velocity time integral

Velocity Time Integral is a clinical Doppler ultrasound measurement of blood flow, equivalent to the area under the velocity time curve. The product of VTI (cm/stroke) and the cross sectional area of a valve (cm2) yields a stroke volume (cm3/stroke), which can be used to calculate cardiac output. VTI can be performed across the left ventricular outflow tract (LVOT), carotid artery, or other blood vessels.

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LVOT VTI can be incorporated into a POCUS examination to determine the etiology of shock{{Cite journal|last1=Blanco|first1=Pablo|last2=Aguiar|first2=Francisco Miralles|last3=Blaivas|first3=Michael|date=2015|title=Rapid Ultrasound in Shock (RUSH) Velocity-Time Integral|journal=Journal of Ultrasound in Medicine|language=en|volume=34|issue=9|pages=1691–1700|doi=10.7863/ultra.15.14.08059|pmid=26283755|issn=1550-9613|doi-access=}} or to predict fluid responsiveness.{{Cite journal|last1=Miller|first1=Ashley|last2=Mandeville|first2=Justin|date=June 2016|title=Predicting and measuring fluid responsiveness with echocardiography|journal=Echo Research and Practice|volume=3|issue=2|pages=G1–G12|doi=10.1530/ERP-16-0008|issn=2055-0464|pmc=4989101|pmid=27249550}} LVOT VTI can also be used to monitor cardiac output intra-operatively,{{Cite journal|last1=Perrino|first1=Albert C.|last2=Harris|first2=Stephen N.|last3=Luther|first3=Martha A.|date=1998-08-01|title=Intraoperative Determination of Cardiac Output Using Multiplane Transesophageal Echocardiography A Comparison to Thermodilution|url=https://anesthesiology.pubs.asahq.org/article.aspx?articleid=2027702|journal=Anesthesiology: The Journal of the American Society of Anesthesiologists|language=en|volume=89|issue=2|pages=350–357|doi=10.1097/00000542-199808000-00010|pmid=9710392|s2cid=38009432|issn=0003-3022|doi-access=free|url-access=subscription}} or as method to precisely quantify cardiac output in patients with advanced heart failure.