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.
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 there may be left-sided heart disease but there is no evidence for L-CHF. 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.
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. 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® Fallback views (Lisciandro Focused 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. For example, dry lung all Vet BLUE® views rules out L-CHF and the echocardiography can wait until the patient is more stable/tolerant of echocardiography (and empiric loop diuretic therapy is not indicated); and a bounce or flat CVC rules out R-CHF and the echocardiography can wait until the patient is more stable/tolerant of echocardiography.
Our table for maximum heights at the AFAST®-TFAST® Diaphragmatico-Hepatic (DH) view that assists in interpreting CVC findings. Check out the related Blog and our textbook 2nd edition for more detail.
