This research was supported by the Intramural Research Program of the NIH, National Institute on Aging and the Baltimore Longitudinal Study on Aging. A portion of that support was through an R&amp;D contract with MedStar Research Institute. Standard protocol and technical expertise was provided by AtCor.

1. Procedure
<ol>
	<li>Open the software via the shortcut on your Windows desktop by double-clicking on the icon.</li>
	<li>Click Patient to activate the Patient Screen.</li>
	<li>To enter a new patient into the database, click the New button in the patient search area, and then click on the Yes button to confirm you would like to enter a new patient.</li>
	<li>Enter patient details such as last name, first name, date of birth, and gender. Click on the Save button to advance to the next step.</li>
	<li>Click the PWA or PWV button to perform measurement. If only one of these modes is available, there is no need to click on the button, simply proceed to the study screen.</li>
</ol>
2. Central Blood Pressure Measurement Using Pulse Wave Analysis (PWA)
<ol>
	<li>Click on the Study button to enter study parameters. Enter the brachial pressure taken from a calibrated sphygmomanometer and any other details you wish to include.</li>
	<li>Click on the Capture Data button to proceed with a measurement. Attach the three ECG electrodes and leads to the patient in a modified Lead II configuration or using the patient&#39;s limbs as indicated on the cables.</li>
	<li>Palpate the patient&#39;s radial artery. This is located on the lateral of the wrist, immediately above the wrist joint near the base of the thumb. Gently press the radial artery against the underlying bone with the middle and index fingers.</li>
	<li>Place the tonometer over the strongest pulse point. Gently press the tonometer down until you see a consistent pressure waveform displayed on the data capture screen.</li>
	<li>If Auto Capture is enabled (see Note below), the system will automatically save the measurement. To manually save the measurement for analysis, press the spacebar on your keyboard (or step on the footswitch, if used).</li>
	<li>If a repeat measurement is required with the same study parameters, click on the Repeat button to return to the Capture Data screen and repeat the measurement as outlined in steps 2.4-2.5 above.</li>
	<li>To perform a measurement on a new patient, click on the Patient button and return to step 1.3 above.</li>
</ol>
3. Arterial Stiffness Measurement Using Pulse Wave Velocity (PWV)
<ol>
	<li>Click on the Study button to enter study parameters.</li>
	<li>Enter brachial pressure taken from a calibrated sphygmomanometer 
	Enter the distance measured for the distal (supra-sternal notch to femoral pulse) and proximal (supra-sternal notch to carotid pulse) sites. Medication, Notes, and Operator fields may be entered, if desired</li>
	<li>Click on the Capture button to proceed with the measurement.</li>
	<li>Ensure the ECG signal is of acceptable quality.</li>
	<li>Palpate the carotid artery pulse. This is located between the larynx and the sternocleidomastoid muscle in the neck. It can be felt by pushing the muscle to the side and pressing the artery against the larynx.</li>
	<li>Place the tonometer on the carotid artery and gently press the tonometer down until you receive a consistent pressure waveform displayed on the data capture screen.</li>
	<li>When you have a minimum of 13 sec of consistent waveforms, click the OK button or (press on the footswitch, if used).</li>
	<li>Palpate the femoral artery pulse. This is located over the ventral thigh halfway between the pubic symphysis and anterior superior iliac spine.</li>
	<li>Place the tonometer on the femoral artery and gently press the tonometer down until you receive a consistent pressure waveform displayed on the capture screen. When you have a minimum of 13 sec of consistent waveforms, click the OK button (or press the on the footswitch, if used).</li>
	<li>The report(s) can now be reviewed. These measurements are typically conducted in triplicate. If the user wishes to measure the PWV between carotid and radial arteries, these steps just shown would be repeated except that instead of measuring at the femoral artery, the user would place the tonometer at the radial artery. To perform a measurement on a new patient, click on the Study button and repeat this procedure or use the Search feature to search for an existing patient.</li>
</ol>
4. Shut Down
<ol>
	<li>The software automatically saves all reports. To close the software, click on System from the main menu, and then click on Exit. Place the tonometer in the module tray for storage.</li>
</ol>

<ol>
	<li>Najjar, S. S., Scuteri, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pulse+wave+velocity+is+an+independent+predictor+of+the+longitudinal+increase+in+systolic+blood+pressure+and+of+incident+hypertension+in+the+Baltimore+Longitudinal+Study+of+Aging.">Pulse wave velocity is an independent predictor of the longitudinal increase in systolic blood pressure and of incident hypertension in the Baltimore Longitudinal Study of Aging.</a> J. Am. Coll. Cardiol. 51 (14), 1377-1383 (2008).</li><li>Doonan, R. J., Scheffler, P., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Altered+arterial+stiffness+and+subendocardial+viability+ratio+in+young+healthy+light+smokers+after+acute+exercise.">Altered arterial stiffness and subendocardial viability ratio in young healthy light smokers after acute exercise.</a> PloS one. 6 (10), (2011).</li><li>Laurent, S., Cockcroft, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Expert+consensus+document+on+arterial+stiffness:+methodological+issues+and+clinical+applications.">Expert consensus document on arterial stiffness: methodological issues and clinical applications.</a> Eur. Heart J. 27 (21), 2588-2605 (2006).</li><li>Mitchell, G. F., Hwang, S. -. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Arterial+stiffness+and+cardiovascular+events:+the+Framingham+Heart+Study.">Arterial stiffness and cardiovascular events: the Framingham Heart Study.</a> Circulation. 121 (4), 505-511 (2010).</li><li>Abbatecola, A. M., Chiodini, P., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pulse+wave+velocity+is+associated+with+muscle+mass+decline:+Health+ABC+study.">Pulse wave velocity is associated with muscle mass decline: Health ABC study.</a> Age. , (2011).</li><li>Watson, N. L., Sutton-Tyrrell, K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Arterial+stiffness+and+gait+speed+in+older+adults+with+and+without+peripheral+arterial+disease.">Arterial stiffness and gait speed in older adults with and without peripheral arterial disease.</a> Am. J. Hypertens. 24 (1), 90-95 (2011).</li><li>Mackenzie, I. S., Wilkinson, I. B., Cockcroft, J. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Assessment+of+arterial+stiffness+in+clinical+practice.">Assessment of arterial stiffness in clinical practice.</a> QJM. 95 (2), 67-74 (2002).</li><li>O'Rourke, M. F., Pauca, A., Jiang, X. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pulse+wave+analysis.">Pulse wave analysis.</a> Br. J. Clin. Pharmacol. 51 (6), 507-522 (2001).</li><li>Stoner, L., Young, J. M., Fryer, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Assessments+of+arterial+stiffness+and+endothelial+function+using+pulse+wave+analysis.">Assessments of arterial stiffness and endothelial function using pulse wave analysis.</a> Int. J. Vasc. Med. 2012, 903107 (2012).</li><li>Farro, I., Bia, D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pulse+wave+velocity+as+marker+of+preclinical+arterial+disease:+reference+levels+in+a+uruguayan+population+considering+wave+detection+algorithms,+path+lengths,+aging,+and+blood+pressure.">Pulse wave velocity as marker of preclinical arterial disease: reference levels in a uruguayan population considering wave detection algorithms, path lengths, aging, and blood pressure.</a> Int. J. Hypertens. 2012, (2012).</li><li>Lakatta, E. G., Wang, M., Najjar, S. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Arterial+aging+and+subclinical+arterial+disease+are+fundamentally+intertwined+at+macroscopic+and+molecular+levels.">Arterial aging and subclinical arterial disease are fundamentally intertwined at macroscopic and molecular levels.</a> Med. Clin. N. Am. 93 (3), 583-604 (2009).</li><li>Ambrose, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Clinical Manual (CVMS) Rev. 2, 1-51 (2011).</li><li>. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Reference+Values+for+Arterial+Stiffness'+Collaboration+Determinants+of+pulse+wave+velocity+in+healthy+people+and+in+the+presence+of+cardiovascular+risk+factors:+'establishing+normal+and+reference+values.">Reference Values for Arterial Stiffness' Collaboration Determinants of pulse wave velocity in healthy people and in the presence of cardiovascular risk factors: 'establishing normal and reference values.</a> Eur. Heart J. 31 (19), 2338-2350 (2010).</li><li>van Bortel, L. M., Laurent, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Expert+consensus+document+on+the+measurement+of+aortic+stiffness+in+daily+practice+using+carotid-femoral+pulse+wave+velocity.">Expert consensus document on the measurement of aortic stiffness in daily practice using carotid-femoral pulse wave velocity.</a> J. Hypertens. 30 (3), 445-448 (2012).</li><li>Scuteri, A., Brancati, A., Gianni, W., Assisi, A., Volpe, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Arterial+stiffness+is+an+independent+risk+factor+for+cognitive+impairment+in+the+elderly:+a+pilot+study.">Arterial stiffness is an independent risk factor for cognitive impairment in the elderly: a pilot study.</a> J. Hypertens. 23 (6), 1211 (2005).</li><li>Khoshdel, A. R., Carney, S. L., Nair, B. R., Gillies, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Better+management+of+cardiovascular+diseases+by+pulse+wave+velocity:+combining+clinical+practice+with+clinical+research+using+evidence-based+medicine.">Better management of cardiovascular diseases by pulse wave velocity: combining clinical practice with clinical research using evidence-based medicine.</a> Clin. Med. Res. 5 (1), 45-52 (2007).</li></ol>

The authors declare that they have no competing financial interests. The authors received assistance with protocol description and performance of study from SphygmoCor which manufactures this product described.

The measurement of pulse wave velocity (PWV) is a noninvasive method for analyzing central arterial stiffness in a relatively simple and reproducible manner3. To assess PWV, the carotid (as a surrogate for the descending aorta) and femoral pulse waveforms are acquired using a high-fidelity tonometer; the time delay in pulse wave arrival at the between the two sites is estimated referencing to a concurrently recorded EKG waves by custom designed computer software that conforms to the propagative model of the ar...

A correction was made to <a href="http://www.jove.com/video/50817">Pulse Wave Velocity Testing in the Baltimore Longitudinal Study of Aging</a>. There was an error with the author, Majd AlGhatrif's, name. The author's name has been corrected to:
Majd AlGhatrif
instead of:
Majd al Ghatrif

A correction to the author list has been made for article <a href="http://www.jove.com/video/50817">Pulse Wave Velocity Testing in the Baltimore Longitudinal Study of Aging</a>.

Erratum: Pulse Wave Velocity Testing in the Baltimore Longitudinal Study of Aging

Pulse Wave Velocity (PWV) is regarded as the gold standard in the assessment of arterial stiffness2. While not used clinically in the United States, it has been validated and widely used in clinical settings throughout Europe3. Changes in PWV have been correlated with cardiovascular risk factors such as hypertension, obesity, impaired glucose tolerance, and dyslipidemia. Higher aortic stiffness has been associated with increased risk for a first cardiovascular event4, muscle mass decline5, and slower gait speed in subjects with peripheral arterial disease6. Assessment of PWV is accomplished by analyzing the speed with which a pulse of blood travels from the carotid artery to the femoral artery7. It is a relatively simple method with highly reproducible results. Advances in technology continue to simplify the procedure, reducing operator dependency and decreasing the amount of time required for the exam. The system used in our laboratory is produced by SphygmoCorand utilizes an EKG and a high-fidelity tonometer to acquire waveforms from the carotid and femoral pulses. The software then analyzes these variables to determine the velocity by 1) estimating the time that the pulse wave takes to travel between the carotid and femoral sites by referencing the timing of the pressure wave arrival at each arterial site relative to the electrocardiographic waveforms 2) dividing the measured distance between the two sites by the estimated time. The closer together the sampling sites, the less accurate the PWV, limiting the use of this method to larger vessels such as the femoral and carotid arteries. In addition to determining PWV, the system can calculate the pressure in the ascending aorta by applying a transfer function to the waveform produced by the radial pulse8 which is the &#34;central pressure&#34; and the pressure that most directly impacts the heart at time of ejection. This information can aid in the assessment of the arterial system&#39;s effect on the left ventricle in a reliable and noninvasive manner9. Alternative techniques used for the examination of vascular stiffness, such as carotid distensibility via echo tracking, require a great deal of technical expertise and are more time consuming than the PWV. Echo tracking also generally utilizes video-image analysis and therefore the accuracy of these measurements are limited3. Other techniques for examining vascular changes include assessment of carotid-intima medial thickness (IMT) which provides results more closely related to atherosclerotic progression although the cross-sectional and transverse images obtained can provide a crude approximation of carotid elastance. This method, however, is plagued by some of the same constraints as the distensibility studies described above. As researchers continue to look at the role arterial stiffness plays in various disease states, PWV measurement will likely continue to provide a quantitative and reproducible surrogate endpoint.

<table><tbody><tr><td>SphygmoCor System</td><td>AtCor</td><td>SPT-304, Module EM3</td><td></td></tr></tbody></table>

pulse wave velocity testing in the baltimore longitudinal study of aging

Carotid-femoral pulse wave velocity is considered the gold standard for measurements of central arterial stiffness obtained through noninvasive methods1.&#160;Subjects are placed in the supine position and allowed to rest quietly for at least 10 min prior to the start of the exam. The proper cuff size is selected and a blood pressure is obtained using an oscillometric device. Once a resting blood pressure has been obtained, pressure waveforms are acquired from the right femoral and right common carotid arteries. The system then automatically calculates the pulse transit time between these two sites (using the carotid artery as a surrogate for the descending aorta). Body surface measurements are used to determine the distance traveled by the pulse wave between the two sampling sites. This distance is then divided by the pulse transit time resulting in the pulse wave velocity. The measurements are performed in triplicate and the average is used for analysis.

<img alt="Table 1" fo:content-width="5in" fo:src="/files/ftp_upload/50817/50817table1highres.jpg" src="/files/ftp_upload/50817/50817table1.jpg" /> 
Table 1.&#160;PWV results are produced in meters per second. In healthy subjects, these speeds can range from an average 6.2 m/sec (in subjects under 30) to 10.9 m/sec (in subjects 70 and older). These values were established in the article &#34;Determinants of pulse wave velocity in healthy People and in the presenc...

Watch this Scientific Journal Video about Pulse Wave Velocity Testing in the Baltimore Longitudinal Study of Aging at JoVE.com

Pulse Wave Velocity Testing in the Baltimore Longitudinal Study of Aging

Pulse wave velocity (PWV) measurement assesses arterial stiffness by a tonometry-based system that measures the speed with which arterial pressure wave travels along the arterial tree, typically approximating the time that it takes this wave to travel from the descending aorta (using the carotid artery as a surrogate) to the femoral artery. Carotid-femoral PWV increases two- to threefold across the adult lifespan.

Carotid-femoral pulse wave velocity is considered the gold standard for measurements of central arterial stiffness obtained through noninvasive ...

pulse-wave-velocity-testing-baltimore-longitudinal-study

Research

Education

JoVE Core

JoVE Journal

Nursing

Medicine

Unit 1

Vital Signs: Pulse

SCIENTISTS IN ACTION

17.0K Views.  National Institute of Aging. Pulse wave velocity (PWV) measurement assesses arterial stiffness by a tonometry-based system that measures the speed with which arterial pressure wave travels along the arterial tree, typically approximating the time that it takes this wave to travel from the descending aorta (using the carotid artery as a surrogate) to the femoral artery. Carotid-femoral PWV increases two- to threefold across the adult lifespan.

Video: Pulse Wave Velocity Testing in the Baltimore Longitudinal Study of Aging

Biomarkers in an Animal Model for Revealing Neural, Hematologic, and Behavioral Correlates of PTSD

Identification of biomarkers representing the evolution of the pathophysiology of Post Traumatic Stress Disorder (PTSD) is vitally important, not only for objective diagnosis but also for the evaluation of therapeutic efficacy and resilience to trauma. Ongoing research is directed at identifying molecular biomarkers for PTSD, including traumatic stress induced proteins, transcriptomes, genomic variances and genetic modulators, using biologic samples from subjects' blood, saliva, urine, and postmortem brain tissues. However, the correlation of these biomarker molecules in peripheral or postmortem samples to altered brain functions associated with psychiatric symptoms in PTSD remains unresolved. Here, we present an animal model of PTSD in which both peripheral blood and central brain biomarkers, as well as behavioral phenotype, can be collected and measured, thus providing the needed correlation of the central biomarkers of PTSD, which are mechanistic and pathognomonic but cannot be collected from people, with the peripheral biomarkers and behavioral phenotypes, which can.
Our animal model of PTSD employs restraint and tail shocks repeated for three continuous days - the inescapable tail-shock model (ITS) in rats. This ITS model mimics the pathophysiology of PTSD 17, 7, 4, 10. We and others have verified that the ITS model induces behavioral and neurobiological alterations similar to those found in PTSD subjects 17, 7, 10, 9. Specifically, these stressed rats exhibit (1) a delayed and exaggerated startle response appearing several days after stressor cessation, which given the compressed time scale of the rat's life compared to a humans, corresponds to the one to three months delay of symptoms in PTSD patients (DSM-IV-TR PTSD Criterian D/E 13), (2) enhanced plasma corticosterone (CORT) for several days, indicating compromise of the hypothalamopituitary axis (HPA), and (3) retarded body weight gain after stressor cessation, indicating dysfunction of metabolic regulation.
The experimental paradigms employed for this model are: (1) a learned helplessness paradigm in the rat assayed by measurement of acoustic startle response (ASR) and a charting of body mass; (2) microdissection of the rat brain into regions and nuclei; (3) enzyme-linked immunosorbent assay (ELISA) for blood levels of CORT; (4) a gene expression microarray plus related bioinformatics tools 18. This microarray, dubbed rMNChip, focuses on mitochondrial and mitochondria-related nuclear genes in the rat so as to specifically address the neuronal bioenergetics hypothesized to be involved in PTSD.

We describe a rat model of post traumatic stress disorder (PTSD) that reveals the persistent alterations in neuroendocrine function and the delayed long-term, exaggerated fear response, characteristic of PTSD patients. The animal model and methods described here are useful for correlating biomarkers in brain nuclei, which are mechanistic but cannot be measured in patients, with biomarkers in peripheral white blood cells, which can.

Identification of biomarkers representing the evolution of the pathophysiology of Post Traumatic Stress Disorder (PTSD) is vitally important, not only for ...

Tilt Testing with Combined Lower Body Negative Pressure: a "Gold Standard" for Measuring Orthostatic Tolerance

Orthostatic tolerance (OT) refers to the ability to maintain cardiovascular stability when upright, against the hydrostatic effects of gravity, and hence to maintain cerebral perfusion and prevent syncope (fainting). Various techniques are available to assess OT and the effects of gravitational stress upon the circulation, typically by reproducing a presyncopal event (near-fainting episode) in a controlled laboratory environment. The time and/or degree of stress required to provoke this response provides the measure of OT. Any technique used to determine OT should: enable distinction between patients with orthostatic intolerance (of various causes) and asymptomatic control subjects; be highly reproducible, enabling evaluation of therapeutic interventions; avoid invasive procedures, which are known to impair OT1.
In the late 1980s head-upright tilt testing was first utilized for diagnosing syncope2. Since then it has been used to assess OT in patients with syncope of unknown cause, as well as in healthy subjects to study postural cardiovascular reflexes2-6. Tilting protocols comprise three categories: passive tilt; passive tilt accompanied by pharmacological provocation; and passive tilt with combined lower body negative pressure (LBNP). However, the effects of tilt testing (and other orthostatic stress testing modalities) are often poorly reproducible, with low sensitivity and specificity to diagnose orthostatic intolerance7.
Typically, a passive tilt includes 20-60 min of orthostatic stress continued until the onset of presyncope in patients2-6. However, the main drawback of this procedure is its inability to invoke presyncope in all individuals undergoing the test, and corresponding low sensitivity8,9. Thus, different methods were explored to increase the orthostatic stress and improve sensitivity.
Pharmacological provocation has been used to increase the orthostatic challenge, for example using isoprenaline4,7,10,11 or sublingual nitrate12,13. However, the main drawback of these approaches are increases in sensitivity at the cost of unacceptable decreases in specificity10,14, with a high positive response rate immediately after administration15. Furthermore, invasive procedures associated with some pharmacological provocations greatly increase the false positive rate1.
Another approach is to combine passive tilt testing with LBNP, providing a stronger orthostatic stress without invasive procedures or drug side-effects, using the technique pioneered by Professor Roger Hainsworth in the 1990s16-18. This approach provokes presyncope in almost all subjects (allowing for symptom recognition in patients with syncope), while discriminating between patients with syncope and healthy controls, with a specificity of 92%, sensitivity of 85%, and repeatability of 1.1&plusmn;0.6 min16,17. This allows not only diagnosis and pathophysiological assessment19-22, but also the evaluation of treatments for orthostatic intolerance due to its high repeatability23-30. For these reasons, we argue this should be the "gold standard" for orthostatic stress testing, and accordingly this will be the method described in this paper.

We describe a "gold standard" for evaluating orthostatic tolerance (OT) using tilt testing with combined lower body negative pressure (LBNP). This can be combined with non-invasive evaluations of cardiovascular reflex control. Normal and abnormal responses are defined.

Orthostatic tolerance (OT)  refers to the ability to maintain cardiovascular stability when upright,  against the hydrostatic effects of gravity, and ...

Orthotopic Aortic Transplantation in Mice for the Study of Vascular Disease

Vascular procedures involving anastomoses in the mouse are generally thought to be difficult and highly dependent on the skill of the individual surgeon. This is largely true, but there are a number of important principles that can reduce the difficulty of these procedures and enhance reproducibility. Orthotopic aortic transplantation is an excellent procedure in which to learn these principles because it involves only two end-to-end anastomoses, but requires good suturing technique and handling of the vessels for consistent success. This procedure begins with the procurement of a length of abdominal aorta from a donor animal, followed by division of the native aorta in the recipient. The procured aorta is then placed between the divided ends of the recipient aorta and sutured into place using end-to-end anastomoses. To accomplish this objective successfully requires a high degree of concentration, good tools, a steady hand, and an appreciation of how easily the vasculature of a mouse can be damaged, resulting in thrombosis. Learning these important principles is what occupies most of the beginner's time when learning microsurgery in small rodents. Throughout this protocol, we refer to these important points. This model can be used to study vascular disease in a variety of different experimental systems1-8. In the context shown here, it is most often used for the study of post-transplant vascular disease, a common long-term complication of solid organ transplantation in which intimal hyperplasia occurs within the allograft. The primary advantage of the model is that it facilitates quantitative morphometric analyses and the transplanted vessel lies contiguous to the endogenous vessel, which can serve as an additional control9. The technique shown here is most often used for mice weighing 18-25 grams. We have accumulated most of our experience using the C57BL/6J, BALB/cJ, and C3H/HeJ strains.

We describe a technique in which a section of the abdominal aorta from a mouse is transplanted orthotopically to just below the renal arteries in an allogeneic or syngeneic recipient. This technique can be useful in studies in which transplantation of large arteries of uniform size is deemed advantageous.

Vascular procedures involving anastomoses in the mouse are generally thought to be difficult and highly dependent on the skill of the individual surgeon. ...

Ultrasound-based Pulse Wave Velocity Evaluation in Mice

Arterial stiffness can be evaluated by calculating pulse wave velocity (PWV), i.e., the speed with which the pulse wave travels in a conduit vessel. This parameter is being increasingly investigated in small rodent models in which it is used for assessing alterations in vascular function related to particular genotypes/treatments or for characterizing cardiovascular disease progression. This protocol describes an image processing algorithm which leads to non-invasive arterial PWV measurement in mice using ultrasound (US) images only. The proposed technique has been used to assess abdominal aorta PWV in mice and evaluate its age-associated changes.
Abdominal aorta US scans are obtained from mice under gaseous anesthesia using a specific US device equipped with high-frequency US probes. B-mode and Pulse-Wave Doppler (PW-Doppler) images are analyzed in order to obtain diameter and mean velocity instantaneous values, respectively. For this purpose, edge detection and contour tracking techniques are employed. The single-beat mean diameter and velocity waveforms are time aligned and combined in order to achieve the diameter-velocity (lnD-V) loop. PWV values are obtained from the slope of the linear part of the loop, which corresponds to the early systolic phase.
With the present approach, anatomical and functional information about the mouse abdominal aorta can be non-invasively achieved. Requiring the processing of US images only, it may represent a useful tool for the non-invasive characterization of different arterial sites in the mouse in terms of elastic properties. The application of the present technique can be easily extended to other vascular districts, such as the carotid artery, thus providing the possibility to obtain a multi-site arterial stiffness assessment.

Arterial stiffness represents a key factor in cardiovascular disease and pulse wave velocity (PWV) can be considered as a surrogate index for arterial stiffness. This protocol describes an image processing algorithm for calculating PWV in mice based on ultrasound image processing that is applicable at different arterial sites.

Arterial stiffness can be evaluated by calculating pulse wave velocity (PWV), i.e., the speed with which the pulse wave travels in a conduit vessel. This ...

Measuring the Carotid to Femoral Pulse Wave Velocity (Cf-PWV) to Evaluate Arterial Stiffness

For the elderly, arterial stiffening is a good marker for aging evaluation and it is recommended that the arterial stiffness be determined noninvasively by the measurement of carotid to femoral pulse wave velocity (cf-PWV) (Class I; Level of Evidence A). In literature, numerous community-based or disease-specific studies have reported that higher cf-PWV is associated with increased cardiovascular risk. Here, we discuss strategies to evaluate arterial stiffness with cf-PWV. Following the well-defined steps detailed here, e.g., proper position operator, distance measurement, and tonometer position, we will obtain a standard cf-PWV value to evaluate arterial stiffness. In this paper, a detailed stepwise method to record a good quality PWV and pulse wave analysis (PWA) using a non-invasive tonometry-based device will be discussed.

Measuring the Carotid to Femoral Pulse Wave Velocity Cf-PWV to Evaluate Arterial Stiffness

This protocol describes a method to standardize the measurements of carotid-femoral pulse wave velocity to evaluate arterial stiffness.

For the elderly, arterial stiffening is a good marker for aging evaluation and it is recommended that the arterial stiffness be determined noninvasively ...

Measurement of Pulse Propagation Velocity, Distensibility and Strain in an Abdominal Aortic Aneurysm Mouse Model

An abdominal aortic aneurysm (AAA) is defined as a localized dilation of the abdominal aorta that exceeds the maximal intraluminal diameter (MILD) by 1.5 times of its original size. Clinical and experimental studies have shown that small aneurysms may rupture, while a subpopulation of large aneurysms may remain stable. Thus, in addition to the measurement of intraluminal diameter of the aorta, knowledge of structural traits of the vessel wall may provide important information to assess the stability of the AAA. Aortic stiffening has recently emerged as a reliable tool to determine early changes in the vascular wall. Pulse propagation velocity (PPV) along with the distensibility and radial strain are highly useful ultrasound-based methods relevant for assessing aortic stiffness. The primary purpose of this protocol is to provide a comprehensive technique for the use of ultrasound imaging system to acquire images and analyze the structural and functional properties of the aorta as determined by MILD, PPV, distensibility and radial strain.

This manuscript describes a detailed protocol for using high frequency ultrasound imaging to measure luminal diameter, pulse propagation velocity, distensibility and radial strain on a mouse model of abdominal aortic aneurysm.

An abdominal aortic aneurysm (AAA) is defined as a localized dilation of the abdominal aorta that exceeds the maximal intraluminal diameter (MILD) by 1.5 ...

Immunology and Infection

Cortical Bone Assessment Using the Ultrasonic BDAT Device

Cortical Bone Assessment Using Ultrasonic Guided Waves: A Reproducibility Study in a Healthy Population

Fragility fractures are still a worldwide health burden in the context of population aging. In particular, the global number of hip fractures is expected to double between 2020 and 2050. Therefore, it is essential to detect patients at risk of fragility fracture at the population scale. The current golden standard is dual X-ray absorptiometry (DXA), providing the areal bone mineral density (aBMD). Ultrasonic devices, usually more portable and cheaper than X-ray devices, represent interesting DXA alternatives as screening tools. However, operator dependency is usually recognized as their main drawback. In this study, the measurement protocol of the bi-directional axial transmission (BDAT) ultrasonic device is presented in detail. The dedicated ultrasonic probe is placed at the one-third distal radius of the non-dominant forearm using conventional coupling gel. The guided interface provides in quasi-real time (about 2 Hz) four parameters of interest: velocities of the first arriving signal (vFAS) and the A0 mode (vA0),&#160;cortical thickness (Ct.Th) and porosity (Ct.Po), as well as four quality parameters. The operator moves the probe slowly at the measurement site, carefully observing the feedback provided by the interface until finding a stable position and starting a series of 10 acquisitions. When at least four consistent series are obtained, the measurement ends, and an automatic report is generated. The measurement usually takes about 5 min to complete. To determine the robustness of this protocol, a reproducibility study was conducted among 3 operators (one expert and two novices) and 14 healthy participants (6 women, 8 men, 21-53 years old). The intraclass correlation coefficients (ICC) were found good for vA0 (0.76), Ct.Po (0.80) or excellent for Ct.Th (0.87) and vFAS (0.91). The standard deviations were found to be less than 10% of the total ranges in clinical practice.

Here, we present the measurement protocol of the bi-directional axial transmission (BDAT) ultrasonic device in detail and test it in a reproducibility study, considering 14 healthy participants and 3 operators. Reliability, measured with the intraclass correlation coefficients (ICC), was good to excellent for four parameters of interest.

Fragility fractures are still a worldwide health burden in the context of population aging. In particular, the global number of hip fractures is expected ...

Bioengineering

Assessing Leg Blood Flow in Training Workloads

Doppler Ultrasound-Based Leg Blood Flow Assessment During Single-Leg Knee-Extensor Exercise in an Uncontrolled Setting

Doppler ultrasound has revolutionized the assessment of organ blood flow and is widely used in research and clinical settings. While Doppler ultrasound-based assessment of contracting leg muscle blood flow is common in human studies, the reliability of this method requires further investigation. Therefore, this study aimed to investigate the within-day test-retest, between-day test-retest, and inter-rater reliability of Doppler ultrasound for assessing leg blood flow during rest and graded single-leg knee-extensions (0 W, 6 W, 12 W, and 18 W), with the ultrasound probe being removed between measurements. The study included thirty healthy subjects (age: 33 &#177; 9.3, male/female: 14/16) who visited the laboratory on two different experimental days separated by 10 days. The study did not control for major confounders such as nutritional state, time of day, or hormonal status. Across different exercise intensities, the results demonstrated high within-day reliability with a coefficient of variation (CV) ranging from 4.0% to 4.3%, acceptable between-day reliability with a CV ranging from 10.1% to 20.2%, and inter-rater reliability with a CV ranging from 17.9% to 26.8%. Therefore, in a real-life clinical scenario where controlling various environmental factors is challenging, Doppler ultrasound can be used to determine leg blood flow during submaximal single-leg knee-extensor exercise with high within-day reliability and acceptable between-day reliability when performed by the same sonographer.

Author Spotlight: Assessing the Reliability of Doppler Ultrasound in Measuring Leg Blood Flow 

This test-retest study evaluated leg blood flow measured by the Doppler ultrasound technique during single-leg knee-extensor exercise. The within-day, between-day, and inter-rater reliability of the method was investigated. The approach demonstrated high within-day and acceptable between-day reliability. However, the inter-rater reliability was unacceptably low during rest and at low workloads.

Doppler ultrasound has revolutionized the assessment of organ blood flow and is widely used in research and clinical settings. While Doppler ...

Using Arterial Stiffness and Endothelial Function for Cardiovascular Assessment

Pulse-Wave Velocity, Flow-Mediated Dilation, and Carotid Intima-Media Thickness to Assess Cardiovascular Risk in Population with Metabolic Syndrome

Pulse-wave velocity (PWV), flow-mediated dilation (FMD), and carotid intima-media thickness (CIMT) are established methods used in research and clinical settings to assess arterial stiffness, endothelial function, and subclinical atherogenesis. These measurements may reflect vascular disease and atherosclerotic progression, which are major causes of adverse cardiovascular events. These methods are particularly valuable in determining cardiovascular dysfunction among populations with different risk factors, such as diabetes mellitus, hypertension, and other metabolic dysfunction-related conditions. They provide a non-invasive and reliable source of information that complements clinical practice. Early detection, risk assessment, and therapeutic decisions regarding cardiovascular disease can be achieved, ultimately contributing to improved patient outcomes. Traditional tools for evaluating cardiovascular disease do not reveal whether metabolic syndrome affects early subclinical cardiovascular disease in patients with obesity. Recent research has highlighted the importance of including arterial stiffness and endothelial function in a comprehensive cardiovascular assessment. Therefore, the aim of the present study is to describe methods that provide information on early subclinical vascular aging, endothelial dysfunction, and atherogenic disease, enabling vascular-targeted risk stratification among populations with obesity and different metabolic profiles.

Author Spotlight: Assessing the Cardiovascular Profile of Patients with Metabolic Syndrome

Endothelial/vascular aging and atherogenesis are key mechanisms that promote the development of cardiovascular diseases. The present protocol describes methods to evaluate arterial stiffness, endothelial dysfunction, and atherogenesis in patients with related risk factors, which are highly valuable in the cardiovascular research field.

Pulse-wave velocity (PWV), flow-mediated dilation (FMD), and carotid intima-media thickness (CIMT) are established methods used in research and clinical ...

Peripheral Vascular Exam Using a Continuous Wave Doppler

Source: Joseph Donroe, MD, Internal Medicine and Pediatrics, Yale School of Medicine, New Haven, CT
Peripheral vascular disease (PVD) is a common condition affecting older adults and includes disease of the peripheral arteries and veins. While the history and physical exam offer clues to its diagnosis, Doppler ultrasound has become a routine part of the bedside vascular examination. The video titled &#34;The Peripheral Vascular Exam&#34; gave a detailed review of the physical examination of the peripheral arterial and venous systems. This video specifically reviews the bedside assessment of peripheral arterial disease (PAD) and chronic venous insufficiency using a handheld continuous wave Doppler.
The handheld Doppler (HHD) is a simple instrument that utilizes continuous transmission and reception of ultrasound (also referred to as continuous wave Doppler) to detect changes in blood velocity as it courses through a vessel. The Doppler probe contains a transmitting element that emits ultrasound and a receiving element that detects ultrasound waves (Figure 1). The emitted ultrasound is reflected off of moving blood and back to the probe at a frequency directly related to the velocity of blood flow. The reflected signal is detected and transduced to an audible sound with a frequency directly related to that of the received Doppler signal (thus, faster blood flow produces a higher frequency sound).
<img alt="Figure 1" src="/files/ftp_upload/10123/10123fig1.jpg" /> 
Figure 1. Generation of a Doppler signal. The handheld Doppler emits an ultrasound signal, which is then reflected back by moving blood, and finally received by the Doppler probe.
The HHD is easily used in the office or hospital setting to detect pulses, screen for PAD using the ankle brachial pressure index (ABPI), and localize venous insufficiency. This video reviews these procedures; however, it is not intended to be a comprehensive review of non-invasive vascular testing.