To Consejo Nacional de Ciencia y Tecnolog&#237;a (CONACyT) that sponsored the scholarship CVU 1004551 for Dulce Mar&#237;a Navarrete de la O during her MSc degree.

The Institutional Research Ethics Committee from Centro M&#233;dico Nacional &#34;20 de Noviembre&#34;, ISSSTE, approved this protocol (ID 383.2019). All enrolled patients signed written informed consent.
1. Before bioelectrical impedance analysis (BIA) measurement
NOTE: The BIA protocol procedure is measured using a single-frequency bioelectrical impedance device (Table of Materials). This device provides two values (resistance and reactance) at 50 kHz. Also, the BIA protocol described here is specific according to the single-frequency bioelectrical impedance device used.
<ol>
	<li>Standardization and technical requirements of the device
	<ol>
		<li>Test the correct calibration of the device using the test resistor (500 &#937;) provided by the manufacturer. Acceptable values for resistance and reactance are 495.0 to 505.0 &#937; and -3.0 to 3.0 &#937;, respectively. Ensure that the skin electrodes correspond to the same manufacturer&#39;s brand and that the device is not connected to the electric current.</li>
		<li>Clean and disinfect the device and the leads with hydrogen peroxide solution-based water (1:4). Dampen a clean wiping cloth with the solution and rub gently along the wires and the outside of the device case.</li>
	</ol>
	</li>
	<li>Patient analysis and preparation for the test (pre-test) 
	NOTE: Patients diagnosed with IHD, male or female, and aged &#62;18, were included. As well as patients with controlled comorbidities such as systemic arterial hypertension, dyslipidemia, and type 2 diabetes mellitus were also included. The mean weight and height were 70 kg and 160 cm, respectively. In addition, patients were excluded if they presented any of the following characteristics: active smoking or smoking cessation &#60;6 months, myocardial infarction or stroke in the last 6 months, anemia, electrolyte imbalance, and chronic terminal diseases such as renal or hepatic failure.
	<ol>
		<li>Inform the patient regarding fasting for at least 2-3 h before the measurement.</li>
		<li>Explain the procedure to the patient.</li>
		<li>Collect gender, age, weight (in kg), and height (in cm) information. For measuring height and weight, use a digital portable precision scale, and a portable precision stadiometer, respectively (Table of Materials), and perform the measurements based on the standard method described by Lohman et al.17.</li>
		<li>Instruct the patient to take out any metal objects he/she is wearing (watches, rings, bracelets, necklaces, or any other) to avoid interference with the measurements. Ask the patient to remove their shoes and stocks.</li>
		<li>Place the patient in a supine position on a stretcher bed. Ensure that arms and legs maintain an angular separation of 30&#176; to 45&#176; and the palms of the hands face upwards. If the thighs are too big, use a clean towel/sheet to create a non-conductive barrier and separate them. Also, make sure the material of the stretcher bed is not metal conductive. 
		NOTE: To achieve stable fluid distribution after the patient acquires a supine position, recommended lying down for at least 5 min before BIA measurements.</li>
		<li>Clean the area before connecting skin electrodes using a pad soaked with 70% ethyl alcohol.</li>
		<li>Place four skin electrodes as described below. Place all skin electrodes according to manufacturer recommendations and with a distance between them of at least 5 to 10 cm to avoid electrode-electrode interaction.
		<ol>
			<li>First, place proximal electrodes on the hands as follows: locate one electrode on the wrist, just between the lunate-scaphoid carpal joint and ulna-radius joint. Then, locate another electrode at the middle finger, just behind the metacarpophalangeal joint.</li>
			<li>Then, place the distal electrodes on the feet, as follows: locate one electrode on the ankle, at the joint between the internal and external malleoli and astragalus. Then, locate another electrode between the metatarsophalangeal joints of the third finger.</li>
		</ol>
		</li>
	</ol>
	</li>
</ol>
2. BIA measurements
<ol>
	<li>Connect the circular outlet of the leads to the back of the device.</li>
	<li>First, connect the hand guide leads (proximal)- the red clip on the wrist, and the black clip on the middle finger, then connect the foot guide (distal) - the red clip on the ankle and the black clip on the third finger. Verify that all clips are placed on the skin electrode&#180;s edge.</li>
	<li>Instruct the patient not to move while the measurement is performed.</li>
	<li>Turn on the device by pressing the ON button. Observe the values on the screen immediately and wait for 30 s to 60 s for resistance and reactance data to stabilize, then register those values. Turn off the device by pressing the OFF button.</li>
	<li>Once the measurement is done, remove the red and black clips for the hand and the foot, then remove the skin electrodes carefully and discard them.</li>
</ol>
3. Analysis and evaluation of hydration status by BIVA
NOTE: Before starting the BIA analysis, it is necessary to download the BIVA software (Table of Materials). Note that the BIVA software is a spreadsheet with data from different populations and reference values of resistance and reactance arranged by sex18.
<ol>
	<li>The BIVA software contains the following seven sheets: guide, reference populations, point graph, path, subjects, z-score, and z-graph. Click the Reference Population sheet and select the complete line according to the population to be evaluated. This methodology uses rows 9 and 10 (Mexican population)19.</li>
	<li>Copy the selected data and paste them into the second row.</li>
	<li>Click the Subjects sheet and fill manually the following information located in the second row- Column 1: Patient ID; Column 2: Seq, should always be 1; Column 3 and Column 4: indicate the Surname and Name, respectively; Column 5: Sex, assign F if female or M if male; Column 6 and Column 7: add values of resistance and reactance (previously registered), respectively; Column 8: Height, indicate value in cm; Column 9: Weight, indicate the value in kg; Column 10: Popl Code, indicate a value between 1 to 13 that appears in the first column of the reference population sheet to choose the population to be evaluated; Column 11: Group Code, add a value between 1 to 10 to select the patient to be evaluated; Column 12: Age, indicate the age in years.</li>
	<li>Click the Complement option in the main menu and click Calculate to obtain the resistance and reactance values adjusted by height (columns 13 and 14).</li>
	<li>Click the Point Graph sheet, and the R/H-Xc/H graph will be displayed for females or males. This graph contains the 50%, 75%, and 95% percentile tolerance ellipses adjusted by specific reference populations (Figure 1).</li>
	<li>When a dialog box named select groups is displayed, select the Group Option according to the last number indicated in the subject&#39;s sheet - Column 11. Add the value previously registered at the group code and click OK. A vector will be plotted showing the shape characteristics.</li>
	<li>Interpret the hydration status from the plot as follows: a vector between 50% and 95% percentiles tolerance ellipses indicates euhydration, whereas a vector outside the upper pole of 95% tolerance ellipse indicates hypohydration and a vector outside in the lower pole of 95% tolerance ellipse indicates hyperhydration.</li>
</ol>
4. Before starting the exercise stress test (EST) protocol
NOTE: The exercise stress test (EST) protocol20,21 is measured using a specialized medical treadmill (Table of Materials). EST is carried out according to the modified Bruce ramp protocol20,21 and supervised by an experienced cardiologist.&#160;
<ol>
	<li>Patient analysis and preparation
	<ol>
		<li>Ensure the patient complies with the following characteristics before the test: avoid any strenuous physical activity at least 1 day before the test, and fast the patient at least 4 h before the test. Ask the patient to wear comfortable clothing for the test.</li>
		<li>Explain to the patient the EST protocol and register the gender, age, weight (in kg), and height (in cm). Enter the gender, age, weight, and height data into the EST system to automatically estimate the METS, VO2, and HR/O2 values during the test.</li>
		<li>Ask the patient about any physical disability (e.g., joint or chest pain, dyspnea, etc.) before EST. Observe the patient&#180;s gait and ensure it does not present a walking disorder.</li>
	</ol>
	</li>
	<li>EST devices connection to patient and system calibration
	<ol>
		<li>Select and place a size-fit EST mask, then gently fix it to the patient&#180;s face.</li>
		<li>Perform an air leak test instructing the patient to cover the hole in the mask and breathe out. No sound should be heard.</li>
		<li>Connect the pink flow ends, one to the hole of the mask and the other to the wires of the EST equipment.</li>
		<li>Wait for automatic calibration of the EST equipment&#39;s gas analysis elements, ensuring the environmental CO2 does not exceed 1,200 ppm.</li>
		<li>Instruct the patient to uncover the chest area and clean the skin with 70% isopropyl alcohol before placing the electrodes. Shave the area if necessary.</li>
		<li>Connect the 12-lead electrocardiographic electrodes on the patient&#180;s chest according to the modified Mason-Likar22 standardization method and AHA scientific statement: exercise standards for testing and training20,21 as described below.
		<ol>
			<li>Place four electrodes on the arms: one on the right arm (RA) over the acromion bone, one on the left arm (LA) over the acromion bone, one on the right costal margin (RCM), and one on the left costal margin (LCM).</li>
			<li>Then, place six electrodes on the chest: V1 on the second intercostal space and over the right border of the sternum, V2 on the second intercostal space and the left border of the sternum, V3 between V2 and V4, V4 on the fourth intercostal space crossing with the left midclavicular line, V5 on the fifth intercostal space at the level of the left anterior axillary line and V6 on the sixth intercostal space at the level of the left middle axillary line.</li>
		</ol>
		</li>
		<li>Perform a resting spirometry instructing the patient to inhale deeply as much as possible, then indicate to exhale as fast and forcefully as possible, trying to maintain at least 6 s in the breath-out effort.</li>
		<li>Evaluate the reproducibility and quality criteria of the resting spirometry by repeating the breath-out effort 3x.</li>
		<li>Evaluate the forced expiratory volume in 1 s (VEF1) and the forced vital capacity (FVC) parameters provided in the EST system.</li>
		<li>Choose the best parameters the patient achieves according to VEF1/FVC to monitor it during the test.</li>
	</ol>
	</li>
</ol>
5. Performing the EST
<ol>
	<li>Evaluate the cardiac conditions (baseline electrocardiogram [EKG], heart rate, and blood pressure) to ensure the patient does not present limiting factors before starting the EST.</li>
	<li>Explain to the patient that the perceived physical effort during the EST is measured using the Borg scale from 0 to 2020.</li>
	<li>Monitor and evaluate the EST with attention to blood pressure, heart rate, and electrocardiographic trace changes every 3 min. Continue monitoring the perception of any symptoms (chest pain, shortness of breath, dizziness, or extreme fatigue) and the perceived physical effort by the Borg scale. Perform these evaluations as follows.
	<ol>
		<li>Blood pressure: Measure systolic and diastolic blood pressure every 3 min with a pneumatic device to evaluate a rise in systolic blood pressure proportional to the exercise load.</li>
		<li>Heart rate: Record beat by beat, in real-time, using 12-lead telemetry (stress electrocardiogram) to expect a linear increase in this variable with increasing load. Also, analyze the heart rhythm to differentiate it from non-sinus rhythms and detect arrhythmias by telemetry.</li>
		<li>Symptoms and signs: During the procedure, ask the patient if there is any discomfort, such as pain in the chest or extremities, difficulty breathing, altered alertness, decreased visual acuity, dizziness, or gait instability, and evaluate if exists the presence of low heart rate, oxygen saturation, or blood pressure.</li>
		<li>Perception of effort: As the procedure progresses, ask the patient about the degree of effort according to the Borg scale from 0 to 20. The lower numbers indicate light efforts, while the higher ones are heavy.</li>
		<li>Stop the EST if the patient achieves &#62; 85% of their heart rate (calculated according to age) or if the patient experiences any discomfort during the effort or shows significant electrocardiographic disturbances (ischemia or complex arrhythmias).</li>
	</ol>
	</li>
	<li>After EST is finished, monitor closely the patient&#180;s blood pressure, heart rate, and EKG during the next 1 min, 3 min, 5 min, and 8 min (recovery period), and ensure these parameters return to baseline values.</li>
	<li>Extract and register cardiopulmonary data from the EST software: METS, VO2, and HR/O2.</li>
</ol>

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The authors have nothing to disclose.

Although BIA is considered a safe, practical, and noninvasive method, which overcomes the limitations of other methods to measure body composition and body water19,23, it is relevant to consider the potential bias occurring regarding the type of bioelectrical impedance (the method described here is specific for a single-frequency bioelectrical impedance device), or the variation in the steps and technique verification methods.
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Ischemic heart disease (IHD) represents a group of clinical syndromes characterized by myocardial ischemia, a mismatch in the myocardial blood supply and demand. The underlying pathophysiological defect includes inadequate perfusion, mainly due to atherosclerotic disease of epicardial coronary arteries1,2,3. In general, the presence of cardiovascular disease (CVD) is common, showing poor survival worldwide4. Particularly in 2015, IHD contributed to approximately 9 million deaths and more than 160 million disability-adjusted life years, and nowadays, IHD remains one of the main causes of mortality, and it favors the heart disease burden around the world5.
To evaluate both the presence and prognosis of IHD, some non-invasive procedures like the exercise stress test (EST) are routinely used. EST provides an assessment of the overall performance of cardiovascular, muscular, pulmonary, hematopoietic, neurosensory, and skeletal systems when the maximum tolerable stress appears under the EST6.
Under normal conditions, physiological adaptations would be expected while exercising. During exercise, several changes occur, like a dynamic change of fluid in blood within the vascular compartment, the reduction of plasma and blood volume, and the increase in hematocrit and plasma metabolite concentrations. Reduced plasma volume normalizes approximately 1 h after exercise, which may also vary depending on individual training level and water replenishment7.
However, IHD may lead to an acute impaired response to exercise, affecting EST performance in some variables comprising aerobic capacity and exercise tolerance, such as oxygen uptake (VO2) and heart rate/oxygen pulse (HR/O2)8. Recently, hydration status (HS), a measure of the water contained in the body1, has been proposed as a factor linked to plasma volume, able to modify blood flow and viscosity. HS has also been related to systolic volume, heart rate, and arteriovenous oxygen difference, determinants of VO2. Furthermore, some studies describe the relation of HS with a lower cardiopulmonary response (cardiac chronotropic and inotropic, VO2 and HR/O2)9.
In addition, several factors like age, environmental conditions, the level of physical activity/exercise, and dietary factors like fluid intake have been described to participate in HS balance10. Likewise, pathophysiological conditions such as IHD and its progression may influence HS11.
Although HS closely relates to cardiopulmonary, biological-environmental responses or lifestyle factors, the particular association of IHD in population with previous conditions has been scantily addressed; and it represents a significant challenge for clinical research, specifically due to the assessment of early stages, as well as the requirement for reliable and standardized methods to evaluate the HS.
To address this, bioelectrical impedance analysis (BIA), a practical, non-invasive, and cost-effective method, can be used to estimate body composition within a clinical setting but also has been proposed as an alternative method to evaluate HS showing advantages over other methods like biomarkers tests (urinary or plasma osmolality) due to the presence of high variability in the results and even over the gold standard method (isotope dilution) due to the complexity of the technique that requires specific training and highly cost equipment, becoming clinically impractical12,13,14,15.
The conventional BIA method applies an alternating, low electric current intensity (below the perceptual thresholds), entering the human body and crossing internal tissues. Then, based on the principle that body organs may act as electric conductors or dielectrics, we may obtain a register of electric impedance (or bioelectrical impedance [Z]) that reflects the opposition of the organs to the free applied electric flow (EF), depending on their composition (fat or muscle mass, bone, water, etc.)12. Here, Z sources are resistance (R) and reactance (Xc). The former is related to the opposition of the EF throughout cellular ionic solutions (intracellular and extracellular), while the latter is a capacitive component of tissue interfaces, cell membranes, and organelles12.
In addition, bioelectrical impedance vector analysis (BIVA) is an alternative BIA method approach that uses spatial relationships between R and Xc (both adjusted by height) to assess soft tissue hydration. The R and Xc data are plotted on a bivariate resistance-reactance graph, which allows visualizing body composition and HS12,16.
Considering the less explored field of HS balance associated with cardiopulmonary, as well as the growing interest to characterize new applications of methods like BIVA in the evaluation of HS, this study aims to determine HS by BIVA method and to analyze HS relation with VO2 and HR/O2 in ambulatory patients with IHD.

<table><tbody><tr><td>BIVA Tolerance</td><td>BIVA SOFTWARE 2002</td><td></td><td>Piccoli A, Pastori G: BIVA software. Department of Medical and Surgical Sciences, University of Padova, Padova, Italy, 2002 (available at E-mail:apiccoli@unipd.it).</td></tr><tr><td>Cardiopoint ECG C600</td><td>BTL</td><td>407-80MANEN03100</td><td>ELECTROCARDIOGRAPH</td></tr><tr><td>Cardiopoint Trolley</td><td>BTL</td><td>40700B000240</td><td>TROLLEY</td></tr><tr><td>Portable Digital Flat Scale</td><td>SECA</td><td>813</td><td>DIGITAL FLAT SCALE</td></tr><tr><td>Portable Stadiometer</td><td>SECA</td><td>213</td><td>STADIOMETER</td></tr><tr><td>Quantum IV</td><td>RJL SYSTEMS</td><td>Q4B-2405</td><td>BIOELECTRIC IMPEDANCE ANALYZER</td></tr><tr><td>Treadmill Clinical</td><td>BTL</td><td>216A18</td><td>TREADMILL</td></tr></tbody></table>

evaluation of hydration status by bioelectrical impedance vector analysis in patients with ischemic heart disease undergoing exercise stress test

Ischemic heart disease (IHD) represents a group of clinical syndromes characterized by myocardial ischemia, leading to an impairment in the myocardial blood supply and compromised perfusion. Several clinical variables assessed through a stress test, such as oxygen uptake (VO2) and heart rate oxygen pulse (HR/O2), have been attributed as cardiopulmonary prognostic factors in patients with IHD. However, other factors like hydration status (HS), potentially affecting the cardiopulmonary response, have been barely addressed. Unbalanced HS has a short-term effect on plasma volume and the sympathetic nervous system, which impacts blood volume, and lowers VO2 and HR/O2. Recently, bioelectrical impedance analysis (BIA), a method based on the opposition of body tissues (including fluid volume) to a low electrical current, has been widely used to assess HS by obtaining two components: resistance (R) and reactance (Xc) and using prediction formulas. However, several limitations as chronic illness or abnormal fluid status, may affect the results. In this sense, alternative BIA methods, such as bioelectrical impedance vector analysis (BIVA), have become relevant. R and Xc (adjusted by height) result in a vector plotted on the R/Xc graph, which allows interpreting the HS as normal or abnormal according to the distance of the mean vector. This study aims to describe how to determine HS by BIVA using a single-frequency device and compare the results with the cardiopulmonary response in patients with IHD.

First, R and Xc (both adjusted by patient&#180;s height) data registered from the single frequency (SF-BIA) device was used to obtain the BIVA R/Xc graph. Second, we classified hydration status as euhydration, hyperhydration, and hypohydration. Representative hydration data from male patients plotted with circle and triangle, aged 66 years and 67 years, weighing 72.2 kg and 72.3 kg, height 169 cm and 163 cm, are shown (Figure 2). In addition, impedance data are shown R/H= 280.7, Xc/H= 23.6 &...

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Evaluation of Hydration Status by Bioelectrical Impedance Vector Analysis in Patients with Ischemic Heart Disease Undergoing Exercise Stress Test

Hydration status imbalances can have a short-term effect on direct and indirect determinants of oxygen uptake and pulse, and morbidity and mortality prognostic factors in ischemic heart disease. This protocol describes the technique for assessment of hydration status through bioelectrical impedance vector analysis and cardiopulmonary response during exercise stress test.

Ischemic heart disease (IHD) represents a group of clinical syndromes characterized by myocardial ischemia, leading to an impairment in the myocardial ...

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545 Views.  Centro Médico Nacional “20 de Noviembre”, ISSSTE. Ons protocol heeft tot doel klinisch het nut aan te tonen van het evalueren van de hydratatiestatus met behulp van biologische impedantieanalyse bij patiënten met ischemische hartziekte, en hoe de hydratatiestatus kan worden vergeleken met cardiopulmonale respons, geëvalueerd door inspanningsstresstest. Onlangs is de hydratatiestatus voorgesteld als een factor die verband houdt met het plasmavolume, in staat om de bloedstroom en viscositeit te wijzigen, wat van invloed is op het systolische...

Video: Evaluation of Hydration Status by Bioelectrical Impedance Vector Analysis in Patients with Ischemic Heart Disease Undergoing Exercise Stress Test

Examining the Characteristics of Episodic Memory using Event-related Potentials in Patients with Alzheimer's Disease

Our laboratory uses event-related EEG potentials (ERPs) to understand and support behavioral investigations of episodic memory in patients with amnestic mild cognitive impairment (aMCI) and Alzheimer's disease (AD). Whereas behavioral data inform us about the patients' performance, ERPs allow us to record discrete changes in brain activity. Further, ERPs can give us insight into the onset, duration, and interaction of independent cognitive processes associated with memory retrieval. In patient populations, these types of studies are used to examine which aspects of memory are impaired and which remain relatively intact compared to a control population. The methodology for collecting ERP data from a vulnerable patient population while these participants perform a recognition memory task is reviewed. This protocol includes participant preparation, quality assurance, data acquisition, and data analysis. In addition to basic setup and acquisition, we will also demonstrate localization techniques to obtain greater spatial resolution and source localization using high-density (128 channel) electrode arrays.

The methodology for collecting high-density event-related potential data while patients with Alzheimer's disease perform a recognition memory task is reviewed. This protocol will include subject preparation, quality assurance, data acquisition, and data analysis.

Our laboratory uses event-related EEG potentials (ERPs) to understand and support behavioral investigations of episodic memory in patients with amnestic ...

Gene Transfer for Ischemic Heart Failure in a Preclinical Model

Various emerging technologies are being developed for patients with heart failure. Well-established preclinical evaluations are necessary to determine their efficacy and safety.
Gene therapy using viral vectors is one of the most promising approaches for treating cardiac diseases. Viral delivery of various different genes by changing the carrier gene has immeasurable therapeutic potential.
In this video, the full process of an animal model of heart failure creation followed by gene transfer is presented using a swine model. First, myocardial infarction is created by occluding the proximal left anterior descending coronary artery. Heart remodeling results in chronic heart failure. Unique to our model is a fairly large scar which truly reflects patients with severe heart failure who require aggressive therapy for positive outcomes. After myocardial infarct creation and development of scar tissue, an intracoronary injection of virus is demonstrated with simultaneous nitroglycerine infusion. Our injection method provides simple and efficient gene transfer with enhanced gene expression. This combination of a myocardial infarct swine model with intracoronary virus delivery has proven to be a consistent and reproducible methodology, which helps not only to test the effect of individual gene, but also compare the efficacy of many genes as therapeutic candidates.

A method of gene transfer for the treatment of ischemic heart failure is described using a swine model of myocardial infarction. Our simple and reproducible method enables us to readily evaluate the efficacy of various gene transfers with a very simple and reproducible way.

Various emerging technologies are being developed for patients with heart failure. Well-established preclinical evaluations are necessary to determine ...

Cardiac Stress Test Induced by Dobutamine and Monitored by Cardiac Catheterization in Mice

Dobutamine is a &beta;-adrenergic agonist with an affinity higher for receptor expressed in the heart (&beta;1) than for receptors expressed in the arteries (&beta;2). When systemically administered, it increases cardiac demand. Thus, dobutamine unmasks abnormal rhythm or ischemic areas potentially at risk of infarction. 
Monitoring of heart function during a cardiac stress test can be performed by either ecocardiography or cardiac catheterization. The latter is an invasive but more accurate and informative technique that the former.
Cardiac stress test induced by dobutamine and monitored by cardiac catheterization accomplished as described here allows, in a single experiment, the measurement of the following hemodynamic parameters: heart rate (HR), systolic pressure, diastolic pressure, end-diastolic pressure, maximal positive pressure development (dP/dtmax) and maximal negative pressure development (dP/dtmin), at baseline conditions and under increasing doses of dobutamine.
As expected, in normal mice we observed a dobutamine dose-related increase in HR, dP/dtmax and dP/dtmin. Moreover, at the highest dose tested (12 ng/g/min) the cardiac decompensation of high fat diet-induced obese mice was unmasked.

We describe the protocol to perform a cardiac stress test induced by dobutamine and monitored by cardiac catheterization in normal mice. Also we show its application to unmask subclinical cardiac disease in high fat diet-induced obese mice.

Dobutamine is a &beta;-adrenergic agonist with an affinity higher for receptor expressed in the heart (&beta;1) than for receptors expressed in the ...

Computerized Dynamic Posturography for Postural Control Assessment in Patients with Intermittent Claudication

Computerized dynamic posturography with the EquiTest is an objective technique for measuring postural strategies under challenging static and dynamic conditions. As part of a diagnostic assessment, the early detection of postural deficits is important so that appropriate and targeted interventions can be prescribed. The Sensory Organization Test (SOT) on the EquiTest determines an individual&#39;s use of the sensory systems (somatosensory, visual, and vestibular) that are responsible for postural control. Somatosensory and visual input are altered by the calibrated sway-referenced support surface and visual surround, which move in the anterior-posterior direction in response to the individual&#39;s postural sway. This creates a conflicting sensory experience. The Motor Control Test (MCT) challenges postural control by creating unexpected postural disturbances in the form of backwards and forwards translations. The translations are graded in magnitude and the time to recover from the perturbation is computed.
Intermittent claudication, the most common symptom of peripheral arterial disease, is characterized by a cramping pain in the lower limbs and caused by muscle ischemia secondary to reduced blood flow to working muscles during physical exertion. Claudicants often display poor balance, making them susceptible to falls and activity avoidance. The Ankle Brachial Pressure Index (ABPI) is a noninvasive method for indicating the presence of peripheral arterial disease and intermittent claudication, a common symptom in the lower extremities. ABPI is measured as the highest systolic pressure from either the dorsalis pedis or posterior tibial artery divided by the highest brachial artery systolic pressure from either arm. This paper will focus on the use of computerized dynamic posturography in the assessment of balance in claudicants.

Individuals with intermittent claudication exhibit poor balance compared to healthy controls. Computerized dynamic posturography is an objective method for measuring an individual's postural responses to balance disturbances. This provides an objective reflection of the person&#x2019;s ability to respond to situations under which sensory stimuli are altered and unexpected perturbations occur.

Computerized dynamic posturography with the EquiTest is an objective technique for measuring postural strategies under challenging static and dynamic ...

Assessment of Vascular Function in Patients With Chronic Kidney Disease

Patients with chronic kidney disease (CKD) have significantly increased risk of cardiovascular disease (CVD) compared to the general population, and this is only partially explained by traditional CVD risk factors. Vascular dysfunction is an important non-traditional risk factor, characterized by vascular endothelial dysfunction (most commonly assessed as impaired endothelium-dependent dilation [EDD]) and stiffening of the large elastic arteries. While various techniques exist to assess EDD and large elastic artery stiffness, the most commonly used are brachial artery flow-mediated dilation (FMDBA) and aortic pulse-wave velocity (aPWV), respectively. Both of these noninvasive measures of vascular dysfunction are independent predictors of future cardiovascular events in patients with and without kidney disease. Patients with CKD demonstrate both impaired FMDBA, and increased aPWV. While the exact mechanisms by which vascular dysfunction develops in CKD are incompletely understood, increased oxidative stress and a subsequent reduction in nitric oxide (NO) bioavailability are important contributors. Cellular changes in oxidative stress can be assessed by collecting vascular endothelial cells from the antecubital vein and measuring protein expression of markers of oxidative stress using immunofluorescence. We provide here a discussion of these methods to measure FMDBA, aPWV, and vascular endothelial cell protein expression.

The degree of vascular dysfunction and contributing physiological mechanisms can be assessed in patients with chronic kidney disease by measuring brachial artery flow-mediated dilation, aortic pulse-wave velocity, and vascular endothelial cell protein expression.

Patients with chronic kidney disease (CKD) have significantly increased risk of cardiovascular disease (CVD) compared to the general population, and this ...

Implantation of Total Artificial Heart in Congenital Heart Disease

In patients with end-stage heart failure (HF), a total artificial heart (TAH) may be implanted as a bridge to cardiac transplant. However, in congenital heart disease (CHD), the malformed heart presents a challenge to TAH implantation. 
In the case presented here, a 17 year-old patient with congenital transposition of the great arteries (CCTGA) experienced progressively worsening HF due to his congenital condition. He was hospitalized multiple times and received an implantable cardioverter defibrillator (ICD). However, his condition soon deteriorated to end-stage HF with multisystem organ failure. 
Due to the patient's grave clinical condition and the presence of complex cardiac lesions, the decision was made to proceed with a TAH. The abnormal arrangement of the patient's ventricles and great arteries required modifications to the TAH during implantation.
With the TAH in place, the patient was able to return home and regain strength and physical well-being while awaiting a donor heart. He was successfully bridged to heart transplantation 5 months after receiving the device. This report highlights the TAH is feasible even in patients with structurally abnormal hearts, with technical modification.

This is a case report of a patient with congenitally corrected transposition of the great arteries (CCTGA) who received a total artificial heart (TAH) as a bridge to heart transplant. The TAH was successfully implanted with modifications to accommodate the patient's congenitally malformed heart.

In patients with end-stage heart failure (HF), a total artificial heart (TAH) may be implanted as a bridge to cardiac transplant. However, in congenital ...

Characterization of Metabolic Status in Nonhuman Primates with the Intravenous Glucose Tolerance Test

The intravenous glucose tolerance test (IVGTT) plays a key role in the characterization of glucose homeostasis. When taken together with serum biochemical profiles, inclusive of blood glucose levels in both the fed and fasted state, HbA1c, insulin levels, clinical history of diet, body composition, and body weight status, an assessment of normal and abnormal glycemic control can be made. Interpretation of an IVGTT is done through measurement of changes in glucose and insulin levels over time in relation to the dextrose challenge. Critical components to be considered are: peak glucose and insulin levels reached in relation to T0 (end of glucose infusion), the glucose clearance rate K derived from the slope of rapid glucose clearance in the first 20 min (T1 to T20), the time to return to glucose baseline, and the area under the curve (AUC). These IVGTT measures will show characteristic changes as glucose homeostasis moves from a healthy to a diseased metabolic state5. Herein we will describe the characterization of nonhuman primates (Rhesus and Cynomolgus macaques), which are the most relevant animal model of Type II diabetes (T2D) in humans and the IVGTT and clinical profiles of these animals from a lean healthy, to obese dysmetabolic, and T2D state 8, 10, 11.

The goal of this protocol is to present a standard method to perform intravenous glucose tolerance tests (IVGTTs) to assess glycemic control in nonhuman primates and assess their metabolic status from healthy to dysmetabolic.

The intravenous glucose tolerance test (IVGTT) plays a key role in the characterization of glucose homeostasis. When taken together with serum biochemical ...

Evaluation of Fluid Overload by Bioelectrical Impedance Vectorial Analysis

Early detection and management of fluid overload are critically important in acute illness, as the impact of therapeutic intervention can result in decreased or increased mortality rates. Accurate fluid status assessment entails appropriate therapy. Unfortunately, as the gold standard method of radioisotopic fluid measurement is costly, time-consuming, and lacks sensitivity in the acute care clinical setting, other less-accurate methods are typically used, such as clinical examination or 24 h output. Bioelectrical impedance vectorial analysis (BIVA) is an alternative impedance-based approach, where the raw parameter resistance and reactance of a subject are plotted to produce a vector, the position of which can be evaluated relative to tolerance intervals in an R-Xc graph. The fluid status is then interpreted as normal or abnormal, based on the distance from the mean vector derived from a healthy reference population. The objective of the present study is to demonstrate how to evaluate the presence of fluid overload through bioelectrical impedance vectorial analysis and the impedance ratio measured with tetrapolar multi-frequency equipment in patients admitted to the emergency department.

In this study, we demonstrate how to evaluate the presence of fluid overload through bioelectrical impedance vectorial analysis (BIVA) and the impedance ratio measured using tetrapolar multi-frequency equipment in patients admitted to the emergency department. BIVA and impedance ratio are reliable and useful tools to predict poor outcomes.

Early detection and management of fluid overload are critically important in acute illness, as the impact of therapeutic intervention can result in ...

Predicting Prognosis in Acute Heart Failure Using Phase Angle & BIVA Z-Scores

Clinical Application of Phase Angle and BIVA Z-Score Analyses in Patients Admitted to an Emergency Department with Acute Heart Failure

Acute heart failure is characterized by neurohormonal activation, which leads to sodium and water retention and causes alterations in body composition, such as increased body fluid congestion or systemic congestion. This condition is one of the most common reasons for hospital admission and has been associated with poor outcomes. The phase angle indirectly measures intracellular status, cellular integrity, vitality, and the distribution of spaces between intracellular and extracellular body water. This parameter has been found to be a predictor of health status and an indicator of survival and other clinical outcomes. In addition, phase angle values of &lt;4.8&#176; upon admission were associated with higher mortality in patients with acute heart failure. However, low phase angle values may be due to alterations-such as the shifting of fluids from an intracellular body water (ICW) compartment to an ECW (extracellular body water) compartment and a concurrent decrease in body-cell mass (which can reflect malnutrition)-that are present in heart failure. Thus, a low phase angle may be due to overhydration and/or malnutrition. BIVA provides additional information about the body-cell mass and congestion status with a graphical vector (R-Xc graph). In addition, a BIVA Z-score analysis (the number of standard deviations from the mean value of the reference group) that has the same pattern as that of the ellipses for the percentiles on the original R-Xc graph can be used to detect changes in soft-tissue mass or tissue hydration and can help researchers compare changes in different study populations. This protocol explains how to obtain and interpret phase angle values and BIVA Z-score analyses, their clinical applicability, and their usefulness as a predictive marker for the prognosis of a 90-day event in patients admitted to an emergency department with acute heart failure.

Author Spotlight: Unveiling Prognostic Indicators in Heart Failure - The Role of Phase Angle and Bioelectrical Impedance Analysis 

In this protocol, we explain how to obtain and interpret phase angle values and bioelectrical impedance vectorial analysis (BIVA) Z-score obtained by bioelectrical impedance in patients with acute heart failure admitted to the Emergency Department and their clinical applicability as a predictive marker for the prognosis of a 90-day event.

Acute heart failure is characterized by neurohormonal activation, which leads to sodium and water retention and causes alterations in body composition, ...

Developing an Exercise Program for Rheumatoid Arthritis Patients

Evaluation of Changes in Hydration and Body Cell Mass with Bioelectrical Impedance Analysis after Exercise Program for Rheumatoid Arthritis Patients

Rheumatoid arthritis (RA) is a debilitating disease that can result in complications such as rheumatoid cachexia. While physical exercise has shown benefits for RA patients, its impact on hydration and body cell mass remains uncertain. The presence of pain, inflammation, and joint changes often restrict activity and make traditional body composition assessments unreliable due to altered hydration levels. Bioelectrical impedance is a commonly used method for estimating body composition, but it has limitations since it was primarily developed for the general population and does not consider changes in body composition. On the other hand, bioelectrical impedance vectorial analysis (BIVA) offers a more comprehensive approach. BIVA involves graphically interpreting resistance (R) and reactance (Xc), adjusted for height, to provide valuable information about hydration status and the integrity of the cell mass.
Twelve women with RA were included in this study. At the beginning of the study, hydration and body cell mass measurements were obtained using the BIVA method. Subsequently, the patients participated in a six-month dynamic exercise program encompassing cardiovascular capacity, strength, and coordination training. To evaluate changes in hydration and body cell mass, the differences in the R and Xc parameters, adjusted for height, were compared using BIVA confidence software. The results showed notable changes: resistance decreased after the exercise program, while reactance increased. BIVA, as a classification method, can effectively categorize patients into dehydration, overhydration, normal, athlete, thin, cachectic, and obese categories. This makes it a valuable tool for assessing RA patients, as it provides information independent of body weight or prediction equations. Overall, the implementation of BIVA in this study shed light on the effects of the exercise program on hydration and body cell mass in RA patients. Its advantages lie in its ability to provide comprehensive information and overcome the limitations of traditional body composition assessment methods.

Author Spotlight: Implementation of BIVA for Analyzing Disease Risk Factors in Patients with Low Body Cell Mass 

This protocol assesses alterations in hydration and body cell mass status using bioelectrical impedance vectorial analysis following a dynamic exercise program designed for patients with rheumatoid arthritis. The dynamic exercise program itself is detailed, highlighting its components focused on cardiovascular capacity, strength, and coordination. The protocol details steps, instruments, and limitations.

Rheumatoid arthritis (RA) is a debilitating disease that can result in complications such as rheumatoid cachexia. While physical exercise has shown ...

Evaluation of Hydration Status by Bioelectrical Impedance Vector Analysis in Patients with Ischemic Heart Disease Undergoing Exercise Stress Test

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