The figure is taken from a recent Vet Clinics of North America review article by Lisciandro GR, ©2020 but is also explained well in our 2nd edition of Point-of-care Ultrasound Techniques for the Small Animal Practitioner, ©2021.
LEFT-sided Heart Disease – Short-axis Mercedes Benz View – The strategy is that if the sonographer feels there is evidence for left-sided congestive heart failure (L-CHF), then do Vet BLUE®. If Vet BLUE® is “Dry Lung ALL Vet BLUE® Views” there may be left-sided heart disease but there is no evidence for L-CHF. Recheck the patient in 2-4 weeks with Global FAST® with TFAST® echocardiography. Conversely, if Vet BLUE® shows “Wet Lung” in a pattern that supports left-sided CHF, then a work-up is urgently needed along with L-CHF therapy.
RIGHT-sided Heart Disease – Long-axis 4-chamber View – The strategy is that if the sonographer feels there is evidence for right-sided congestive heart failure (R-CHF), then characterize the caudal vena cava (CVC) and hepatic veins at the AFAST®-TFAST® Diaphragmatico-Hepatic (DH) view. If the CVC has a “Bounce” or is “flat” (small maximum height), then R-CHF is not present. There may be right-sided heart disease but there is no evidence for right-sided CHF. Recheck the patient in 2-4 weeks with Global FAST® with TFAST® echocardiography. Conversely, if the CVC is “FAT” (increased maximum height) especially with distended hepatic veins (“Tree Trunk Sign”), these findings supports (Chou et al. PLOS ONE 2021) right-sided CHF, and a work-up is urgently needed along with R-CHF therapy.
Also, the Global FAST® Non-echo Fallback Views (Lisciandro, Editor, Point-of-care Ultrasound Techniques for the Small Animal Practitioner, ©2014, 2021; Lisciandro, J Vet Emerg Crit Care 2o11) provide important information when echocardiography including TFAST® echocardiography views are not possible because of patient status, i.e., instability, needs forms of restraint (physical/chemical). For example, “Dry Lung ALL Vet BLUE® Views” rules out L-CHF and the TFAST® echocardiography (or complete echocardiography) can wait until the patient is more stable/tolerant of echocardiography. Moreover, when there is “Dry Lung ALL Vet BLUE® Views”, empiric loop diuretic therapy is not indicated for pulmonary edema because no clinically relevant pulmonary edema exists. If you still question your finding of “Dry Lung ALL Vet BLUE® Views”, then REPEAT the Global FAST®-Vet BLUE® in 4-6 hours, or during the next patient rounds, or the next recheck exam. A “Bounce” or “flat” CVC rules out R-CHF and the FAST® echocardiography (or complete echocardiography) can wait until the patient is more stable/tolerant of echocardiography. If you still question your finding of “Bounce” or “flat” CVC, then REPEAT the Global FAST®-AFAST®-TFAST® DH View in 4-6 hours, or during the next patient rounds, or the next recheck exam.
Our Table for Maximum Heights of the Caudal Vena Cava (CVC) at the AFAST®-TFAST® Diaphragmatico-Hepatic (DH) view help characterize and interpret CVC findings in addition to “Bounce”, “flat”, and “FAT.” New information, cats should never be over 0.5 cm as their CVC maximum height. Thus, the FASTVet- Lisciandro Rule for the CVC Maximum Height Measurement is now the following – “CVC Maximum Height Rule is <0.5 cm cats, <1.0 cm small dogs, <1.5 cm for large dogs”, thus over these measurements would be considered “FAT” or distended or “Fluid Intolerant” and the hepatic veins “Tree Trunk Sign” is always right-sided congestive heart failure/right-sided volume overload until proven otherwise.
We hope you found this FASTVet Blog helpful. Please send any comments to Dr. Greg Lisciandro, DVM, DAVP, DACVECC at FastSavesLives@gmail.com
