exercise training improve outcomes in patients with heart failure. Impedance cardiography provides data on hemodynamic and autonomic function that may assist with safe medication, exercise monitoring, and titration. The purpose of this pilot study was to evaluate the sensitivity of the Vrije Universiteit Ambulatory Monitoring System (VU-AMS) version 5fs to detect hemodynamic and sympathetic nervous system changes associated with postural shift in persons with heart failure with reduced ejection fraction. In this descriptive study, participants (N = 28) were recruited from an outpatient device clinic at a tertiary care hospital in Ontario, Canada. They completed a sit-to-stand posture protocol wearing an ambulatory blood pressure (ABP) and a noninvasive VU-AMS version 5fs impedance cardiography system. Most (n = 18, 64%) participants were eliminated from the final analyses in this sample because of difficulty in Q-onset and B-point identification in peculiar electrocardiogram and impedance cardiogram waveforms. The remaining participants (n = 10) had a mean age of 69 years (SD = 10 years) and responses to a sit-to-stand posture protocol that included a 5% increase in heart rate (p = .001), an 18% decrease in stroke volume (p = .01), and an 8% decrease in left ventricular ejection time (p = .01). Participants had an increased preejection period (11%, p = .01), a drop in cardiac output of 13% (p = .02), and a reduced mean arterial pressure of approximately 4% (p = .09) with standing. Although the VU-AMS version 5fs system detected anticipated hemodynamic and sympathetic nervous system changes to postural shift in participants (n = 10), the elimination of 64% (n = 18) of the sample because of scoring difficulties limits the use of this impedance cardiography device using standard scoring algorithms in persons with heart failure with reduced ejection fraction.

Lithotomy versus jack-knife position on haemodynamic parameters assessed by impedance cardiography during anorectal surgery under low dose spinal anaesthesia: a randomized controlled trial.

BackgroundAlthough the prone position providing better exposure for anorectal surgery is required it can cause a reduction of cardiac output and cardiac index. The goal was to compare haemodynamic changes assessed by impedance cardiography during anorectal surgery under low-dose spinal anaesthesia in lithotomy and jack-knife position.MethodsThe prospective randomized controlled study included 104, ASA I-II adult patients admitted for elective minor anorectal surgery, assigned to be performed in lithotomy (groupL, n = 52) or jack-knife position (groupJ, n = 52). After arrival to operating room the standard monitoring, impedance cardiography device was connected to the patient, and the following variables were recorded: cardiac output, cardiac index, systemic vascular resistance, stroke index at times of arrival to operating room, placement for, start and end of surgery and placement to bed. Spinal block was made in the sitting position with 4 mg of 0.5% hyperbaric bupivacaine and 10 μg of Fentanyl injected over 2 min. Comparison was based on haemodynamic changes between and inside groups over time. Student’s t, chi square tests were used for statistical analysis with p < 0.05 regarded as statistically significant.ResultsThe reduction of cardiac output was statistically significant after placement of the patient into the prone position: from baseline 7.4+/−1.6 to 4.9+/−1.2 after placement for and 4.7+/−1.2 at the start and end of surgery (mean +/−SD l/min). The difference of cardiac output between groups was 2.0 l/min after positioning for and the start of surgery and 1.5 l/min at the end of surgery (p < 0.05). Mean cardiac index reduced from baseline 3.9+/−0.8 to 2.6+/−0.7 and 2.4+/−0.6 (mean+/−SD l/min/m2) in groupJ and between groups: by 1.0 l/min/m2 after placement for, 1.1 at the start and 0.8 at the end of surgery (p < 0.05). Systemic vascular resistance increased from baseline 1080+/−338 to 1483+/−479 after placement for, 1523+/−481 at the start and 1525+/−545 at the end of surgery in groupJ (mean+/−SD dynes/sec/cm−5, p < 0.05).ConclusionsAccording to impedance cardiography, jack-knife position after low-dose spinal anaesthesia produces transitory, but statistically significant reduction of cardiac output and cardiac index with increase of systemic vascular resistance, compared to insignificant changes in lithotomy position.Trial registrationClinical Trials NCT02115178.

Development of a wearable multi-frequency impedance cardiography device

Cardiovascular diseases as well as pulmonary oedema can be early diagnosed using vital signs and thoracic bio-impedance. By recording the electrocardiogram (ECG) and the impedance cardiogram (ICG), vital parameters are captured continuously. The aim of this study is the continuous monitoring of ECG and multi-frequency ICG by a mobile system. A mobile measuring system, based on ‘low-power’ ECG, ICG and an included radio transmission is described. Due to the high component integration, a board size of only 6.5 cm × 5 cm could be realized. The measured data can be transmitted via Bluetooth and visualized on a portable monitor. By using energy-efficient hardware, the system can operate for up to 18 hs with a 3 V battery, continuously sending data via Bluetooth. Longer operating times can be realized by decreased transfer rates. The relative error of the impedance measurement was less than 1%. The ECG and ICG measurements allow an approximate calculation of the heart stroke volume. The ECG and the measured impedance showed a high correlation to commercial devices (r = 0.83, p < 0.05). In addition to commercial devices, the developed system allows a multi-frequency measurement of the thoracic impedance between 5–150 kHz.

Association of thyrotropin with arterial pulse wave velocity in young adults: The Cardiovascular Risk in Young Finns Study

Objective. Limited data are available regarding the relationship of thyrotropin (TSH) and arterial pulse wave velocity (PWV) at population level. Therefore, we conducted the present study to determine whether TSH is related to PWV assessed in young adulthood. Methods. The study population consisted of 1598 Finnish white young adults (aged 30–45 years, 47.4% males) who had TSH, traditional cardiovascular risk factors, and PWV measured in 2007. PWV measurements were performed using a whole-body impedance cardiography device. Results. In bivariate association analyses, TSH level was significantly associated with body mass index (BMI), smoking, diastolic blood pressure, triglyceride and insulin levels (p < 0.001). In multivariable regression model, TSH (β = 0.055, p = 0.015) was associated with PWV when adjusted with age (β = 0.295, p < 0.001) and sex (β = 0.345, p < 0.001). The association of TSH with PWV was however diluted to non-significant after further adjustment with traditional risk factors (β = 0.027, p = 0.218 for TSH). Conclusion. Serum TSH was associated with PWV on population level when adjusted with age and sex. This association was diluted when cardiovascular risk factors were added in the model, suggesting that the association of thyroid hormone on arterial stiffening is not independent of changes in the traditional risk factor levels.

A portable device to assess underwater changes of cardio dynamic variables by impedance cardiography

Data concerning heart rate (HR), stroke volume (SV), and cardiac output (CO) during dynamic apnoea (DA) were collected from 10 healthy male, elite divers by means of an impedance cardiograph adapted to the underwater environment (C. O. Re., from 2C Technologies Inc, Italy). Three trials were performed by the divers in a 3-m-deep pool with a water temperature of 25°C: 3-minute head-out immersion during normal breathing (A), till exhaustion immersed at the surface (B) and at 3m depth (C). Both B and C conditions did not led to changes in HR, SV and CO compared to A. Data indicate that typical diving response consisting in a reduction of HR, SV and CO was not present during DA, probably due to sympathetic activation induced by exercise during DA, which partially obscured the effects of the diving response. Moreover, this study highlights the innovative role of our portable, impedance cardiography device, i.e. the C. O. Re., in easily assessing cardiodynamic changes in subjects engaged in exercise schedules including phases of underwater, dynamic apnoea.

OS095. Impedance cardiography: A straightforward and reliable tool to evaluate differences of cardiac reflex response between normal pregnancy and pre-eclampsia

Reflex responses of cardiac cycle time intervals (CCTI) can be measured by echocardiography, and are reported to differ between uneventful pregnancy (UP) and pre-eclampsia (PE). It is unknown whether impedance cardiography (ICG) is a useful method to measure CCTI during pregnancy. ICG measurements of CCTI before and after orthostatic challenge are evaluated in UP and in the clinical phase of PE. Examinations were performed twice in 16 UP (30-36 weeks), and once in 30 early PE (EPE, <34 weeks) and in 32 late PE (LPE, ⩾34 weeks). A 3rd generation ICG device using a 4 electrode arrangement (NICCOMO, Medis, Germany) was used to measure CCTI in supine position and after moving to upright position. The pre-ejection period (PEP) is the time-interval between ventricular depolarisation and start of aortic flow. The left ventricular ejection time (LVET) is the time-interval between opening and closing of the aortic valve. Diastolic time (DT) is heart period duration - (PEP+LVET). Orthostatic-induced changes from supine to upright position (cardiac reflex response or CRR) were evaluated using One-sample Wilcoxon Signed Rank Tests. All CRRs in EPE and LPE were compared to UP using Mann-Whitney U tests. Data are represented as medians (interquartile ranges). Maternal age was comparable between all groups [29 (26-32) years; p⩾0.47]. Gestational age was comparable between both early [31 (28-32) vs 31 (27-33) weeks] and late [37 (36-39) vs 38 (36-39) weeks] third trimester UP and PE [p⩾0.38]. Pre-gestational BMI was higher in EPE compared to UP [26 (24-32) vs 23 (21-24); p<0.01]. This was not true for LPE [25 (23-28); p=0.06]. Birth weight percentiles were lower in both EPE and LPE compared to UP [UP: 44 (38-78), EPE: 18 (5-28), LPE: 31 (18-59); p<0.05], and also lower in EPE compared to LPE [p=0.03]. CRRs within each group are shown in Table 1. The CRRs of PEP were significantly different between UP and both EPE and LPE [p⩽0.01], due to orthostatic-induced increase in PE but not in UP . Our study confirms that orthostasis does not change PEP in UP but induces a significant increase of PEP in PE. The increased reflex-induced duration of isovolumetric contraction time can be explained by a decreased left ventricular performance in the clinical phase of PE as compared to UP. ICG turns out to be a straightforward and useful method to evaluate these hemodynamic features.

Bioimpedance Cardiac Output Measurement in Hemodialysis Patients

To the Editor: Measuring cardiac output (CO) in hemodialysis (HD) patients is of potentially great value for studying the pathophysiology of intradialytic hypotension. However, only one device currently available—the Transonic monitor (TRS; Transonic Systems, Ithaca, NY)—has gone through an appropriate validation. The TRS is generally regarded as the reference method for intradialytic CO measurements. Unfortunately, being an indicator dilution method, it cannot give continuous readings, and its use is restricted to patients with AV fistulas. Kitzler et al1 performed a validation study on 12 patients, examining a novel impedance cardiography (ICG) device [Task Force monitor (TFM), CN Systems, Graz, Austria] with the TRS as the reference method. The authors reported good agreement between the two methods (r2 = 0.64, SD 0.6 L/min on Bland-Altman analysis). However, their approach was to measure CO simultaneously with both methods 3 to 7 times during each session and then compare the 12 overall session mean values from each method. Thus, their publication neither revealed the precision of individual CO measurements with the TFM nor, most importantly, whether intradialytic CO trends are reliably tracked with the TFM. We addressed these last questions in a validation study on another ICG device, the BioZ (BZ; SonoSite Inc., Washington,). Twelve maintenance HD patients with AV fistulas were studied during one session each; the study was approved by the regional ethics committee and all participants gave informed consent. Demographic data of the participants are listed in Table 1.Table 1: Demographic Data of the ParticipantsA simultaneous CO measurement was performed with the BZ and the TRS in the first hour of the dialysis session and repeated in the last hour. The measurements of each method are presented in Table 2. Bland-Altman analysis revealed systematic underestimation of CO by the BZ (bias −15.9%, SD 26.4%, Figure 1). Regression analysis of difference versus average for proportional bias was nonsignificant (Figure 1).Table 2: Intradialytic CO Measurements with Each MethodFigure 1.: Bland-Altman plot of paired measurements, n = 24. The difference between measurements is presented as the relative (percentage) difference from the average. The dotted lines represent the limits of agreement. BZ, BioZ; TRS, Transonic.Regression analysis of relative changes showed no correlation between pairs (r2 = 0.04, Figure 2). A concordance analysis2 with the cutoff set at 15% change yielded a concordance rate of 20% (1/5 pairs).Figure 2.: Correlation plot of the measured relative (percentage) intradialytic change in cardiac output, n = 12. CO, cardiac output; BZ, BioZ; TRS, Transonic.Our results raise serious concerns about use of the BZ for intradialytic hemodynamic assessment. Although the BZ and other ICG monitors have in fact been used for this purpose,3,4 to our knowledge, the method has in this setting only been validated against transthoracic echocardiography-derived CO5—a technique whose operator-dependency and variability interferes with its suitability as reference method—and in the aforementioned study1 with its relative obscurity of data. In conclusion, we find that use of ICG for research in dialysis hemodynamics remains controversial until rigorous validation studies support its reliability. Joakim Cordtz Soeren D. Ladefoged Department of Nephrology Copenhagen University Hospital Copenhagen, Denmark

Arterial pulse wave velocity in relation to carotid intima-media thickness, brachial flow-mediated dilation and carotid artery distensibility: The Cardiovascular Risk in Young Finns Study and the Health 2000 Survey

Objective Increased arterial pulse wave velocity (PWV) is a strong predictor of cardiovascular events and mortality. The data regarding the relationships between PWV and other indices of vascular damage is limited and partly controversial. We conducted the present study to examine PWV in relation to non-invasive measures of early atherosclerosis (brachial flow-mediated dilation [FMD], carotid intima-media thickness [IMT]) and local arterial stiffness (carotid artery distensibility [Cdist]). Methods The study population consisted of 1754 young adults (aged 30–45 years, 45.5% males) participating in the Cardiovascular Risk in Young Finns Study (YFS), and of 336 older adults (aged 46–76 years, 43.2% males) participating in the Health 2000 Survey. FMD was measured only in the YFS cohort. FMD, IMT and Cdist were assessed by ultrasound, and PWV was measured using the whole-body impedance cardiography device. Results In young adults, FMD and IMT were not associated with PWV independently of cardiovascular risk factors. Moreover, FMD status was not found to modulate the association between cardiovascular risk factors and PWV. In older adults, PWV and IMT were directly and independently associated ( β = 1.233, p = 0.019). In both cohorts, PWV was inversely related with Cdist, and this relation remained significant ( p < 0.04) in models adjusted for cardiovascular risk factors. Conclusions The current findings suggest that PWV reflects a different aspect of vascular damage than FMD or IMT in young adults, whereas in older adults the information provided by PWV and IMT may be, to some extent, similar as regards subclinical vascular damage. The present observations also suggest that PWV and Cdist represent, at least in part, a similar adverse vascular wall process.

Lifetime Fruit and Vegetable Consumption and Arterial Pulse Wave Velocity in Adulthood

Background— The relationships between childhood lifestyle risk factors and adulthood pulse wave velocity (PWV) have not been reported. We studied whether childhood and adulthood lifestyle risk factors are associated with PWV assessed in adulthood. Methods and Results— The study cohort comprised 1622 subjects of the Cardiovascular Risk in Young Finns Study followed up for 27 years since baseline (1980; aged 3 to 18 years) with lifestyle risk factor data available since childhood. Arterial PWV was measured in 2007 by whole-body impedance cardiography device. Vegetable consumption in childhood was inversely associated with adulthood PWV (β=−0.06, P =0.02), and this association remained significant (β=−0.07, P =0.004) when adjusted for traditional risk factors (high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, triglycerides, systolic blood pressure, body mass index, and smoking). Vegetable consumption was also an independent predictor of PWV in adulthood when adjusted for lifestyle or traditional risk factors (β=−0.08, P =0.002 and β=−0.07, P =0.0007, respectively). Persistently high consumption of both fruits and vegetables from childhood to adulthood was associated with lower PWV compared with persistently low consumption ( P =0.03 for both). The number of lifestyle risk factors (the lowest quintile for vegetable consumption, fruit consumption, physical activity, and smoking) in childhood was directly associated with PWV in adulthood ( P =0.001). This association remained significant when adjusted for the number of lifestyle risk factors in adulthood ( P =0.003). Conclusions— These findings suggest that lifetime lifestyle risk factors, with low consumption of fruits and vegetables in particular, are related to arterial stiffness in young adulthood.

Apolipoprotein B is related to arterial pulse wave velocity in young adults: The Cardiovascular Risk in Young Finns Study

ObjectiveLimited data are available regarding the relationship of apolipoproteins B (ApoB) and A-1 (ApoA-1) with arterial stiffness. We conducted the present study to determine whether adulthood ApoB and ApoA-1 are related to arterial pulse wave velocity (PWV). Moreover, we examined whether ApoB and ApoA-1 measured in young adulthood are predictive of PWV assessed 6 years later. MethodsThe study population consisted of 1618 apparently healthy Finnish young adults (aged 30–45 years, 44.9% males) whose apolipoproteins, other cardiovascular risk factors and PWV were measured in 2007. In a sub-sample population, apolipoproteins and other cardiovascular risk factors had also been measured in 2001 (n=1264). PWV measurements were performed using a whole-body impedance cardiography device. ResultsApoB (p<0.001) and the ApoB/ApoA-1 ratio (p<0.001) were directly associated with PWV. ApoB and the ApoB/ApoA-1 ratio measured in young adulthood were also predictive of PWV measured 6 later (p<0.001 for both). These relations remained significant (p<0.006) in models adjusted for non-lipid risk factors. The areas under the receiver-operating characteristic (ROC) curves (AUC) were similar for ApoB and non-HDL cholesterol (2001: p for AUC comparison=0.15; 2007: p for AUC comparison=0.07) in detecting subjects with increased PWV (PWV≥90th percentile). ConclusionThe present study suggests that elevation of ApoB or non-HDL cholesterol is associated with increased arterial stiffness in young adults.

Systemic hemodynamics in relation to glucose tolerance: the Health 2000 Survey

The influence of impaired glucose metabolism—that is, impaired fasting glucose, impaired glucose tolerance (IGT), and type 2 diabetes mellitus diabetes (DM2)—on systemic hemodynamics is largely unknown. Therefore, we investigated the associations of glucose metabolism disturbances with stroke index (SI), cardiac index, systemic vascular resistance index (SVRI), arterial pulse wave velocity (PWV), and heart rate among Finnish adults (N = 389; mean age, 58.3 ± 7.9 years) participating in the Health 2000 Survey. Systemic hemodynamic parameters were measured using the whole-body impedance cardiography device, and an oral glucose tolerance test (OGTT) was performed to evaluate glucose tolerance status. We found a decreasing trend for SI and increasing trends for SVRI and PWV according to the worsening of glucose tolerance ( P for trend < .003 for all). In pairwise comparisons, SI was lower in the impaired fasting glucose group ( P = .041) and the IGT group ( P < .001) as compared with the normal glucose tolerance (NGT) group. Systemic vascular resistance index was higher in the IGT group ( P = .045) and the DM2 group ( P = .043) than in the NGT group. Subjects with IGT or DM2 had higher arterial PWV (10.7 ± 0.2 m/s, P < .001 and 11.7 ± 0.5 m/s, P = .001, respectively) than subjects with NGT (9.5 ± 0.1 m/s). Moreover, 2-hour glucose in OGTT was an independent determinant of SVRI and PWV ( P < .001 and P = .005, respectively) in multivariable linear regression models. In conclusion, the present study demonstrates that glucose intolerance, even without DM2, associates with several adverse changes in systemic hemodynamics and that 2-hour glucose in OGTT is an independent determinant of SVRI and PWV. These findings support the systematic evaluation of glucose tolerance status in the estimation of cardiovascular risk among the middle-aged population.

DURATION OF THE EFFECTS OF A SINGLE INTRAPROSTATIC INJECTION OF BOTULINUM TOXIN TYPE A IN FRAIL ELDERLY PATIENTS WITH BENIGN PROSTATIC ENLARGEMENT

Aerobic capacity (VO2 max) of patients with Fontan circulation (FC) is lowest within patients with congenital heart disease. The reasons have not been completely elucidated.Twenty five young patients with non-failing FC underwent a cardiopulmonary test during an upright ramp cycling. By using a signal morphology impedance cardiography device (physioflow®), stroke volume (SV) was evaluated along with effort. The results were compared with paired healthy controls.FC patients had lower VO2 max (24 vs 32 ml/Kg/min) and maximal cardiac index (CI) (6.4 vs 9.9 l/min/m2) than controls, due to impaired maximal SV (42 vs 54 ml/m2) and maximal Heart Rate (HR) (154 vs 184/min) (p < 0.001). No correlation between SV and HR at peak was found. At ventilatory threshold, SV continued to rise in a part of FC patients. Other FC patients showed an almost a “plateau” as in controls. The more maximal CI was impaired, the more was maximal arterio-venous difference (r = − 0.6, p = 0.001). Compared to controls, stroke work was lower in FC patients (p < 0.01) even though maximal vascular resistance was higher in them (p < 0.001).Impaired SV and chronotropic incompetence are both independently responsible for impaired CI at peak. The increase in arteriovenous difference appeared to be an adaptive response. As the stroke work was low among FC patients, high systemic vascular resistance does not appear to be the cause of SV impairment but rather a consequence. SV monitoring at effort evidences heterogeneous SV profiles among FC patients that could be considered for the management of patients.

Impedance cardiography in the estimation of hemodynamic and fluid status of coma patients during continuous venovenous hemodiafiltration

Most ICU patients on continuous venovenous hemodiafiltration (CVVHDF) are in multisystem failure and require extensive monitoring [1]. Impedance cardiography (ICG) technology provides a measurement of fluid status using the thoracic fluid content (TFC), along with cardiac output (CO), cardiac index (CI) and systemic vascular resistance index (SVRI). NICCOMO® (Medis, Germany), a noninvasive ICG device that provides trustworthy measures, could be a complementary monitor for CVVHDF, supporting fluid balance and helping avoid hemodynamic instability [2].