The authors would like to thank Prof(s). Piccoli and Pastori of the Department of Medical and Surgical Sciences, University of Padova, Italy, for providing the BIVA software. This research did not receive any specific grant from funding, agencies in the public, commercial, or not-for-profit sectors. This protocol/research is part of the Ph.D. dissertation of Mar&#237;a Fernanda Bernal-Ceballos supported by the National Council of Science and Technology (CONACYT) scholarship (CVU 856465).

The protocol was approved by the Research Ethics Committee of the National Institute of Medical Sciences and Nutrition Salvador Zubir&#225;n (REF. 3057). To conduct BIA measurements, tetrapolar multiple-frequency equipment was used (see Table of Materials). This equipment provided accurate raw values for the resistance (R), reactance (Xc), and phase angle (PhA) at a frequency of 50 kHz, which allowed the impedance to be measured with the best signal-to-noise ratio. The adhesive electrodes used needed to correspond to the manufacturer&#39;s recommendations. Informed written consent was obtained from the patients involved in the study.
1. Experimental and patient preparation
NOTE: These steps were performed before performing a BIA measurement.
<ol>
	<li>Periodically test the equipment to check the accuracy of impedance measurements by using a test resistor with a known value of 500 &#937; (range: 496-503 &#937;).</li>
	<li>Educate the personnel performing the BIA measurements according to the manufacturer&#39;s instructions and the tetrapolar method described in the literature36. 
	NOTE: The patient must fast for at least 4-5 h. If the patient is lucid and conscious, explain the procedure that will be conducted.</li>
	<li>Remove the shoe and sock from the right foot and any metal objects that have contacts with the patient&#39;s skin, such as bracelets, watches, rings, and chains. 
	NOTE: If the right foot has an injury, bandage it, and switch to the left side (if neither foot is available to be uncovered and for the placement of electrodes, BIA measurements cannot be performed).</li>
	<li>Place the patient in a supine or semi-fowler position according to the patient&#39;s tolerance, with their legs and arms spread at an angle of about 45&#176;. In patients with obesity, place a sheet between their thighs to avoid contact between them.</li>
	<li>Connect the lead wires to the equipment; there are indications showing the correct way to connect them.</li>
</ol>
2. BIA measurement
<ol>
	<li>Identify the area in which the electrodes will be placed. With a 70% alcohol pad, clean these surfaces and wait until the alcohol dries to place the electrodes (the location of the electrodes was previously described)37. 
	&#8203;NOTE: For details on BIA measurement, refer to the protocol previously described37.</li>
</ol>
3. Analysis of BIA raw parameters on the R-Xc Z-score graph
<ol>
	<li>Download the BIVA tolerance software by Piccolli38 (see Table of Materials). 
	NOTE: The software includes seven workbook sheets (Guide/Reference population/Point graph/Path/Subjects/Z-scores/Z-graph).</li>
	<li>Click on the Reference population sheet, choose the reference population according to the patient&#39;s characteristics, and copy and paste it into the first yellow row. 
	NOTE: The software only reads the first yellow row, which is where the reference population is placed. The reference populations go from 1 to 10 (Popul code column), and they are shown in the rows below the yellow one.</li>
	<li>Click on the Z-score sheet, insert the reference population, and enter the patient&#39;s data into the second row. 
	NOTE: The reference population data include the population code (Popul Code), the number of patients included in the reference population (Popul Size, N), the mean resistance in ohms by height in m2 (R/H Mean), the standard deviation of the resistance in ohms by height in m2 (R/H SD), the mean reactance in ohms by height in m2 (Xc/H Mean), and the standard deviation of reactance in ohms by height in m2 (Xc/H SD). These data are shown in the reference population sheet (columns A to F).
	<ol>
		<li>Insert the medical record number of each patient into the Subject ID field (column G).</li>
		<li>Insert a number between 1 and 10 into the Group Code field (column H).</li>
		<li>Insert the resistance value obtained with BIA and adjusted by height in meters into the R/H subject field (column I).</li>
		<li>Insert the reactance value obtained with BIA and adjusted by height in meters into the Xc/H subject field (column J).</li>
		<li>Insert a value of 1 into the Drawing option field (column K) to create a plot; to skip rows, leave the cell blank.</li>
	</ol>
	</li>
	<li>Click on the spreadsheet program menu, click on the Complements tab, and click the CALCULATE button. 
	&#8203;NOTE: The Z(R) score (column L) Z(Xc) score (column M) will be automatically calculated.</li>
	<li>Click on the Z-graph sheet; then, in the spreadsheet program menu, click the Add-ins tab and the New graph button.</li>
	<li>Perform BIVA Z-score and phase angle analyses following step 4 and step 5.</li>
</ol>
4. Interpretation and analysis of the BIVA Z-score
NOTE: Identify the four patterns in the R-Xc Z-score graph. In the extremes along the major axis, the lower pattern is associated with congestion, whereas the upper pattern is associated with dehydration status. In the extremes along the minor axis, the left pattern is associated with more cell mass in soft tissues, whereas the right pattern is associated with less cell mass in soft tissues. To calculate the bivariate Z-score from the mean age of the group, the following formula is used: Z(R) = (R/H mean age group - R/H mean value in the reference population) / standard deviation of the reference population and Z(Xc) = (Xc/H mean age of the group - Xc/H mean value in the reference population) / standard deviation of the reference population.
<ol>
	<li>Visualize and identify the 50%, 75%, and 95% ellipses. The x (reactance) and y (resistance) axes show the standard deviations. 
	NOTE: The sex-specific R-Xc Z-score graph is classified according to the hydration status and BCM, and all vectors within the 75% tolerance ellipse are considered to indicate tissue with normal impedance.</li>
	<li>Identify the axis of the hydration status and classify the vector. 
	NOTE: Vectors that fall below the 75% tolerance ellipse in the lower pole indicate congestion, whereas all vectors that fall within the 75% tolerance ellipse indicate no congestion. Vectors falling outside the 75% tolerance ellipse of the upper pole are considered to indicate dehydration status.</li>
	<li>Identify the BCM axis on the graph and classify the vector. 
	NOTE: Vectors with displacement to the left side are considered to indicate greater BCM. Contrarily, vectors on the right side of the graph are classified as indicating lower BCM.</li>
	<li>Identify the number of standard deviations between the plotted and the mean value of the reference group. 
	NOTE: Vectors that fall below the 75% tolerance ellipses of the lower pole (major axis) and outside the 75% ellipses on the left side (minor axis) are interpreted as indicating congestion status with a decrease in BCM (less soft tissue), while vectors that fall on the right side (minor axis) are interpreted as indicating congestion status with an increase in BCM (more soft tissue).</li>
	<li>On the other hand, vectors that fall over the 75% tolerance ellipses of the lower pole (major axis) and outside the 75% ellipses on the left side (minor axis) are interpreted as indicating non-congestion status with a decrease in BCM (less soft tissue), while vectors that fall on the right side (minor axis) are interpreted as indicating non-congestion status with an increase in BCM (more soft tissue).</li>
</ol>
5. Directly calculating and interpreting PhA
NOTE: Raw R50 and Xc50 values are needed to calculate PhA.
<ol>
	<li>Substitute the raw R50 and Xc50 values into the formula. 
	NOTE: Formula in RStudio: atan(Xc50/R50)*(180&#176;/&#960;); formula in Microsoft Excel: =ATAN(Xc50/R50)*(180&#176;/PI). The results are expressed in degrees. 
	The PhA usually ranges between 5&#176; and 7&#176;; however, values above 9.5&#176; can be reached in healthy athletes. If the PhA values are lower than 4.8&#176; at admission, the subject has an HR of 2.7 (95%CI 1.08-7.1, p = 0.03)39 for presenting a 90-day event (mortality or re-hospitalization) and an HR of 2.67 for mortality in the next 24 months (95%CI 1.21-5.89, p = 0.01)20.</li>
</ol>

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

The authors declare no competing interests.

This protocol describes the utility of using R-Xc Z-score analysis in clinical practice for patients admitted to an emergency department with AHF. Considering that in patients with AHF, the main reason for hospital admission is congestion, its quick and accurate detection, and evaluation are crucial for patients&#39; outcomes6.
This article illustrates the variety of clinical manifestations of AHF and how BIVA Z-score analysis (congestion status and BCM) can be used to ...

Acute heart failure (AHF) results from the rapid onset of signs, symptoms, and exacerbation of derivates of HF and a combination of clinical, hemodynamic, and neurohormonal abnormalities, including systemic inflammatory activation, which leads to sodium and water retention1. This long-term accumulation causes the interstitial glycosaminoglycan (GAG) networks to become dysfunctional, resulting in reduced buffering capacity and changing the form and function of the GAG networks1,2.&#160;This contributes to alterations in body composition due to the shifting of fluids from intracellular to extracellular space3, thus inducing an increase in body fluids and leading to congestion, which is the most common cause of hospitalization with HF. It is principally fluid overload, compartmental fluid redistribution, or a combination of both mechanisms that require immediate medical attention4,5. This condition is one of the main predictors of a poor prognosis6,7.
Considering that AHF is the most common cause of hospital admissions in patients older than 65 years of age8, around 90% of those who are admitted to an emergency department present fluid overload6, and approximately 50% of these patients are discharged with persistent symptoms of dyspnea and fatigue, and/or minimal or no weight loss9. In-hospital mortality rates range from 4% to 8% after discharge; there is an increase from 8% to 15% at three months, and for re-hospitalization, the rates range from 30% to 38% at 3 months10. Therefore, the quick and accurate evaluation of congestion in real-time and acute settings, such as an emergency department, is crucial for therapeutic management11 and determining disease prognosis, morbidity, and mortality6.
Bioelectrical impedance analysis (BIA) has been suggested for estimating body composition for being safe, noninvasive and portable techinque12. To estimate a whole-body impedance, BIA uses a phase-sensitive impedance analyzer that introduces a constant alternating current through tetrapolar surface electrodes placed on the hands and feet12. This method combines the resistance (R), reactance (Xc), and phase angle (PhA)13, where R is the opposition to the flow of the alternating current through the intracellular and extracellular ionic solution. Xc is the delay in the conduction (dielectric components) or compliance of the tissue interfaces, cell membranes, and organelles with the passage of the administered current12. The PhA reflects the relationship between R and Xc. It is derived from the electrical properties of the tissue; it is expressed as the lag between the voltage and current at the cell membrane and tissue interfaces and is measured with phase-sensitive devices14,15,16,17.
The PhA is calculated from raw data&#160;on R and Xc (PA [degrees] = arctangent (Xc/R) x (180&#176;/&#960;)), and it is considered one of the indicators of cellular health and cell membrane structure18, as well as an indicator of the distribution of ICW and ECW spaces, i.e., altered redistributions of the compartments (specifically, changes from intracellular to extracellular water, which low phase angles can show)19. Thus, a low PhA value may be due to overhydration and/or malnutrition, and the Z-score could be used to differentiate if this low PhA is due to the loss of soft tissue mass, an increase in tissue hydration, or both. In addition, the transformation of the Z-score could help researchers compare changes in different study populations3,14.
In addition, PhA is considered a predictor of health status, an indicator of survival, and a prognostic marker for different clinical outcomes3,20, even under other clinical conditions20,21,22,23, where high PhA values indicate greater cell membrane integrity and vitality10,13and therefore greater functionality. This is in contrast to low PhA values, which reflect membrane integrity and permeability loss, leading to impaired cell function or even cell death14,22,24. In patients with chronic heart failure (CHF), smaller PhA values were associated with a worse functional class classification25. In addition, one of the advantages of PhA measurement is that it does not require recalled parameters, body weight, or biomarkers.
Several studies have recommended the use of raw BIA measurements in patients who had alterations in fluid shifts and fluid redistributions or non-constant hydration status, such as those in AHF26. This was because BIA is based on regression equations that estimate total body water (TBW), extracellular body water (ECW), and intracellular body water (ICW). Therefore, the lean and fat mass estimations in such patients are biased because of the physiological relationship with soft tissue hydration27.
The bioelectrical impedance vectorial analysis (BIVA) method overcomes some limitations of the conventional BIA method28. It provides additional information through a semiquantitative evaluation of body composition in terms of body-cell mass (BCM), cell mass integrity, and hydration status29. Thus, it allows an estimation of the body fluid volume through vector distribution and distance patterns on an R-Xc graph28,30. BIVA is used to create a vector plot of impedance (Z) using the whole-body R and Xc values derived from BIA at a frequency of 50 kHz.
To adjust the raw values of R and Xc, the parameters R and Xc are standardized by height (H), expressed as R/H and Xc/H in Ohm/m, and plotted as a vector; this vector has a length (proportional to the TBW) and a direction on the R-Xc graph16,28.
A sex-specific R-Xc graph contains three ellipses, which correspond to the 50%, 75%, and 95% tolerance ellipses of a healthy reference population28,31,32; the ellipsoidal form of the ellipses is determined by the relationship between R/H and Xc/H. However, to evaluate the impedance parameters in a gender-specific reference health population, the original raw BIA parameters were transformed into bivariate Z-scores (in a BIVA Z-score analysis) and plotted on an R-Xc Z-score graph33,34. This graph, compared with an R-Xc graph, represented the standardized R/H and Xc/H as a bivariate Z-score, i.e., Z(R) and Z(Xc) showed the number of standard deviations away from the mean value of the reference group33. The tolerance ellipses of the Z-score conserved the same pattern as that of the ellipses for the percentiles on the original R-Xc graph31,33. The Z-score graphs for R-Xc and R-Xc showed changes in soft tissue mass and tissue hydration independent of regression equations or body weight.
Vector displacements along the major axis of the ellipses indicated changes in hydration status; a shortened vector that fell below the 75% pole of an ellipse indicated pitting edema (sensibility = 75% and specificity = 86%); however, the optimal threshold for the detection of pitting edema was different in AHF and CHF patients, where the lower pole of 75% corresponded to AHF patients, and 50% corresponded to CHF patients edema (sensibility = 85% and specificity = 87%)35. On the other hand, vector displacements along the minor axis corresponded to cell mass. The left side of the ellipses indicated a high cell mass (i.e., more soft tissue), where shorter vectors corresponded to obese individuals and were characterized by phases similar to those of athletic ones, who had longer vectors. On the contrary, the right side indicated less body cell mass21,34; according to Picolli et al.31,33, the scores of the vectors of the anorexia, HIV, and cancer groups were located on the right side of the minor axis, which corresponds to the category of cachexia.
This study aimed to explain how to obtain and interpret PhA values by using BIA in patients with AHF who were admitted to an emergency department and to show their clinical applicability/usefulness as a predictive marker for the prognosis of 90-day events.

<table><tbody><tr><td>Alcohol 70% swabs&amp;nbsp;</td><td>NA</td><td>NA</td><td>Any brand can be used</td></tr><tr><td>BIVA software 2002</td><td>NA</td><td>NA</td><td>Is a sofware created for academic use, can be download in http:// www.renalgate.it/formule_calcolatori/ bioimpedenza.htm in &quot;LE FORMULE DEL Prof. Piccoli&quot; section</td></tr><tr><td>Chlorhexidine Wipes</td><td>NA</td><td>NA</td><td>Any brand can be used</td></tr><tr><td>Examination table</td><td>NA</td><td>NA</td><td>Any brand can be used</td></tr><tr><td>Leadwires square socket</td><td>BodyStat</td><td>SQ-WIRES</td><td></td></tr><tr><td>Long Bodystat 0525 electrodes</td><td>BodyStat</td><td>BS-EL4000</td><td></td></tr><tr><td>Quadscan 4000 equipment</td><td>BodyStat</td><td>BS-4000</td><td>Impedance measuring range:&lt;br/&gt; 20 - 1300 &amp;Omega; ohms&lt;br/&gt; Test Current: 620 &amp;mu;A&lt;br/&gt; Frequency: 5, 50, 100, 200 kHz Accuracy: Impedance 5 kHz: +/- 2 &amp;Omega; Impedance 50 kHz: +/- 2 &amp;Omega; Impedance 100 kHz: +/- 3 &amp;Omega; Impedance 200 kHz: +/- 3 &amp;Omega;&lt;br/&gt; Resistance 50 kHz: +/- 2 &amp;Omega;&lt;br/&gt; Reactance 50 kHz: +/- 1 &amp;Omega;&lt;br/&gt; Phase Angle 50 kHz: +/- 0.2&amp;deg; Calibration: A resistor is supplied for independent verification from time to time.&lt;br/&gt; The impedance value should read between 496 and 503 &amp;Omega;.</td></tr></tbody></table>

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.

According to the protocol described above, we present data from four AHF patients (two females and two males) who were admitted to an emergency department as an example of the clinical applicability of phase angle values and BIVA Z-score analysis. BIA measurements were performed using phase-sensitive multiple-frequency equipment within 24 h of admission.
To calculate the bivariate Z-score from the mean of the age group, the following formula was used: Z(R) = (R/H mean value of the age group - ...

Watch this Scientific Journal Video about Unveiling Prognostic Indicators in Heart Failure - The Role of Phase Angle and Bioelectrical Impedance Analysis at JoVE.com

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.

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, ...

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Research

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Medicine

1.7K Views.  National Autonomous University of Mexico. Het doel van dit onderzoek is om de klinische toepasbaarheid van de fasehoek aan te tonen door middel van bio-elektrische impedantieanalyse en Z-score-analyse binnen de afdeling spoedeisende hulp en hoe fasehoek een voorspellende marker kan zijn voor overlijden of heropname 90 dagen na ontslag. Recent onderzoek is gericht op het bestuderen van de rol van fasehoekcongestie en verminderde lichaamscelmassa door bio-elektrische impedantievectoranalyse als voorspellers van een slechte prognose bij...

Video: Auteur in de schijnwerpers: onthulling van prognostische indicatoren bij hartfalen - de rol van fasehoek en bio-elektrische impedantieanalyse 

Lumped-Parameter and Finite Element Modeling of Heart Failure with Preserved Ejection Fraction

Scientific efforts in the field of computational modeling of cardiovascular diseases have largely focused on heart failure with reduced ejection fraction (HFrEF), broadly overlooking heart failure with preserved ejection fraction (HFpEF), which has more recently become a dominant form of heart failure worldwide. Motivated by the paucity of HFpEF in silico representations, two distinct computational models are presented in this paper to simulate the hemodynamics of HFpEF resulting from left ventricular pressure overload. First, an object-oriented lumped-parameter model was developed using a numerical solver. This model is based on a zero-dimensional (0D) Windkessel-like network, which depends on the geometrical and mechanical properties of the constitutive elements and offers the advantage of low computational costs. Second, a finite element analysis (FEA) software package was utilized for the implementation of a multidimensional simulation. The FEA model combines three-dimensional (3D) multiphysics models of the electro-mechanical cardiac response, structural deformations, and fluid cavity-based hemodynamics and utilizes a simplified lumped-parameter model to define the flow exchange profiles among different fluid cavities. Through each approach, both the acute and chronic hemodynamic changes in the left ventricle and proximal vasculature resulting from pressure overload were successfully simulated. Specifically, pressure overload was modeled by reducing the orifice area of the aortic valve, while chronic remodeling was simulated by reducing the compliance of the left ventricular wall. Consistent with the scientific and clinical literature of HFpEF, results from both models show (i) an acute elevation of transaortic pressure gradient between the left ventricle and the aorta and a reduction in the stroke volume and (ii) a chronic decrease in the end-diastolic left ventricular volume, indicative of diastolic dysfunction. Finally, the FEA model demonstrates that stress in the HFpEF myocardium is remarkably higher than in the healthy heart tissue throughout the cardiac cycle.

This work introduces two computational models of heart failure with preserved ejection fraction based on a lumped-parameter approach and finite element analysis. These models are used to evaluate the changes in the hemodynamics of the left ventricle and related vasculature induced by pressure overload and diminished ventricular compliance.

Scientific efforts in the field of computational modeling of cardiovascular diseases have largely focused on heart failure with reduced ejection fraction ...

Engineering

Real-time Pressure-volume Analysis of Acute Myocardial Infarction in Mice

Acute myocardial infarction can lead to acute heart failure and cardiogenic shock. The evaluation of hemodynamics is critical for the evaluation of any potential therapeutic approach directed against acute left ventricular (LV) dysfunction. Current imaging modalities (e.g., echocardiography and magnetic resonance imaging) have several limitations since data on LV pressure cannot directly be measured. LV catheterization in mice undergoing coronary artery occlusion could serve as a novel method for a real-time evaluation of LV function.
At the beginning of the procedure, mice were anesthetized followed by endotracheal intubation. For LV catheterization, the right carotid artery was exposed via middle-neck incision. The catheter was introduced and placed into the LV cavity. Left thoracotomy was conducted and the left main coronary artery (LCA) was ligated. To induce reperfusion, the suture was released after 45 min. Pressure-volume data was recorded at all times.
Ligation of the LCA caused a decrease in LV systolic function as evidenced by a 30% reduction in stroke volume, LV ejection fraction (EF), and cardiac output. Maximum dP/dt as a parameter for LV contractility was also significantly reduced and diastolic function was severely impaired (minimum dP/dt -40%). Reperfusion over a period of 20 min did not lead to a complete recovery of LV function.
Real-time pressure-volume analysis served as a valid procedure for monitoring cardiac function during acute myocardial infarction in mice. Maintaining stable anesthesia and a standardized surgical approach was crucial to ensure valid results. As the early phase of acute myocardial infarction is critical for morbidity and mortality, the delineated method could be beneficial for preclinical evaluation of new strategies for cardioprotection.

Acute myocardial infarction in mice induces acute but incompletely characterized changes in left ventricular (LV) function. LV catheterization in mice undergoing coronary artery occlusion serves as a novel method for a real-time evaluation of LV function.

Acute myocardial infarction can lead to acute heart failure and cardiogenic shock. The evaluation of hemodynamics is critical for the evaluation of any ...

Utilizing Percutaneous Ventricular Assist Devices in Acute Myocardial Infarction Complicated by Cardiogenic Shock

Cardiogenic shock is defined as persistent hypotension, accompanied by evidence of end organ hypo-perfusion. Percutaneous ventricular assist devices (PVADs) are used for the treatment of cardiogenic shock in an effort to improve hemodynamics. Impella is currently the most common PVAD and actively pumps blood from the left ventricle into the aorta. PVADs unload the left ventricle, increase cardiac output and improve coronary perfusion. PVADs are typically placed in the cardiac catheterization laboratory under fluoroscopic guidance via the femoral artery when feasible. In cases of severe peripheral arterial disease, PVADs can be implanted through an alternative access. In this article, we summarize the mechanism of action of PVAD and the data supporting their use in the treatment of cardiogenic shock.

Percutaneous ventricular assist devices are increasingly being utilized in patients with acute myocardial infarction and cardiogenic shock. Herein, we discuss the mechanism of action and hemodynamic effects of such devices. We also review algorithms and best practices for the implantation, management and weaning of these complex devices.

Cardiogenic shock is defined as persistent hypotension, accompanied by evidence of end organ hypo-perfusion. Percutaneous ventricular assist devices ...

Use of a Percutaneous Ventricular Assist Device/Left Atrium to Femoral Artery Bypass System for Cardiogenic Shock

The left atrial to femoral artery bypass (LAFAB) system is a mechanical circulatory support (MCS) device used in cardiogenic shock (CS) that bypasses the left ventricle by draining blood from the left atrium (LA) and returning it to the systemic arterial circulation via the femoral artery. It can provide flows ranging from 2.5-5 L/min depending on the size of the cannula. Here, we discuss the mechanism of action of LAFAB, available clinical data, indications for its use in cardiogenic shock, steps of implantation, post-procedural care, and complications associated with the use of this device and their management.
We also provide a brief video of the procedural component of device therapy, including the pre-placement preparation, percutaneous placement of the device via transseptal puncture under echocardiographic guidance and the post-operative management of device parameters.

The following article describes the stepwise procedure for placement of a device (e.g., Tandemheart) in cardiogenic shock (CS) that is a percutaneous left ventricular assist device (pLVAD) and a left atrial to femoral artery bypass (LAFAB) system that bypasses and supports the left ventricle (LV) in CS.

The left atrial to femoral artery bypass (LAFAB) system is a mechanical circulatory support (MCS) device used in cardiogenic shock (CS) that bypasses the ...

Transthoracic Echocardiography to Assess Post-Resuscitation Left Ventricular Dysfunction After Acute Myocardial Infarction and Cardiac Arrest in Pigs

One of the main causes of out-of-hospital cardiac arrest is acute myocardial infarction (AMI). After successful resuscitation from cardiac arrest, approximately 70% of patients die before hospital discharge due to post-resuscitation myocardial and cerebral dysfunction. In experimental models, myocardial dysfunction after cardiac arrest, characterized by an impairment in both left ventricular (LV) systolic and diastolic function, has been described as reversible but very little data are available in cardiac arrest models associated with AMI in pigs. Transthoracic echocardiography is the first-line diagnostic test for the assessment of myocardial dysfunction, structural changes and/or AMI extension. In this pig model of ischemic cardiac arrest, echocardiography was done at baseline and 2-4 and 96 hours after resuscitation. In the acute phase, the examinations are done in anesthetized, mechanically ventilated pigs (weight 39.8 &#177; 0.6 kg) and ECG is recorded continuously. Mono- and bi-dimensional, Doppler and tissue Doppler recordings are acquired. Aortic and left atrium diameter, end-systolic and end-diastolic left ventricular wall thicknesses, end-diastolic and end-systolic diameters and shortening fraction (SF) are measured. Apical 2-, 3-, 4-, and 5-chamber views are acquired, LV volumes and ejection fraction are calculated. Segmental wall motion analysis is done to detect the localization and estimate the extent of myocardial infarction. Pulsed Wave Doppler echocardiography is used to record trans-mitral flow velocities from a 4-apical chamber view and trans-aortic flow from a 5-chamber view to calculate LV cardiac output (CO) and stroke volume (SV). Tissue Doppler Imaging (TDI) of LV lateral and septal mitral anulus is recorded (TDI septal and lateral s&#39;, e&#39;, a&#39; velocities). All the recordings and measurements are done according to the recommendations of the American and European Societies of Echocardiography Guidelines.

Transthoracic echocardiography is the first-line diagnostic test for post-resuscitation left ventricular dysfunction and structural changes in a pig model of cardiac arrest.

One of the main causes of out-of-hospital cardiac arrest is acute myocardial infarction (AMI). After successful resuscitation from cardiac arrest, ...

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 ...

Benefits of Cardiac Resynchronization Therapy in an Asynchronous Heart Failure Model Induced by Left Bundle Branch Ablation and Rapid Pacing

It is now well recognized that heart failure (HF) patients with left bundle branch block (LBBB) derive substantial clinical benefits from cardiac resynchronization therapy (CRT), and LBBB has become one of the important predictors for CRT response. The conventional tachypacing-induced HF model has several major limitations, including absence of stable LBBB and rapid reversal of left ventricular (LV) dysfunction after cessation of pacing. Hence, it is essential to establish an optimal model of chronic HF with isolated LBBB for studying CRT benefits. In the present study, a canine model of asynchronous HF induced by left bundle branch (LBB) ablation and 4 weeks of rapid right ventricular (RV) pacing is established. The RV and right atrial (RA) pacing electrodes via the jugular vein approach, together with an epicardial LV pacing electrode, were implanted for CRT performance. Presented here are the detailed protocols of radiofrequency (RF) catheter ablation, pacing leads implantation, and rapid pacing strategy. Intracardiac and surface electrograms during operation were also provided for a better understanding of LBB ablation. Two-dimensional speckle tracking imaging and aortic velocity time integral (aVTI) were acquired to validate the chronic stable HF model with LV asynchrony and CRT benefits. By coordinating ventricular activation and contraction, CRT uniformed the LV mechanical work and restored LV pump function, which was followed by reversal of LV dilation. Moreover, the histopathological study revealed a significant restoration of cardiomyocyte diameter and collagen volume fraction (CVF) after CRT performance, indicating a histologic and cellular reverse remodeling elicited by CRT. In this report, we described a feasible and valid method to develop a chronic asynchronous HF model, which was suitable for studying structural and biologic reverse remodeling following CRT.

The establishment of a chronic asynchronous heart failure (HF) model by rapid pacing combined with left bundle branch ablation is presented. Two-dimensional speckle tracking imaging and aortic velocity time integral are applied to validate this stable HF model with left ventricular asynchrony and the benefits of cardiac resynchronization therapy.

It is now well recognized that heart failure (HF) patients with left bundle branch block (LBBB) derive substantial clinical benefits from cardiac ...

Biology

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.

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 ...

Ascending Aortic Banding for Studying Pressure-Overload Induced Heart Failure

A Minimally Invasive Model of Aortic Stenosis in Swine

Large animal models of heart failure play an essential role in the development of new therapeutic interventions due to their size and physiological similarities to humans. Efforts have been dedicated to creating a model of pressure-overload induced heart failure, and ascending aortic banding while still supra-coronary and not a perfect mimic of aortic stenosis in humans, closely resembling the human condition.
The purpose of this study is to demonstrate a minimally invasive approach to induce left ventricular pressure overload by placing an aortic band, precisely calibrated with percutaneously introduced high-fidelity pressure sensors. This method represents a refinement of the surgical procedure (3Rs), resulting in homogenous trans-stenotic gradients and reduced intragroup variability. Additionally, it enables swift and uneventful animal recovery, leading to minimal mortality rates. Throughout the study, animals were followed for up to 2 months after surgery, employing transthoracic echocardiography and pressure-volume loop analysis. However, longer follow-up periods can be achieved if desired. This large animal model proves valuable for testing new drugs, particularly those targeting hypertrophy and the structural and functional alterations associated with left ventricular pressure overload.

Author Spotlight: Development of a Minimally Invasive Large-Animal Model for Reliable and Reproducible Cardiovascular Research 

This protocol describes a minimally invasive surgical procedure for ascending aortic banding in swine.

Large animal models of heart failure play an essential role in the development of new therapeutic interventions due to their size and physiological ...

POCUS Protocol for IVC Assessment in Management of Heart Failure

Workflow and Framework for Collecting and Implementing Point-of-Care Ultrasound Data in the Management of Heart Failure Patients

Management and prevention of acute decompensated heart failure remain highly prevalent and challenging medical conditions. Incorporation of Point-of-Care Ultrasound (POCUS) as an adjunctive tool for assessing volume status and treatment response has shown significant promise. POCUS can be used for imaging internal anatomic structures serially and capturing these images for comparison and measurement over time. This protocol describes a scalable and standardized methodology for the serial assessment of the inferior vena cava (IVC). The methodology includes serial image collection, measurement, and presentation in the electronic medical record. A workflow for POCUS-acquired images of the IVC was created to capture the images and measure the diameter in a discrete data field for direct comparison over time and in response to clinical management. The protocol also includes the assessment of the presence or absence of pleural effusion as discrete data in the standardized workflow. By integrating POCUS into heart failure management, clinicians can improve patient outcomes through more precise and timely adjustments in treatment.

Author Spotlight: Workflow for Integrating POCUS Data into EHR for Managing Heart Failure Patients

This protocol presents a scalable workflow for the use of point-of-care ultrasound in the management of hospitalized and outpatient heart failure patients.

Management and prevention of acute decompensated heart failure remain highly prevalent and challenging medical conditions. Incorporation of Point-of-Care ...

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

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